EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: Homer J Simpson on October 29, 2018, 07:54:41 pm
-
Will be interesting to see where this goes.
"A technical log obtained by the BBC from the plane's previous flight suggests that the airspeed reading on the captain's instrument was unreliable, and the altitude readings differed on the captain's and first officer's instruments."
"Identified that CAPT [captain's] instrument was unreliable and handover control to FO [first officer]," the log reads. "Continue NNC of Airspeed Unreliable and ALT disagree."
https://www.bbc.com/news/world-asia-46022390 (https://www.bbc.com/news/world-asia-46022390)
-
The level of redundancy and fault handling automation in a brand new 737 is pretty amazing -, especially on airspeed and altitude.
Patiently waiting to see what happened. I could have been similar to the Air France crash where a relatively minor malfunction led to auto-pilot disconnect and the pilot reacted inappropriately to the situation. Failing gauges in real life are really challenging to understand and react properly.
-
I see 737's have issues with their five(!) pitot tubes as well, going back a few years.
http://aviationweek.com/awin/boeing-addresses-pitot-tube-anomaly-its-737s (http://aviationweek.com/awin/boeing-addresses-pitot-tube-anomaly-its-737s)
I don't understand why heating a pipe is so difficult to engineer, redundancy doesn't help and there are still crashes happening from a corrupted sensor.
Pic "thermal imaging of a partially shorted pitot probe {heater?} shows that heat (red) does not reach the tip, where ice can form and corrupt airspeed measurements". (Credit: Irish Air Accident Investigation Unit)
-
Have not yet enough info on this to get an idea of what would have happened, but I don't agree with the general claim that crashes "happen from a corrupted sensor."
That's sometimes the starting point, but almost never the real cause. Unless the plane is already at a very low altitude (on approach for instance) with low visibility, a bad airspeed indication doesn't itself cause a crash. An experienced pilot knows 1/ how to spot a defective pitot when it happens and 2/ that the best way of dealing with it is usually not to do anything until the measurement gets back to normal. Unfortunately, a lot of airline pilots are not as experienced as they used to be or as they should be, and sometimes they will act irrationally on commands until the plane stalls. That's pretty much what happened with the (in)famous Rio-Paris flight, for instance. The reports are all publicly available.
-
Unconfirmed information suggests this crew was rather experienced.
I had a pitot tube clog on an IFR flight in a single-engine airplane about 10 years ago. The hard part of identifying the problem is that it came on rather slowly. The aircraft only had a single tube, but the pitch, power, altitude, and temp of the aircraft did not agree with the number I was seeing. My reaction was to keep the wings level, the pitch level, and the power constant while I tried to understand what was happening. Once I was pretty sure there was no fixing it - I called ATC to help get me out of the clouds with a very slow decent. All ended well, but much more confusing and intense than my training ever suggested.
The systems in a 737 are massively more complex and I believe they have an automatic reversion when a single system is out of agreement. Even if it does not, the identification and response to a pitot/static error or total failure is among the most rehearsed emergency in my experience. Perhaps less so in the heavy iron aircraft with all the redundancy.
-
Air France 447 was a night flight in heavy rain.
Lion 610 was a morning flight in what appears to have been VFR conditions. Yes, there were clouds, but weather was reported good enough (2000-and-5) that student pilots could have been out soloing airplanes in it. You can't comfortably fly a transport jet solely by visual references, but you ought to be able to keep it out of the water, IMO.
-
I had a pitot tube clog on an IFR flight in a single-engine airplane about 10 years ago. The hard part of identifying the problem is that it came on rather slowly. The aircraft only had a single tube, but the pitch, power, altitude, and temp of the aircraft did not agree with the number I was seeing. My reaction was to keep the wings level, the pitch level, and the power constant while I tried to understand what was happening. Once I was pretty sure there was no fixing it - I called ATC to help get me out of the clouds with a very slow decent. All ended well, but much more confusing and intense than my training ever suggested.
Keep flying the plane in a configuration you know works. That was the experience I was given by two very high time old timers that were my instructors. AFR447 was an example of doing the opposite.
I'm sure we'll find out why this plane went down, but all of the people immediate jumping to conclusions is just silly
-
Have not yet enough info on this to get an idea of what would have happened, but I don't agree with the general claim that crashes "happen from a corrupted sensor."
That's sometimes the starting point, but almost never the real cause. Unless the plane is already at a very low altitude (on approach for instance) with low visibility, a bad airspeed indication doesn't itself cause a crash. An experienced pilot knows 1/ how to spot a defective pitot when it happens and 2/ that the best way of dealing with it is usually not to do anything until the measurement gets back to normal. Unfortunately, a lot of airline pilots are not as experienced as they used to be or as they should be, and sometimes they will act irrationally on commands until the plane stalls. That's pretty much what happened with the (in)famous Rio-Paris flight, for instance. The reports are all publicly available.
Same here: https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1951 (https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1951) and also a Boeing 737 with faulty sensor readings.
-
There's so many pitot tube incidents. I question the airplane's software algorithms, a pitot tube reading wrong seems to generate alarms that confuses the crew and causes a lethal panic. The software should be able to estimate from the other sensors or roll back to GPS for speed, or just stop issuing a fake airspeed if you know the sensors have failed and can't make a concensus.
737
"Three of the probes are on the nose for airspeed measurements—for the pilot, the co-pilot, and as a backup—and two are on the vertical stabilizer for the elevator feel-and-centering unit. If the airspeed difference between the pilot and co-pilot probes is greater than 5 kt. for 5 sec. consecutively, the pilots receive an “IAS (indicated airspeed) Disagree” alert. "
"A man with a watch knows what time it is. A man with two watches is never sure." (https://en.wikipedia.org/wiki/Segal's_law)
You can't take a concensus with two sensors.
So captain and co-pilot are lost as to the airplane's true speed but the backup sensor does nothing?
-
Unconfirmed information suggests this crew was rather experienced.
I had a pitot tube clog on an IFR flight in a single-engine airplane about 10 years ago. The hard part of identifying the problem is that it came on rather slowly. The aircraft only had a single tube, but the pitch, power, altitude, and temp of the aircraft did not agree with the number I was seeing. My reaction was to keep the wings level, the pitch level, and the power constant while I tried to understand what was happening. Once I was pretty sure there was no fixing it - I called ATC to help get me out of the clouds with a very slow decent. All ended well, but much more confusing and intense than my training ever suggested.
The systems in a 737 are massively more complex and I believe they have an automatic reversion when a single system is out of agreement. Even if it does not, the identification and response to a pitot/static error or total failure is among the most rehearsed emergency in my experience. Perhaps less so in the heavy iron aircraft with all the redundancy.
Almost same thing happened to me in 1975 or so. Piper Arrow. Moral is that airspeed, while very important, is not the only indicator of the aircraft's airspeed.
-
This plane was brand new, just entered service in August.
Apparently Lion are considered shit - possibly even worse than Ryanair if that is even possible, like they actually charge budding pilots money to fly their planes instead of paying them!! :palm:
But the pilot of this plane was a pro and had at least 6000 hours flying experience.
Terrible incident for all involved. Damn. We need answers.
-
This plane was brand new, just entered service in August.
Apparently Lion are considered shit - possibly even worse than Ryanair if that is even possible, like they actually charge budding pilots money to fly their planes instead of paying them!! :palm:
But the pilot of this plane was a pro and had at least 6000 hours flying experience.
Terrible incident for all involved. Damn. We need answers.
Sure, just like we got for MH370! Complete disinformation from the authorities who are more interested in their jobs than saving lives.
-
Boeing may be the best source of answers on this one. Since the plane is so new - ALL of Boeings customers and the NTSB are going to be asking a pile of questions.
-
For those interested in this stuff I highly recommend the book QF32
The captain takes you blow by blow through what it's like to get multiple conflicting warnings and whatnot
https://www.amazon.com.au/QF32-author-Life-Lessons-Cockpit-ebook/dp/B007KTLQ5W (https://www.amazon.com.au/QF32-author-Life-Lessons-Cockpit-ebook/dp/B007KTLQ5W)
-
Sure, just like we got for MH370! Complete disinformation from the authorities who are more interested in their jobs than saving lives.
They found the aircraft, so that seems unlikely. The stakes are much too much for it to be brushed under the carpet.
-
... or roll back to GPS for speed, or just stop issuing a fake airspeed if you know the sensors have failed and can't make a concensus.
GPS shows ground speed, not air speed. Not entirely useless, but they're usually not the same number.
The IAS alert will tell the pilots the left and right numbers don't agree. Odds are one of them is correct, so letting the pilots know the readings is still useful. They have airspeed unreliable procedure, which involves turning off the autopilots and putting the plane in a particular power and pitch setting to maintain airspeed, at least until they evaluate the problem.
737
"Three of the probes are on the nose for airspeed measurements—for the pilot, the co-pilot, and as a backup—and two are on the vertical stabilizer for the elevator feel-and-centering unit. If the airspeed difference between the pilot and co-pilot probes is greater than 5 kt. for 5 sec. consecutively, the pilots receive an “IAS (indicated airspeed) Disagree” alert. "
"A man with a watch knows what time it is. A man with two watches is never sure." (https://en.wikipedia.org/wiki/Segal's_law)
You can't take a concensus with two sensors.
So captain and co-pilot are lost as to the airplane's true speed but the backup sensor does nothing?
The aux pilot tube is for the ISFD, the backup flight instrument that's self-contained, including internal backup-power in the event the cockpit goes dark. So that's a third airspeed report available to the pilots.
I suspect we'll find the cause of the crash is something else entirely. They will find the black boxes, so we will know eventually.
-
For those interested in this stuff I highly recommend the book QF32
The captain takes you blow by blow through what it's like to get multiple conflicting warnings and whatnot
https://www.amazon.com.au/QF32-author-Life-Lessons-Cockpit-ebook/dp/B007KTLQ5W (https://www.amazon.com.au/QF32-author-Life-Lessons-Cockpit-ebook/dp/B007KTLQ5W)
Worth watching the episode of "Mayday" about QFA32 too.
https://www.youtube.com/watch?v=1eSiEFDBtvg (https://www.youtube.com/watch?v=1eSiEFDBtvg)
-
There's so many pitot tube incidents.
Yep, especially when the pilots and ground crew on their pre-flight walk arounds can't/don't/won't see the socks placed on them to keep the various mason wasps from building nests in them.
Not all parts of the world have this problem but it's bad enough in some locations that covering the pitot tubes is mandatory but easily overlooked in pre-flight checks. ::)
-
... or roll back to GPS for speed, or just stop issuing a fake airspeed if you know the sensors have failed and can't make a concensus.
GPS shows ground speed, not air speed. Not entirely useless, but they're usually not the same number.
I'm no pilot, but I would suggest GPS speed determination would be pretty much useless unless you know the direction and speed of the winds in your location at your flight level.
-
Yep, especially when the pilots and ground crew on their pre-flight walk arounds can't/don't/won't see the socks placed on them to keep the various mason wasps from building nests in them.
Not all parts of the world have this problem but it's bad enough in some locations that covering the pitot tubes is mandatory but easily overlooked in pre-flight checks. ::)
They should make the covers striped fluorescent pink/orange/glow in the dark green balls that are hard to miss, and designed to tear away at typical flight speeds should one be forgotten.
-
Yep, especially when the pilots and ground crew on their pre-flight walk arounds can't/don't/won't see the socks placed on them to keep the various mason wasps from building nests in them.
Not all parts of the world have this problem but it's bad enough in some locations that covering the pitot tubes is mandatory but easily overlooked in pre-flight checks. ::)
They should make the covers striped fluorescent pink/orange/glow in the dark green balls that are hard to miss, and designed to tear away at typical flight speeds should one be forgotten.
Well they do have ribbons on them but apparently that isn't always enough.
(https://www.aircraftspruce.com/cache/370-320-/catalog/graphics/1/13-02738.jpg)
https://www.aircraftspruce.com/menus/fb/covers_pitot.html (https://www.aircraftspruce.com/menus/fb/covers_pitot.html)
-
Yep anything that must be removed before flight is tagged bright red. This includes inside the cockpit (Small lanes often physically lock the controls so prevent the wind banging the directly connected control surfaces around)
And there have been cases where a pressure sensing port on the side of a plane was covered up with tape to protect it while the plane was washed. But then someone forgot to remove it and nobody noticed it so it caused all sorts of strange readings on the instruments once the plane has taken off.
-
... or roll back to GPS for speed, or just stop issuing a fake airspeed if you know the sensors have failed and can't make a concensus.
GPS shows ground speed, not air speed. Not entirely useless, but they're usually not the same number.
I'm no pilot, but I would suggest GPS speed determination would be pretty much useless unless you know the direction and speed of the winds in your location at your flight level.
That was my point. On the other hand, often one does have at least a ballpark idea of that information, especially when it comes time to land the plane. And ground speed remains useful for navigation purposes.
-
Something really has gone wrong with this flight soon after take off.
Data from https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/ (https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/)
Graph of entire flight altitude/rate of climb
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=559546;image)
Graph of takeoff altitude/rate of climb
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=559552;image)
Flight is not a smooth climb to flight level, altitude and rate of climb are all over the place.
Indicates flight being flown manually.
Graph of last minute of flight altitude/rate of climb
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=559558;image)
This is at what appears on radar maps (and radio comms) to be at the point where the plane was to turn around to return to the airport.
-33,000 ft/minute, no chance of survival.
I think the altitude values don't show the true horror of what occurred
My guess is the plane in fact attempted the turn while descending rapidly, this caused it to roll over and become impossible to recover from.
Various theories about causes, we can rule out engine problems, as planes with no working engines can still fly to some extent.
That just leaves:
A) pilot actions (combined with faulty instrumentation).
B) flight control malfunction or mechanical failure.
A is looking very likely, but B could also be involved or the main cause.
The crash people should be looking at is Air France Flight 447, where inconsistencies between the airspeed measurements were involved.
-
I'm not a pilot and have only rudimentary knowledge about this. Hopefully not too much of a noob question.... but if a Pitot tube or aircraft speed sensor was blocked or malfunctioning, it would tell the pilot the aircraft is going too slow? So wouldn't they speed up the airplane? Wouldn't speeding up help keep it flying in the air? I would imagine the reverse would be worse, where the sensor is telling you that you are going fast and you slow down and stall.
-
I'm not a pilot and have only rudimentary knowledge about this. Hopefully not too much of a noob question.... but if a Pitot tube or aircraft speed sensor was blocked or malfunctioning, it would tell the pilot the aircraft is going too slow? So wouldn't they speed up the airplane? Wouldn't speeding up help keep it flying in the air? I would imagine the reverse would be worse, where the sensor is telling you that you are going fast and you slow down and stall.
The sensors give erratic readings, if one is bad you have to figure out which one it is. They work on air pressure within the sensor tube, the tube could be partially blocked, slow to respond etc.
Lets say there is an unwanted item (dead bug) inside the pitot tube, and it's rolling around inside. Changes in angle/altitude of the plane will give all sorts of crazy readings.
If you have more than one sensor malfunction, it becomes a very tricky task.
Planes fly within an envelope where too fast or too slow results in it falling out of the sky, or at least trying to.
Faster = more lift, climbing too fast results in reduced airspeed, which then results in almost no lift (a stall)
Slower = less lift, descending too slow results in increased airspeed, decreased lift, which then results in inability to climb back up.
If you don't trust the instruments, there are procedures to fly just with particular throttle and stick positions. There is a whole table to look at.
In other words, fly the plane carefully, ask the tower for altitude information on your plane, don't use instruments if you don't believe them.
-
If you are interested how it works when there is an unreliable airspeed situation, here is an explanation from an actual 737 captain:
https://youtu.be/xiB1eejdgdQ?t=489
Basically annoying but, if correctly handled, a non-event. He explains that they even have tables that allow him to fly the plane without any airspeed indicator at all, only using known combination of pitch and power to achieve certain airspeeds (e.g. for landing). Furthermore, most of the procedures for this are memory items (i.e. something the pilot needs to know from memory, without having to rely on a checklist).
So should this happen the pilot flying is supposed to fly pitch and power, wings level. The crew cross-checks the instruments, see that two sets (e.g. backup + first officer's) agree and the third set (captain's) is wrong, the captain hands control over to the first officer and problem solved - exactly what happened on the flight the day before the crash.
And even if all three sets go out there is no reason for the plane to go down unless there is some other problem. Of course, that requires some hand-flying skills because autopilot is of no use in such situation. E.g. there has been an Airbus A330 in Brisbane that took off with the pitot covers still in place. The crew declared emergency and safely returned back to the airport.
I'm not a pilot and have only rudimentary knowledge about this. Hopefully not too much of a noob question.... but if a Pitot tube or aircraft speed sensor was blocked or malfunctioning, it would tell the pilot the aircraft is going too slow? So wouldn't they speed up the airplane? Wouldn't speeding up help keep it flying in the air? I would imagine the reverse would be worse, where the sensor is telling you that you are going fast and you slow down and stall.
When a pitot malfunctions, it could indicate basically anything. Pitot works by comparing the pressure of the oncoming air with pressure from a static port (usually at the bottom of the plane, not facing the airstream) and the airspeed indication is derived from that.
So if e.g. the pitot tube gets clogged you may not get any airspeed data at all (e.g. because someone forgot to remove the covers!), the data between the different tubes could be different (airliners have usually at least 3 pitots - one for captain and one for the first officer + one for the backup instruments), you may get lower than usual speeds if the tube is clogged partially.
Then you can have problems with the static port too. That is much more insidious because that causes a cascade of failures in the cockpit and it is not always immediately apparent what the problem is - you will lose airspeed indication, altimeters will go haywire, also vertical speed indication. Basically anything that depends on atmospheric pressure. There have been several accidents caused by clogged/covered static ports too.
That was my point. On the other hand, often one does have at least a ballpark idea of that information, especially when it comes time to land the plane. And ground speed remains useful for navigation purposes.
You have the ground speed available. However, ground speed is of little use for actually flying the plane - your lift (and thus the ability to stay aloft and not make a smoking crater on the ground) depends on the airspeed (the speed of the plane relative to the air) and not on ground speed.
Worse, the difference between indicated airspeed and ground speed grows the higher you are (and the lower the air pressure is) and also with any wind - if you have ever seen a plane land into a strong headwind by dropping down almost vertically on the runway with little forward movement that is why. The ground speed was low but the airspeed was still sufficient to maintain lift and to not stall (and crash) thanks to the headwind. Also the opposite has happened - e.g. if a plane encounters a strong windshear it could lose enough airspeed that it would stall and crash despite moving fast relative to the ground.
-
I'm not a pilot and have only rudimentary knowledge about this. Hopefully not too much of a noob question.... but if a Pitot tube or aircraft speed sensor was blocked or malfunctioning, it would tell the pilot the aircraft is going too slow? So wouldn't they speed up the airplane? Wouldn't speeding up help keep it flying in the air? I would imagine the reverse would be worse, where the sensor is telling you that you are going fast and you slow down and stall.
Simple. You need two things for Indicated Air Speed, IAS, the ram air dynamic pressure and the static air pressure. Block one or the other and changes in altitude will change your IAS.
Depending on the plane the Pitot tube might have the static port as part of the same structure, in other cases it is a flat hole on the side of the plane.
Had my static port freeze over once in the clouds when I picked up a tad of ice. The Pitot heat had been one for the past hour or more. I pulled a tad of power and started down as I called ATC and told them what I was doing. I only needed about 1000 feet to get into above freezing air. The ice broke loose and the airspeed and altimeter quickly snapped into place. Done a bit more and broke out o the clouds into snow. I knew what MEA and the ceiling so I knew I could breaking to VMC safely. 2 hours after getting the ice, landing in 50F weather and still had ice stuck to wingtip nav lights. It comes on quick and stays put.
One other time, and we had a cover on the Pitot tube while parked, took the plane out, run up, takeoff, altimeter is not right, slow moving, doing odd things. Nice VFR day, just came right around the pattern and landed based on eyes and feel of the plane. Long story short, a spider had partly blocked way up into the static port with eggs.
-
Thanks for the explanations. I assumed like most smaller/simpler airplanes of the past you would just fly based on feel and feedback and what you saw, but that could be difficult at night or bad weather conditions (when you need to rely more on instruments). I guess it is very hard to tell how fast you are going or whether you are going up or dropping when you are far up from the ground. With enough experience in a particular aircraft you would have an intuitive sense of what kind of pitch and engine throttle is needed and when you are low to the ground you may be able to see if it is doing what you want the airplane to do.
With this particular new airplane, with fly-by-wire systems and computers automating a lot of the conditions (and perhaps, if I am to assume correctly, over-riding perhaps pilots in certain situations?) then could this be a case of AI or "smart algorithms" gone wrong? Or are pilots pretty much in control. I know it is too early to assume anything, we still don't know.
-
On a slight side note, it takes next to nothing to receive ADS-B transmissions. I have a Raspberry Pi + $12 USB Software Defined Radio in my garage uploading data to Flightradar24 (and by being a source node, you get full business level access to fr24)
-
As the a not working pitot tube seems to be a rather common problem, the pilots should have regularly seen such a scenario in the simulator during training.
If the standard procedure is as simple as flying by setting power and other settings to a standard value depending on altitude, weight and whatever, I would even expect the auto-pilot to be able to do such a simple calculation / look in the table. At least for the first few seconds to minutes I would prefer this over a sudden turn over to manual control.
Still a lot of speculations to what causes the accident - just wait a few more days to get more info.
-
Thanks for the explanations. I assumed like most smaller/simpler airplanes of the past you would just fly based on feel and feedback and what you saw, but that could be difficult at night or bad weather conditions (when you need to rely more on instruments). I guess it is very hard to tell how fast you are going or whether you are going up or dropping when you are far up from the ground. With enough experience in a particular aircraft you would have an intuitive sense of what kind of pitch and engine throttle is needed and when you are low to the ground you may be able to see if it is doing what you want the airplane to do.
Even low to the ground your sense of airspeed is way off. The problem is we see ground speed. Other factors to into play, for example at night for some reason venting on the ground seems to be going by much faster. But the biggest is that the plane and the wings perform based on IAS, Indicated airspeed, you then have TAS, true airspeed which corrects for air density, and then from that winds give you ground speed. Now estimate IAS to better that +/- 5 knots based on all of that. And even 5 knots fast or slow is not good.
That said, yes once you get good in a model and have been in and out of the same airport a lot, you know I need X power to hold altitude right at the top of the white arc with one notch of flaps. Drop the gear abeam the numbers and touch nothing else, add flaps as you come base and then final. In a PA28-200R that put me setup great for final.
I got a chance to try it by "feel" with a complete electrical failure at night, couldn't see any instruments, no time to reach and grab my flashlight. I was already entering the pattern, just did what I always did hundreds of times. Ended up down with no problems, I suspect maybe was a tad slow. I will say the pucker factor was very high.
-
Looking at Air France flight 447:
"The loss of airspeed indications caused the autopilot, flight director, and autothrust to disconnect, as they require airspeed information to operate. The airplane’s handling characteristics also changed, as the airplane’s fly-by-wire flight controls degraded from its Normal to Alternate law. This led to the loss of many automatic protection mechanisms built into Normal law, including stall protection."
https://risk-engineering.org/concept/AF447-Rio-Paris (https://risk-engineering.org/concept/AF447-Rio-Paris)
-
Looking at Air France flight 447:
"The loss of airspeed indications caused the autopilot, flight director, and autothrust to disconnect, as they require airspeed information to operate. The airplane’s handling characteristics also changed, as the airplane’s fly-by-wire flight controls degraded from its Normal to Alternate law. This led to the loss of many automatic protection mechanisms built into Normal law, including stall protection."
https://risk-engineering.org/concept/AF447-Rio-Paris (https://risk-engineering.org/concept/AF447-Rio-Paris)
Yep.
Adding to this, if you then only have ground speed (GPS) to work with and a 100kt tailwind things won't end well.
-
Yep.
Adding to this, if you then only have ground speed (GPS) to work with and a 100kt tailwind things won't end well.
Pitch + Power = Performance.
Any pilot can get rather close to a target airspeed with a known pitch+power (adjusted for altitude and temp).
The real trick is to understand that the system is in a state of failure and stop flying the airplane based on the potentially erroneous information. Identifying that a problem exists can easily be more challenging than dealing with it.
-
I hope the black boxes survived.
I know they are tough, but it's not unlimited tough, and this was about as fast an impact as you can get. And the water is only approx 30m deep, so it might as well have just hit the ground.
-
I hope the black boxes survived.
I know they are tough, but it's not unlimited tough, and this was about as fast an impact as you can get. And the water is only approx 30m deep, so it might as well have just hit the ground.
At the relevant impact speed, water is pretty damned hard. I doubt that the aircraft impacted the bottom with any kind of significant speed (meaning 30m, 100m, and 500m would be essentially "the same" wrt impact forces).
From another aviation forum that I waste spend a lot of time, aircraft might have impacted ~475 knots TAS and 40° nose down.
-
This thread reminds me of when pilots start discussing electrical engineering on PPRuNe.
This tragic loss of life MAY have been caused by faulty instrument indications which in turn caused the pilots to act inappropriately in some way. Maybe. They clearly struggled with the aircraft for many minutes before finally losing control and diving into the sea at very high speed.
"Unreliable airspeed" is something that airline pilots are supposed to be practicing in simulators regularly. Pitch and power settings to establish a gentle climb at a reasonable airspeed despite faulty indications are supposed to be embedded in the pilot's memory and trained regularly in sim. This flight was in daylight, good visibility and good weather, so nothing at all like AF447. The 737 MAX has mechanical primary flight controls, it is not totally "fly by wire" like Airbus.
Faulty instrument indications could be caused by many things, all of which would have the same outcome, supposedly manageable safely by the crew if they had time, and it appears this crew did have time but didn't manage safely. The case of the B2 at Guam that had the blocked pitot system on takeoff did not allow the pilots enough time to do anything but eject; it was out of control from the moment of liftoff.
-
I hope the black boxes survived.
I know they are tough, but it's not unlimited tough, and this was about as fast an impact as you can get. And the water is only approx 30m deep, so it might as well have just hit the ground.
At the relevant impact speed, water is pretty damned hard.
Yep, I have experience drop testing stuff onto water, it can be as hard as a rock. But it has a lot to do with how surface areas impact etc.
I doubt that the aircraft impacted the bottom with any kind of significant speed (meaning 30m, 100m, and 500m would be essentially "the same" wrt impact forces).
From another aviation forum that I waste spend a lot of time, aircraft might have impacted ~475 knots TAS and 40° nose down.
Possibly. If it was very nose down, then the bottom would have impacted in some way I suspect. But at 40deg that kinda flat-ish in the scheme of thing, so may not have hit bottom in that case.
In any case, it they haven't located the black box by now (which have transponders), then it's likely they are damaged. Although it's also possible the transponder could have sheered off the recorder housing, so they may not be together.
They are located in the tail, so hopefully are just sitting on the bottom somehow instead of buried in the sand.
-
For those interested in this stuff I highly recommend the book QF32
The captain takes you blow by blow through what it's like to get multiple conflicting warnings and whatnot
https://www.amazon.com.au/QF32-author-Life-Lessons-Cockpit-ebook/dp/B007KTLQ5W (https://www.amazon.com.au/QF32-author-Life-Lessons-Cockpit-ebook/dp/B007KTLQ5W)
Better up the ATSB report is like a Agatha Christie multiplied by the Lord of the rings! Hairy, quite close to total death!
Many detailed pictures.
http://www.atsb.gov.au/publications/investigation_reports/2010/aair/ao-2010-089.aspx (http://www.atsb.gov.au/publications/investigation_reports/2010/aair/ao-2010-089.aspx)
-
I have a Raspberry Pi + $12 USB Software Defined Radio in my garage
o you share? I use a proper Equipment for.
-
I have a Raspberry Pi + $12 USB Software Defined Radio in my garage
o you share? I use a proper Equipment for.
I wouldn't mind setting up a receiver, but i can't find a map of existing installations?
-
Not to derail the main thread, but I just noticed this article on CNN and thought :wtf::
https://www.cnn.com/travel/article/electric-easyjet-planes-intl/index.html (https://www.cnn.com/travel/article/electric-easyjet-planes-intl/index.html)
I think it is mostly a marketing strategy the company concocted to get more media coverage, but I am concerned about the 10-15 years timeline they expect these to be viable, tested and practical. I know they have small airplanes on short routes already in operation but is it something that paying passengers are willing to risk? If an electric car fails vs. electric plane, your chances of surviving may vary quite a bit.
We are just on the heels of this 737 tragedy which is a brand new plane, but I don't know the history of electric planes well enough to say if they are as reliable and safe at this point. From a small Cessna-style 2 seater to 9 seater electric with maybe 500km range (short flights) seem to be already on the near horizon, but I can't imagine yet seeing anything like the picture below without a major breakthrough:
(https://dynaimage.cdn.cnn.com/cnn/q_auto,w_1351,c_fill,g_auto,h_760,ar_16:9/http%3A%2F%2Fcdn.cnn.com%2Fcnnnext%2Fdam%2Fassets%2F181030130218-easyjet-wright-electric.jpg)
-
I wouldn't mind setting up a receiver, but i can't find a map of existing installations?
depend on the national law you could end in Jail for but on the other end there are so many People go get them all is impossible.
There arent any Maps because you must/ can/ have to share from IP to IP.
Its like a Black Marked Business you need to know someone to get he Data.
-
Of course, the previous day's problems may have had nothing at all to do with the cause of the accident. It is also possible that knowledge of the previous failure may have misled the aircrew into inappropriate response to the actual failure, whatever that may turn out to be. There is a term for this, I can't remember - getting locked into a wrong interpretation of the situation causing you to disregard evidence (that you are interpreting wrongly).
-
With this particular new airplane, with fly-by-wire systems and computers automating a lot of the conditions (and perhaps, if I am to assume correctly, over-riding perhaps pilots in certain situations?) then could this be a case of AI or "smart algorithms" gone wrong? Or are pilots pretty much in control. I know it is too early to assume anything, we still don't know.
737 is not a fly-by-wire, it has classic flight controls (hydraulics for the most part).
There is also no "AI" or "smart algorithms" overriding the pilots, not even on the Airbuses. The electronics is designed in a way that whenever something seems out of whack, the automation will warn the crew and disconnect, handing the entire mess to the human sitting there to sort out.
What some planes (Airbus, not the crashed 737) have are things like the "alpha floor" protections (it prevents stalling under certain conditions) but these are typically the first ones lost/disabled when the computers detect some kind of anomaly - that's what Airbus refers to as "laws" (normal vs alternate when something is wrong for ex).
And when the pilot feels the automation is doing something it shouldn't for whatever reason, there is a disconnect button on the yoke/sidestick and for the worst case there is always a circuit breaker that can be pulled. Even on the Airbus you can fly the plane without the computers - it is going to be difficult but it is still possible.
Looking at Air France flight 447:
"The loss of airspeed indications caused the autopilot, flight director, and autothrust to disconnect, as they require airspeed information to operate. The airplane’s handling characteristics also changed, as the airplane’s fly-by-wire flight controls degraded from its Normal to Alternate law. This led to the loss of many automatic protection mechanisms built into Normal law, including stall protection."
https://risk-engineering.org/concept/AF447-Rio-Paris (https://risk-engineering.org/concept/AF447-Rio-Paris)
Guys, AF447 is not a comparable situation. AF447 was first and foremost caused by relatively inexperienced crew mishandling the controls in a major way - newer attempting the "pitch and power" stable configuration and causing the plane to stall by keeping pulling at the side stick almost all the way down. The crew has never recognized the stall and never attempted to correct it, despite the warnings and buffet they were feeling. It was also not clear who (if anyone) was actually flying - both crewmen were trying to make control inputs at the same time.
The plane was perfectly flyable the entire time, though. At the time of crash it was flown by two rather inexperienced first officers (captain went to sleep after the departure from Rio, I believe, as it was supposed to be a rather uneventful part of the trip). The failure has also occurred at night, at high altitude and in turbulence. None of that was the case for the Lion Air flight (experienced crew, daytime, low altitude, good weather).
Also, since then a lot of training since the AF447 has been focused on both manual flying and recovery from similar failures (the AF447 pilots except of the captain apparently didn't have any training of dealing with unreliable airspeed in a "manual" plane, both having been trained directly on the Airbus).
Here is the AF447 report:
https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf (https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf)
Given the (few) data we have about the Lion Air flight, it would surprise me if there was any similarity at all to the AF447 flight. The Lion Air crew was obviously not in a stall, they were trying to maintain level flight but ultimately failed.
This entire pitot discussion is very likely a red herring caused by the maintenance log from the day before and there had to be some other major mechanical problem on board (uncontained engine failure, explosion, decompression, whatever) to cause a crash like this. This kind of speculation is pretty pointless until there is more data available, e.g. from the black boxes.
-
This entire pitot discussion is very likely a red herring caused by the maintenance log from the day before and there had to be some other major mechanical problem on board (uncontained engine failure, explosion, decompression, whatever) to cause a crash like this. This kind of speculation is pretty pointless until there is more data available, e.g. from the black boxes.
Something like https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261 ?
-
This entire pitot discussion is very likely a red herring caused by the maintenance log from the day before and there had to be some other major mechanical problem on board (uncontained engine failure, explosion, decompression, whatever) to cause a crash like this. This kind of speculation is pretty pointless until there is more data available, e.g. from the black boxes.
Something like https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261 ?
Flight 261 was an MD83, not a 737, the rudder is driven in a different way. And given that this was a brand new plane, the chance that something has worn out already (in the 261 crash the rudder jackscrew threads were worn off due to poor maintenance) is minimal.
It could be literally anything at this point. Even something like losing the rudder fin or even an entire vertical stabilizer (happened in Japan before bcs of poorly repaired tailstrike - the plane flew for a while before hitting a mountain, also old models of 737, not NG or MAX, had a history of rudder problems). Or an engine blowing up and taking out the hydraulics lines (Sioux City crash landing - landed using differential engine thrust and manual trim because main flight controls were inop). Or a bomb going off. Or even a fight in the cockpit for all we know. I am not saying that any of these are likely but until we know more it is a speculation equally good as any other.
Could it be that the crash was related to a poorly repaired failure from the day before and the crew stuffing it up? Sure. But it could have also been a completely different problem.
So far the only information are rather inaccurate Flightradar data, crew requesting a return to Jakarta (suggesting a mechanical problem on board) and the information that there has been an avionics failure the day before. Nothing else. Trying to conclude anything from only that is a fool's errand.
-
Something like https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261 ?
Flight 261 was an MD83, not a 737, the rudder is driven in a different way. And given that this was a brand new plane, the chance that something has worn out already (in the 261 crash the rudder jackscrew threads were worn off due to poor maintenance) is minimal.
Alaska 261 was a horizontal stabilizer (controls pitch trim) jackscrew issue, not a rudder (controls yaw) defect.
That it is almost surely unrelated is 100% true (other than both flights ending in water with loss of all aboard).
-
There's so many pitot tube incidents.
Yep, especially when the pilots and ground crew on their pre-flight walk arounds can't/don't/won't see the socks placed on them to keep the various mason wasps from building nests in them.
Not all parts of the world have this problem but it's bad enough in some locations that covering the pitot tubes is mandatory but easily overlooked in pre-flight checks. ::)
Worked Avionics Instruments in the USAF late 70's early 80's and we had a couple occasions where we needed to replace a pitot tube because the cover wasn't removed and burned up in-flight. I don't know how that could be missed during takeoff roll as the IAS for that circuit would be AFU. I kind of doubt this crash was due to a covered pitot tube as it should have been obvious pretty early. OTH, the crash did happen shortly after takeoff. The FDR and CVR should clear things up.
Brian
-
Alaska 261 was a horizontal stabilizer (controls pitch trim) jackscrew issue, not a rudder (controls yaw) defect.
That it is almost surely unrelated is 100% true (other than both flights ending in water with loss of all aboard).
Ah right, not sure why I wrote "rudder". D'oh. Thanks for the correction.
-
Latest update from local news by the reporter that on the SAR ship, black box recovered today at 10 am local time, and apparently undamaged, and it was buried under the mud at about 30m from the surface.
The signals were detected at these coordinates S 05 48 48.051 - E 107 07 37.622 and S 05 48 46.545 - E 107 07 38.393.
(https://akcdn.detik.net.id/community/media/visual/2018/11/01/2ad1a972-6560-43a9-a3df-1ec6fedeecaa_169.jpeg?w=780&q=90)
(https://akcdn.detik.net.id/community/media/visual/2018/11/01/8e56e3f3-d424-46a9-bbd4-02729c4660e8_169.jpeg?w=780&q=90)
Transferred into proper & safe container.
(https://akcdn.detik.net.id/community/media/visual/2018/11/01/bb4341e0-dec4-49c6-b495-da4d6e57100e_169.jpeg?w=780&q=90)
-
Latest update from local news by the reporter that on the SAR ship, black box recovered today at 10 am local time, and apparently undamaged, and it was buried under the mud at about 30m from the surface.
I'm surprised the pinger worked under the mud, but then again, 30m of water makes it vastly easier
-
Something like https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261 ?
Flight 261 was an MD83, not a 737, the rudder is driven in a different way. And given that this was a brand new plane, the chance that something has worn out already (in the 261 crash the rudder jackscrew threads were worn off due to poor maintenance) is minimal.
Alaska 261 was a horizontal stabilizer (controls pitch trim) jackscrew issue, not a rudder (controls yaw) defect.
That it is almost surely unrelated is 100% true (other than both flights ending in water with loss of all aboard).
I meant related as in "sudden failure of control surface". The fact that the plane was so new means it could be a manufacturing defect.
Good they recovered the recorders, we should get the answer soon.
-
Scanning the Wikipedia article on the 737 Max...........
https://en.wikipedia.org/wiki/Boeing_737_MAX
Seems to have been / is a lot of pressure to produce as many planes as possible.
"On August 13, 2015, the first 737 MAX fuselage completed assembly at Spirit Aerosystems in Wichita, Kansas, for a test aircraft that would eventually be delivered to launch customer Southwest Airlines.[26] On December 8, 2015, the first 737 MAX—a MAX 8 named "Spirit of Renton"—was rolled out at the Boeing Renton Factory.[27][28]
Because GKN could not produce the titanium honeycomb inner walls for the thrust reversers quickly enough, Boeing switched to a composite part produced by Spirit to deliver 47 MAXs per month in 2017. Spirit supplies 70 percent of the 737 airframe, including the fuselage, thrust reverser, engine pylons, nacelles, and wing leading edges.[29]
A new spar-assembly line with robotic drilling machines should increase throughput by 33 percent. The Electroimpact automated panel assembly line sped up the wing lower-skin assembly by 35 percent.[30] Boeing plans to increase its 737 MAX monthly production rate from 42 planes in 2017 to 57 planes by 2019.[31]
The rate increase strains the production and by August 2018, over 40 unfinished jets were parked in Renton, awaiting parts or engine installation, as CFM engines and Spirit fuselages were delivered late.[32] After parked airplanes peaked at 53 at the beginning of September, Boeing reduced this by nine the following month, as deliveries rose to 61 from 29 in July and 48 in August.[33] "
Interesting if it turns out to be related to manufacturing.
-
The rate increase strains the production and by August 2018, over 40 unfinished jets were parked in Renton, awaiting parts or engine installation, as CFM engines and Spirit fuselages were delivered late.[32] After parked airplanes peaked at 53 at the beginning of September, Boeing reduced this by nine the following month, as deliveries rose to 61 from 29 in July and 48 in August.[33] "
Hard to imagine there's room for 40 unfinished jets at Renton, it's a pretty small airport. There's 27 parked there (all over the airfield) in the Google Sat image; and they're spread out all over the place, not sure where you'd find the room to double that.
-
I'm reading that it's the Flight Data Recorder (there are two 'black boxes' the FDR and the Cockpit Voice Recorder)..
In the past there have been issues with 737 rudders (https://en.wikipedia.org/wiki/Boeing_737_rudder_issues) , but that was completely redesigned with the previous generation of the 73. Until they start looking at what's on that recording, we really wont know.
-
As a Avionics Instruments tech while working in the USAF back in the day the reports from a previous flight that also had a problem shortly after takeoff that cleared and they continued on there flight it's looking to me that rather than a cover on a pitot tube it looks like a fitting in the system maybe lose giving erratic readings but then stabilize later. The pitot static system consists of two lines: the static line that monitor atmospheric pressure used for altitude and vertical velocity, and a ram pressure that's used for indicated airspeed and used in combination with the static pressure and temperature for TAS. I suspect that the static line had a lose fitting and if that's true it's also possible a ram pressure line may also have been lose.
During maintenance of the pitot static system lines are opened to hook up test equipment to provide calibrated pressures to check the altimeters and airspeed indicators for correct readings. Of course, when the tests are done the equipment is disconnected AND the lines must then be reconnected. I've seen it happen where this is done but the fittings are not tightened -- they are snugged up but not immediately tightened so at some point down the road the back off a bit and...
The FDR should reveal this even of the pilots didn't properly identify it.
Brian
-
one of the more trivial reasons for a Pitot failure is an insect stuck in the inlet.
The incoming air then never reaches the heater, icing could occur and the readings are nonsense.
-
one of the more trivial reasons for a Pitot failure is an insect stuck in the inlet.
The incoming air then never reaches the heater, icing could occur and the readings are nonsense.
Yes, that's true, however the previous flight reported similar issues so you would THINK they would do an inspection of the pitot tubes before the next flight.
But, erratic readings could be explained by an inspect or other FOD in the pitot tube.
Again, this should be plainly obvious in the FDR data.
Brian
-
I'm not a pilot and have only rudimentary knowledge about this. Hopefully not too much of a noob question.... but if a Pitot tube or aircraft speed sensor was blocked or malfunctioning, it would tell the pilot the aircraft is going too slow? So wouldn't they speed up the airplane? Wouldn't speeding up help keep it flying in the air? I would imagine the reverse would be worse, where the sensor is telling you that you are going fast and you slow down and stall.
No. The ASI measures the difference in pressure between the pitot and static vents. The pitot pressure would remain as it was before it was blocked, so the instrument would likely read the same regardless of a speed increase or decrease in level flight. Although as you gained altitude the indicated speed would increase due to the reducing pressure on the static side. That's maybe what happened, and lead to a stall.
In fact, for VMC flying anyway, most of the stuff on the instrument panel is eye candy. The one thing you really need is to know your airspeed, as it's hard to judge visually. The rest you can tell with the Mk1 eyeball.
-
Is there no sanity check built into the system for the airspeed indication (other than the duplicated pitots and instruments)?
I would have though that the system ought to be able to combine engine thrust, altitude, attitude, control surface settings, takeoff weight, fuel used etc. to calculate and generate an airspeed display plausibility warning. Maybe even to provide a emergency backup 'estimated' airspeed indication?
-
One would think that after the accident over the Atlantic several years ago, that the pitot tube icing issue would have been solved by installing multiple redundant pitot tubes, as well as multiple redundant everything else. the same thing with the satellite data link. Every multimillion dollar aircraft that flies should have one tied to a pair of redundant GPS receivers, one at the nose and one near the tail. Using the two it should be possible to get the exact position and heading anywhere in the world of every one of those planes, in seconds. They get a very good quality of data simply from GPS of their airspeed. The pitot tubes might be good to have but they should all be looked at at the same time and if any of the readings is wildly divergent, it should be eliminated as such an outlier its almost certainly wrong.
-
Is there no sanity check built into the system for the airspeed indication (other than the duplicated pitots and instruments)?
I would have though that the system ought to be able to combine engine thrust, altitude, attitude, control surface settings, takeoff weight, fuel used etc. to calculate and generate an airspeed display plausibility warning. Maybe even to provide a emergency backup 'estimated' airspeed indication?
Of course there is, and it's been well established in this thread already. If two completely independent systems don't agree on airspeed, the pilots are going to be alerted. If they follow their training, they'll go to pitch and power settings to ensure a proper airspeed, then they can reference the backup instrument for a third independent reading. If there's no consensus, they can fly pitch and power settings all the way to a safe landing.
If machines were good enough to be trusted to do the job all the time, there wouldn't be pilots on board at all.
-
One would think that after the accident over the Atlantic several years ago, that the pitot tube icing issue would have been solved by installing multiple redundant pitot tubes, as well as multiple redundant everything else. the same thing with the satellite data link. Every multimillion dollar aircraft that flies should have one tied to a pair of redundant GPS receivers, one at the nose and one near the tail. Using the two it should be possible to get the exact position and heading anywhere in the world of every one of those planes, in seconds. They get a very good quality of data simply from GPS of their airspeed. The pitot tubes might be good to have but they should all be looked at at the same time and if any of the readings is wildly divergent, it should be eliminated as such an outlier its almost certainly wrong.
GPS doesn't give airspeed, it gives ground speed. Great for navigation, but very inaccurate as an airspeed replacement. Could differ by as much as 250mph if the plane is in a jet stream.
-
One would think that after the accident over the Atlantic several years ago, that the pitot tube icing issue would have been solved by installing multiple redundant pitot tubes, as well as multiple redundant everything else. the same thing with the satellite data link. Every multimillion dollar aircraft that flies should have one tied to a pair of redundant GPS receivers, one at the nose and one near the tail. Using the two it should be possible to get the exact position and heading anywhere in the world of every one of those planes, in seconds. They get a very good quality of data simply from GPS of their airspeed. The pitot tubes might be good to have but they should all be looked at at the same time and if any of the readings is wildly divergent, it should be eliminated as such an outlier its almost certainly wrong.
GPS derived ground speed means shit for flying a plane, you need airspeed which can be influenced by prevailing winds that could be all over the place at different altitudes.
-
Is there no sanity check built into the system for the airspeed indication (other than the duplicated pitots and instruments)?
I would have though that the system ought to be able to combine engine thrust, altitude, attitude, control surface settings, takeoff weight, fuel used etc. to calculate and generate an airspeed display plausibility warning. Maybe even to provide a emergency backup 'estimated' airspeed indication?
Of course there is, and it's been well established in this thread already. If two completely independent systems don't agree on airspeed, the pilots are going to be alerted. If they follow their training, they'll go to pitch and power settings to ensure a proper airspeed, then they can reference the backup instrument for a third independent reading. If there's no consensus, they can fly pitch and power settings all the way to a safe landing.
If machines were good enough to be trusted to do the job all the time, there wouldn't be pilots on board at all.
So there's a nice big indicator saying one or both of your airspeed indications may be implausible, without relying on the pilots constantly visually cross-checking their indicators?
Edit: Sorry, I missed the reference to a third, backup, instrument. Is that Pitot too?... and is it linked into the automatic comparison warning too?
-
I bet!
the speed of the gulf stream etc, adds a substantial boost/slow down to planes flying in it, you can see that happening when they change their heading in relation to it.
GPS derived ground speed means shit for flying a plane, you need airspeed which can be influenced by prevailing winds that could be all over the place at different altitudes.
Multiple, heated pitot tubes would be good, I wonder what other kinds of air speed sensors exist.
Anything mechanical that I can think of right now at least, besides a pitot pressure indicator would likely fail at a typical jets speed though.
-
Multiple, heated pitot tubes would be good, I wonder what other kinds of air speed sensors exist.
Anything mechanical that I can think of right now at least, besides a pitot pressure indicator would likely fail at a typical jets speed though.
Mechanical measures aren't completely infeasible. A small propeller device is deployed when all engines and the APU fail to power the bare essentials. This device is obviously capable of dealing with fairly substantial forces, even though a gliding jet liner will be slower than at cruising speeds.
-
I bet!
the speed of the gulf stream etc, adds a substantial boost/slow down to planes flying in it, you can see that happening when they change their heading in relation to it.
GPS derived ground speed means shit for flying a plane, you need airspeed which can be influenced by prevailing winds that could be all over the place at different altitudes.
Multiple, heated pitot tubes would be good, I wonder what other kinds of air speed sensors exist.
Anything mechanical that I can think of right now at least, besides a pitot pressure indicator would likely fail at a typical jets speed though.
When I took my flying lessons (AS350B3) the procedure for a suspect Pitot was to fly a circle and to look at the difference of TAS and ground speed.
-
here a link to an Austrian website (English) discussing crashes & accidents..
http://avherald.com/h?article=4bf90724&opt=0 (http://avherald.com/h?article=4bf90724&opt=0)
-
When I took my flying lessons (AS350B3) the procedure for a suspect Pitot was to fly a circle and to look at the difference of TAS and ground speed.
Perfectly reasonable for a helicopter, for which low airspeed by itself typically isn't an emergency. Maneuvers that cause low rotor speeds/blade stall are the real killers, as I understand it. Not that I've had any rotor training.
-
When I took my flying lessons (AS350B3) the procedure for a suspect Pitot was to fly a circle and to look at the difference of TAS and ground speed.
Perfectly reasonable for a helicopter, for which low airspeed by itself typically isn't an emergency. Maneuvers that cause low rotor speeds/blade stall are the real killers, as I understand it. Not that I've had any rotor training.
You would run this maneuvre at a medium power setting (80% MCP) and a level flight, and try a 2 minutes turn. Bank angle should be very moderate then.
-
Lion Air sent engineer on board fatal flight as ‘anticipatory measure’
https://thewest.com.au/news/aviation/lion-air-sent-engineer-on-board-fatal-flight-in-anticipatory-measure-ng-b881011084z
-
Surprised at how intact the black box is, pinger still attached:
(https://cdn.newsapi.com.au/image/v1/76f362b38beebd6b3e7b79540873d024?width=1024)
-
Then again the black box is a solid metal block. Crashes on land are probably harder for it, especially if the impact is something like straight into a mountain, topped off with the fuel catching fire.
Also why are they called black boxes if they are never actually painted black?
-
Press is saying the flight data recorder is damaged or needs parts for repair or it was found in deep water. Load of bollocks.
A few professionals speculating the airplane was going around 600MPH at impact, explaining why it basically shattered into pieces. This is using the FlightData numbers and it would have to be nose down with engine power to get that fast.
old Boeing article: (http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/s01txt.html)
"Beginning in 1965, FDRs (commonly known as "black boxes") were required to be painted bright orange or bright yellow, making them easier to locate at a crash site. "
15GB for a 787 flight, 1,675 sensors 0.2-20Hz. (https://conf.slac.stanford.edu/xldb2018/sites/xldb2018.conf.slac.stanford.edu/files/Tues_15.50%20Ian%20Willson%20XLDB%202018%20Boeing%20IOT.pdf)
-
If they were going 600mph at impact something else has to be going on -- they never got that high so unless they did a powered dive at high angle it's hard to see how they could have been going that fast. At this point I'm beginning to wonder if maybe the CVR won't be more telling.
Brian
-
The FDR is still very intact because it would've had the whole length of the plane to decelerate (probably while punching through materials softer than it) as it hit the water, so the G forces it experienced weren't that high.
On the other hand, everything in the nose is probably crushed beyond recognition.
-
600mph
a What?! :palm:
-
Knots (https://en.wikipedia.org/wiki/Knot_(unit)) are not SI and not far from MPH as a layman's comparison I guess. American aerospace people were doing the speed numbers.
OK FDR is totally ripped off the base with power supply and I/O, all they pulled is the 'crash survivable memory unit' out of the water?
That seems very strange to have all the metal nicely ripped off, leaving a more or less handheld FDR for press pictures. Those divers must use tin snips :o
Lion Air possibly chose the L3 tech FDR FA2100.
-
It ripped off the base sheet, probably part of the design to reduce the impact on the inner memory stack. That it is all nice and intact with the pinger is not a surprise, it is designed to do that.
-
If they were going 600mph at impact something else has to be going on --
33,000 ft/min = 167 meters/second = 600 kilometers/hour = 375 miles/hour. Someone got their numbers and units mixed up.
-
Did the accident happen during a storm or unusual weather of any kind?
-
Did the accident happen during a storm or unusual weather of any kind?
It's on the first page somewhere near the top.
-
If they were going 600mph at impact something else has to be going on --
33,000 ft/min = 167 meters/second = 600 kilometers/hour = 375 miles/hour. Someone got their numbers and units mixed up.
I believe it was 31K fpm vertical velocity and something like 360 knots of ground speed (horizontal velocity).
Solves to something around 475 knots (about 550 mph) 40° below horizontal.
-
Kill me for starting with Bloomberg numbers (https://www.bloomberg.com/news/articles/2018-11-03/lion-air-jet-s-final-plunge-may-have-reached-600-miles-per-hour) supposedly backed up by:
Expert 1: "Scott Dunham, a former National Transportation Safety Board investigator, who combined the distance the plane traveled horizontally and vertically to arrive at a speed estimate." {600mph}
Expert 2: "John Hansman, a Massachusetts Institute of Technology aeronautics and astronautics professor, estimated the plane was flying at 540mph in the final moments..."
Expert 3: Jasenka Rakas, a lecturer in engineering and aviation at the University of California at Berkeley "...the speed could have been between 586 and 633 mph."
added Bloomberg hype? "At the end, it fell 1,025ft in 1.6 seconds."
I thought the ~600mph was vector sum of vertical and horizontal velocities.
Flightradar24 data (https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/) looking at timestamps, it was at 28,000ft and took minutes to drop, so -33,000ft/min seems wrong too.
2018-10-28 23:31:56Z.030 last two samples do say it fell 1,025ft in 1.6 seconds.
edit: confused flight JT610 with JT43.
-
600mph
a What?! :palm:
Almost breaking the sound barrier! :-DD
-
Flightradar24 data (https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/) looking at timestamps, it was at 28,000ft and took minutes to drop, so -33,000ft/min seems wrong too.
You're confusing the data for the prior flight with that of the fatal flight. On it's last flight, it never got much over 6000 ft.
-
Flightradar24 data (https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/) looking at timestamps, it was at 28,000ft and took minutes to drop, so -33,000ft/min seems wrong too.
You're confusing the data for the prior flight with that of the fatal flight. On it's last flight, it never got much over 6000 ft.
Fixed, it is 1,025ft in 1.6 seconds at the end.
-
Why not put some SD Cards across the Aircraft when the Crash the have some additional infos when the get found.
-
Kill me for starting with Bloomberg numbers (https://www.bloomberg.com/news/articles/2018-11-03/lion-air-jet-s-final-plunge-may-have-reached-600-miles-per-hour) supposedly backed up by:
Expert 1: "Scott Dunham, a former National Transportation Safety Board investigator, who combined the distance the plane traveled horizontally and vertically to arrive at a speed estimate." {600mph}
Expert 2: "John Hansman, a Massachusetts Institute of Technology aeronautics and astronautics professor, estimated the plane was flying at 540mph in the final moments..."
Expert 3: Jasenka Rakas, a lecturer in engineering and aviation at the University of California at Berkeley "...the speed could have been between 586 and 633 mph."
added Bloomberg hype? "At the end, it fell 1,025ft in 1.6 seconds."
Ah yes, Bloomberg, the well known purveyor of fake news. I wouldn't trust them to tell me the right time. :palm:
-
480mph
https://www.youtube.com/watch?v=zPe-bKIid8w (https://www.youtube.com/watch?v=zPe-bKIid8w)
-
Apparently the plane had airspeed indicator problems on its final FOUR flights! Surely enough opportunities for someone to check the pitot tubes and do some sort of investigation? :-\
https://www.bbc.co.uk/news/world-asia-46094495 (https://www.bbc.co.uk/news/world-asia-46094495)
-
Well they do have ribbons on them but apparently that isn't always enough.
Why not some kind of lockout/tagout system then? Put a code in the box which requires keys from all the tags to open (or a bolt cutter for eventualities) and which needs to be transmitted to the pilot.
-
Well they do have ribbons on them but apparently that isn't always enough.
Why not some kind of lockout/tagout system then? Put a code in the box which requires keys from all the tags to open (or a bolt cutter for eventualities) and which needs to be transmitted to the pilot.
Yes it certainly wouldn't be hard to add some sort of fail-safe system so that pilots had live info on their displays on the status of pitot condoms.
Even near proximity RFID tags linked to the flight systems so the aircraft couldn't taxi under its own power would eliminate all stuff ups.
Ain't hard, only the willingness to do so is. :palm:
-
Even near proximity RFID tags linked to the flight systems so the aircraft couldn't taxi under its own power would eliminate all stuff ups.
Ain't hard, only the willingness to do so is. :palm:
Not so easy. The manufacturer has to certify that this mechanism will not be a hazard, e.g. will never disable the aircraft during normal operation.
-
Even near proximity RFID tags linked to the flight systems so the aircraft couldn't taxi under its own power would eliminate all stuff ups.
Ain't hard, only the willingness to do so is. :palm:
Not so easy. The manufacturer has to certify that this mechanism will not be a hazard, e.g. will never disable the aircraft during normal operation.
Yer what ? ? ?
No different to any other sensor or system code in the modern aircraft !
-
They are also not easy, but a device that can disable the aircraft (even designed to do it) is something else. Can you guarantee that these RFID sensors can't fail and disable the aircraft during takeoff, cruise or landing?
What is worse; a failed pitot tube or one sensor that disables the aircraft?
-
Aircraft manufacturers have probably figured pitot safety out better than random EE enthusiasts brainstorming here.
There's an airspeed alive callout and an 80-knot cross-check to catch gross pitot errors. It's extremely unlikely that this airplane took off with pitot covers installed (if that's the case, RFID tagged covers are a non-solution).
They have the FDR; they can hear roughly where the CVR is and are likely to recover it. That will tell a lot more than all the internet speculation combined.
-
Apparently the plane had airspeed indicator problems on its final FOUR flights! Surely enough opportunities for someone to check the pitot tubes and do some sort of investigation? :-\
https://www.bbc.co.uk/news/world-asia-46094495 (https://www.bbc.co.uk/news/world-asia-46094495)
Not looking good for Lion Air, sadly it looks like the techs are going to take the fall even though you can bet it was management saying 'no delays, keep flying'.
So. the two most likely causes appear to me to be either debris (insect etc) clogging the pitot tube or a leak (lose fittings) in the pitot-static system. Of the two I suspect the later is more likely given the fact that the problem came and went on previous flights which I'd argue is less likely to happen with a clog than with a lose fitting.
Brian
-
Aircraft manufacturers have probably figured pitot safety out better than random EE enthusiasts brainstorming here.
There's an airspeed alive callout and an 80-knot cross-check to catch gross pitot errors. It's extremely unlikely that this airplane took off with pitot covers installed (if that's the case, RFID tagged covers are a non-solution).
They have the FDR; they can hear roughly where the CVR is and are likely to recover it. That will tell a lot more than all the internet speculation combined.
I think pitot covers are completely ruled out as that would be glaringly obvious even if it was missed on the first flight with the problem -- how likely is it that they'd miss a pitot cover on four flights in a row? It is possible a cover may have been on during the first flight and they chose to attempt to clean/repair the pitot tube rather than replace it. Again, I think that's very unlikely.
Brian
-
Not so easy. The manufacturer has to certify that this mechanism will not be a hazard, e.g. will never disable the aircraft during normal operation.
Lockout/tagout would make no functional change to the plane though, you just tie a key to the cap.
-
Apparently the plane had airspeed indicator problems on its final FOUR flights! Surely enough opportunities for someone to check the pitot tubes and do some sort of investigation? :-\
https://www.bbc.co.uk/news/world-asia-46094495 (https://www.bbc.co.uk/news/world-asia-46094495)
Not looking good for Lion Air, sadly it looks like the techs are going to take the fall even though you can bet it was management saying 'no delays, keep flying'.
I'm not trying to be flippant here, but the flight crew already took the fall and is likely to take the fall in the official findings as well.
This probably will not get an NTSB report due to where it happened (outside US and non-N carrier), but if it were an NTSB report, it would likely read:
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot's loss of airplane control due to spatial disorientation during the initial climb after takeoff in day visual meteorological conditions.
Contributing factors to the accident were confusing PFD displays due to unreliable airspeed measurements from the pitot-static systems, broken/layered clouds over water, providing a difficult horizon to use as an alternate visual reference for orientation. Additional factors in the accident were flat morning light conditions and inadequately addressed maintenance squawks on prior flights of the pitot-static system.
It's hard to say exactly what they're going to find, but the probable cause is almost certain to start with "The pilot's loss of control..."
-
Pitch + Power = Performance.
Any pilot can get rather close to a target airspeed with a known pitch+power (adjusted for altitude and temp).
I'm coming to this thread pretty late, but this is the whole ball of wax right here. I don't fly big iron, but the the laws of physics are the same for them as anybody else. The AF447 crew screwed up. If it was a pitot problem, this crew screwed up, too. The plane is flyable without IAS.
In fact, in the AF447 situation where all the plane's automatic systems punted, that was (and probably remains) a design defect IMO, because the computers hand the airplane back to the captain at the worse possible moment. A better approach would be for the computer itself to start flying the aircraft by attitude and notify the pilot accordingly.
-
Aircraft manufacturers have probably figured pitot safety out better than random EE enthusiasts brainstorming here.
I'm not random.
-
Not so easy. The manufacturer has to certify that this mechanism will not be a hazard, e.g. will never disable the aircraft during normal operation.
Lockout/tagout would make no functional change to the plane though, you just tie a key to the cap.
I was going to say the ignition key and then post the ignition key from Airplane II but I couldn't find a clip of it.
seems like they could just put a string on the tube cover and have a little suction cup on the other end that sticks to the front window of the airplane.
-
So. the two most likely causes appear to me to be either debris (insect etc) clogging the pitot tube or a leak (lose fittings) in the pitot-static system. Of the two I suspect the later is more likely given the fact that the problem came and went on previous flights which I'd argue is less likely to happen with a clog than with a lose fitting.
Brian
Yes, insects nesting in pitot tubes have caused crashes before and they cant bee seen by external visual check i heard.
-
sounds like they need a way to divert the jet engine thrust into the tube for a second to clear it.
-
sounds like they need a way to divert the jet engine thrust into the tube for a second to clear it.
The pitot tubes are generally up front by the nose on multi-engine aircraft. They need to be in undisturbed air to sense properly.
They're nowhere near the engines and a blast of jet engine thrust would only serve to destroy the tubing and sensors behind. (The system measures the stagnation pressure and relates that back to airspeed. That stagnation sensing loop is closed [or very nearly closed].)
-
https://patents.google.com/patent/US3380298
"Device for purging pitot tubes" patented 1968-04-30. Essentially a valve that can disconnect the sensors and then connect the pitot to a compressed air source to blow out any obstructions from behind. Do planes have something similar?
-
https://patents.google.com/patent/US3380298
"Device for purging pitot tubes" patented 1968-04-30. Essentially a valve that can disconnect the sensors and then connect the pitot to a compressed air source to blow out any obstructions from behind. Do planes have something similar?
I don't think any such devise has been employed outside of testing. Here's the concern... First, it may not work and second, if anything goes wrong you could destroy a lot of expensive avionics. Also, such a devise would be limited to ground use and could never be trusted in-flight. A competent service technician or team of such would know what to do to isolate the problem and fix it -- this happens ALL THE TIME! I suspect the ground crew were told they have 30 minutes before the next flight and if it isn't fixed before then they'd fly just as they did the previous three flights with the problem. A bit like NASA being pressured to launch the Challenger because they wanted there teacher in space.
Brian
-
https://patents.google.com/patent/US3380298
"Device for purging pitot tubes" patented 1968-04-30. Essentially a valve that can disconnect the sensors and then connect the pitot to a compressed air source to blow out any obstructions from behind. Do planes have something similar?
someone should patent this for cleaning pilot tubes
(https://images.prod.meredith.com/product/3c5286530722e9bcc6c69ac524bbe39b/1524025801742/l/yoassi-16-long-bottle-brush-cleaner-tube-bottle-washing-brush-for-washing-baby-bottle-water-bottles-mugs-wine-stemware-narrow-neck-brewing-bottles)
-
Boeing and FAA to issue advice to airlines on 737 Max jets AoA sensor.
"potentially suspect flight-control software that can confuse pilots and lead to a steep descent of the affected aircraft model"
https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339 (https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339)
-
Boeing and FAA to issue advice to airlines on 737 Max jets AoA sensor.
"potentially suspect flight-control software that can confuse pilots and lead to a steep descent of the affected aircraft model"
https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339 (https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339)
That sounds like it's ultimately going to be pilot error.
-
https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339 (https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339)
Paywall :--
-
https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339 (https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339)
Paywall :--
Worked here.
-
Worked here.
Strange...
-
Googling "Boeing Issues Safety Alert Following Lion Air Crash" did the trick for me.
-
https://www.abc.net.au/news/2018-11-08/lion-air-flight-had-crucial-sensor-replaced-prior-to-fatal-crash/10475468 (https://www.abc.net.au/news/2018-11-08/lion-air-flight-had-crucial-sensor-replaced-prior-to-fatal-crash/10475468)
A crucial sensor that is the subject of a Boeing safety bulletin was replaced on a Lion Air jet the day before it plunged into the Java Sea and possibly worsened other problems with the plane, Indonesian investigators have revealed.
Indonesia's National Transportation Safety Committee (NTSC) said it had agreed with Boeing on procedures that the airplane manufacturer should distribute globally on how flight crews can deal with "angle of attack" sensor problems following the October 29 crash that killed all 189 people on board.
Experts say the angle of attack is a crucial parameter that helps the aircraft's computers understand whether its nose is too high relative to the current of air.
The sensor keeps track of the angle of the aircraft nose relative to oncoming air to prevent the plane from stalling and diving.
But a Boeing statement said a safety bulletin, sent to airlines this week, directs flight crews to existing guidelines on how they should respond to erroneous "angle of attack" data.
"The point is that after the AOA [sensor] is replaced the problem is not solved, but the problem might even increase. Is this fatal? NTSC wants to explore this," he said.
So in other words, simply replacing the sensor can not only not work, but can make the problem worse.
I assume as you then have an un-calibrated sensor.
Transport safety committee chairman Soerjanto Tjahjono said airspeed indicator malfunctions on the jet's last four flights, which were revealed by an analysis of the flight data recorder, were intertwined with the sensor issue.
So they have bad readings from both the Angle of Attack and Airspeed sensors, this sounds more like a wiring/electronics issue to me.
-
Boeing jet crashed in Indonesia a day after key sensor replaced
"Lion Air's first two attempts to address the airspeed indicator problem didn't work and for the Boeing 737 MAX 8 plane's second to last flight on Oct. 28, the angle of attack sensors were replaced, Tjahjono said.
On that flight, from Bali to Jakarta, the pilot's and copilot's sensors disagreed. The 2-month-old plane went into a sudden dive minutes after takeoff, which the pilots were able to recover from. They decided to fly on to Jakarta at a lower than normal altitude."
https://komonews.com/news/nation-world/boeing-jet-crashed-in-indonesia-a-day-after-key-sensor-replaced
-
Boeing and FAA to issue advice to airlines on 737 Max jets AoA sensor.
"potentially suspect flight-control software that can confuse pilots and lead to a steep descent of the affected aircraft model"
https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339 (https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339)
That sounds like it's ultimately going to be pilot error.
Well, sure, but it all depends on how far back you go to "ultimately". Myself, I'd say that the major pilot error was to accept the aircraft for flight in the first place, after maintenance on the sensor system. Let a test pilot crew test such critical systems without pax on board first!
But once off the ground, the situation is something like this: you are driving along, fat dumb and happy, at night on a smoothly paved road. Suddenly the pavement ends and you are bouncing along on ruts and potholes, and suddenly a thunderstorm starts dumping hail on you, and your windshield wipers short out, your headlights fail and your horn inexplicably starts blaring. Right at that moment a kangaroo leaps out onto what's left of the road, your brakes fail and you run into it, destroying your vehicle and killing all on board. Ultimately... it's driver error, for not avoiding the 'roo. Innit?
I am not disagreeing though. The pilots evidently did not perform the correct actions for dealing with unreliable air data, therefore "pilot error", but you really have to consider the environment and the demands of the task at hand. The "roo in the road" above doesn't even come close to the disorientation and distractions that must have been happening in that cockpit.
-
That sounds like it's ultimately going to be pilot error.
Well, sure, but it all depends on how far back you go to "ultimately". Myself, I'd say that the major pilot error was to accept the aircraft for flight in the first place, after maintenance on the sensor system. Let a test pilot crew test such critical systems without pax on board first!
You seriously believe that airliners are commonly flown by test pilots without pax after maintenance items? No way that happens after minor maintenance. It gets a signoff from maintenance and the next flight has pax on board. Ultimately, it's the crew's discretion whether or not to take an aircraft, but not taking an aircraft because maintenance was just performed is a short road to unemployment at an air carrier.But once off the ground, the situation is something like this: you are driving along, fat dumb and happy, at night on a smoothly paved road. Suddenly the pavement ends and you are bouncing along on ruts and potholes, and suddenly a thunderstorm starts dumping hail on you, and your windshield wipers short out, your headlights fail and your horn inexplicably starts blaring. Right at that moment a kangaroo leaps out onto what's left of the road, your brakes fail and you run into it, destroying your vehicle and killing all on board. Ultimately... it's driver error, for not avoiding the 'roo. Innit?
I am not disagreeing though. The pilots evidently did not perform the correct actions for dealing with unreliable air data, therefore "pilot error", but you really have to consider the environment and the demands of the task at hand. The "roo in the road" above doesn't even come close to the disorientation and distractions that must have been happening in that cockpit.
That is a pretty reasonable description of the hand that the Air France 447 crew was handed (and that they were unable to handle).
Lion Air was a daytime flight, with largely visual conditions prevailing. I'm going to fully withhold judgment until more information (including CVR transcripts) is available, but based on the information available, this seems a lot closer to "speedometer was covered up by a piece of paper fluttering around the cabin and operator couldn't keep the car between 40 and 80 mph without that reference" than the scenario you describe (which I'd argue was still salvageable by fully-qualified crew, on an average day, but not by that crew on that evening).
-
A new player in this crash is the AOA indicator, or more accurately, the AOA probe. For some reason the AOA transmitter was replaced and I'm kind of wondering how this relates to the pitot/static system. The AOA indicator should indicate the angle the aircraft is flying relative to the air they're flying in and if the new transmitter was not installed properly it could give an erroneous AOA indication.
Additionally, since they appear to have been flying with autopilot the flight control outputs would have been determined by the flight computer taking into account the data from the sensors. It appears that there maybe an issue in the software as it relates to the AOA sensor data and on a previous flight the plane went into a dive that the pilots were able to recover from. Ultimately, with as many issues as they had in the previous flights it is unacceptable that the plane remained in service until the problem was nailed down.
So, the lawyers will have a field day with everyone to blame. The pilots, the ground crew, the airline management, and Boeing. I can well imagine a bunch of lawyers are at this very moment placing orders for new cars and a second home.
Brian
-
AOA seems to be a second pressure port on the pitot probe. One for airspeed, another for critical (stall) angle.
There is a cal file specific to the aircraft. I'm not sure if it was a generic pitot part that was swapped out and cal file left alone or corrupted...
How was the autopilot working for the previous flights?
With a pitot discrepancy, Airbus goes to manual mode.
It seems odd previous flights had issues after takeoff and somehow did fine afterwards.
There are billions of dollars at stake here, I doubt the blame will be proper between parties.
-
Time for a AirFrance thread reminder, so whatever potentially disastrous during flight always:
1:Aviate , 2:Navigate , 3:Communicate. Also for pilots taking off is optional, landing is mandatory.
Just sayin!
-
Lion Air was a daytime flight, with largely visual conditions prevailing. I'm going to fully withhold judgment until more information (including CVR transcripts) is available, but based on the information available, this seems a lot closer to "speedometer was covered up by a piece of paper fluttering around the cabin and operator couldn't keep the car between 40 and 80 mph without that reference" than the scenario you describe (which I'd argue was still salvageable by fully-qualified crew, on an average day, but not by that crew on that evening).
At this stage that's my guess too (with my obvious in-depth knowledge of aviation with one flight and 3hrs flying time under my belt ::) ).
No bad weather, daytime, maybe some clouds making horizon reference a bit tricky, but with no actual fault in the plane control systems, it should have been work-aroundable and completely flyable.
But of course one small thing can often send you down a path that doesn't end well.
They did report issues and were returning to the airport at the time of the incident, so should have been in super-alert troubleshooting mode fresh into the lfight, and not half way across the atlantic 8 hours in and tired and shit suddenly hits the fan.
-
Lion Air was a daytime flight, with largely visual conditions prevailing. I'm going to fully withhold judgment until more information (including CVR transcripts) is available, but based on the information available, this seems a lot closer to "speedometer was covered up by a piece of paper fluttering around the cabin and operator couldn't keep the car between 40 and 80 mph without that reference" than the scenario you describe (which I'd argue was still salvageable by fully-qualified crew, on an average day, but not by that crew on that evening).
At this stage that's my guess too (with my obvious in-depth knowledge of aviation with one flight and 3hrs flying time under my belt ::) ).
No bad weather, daytime, maybe some clouds making horizon reference a bit tricky, but with no actual fault in the plane control systems, it should have been work-aroundable and completely flyable.
But of course one small thing can often send you down a path that doesn't end well.
They did report issues and were returning to the airport at the time of the incident, so should have been in super-alert troubleshooting mode fresh into the lfight, and not half way across the atlantic 8 hours in and tired and shit suddenly hits the fan.
Modern commercial fly by wire AC don't let the pilot have full control even when the autopilot is disengaged. The AOA factor is critical and I expect Boeing will be releasing updated flight control software sometime in the not too distant future.
In order for a pilot to override the control decisions of the computer the pilots must deactivate a number of systems and until they do this the computer is still in charge.
Beyond what I've already posted on this I think what Boeing did today was the first step in addressing an actual control problem that can occur when the right, or wrong, set of airspeed, altitude and AOA data is presented to the computer. The fact that the previous flight had pretty similar problems, issued a Pan-Pan and asked to return, but then the problem went away and they decided to continue with the flight would not be permitted most places in the world but Lion Air appears to operate with the schedule being more important than safety.
There are many at fault here and the consequence is going to be expensive.
Brian
-
However, the Boeing 737 is NOT a fly-by-wire aircraft.
-
1:Aviate , 2:Navigate , 3:Communicate.
4: M....bate.
Though if you are flying a Dalek mothership you may have more success with:
1:Aviate , 2:Navigate , 3:Exterminate 4: Communicate.
Than with 3 and 4 in conventional order. By which time The Doctor has gotten away.
-
The fact that the previous flight had pretty similar problems, issued a Pan-Pan and asked to return, but then the problem went away and they decided to continue with the flight would not be permitted most places in the world but Lion Air appears to operate with the schedule being more important than safety.
The captain/pilot-in-command has significant discretion as to the conduct of the flight. I can think of several valid reasons a flight may initially decide they need to return only to overcome the problem and elect to continue. A mis-programmed FMS/FD may very well give the crew reason for concern and then the crew may overcome that and safely continue the flight. Weather is another. An abnormal or emergency may crop up that is subsequently remedied by reference to the QRH/checklist procedures. Continuing may very well be the safest (or equally safe and more economical) choice.
BA268 is a classic example of that. They lost an engine (with external flames) 300 feet into the climb off LAX en route to Heathrow. ATC declared an emergency on their behalf (also permitted by their job orders (https://www.faa.gov/documentLibrary/media/Order/7110.65X_ATC_w_chg_1_and_chg_2.pdf) (section 10-1)). Crew shut the engine down, continued the climb, and did an assessment to continue the flight rather than dump fuel and return. Passing the east coast of the US, another assessment by them allowed them to continue for England. Ultimately, crew declared an emergency for fuel and landed in Manchester, short of Heathrow.
The first actual section of Federal law governing aviation in the US is 14 CFR 91.3 (https://www.law.cornell.edu/cfr/text/14/91.3), which reads:
§ 91.3 Responsibility and authority of the pilot in command.
(a) The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.
(b) In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.
(c) Each pilot in command who deviates from a rule under paragraph (b) of this section shall, upon the request of the Administrator, send a written report of that deviation to the Administrator.
Airline Ops are additionally governed by part 121, which includes 14 CFR 121.557 (https://www.law.cornell.edu/cfr/text/14/121.557), with substantially similar text. Of course there is pressure in the airline world to complete trips as planned. Because the pilots are generally the first ones to arrive at the scene of the crash, there's also a high degree of pressure to complete flights safely.
-
"Ultimately, crew declared an emergency for fuel and landed in Manchester, short of Heathrow."
Which underlines that in aviation, once you are in an unfamiliar situation you may encounter other unfamiliar situations. In this case an increased fuel burn.
-
The AOS sensor sounds harmless.
But it is not.
As I've learned, the AOS sensor controls the trim system of the aircraft.
The trim system of the aircraft sounds harmless.
But it is not.
As I've learned (from the comments from avherald.com), trimming is not a little bit nose up or down.
In the worst case, trimming cannot be compensated by the pilot's input, because the range of the trim system is greater(!!) than the range of the stick.
If the AOS sensor is faulty, the STAB TRIM CUTOUT switches must be set to CUTOUT by the pilot.
I do not understand why Boeing does not turn off the trim system by software when the AOS sensor generates bad data.
-
IIRC, the issue was the flight crew's uncertainty that they could access all the fuel onboard during one-engine-INOP operations, not that they didn't have enough overall fuel onboard.
IOW, they were concerned about fuel starvation, not fuel exhaustion.
-
IIRC, the issue was the flight crew's uncertainty that they could access all the fuel onboard during one-engine-INOP operations, not that they didn't have enough overall fuel onboard.
IOW, they were concerned about fuel starvation, not fuel exhaustion.
Then the FAA tried to fine them for not being airworthy. A UK aircraft in international or UK airspace when the fuel emergency was called. The UK CAA (their equivalent of the FAA) disagreed and said the plane was certified airworthy with only 3 engines. I gather the FAA accepted that in the end.
-
They did. The FAA concern was over the engine out in California, not the later emergency in Manchester. But the FAA backed down as the aircraft was certified to operate on 3. (Uncomplicated loss of engine in a 747 is an "abnormal" procedure, not an "emergency" procedure.)
-
Large airliners undergo substantial changes in elevator trim, particularly when landing flaps are deployed. It is often marginal as to whether the pilots could exert enough force on the controls to maintain attitude without the help of the trim tabs. Conversely if a trim tab goes to an extreme position and cannot be reset, this can be a mission critical situation.
Interestingly, in the event of elevator drive failure it is often possible for a skilled pilot to make a safe landing by flying the plane with the trim control.
-
However, the Boeing 737 is NOT a fly-by-wire aircraft.
It's not a 100% fly by wire AC but it does have fly-by-wire control of spoilers.
Brian
-
However, the Boeing 737 is NOT a fly-by-wire aircraft.
It's not a 100% fly by wire AC but it does have fly-by-wire control of spoilers.
Brian
I learned something new. You're right, but ONLY for the ~200 737-MAX's that have been delivered. Most of the thousands of 737's out there are 0% fly-by-wire. So for the MAX, let's call it 5% to be generous? Spoiler use in normal flight is limited to descents and landings. Most of its advanced features have to be enabled by the pilots, and most features are locked out when the flaps are not extended, even if turned on.
http://www.b737.org.uk/max-spoilers.htm (http://www.b737.org.uk/max-spoilers.htm)
I'd be pretty surprised if the spoilers were a negative factor in this crash.
-
I have a Raspberry Pi + $12 USB Software Defined Radio in my garage
o you share? I use a proper Equipment for.
I wouldn't mind setting up a receiver, but i can't find a map of existing installations?
https://flightaware.com/adsb/coverage#feeder-sites
I just got the stuff to set up a receiver and came across this page that shows the existing feeder sites and coverage.
-
Lion Air was a daytime flight, with largely visual conditions prevailing. I'm going to fully withhold judgment until more information (including CVR transcripts) is available, but based on the information available, this seems a lot closer to "speedometer was covered up by a piece of paper fluttering around the cabin and operator couldn't keep the car between 40 and 80 mph without that reference" than the scenario you describe (which I'd argue was still salvageable by fully-qualified crew, on an average day, but not by that crew on that evening).
At this stage that's my guess too (with my obvious in-depth knowledge of aviation with one flight and 3hrs flying time under my belt ::) ).
No bad weather, daytime, maybe some clouds making horizon reference a bit tricky, but with no actual fault in the plane control systems, it should have been work-aroundable and completely flyable.
But of course one small thing can often send you down a path that doesn't end well.
They did report issues and were returning to the airport at the time of the incident, so should have been in super-alert troubleshooting mode fresh into the lfight, and not half way across the atlantic 8 hours in and tired and shit suddenly hits the fan.
Actually the weather was very hazy so, over the water, the horizon would have been very indistinct and maybe even invisible. And the aircraft was undergoing radical pitch excursions resulting in wildly varying g-forces, and several different audible alarms were going off in the cockpit. Cabin crew, unsecured in seats, may have been injured or having to deal with passenger injuries due to the aircraft's attitude changes during the struggle to maintain control. This is why I described the "roo" situation as I did. In many ways this event was _worse_ than AF447, which was in a stable "mushing stall" all the way to the water and could have been flown out to normal flight had the pilots actually flown it out by simply lowering the nose and adding power. This aircraft was broken, and even if the pilots could have recovered it, it would still be broken and causing problems all the way until landed -- or crashed.
So yes -- pilot error, but in an environment where it was incredibly easy to make errors and be distracted, and at an altitude that did not allow time for evaluation -- or mistakes.
-
When the cabin crew is seated in their jumpseats, they are typically secured by shoulder straps. This plane was in trouble so soon after takeoff, I doubt the cabin crew was ever given clearance to move around, nor are they likely to do so on their own when things are clearly going wrong. Not that it mattered in the end, dead is dead.
-
However, the Boeing 737 is NOT a fly-by-wire aircraft.
It's not a 100% fly by wire AC but it does have fly-by-wire control of spoilers.
Brian
I learned something new. You're right, but ONLY for the ~200 737-MAX's that have been delivered. Most of the thousands of 737's out there are 0% fly-by-wire. So for the MAX, let's call it 5% to be generous? Spoiler use in normal flight is limited to descents and landings. Most of its advanced features have to be enabled by the pilots, and most features are locked out when the flaps are not extended, even if turned on.
http://www.b737.org.uk/max-spoilers.htm (http://www.b737.org.uk/max-spoilers.htm)
I'd be pretty surprised if the spoilers were a negative factor in this crash.
All aircraft have autopilot and this is true for more than 50 years -- these system permit the computer to control the aircraft even in AC that are not fly-by-wire. So, the fact remains that modern aircraft place a computer between the pilot and the control surfaces even when the plane is not fly-by-wire in the technical sense. In operation the computer fly's the plane most of the time including climb-out and descent. If the pilots are not well versed in the methods to arrest control from the computer they are in trouble -- and again, this also applies to non fly-by-wire AC though to a lessor extent.
It will be interesting to find out which system, the pilots or the computer, were responsible for the dive that doomed them!
Brian
-
But of course one small thing can often send you down a path that doesn't end well.
Just a nit here, but few aviation accidents are caused by one thing going wrong. There is usually a rather long accident chain. In this case, we already know that there is a) potentially a design error b) definitely a flight manual documentation error (this is what the AD that Boeing put out modifies) c) a known sensor issue that was sent for repair d) a plane that was not test-flown after a sensor repair and then e,f,... whatever happened in the cockpit that we do not know about yet, but I'm willing to bet that more than one mistake was made.
I'm not an airline pilot, but I am an instrument-rated private pilot with about 500 hours and I'm also a voracious consumer of accident reports.
-
Just for reference, this is the actual emergency Airworthiness Directive that Boeing has sent out:
https://c-3sux78kvnkay76x24znkgox78iax78x78ktzx2eius.g00.flyingmag.com/g00/3_c-3ccc.lreotmsgm.ius_/c-3SUXKVNKAY76x24nzzvyx3ax2fx2fznkgox78iax78x78ktz.iusx2fcv-iutzktzx2favrugjyx2f8674x2f77x2fH393-SGD-GJ-7763.vjl_$/$/$/$/$/$?i10c.ua=1&i10c.dv=14 (https://c-3sux78kvnkay76x24znkgox78iax78x78ktzx2eius.g00.flyingmag.com/g00/3_c-3ccc.lreotmsgm.ius_/c-3SUXKVNKAY76x24nzzvyx3ax2fx2fznkgox78iax78x78ktz.iusx2fcv-iutzktzx2favrugjyx2f8674x2f77x2fH393-SGD-GJ-7763.vjl_$/$/$/$/$/$?i10c.ua=1&i10c.dv=14)
It is, in its entirety, an update to the flight manual.
I see three basic elements to it:
1. x, y, and z are signs of a AOA sensor failure, with certain confusing instrument indications, including a potentially erroneous and changing minimum speed bar on the ASI
2. pilots should respond to such failures by disconnecting the auto stabilizer trim system
3. pilots should expect to need to use extra control force to overcome the auto stab system until it has been disconnected
Based on this, it would seem that Boeing suspects that the airplane was flyable, but that the crew did not react as they should, perhaps due to poor training or lack of awareness of this particular failure mode. Of course, that's what Boeing would say. OTOH, crashes are really bad PR and they'd ground the planes if they suspected there was areal system problem.
-
Just for reference, this is the actual emergency Airworthiness Directive that Boeing has sent out:
https://c-3sux78kvnkay76x24znkgox78iax78x78ktzx2eius.g00.flyingmag.com/g00/3_c-3ccc.lreotmsgm.ius_/c-3SUXKVNKAY76x24nzzvyx3ax2fx2fznkgox78iax78x78ktz.iusx2fcv-iutzktzx2favrugjyx2f8674x2f77x2fH393-SGD-GJ-7763.vjl_$/$/$/$/$/$?i10c.ua=1&i10c.dv=14 (https://c-3sux78kvnkay76x24znkgox78iax78x78ktzx2eius.g00.flyingmag.com/g00/3_c-3ccc.lreotmsgm.ius_/c-3SUXKVNKAY76x24nzzvyx3ax2fx2fznkgox78iax78x78ktz.iusx2fcv-iutzktzx2favrugjyx2f8674x2f77x2fH393-SGD-GJ-7763.vjl_$/$/$/$/$/$?i10c.ua=1&i10c.dv=14)
It is, in its entirety, an update to the flight manual.
I see three basic elements to it:
1. x, y, and z are signs of a AOA sensor failure, with certain confusing instrument indications, including a potentially erroneous and changing minimum speed bar on the ASI
2. pilots should respond to such failures by disconnecting the auto stabilizer trim system
3. pilots should expect to need to use extra control force to overcome the auto stab system until it has been disconnected
Based on this, it would seem that Boeing suspects that the airplane was flyable, but that the crew did not react as they should, perhaps due to poor training or lack of awareness of this particular failure mode. Of course, that's what Boeing would say. OTOH, crashes are really bad PR and they'd ground the planes if they suspected there was areal system problem.
Boeing seems to have acted quickly and responsibly here though time will tell. And, as I pointed out before and in spite of the fact that this plane is not technically fly-by-wire, the computer interposes itself between the pilot and control surfaces in a myriad of ways so taking 100% manual control is rather more complicated than pressing a single button.
Best guess is that the pilots were too 'heads down' trying to make sense of things and didn't notice the plane was in descent until it was too late. Again, there is going to be blame enough for everyone and the lawyers will profit...
Brian
-
And, as I pointed out before and in spite of the fact that this plane is not technically fly-by-wire, the computer interposes itself between the pilot and control surfaces in a myriad of ways so taking 100% manual control is rather more complicated than pressing a single button.
You have said this, and I'm pretty sure it's not correct in any operational sense in any Boeing airliner. Disconnecting the AP is indeed a single button push -- and that button is on the yoke, too, right where it can be pressed in an instant. The plane can also adjust the trim automatically, and as the AD makes clear, that can also be turned off. But even if not turned off, it can be overridden by the pilot's controls without any special action other than pushing or pulling harder than usual. Similarly, there's an trim and automatic yaw damper on the rudder which the pilot can disengage, but he can also kick the rudder however he wants and the machine will obey.
Boeing has aircraft such as the 777 that have FBW, but their philosophy is quite a bit different than Airbus's. The machine will essentially inform the pilot that he is about to exceed the aircraft's envelope by making it increasingly difficult for him to assert his control input (by pushing back against his inputs), but it will not override him. Check out section 11.3 of this document: http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_11.pdf (http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_11.pdf)
So, though there are systems (electric, hydraulic) between the pilot an the control surfaces, the pilots commands ARE obeyed unless something has actually broken.
This is totally different from an Airbus aircraft, where the computer under "normal law" enforces the flight envelope no matter the control inputs. There are several other modes the aircraft can be in, such as "alternate law 1" where the plane continues to enforce most of the envelope except AOA and overspeed, and "alternate law 2" where only load factor is enforced, and of course "direct law" which is basically "you're on your own kid."
In this case, it looks like the computer might have pushed the nose down, but the pilot could have counterracted that with the normal controls, albeit, with extra force.
-
And, as I pointed out before and in spite of the fact that this plane is not technically fly-by-wire, the computer interposes itself between the pilot and control surfaces in a myriad of ways so taking 100% manual control is rather more complicated than pressing a single button.
You have said this, and I'm pretty sure it's not correct in any operational sense in any Boeing airliner. Disconnecting the AP is indeed a single button push -- and that button is on the yolk, too, right where it can be pressed in an instant. The plane can also adjust the trim automatically, and as the AD makes clear, that can also be turned off. But even if not turned off, it can be overridden by the pilots controls without any special action other than pushing or pulling harder than usual.
The problem with applying continued force to overcome the airplane's trim is that the auto-trim will continue to trim against you (essentially by design). Airplane is on autopilot and trying to fly a course consistently lower than the aircraft is heading? The airplane will add nose-down trim. If the pilot continues to pull against that, they can, but the airplane will sense that the autopilot is not following the programmed pitch and will continue to trim nose down. On every aircraft I've flown, which is mostly piston singles and twins, but includes a few jets, pressing and holding the AP Disconnect switch will kill power to the auto-trim system and pitch trim motors.
Minor nit: it's "yoke" not "yolk"
-
Minor nit: it's "yoke" not "yolk"
Hah, I promised myself I would never do that again. Oh well.
I think we're in agreement. Yes, the AP/trim will work against you more and more but at the same time, that feeling of working against trim is going to be very familiar to any pilot who has ever flown with an AP. Particularly when you're having a "what is Otto doing now" moment, I can't think of anything more natural than disconnecting the AP and putting the plane into the state I want, while I figure out why the AP has different plans.
Admittedly, this is coming from someone whose time is mostly in older light singles with reliably unreliable autopilots.
-
I suspect we agree on almost everything about this crash, at least based on what is known now.
One difference in larger aircraft than in the light singles that you have experience in is that many larger aircraft trim systems work by changing the angle of incidence of the horizontal stabilizer with respect to the fuselage. (It literally cranks the tail "nose up" or "nose down" usually with a jackscrew.) Systems like this have the capability to overpower the pilot's inputs to a much greater extent than the "flying trim tabs" on most light singles. (Among light singles, as far as I know the only common types to use this system are most Mooneys, Piper's TriPacer, and the Cessna 185.)
-
I don't know how long it will take for the formal report but I would expect an overview of the FDR and CVR within 4-6 weeks. It may not answer all questions, but it should provide more details on the technical problems and, hopefully, address the factual situation with respect to which system, pilots or computer, produced the nose down attitude that resulted in the crash. We can quibble over just how much automation this AC had but the fact remains this wasn't a purely manual AC and the pilots would need to do certain things to take the computer out of the loop.
The facts about that particular truth should be clear as day in the FDR and the CDR should help elucidate the pilots actions during the 13 minutes of the flight.
Brian
-
Boeing screwed up putting an extra (undocumented) "Maneuvering Characteristics Augmentation System" to compensate for "some unique aircraft handling characteristics."
It relies on the AOA sensor and automatically lowers the plane's nose into a dive if it figures a stall condition exists.
No way for pilots to know about it- Boeing has nothing mentioned in training, difference, manuals etc.
APA to American's pilots "This is the first description you, as 737 pilots, have seen" :palm:
https://www.chicagotribune.com/business/ct-biz-boeing-indonesia-737-crash-20181113-story,amp.html (https://www.chicagotribune.com/business/ct-biz-boeing-indonesia-737-crash-20181113-story,amp.html)
-
Boeing screwed up putting an extra (undocumented) "Maneuvering Characteristics Augmentation System" to compensate for "some unique aircraft handling characteristics."
It relies on the AOA sensor and automatically lowers the plane's nose into a dive if it figures a stall condition exists.
No way for pilots to know about it- Boeing has nothing mentioned in training, difference, manuals etc.
APA to American's pilots "This is the first description you, as 737 pilots, have seen" :palm:
https://www.chicagotribune.com/business/ct-biz-boeing-indonesia-737-crash-20181113-story,amp.html (https://www.chicagotribune.com/business/ct-biz-boeing-indonesia-737-crash-20181113-story,amp.html)
How can it determine that ?
Airspeed ?
Are we back to suspecting blocked pitot tubes for this to happen ?
-
I'm not sure who makes the 737 max sensor pitot or AOA sensor, it's kind of hush. Thales or UTC etc.
My understanding is the AOA sensor measures pressure at the wing leading edge and together with the pitot you get differential (wing) pressure indicating lift. Some sensors combine both (mechanically) with a second pressure port in the pitot sensor. AOA is not an absolute angle sensor.
If either pressure sensor is malfunctioning, software may act thinking there is a stall condition, there is no lift.
-
Yes thanks, some further understanding here:
http://www.dynonavionics.com/aoa-pitot-probes.php (http://www.dynonavionics.com/aoa-pitot-probes.php)
-
Well, we'll all guessing here, but I still would be very surprised if pilots were not mentally equipped for a "runaway" trim problem where the trim/AP does something unexpected. Even if the cause of this runaway is novel, the idea that it can happen, and what you would do in that case would hardly be.
Yes, I'm pulling this from my rear, but at the same time, it's such a basic airmanship thing: you are flying an airplane that has (not so) little motors that can adjust control surface trims and those motors are connected to a sophisticated box that, though pretty great, is fallible. You need to be ready to disconnect those motors in a hurry, and the "why is the control system doing this" question can be handled later.
Which is not to say that there isn't be a problem with the aircraft design -- it sounds like there very well may be. I just think that some of the fault is going to remain on the pilots.
Accidents can have more than one contributing cause.
by the way, here's a relevant page from a 737 QRH (not a -MAX, I'm sure) (http://jira.icesoft.org/secure/attachment/21680/qrh%20rev36%20-800%2027k.pdf (http://jira.icesoft.org/secure/attachment/21680/qrh%20rev36%20-800%2027k.pdf)) for runaway stab trim
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=571235)
It does not get more straightforward than that.
-
Yes, I'm pulling this from my rear, but at the same time, it's such a basic airmanship thing: you are flying an airplane that has (not so) little motors that can adjust control surface trims and those motors are connected to a sophisticated box that, though pretty great, is fallible. You need to be ready to disconnect those motors in a hurry, and the "why is the control system doing this" question can be handled later.
Which is not to say that there isn't be a problem with the aircraft design -- it sounds like there very well may be. I just think that some of the fault is going to remain on the pilots.
Accidents can have more than one contributing cause.
Given that the emergency AD is a slightly wordier version of "in case of runaway trim, follow the existing runaway trim procedure", it's a pretty safe bet that a lot of the blame is going to land on the dead guys up front.
No specific differences training, blah, blah, blah, don't care. You're right; it is a basic airmanship thing and there are several ways to kill the trim, 3 of which I believe are memory items.
The trim wheels are also not small (intentionally so) and make a clicking racket when in motion (also intentional):
https://www.youtube.com/watch?v=cQirIH_DuAs (https://www.youtube.com/watch?v=cQirIH_DuAs)
-
Pilots says Boeing didn't disclose 737's new control feature
https://komonews.com/news/nation-world/were-p-sed-pilots-says-boeing-didnt-disclose-737s-new-control-feature
-
Pilots says Boeing didn't disclose 737's new control feature
https://komonews.com/news/nation-world/were-p-sed-pilots-says-boeing-didnt-disclose-737s-new-control-feature
Hmm, now that's interesting.
"But if that nose-down command is triggered by faulty sensor readings — as suspected in the Lion Air crash — pilots can struggle to control the plane, which can go into a dive and perhaps crash, according to a Boeing safety bulletin and safety regulators."
This sounds fishy. Faulty sensor readings, as those sensors are redundant, should be caught (if they aren't caught, then it's a very serious design problem).
Any decent flight helper such as this anti-stall mechanism SHOULD be automatically disconnected (of course with a clear warning) in case of faulty sensor readings. This would be way too dangerous otherwise. Interested in knowing more about all this...
-
So how fast can that trim throw the plane into a completely vertical dive?
-
"But if that nose-down command is triggered by faulty sensor readings — as suspected in the Lion Air crash — pilots can struggle to control the plane, which can go into a dive and perhaps crash, according to a Boeing safety bulletin and safety regulators."
This sounds fishy. Faulty sensor readings, as those sensors are redundant, should be caught (if they aren't caught, then it's a very serious design problem).
Suppose you have two independent pitot systems and they don't agree; which one is faulty? Suppose you have N independent pitot systems and they all agree but are all wrong (because of a common-mode maintenance failure, most likely); how do you automatically catch the fault?
Any decent flight helper such as this anti-stall mechanism SHOULD be automatically disconnected (of course with a clear warning) in case of faulty sensor readings. This would be way too dangerous otherwise. Interested in knowing more about all this...
IMO, we haven't established that the airplane can automatically "know" that a sensor reading is faulty. That's part (to a lot) of what the crew is there for. Unfortunately for this flight, that crew doesn't seem to have been up to the challenge of the hand they were dealt on that day.
-
Suppose you have two independent pitot systems and they don't agree; which one is faulty? Suppose you have N independent pitot systems and they all agree but are all wrong (because of a common-mode maintenance failure, most likely); how do you automatically catch the fault?
This. Furthermore, strange or divergent readings do not necessarily mean that any sensor is malfunctioning. You can have sensors on each wing and one wing might be stalled while the other is still flying. You can fly through a wind shear event that only effects one side of the airplane, or through another aircraft's wake turbulence, or get too slow while turning, or a combination of those factors -- all of which are the kinds of scenarios that have led to accidents and that one would imagine such a system is designed to detect.
It's a tricky business.
-
"But if that nose-down command is triggered by faulty sensor readings — as suspected in the Lion Air crash — pilots can struggle to control the plane, which can go into a dive and perhaps crash, according to a Boeing safety bulletin and safety regulators."
This sounds fishy. Faulty sensor readings, as those sensors are redundant, should be caught (if they aren't caught, then it's a very serious design problem).
Suppose you have two independent pitot systems and they don't agree; which one is faulty? Suppose you have N independent pitot systems and they all agree but are all wrong (because of a common-mode maintenance failure, most likely); how do you automatically catch the fault?
If there is disagreement, it obviously doesn't matter which one is wrong to detect there is a malfunction. This case would warrant the disconnection of any automatic system that could rely on or even be influenced by those sensors, and issue a warning. First thing that happens is usually the disconnection of the autopilot, and I'm pretty sure that happens when there is a faulty pitot, at least on Airbus planes. This is the first thing that happened on the AF447 for instance, AFAIK. Of course, this could be different in this case. Maybe.
Any redundant sensor system that would give the same figures but all wrong, and that those wrong figures could still pass as valid would be severely badly designed IMO, or this would be a case of extreme bad luck. Usually the different sensors should be located at different spots, ideally from different vendors, etc, so this should be rather unlikely. If it still happened, it can usually be figured out by the calculators since they would likely give figures that make no sense physically. The case were the measurements would all still seem valid to the calculators is not impossible but not very likely.
This is the whole point of redundant systems.
Any decent flight helper such as this anti-stall mechanism SHOULD be automatically disconnected (of course with a clear warning) in case of faulty sensor readings. This would be way too dangerous otherwise. Interested in knowing more about all this...
IMO, we haven't established that the airplane can automatically "know" that a sensor reading is faulty.
See above. If it can't, then there's a serious design flaw, or extreme bad luck IMO. When it comes to faulty sensors, the most common case is the crew either not able to fly the plane without the corresponding readings, or normally able but troubled under high stress and starting to not trust ANY of the plane readings and warnings, leading to sometimes deadly maneuvers.
We'll see.
-
If there is disagreement, it obviously doesn't matter which one is wrong to detect there is a malfunction. This case would warrant the disconnection of any automatic system that could rely on or even be influenced by those sensors, and issue a warning. First thing that happens is usually the disconnection of the autopilot, and I'm pretty sure that happens when there is a faulty pitot, at least on Airbus planes. This is the first thing that happened on the AF447 for instance, AFAIK. Of course, this could be different in this case. Maybe.
In the AF447 scenario, the computer decided it did not have reliable air data, so it not only disconnected the autopilot, it dropped into alternate law. Basically, the computer just punted and said "your airplane!" This might seem like reasonable behavior, but one might imagine that handing a degraded airplane to a pilot at the very worst moment is not a satisfactory failure mode, and in the AF447 scenario the outcome was obviously bad.
What else could the computer have been programmed to do? It could have perhaps dropped into an attitude-based straight-and-level flight mode, and made an annunciation inviting the pilots to take over, but not insisting that they do so that very instant.
But it's easy to second-guess these sorts of systems. It's not nearly as easy to design them so that they always do the thing that seems smartest in retrospect.
Any redundant sensor system that would give the same figures but all wrong, and that those wrong figures could still pass as valid would be severely badly designed IMO, or this would be a case of extreme bad luck.
I think you are underestimating the difficulty of this problem, because unusual attitudes and airspeeds are going to generate odd readings, and these are the exact situations -- not totally predictable -- where an AOA system is interesting.
Yes, one solution would be to have an array of AOA sensors from different vendors using different technologies, but you have to draw the line somewhere and you still need to integrate the data, and you still have to deal with the possibility that sensor #n, giving a strange reading is giving a correct strange reading. Maybe one sensor is at the wing root and another is at the tip, and the root is stalled and the tip is not. Or one wing is stalled and the other is not. Or both roots and one tip, but not the other, etc. Maybe the wing is physically damaged in some way that affects airflow and the sensor is correctly reporting that. All of those are aerodynamic situations that can happen.
Usually the different sensors should be located at different spots, ideally from different vendors, etc, so this should be rather unlikely.
But if they are in different spots, they're measuring different things. And "unlikely" is the exact problem. These aircraft are going to be flown 10's of thousands of hours and most of them are never going to ever get near a stall condition in their entire operational lives. Everything interesting an AOA system does is in well into the regime of "unlikely."
-
"But if that nose-down command is triggered by faulty sensor readings — as suspected in the Lion Air crash — pilots can struggle to control the plane, which can go into a dive and perhaps crash, according to a Boeing safety bulletin and safety regulators."
This sounds fishy. Faulty sensor readings, as those sensors are redundant, should be caught (if they aren't caught, then it's a very serious design problem).
Suppose you have two independent pitot systems and they don't agree; which one is faulty? Suppose you have N independent pitot systems and they all agree but are all wrong (because of a common-mode maintenance failure, most likely); how do you automatically catch the fault?
If there is disagreement, it obviously doesn't matter which one is wrong to detect there is a malfunction. This case would warrant the disconnection of any automatic system that could rely on or even be influenced by those sensors, and issue a warning. First thing that happens is usually the disconnection of the autopilot, and I'm pretty sure that happens when there is a faulty pitot, at least on Airbus planes. This is the first thing that happened on the AF447 for instance, AFAIK. Of course, this could be different in this case. Maybe.
Any redundant sensor system that would give the same figures but all wrong, and that those wrong figures could still pass as valid would be severely badly designed IMO, or this would be a case of extreme bad luck. Usually the different sensors should be located at different spots, ideally from different vendors, etc, so this should be rather unlikely. If it still happened, it can usually be figured out by the calculators since they would likely give figures that make no sense physically. The case were the measurements would all still seem valid to the calculators is not impossible but not very likely.
This is the whole point of redundant systems.
It turns out the airplane has to house and lift all these redundant systems into the air and carry them around the world. There's a real cost (in $$ and in safety) to excess weight in an airplane and a genuine engineering challenge to make the planes as safe as feasible, but when you add weight to an airplane, all else being equal, almost nothing good happens to safety. Runway performance is degraded, climb performance is degraded, range/fuel efficiency is degraded, stress on the tires and brakes is increased (longer, heavier, faster takeoff roll, more energy to dissipate in an RTO, etc), all of which have negative safety implications. (About the only thing that gets better is one specific input into the calculation of turbulent air penetration speed.)
When you start taking multiple different sensors of different types or from different vendors, now you have more complexity overall and wider tolerances to determine whether these two sensors agree or not. If you start adding a third or more to help break the tie, you have even more. At some point, you paid more in reduced safety than the safety you bought with the more redundant design. (Very quickly you paid more in $$, of course.)
I suspect that you're quite good in whatever your specific field is. I also suspect that there's something counterintuitive about your field where something is done a certain way, for good reason, but that reason isn't obvious to an outsider. When that situation has a light shone on it, outsiders might assume that they know more and that the practitioners in the field are obviously wrong, or they can wonder why something is done that way and start from an assumption that the skilled practitioners have a reason for it.
cf. Chesterton's Fence (https://www.chesterton.org/taking-a-fence-down/)
-
I don't know how long it will take for the formal report but I would expect an overview of the FDR and CVR within 4-6 weeks.
Did they find the CVR? I haven't been keeping up to date.
-
Not yet. (and the batteries on the locator beacon have now run out)
They found the AF447 black boxes though, long after they stopped pinging, so I'd expect there's a better than even chance that Lion Air's will be recovered eventually. It's mostly a question of how much money they are able to spend looking. I suspect it's properly "a lot".
-
The black box batteries are designed to operate the pinger for 30 days, and the crash was only 16 days ago. While it's correct to say we aren't hearing pings anymore, assuming the battery is the root cause of that is probably not correct.
-
Fair point taken.
-
I'm not sure who makes the 737 max sensor pitot or AOA sensor, it's kind of hush. Thales or UTC etc.
My understanding is the AOA sensor measures pressure at the wing leading edge and together with the pitot you get differential (wing) pressure indicating lift. Some sensors combine both (mechanically) with a second pressure port in the pitot sensor. AOA is not an absolute angle sensor.
If either pressure sensor is malfunctioning, software may act thinking there is a stall condition, there is no lift.
AOA sensors typically have a vane that turns as the relative wind angle changes. The vane will tend to rotate to the trailing edge of the wind-stream and as it does it reports that angle. Think of it as kind of like a small windmill that has a vane to keep the prop pointed into the wind.
As I mentioned before even AC that are not full on fly-by-wire AC have systems controlled by the computer that interpose themselves between the flight control surfaces and the pilot and if the story now being painted about an automated system installed by Boeing is correct then it makes it out to be perhaps more of a concern than a full fly-by-wire AC as the pilots may not be fully aware of the computer being in control.
Not looking good for Boeing if true...
Brian
-
I don't know anything about plane nor piloting one, its just watching this commentary from a former Inspector General US Dept of Transportation makes me worry me as an avg Joe.
-> https://edition.cnn.com/videos/tv/2018/11/14/ns-nov-14-intvw-boeing-witholds-info-mary-schiavo.cnn
-
I don't know how long it will take for the formal report but I would expect an overview of the FDR and CVR within 4-6 weeks.
Did they find the CVR? I haven't been keeping up to date.
I haven't heard, but given the relatively shallow water and proximity near shore it is just a matter of time before they do find it. I think the CVR may wind up being just as important as the FDR given the fact that the pilots have to do certain things to arrest control and at relatively low altitude if the computer commands a fairly steep dive they may only have a few seconds before its too late.
Hard to believe that 4.5 years later and we still haven't found MH370 -- if the Lion Air crash is something of a mystery the loss of MH370 is the mystery of the century.
Brian
-
I don't know anything about plane nor piloting one, its just watching this commentary from a former Inspector General US Dept of Transportation makes me worry me as an avg Joe.
-> https://edition.cnn.com/videos/tv/2018/11/14/ns-nov-14-intvw-boeing-witholds-info-mary-schiavo.cnn
IMO, as a pilot (albeit one with under 20 hours of jet time, though around 1500 hours in high performance singles and twins, and having attended type and recurrent trainings in simulators a handful of times), this is being overblown by the breathless media anxious for a story.
Yes, it seems like Boeing downplayed the differences in this airplane vs others on the same type certificate. Do I think that it rises to level of "not looking good for Boeing"? Sure. Do I think it rises to the level of "not being good for Boeing"? No, at least not yet. There's a lot of pressure to keep new airplanes on the same TC as existing designs. It seems very much expected that Boeing would pursue that course of action, including making design decisions with the constraint of "let's keep this airplane an A16WE".
From what I've read and viewed, I don't think that Boeing "withheld information" so much as "didn't highlight this particular system" and the same checklists and emergency procedures still applied as were applicable to the prior jets.
-
Making the new airplane fuel efficient at the expense of handling, then quietly adding an undocumented MCAS system to make up for it to supposedly keep the plane backwards-compatible with previous generations of 737's... Right now, Boeing's mistake is rightly causing a shitstorm.
https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610 (https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610)
But the root cause of the airspeed or AOA malfunction is still unknown. Even after Lion Air maintenance worked three times to fix the problem.
The plane's previous pilot encountered the same unintentional dive and then switched off the trim system, even though "it's not in the manual".
-
Making the new airplane fuel efficient at the expense of handling, then quietly adding an undocumented MCAS system to make up for it to supposedly keep the plane backwards-compatible with previous generations of 737's... Right now, Boeing's mistake is rightly causing a shitstorm.
https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610 (https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610)
But the root cause of the airspeed or AOA malfunction is still unknown. Even after Lion Air maintenance worked three times to fix the problem.
The plane's previous pilot encountered the same unintentional dive and then switched off the trim system, even though "it's not in the manual".
It is in the manual.
Previously posted by djacobow in this post:
https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1963691/#msg1963691 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1963691/#msg1963691)
-
Making the new airplane fuel efficient at the expense of handling, then quietly adding an undocumented MCAS system to make up for it to supposedly keep the plane backwards-compatible with previous generations of 737's... Right now, Boeing's mistake is rightly causing a shitstorm.
https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610 (https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610)
But the root cause of the airspeed or AOA malfunction is still unknown. Even after Lion Air maintenance worked three times to fix the problem.
The plane's previous pilot encountered the same unintentional dive and then switched off the trim system, even though "it's not in the manual".
It is in the manual.
Previously posted by djacobow in this post:
https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1963691/#msg1963691 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1963691/#msg1963691)
They omitted the total nightmare portion:
"The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released.
Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC."
The bulletin was just issued by Boeing Nov. 6
-
Making the new airplane fuel efficient at the expense of handling, then quietly adding an undocumented MCAS system to make up for it to supposedly keep the plane backwards-compatible with previous generations of 737's... Right now, Boeing's mistake is rightly causing a shitstorm.
https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610 (https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610)
But the root cause of the airspeed or AOA malfunction is still unknown. Even after Lion Air maintenance worked three times to fix the problem.
The plane's previous pilot encountered the same unintentional dive and then switched off the trim system, even though "it's not in the manual".
It is in the manual.
Previously posted by djacobow in this post:
https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1963691/#msg1963691 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1963691/#msg1963691)
They omitted the total nightmare portion:
"The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released.
Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC."
The bulletin was just issued by Boeing Nov. 6
Yes, that's what can happen if you don't put the trim in cutout. If you follow the QRH and don't re-engage the trim, you're fine.
-
The bulletin was just issued by Boeing Nov. 6
That bulletin contains the following quote: (emphasis Boeing's)
Subject: Uncommanded Nose Down Stabilizer Trim Due to Erroneous Angle of Attack (AOA) During Manual Flight Only
Reason: To Emphasize the Procedures Provided in the Runaway Stabilizer Non Normal Checklist (NNC).
In other words, "follow the existing procedures as previously published".
-
... systems controlled by the computer that interpose themselves between the flight control surfaces and the pilot ...
You keep saying BETWEEN, trying to impose the definition of fly-by-wire on systems that aren't. The reality is ALONGSIDE; manual controls still work, and in most cases can overpower the automatics even if they are not switched off. The pilots are NOT disconnected from the control surfaces. Even with all the updates over decades, the 737 remains a very successful 1960's era design at the core.
The data recorder is going to have all we need to know about automatic vs manual inputs to the system, as well as what the instruments were saying at the time. It should also shoot down 95% of the speculation in this thread, once a decent analysis is released. But we really need that cockpit recorder to know what was going on in the heads of the pilots for those last 10 minutes.
However they got there, I'm guessing they ended up in an actual aerodynamic stall. Which, even when in full control, is likely not recoverable in the <5000 feet they had available. It fits the information we have so far. (For the benefit of the non-pilots, the way to regain control from a full stall is to enter a dive to regain airspeed, and then you have to recover from the dive. You lose a LOT of altitude in the process, very quickly.)
-
It's too easy to blame the pilots for "not flipping the off switch" in the stabilizer trim circus. Assuming that is the fatal error here.
The finest engineering and latest technology, and the system to prevent pilot error (stall) malfunctions with bad sensor data and ends up causing pilot error. An automatic control system fighting the pilot to his death.
Cryptic annunciators from the 1960's are still in the cockpit and yet the LCD displays are just mimicking old analog gauges and cannot offer any assistance to help a panicked crew. A lot of people have died due to these aircraft sensor malfunctions causing control system and pilot errors. I would come up with something to stop this shit instead of attributing it to human error and repeating the tragedies.
-
However they got there, I'm guessing they ended up in an actual aerodynamic stall. Which, even when in full control, is likely not recoverable in the <5000 feet they had available. It fits the information we have so far. (For the benefit of the non-pilots, the way to regain control from a full stall is to enter a dive to regain airspeed, and then you have to recover from the dive. You lose a LOT of altitude in the process, very quickly.)
I don't think that theory fits the flightradar24 data (https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/), nor does it fit the data of Boeing/FAA releasing an emergency AD about preventing stab trim runaway in the face of the stability augmentation system malfunction due to possibly erroneous AoA inputs. Neither of those is ironclad of course, but the high sink rate began to develop at a ground speed well in excess of the typical unaccelerated stall speed even fully clean.
It looks like the sink rate begins to develop with the ground speed in excess of 310 knots and the ground speed increases as the sink rate increases. That seems more consistent with a[n aerodynamically] controlled flight scenario rather than a departure [from controlled flight].
-
It's too easy to blame the pilots for "not flipping the off switch" in the stabilizer trim circus. Assuming that is the fatal error here.
Is it too much to ask a trained flight crew to follow checklists? IMO, it's not.
-
It's too easy to blame the pilots for "not flipping the off switch" in the stabilizer trim circus. Assuming that is the fatal error here.
Is it too much to ask a trained flight crew to follow checklists? IMO, it's not.
3 out of 4 flight crews seemed to handle this airplane's issues. Human error is well known to exist. Especially with a mystery control system that we also assume is flawless, containing no software errors from its human software engineers.
We don't know what happened in the cockpit that prevented the flight crew to follow a checklist. The alarms, stick shaking and sharp dive causing near zero G, wonky airspeed may have been part of it.
At some point it's like engineering has given up on humans, their reliability is poor and they are error-prone, so embedded systems are trying to take over.
Cars are heading full force towards self driving. I have already seen "driver assist" technology with automobiles malfunction.
The radar malfunctions in rain/snow and thinks you are going to hit an obstacle on a good puddle splash. Next gen is full brakes/steering/accelerator capability :o
-
... systems controlled by the computer that interpose themselves between the flight control surfaces and the pilot ...
You keep saying BETWEEN, trying to impose the definition of fly-by-wire on systems that aren't. The reality is ALONGSIDE; manual controls still work, and in most cases can overpower the automatics even if they are not switched off. The pilots are NOT disconnected from the control surfaces. Even with all the updates over decades, the 737 remains a very successful 1960's era design at the core.
The data recorder is going to have all we need to know about automatic vs manual inputs to the system, as well as what the instruments were saying at the time. It should also shoot down 95% of the speculation in this thread, once a decent analysis is released. But we really need that cockpit recorder to know what was going on in the heads of the pilots for those last 10 minutes.
However they got there, I'm guessing they ended up in an actual aerodynamic stall. Which, even when in full control, is likely not recoverable in the <5000 feet they had available. It fits the information we have so far. (For the benefit of the non-pilots, the way to regain control from a full stall is to enter a dive to regain airspeed, and then you have to recover from the dive. You lose a LOT of altitude in the process, very quickly.)
The pilot in a non-fly-by-wire AC is the controlling element and the control surfaces are the elements being controlled. When a pilot commends an action but the computer commands something else the pilot in command is not in command the way they may wish. The computer has its say and while you could play semantics and say its ALONGSIDE versus in between the consequence is the same is it not. The fact remains that even in a non-fly-by-wire AC the computer can take control and circumvent the intentions of the pilots.
I'm not sure what's driving your semantic dispute but as far as I'm concerned this is what it is. At low altitude if the computer puts the plane into a dive the pilots may not have enough time to turn off the system and recover. Let's say the plane is at 5000 feet at 400 knots and the computer issues a trim command that puts the plane into a 30 degree dive -- without intervention they would be less than 17 seconds before impact. They would have much less than that to react, turn off the system, and pull out of the 30 degree dive. In fact, if the plane got to a 30 degree dive at 5000 feet it may already be too late and there would be nothing to prevent disaster even if they turned off the system, correctly, the instant that happened.
Brian
-
The trim wheels are also not small (intentionally so) and make a clicking racket when in motion (also intentional):
https://www.youtube.com/watch?v=cQirIH_DuAs (https://www.youtube.com/watch?v=cQirIH_DuAs)
do NOT attempt to stop it by putting your palm over a running wheel as this leads to a burn
:o I'm not a pilot but trying to grab hold of a rapidly and forcefully spinning object sounds rather dangerous and reminds me of lathe safety lessons... there's no disconnect mechanism?
-
The first means to stop runaway trim is auto-pilot disconnect (generally the biggest red switch on the outside yoke arm, easily accessible by your thumb).
The second means is by turning the switch off to the system.
The third means is to grab the metal wheel and force against the clutch that's driving it.
It's not especially dangerous and certainly is less dangerous than allowing a runaway trim condition to continue!
-
I'm not sure what's driving your semantic dispute but as far as I'm concerned this is what it is. At low altitude if the computer puts the plane into a dive the pilots may not have enough time to turn off the system and recover. Let's say the plane is at 5000 feet at 400 knots and the computer issues a trim command that puts the plane into a 30 degree dive -- without intervention they would be less than 17 seconds before impact.
The dispute, I think, comes from you not quite getting how flying feels. If the plane is flying on AP and your attention is elsewhere, yes, the computer can put the plane into a dive. (Though honestly, 17 seconds is a long time to grab the control right in front of you and arrest that dive -- though not too fast, you don't want an accelerated stall.)
But if your hands are on the controls, the computer cannot "put the plane into a dive." What it can do is trim the plane to dive, which you will immediately (as in before the attitude actually changes) perceive as a very unpleasant sudden nose heaviness. Every pilot knows what an uncommanded trim change feels like while flying. It doesn't feel good, it's a lizard brain muscle memory, and I think the vast majority of pilots would fight it immediately while simultaneously reaching for the trim controls.
The exception to this would be if the pilot was also getting stall warnings; then he might hesitate before pulling back. But in clear weather I think it would only be a few seconds before, looking at the aircraft's attitude and power settings, he could surmise that the aircraft wasn't actually near a stall.
-
... systems controlled by the computer that interpose themselves between the flight control surfaces and the pilot ...
You keep saying BETWEEN, trying to impose the definition of fly-by-wire on systems that aren't. The reality is ALONGSIDE; manual controls still work, and in most cases can overpower the automatics even if they are not switched off. The pilots are NOT disconnected from the control surfaces. Even with all the updates over decades, the 737 remains a very successful 1960's era design at the core.
The data recorder is going to have all we need to know about automatic vs manual inputs to the system, as well as what the instruments were saying at the time. It should also shoot down 95% of the speculation in this thread, once a decent analysis is released. But we really need that cockpit recorder to know what was going on in the heads of the pilots for those last 10 minutes.
However they got there, I'm guessing they ended up in an actual aerodynamic stall. Which, even when in full control, is likely not recoverable in the <5000 feet they had available. It fits the information we have so far. (For the benefit of the non-pilots, the way to regain control from a full stall is to enter a dive to regain airspeed, and then you have to recover from the dive. You lose a LOT of altitude in the process, very quickly.)
You're right, I'm not familiar with fly-by-hose where you have two hydraulic systems battling it out.
It's still not making sense from many perspectives.
If a pilot makes an error causing a stall and the MCAS tries to correct it yet still allows the pilot to override that, I'm not sure what the point is. An adamant pilot can still go into and stay in a stall condition, as flight 447 did.
Why are you needing to switch off power to the stab trim system if you can overrule it.
The AOA sensor had been replaced, so the airspeed sensor or something else must have been aggravating all this.
The cockpit voice recorder beacon (https://www.l3aviationproducts.com/products/90-day-beacon) looks like its rated for 90-day battery life and 1.8-3.6km range. 160dB chirp at 37.5kHz but buried under mud or debris. It would have many answers.
-
If a pilot makes an error causing a stall and the MCAS tries to correct it yet still allows the pilot to override that, I'm not sure what the point is.
The point is that the system has "told" the pilot something. The pilot can integrate that information in his picture of what is going on. He can let the automation do what it wants, or, if he believes he knows something the computer doesn't, he can fight it. That's the Boeing philosophy. The Airbus philosophy is that the pilot will need to take extraordinary steps (in advance) to override the aircraft.
I really do not think there is enough accident data out there these days to make a good assessment of which approach is safer overall. It's a very complex question because very sophisticated automation tend to de-skill operators, which becomes an acute problem in the few cases where the automation fails.
(such as An adamant pilot can still go into and stay in a stall condition, as flight 447 did.
But the A320 is an FBW aircraft, and so normally, a pilot could not stall it. But in this case, the computer had punted and dropped into "alternate law" where the not all the normal envelope protections were applied.
Why are you needing to switch off power to the stab trim system if you can overrule it.
Because you will tire of overruling it continuously. It takes physical and mental effort to fly an untrimmed aircraft, much less one that keeps trying to make itself untrimmed.
-
Because it's not just semantics, especially when your primary argument is about what happens when computers misbehave.
In a fly-by-wire setup, if you lose all the flight control computers, you CANNOT fly the plane. The pilot controls are merely input devices to the computer, like a joystick, keyboard or mouse on a PC. No computer, no control. Turning them off is NOT an option if you want to live.
In the 737, while a lot of electronics are important, none of it is absolutely essential for flight. You can turn them all off and still have operating controls to fly the plane with.
-
I'm not sure what's driving your semantic dispute but as far as I'm concerned this is what it is. At low altitude if the computer puts the plane into a dive the pilots may not have enough time to turn off the system and recover. Let's say the plane is at 5000 feet at 400 knots and the computer issues a trim command that puts the plane into a 30 degree dive -- without intervention they would be less than 17 seconds before impact.
The dispute, I think, comes from you not quite getting how flying feels. If the plane is flying on AP and your attention is elsewhere, yes, the computer can put the plane into a dive. (Though honestly, 17 seconds is a long time to grab the control right in front of you and arrest that dive -- though not too fast, you don't want an accelerated stall.)
But if your hands are on the controls, the computer cannot "put the plane into a dive." What it can do is trim the plane to dive, which you will immediately (as in before the attitude actually changes) perceive as a very unpleasant sudden nose heaviness. Every pilot knows what an uncommanded trim change feels like while flying. It doesn't feel good, it's a lizard brain muscle memory, and I think the vast majority of pilots would fight it immediately while simultaneously reaching for the trim controls.
The exception to this would be if the pilot was also getting stall warnings; then he might hesitate before pulling back. But in clear weather I think it would only be a few seconds before, looking at the aircraft's attitude and power settings, he could surmise that the aircraft wasn't actually near a stall.
If the plane is in a 30 degree dive at 5000 feet you'd have less than 17 seconds if you did nothing. However, disabling the trim then pulling out of the dive and doing that with 5000 feet to play with means you have less time than 17 seconds. If you were heads down and didn't notice until the plane was 30 degrees down at 5000 feet its a good bet you would not be able to recover even if you acted with zero delay. You don't arrest a 30 degree dive at 400+ knots without losing a fair bit of altitude. Physics is a bitch!
Brian
-
However, even the heads-down pilots will notice the bunt from level pitch to 30 degrees nose down. That's a negative g maneuver! Or if they have hands on the yoke (the suspect system allegedly only operates when manually flying) they will notice the sudden trim change as they have to apply considerable back pressure to prevent or recover from the bunt.
Physics is hard, but the ground is harder. Or in this case the water surface.
-
In the AF447 scenario, the computer decided it did not have reliable air data, so it not only disconnected the autopilot, it dropped into alternate law. Basically, the computer just punted and said "your airplane!" This might seem like reasonable behavior, but one might imagine that handing a degraded airplane to a pilot at the very worst moment is not a satisfactory failure mode, and in the AF447 scenario the outcome was obviously bad.
This seems reasonable, and I still think it is. I don't think Airbus has changed this behavior after this tragedy (but don't hesitate to tell us if they did, as I may have missed the info), so a lot of people have probably considered it reasonable as well. The moment this happened, the plane was NOT in a critical situation whatsoever as far as I remember, so yes this was stressful and pilots got misled somehow, but they would have had ample time to handle this the right way. Turns out that the training on those airliners with a lot of automation don't always have enough simulation sessions for handling this kind of situations, and that's one of the things they improved after the accident: training sessions. The warning indicators are not always very clear either, and this surely could be improved, but at least in this case, they were certainly not lacking as there was a continuous stream of warnings including stall warnings IIRC. The main point as I remember is the pilots were not trusting ANY indication anymore, so obviously they lost all reference and situational awareness.
Again, if some automated system RELIES on some sensor data and this data is DETECTED as not reliable, the system should obviously be disconnected.
That said, if alternate systems that DONT need those sensor data can still be activated to make it safer, of course this could be a good idea to activate them. But keeping on a system that takes some of the controll OFF the hands of the pilots based on unreliable data is a recipe for disaster. That's all I'm saying here, and this is also what has been pointed out and suspected in this Lion Air case by some.
Very interested in reading the final report.
-
In the AF447 scenario, the computer decided it did not have reliable air data, so it not only disconnected the autopilot, it dropped into alternate law. Basically, the computer just punted and said "your airplane!"
This seems reasonable, and I still think it is. I don't think Airbus has changed this behavior after this tragedy (but don't hesitate to tell us if they did, as I may have missed the info), so a lot of people have probably considered it reasonable as well.
I'd say it was reasonable, but unfortunate. And yes, I think if you have a crew that was so deficient in basic airmanship, there's ultimately not much you can do to help folks who are going to do stupid things. Assuming all your instruments are wrong because some of your instruments are wrong is not just dumb in an Airbus, it is dumb in any airplane. You can go right back to your basic instrument training in piston single: you can get work out and bad air data from the remaining instruments. In turbulence, I'm sure it's scary and difficult, but if the pilots had simply flown an attitude and power setting, they would have been fine. I think there's not much doubt about that.
This is the final BAE report on AF447, translated in English: https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf (https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf)
(SiWizard, from your flag, I suspect this version will be more to your liking: https://www.bea.aero/docspa/2009/f-cp090601/pdf/f-cp090601.pdf (https://www.bea.aero/docspa/2009/f-cp090601/pdf/f-cp090601.pdf))
Section 5 lists the changes after the aircraft. Basically, other than improving the pitot heaters, I don't think any changes were made to the aircraft. Several training and flight manual changes were made, such as making sure pilots understand that they are not getting stall protection under alternate law.
Completely revamping the flight control software on an airliner that has been in production for a long time perhaps would be a bridge too far, and add additional risk. Furthermore, improving the pitot system so that you don't get a total loss of air data would certainly be a simpler option. I wonder how many times since AF447 an A320 has lost air data. Maybe none?
-
... systems controlled by the computer that interpose themselves between the flight control surfaces and the pilot ...
You keep saying BETWEEN, trying to impose the definition of fly-by-wire on systems that aren't. The reality is ALONGSIDE; manual controls still work, and in most cases can overpower the automatics even if they are not switched off. The pilots are NOT disconnected from the control surfaces. Even with all the updates over decades, the 737 remains a very successful 1960's era design at the core.
Multiple sources are saying the MCAS system cannot be overridden by the pilot, unless power is cut.
This seems counter to what many are saying about fly-by-hose/wire systems or Boeing's philosophy?
"Any pilot’s natural reaction when a plane’s nose begins to tilt down uncommanded is to pull back on the yoke and raise the nose. In normal flight mode, that would work, because pulling back on the yoke triggers breakout switches that stop any automatic tail movement tending to move the nose of the plane down.
But with the MCAS activated, said Fehrm, those breakout switches wouldn’t work. MCAS assumes the yoke is already aggressively pulled back and won’t allow further pullback to counter its action, which is to hold the nose down."
FAA evaluates a potential design flaw on Boeing’s 737 MAX after Lion Air crash (https://www.seattletimes.com/business/boeing-aerospace/faa-evaluates-a-potential-design-flaw-on-boeings-737-max-after-lion-air-crash/)
-
Multiple sources are saying the MCAS system cannot be overridden by the pilot, unless power is cut.
This seems counter to what many are saying about fly-by-hose/wire systems or Boeing's philosophy?
Yes, it does certainly seem so based on this reporting. I think that's why former avionics engineers and a bunch of pilots are alarmed, especially if the behavior of the airplane has changed but the AFM doesn't reflect that change. It's subtle, I think. If you follow the procedure in the AFM to disable the trim system, it sounds like you're OK, but if you are relying on expectations that you can just pull back (as you have on all previous 737s), you'll get different behavior. Just speculating, but I'd bet the flight manual probably never said "just pull back until you can get the trim sorted," but perhaps pilots do exactly that, since in normal flight that works. I have no jet time, but in the much simpler aircraft I've flown, it's just what I would do. If the AP was doing something unusual, I would simultaneously disable the AP and use the primary controls first and then adjust trim to relieve control forces second.
But with the MCAS activated, said Fehrm, those breakout switches wouldn’t work. MCAS assumes the yoke is already aggressively pulled back and won’t allow further pullback to counter its action, which is to hold the nose down."
I'm a bit surprised the computer assumes anything about the position of the yoke. I'd have hoped it would know the position of the yoke. So, if the AOA sensor is saying one thing, but the position of the yoke and trim are not consistent with a stall, it might "think twice" about assuming a stall and forcing the nose down. But that might be a bit too much fuzzy reasoning to expect from a system like that.
-
Multiple sources are saying the MCAS system cannot be overridden by the pilot, unless power is cut.
This seems counter to what many are saying about fly-by-hose/wire systems or Boeing's philosophy?
Yes, it does certainly seem so based on this reporting. I think that's why former avionics engineers and a bunch of pilots are alarmed, especially if the behavior of the airplane has changed but the AFM doesn't reflect that change. It's subtle, I think. If you follow the procedure in the AFM to disable the trim system, it sounds like you're OK, but if you are relying on expectations that you can just pull back (as you have on all previous 737s), you'll get different behavior. Just speculating, but I'd bet the flight manual probably never said "just pull back until you can get the trim sorted," but perhaps pilots do exactly that, since in normal flight that works. I have no jet time, but in the much simpler aircraft I've flown, it's just what I would do. If the AP was doing something unusual, I would simultaneously disable the AP and use the primary controls first and then adjust trim to relieve control forces second.
But with the MCAS activated, said Fehrm, those breakout switches wouldn’t work. MCAS assumes the yoke is already aggressively pulled back and won’t allow further pullback to counter its action, which is to hold the nose down."
I'm a bit surprised the computer assumes anything about the position of the yoke. I'd have hoped it would know the position of the yoke. So, if the AOA sensor is saying one thing, but the position of the yoke and trim are not consistent with a stall, it might "think twice" about assuming a stall and forcing the nose down. But that might be a bit too much fuzzy reasoning to expect from a system like that.
And, if the pilots went with the 'pull back the stick option' as there first attempt at the altitude and airspeed they were at they would not have had time for option two -- this software system will have to be removed until a better thought out system can be implemented. Boeing is going to eat this one and it will cost there insurer hundreds of millions I'd wager.
The law of unintended consequences sometimes makes fools of your best plans.
Brian
-
https://www.youtube.com/watch?v=zfQW0upkVus (https://www.youtube.com/watch?v=zfQW0upkVus)
-
https://www.youtube.com/watch?v=zfQW0upkVus (https://www.youtube.com/watch?v=zfQW0upkVus)
The way he explains it makes it seem even worse than I thought. Potentially single failure combined with lack of training.
-
https://www.youtube.com/watch?v=zfQW0upkVus (https://www.youtube.com/watch?v=zfQW0upkVus)
I don't think there's much in this video that is different from what has been discussed on this thread so far. For now, I'm sticking with my "prediction" that the pilots and Boeing will end up with some of the responsibility. There's nothing here to imply that the aircraft could not be flown. It's definitely not okay that Boeing put in a new flight control system and made no mention of it in the true-up training for the MAX. On the other hand, if that system started moving trim according to rules unknown to them, that would seem like the very definition of runaway trim to pilots who didn't know about MCAS, and if they followed the procedure for that, they would have been fine.
-
Lets say they used the thumb sticks to pull trim back and then took out the checklist because they assume they have corrected the problem for now and have some breathing room, so now they are distracted and then the system hits trim again after the time out. It's just such a fucking mess.
IMO they need a big red button to turn off autopilot, but really, actually, completely, not partially.
-
It's a two-crew airplane for a reason. Pilot Flying (PF) does the memory items and calls for the checklist. Pilot Not Flying (PNF) pulls out the Quick Reference Handbook (QRH) and reads the checklist items in challenge form. PF responds with the response. The whole time PF keeps flying the airplane and monitoring its performance, including attitude and airspeed.
You don't have two people going heads-down into the books. (It happens, most notably, tragically, and avoidable in something in Eastern 401, where 101 people died because a cockpit crew of three mismanaged a burned out landing gear position indicator bulb. Since then, CRM classes have taught the division of duties to avoid future "two researchers, zero pilots" situations.)
-
If there is disagreement, it obviously doesn't matter which one is wrong to detect there is a malfunction. This case would warrant the disconnection of any automatic system that could rely on or even be influenced by those sensors, and issue a warning. First thing that happens is usually the disconnection of the autopilot, and I'm pretty sure that happens when there is a faulty pitot, at least on Airbus planes. This is the first thing that happened on the AF447 for instance, AFAIK. Of course, this could be different in this case. Maybe.
In the AF447 scenario, the computer decided it did not have reliable air data, so it not only disconnected the autopilot, it dropped into alternate law. Basically, the computer just punted and said "your airplane!" This might seem like reasonable behavior, but one might imagine that handing a degraded airplane to a pilot at the very worst moment is not a satisfactory failure mode, and in the AF447 scenario the outcome was obviously bad.
ISTM that Airbus have made fairly clear and consistent design choices. The flight envelope protection will not allow the pilots to stall or overspeed the aircraft unless the sensors start playing up (in a detectable way) or the pilots deliberately disable this system (which takes a single action). Not everyone likes the choices but they are reasonable. I agree with you that it is difficult to make changes that are unambiguously better.
Judging by the AD, the accretion of changes to the 737 has produced a system that is:
A - Badly documented (supposedly a deliberate choice to save time and money during training).
B - Does not completely handover control when the sensors disagree (even warning the pilots that the sensors are playing up is an optional extra! [1]).
C - Requires two actions, both disabling the autopilot and cutting out the trimming system.
I think Boeing have been caught out by the compromises involve in updating a very old design[2], marketing pressures[3] and - possibly - by their own propaganda regarding how traditional the flight controls on a Boeing are. My predictions are that:
A - Training will now heavily cover the auto trim systems.
B - The sensor disagreement warning will not be optional in practice (everyone will buy it)
C - Boeing may have to change the MCAS system by adding a cut-out when the sensors disagree (should have done that from the start IMHO).
I'm surprised at what is hidden from pilots both in the manuals and by making the sensor warnings optional. If pilots get a stall warning without an explicit indication that the sensors disagree[4] they may well believe it. Particularly if they have already been surprised by changes in the aircraft's motion (driven by the automated system's intervention) and so lost their 'feel' for whether the aircraft might plausibly be close to stalling. A curious and sad inversion of the AF447 crash if so.
All of this is my ill-informed opinion. Both Airbii and Boeings are flown very safely by sensible airlines. The Lion Air crash may well be something completely different, etc.
[1] Maybe Boeing could consider in-appflight purchases in this case? "We've noticed that your subscription does not include information helpful to your continued survival. Would you like to upgrade? (T&C apply. Always make sure you have the permission of the credit card holder. Offer not valid if you're going to sue us.)"
[2] First flight in 1967, 51 years ago and 64 years after the Wright brothers. Dates from wonkypedia, maths from my sligtly tired brain.
[3] Honestly, I get infuriated by manufacturers making an oscilloscope's actual capabilities an optional (i.e. expensive) upgrade and now Boeing's marketing department gets in on the game? And then nobbles the flight manual/ conversion course to boot?
[4] Do any of the checklists (memory or written) call for comparing the instruments?
-
C - Requires two actions, both disabling the autopilot and cutting out the trimming system.
This is standard. My 3600-pound airplane has the same basic response for an AP or electric trim malfunction. My previous 2800-pound airplane didn't have electric trim installed, but if it did, it would have been the same.
[4] Do any of the checklists (memory or written) call for comparing the instruments?
This is the fundamental skill of all instrument-rated pilots and a primary focus of instrument flight instruction.
-
https://www.youtube.com/watch?v=zfQW0upkVus (https://www.youtube.com/watch?v=zfQW0upkVus)
I don't think there's much in this video that is different from what has been discussed on this thread so far. For now, I'm sticking with my "prediction" that the pilots and Boeing will end up with some of the responsibility. There's nothing here to imply that the aircraft could not be flown. It's definitely not okay that Boeing put in a new flight control system and made no mention of it in the true-up training for the MAX. On the other hand, if that system started moving trim according to rules unknown to them, that would seem like the very definition of runaway trim to pilots who didn't know about MCAS, and if they followed the procedure for that, they would have been fine.
Umm, no...
If this runaway trim happened at 5000 feet and they spent even a few seconds fighting the stick by the time they did turn things off the plane would be at 3000 feet and 30 degrees down -- you won't recover from that even with the trim system turned off.
The idea that pilots will automatically and with zero delay jump to a seldom used (or never used) emergency procedure is delusional -- that's not how humans respond. They will attempt to pull back on the stick and then, maybe, realize they need to turn the trim off but by then...
Brian
-
You have to manually crank the stabilizers back to center, after shutting off power to the motors.
Can you imagine how hard that is, it's two BLDC with screw-jack and you don't have much time.
-
If this runaway trim happened at 5000 feet and they spent even a few seconds fighting the stick by the time they did turn things off the plane would be at 300 feet and 30 degrees down -- you won't recover from that even with the trim system turned off.
The idea that pilots will automatically and with zero delay jump to a seldom used (or never used) emergency procedure is delusional -- that's not how humans respond. They will attempt to pull back on the stick and then, maybe, realize they need to turn the trim off but by then...
I think neither of us are airline pilots, so we'll just have to disagree about this and find out what's in the reports when they come out. My sense as a pilot (not an airline pilot) is that this is EXACTLY the kind of thing that is -- or should be -- on a pilot's mind, particularly when climbing out at low altitude. As I've said before, these trim changes, though fast, are not instantaneous. They can be felt. Furthermore, a sudden trim change doesn't result in an instantaneous attitude change. (The plane has a moment of inertia and it takes time for the nose to rotate down). And an instantaneous attitude change does not result in an instantaneous altitude change. Some of these delays work against you as you try to arrest a descent just as they work for you at the start of the descent, but I'm nearly certain that proficient, attentive pilots can recovery from a runaway trim situation that starts at 5000 feet.
Yes, if you get into a 6000 fpm minute descent then you are probably screwed, but you'd really have to let the plane get into a seriously unusual attitude to get that kind of descent.
It may seem as if a few armchair pilots are being perhaps a bit too harsh on the pilots in this scenario -- and I'm willing to concede that maybe we are. But you have to understand that pilots are always supposed to be thinking of what can go wrong in each phase of flight and what they'd do about it. It's the essence of piloting. Flying a working airplane is not particularly hard. Managing a "normal" flight takes up a surprisingly small fraction of overall flight training. Most flight training is about handling abnormal situations, and dealing with those is the crux of a pilot's job. Cross checking instruments (including checking them against the huge non-artificial horizon available in VMC) and avoid and recovering from unusual attitudes are definitely in this category.
-
You have to manually crank the stabilizers back to center, after shutting off power to the motors.
Can you imagine how hard that is, it's two BLDC with screw-jack and you don't have much time.
Pretty sure it is somewhere between 'very hard' and 'impossible' once the system has gone full nose heavy. In a manual operation, it is a LOT of turns and needs considerable effort to move. All of that has to be accomplished in the middle of a very confusing and scary emergency event that is very rapidly getting worse. There is little doubt that both pilots knew it was a deadly situation early on which would make rational decision making that much harder.
The speculation will slowly give way to actual facts.....but it is looking like the pilots would need to be superhuman to have avoided the outcome.
-
Pretty sure it is somewhere between 'very hard' and 'impossible' once the system has gone full nose heavy. In a manual operation, it is a LOT of turns and needs considerable effort to move
This is true, but they struggled with the airplane for quite some number of minutes. It's during this time, before the stab trim runs full nose-down, that was the time to interrupt the power to the trim system.
They were dealt a crap hand to be sure. I'm much less sure that a majority of 737 pilots would fall victim to that crap hand. I think the CVR will be enlightening to understand what was going on in their heads as they fought the airplane. The FDR and wreckage can tell us a lot of the WHAT; the CVR will help with the WHY.
-
As is common in major tragedies the end result stems from more than one problem. If the stab ran-away as a singular event I'd guess they would have responded as they should and they would still be alive. However, going back over time to the 3 previous flights, which the pilots must have been aware of, the thing of concern appears to have been BOTH a pitot/static problem and an AOA problem. So, on the day of the crash there first indications may well have been in line with what the previous pilots reported and they were very likely working that problem when the stab trim system threw them for a loop -- a stab trim system they did not fully understand because Boeing neglected to provide that information.
When you're working one or two known problems and a third rears its head you can bet there was a period of seconds at least where they tried to correlate the new problem with the existing ones. At 5000 feet they don't have that time. And, as other suggest, once the system threw the plane into a nose down attitude with, potentially, substantial down trim, they would have to manually rotate the trim wheels which, again, at 5000 feet they would have very little time.
This has the makings of a horror story!
Brian
-
The video from the Mentor pilot about the MCAS system provides some interesting info about what may have necessitated the MCAS system. The 737MAX uses larger more fuel efficient engines but do to the low ground clearance of the basic 737 design they need to mount the engine further forward and up to gain some clearance. Doing that would have changed the balance of the AC meaning that all things being equal it would need the stabilizer to be trimmed up more than previous 737 AC for a given flight condition. It's not clear to me if there were any other changes to compensate for the changed balance or if the stabilizer was changed in some way, but his mention of the larger engine and the need to alter the mounting location certainly raises some questions in my mind. In a perfect world such an alteration would necessitate other changes to return the balance -- perhaps moving some gear further aft, perhaps moving some of the fuel tanks further aft, perhaps altering the stabilizer to account for what would otherwise be a nose heavy tendency.
We are likely to see an interim report within a couple weeks but the FAA and Boeing probably know already exactly what happened. Hopefully the interim report provides some closure on this. OTH, if the engine change started a chain of other changes that lead to this Boeing could have bigger problems than the legal one they are no doubt going to face.
Brian
-
I think folks here are ignoring some key facts. First, that the emergency bulletin from Boeing does nothing but explain MCAS behavior and amplify existing procedures. Second, that the -MAX aircraft are still in service.
This strongly suggests that the aircraft are believed safe by Boeing and the FAA and that at least for the interim, the only extra training pilots need is a reminder not to let the plane get way out of trim.
I find the points that the pilots were screwed once the plane was way out of trim to be mostly irrelevant. Yes, there may not be time to recover by manually re-trimming a plane that is totally nose heavy at low altitude. That's why you don't let the aircraft into that condition. There are many conditions that you can get into that are not recoverable. You just don't let the aircraft get there.
-
I think folks here are ignoring some key facts. First, that the emergency bulletin from Boeing does nothing but explain MCAS behavior and amplify existing procedures. Second, that the -MAX aircraft are still in service.
This strongly suggests that the aircraft are believed safe by Boeing and the FAA and that at least for the interim, the only extra training pilots need is a reminder not to let the plane get way out of trim.
I find the points that the pilots were screwed once the plane was way out of trim to be mostly irrelevant. Yes, there may not be time to recover by manually re-trimming a plane that is totally nose heavy at low altitude. That's why you don't let the aircraft into that condition. There are many conditions that you can get into that are not recoverable. You just don't let the aircraft get there.
You are presupposing that the pilots chose to remain at low altitude when in a normal climb-out they would have been much higher at 13 minutes. The flight profile shows a lot of erratic up and down which I should point out is not typical of a normal climb-out.
So, it looks to me that the plane was at a dangerously low altitude and when the final push happened, or whatever the final event was, they were too low to recover even if they had the control authority to do so which is highly suspect at this point. The emergency bulletin from the FAA and the technical bulletin from Boeing would hardly be considered business as usual.
Brian
-
Actually, such alerts probably are business as usual when pilots point out a safety/training deficiency.
Until we get more info, it's just speculation that it had anything to do with the crash.
-
Actually, such alerts probably are business as usual when pilots point out a safety/training deficiency.
Until we get more info, it's just speculation that it had anything to do with the crash.
The FAA seldom uses the word "Emergency" to issue nothing out of the ordinary messages.
We should see the interim report in a few days and have a better idea of what is fact and what has been speculation.
Brian
-
Actually, such alerts probably are business as usual when pilots point out a safety/training deficiency.
Until we get more info, it's just speculation that it had anything to do with the crash.
The FAA seldom uses the word "Emergency" to issue nothing out of the ordinary messages.
We should see the interim report in a few days and have a better idea of what is fact and what has been speculation.
Brian
You missed my point. Issuing Airworthiness Directives is simply one of the things the FAA does. That includes emergency ones, of which you'll find at least a handful every year, sometimes more. They're just doing their job. It's not unusual when deciding what qualifies as an emergency is normal procedure, so it's business as usual.
-
I think folks here are ignoring some key facts. First, that the emergency bulletin from Boeing does nothing but explain MCAS behavior and amplify existing procedures. Second, that the -MAX aircraft are still in service.
This strongly suggests that the aircraft are believed safe by Boeing and the FAA and that at least for the interim, the only extra training pilots need is a reminder not to let the plane get way out of trim.
I find the points that the pilots were screwed once the plane was way out of trim to be mostly irrelevant. Yes, there may not be time to recover by manually re-trimming a plane that is totally nose heavy at low altitude. That's why you don't let the aircraft into that condition. There are many conditions that you can get into that are not recoverable. You just don't let the aircraft get there.
You are presupposing that the pilots chose to remain at low altitude when in a normal climb-out they would have been much higher at 13 minutes. The flight profile shows a lot of erratic up and down which I should point out is not typical of a normal climb-out.
So, it looks to me that the plane was at a dangerously low altitude and when the final push happened, or whatever the final event was, they were too low to recover even if they had the control authority to do so which is highly suspect at this point. The emergency bulletin from the FAA and the technical bulletin from Boeing would hardly be considered business as usual.
Brian
I'm trying to reason based on clearly stated suppositions -- none of which require that the pilots "chose to remain at low altitude."
- It is a fact that the aircraft are still in service.
- It is arguably a fact that Boeing and the FAA are extremely risk-averse. Certainly, the repercussions for another crash due to the same or a related problem would be severe.
This strongly suggests that the model is safely flyable, including under all but the most improbably failure circumstances. It also suggests that a "design fault" is not the proximate cause of this accident.
If that is true, then either:
- the accident aircraft was "broke" in some very unlikely way
OR
- the operator of the accident aircraft conducted maintenance malpractice and sent an unairworthy aircraft into service
OR
- the pilots screwed up
OR
- some combination of the above
As for why the pilots maneuvered at low altitude, we simply do not know.
As others have stated before, accidents do have multiple causes, and I expect this one will, too.
-
The root cause, the AOA or air speed sensor issue I don't think has been figured out. Another airline, Southwest had replaced a couple of AOA sensors on their 737 MAX 8's.
The problem looks like it was intermittent, on and off. Previous flights had the same problem, sensor was replaced etc.
Air Asia Crash Report : Cracked Solder Joint on Rudder Limit Circuit Board https://www.eevblog.com/forum/chat/air-asia-crash-report-cracked-solder-joint-on-rudder-limit-circuit-board/ (https://www.eevblog.com/forum/chat/air-asia-crash-report-cracked-solder-joint-on-rudder-limit-circuit-board/)
How MCAS resolves a discrepancy when you only have two sensors that can (normally) read different, it's like the redundancy engineering is shit (=not there) and the pilot is expected to cover for it.
Boeing has a backlog of 4,783 orders (https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries) for 737 MAX. for multi-billions $. I hope they don't put all this on the flight crew.
-
I hope they don't put all this on the flight crew.
I hope they put the blame on wherever the right place for the blame to go is.
If that's on the crew, so be it...
-
Actually, such alerts probably are business as usual when pilots point out a safety/training deficiency.
Until we get more info, it's just speculation that it had anything to do with the crash.
The FAA seldom uses the word "Emergency" to issue nothing out of the ordinary messages.
We should see the interim report in a few days and have a better idea of what is fact and what has been speculation.
Brian
You missed my point. Issuing Airworthiness Directives is simply one of the things the FAA does. That includes emergency ones, of which you'll find at least a handful every year, sometimes more. They're just doing their job. It's not unusual when deciding what qualifies as an emergency is normal procedure, so it's business as usual.
Well of course the FAA issues emergency reports with some frequency, there are hundreds of different AC each with issues that rare there head from time to time. FDR, like all US presidents, addresses Congress and on December 8th 1941 he did so again -- I would not describe his speech on that day as 'business as usual' even though numerous other presidents have made similar speeches. The circumstances that preceded his speech made it something of an emergency.
When the FAA issues an emergency directive its because something time critical makes it an emergency so postponing the directive isn't acceptable. When FDR declared war on Japan it wasn't business as usual even though doing so was the job of the president.
The terms 'business as usual' and 'emergency' or not synonymous -- they are in fact incongruous.
Brian
-
Actually, such alerts probably are business as usual when pilots point out a safety/training deficiency.
Until we get more info, it's just speculation that it had anything to do with the crash.
The FAA seldom uses the word "Emergency" to issue nothing out of the ordinary messages.
We should see the interim report in a few days and have a better idea of what is fact and what has been speculation.
Brian
You missed my point. Issuing Airworthiness Directives is simply one of the things the FAA does. That includes emergency ones, of which you'll find at least a handful every year, sometimes more. They're just doing their job. It's not unusual when deciding what qualifies as an emergency is normal procedure, so it's business as usual.
Well of course the FAA issues emergency reports with some frequency, there are hundreds of different AC each with issues that rare there head from time to time. FDR, like all US presidents, addresses Congress and on December 8th 1941 he did so again -- I would not describe his speech on that day as 'business as usual' even though numerous other presidents have made similar speeches. The circumstances that preceded his speech made it something of an emergency.
When the FAA issues an emergency directive its because something time critical makes it an emergency so postponing the directive isn't acceptable. When FDR declared war on Japan it wasn't business as usual even though doing so was the job of the president.
The terms 'business as usual' and 'emergency' or not synonymous -- they are in fact incongruous.
Brian
Tell that to a 911 dispatch service, where every call is an emergency, by definition, until determined otherwise. They decide which calls are real emergencys many times an hour, and also the type of emergency....and it's still business as usual FOR THEM.
This FAA directive does not compare to an FDR declaration of war at all, which I do agree was a fairly unique event. It doesn't even describe anything wrong with an aircraft. All it demands are a few updates to training manuals in reaction to information put out by Boeing. I still call that business as usual FOR THE FAA. They determined the information was sufficiently urgent and reacted like they're supposed to.
-
From https://www.nytimes.com/2018/11/27/world/asia/indonesia-lion-air-crash-.html (https://www.nytimes.com/2018/11/27/world/asia/indonesia-lion-air-crash-.html)
"""
The information from the flight data recorder, contained in a preliminary report prepared by Indonesian crash investigators and scheduled to be released Wednesday, documents a fatal tug-of-war between man and machine, with the plane’s nose forced dangerously downward over two dozen times during the 11-minute flight. The pilots managed to pull the nose back up over and over until finally losing control, leaving the plane, Lion Air Flight 610, to plummet into the ocean at 450 miles per hour, killing all 189 people on board.
"""
Eleven Minutes.
Two dozen attempts.
Sorry, there's no way these pilots did not screw up. Again, that's not to say that the undocumented MCAS system and potentially erratic behavior from potentially bad air data are not factors. But these pilots most definitely screwed up.
Also:
"""
Despite Boeing’s insistence that the proper procedures were in the handbook, also called the emergency checklist, pilots have said since the accident that Boeing had not been clear about one potentially vital difference between the system on the new 737s and the older models. In the older versions, pilots could help address the problem of the nose being forced down improperly — a situation known as “runaway stabilizer trim” — by pulling back on the control column in front of them, the pilots say.
Family members grieving after police handed over the remains of their relatives who had been aboard Lion Air Flight 610.CreditEd Wray/Getty Images
In the latest 737 generation, called the Max, that measure does not work, they said, citing information they have received since the crash. The pilots on Lion Air Flight 610 appear to have forcefully pulled back on their control columns to no avail, before the final dive, according to the information from the flight data recorder.
Capt. Dennis Tajer, spokesman for the American Airlines pilot union and a 737 pilot, said he could not comment on any aspect of the investigation. But, he said, “in the previous model of the 737, pulling back on the control column, Boeing says will stop a stabilizer runaway.”
Information provided to American Airlines from Boeing since the crash, Captain Tajer said, “specifically says that pulling back on the control column in the Max will not stop the runaway if M.C.A.S. is triggered. That is an important difference to know.”
Boeing said in its statement on Tuesday that the existing procedures covered the latest 737 model.
"""
This strongly hints at something I suggested earlier, that the written procedures, when followed, work, but that 737 pilots may have been accustomed to another procedure (pulling back on the control column) that was never the official book procedure, but which also worked on all 737's until the -MAX.
-
Two dozen attempts -
It's an automatic system switching in and out, doing retries on its own, and possibly operating with bad noisy sensor data.
You have at least four oscillators. The MCAS software, the sensor(s), the pilot, the co-pilot.
The airplane or the pilot as the ultimate authority is yet another conflict.
Investigators are saying the plane was not airworthy. It should have been grounded as soon as problems surfaced on the previous flight.
One AOA sensor had been replaced, but still a 20 degree discrepancy.
Really need the CVR to figure out all that happened.
-
Yeah it seams to me like the pilots could have easily prevented the crash if they knew what to do, even if they spent a while to diagnose the problem.
But that's not to say they are completely at fault. The finger pointing should instead be focused more towards the training the pilots ware given. Clearly they should have known about such a significant system on the aircraft.
And this doesn't just mean hammering a bunch of step by step procedures into there head on what to do if something goes wrong. They should understand why each step of the procedure is on the list and how it interacts with the problem. Yes there need to be defined procedures for dealing with faults, but in the event that the procedure does not work (Such as a fault they did not foresee) or there are multiple interacting faults that render the procedure useless they shouldn't just be repeating the procedure over and over because that's all they know to do. They should instead start thinking about why the procedure did not help and try other things.
Tho in this case the pilots surely should have noticed the big noisy trim wheels spinning all the time. If the aircraft is pitching down and trim wheels are moving that should have been an instant association of it being a trim problem. You don't need to look trough a manual for a troubleshooting procedure if you can see where the problem is. Fix it quickly and then try to figure out why it happened so that you can make a decision if its safe to continue flying to the destination.
-
Well it looks as if there is some progress in not making the poor pilots the scapegoats....
Indonesian investigators have said the Lion Air plane that crashed last month killing 189 people was not airworthy and should have been grounded.
https://www.bbc.co.uk/news/world-asia-46121127 (https://www.bbc.co.uk/news/world-asia-46121127)
-
It looks like there were similar problems on previous flights and the PIC of the previous flight eventually turned off the trim system after, I think, the third round of AND (automatic nose down) commands from the computer. So, the PIC on the previous flight appears to have done what needed to be done but the crew on the doomed flight did not.
It's also clear that there were more than one problem with airspeed and altitude as well as AOA readings being wrong.
One truly scary thing is that even the previous flight that landed safely the PIC's stick shaker was on almost the entire flight -- that had to be unnerving. Page 14 of the preliminary report shows some graphs of a few of the relevant data items during the 13 minute flight and you can see the near constant sequencing of the AND commands and the near constant manual nose up commands from the pilots and this continues all the way till the end. I'd like to know if the AND commands would still show up even of the system were turned off, I suspect they would not and that would tend to confirm they never turned it off.
By my estimate reading the charts it took less than 20 seconds for the plane to depart the flight altitude and impact the ground. Also interesting is the fact than during the final approximately 45 seconds the pitch trim position, which was a battle between the computer issued AND commands and the pilots manual pitch up commands, shows the computer continuing to issue the AND commands and the pilots continuing to issue manual nose up commands but in that final 45 seconds it doesn't look like the pilots commands had any effect. So, for about 25 seconds of that final battle the AC pitched down a bit and lost a little altitude, but in the final 20 seconds the AC pitched down more noticeably, the altitude dropped more quickly, and the airspeed increased.
The graph from the previous flight is more compressed in time owing to the much longer flight but it appears the crew fought with the computer for about 20 minutes and then there doesn't seem to be any AND commands for over an hour which kind of suggests that with the trim system turned off there are no AND commands.
So, at this point we have:
1. Numerous instrument issues covering several flights involving altitude, airspeed and AOA indications on the PIC (left) side -- this should have been fixed and confirmed fixed before passengers were allowed to fly on it
2. The previous flight reported much the same problems and issued a PAN-PAN but continued the flight after turning off the trim system -- this should have been a PAN-PAN without the option to cancel
3. The pilots of the doomed flight did not turn off the trim system and lost the fight at the end -- the pilots will get significant blame and that appears warranted
4. The maintenance activities appear to suggest the techs relied on computer self tests which seemed to indicate no problems and its not clear what level of physical inspections were done -- did they do a leak test of the pitot static lines or not
5. How was the AOA transmitter installed and does it have a registration pin or other mechanism to make sure it's installed at the right angle -- it not how did the techs set the angle on installation
Brian
-
3. The pilots of the doomed flight did not turn off the trim system and lost the fight at the end -- the pilots will get significant blame and that appears warranted
Unless:
The airline is shown not to have provided sufficient documentation or training on how to fully manage this new MCAS flight system.
:popcorn:
-
Well it looks as if there is some progress in not making the poor pilots the scapegoats....
Indonesian investigators have said the Lion Air plane that crashed last month killing 189 people was not airworthy and should have been grounded.
https://www.bbc.co.uk/news/world-asia-46121127 (https://www.bbc.co.uk/news/world-asia-46121127)
Therefore, the pilots should never have been placed in that position in the first place!
It seems to me that this thread has taken an distasteful turn towards establishing the guilt of the pilots, prior to the issuing of the full report.
-
2. The previous flight reported much the same problems and issued a PAN-PAN but continued the flight after turning off the trim system -- this should have been a PAN-PAN without the option to cancel
From a systems design standpoint, it is undesirable to create one-way doors IMO. If you make it impossible to cancel an urgency or emergency declaration, you increase the cognitive decision-making hurdle for a human to make that declaration. Aircraft and passengers have been lost from crews not declaring emergencies or otherwise clearly communicating the danger the flight was in. (Avianca 52 is the first one that comes to most people's mind, but there are others.)
There is already some resistance in non-commercial pilot community to declaring an emergency when it seems warranted. (There's another fairly vocal sub-group who argues against this position; I find myself in that group at times.) Pilots fear repercussions, paperwork, an investigation that might turn up something unrelated, etc. It's why the Aviation Safety Reporting System (https://asrs.arc.nasa.gov/) is not run by the FAA and provides immunity to crews, mechanics, and other license-holders, etc. I don't fly professionally, but I can only imagine that the pressure to not lose your job makes rule-following even more high stakes.
IMO, there's good reason for the pilot in command to be the final authority as to the conduct of the flight and would argue against taking that authority and responsibility away in normal ops, abnormal ops, or emergencies.
https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1949761/#msg1949761 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1949761/#msg1949761)
I want my pilots to be thinking "Aviate, Navigate, Communicate" (in that order of priority). I don't want "Litigate" to be on their minds at all; that can all be done at 0' AGL and 0 knots airspeed.
-
2. The previous flight reported much the same problems and issued a PAN-PAN but continued the flight after turning off the trim system -- this should have been a PAN-PAN without the option to cancel
From a systems design standpoint, it is undesirable to create one-way doors IMO. If you make it impossible to cancel an urgency or emergency declaration, you increase the cognitive decision-making hurdle for a human to make that declaration. Aircraft and passengers have been lost from crews not declaring emergencies or otherwise clearly communicating the danger the flight was in. (Avianca 52 is the first one that comes to most people's mind, but there are others.)
There is already some resistance in non-commercial pilot community to declaring an emergency when it seems warranted. (There's another fairly vocal sub-group who argues against this position; I find myself in that group at times.) Pilots fear repercussions, paperwork, an investigation that might turn up something unrelated, etc. It's why the Aviation Safety Reporting System (https://asrs.arc.nasa.gov/) is not run by the FAA and provides immunity to crews, mechanics, and other license-holders, etc. I don't fly professionally, but I can only imagine that the pressure to not lose your job makes rule-following even more high stakes.
IMO, there's good reason for the pilot in command to be the final authority as to the conduct of the flight and would argue against taking that authority and responsibility away in normal ops, abnormal ops, or emergencies.
https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1949761/#msg1949761 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg1949761/#msg1949761)
I want my pilots to be thinking "Aviate, Navigate, Communicate" (in that order of priority). I don't want "Litigate" to be on their minds at all; that can all be done at 0' AGL and 0 knots airspeed.
Yes, that is the dilemma and I know of no easy solution to it. Pilots a reticent to delay or cancel a flight for maintenance issues do to pressure from the airline to stay on schedule so they tend to fly even when conditions should dictate they not fly. You are quite right that having no choice in returning when a PAN-PAN is called might make it less likely they will call in one when deserved -- a kind of catch 22. If this were an isolated event that would be one thing, but given the previous flights with similar issues I think this escalates the problem. We are now seeing people in the aviation community stating publicly that this plane was not air worthy and I would agree with that.
As to the comment that we are being too quick to lay blame on the pilots, well, they should have known to turn of the stab trim system which suggests to me the pilots had an inadequate understanding of the flight controls and that's not acceptable for a commercial pilot, even a junior one. To be sure, the failure to clarify the difference between the 737MAX and previous versions with respect to MCAS has to be seen as a contributing factor here.
Brian
-
Two dozen attempts -
It's an automatic system switching in and out, doing retries on its own, and possibly operating with bad noisy sensor data.
You have at least four oscillators. The MCAS software, the sensor(s), the pilot, the co-pilot.
The airplane or the pilot as the ultimate authority is yet another conflict.
You will note from the QRH handbook page I posted earlier that there is nothing there about "turn the system back on and see if it does it again." You don't re-enable a dodgy flight control system. You just don't.
Investigators are saying the plane was not airworthy. It should have been grounded as soon as problems surfaced on the previous flight.
One AOA sensor had been replaced, but still a 20 degree discrepancy.
And nobody here is disagreeing with that.
"Airworthy" has a specific, technical legal meaning, and it is not "plane could not be flown." In highly colloquial language it means "the plane should not be flown." It's a huge difference. For example, if an engine fails in flight, the aircraft is obviously not airworthy, but it can still be flown and landed safely.
I have never said that the airplane was airworthy, or that there is nothing wrong with the MCAS by designed or (lack of) training. I have said that the pilots crashed a plane that unless we learn something new and very strange (like the cutout switches didn't work) could have been landed.
Accidents have multiple causes, and one of those causes is the pilots not following procedures.
Really need the CVR to figure out all that happened.
CVRs are very useful, but are only one clue among many that investigators use to determine the cause of accidents. Few GA aircraft have CVRs (or FDRs, for that matter) and yet the US NTSB routinely determines proximate and contributing causes to the vast majority of air crashes in the US. Searchable database is here https://www.ntsb.gov/_layouts/ntsb.aviation/index.aspx (https://www.ntsb.gov/_layouts/ntsb.aviation/index.aspx) and always fascinating reading.
-
We don't know the malfunctions the plane experienced.
An intermittent, something cutting in and out can confuse anyone as to what is working properly or not.
Simply switching off the trim motors leaves the stabilizer actuator where it last was- presumably set at nose down. Maybe it was switched back on to get the motors to move it back, if the sensor data smartened up. Maybe they couldn't manually crank them back in time.
Human psychology is to "blame the victim" and the pilot had 6,000hrs and co-pilot 5,000hrs so they may not have been inept. Boeing certainly is.
-
An intermittent, something cutting in and out can confuse anyone as to what is working properly or not.
These guys weren't anyone, they were airline pilots. Furthermore, as has been discussed here ad nauseum, you don't need to know what is working properly or not to get out of this situation. You need to follow the book procedures. (Aside: it turns out that the QRH procedures for runaway stab are also memory items.)
Plenty of airliners have been lost from crews trying to debug something that should have been switched off or ignored.
Simply switching off the trim motors leaves the stabilizer actuator where it last was- presumably set at nose down. Maybe it was switched back on to get the motors to move it back, if the sensor data smartened up. Maybe they couldn't manually crank them back in time.
As has already been shown, there was a lot of time, and there was a significant period of more or less level flight. It will be interesting to know if in that period they could have climbed.
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=583076)
Human psychology is to "blame the victim" and the pilot had 6,000hrs and co-pilot 5,000hrs so they may not have been inept.
This is not an argument.
Boeing certainly is.
Wait, what?
Human psychology is a lot of things, like a desire to be contrarian, or to defer to experts, or not to defer to experts, or to blame big companies, or not wanting to admit that airlines pilots might be fallible, or that 6000 hours of experience can go by without much in the way of experiences.
I think portraying the pilots as victims "before we know what happened" is also probably premature.
-
http://avherald.com/h?article=4bf90724/0008&opt=0 (http://avherald.com/h?article=4bf90724/0008&opt=0)
https://www.youtube.com/watch?v=1sZfeFJ9n0I (https://www.youtube.com/watch?v=1sZfeFJ9n0I)
-
Reading the Preliminary Report, previous flight did OK:
"Airspeed unreliable and alt disagree shown after take off. STS was also running to the wrong direction, suspected because of speed difference. Identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree."
"... the airline confirmed one of their maintenance engineers was on board of the aircraft during the accident flight. This was an "anticipatory measure" in the event of technical problems with the new aircraft."
A third opinion who may have added confusion or given wrong instructions or flipped a breaker.
I'm of the view Boeing has blood on their hands for the engineering.
One of the many questions put forth to the FAA by The Aviation Herald (http://avherald.com/h?article=4bf90724/0008&opt=0):
- Why was the MCAS permitted to operate on the base of a single AoA value showing too high angle of attacks? Why does the MCAS not consider the other AoA value?
This is a failure of the software algorithm and fault tree analysis. Can't think of one reason to keep the robot going. AoA also seems to feed corrections to airspeed and altitude.
The forum poster, about knowing to shut off a system you don't even know about:
"As a captain on Boeing 737, I feel betrayed about Boeing's statements about their documentation. Even as of now, the MCAS has not been incorporated into the FCOM, nor into the FCTM. Their press release is a shameless lie."
-
https://www.youtube.com/watch?v=zfQW0upkVus (https://www.youtube.com/watch?v=zfQW0upkVus)
https://www.youtube.com/watch?v=1sZfeFJ9n0I (https://www.youtube.com/watch?v=1sZfeFJ9n0I)
-
Reading the Preliminary Report, previous flight did OK:
"Airspeed unreliable and alt disagree shown after take off. STS was also running to the wrong direction, suspected because of speed difference. Identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree."
"... the airline confirmed one of their maintenance engineers was on board of the aircraft during the accident flight. This was an "anticipatory measure" in the event of technical problems with the new aircraft."
A third opinion who may have added confusion or given wrong instructions or flipped a breaker.
This is just the thing. It was poor aeronautical decision making to attempt to figure out what is going, and there was no need to figure out what what going on. None. Zip. Nada. What needed to happen was for the pilots to quickly execute three memory items, then assess the situation further after the airplane is under full control.
I mean, look at the situation you're describing. They had a tech on board to help debug a system they knew was misbehaving that directly affected safety of flight, with revenue passengers in the back. What kind of ADM is that? And that decision was made on the ground. And given that they were anticipating stab problems, you'd think the crew would be spring-loaded to execute the runaway trim procedures at the first sign of trouble. But it is obvious they never did this. Maybe we'll find out from the CVR why. If it is because they thought they could figure it out, it will be a textbook case of poor ADM.
I'm of the view Boeing has blood on their hands for the engineering.
One of the many questions put forth to the FAA by The Aviation Herald (http://avherald.com/h?article=4bf90724/0008&opt=0):
- Why was the MCAS permitted to operate on the base of a single AoA value showing too high angle of attacks? Why does the MCAS not consider the other AoA value?
I tend to agree that Boeing probably screwed up. That doesn't mean the pilots didn't screw up. This is not unlike AF447 where a bad pitot heater design allowed the pitot system to fail, which caused the computer to stop providing envelope protection -- but that did not force the pilot to execute a zoom climb and then stall the aircraft.
The forum poster, about knowing to shut off a system you don't even know about:
"As a captain on Boeing 737, I feel betrayed about Boeing's statements about their documentation. Even as of now, the MCAS has not been incorporated into the FCOM, nor into the FCTM. Their press release is a shameless lie."
The pilot is being misleading, as you do not have to shut off a system you don't know about. You have to shut off the stab trim system.
I think Boeing's position on this is pretty clear: if you follow the procedure, it doesn't matter. Some pilots are saying it does matter. We'll find out.
-
Update today , the CVR is recovered, buried 8 meters underneath the mud in about 30 meters deep.
https://www.reuters.com/article/us-indonesia-crash-recorder/indonesian-officials-say-crashed-lion-air-jets-cockpit-voice-recorder-found-idUSKCN1P808C?il=0 (https://www.reuters.com/article/us-indonesia-crash-recorder/indonesian-officials-say-crashed-lion-air-jets-cockpit-voice-recorder-found-idUSKCN1P808C?il=0)
Local news mentioned they used ROV with side scan sonar, magnetometer to find it.
(https://akcdn.detik.net.id/community/media/visual/2019/01/14/ce31cbf1-2fb1-4fec-b5d5-804d5994d659.jpeg?w=650&q=90)
-
Update today , the CVR is recovered, buried 8 meters underneath the mud in about 30 meters deep.
https://www.reuters.com/article/us-indonesia-crash-recorder/indonesian-officials-say-crashed-lion-air-jets-cockpit-voice-recorder-found-idUSKCN1P808C?il=0 (https://www.reuters.com/article/us-indonesia-crash-recorder/indonesian-officials-say-crashed-lion-air-jets-cockpit-voice-recorder-found-idUSKCN1P808C?il=0)
Local news mentioned they used ROV with side scan sonar, magnetometer to find it.
That is good news and hopefully this will clear up the actions the pilots made and provide an insight into the sequence of actions they took. The great question is: why did they not turn of the Stab Trim and did they talk about doing so.
The upside to the crash, if there is an upside, is that there can't be a single 737MAX pilot that does not now know what MCAS is and how and when to power off the Stab Trim.
Brian
-
Hopefully the recording data is still ok, as from the look, the outer physical unit looks badly wrecked.
-
Hopefully the recording data is still ok, as from the look, the outer physical unit looks badly wrecked.
WOW, had not looked at the pic before, but damn that thing is busted up. The odd thing is you would expect the damage to be less with an impact with water versus land, but at the speed it must have hit the water it might as well have been land.
Brian
-
Well crash landings on water are not actually any better than on land.
At the sort of speeds an impact with water makes it feel pretty much as hard as rock. But with the extra problem of also being very slippery and easy to dig into at the same time, if something actually does poke down into the water it experiences a massive amount of drag that slows it down very fast. So when something like the end of a wing touches the water surface the whole plane will suddenly be jerked into a sharp turn before the wing can't take it anymore and tears apart. Once the plane stops its not air tight anymore so it will just sink like a rock and if you do make it out alive you are now swimming in the middle of the sea with no land in sight while the top layer of water if full of kerosine.
Then again such a noise first crash straight into land would be impossible to survive too. But a more controlled crash landing is certainly more survivable on a open field of land rather than at sea.
-
Hopefully the recording data is still ok, as from the look, the outer physical unit looks badly wrecked.
WOW, had not looked at the pic before, but damn that thing is busted up. The odd thing is you would expect the damage to be less with an impact with water versus land, but at the speed it must have hit the water it might as well have been land.
Brian
See for youself for.more.photos ...
https://m.detik.com/news/foto-news/d-4383483/penampakan-cvr-lion-air-pk-lqp-yang-akhirnya-ditemukan
-
Data capsule is intact, so should read out perfectly well once taken apart. Broke off the electronics section as designed. Just have to hope the data is not degraded from all the overwrites it has had.
-
... Just have to hope the data is not degraded from all the overwrites it has had.
Do the math... it was a new plane, so not many running hours (flight hours plus ground running). I believe they record at least the last 30 minutes, so 2 writes per hour... Not a problem, even for ordinary consumer flash.
-
124 minutes of voice recordings from the CVR transcribed, including the final 15 minutes.
"Lion Air crash investigators will not release the contents of the flight's black box voice recordings until August or September."
Another 9 months before it gets released :-//
NTSB has their investigation on hold due to the US Gov't shutdown.
-
Hopefully the recording data is still ok, as from the look, the outer physical unit looks badly wrecked.
WOW, had not looked at the pic before, but damn that thing is busted up. The odd thing is you would expect the damage to be less with an impact with water versus land, but at the speed it must have hit the water it might as well have been land.
Brian
See for youself for.more.photos ...
https://m.detik.com/news/foto-news/d-4383483/penampakan-cvr-lion-air-pk-lqp-yang-akhirnya-ditemukan
Water is practically as hard as concrete when impacted at high speed. An airliner that hits water or ground going ~500mph pretty much shatters into tiny particles. It's something a lot of conspiracy theorists fail to understand, expecting to see recognizable airplane wreckage.
-
Another 737 MAX:
https://www.youtube.com/watch?v=I3FDm3s2_VY (https://www.youtube.com/watch?v=I3FDm3s2_VY)
-
The pilot is being misleading, as you do not have to shut off a system you don't know about. You have to shut off the stab trim system.
I think Boeing's position on this is pretty clear: if you follow the procedure, it doesn't matter. Some pilots are saying it does matter. We'll find out.
If you can internalize why a system works in the way it does it's generally much easier to work with it than just having a bunch of arcane rules. Now at some point the mental model can become too complex too, but that's clearly not the case here.
Just that if Boeing actually changes the manual at this point it's admitting partial guilt, so they feel they can't. So they need to be forced to and penalized for avoiding taking some responsibility.
-
Another 737:
Well, the 737 product line as a whole has possibly the best overall safety record, statistically speaking, of any airliner. (There are 1200 737's in the air at any given moment!!!)
But for two 737 MAX's to crash like this in just a few months, that is very odd indeed.
-
Boeing's MCAS software update, as an emergency measure by the FAA and Boeing, deployment delayed for months. It was due January but now maybe after April 2019.
"...Boeing is examining whether the anti-stall system should also check data from the second probe before engaging"
-
Too soon to say what happened for sure, but the similarities with the Lionair crash has to point a finger at MCAS as a logical place to look at. The FDR will be revealing but as with the Lionair crash I think the CVR may well be more revealing if crew response to a problem played a role. If it turns out that this is another case of MCAS taking over and the pilots not knowing what to do then Ethiopian Air has some explaining to do on the pilot training program. If the pilots fought the MCAS system for 5 minutes and didn't turn off the Stab Trim then whatever blame Boeing gets, and probably deserves, should be shared equally with the pilots and the airline. Can there be a 737 Max pilot that does not know about MCAS and how to respond when it acts up anywhere in the world at this point?
Brian
-
At this point, if it's a Boeing (737 MAX) I ain't going.
-
When i saw the news i quickly remembered this very thread. The similarities between the crashes are quite striking.
Id imagine things are getting quite tense among the upper management at Boeing now.
-
Flightradar24 data regarding the crash of Ethiopian Airlines flight 302:
https://www.flightradar24.com/blog/flightradar24-data-regarding-the-crash-of-ethiopian-airlines-flight-302/ (https://www.flightradar24.com/blog/flightradar24-data-regarding-the-crash-of-ethiopian-airlines-flight-302/)
What-is-the-boeing-737-max-MCAS?
https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/ (https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/)
-
As a pilot I can say an Angle of Attack (AOA) indicator is a suitable safety measure for when the pitot tube is clogged and you have no airspeed indication. The main thing a pilot is using the airspeed indicator for is to set the Angle of Attack to a safe measure to avoid a stall (lots of other stuff, too, but that is the one that usually kills you).
The 737 MAX has had bulletins on its AOA indicator. So perhaps it was multiple sensor failure.
A pilot is trained to cross check data from multiple sensors during IFR flight. We learn how to identify various failures. I can tell you from various in-flight failures (instrumentation as well as single engine loss of power) that this does take a moment to identify the issue, but the first thing I do is pitch forward (nose down) to decrease my AOA when diagnosing issues. If this means you can't hold your altitude immediately declare and emergency and work from there. Rule one of being a pilot is FLY THE AIRPLANE.
I feel like a lot of commercial pilots are so concerned about ATC deviations and possible career ramifications that they hesitate to declare emergencies or take emergency action prior to declaring.
-
Flightradar24 data regarding the crash of Ethiopian Airlines flight 302:
https://www.flightradar24.com/blog/flightradar24-data-regarding-the-crash-of-ethiopian-airlines-flight-302/ (https://www.flightradar24.com/blog/flightradar24-data-regarding-the-crash-of-ethiopian-airlines-flight-302/)
I do not understand the graphs and they seem contradictory to me.
Compare altitude with rate of climb. When the aircraft is climbing it should be gaining altitude and yet at first it gains altitude while not climbing and later it climbs without gaining altitude. Maybe the two lines are shifted with respect to each other? Or am I misunderstanding anything?
-
I do not understand the graphs and they seem contradictory to me.
Yes, and I don't know what's going on:
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=673662;image)
Here's the chart of the previous 737-MAX crash https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/ (https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/) It says "derived Vertical speed", I don't know in what sense is the word derived used. Most of it makes sense but in a few spots the data is contradictory too.
-
The CVR has been found. Hopefully it's not too damaged.
-
Slightly OT, but is it the case that one recorder only logs voice, while the other only logs data?
Is there a compelling reason why a single recorder can't log both? Or why both recorders don't each log everything?
-
Some level of redundancy I guess. I'm not sure if modern CVRs still use tape rather than the Flash used in the FDR. You'd hope that, with advancing technology, they'd move to two recorders, each recording both voice and data.
I suppose there is a huge amount of testing, not to mention backward compatibility involved in bringing new black boxes into service.
EDIT: It looks as if they are made http://www.aircpa.com/product/combined-cvr-fdr-wembedded-rips-cvfdr-145r/ (http://www.aircpa.com/product/combined-cvr-fdr-wembedded-rips-cvfdr-145r/) I found some reference to them being used on the 787 too.
-
I'm guessing the reason for separate black box recorders is historical
Back when these things ware analog and used magnetic tape meant it was likely easier to build one optimized for mono audio while another box was designed for lower bandwidth sensor data but with many channels, Perhaps using multitrack heads or stuffing all the channels into one track using modulation and multiplexing.
Now that its all flash it doesn't really make a difference, but yeah id imagine its not easy to change it due to all the paperwork needed to do so. All existing aircraft also have wiring harnesses prepared for this kind of dual black box setup and likely couldn't very easily be upgraded to the new standard.
-
Gebeyehu Fikadu, an eyewitness to Sunday's fatal crash about two-hour drive south of the Ethiopian capital of Addis Ababa, told CNN that the plane was "swerving and dipping" and belching smoke as it came down.
"I was in the mountain nearby when I saw the plane reach the mountain before turning around with a lot of smoke coming from the back and then crashed at this site," said the 25-year-old, who was collecting firewood on the mountain with three other locals when it happened.
"It crashed with a large boom. When it crashed luggage and clothes came burning down.
"Before it crashed the plane was swerving and dipping with a lot of smoke coming from the back and also making a very loud unpleasant sound before hitting the ground."
https://edition.cnn.com/world/live-news/ethiopian-airlines-plane-crash/index.html#h_f2affeaf6e5854fe7c4236c32490db45
-
FDR now also found.
-
I'm guessing the reason for separate black box recorders is historical
Back when these things ware analog and used magnetic tape meant it was likely easier to build one optimized for mono audio while another box was designed for lower bandwidth sensor data but with many channels, Perhaps using multitrack heads or stuffing all the channels into one track using modulation and multiplexing.
Now that its all flash it doesn't really make a difference, but yeah id imagine its not easy to change it due to all the paperwork needed to do so. All existing aircraft also have wiring harnesses prepared for this kind of dual black box setup and likely couldn't very easily be upgraded to the new standard.
What's kinda crazy is that, due to magnetic tape (and paper) being too sensitive to heat, pre-Flash CVRs and FDRs used metal tape (and in some really old ones, wire) as the magnetic recording medium. Older FDR models didn't even do it magnetically, but rather used styluses that engraved the data onto wide metal tape -- just like a polygraph or seismograph, except with a stylus instead of a pen.
I'm actually kinda surprised that we even still rely on CVRs and FDRs, since satellite-based, real-time, server-side logging is available. It is used by some airlines. Streaming all that means that you have it instantly, and it doesn't matter whether you find the black boxes. (I'm sure there are occasions where streaming fails, so I wouldn't say to get rid of black boxes entirely, but just to relegate them to being backups.)
-
Gebeyehu Fikadu, an eyewitness to Sunday's fatal crash about two-hour drive south of the Ethiopian capital of Addis Ababa, told CNN that the plane was "swerving and dipping" and belching smoke as it came down.
"I was in the mountain nearby when I saw the plane reach the mountain before turning around with a lot of smoke coming from the back and then crashed at this site," said the 25-year-old, who was collecting firewood on the mountain with three other locals when it happened.
"It crashed with a large boom. When it crashed luggage and clothes came burning down.
"Before it crashed the plane was swerving and dipping with a lot of smoke coming from the back and also making a very loud unpleasant sound before hitting the ground."
https://edition.cnn.com/world/live-news/ethiopian-airlines-plane-crash/index.html#h_f2affeaf6e5854fe7c4236c32490db45
If there was smoke coming from the plane, and particularly if it wasn't clearly identified with and engine, could completely change the picture of what happen and surely opens the door to something nefarious going on. If there was an onboard fire or cabin or cargo hold explosion it's quite possible we would have seen a similar flight profile and ultimate crash. But, as with so many cases, eye witness accounts are often the least trust worthy even when a competent person is involved and the average passer by is next to useless in these maters.
It's also possible that the pilots were jacking the throttles around as a consequence of an MCAS takeover and it is possible that could produce some smoke.
If the reports are true that both the CVR and FDR have been found and they are in decent shape we should get a preliminary report pretty soon given the stand-down ordered for more than 100 737 Max AC -- if there was evidence that the problem wasn't MCAS and was a cargo fire then that should permit the grounded AC to resume flying.
Brian
-
I do not understand the graphs and they seem contradictory to me.
Yes, and I don't know what's going on:
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=673662;image)
Here's the chart of the previous 737-MAX crash https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/ (https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/) It says "derived Vertical speed", I don't know in what sense is the word derived used. Most of it makes sense but in a few spots the data is contradictory too.
I don't know what measurements are actually being tracked by flightradar24 but if it is just GPS coordinates (or "pings") every once in a while, it would have a location in 3D space which includes coordinates and altitude. The "derived" part would be vertical speed, which would essentially be the derivative of the altitude measurement (i.e. the delta or slope of the altitude). So if you see your altitude changing by 100 feet every minute... 0, 100, 200, 300, 400... you have a gradual slope in altitude, during that time the "derived" vertical speed would be a constant 100 per minute. When it flattens to 400, 400, 400, 400... you would see vertical speed become 0 on that part of the altitude curve (i.e. flat or zero slope). The ground speed would therefore simply be the change in the X,Y (GPS) coordinates. Now since we are looking at 3D vectoring there would be more complex way to determine airspeed because you would then include the vertical in that as well with the ground speed, do XYZ vector and determine actual velocity through air. Then again, there is also wind that complicates things. I'm not sure how flightradar is tracking things but I'm sure the "blackbox" on the airplane has the detail they will need to determine what happened.
Not being a pilot, I am actually surprised at how much of the flight is "fly by wire" and relying on instruments. I guess at that level of airplane you need to... I can only imagine flying a Cessna, looking out the window, feeling the G-forces and wind and hearing the engine noise to determine whether I am properly flying the thing. Someone mentioned earlier in the thread that pilots want to stay in that flight path regardless as deviation may cause disciplinary actions, instead of just FLYING THE PLANE no matter where and how and at what speed and altitude.
-
Not being a pilot, I am actually surprised at how much of the flight is "fly by wire" and relying on instruments.
Let's not go down this rabbit hole again, like we did way earlier in this thread. The 737 is NOT a fly by wire aircraft, and uses hydraulic control systems. That includes the 737 MAX, with the exception of the spoiler system. The term "fly by wire" means that the interface between the pilots controls is interpreted and converted to electronic signals transmitted to the actuators for flight surfaces via signal wires.
As for paying attention to instruments, that's part of the job, but doesn't mean they aren't looking and feeling as well. If you're suggesting that the pilots were unaware they weren't climbing properly and had failed to notice they never got more than a few hundred feet off the ground before running into rising terrain, that is clearly not the case. Even passengers would notice that difference in "feel" from a normal takeoff, without looking out the windows.
-
Not being a pilot, I am actually surprised at how much of the flight is "fly by wire" and relying on instruments.
Let's not go down this rabbit hole again, like we did way earlier in this thread. The 737 is NOT a fly by wire aircraft, and uses hydraulic control systems.
Yes thank you for the correction and clarification, as I misspoke about the "fly by wire". I am not sure how the controls and the mechanics interconnect, so I used the term incorrectly to refer to this. What I was trying to get at was whether in the evolution of flight training from smaller aircraft to larger ones, we see a gradual diminishing in flying relying on feedback directly from what you see, hear and feel, and more reliance on instrumentation and indicators? Is this due to the level of experience needed by the pilot, the conditions (night time, no visibility) that is expected in training, the larger aircraft (versus a small one which perhaps may respond more quickly to external forces and changes)? Not being a pilot I am not sure why someone mentioned earlier in the thread that when something starts going "wrong" whether going off-road (so to speak) with the plane and just flying it based on basic principles and "gut" feedback and ignoring the instruments is practical or just not possible in a large modern airplane.
-
Flying by feel can become very misleading actually.
You can feel fast changes in speed or orientation very well because of feeling forces on your seat and the "biological gyroscope" in your ear. But both of these don't notice any slow long term change as you sort of get used to it along the slow change. Just like real gyroscope sensors our biological ones have trouble with long term drift.
Having no visibility and not looking at the instruments you can easily fly banked to the right 30 degrees but being absolutely certain you are perfectly level. If the bank angle builds up very slowly you just get used to it and take it as a new "zero reference" had someone corrected it back to level quickly you would swear that you are banking the other way rather than straightening out. What makes things worse with planes is that banks are used to steer left and right, because of this the acceleration from the turn is always pointing down. A bubble level in a plane would stay centered in the middle on a correctly executed turn. You don't feel yourself pulled to the side at all, the only clue is that looking out the window you can see the sky looks sideways.
-
Flying straight by eye is one thing, not as hard as flying level by eye.
The tall dashboard in the Cessna's I've had a play in are high for a reason when you're flying VFR so to help you keep a cockpit horizon to keep somewhere level.
First I thought the altimeter was the thing to watch all the time but no, you only check it from time to time to keep well in your allotted airspace and use the top of the dash to some distant point to keep yourself close to level flight.
Even when doing a 180 to line up for landing, if it was dark you'd have no idea you were both descending and turning without instruments, as the bodily feedback was so minimal unless you really cranked it over.
When my daughter did her initial IFR training they wore like a low brimmed hat so to not be able to see out the windscreen and so have to rely on instruments.
-
Many countries (also ours) is closing their airspace for 737-max planes.
This is I think the first time this is going on in so many countries ? :-//
-
Boeing: UK joins wave of countries grounding the 737 Max
https://www.bbc.com/news/world-asia-47536502?intlink_from_url=https://www.bbc.com/news/topics/cv06837xl7lt/ethiopian-airlines-crash&link_location=live-reporting-story (https://www.bbc.com/news/world-asia-47536502?intlink_from_url=https://www.bbc.com/news/topics/cv06837xl7lt/ethiopian-airlines-crash&link_location=live-reporting-story)
The UK's Civil Aviation Authority (CAA) has banned the Boeing 737 MAX from operating in or over UK airspace "as a precautionary measure".
[...]
In the aftermath of the accident, Ethiopia, Singapore, China, France, Ireland, Germany, Australia, Indonesia and Malaysia have all temporarily suspended the 737 Max.
-
(emphasis below is mine)
Update today , the CVR is recovered, ...
That is good news and hopefully this will clear up the actions the pilots made and provide an insight into the sequence of actions they took. The great question is: why did they not turn of the Stab Trim and did they talk about doing so.
The upside to the crash, if there is an upside, is that there can't be a single 737MAX pilot that does not now know what MCAS is and how and when to power off the Stab Trim.
Brian
Sigh. Apparently not yet.
-
Well the heat on Boeing is being turned up to eleven. The EU is suspending all 737 Max flights beginning at 3PM ET.
Flight attendant union now calls for 737 MAX fleet to be grounded.
Senator asks American, Southwest and United to voluntarily to ground their Boeing 737 MAX 8s.
Austria, Poland and Italy are the latest to ground 737 MAX 8s.
Turkish Airlines grounds all Boeing 737 MAX aircraft.
Netherlands suspends Boeing 737 MAX 8 aircraft.
Iceland and Germany join list of countries deciding to ban 737 MAX 8 aircraft.
France's aviation authority bans Boeing 737 MAX aircraft from its airspace.
Meanwhile...
Boeing says it has "full confidence" in its 737 MAX jets and isn't issuing new guidance
Brian :popcorn:
-
Boeing shares plummeting like MAX several days in a row.........(terrible as a joke but as a fact is true).
Boeing claims MCAS new software version to come.
-
Boeing claims MCAS new software version to come.
An OTA update?
-
Boeing claims MCAS new software version to come.
An OTA update?
Good greif noooo, after the crash.
-
Boeing claims MCAS new software version to come.
An OTA update?
I really hope there's no way an OTA update could happen and expose the AC to hacking potential. Imagine the next Bin Laden with a team of hackers devising a new "Planes Plan" with no risk to any of his people.
I have to believe the update would need to be done by Boeing employees and only Boeing employees and only on the ground.
Brian
-
I would be less worried about terrorists than by all the other things that could go wrong with an OTA update. I've seen countless gadgets bricked by that sort of thing going wrong. Pretty sure they have the sense not to design such a mechanism into an aircraft though.
As a side note, I really wish the ease of updating we have today had never been developed. It's sold on the benefits of being able to easily fix bugs and add features in the future. Unfortunately what it has done is enabled a mentality of ship the minimum viable product and finish it "later". Sorry but when I buy something I expect it to work as advertised out of the box, and to keep working until I decide to replace it. I'm not going to buy something based on promises of features to be added at some later date, and I don't want updates introducing new bugs and breaking/removing/changing features I use.
-
As a side note, I really wish the ease of updating we have today had never been developed. It's sold on the benefits of being able to easily fix bugs and add features in the future. Unfortunately what it has done is enabled a mentality of ship the minimum viable product and finish it "later". Sorry but when I buy something I expect it to work as advertised out of the box, and to keep working until I decide to replace it.
I agree fully. Unfortunately this is now common practice in consumer electronics because the product development cycles has been cut at least in three compared to ten years ago.
New features are a must have in time for the next product launch otherwise the marketing team has to wait for the next time window which often is half a year or even one year and by then the competition will already sold their unfinished products.
I just hope for all our sake this is not the case for the firmware in new aircrafts.
-
If Boeing is to assure everyone that the 737 MAX 8 is safe, they can simply get their CxO on board one with its Pitot tube clogged and AoA sensor disabled, then hire two average 737 pilots that do not have intimate knowledge on MCAS and its quirks to fly it. I'm sure news agencies worldwide will report this intrepid action and clear their name.
That's better than any spokesmen.
If Boeing were a Japanese company then doing what you said would be almost likely but very few companies act as the Japanese do in situations like this. In fact, as the Tepco Fukushima thing demonstrated, the Japanese way isn't always practiced by the Japanese.
So the rumor is that Boeing has a MCAS update coming -- when might that be. The problem Boeing has here is that no matter what they do they are going to be sued big time for both crashes. On the one hand, they might have preferred this second accident never happened so they could distance themselves from the Lionair crash and a year from now if they rolled out an update they might uncouple it from the Lionair incident and, perhaps, avoid the worst of the legal problems, but with this second accident they will now have to update MCAS and soon and it will be hard for them to prove it was just an incidental thing. Not doing something will end the 737 MAx program right now.
Boeing is going to be eaten alive by lawyers and if the Lionair case was bad this new one probably triples what they can expect to pay and it could be 10X. Yes yes, we don't know the MCAS was involved in this new case, not for sure anyway, but even professionals in the airline industry are pretty sure MCAS played a role. It's not out or reach for this to take down Boeing altogether leaving only one major player in the game. I doubt that will happen, but it is certainly a possibility. The saving grace for Boeing may be there military contracts and the fact that those military relationships may make them 'to important to fail' by the US government. Airbus would love that to happen as would many others in the world with a hardon against the USA, but as touch and go as it might be I don't see them fold because of this.
Brian
-
your analogy to Fukushima stumbles.
https://gizmodo.com/boeing-promises-to-release-software-update-for-737-max-1833224836
https://boeing.mediaroom.com/news-releases-statements?item=130402
For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.
-
your analogy to Fukushima stumbles.
https://gizmodo.com/boeing-promises-to-release-software-update-for-737-max-1833224836
https://boeing.mediaroom.com/news-releases-statements?item=130402
For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.
I think you misunderstood my reference to Fukushima -- it wasn't about an malfeasance by Boeing but that the execs at Tepco displayed an un-Japanese practice of not putting your skin on the line as blueskull alluded to.
Boeing has, prior to this latest crash, promised an update but has been less than forthcoming about when it will be delivered. This new incident will not permit them to delay this and it also makes it harder for them to uncouple the update with the crashes that happened.
Brian
-
Well thats what i have doubts about a "un japanese action". I think Japanese is as much as cowards as rest of us are when it comes to self preservation, all this CEO crying and apologizing in public a silly show based on wicked ideas about cultural behavior, send them to jail instead. :popcorn:
-
A bug in the MCAS that pushes the nose down too far, overriding the pilot's nose up command, is that it, then, it seems?
-
I really hope there's no way an OTA update could happen and expose the AC to hacking potential. Imagine the next Bin Laden with a team of hackers devising a new "Planes Plan" with no risk to any of his people.
I have to believe the update would need to be done by Boeing employees and only Boeing employees and only on the ground. Brian
imagine CIA instead!
-
Well thats what i have doubts about a "un japanese action". I think Japanese is as much as cowards as rest of us are when it comes to self preservation, all this CEO crying and apologizing in public a silly show based on wicked ideas about cultural behavior, send them to jail instead. :popcorn:
In the wake of the JAL 123 crash the president of the airline resigned, an engineer and the maintenance manager killed themselves. I don't think that would happen had it been a US based airline for example.
-
In the wake of the JAL 123 crash the president of the airline resigned, an engineer and the maintenance manager killed themselves. I don't think that would happen had it been a US based airline for example.
Nor an European, they would try squirm them self out like the Lufthansa CEO did when Germanwings crash hapend.
JAL 123 crash voice recording is something to listen to, how the pilots doing all they can to save the rudder fin less oscillating 747. :phew:
Then the rescue team on the ground screwed things up so some could had been saved died.
cockpit voice recording
https://www.youtube.com/watch?v=Xfh9-ogUgSQ (https://www.youtube.com/watch?v=Xfh9-ogUgSQ)
-
Boeing has, prior to this latest crash, promised an update but has been less than forthcoming about when it will be delivered. This new incident will not permit them to delay this and it also makes it harder for them to uncouple the update with the crashes that happened.
No way to avoid that.
-
Boeing has, prior to this latest crash, promised an update but has been less than forthcoming about when it will be delivered. This new incident will not permit them to delay this and it also makes it harder for them to uncouple the update with the crashes that happened.
No way to avoid that.
Nope ... There's going to be a generation of lawyers able to retire earlier than expected.
Brian
-
I can't see how these could be isolated incidents. I wonder if other unreported incidents have occurred that were dealt with relatively uneventfully by following the manual?
Is there a mandatory reporting procedure for dealing with anomalies in-flight?
While being completely different, from a functionality perspective this doesn't seem that far off the 737 rudder reversal issues.
-
Is there a mandatory reporting procedure for dealing with anomalies in-flight?
Yes, pretty much everything abnormal in aviation requires some kind of reporting, although the consequences of not doing so may vary depending on the countries involved.
The demand for "quick fix" software updates runs squarely into the legally mandated development process for mission-critical avionics software. This is combined with the slow release of diagnostic information from accident investigations. Boeing presumably gets access to raw data prior to public release, but it still takes time to digest correctly and remains subject to NTSB (and other agency) recommendations/demands that may or may not have been met by premature action.
https://en.wikipedia.org/wiki/Avionics_software#Regulatory_issues
None of that can be skipped, so it takes time. Doing it right trumps doing it fast.
-
I can't see how these could be isolated incidents. I wonder if other unreported incidents have occurred that were dealt with relatively uneventfully by following the manual?
Is there a mandatory reporting procedure for dealing with anomalies in-flight?
While being completely different, from a functionality perspective this doesn't seem that far off the 737 rudder reversal issues.
Well, of course, we'll know when we know. But I am starting to think that they could just be isolated incidents. First, I just can't wrap my head around the idea that, given what happened with Lionair, that any 737 driver, including this crew, would be absolutely primed to handle a runaway stab problem by putting the system in cutout as per the flight manual. It just defies reason that the crew would find itself unprepared for a LionAir type scenario. The second reason is that an eyewitness claims he saw smoke on the way down.
Anyway, all speculation at this point. They have the CVR and FDR, so they'll know soon enough.
-
Is there a mandatory reporting procedure for dealing with anomalies in-flight?
Yes, pretty much everything abnormal in aviation requires some kind of reporting, although the consequences of not doing so may vary depending on the countries involved.
The demand for "quick fix" software updates runs squarely into the legally mandated development process for mission-critical avionics software. This is combined with the slow release of diagnostic information from accident investigations. Boeing presumably gets access to raw data prior to public release, but it still takes time to digest correctly and remains subject to NTSB (and other agency) recommendations/demands that may or may not have been met by premature action.
https://en.wikipedia.org/wiki/Avionics_software#Regulatory_issues
None of that can be skipped, so it takes time. Doing it right trumps doing it fast.
Yes and that's the quandary that Boeing is in right now -- they may have a handle on the problem and a solution to it but the process, which is not only understandable but necessary, may necessitate taking longer to jump through those hoops. My guess is that Boeing was aware of the potential for a problem before they shipped the first one but they must have felt the runaway stabilizer protocol was sufficient. I have to say the fact that the system can command a nose down trim hen so close to the ground on only the data from one side and without reference to the other side seems criminal to me -- when the system is in doubt don't take control from the pilots.
I can see two fixes for this: the first, the bandaid, will be software only or if hardware is includes the hardware changes will be minor; the second one may require a third system to monitor both sides and act as an arbiter if there's a difference. If one side could see what the other side sees from the beginning I fail to see how they could have designed the software NOT to look at the other side and not command nose down at low altitude if there's a disagreement.
Another aspect of this that boggles my mind is that the system puts stall prevention above everything, even a steep nose down attitude at low altitude. And, once again, the idea that this AC isn't fly-by-wire is a distinction without a difference. If the computer can interfere with the pilots control actions and override them it's kind of hard to say this isn't fly-by-wire now is it.
Brian
-
I can't see how these could be isolated incidents. I wonder if other unreported incidents have occurred that were dealt with relatively uneventfully by following the manual?
Is there a mandatory reporting procedure for dealing with anomalies in-flight?
While being completely different, from a functionality perspective this doesn't seem that far off the 737 rudder reversal issues.
Well, of course, we'll know when we know. But I am starting to think that they could just be isolated incidents. First, I just can't wrap my head around the idea that, given what happened with Lionair, that any 737 driver, including this crew, would be absolutely primed to handle a runaway stab problem by putting the system in cutout as per the flight manual. It just defies reason that the crew would find itself unprepared for a LionAir type scenario. The second reason is that an eyewitness claims he saw smoke on the way down.
Anyway, all speculation at this point. They have the CVR and FDR, so they'll know soon enough.
I saw that reference to a witness claiming smoke, but as I mentioned, witness testimony is the lowest form of evidence and its common for a dozen witness to the same event describe them a dozen different and incompatible ways. People are dreadful witnesses...
Brian
-
I don't understand why the FAA doesn't ground the 737, as many other countries do. Do they wait for a 3rd crash to be sure that there is something wrong with the plane?
-
I don't understand why the FAA doesn't ground the 737, as many other countries do. Do they wait for a 3rd crash to be sure that there is something wrong with the plane?
Me neither, better safe than sorry, esp. when there are 100+ lives involved each incident.
It "feels" like there are some business/politic entanglements there ;)
But on the other hand since there is no final outcome of the investigation yet they can only take preventive measures.
It could well be a pilot error in one of the cases due to the new plane, or is there already some hard evidence out there ?
-
https://www.youtube.com/watch?v=1XCU__OEftU (https://www.youtube.com/watch?v=1XCU__OEftU)
-
Right, I think the video explains it. In short, and what I've read elsewhere: The jet engines were not designed for this plane, but they used it anyway, maybe to save some money. So it doesn't really fly stable without software correction, because they are mounted at the wrong position. The software depends on sensor inputs, and I've read these AOA sensors are not redundant and can fail. If this happens, the pilot has to understand that this is the problem, and then do 3 non-obvious steps to counteract that the nose dips and that it falls out of the sky.
-
There has to be a bug in the MCAS software because in the previous crash both air speed (pitot) and AoA sensors had malfunctioned in the flight previous to the crash and were replaced. Four new sensors can't fail all at once twice in a 5 months period. Either the MCAS software has a bug and misreads the sensors data, like a bad pointer or something, or if it really was a sensor malfunction, the MCAS should disengage and put an alarm to the pilot when the data it's getting from the sensors does not make sense, instead of say nothing and keep pushing the nose down.
-
I just hope all the USA pilots are by now well trained to disable in a sec that bloody MCAS POS.
-
Canada has now banned the 737 Max as well.
-
As of today the following countries has grounded the 737 MAX.
Argentina,Australia,Austria,Belgium,Brazil,Bulgaria,Cayman Islands,China,Canada,Croatia,Cyprus,Czech Republic
Denmark,Estonia,Ethiopia,Finland,France,Germany,Greece,Hungary,Iceland,India,Indonesia,Ireland,Italy,Latvia
Liechtenstein,Lithuania,Luxembourg,Malaysia,Malta,Mexico,Mongolia,Morocco,Netherlands,Norway,Oman,Poland
Portugal,Romania,Singapore,Slovakia,Slovenia,South Africa,South Korea,Spain,Sweden,Switzerland,Turkey,United Kingdom
-
US almost stands alone. Looks like the CEO of Boeing called his "friend" Trump.
Now if something does go wrong, that will have huge consequences.
https://edition.cnn.com/2019/03/13/politics/donald-trump-boeing-faa/index.html
-
Trump is reported to have lobbied Vietnam on the 737 Max so I'm not sure what arrangement he has with Boeing though if Trump is anything it is money hungry.
Brian
-
As of today the following countries has grounded the 737 MAX.
Argentina,Australia,Austria,Belgium,Brazil,Bulgaria,Cayman Islands,China,Canada,Croatia,Cyprus,Czech Republic
Denmark,Estonia,Ethiopia,Finland,France,Germany,Greece,Hungary,Iceland,India,Indonesia,Ireland,Italy,Latvia
Liechtenstein,Lithuania,Luxembourg,Malaysia,Malta,Mexico,Mongolia,Morocco,Netherlands,Norway,Oman,Poland
Portugal,Romania,Singapore,Slovakia,Slovenia,South Africa,South Korea,Spain,Sweden,Switzerland,Turkey,United Kingdom
Most of those did not separately and independently make that decision, they're simply part of the EU authority which made the decision for all of them. It's like listing all 50+ state/territory governments of the USA whenever the Federal government makes a global decision. Making the list TLDR isn't terribly helpful, unless your intent is to obscure the non-EU countries.
-
USA now also grounds the max.
Wise decision IMO.
-
https://www.reuters.com/article/us-ethiopia-airplane/u-s-grounds-737-max-jets-boeing-shares-fall-again-idUSKBN1QU15W (https://www.reuters.com/article/us-ethiopia-airplane/u-s-grounds-737-max-jets-boeing-shares-fall-again-idUSKBN1QU15W)
-
Well done!
Trump praised the airline manufacturer as a “great company” and said he hoped that Boeing will come up “very quickly” with answers to what caused the crash in Ethiopia, but “until they do the planes are grounded.”
https://www.youtube.com/watch?v=5_2Uqke5nf4 (https://www.youtube.com/watch?v=5_2Uqke5nf4)
-
Canada has now banned the 737 Max as well.
Have they? Just this morning driving to work CBC radio said the transportation minister said he won't.
-
Canada has now banned the 737 Max as well.
Have they? Just this morning driving to work CBC radio said the transportation minister said he won't.
Yes, Canada banned this morning, shortly followed by the United States
For Air Canada it's a giant PITA as the B38M represents about 25% of their narrowbody fleet; and I wouldn't want to be flying domestically as I suspect there will be a lot of cancellations and re-routing
Narrowbody fleet
70 Boeing A319/320/321
24 Boeing 737-MAX8
18 Embraer 190
What it likely means is that long-haul thin flights (like Halifax/StJohns -> London, Vancouver/Calgary -> Hawaii) really don't have much of a replacement short of them putting widebodies on the routes. From what I heard, Air Canada was one of the last 737-MAX8s to leave the UK prior to the grounding.
WestJet it's a smaller percentage
109 Boeing 737-600/700/800
13 Boeing 737-MAX8
Neither AC's nor WS's discount arms operate the B38M
-
As of today the following countries has grounded the 737 MAX.
Argentina,Australia,Austria,Belgium,Brazil,Bulgaria,Cayman Islands,China,Canada,Croatia,Cyprus,Czech Republic
Denmark,Estonia,Ethiopia,Finland,France,Germany,Greece,Hungary,Iceland,India,Indonesia,Ireland,Italy,Latvia
Liechtenstein,Lithuania,Luxembourg,Malaysia,Malta,Mexico,Mongolia,Morocco,Netherlands,Norway,Oman,Poland
Portugal,Romania,Singapore,Slovakia,Slovenia,South Africa,South Korea,Spain,Sweden,Switzerland,Turkey,United Kingdom, USA.
Most of those did not separately and independently make that decision, they're simply part of the EU authority which made the decision for all of them. It's like listing all 50+ state/territory governments of the USA whenever the Federal government makes a global decision. Making the list TLDR isn't terribly helpful, unless your intent is to obscure the non-EU countries.
I have no intent of obscure anything for anyone. STOP construct accusations!
https://nairobinews.nation.co.ke/editors-picks/us-government-warned-citizens-avoid-ethiopian-airport (https://nairobinews.nation.co.ke/editors-picks/us-government-warned-citizens-avoid-ethiopian-airport)
https://www.youtube.com/watch?v=fmOpMTZI1L0 (https://www.youtube.com/watch?v=fmOpMTZI1L0)
-
Boeing themselves have now grounded the 737 Max, making individual country decisions irrelevant.
https://www.bbc.co.uk/news/business-47562727 (https://www.bbc.co.uk/news/business-47562727)
Boeing has grounded its entire global fleet of 737 Max aircraft after investigators uncovered new evidence at the scene of the fatal Ethiopian Airlines crash.
The US plane-maker said it would suspend all 371 of the aircraft.
The Federal Aviation Administration said fresh evidence as well as newly refined satellite data prompted the decision to temporarily ban the jets.
The FAA had previously held out while many countries banned the aircraft.
The crash on Sunday in Addis Ababa killed 157 people.
It was the second fatal Max 8 disaster in five months after one crashed over Indonesia in October, claiming 189 lives.
Boeing said it "continues to have full confidence in the safety of the 737 Max".
However, it said that after consultation with the FAA and the National Transportation Safety Board - which is conducting an investigation into the Ethiopian Airlines crash - it had decided to ground the flights "out of an abundance of caution and in order to reassure the flying public of the aircraft's safety".
The FAA said: "The grounding will remain in effect pending further investigation, including examination of information from the aircraft's flight data recorders and cockpit voice recorders."
-
USA now also grounds the max.
Wise decision IMO.
I wonder if the decision to ground by the FAA is in response to data from the CVR and FDR. I have to believe that both recorders have been downloaded and a preliminary (very preliminary) review has been done and that the data is indicating a similarity with Lionair that relates to MCAS.
One thing that is new here is that numerous reports of 737 Max pilots to weirdness when autopilot is turned on but in the past we were told MCAS only activates when AP is off so perhaps there's other flight control software problems beyond MCAS or MCAS plays a role while autopilot is engaged as well. Honestly, we can put to bed the idea that this isn't a fly-by-wire AC even if it's not fly-by-wire by the conventional definition -- if the computer can wrestle control in AP or when AP is off AND the only way to prevent that is to turn systems off the idea that this is a stick flown AC is laughable.
So, in the past we were told MCAS only activated when being stick flown but the new data says the same or similar problems can also occur on AP.
Boeing is going to eat this one big time!
Brian
-
Boeing themselves have now grounded the 737 Max, making individual country decisions irrelevant.
https://www.bbc.co.uk/news/business-47562727 (https://www.bbc.co.uk/news/business-47562727)
Boeing has grounded its entire global fleet of 737 Max aircraft after investigators uncovered new evidence at the scene of the fatal Ethiopian Airlines crash.
The US plane-maker said it would suspend all 371 of the aircraft.
The Federal Aviation Administration said fresh evidence as well as newly refined satellite data prompted the decision to temporarily ban the jets.
The FAA had previously held out while many countries banned the aircraft.
The crash on Sunday in Addis Ababa killed 157 people.
It was the second fatal Max 8 disaster in five months after one crashed over Indonesia in October, claiming 189 lives.
Boeing said it "continues to have full confidence in the safety of the 737 Max".
However, it said that after consultation with the FAA and the National Transportation Safety Board - which is conducting an investigation into the Ethiopian Airlines crash - it had decided to ground the flights "out of an abundance of caution and in order to reassure the flying public of the aircraft's safety".
The FAA said: "The grounding will remain in effect pending further investigation, including examination of information from the aircraft's flight data recorders and cockpit voice recorders."
Ahh, so it looks like the investigation has already revealed information that points to a problem with the AC. I would not want to be in the Boeing PR department right now...
Brian
-
Boeing themselves have now grounded the 737 Max, making individual country decisions irrelevant.
They should have done that much earlier IMO, now it is more a joke since 3/4 of the world already took that decision for them.
-
USA now also grounds the max.
Wise decision IMO.
I wonder if the decision to ground by the FAA is in response to data from the CVR and FDR. I have to believe that both recorders have been downloaded and a preliminary (very preliminary) review has been done and that the data is indicating a similarity with Lionair that relates to MCAS.
It’s due to ADSB flight path data collected from satellites, that probably has more points that what is available to the public right now from flightaware. This is what made Canada ground them, and now the FAA, probably the pattern is the same as the indonesian plane.
As to the black boxes, ethiopian authorities wants them investigated in EU territory as they dont trust the US, however germany declined saying they dont have the software to decode them
-
New black boxes, who can read them?
-
One thing that is new here is that numerous reports of 737 Max pilots to weirdness when autopilot is turned on but in the past we were told MCAS only activates when AP is off so perhaps there's other flight control software problems beyond MCAS or MCAS plays a role while autopilot is engaged as well. Honestly, we can put to bed the idea that this isn't a fly-by-wire AC even if it's not fly-by-wire by the conventional definition -- if the computer can wrestle control in AP or when AP is off AND the only way to prevent that is to turn systems off the idea that this is a stick flown AC is laughable.
So, in the past we were told MCAS only activated when being stick flown but the new data says the same or similar problems can also occur on AP.
The 737 (everything from the -100 to MAX10) is not a fly by wire aircraft. The difference is how the control surfaces are connected to the control inputs. In the case of all 737s it's done mechanically/hydraulically, and the stick directly controls the hydraulics. That's not to say there's aren't systems like the AP or MCAS (stick shaker) that can't control the stick.
On the A320s, the input is purely a joystick into an electronic brain, aka fly-by-wire; which then actuates electro-hydraulic systems.
-
Equally interesting is the Atlas Air 767 crash two weeks ago; where they've now released some of the FDR info
...Also, about this time, the FDR data indicated that some small vertical accelerations consistent with the airplane entering turbulence. Shortly after, when the airplane’s indicated airspeed was steady about 230 knots, the engines increased to maximum thrust, and the airplane pitch increased to about 4° nose up. The airplane then pitched nose down over the next 18 seconds to about 49° in response to nose-down elevator deflection. (Editorial Note: the sentence originally read: "and then rapidly pitched nose down to about 49° in response to column input." and was later edited by the NTSB). The stall warning (stick shaker) did not activate.
...
AVHerald.com as always has much more information.
Atlas Air 3591: http://avherald.com/h?article=4c497c3c&opt=0 (http://avherald.com/h?article=4c497c3c&opt=0)
Ethiopian 302: http://avherald.com/h?article=4c534c4a&opt=0 (http://avherald.com/h?article=4c534c4a&opt=0)
Lion Air 610: http://avherald.com/h?article=4bf90724/0009&opt=0 (http://avherald.com/h?article=4bf90724/0009&opt=0)
-
Canada has now banned the 737 Max as well.
Have they? Just this morning driving to work CBC radio said the transportation minister said he won't.
Yes, Canada banned this morning, shortly followed by the United States
Followed by. Yes tell me about it. CBC was reporting all night long yesterday and this morning that the minister "does not have plans to ground the planes", quote/unquote. This guy is full of shit . Let me offer an explanation: this piece of shit minister heard that the US will do it.
-
Equally interesting is the Atlas Air 767 crash two weeks ago; where they've now released some of the FDR info
There's a video of that crash:
https://www.youtube.com/watch?v=-_YURUIvSpI (https://www.youtube.com/watch?v=-_YURUIvSpI)
-
One thing that is new here is that numerous reports of 737 Max pilots to weirdness when autopilot is turned on but in the past we were told MCAS only activates when AP is off so perhaps there's other flight control software problems beyond MCAS or MCAS plays a role while autopilot is engaged as well. Honestly, we can put to bed the idea that this isn't a fly-by-wire AC even if it's not fly-by-wire by the conventional definition -- if the computer can wrestle control in AP or when AP is off AND the only way to prevent that is to turn systems off the idea that this is a stick flown AC is laughable.
So, in the past we were told MCAS only activated when being stick flown but the new data says the same or similar problems can also occur on AP.
The 737 (everything from the -100 to MAX10) is not a fly by wire aircraft. The difference is how the control surfaces are connected to the control inputs. In the case of all 737s it's done mechanically/hydraulically, and the stick directly controls the hydraulics. That's not to say there's aren't systems like the AP or MCAS (stick shaker) that can't control the stick.
On the A320s, the input is purely a joystick into an electronic brain, aka fly-by-wire; which then actuates electro-hydraulic systems.
And once again this is a distinction without a difference. I've worked on AC (USAF) and know a thing or two about them and, yes, there is a definition related to fly-by-wire and the 737 does not meet that definition -- however, if the computer can still override the pilots inputs to the stick this distinction is largely irrelevant. The pertinent point is that a computer is controlling things and it makes little difference if the pilot has a direct connection to the control surfaces or if the computer is in between -- if the computer can wrestle control from the pilot the end effect is the same. In fact, the idea that a pilot has direct control of the control surfaces on a 737 is laughable anyway as there's a hydraulic system in between -- not like AC where the yoke directly connects to the control surfaces with cables. Look, we've been down this semantic road before and its tiring to continue the pretense that an AC like the 737 isn't controlled by computer even if a formal definition would argue it isn't. It is a sure bet that most if not all the update Boeing plans is SOFTWARE.
Brian
-
Equally interesting is the Atlas Air 767 crash two weeks ago; where they've now released some of the FDR info
There's a video of that crash:
https://www.youtube.com/watch?v=-_YURUIvSpI (https://www.youtube.com/watch?v=-_YURUIvSpI)
The thing that strikes me about this video is that there is little roll activity -- the plane just flies straight into the swamp. I also note the absence of any smoke suggesting the problem is unlikely to be engine or cargo fire related.
Brian
-
The thing that strikes me about this video is that there is little roll activity -- the plane just lies straight into the swamp. I also note the absence of any smoke suggesting the problem is unlikely to be engine or cargo fire related.
Here's some info:
https://www.youtube.com/watch?v=nJo2jGz34uM (https://www.youtube.com/watch?v=nJo2jGz34uM)
-
Man this thread has blown up into a long one, so I haven't read everything here yet.
I'm interested in this, as is the rest of the aviation and some of the engineering community I bet.
I am a instrument rated pilot.
One thing I can say, is that airline pilots rarely fly in the traditional sense anymore, because of all the automation and systems. Not good nor bad, it's just how the industry is now. The extent that airline pilots "fly" is more like babysitting a system, with some manual control often done during take-off and landings depending on the capabilities of the airport in use and systems onboard. When something goes wrong, the pilots look at each other and say "whys it doing that" instead of disengaging the autopilot (breaking the circuit breaker if it is a safety system that is not disconnected with autopilot), grabbing the controls, and fly the darn plane. I may be ignorant here not reading all the circumstances and evidence yet, but just my initial 2 cents.. carry on!
-
One thing that is new here is that numerous reports of 737 Max pilots to weirdness when autopilot is turned on but in the past we were told MCAS only activates when AP is off so perhaps there's other flight control software problems beyond MCAS or MCAS plays a role while autopilot is engaged as well. Honestly, we can put to bed the idea that this isn't a fly-by-wire AC even if it's not fly-by-wire by the conventional definition -- if the computer can wrestle control in AP or when AP is off AND the only way to prevent that is to turn systems off the idea that this is a stick flown AC is laughable.
So, in the past we were told MCAS only activated when being stick flown but the new data says the same or similar problems can also occur on AP.
The 737 (everything from the -100 to MAX10) is not a fly by wire aircraft. The difference is how the control surfaces are connected to the control inputs. In the case of all 737s it's done mechanically/hydraulically, and the stick directly controls the hydraulics. That's not to say there's aren't systems like the AP or MCAS (stick shaker) that can't control the stick.
On the A320s, the input is purely a joystick into an electronic brain, aka fly-by-wire; which then actuates electro-hydraulic systems.
And once again this is a distinction without a difference. I've worked on AC (USAF) and know a thing or two about them and, yes, there is a definition related to fly-by-wire and the 737 does not meet that definition -- however, if the computer can still override the pilots inputs to the stick this distinction is largely irrelevant. The pertinent point is that a computer is controlling things and it makes little difference if the pilot has a direct connection to the control surfaces or if the computer is in between -- if the computer can wrestle control from the pilot the end effect is the same. In fact, the idea that a pilot has direct control of the control surfaces on a 737 is laughable anyway as there's a hydraulic system in between -- not like AC where the yoke directly connects to the control surfaces with cables. Look, we've been down this semantic road before and its tiring to continue the pretense that an AC like the 737 isn't controlled by computer even if a formal definition would argue it isn't. It is a sure bet that most if not all the update Boeing plans is SOFTWARE.
Brian
Saying something is fly-by-wire when it's fly-by-hydraulic is like saying an electric water heater is the same as an gas one, just because they both accomplish the same goal. I agree that the problem likely is not in the method of transmitting force to the actuators, but that's no excuse for using a term describing that method to describe something else. If it's a software problem, call it a software or computer problem. If its a sensor problem, call it a sensor problem. Using the wrong term will get you push-back, as you've discovered multiple times in this thread already.
-
Not mentioned here, but there have been a few other similar airdata computer/autopilot plunge accidents (bad data=bad programmed response); such as
A330-200 Air France 447 crashed off the coast of Brazil
A330-300 Qantas 72 which diverted to Learmonth
-
One thing that is new here is that numerous reports of 737 Max pilots to weirdness when autopilot is turned on but in the past we were told MCAS only activates when AP is off so perhaps there's other flight control software problems beyond MCAS or MCAS plays a role while autopilot is engaged as well. Honestly, we can put to bed the idea that this isn't a fly-by-wire AC even if it's not fly-by-wire by the conventional definition -- if the computer can wrestle control in AP or when AP is off AND the only way to prevent that is to turn systems off the idea that this is a stick flown AC is laughable.
So, in the past we were told MCAS only activated when being stick flown but the new data says the same or similar problems can also occur on AP.
The 737 (everything from the -100 to MAX10) is not a fly by wire aircraft. The difference is how the control surfaces are connected to the control inputs. In the case of all 737s it's done mechanically/hydraulically, and the stick directly controls the hydraulics. That's not to say there's aren't systems like the AP or MCAS (stick shaker) that can't control the stick.
On the A320s, the input is purely a joystick into an electronic brain, aka fly-by-wire; which then actuates electro-hydraulic systems.
And once again this is a distinction without a difference. I've worked on AC (USAF) and know a thing or two about them and, yes, there is a definition related to fly-by-wire and the 737 does not meet that definition -- however, if the computer can still override the pilots inputs to the stick this distinction is largely irrelevant. The pertinent point is that a computer is controlling things and it makes little difference if the pilot has a direct connection to the control surfaces or if the computer is in between -- if the computer can wrestle control from the pilot the end effect is the same. In fact, the idea that a pilot has direct control of the control surfaces on a 737 is laughable anyway as there's a hydraulic system in between -- not like AC where the yoke directly connects to the control surfaces with cables. Look, we've been down this semantic road before and its tiring to continue the pretense that an AC like the 737 isn't controlled by computer even if a formal definition would argue it isn't. It is a sure bet that most if not all the update Boeing plans is SOFTWARE.
Brian
Saying something is fly-by-wire when it's fly-by-hydraulic is like saying an electric water heater is the same as an gas one, just because they both accomplish the same goal. I agree that the problem likely is not in the method of transmitting force to the actuators, but that's no excuse for using a term describing that method to describe something else. If it's a software problem, call it a software or computer problem. If its a sensor problem, call it a sensor problem. Using the wrong term will get you push-back, as you've discovered multiple times in this thread already.
In every post I've made on this topic I've made it clear that the technical description of fly-by-wire does not match what the 737 Max is, the point I'm making is that this technical difference is irrelevant given the fact that the computer is controlling the control surfaces. One could argue that fly-by-wire is inaccurate anyway if in fact the wire is an optical fiber!
Brian
-
So if Boeing grounded all the planes based on some new data found from the flight recorders, are we to assume there is some software glitch they discovered with their flight control system? Something in the software that is making an improper calculation/correction and perhaps even exaggerating the problem under certain conditions (like a run-away effect)? I'm sure there are millions of lines of code in there and somewhere earlier in the thread I believe someone mentioned that they "simulated" the behaviour of earlier planes in the new MAX series so that pilots would feel like they were flying an older plane they were used to.
I'm sure some of the experienced pilots in this thread can shed some light on what exactly modern sophisticated passenger jet software does and how it is supposed to aid pilots. Other than instrumentation, how much is the software flying the plane and how much is it just informing the pilot? This may boil down to a philosophical question regarding autonomous computer-controlled transportation in general and the statistical argument about safety versus human comfort level. For example, if you say had fully computer-controlled aircraft (from take off to landing) and found that the safety improved by a factor of 2x, would people still be willing to let a computer fly them, or would they rather have a human behind the wheel even knowing statistically-speaking that it would double their chance of a fatal crash? Sure, the numbers tell us something but psychologically how ready are we to allow computers to take full control?
-
Though auto-takeoff and autoland (in addition to the cruise autopilot) have actually existed for many decades, making it theoretically possible for an aircraft to have every phase of flight automated, this isn’t really done in practice.
Autopilot isn’t a single thing. It’s an umbrella term for dozens of discrete automation functions that can be used all at once, or none at all, or in any combination. So things like auto-navigation (automatic turns), auto level (maintain flight level), autothrottle (maintain speed), auto brake (on landing) etc. But tons more are automatic safeguards, like stall prevention.
In this case, they added another computer-controlled automatic adjustment to compensate for the different lift characteristics of the MAX, to make it behave like a classic 737, so that a pilot doesn’t have to be completely recertified for a different aircraft type, which would be needed if it handled differently. The problem is simply that they didn’t even mention this new system to pilots, never mind explain how to disable it when faulty sensors are causing it to make erroneous corrections, as happened with Lion Air and may have happened with Ethiopian.
Back to your question: no flight is ever under total computer control. Far from it. The pilots are coordinating the bazillions of different settings and modes, some manually, others through automation. The programming is critical (like, you must correctly enter the flight plan, so that auto nav knows when to turn). And a flight is never flown according only to pre-decided steps: air traffic control is directing them what to do, when to do it, etc. So for example, you may choose to use auto level at cruise, but you’re still in contact with air traffic control, who tell you which flight level to use, and you must enter that into the autopilot yourself, and ensure it’s in a mode that allows it to change flight level.
People mistakenly think that pilots don’t do anything. But in fact, aviation is extremely demanding, with tons of tasks that must be done without fail. And so offloading some of the workload to the autopilot makes total sense. But pilots also want to fly. They didn’t do all that training and spend years earning poverty wages as junior pilots only to then sit in the cockpit and do nothing. So often, they do many things manually that they could automate. And other things, like takeoffs and landings, are never done automated, even if the hardware and software is present. They’re there as backup systems if, for instance, a pilot is incapacitated and the copilot is also occupied with some emergency and needs to offload a task.
-
Though auto-takeoff and autoland (in addition to the cruise autopilot) have actually existed for many decades, making it theoretically possible for an aircraft to have every phase of flight automated, this isn’t really done in practice.
Autopilot isn’t a single thing. It’s an umbrella term for dozens of discrete automation functions that can be used all at once, or none at all, or in any combination. So things like auto-navigation (automatic turns), auto level (maintain flight level), autothrottle (maintain speed), auto brake (on landing) etc. But tons more are automatic safeguards, like stall prevention.
Yep, it's called FMS; Flight Management System.
Usually engaged/disengaged just after takeoff and just before landing and depending on guidance systems and weather conditions disengagement might be as low as 10's of feet above the runway.
-
Not mentioned here, but there have been a few other similar airdata computer/autopilot plunge accidents (bad data=bad programmed response); such as
A330-200 Air France 447 crashed off the coast of Brazil
A330-300 Qantas 72 which diverted to Learmonth
One of the points the proponents of Boeing AC have made relative to Airbus is that Boeing AC permitted the pilots greater control over the plane whereas Airbus went full in with the all-seeing all-controlling control system. What these latest accidents in Boeing planes suggests is that Boeing doesn't appear to have a leg to stand on in this respect -- at least not any more. It's too soon to say of the Amazon plane that crashed last week was also due to the computer doing something the crew either didn't comprehend or couldn't fight. If the 767 crash winds up being a similar computer control issue then Boeing could be toast and i'm 100% serious about that as far as commercial aviation is concerned. The last 20-30 years has seen software come to dominate the tech world where hardware used to, but sometimes the software types don't know as much as they think they do or they think pilots are so stupid they need to be kept on a leash.
Brian
-
https://www.youtube.com/watch?v=3jGNn2T_gyU (https://www.youtube.com/watch?v=3jGNn2T_gyU)
-
One of the points the proponents of Boeing AC have made relative to Airbus is that Boeing AC permitted the pilots greater control over the plane whereas Airbus went full in with the all-seeing all-controlling control system. What these latest accidents in Boeing planes suggests is that Boeing doesn't appear to have a leg to stand on in this respect -- at least not any more. It's too soon to say of the Amazon plane that crashed last week was also due to the computer doing something the crew either didn't comprehend or couldn't fight. If the 767 crash winds up being a similar computer control issue then Boeing could be toast and i'm 100% serious about that as far as commercial aviation is concerned. The last 20-30 years has seen software come to dominate the tech world where hardware used to, but sometimes the software types don't know as much as they think they do or they think pilots are so stupid they need to be kept on a leash.
A classic example of this is the Therac-25 incidents. https://web.stanford.edu/class/cs240/old/sp2014/readings/therac-25.pdf
-
The last 20-30 years has seen software come to dominate the tech world where hardware used to, but sometimes the software types don't know as much as they think they do or they think pilots are so stupid they need to be kept on a leash.
This is nonsense. The "software guys" do not make the use cases, requirements and safety concerned issues.
There should be a product owner, (sub)system architects and system engineers that can translate the use cases to requirements and that should involve safety features including redundant systems and fallback scenario's.
Then there should be an elaborate testing phase where all systems and software routines are rigurously tested, esp the safety critical ones with high impact, they should be continuously tested in simulators.
For a modern airplane I can imagine this would take years. Why do you think the software update took so long? It needs to be restested the whole shabang.
In any good business this is in place esp. where safety and reliability is a major issue.
BTW many accidents in the past where hardware related, a bolt that was made from the wrong steel and broke off, a sensor that was cluttered, so to say software is worse than hardware.... they both can be cause for an accident.
-
Boeing Statement On 737 MAX Software Enhancement
http://aero-news.net/index.cfm?do=main.textpost&ID=78526990-A846-4929-8D11-9D3C0FDD9DE3 (http://aero-news.net/index.cfm?do=main.textpost&ID=78526990-A846-4929-8D11-9D3C0FDD9DE3)
For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.
[...]
Boeing’s 737 MAX Flight Crew Operations Manual (FCOM) already outlines an existing procedure to safely handle the unlikely event of erroneous data coming from an angle of attack (AOA) sensor. The pilot will always be able to override the flight control law using electric trim or manual trim. In addition, it can be controlled through the use of the existing runaway stabilizer procedure as reinforced in the Operations Manual Bulletin (OMB) issued on Nov. 6, 2018
Emergency Airworthiness Directive (AD) 2018-23-51 is sent to owners and operators of The Boeing Company Model 737-8 and -9 airplanes.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument)
This emergency AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer. This condition, if not addressed, could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.
[...]
Runaway Stabilizer
Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required. If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT. If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.
Note: The 737-8/-9 uses a Flight Control Computer command of pitch trim to improve longitudinal handling characteristics. In the event of erroneous Angle of Attack (AOA) input, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds.
In the event an uncommanded nose down stabilizer trim is experienced on the 737-8/-9, in conjunction with one or more of the indications or effects listed below, do the existing AFM Runaway Stabilizer procedure above, ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.
An erroneous AOA input can cause some or all of the following indications and effects:
• Continuous or intermittent stick shaker on the affected side only.
• Minimum speed bar (red and black) on the affected side only.
• Increasing nose down control forces.
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
• Autopilot may disengage.
• Inability to engage autopilot.
Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT.
-
Not mentioned here, but there have been a few other similar airdata computer/autopilot plunge accidents (bad data=bad programmed response); such as
A330-200 Air France 447 crashed off the coast of Brazil
I'm not sure you can blame that on the computer, the computer switched to alternate law when it didn't believe the sensor input,
leaving the controls to the pilots with the task of not crashing a perfectly functional plane flying at 38000 feet
-
Not mentioned here, but there have been a few other similar airdata computer/autopilot plunge accidents (bad data=bad programmed response); such as
A330-200 Air France 447 crashed off the coast of Brazil
I'm not sure you can blame that on the computer, the computer switched to alternate law when it didn't believe the sensor input,
leaving the controls to the pilots with the task of not crashing a perfectly functional plane flying at 38000 feet
And the pilots then did the same dumb thing that the auto-pilot appears to have done on the 737-MAX aircraft, pushed the nose down to gain speed....
-
And the pilots then did the same dumb thing that the auto-pilot appears to have done on the 737-MAX aircraft, pushed the nose down to gain speed....
Had to check, because that's not what I remembered:
In fact, they did the exact opposite. Had they put the nose down, instead of up, the plane would (probably) not have crashed.
From wikipedia (https://en.wikipedia.org/wiki/Air_France_Flight_447):
From there until the end of the flight, the angle of attack never dropped below 35 degrees.
Having flown with Ethiopian airlines twice a month for several years, I was quite shocked by this disaster.
-
And the pilots then did the same dumb thing that the auto-pilot appears to have done on the 737-MAX aircraft, pushed the nose down to gain speed....
Had to check, because that's not what I remembered:
In fact, they did the exact opposite. Had they put the nose down, instead of up, the plane would (probably) not have crashed.
From wikipedia (https://en.wikipedia.org/wiki/Air_France_Flight_447):
From there until the end of the flight, the angle of attack never dropped below 35 degrees.
Having flown with Ethiopian airlines twice a month for several years, I was quite shocked by this disaster.
Sorry, I got it backwards, but it was still incorrect airdata info that led to (in this case) pilots doing the wrong thing. I do remember being told "If you lost all instruments - 75% power, keep it level - and it will fly"
-
And the pilots then did the same dumb thing that the auto-pilot appears to have done on the 737-MAX aircraft, pushed the nose down to gain speed....
NO NO! That't the PROBLEM! They SHOULD have pushed the stick forward, to exit the stall and get flying. But, at least ONE pilot held the stick full back until they hit the water! The other pilot was pushing full forward, which was what was needed to break out of the stall. But, because these sticks are not coupled and do not have any force feedback, the pilots did not know what the other one was doing.
Something that may have confused them is the Airbus suppresses the stall warning below 70 knots airspeed, so you don't have the horn blaring during landing.
But, this caused the horn to start blaring each time they began to escape from the stall. Somehow the one pilot believed that by pulling back on his stick and keeping the horn from sounding, he was ESCAPING from the stall. Total lack of understanding the systems.
Jon
-
Total lack of understanding the systems.
Or are the systems designed ambiguous ?
-
Emergency Airworthiness Directive (AD) 2018-23-51 is sent to owners and operators of The Boeing Company Model 737-8 and -9 airplanes.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument)
This emergency AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer. This condition, if not addressed, could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.
[...]
Runaway Stabilizer
Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required. If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT. If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.
Note: The 737-8/-9 uses a Flight Control Computer command of pitch trim to improve longitudinal handling characteristics. In the event of erroneous Angle of Attack (AOA) input, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds.
In the event an uncommanded nose down stabilizer trim is experienced on the 737-8/-9, in conjunction with one or more of the indications or effects listed below, do the existing AFM Runaway Stabilizer procedure above, ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.
An erroneous AOA input can cause some or all of the following indications and effects:
• Continuous or intermittent stick shaker on the affected side only.
• Minimum speed bar (red and black) on the affected side only.
• Increasing nose down control forces.
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
• Autopilot may disengage.
• Inability to engage autopilot.
Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT.
That's quite the software "workaround" for when the aircraft hardware (i.e. the angle-of-attack sensors, etc.) goes whacko. I wouldn't want to be reading those instructions for the first time while the plane is trying its damndest to dive nose-first with "possible impact with terrain".
I'd be thinking that the recovery maneuvers as described above would need to be a simulator-based exercise repeated until it was thoroughly drilled in. No time for "is the aircraft doing that thing with the bad AOA sensor or is something else wrong?" discussions in the cockpit.
-
Emergency Airworthiness Directive (AD) 2018-23-51 is sent to owners and operators of The Boeing Company Model 737-8 and -9 airplanes.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument)
This emergency AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer. This condition, if not addressed, could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.
[...]
Runaway Stabilizer
Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required. If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT. If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.
Note: The 737-8/-9 uses a Flight Control Computer command of pitch trim to improve longitudinal handling characteristics. In the event of erroneous Angle of Attack (AOA) input, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds.
In the event an uncommanded nose down stabilizer trim is experienced on the 737-8/-9, in conjunction with one or more of the indications or effects listed below, do the existing AFM Runaway Stabilizer procedure above, ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.
An erroneous AOA input can cause some or all of the following indications and effects:
• Continuous or intermittent stick shaker on the affected side only.
• Minimum speed bar (red and black) on the affected side only.
• Increasing nose down control forces.
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
• Autopilot may disengage.
• Inability to engage autopilot.
Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT.
That's quite the software "workaround" for when the aircraft hardware (i.e. the angle-of-attack sensors, etc.) goes whacko. I wouldn't want to be reading those instructions for the first time while the plane is trying its damndest to dive nose-first with "possible impact with terrain".
I'd be thinking that the recovery maneuvers as described above would need to be a simulator-based exercise repeated until it was thoroughly drilled in. No time for "is the aircraft doing that thing with the bad AOA sensor or is something else wrong?" discussions in the cockpit.
It's not a software workaround, it's a procedural workaround. The procedure itself is actually pretty simple (STAB TRIM CUTOUT switches to CUTOUT, adjust trim by hand wheel). Most of the above is explanation, not procedure.
The software workaround is what Boeing is currently developing.
Any affected pilot reading those instructions for the first time during an event has failed their duty as a pilot, and their employer has failed at training. Stuff like this is not optional reading material.
-
Emergency Airworthiness Directive (AD) 2018-23-51 is sent to owners and operators of The Boeing Company Model 737-8 and -9 airplanes.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83EC7F95F3E5BFBD8625833E0070A070?OpenDocument)
This emergency AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer. This condition, if not addressed, could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.
[...]
Runaway Stabilizer
Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required. If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT. If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.
Note: The 737-8/-9 uses a Flight Control Computer command of pitch trim to improve longitudinal handling characteristics. In the event of erroneous Angle of Attack (AOA) input, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds.
In the event an uncommanded nose down stabilizer trim is experienced on the 737-8/-9, in conjunction with one or more of the indications or effects listed below, do the existing AFM Runaway Stabilizer procedure above, ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.
An erroneous AOA input can cause some or all of the following indications and effects:
• Continuous or intermittent stick shaker on the affected side only.
• Minimum speed bar (red and black) on the affected side only.
• Increasing nose down control forces.
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
• Autopilot may disengage.
• Inability to engage autopilot.
Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT.
That's quite the software "workaround" for when the aircraft hardware (i.e. the angle-of-attack sensors, etc.) goes whacko. I wouldn't want to be reading those instructions for the first time while the plane is trying its damndest to dive nose-first with "possible impact with terrain".
I'd be thinking that the recovery maneuvers as described above would need to be a simulator-based exercise repeated until it was thoroughly drilled in. No time for "is the aircraft doing that thing with the bad AOA sensor or is something else wrong?" discussions in the cockpit.
I read somewhere that US airlines have a custom software for the Max that permanently displays the AOA for MCAS on the main display, I guess so
the pilots can instantly see if the value makes sense
-
It's not a software workaround, it's a procedural workaround. The procedure itself is actually pretty simple (STAB TRIM CUTOUT switches to CUTOUT, adjust trim by hand wheel). Most of the above is explanation, not procedure.
The software workaround is what Boeing is currently developing.
Any affected pilot reading those instructions for the first time during an event has failed their duty as a pilot, and their employer has failed at training. Stuff like this is not optional reading material.
I suppose the type of "workaround" is a semantic argument, but I'd say that if mission-critical system software such as this can't correctly handle faulty inputs like a defective AOA sensor, and instead needs timely and critical human intervention to avoid a disaster, then there's something wrong with the software, and the efforts needed to do the job that software should be doing constitute a workaround.
I would think that what Boeing is currently developing would be software that does what it should, and not simply "workaround" what it has already written.
-
A software workaround is when your software is changed to handle a failure in some other system.
So when hardware fails, whatever the software does to compensate is, by definition, a workaround -- something designed to work as well as possible until the failing system can be repaired. There are many other workarounds designed into avionics software, as there are many systems that have the potential to fail. This is one that just wasn't done right the first time around. And got through testing and review.
-
News reports suggest that part of the reason they were able to tie the two crashes together and point towards both crashes having a similar/same cause and before they had the FDR or CVR was the position of the horizontal stabilizer jack screw. If the plane was forced down by MCAS or similar the jack screw would be wound up towards one end of travel -- the end forcing the plane down. That, on top of the refined GPS altitude data pointing to a bucking bronco ride into the ground is pretty clear evidence that Lionair and this crash have a common cause.
The French now have the recorders and hopefully we'll get a preliminary readout on them tomorrow or soon and I would be very interested to know what the AOA, altitude and airspeed indications were and what differences, if any, one side had versus the other.
Brian
-
That, on top of the refined GPS altitude data pointing to a bucking bronco ride into the ground is pretty clear evidence that Lionair and this crash have a common cause.
That is absolutely incorrect.
At this point, you cannot say they have a common cause. What you can say is that they have an apparently similar symptom.
This is one of the specific areas of objectivity of crash analysts that cannot be understated ... and it is why only the Media are making such a big noise with hypotheses. You can never allow previous incidents to influence a current investigation or you could end up with "scenario fulfillment" instead of an accurate, unbiased report on what actually happened.
"Feel good" answers don't stop planes falling out of the sky in the future. Only ones derived from meticulous scrutiny by objective, trained staff following a rigorous process will.
This is the reason why I will not speculate on events such as these.
-
The similar time-constant apparently correlates to the anti-stall automation at work.
Even to a layman, Boeing's MCAS implementation is shit, even if it's not a factor in the ET 302 crash.
I can't see why we defend the mighty Boeing and blame the pilots for not executing some manual sequence from hell.
People say Boeing's product-development cycle cannot move this fast (to compete with Airbus) and continue to make safe aircraft. Using undocumented automation to cover up a handling problem, then sneak it through FAA approvals is terrible. There is huge money at stake here, Boeing's stock losing $28B in market cap and there are $600B of orders in the books.
Kudos to Ethiopian Airlines for not giving the black boxes over to US authorities, and instead having France's BEA do the investigation. I have no confidence in the FAA after insisting the aircraft is airworthy despite the rest of the world grounding the aircraft, and how MCAS made it through certification in the first place.
-
That, on top of the refined GPS altitude data pointing to a bucking bronco ride into the ground is pretty clear evidence that Lionair and this crash have a common cause.
That is absolutely incorrect.
At this point, you cannot say they have a common cause. What you can say is that they have an apparently similar symptom.
This is one of the specific areas of objectivity of crash analysts that cannot be understated ... and it is why only the Media are making such a big noise with hypotheses. You can never allow previous incidents to influence a current investigation or you could end up with "scenario fulfillment" instead of an accurate, unbiased report on what actually happened.
"Feel good" answers don't stop planes falling out of the sky in the future. Only ones derived from meticulous scrutiny by objective, trained staff following a rigorous process will.
This is the reason why I will not speculate on events such as these.
Oh please, while there is more to learn from the FDR and CVR and it is possible the cause will point elsewhere, the idea that the forensic data from the crashed plane and the data from the broadcast GPS data are meaningless is, well, laughable. The fact is, the results of those aforementioned two datapoints are that dozens of airlines and aviation agencies including the FAA grounded the 737 Max, before the data from the FDR and CVR were even downloaded, and even the manufacturer, Boeing, was compelled to call for the grounding, prior to the analysis of the CVR and FDR, makes it crystal clear that the consensus view of the experts is that the similarities are sufficient to call for grounding. And, while it is possible that analysis of the recorders will clear this 737 Max from a MCAS or similar automation problem, the data they have already was enough to make a call that will cost billions to numerous airline and quite possibly many billions for Boeing. Not to mention the unavoidable impact that this grounding will have on millions of airline passengers and quite possibly for months or longer. Perhaps try and be a bit less sanctimonious!
Brian
-
Really?
I never said that the fallout for Boeing wouldn't be significant - no matter what the outcome. So don't try throwing that in my face.
All I AM saying is that ANYBODY who has "determined" the cause of this accident at this point in time is not basing it on all the facts.
You MAY be right - and if it does turn out that you are, that still does not give you any right to be sanctimonious about your guessing at this stage.
Just pile on with the Media circus. You'll enjoy their company.
I'll wait.
-
But Brumby, the data we already have is very telling, isn't it?
-
I agree with Brumby, if you do not have all the information it becomes speculation.
The grounding of the plane AFAIK is foremost taken because it is a new plane AND two brand new planes crashed within a half year.
-
The grounding of the plane AFAIK is foremost taken because it is a new plane AND two brand new planes crashed within a half year.
... apparently in the same way and for the same reason. No?
-
But Brumby, the data we already have is very telling, isn't it?
It does lend itself to the conclusions the Media is jumping to with great haste. As I said, it may be that those conclusions could be close to the truth - but the information available is by no means sufficient to start drawing definitive conclusions at this time.
... apparently in the same way and for the same reason. No?
Even that is a little too far for my liking - but it does acknowledge an element of uncertainty, which is appropriate.
-
That, on top of the refined GPS altitude data pointing to a bucking bronco ride into the ground is pretty clear evidence that Lionair and this crash have a common cause.
That is absolutely incorrect.
At this point, you cannot say they have a common cause. What you can say is that they have an apparently similar symptom.
This is one of the specific areas of objectivity of crash analysts that cannot be understated ... and it is why only the Media are making such a big noise with hypotheses. You can never allow previous incidents to influence a current investigation or you could end up with "scenario fulfillment" instead of an accurate, unbiased report on what actually happened.
In one of the "Air Crash Investigation" episodes one of the investigators said they internationally do not watch any kind of news
before examining the crash site
-
The grounding of the plane AFAIK is foremost taken because it is a new plane AND two brand new planes crashed within a half year.
... apparently in the same way and for the same reason. No?
You can not talke about "The same reason" while the cause is not 100% determined and investigation is not completed IMO.
I would go as far as that two new planes crash within a limited timeframe without obvious external cause.
(If there was a second plane involved that crashed into the plane or that there was extreme weather like a tornado etc. that would IMO be an external cause)
-
That, on top of the refined GPS altitude data pointing to a bucking bronco ride into the ground is pretty clear evidence that Lionair and this crash have a common cause.
That is absolutely incorrect.
At this point, you cannot say they have a common cause. What you can say is that they have an apparently similar symptom.
This is one of the specific areas of objectivity of crash analysts that cannot be understated ... and it is why only the Media are making such a big noise with hypotheses. You can never allow previous incidents to influence a current investigation or you could end up with "scenario fulfillment" instead of an accurate, unbiased report on what actually happened.
In one of the "Air Crash Investigation" episodes one of the investigators said they internationally do not watch any kind of news
before examining the crash site
Yep.
And also, there have been cases where crash investigators announced the cause prematurely, and it turned out that their initial suspicion was wrong.
-
Kudos to Ethiopian Airlines for not giving the black boxes over to US authorities, and instead having France's BEA do the investigation. I have no confidence in the FAA after insisting the aircraft is airworthy despite the rest of the world grounding the aircraft, and how MCAS made it through certification in the first place.
Your mistrust is misplaced, then, because the FAA isn't responsible for crash investigations at all. Black boxes are sent to the NTSB, a completely different arm of government that is independent from the FAA. (It doesn't make rules, it produces crash reports and recommendations, which regulatory agencies like the FAA, as well as manufacturers, can choose to follow, or not.)
-
Kudos to Ethiopian Airlines for not giving the black boxes over to US authorities, and instead having France's BEA do the investigation. I have no confidence in the FAA after insisting the aircraft is airworthy despite the rest of the world grounding the aircraft, and how MCAS made it through certification in the first place.
Your mistrust is misplaced, then, because the FAA isn't responsible for crash investigations at all. Black boxes are sent to the NTSB, a completely different arm of government that is independent from the FAA. (It doesn't make rules, it produces crash reports and recommendations, which regulatory agencies like the FAA, as well as manufacturers, can choose to follow, or not.)
Correct.
Grew up around airline and aviation people. The NTSB is world-class. Their labs and investigative abilities set the standard
-
Correct.
Grew up around airline and aviation people. The NTSB is world-class. Their labs and investigative abilities set the standard
Agreed, but Nasa is also world-class and political/administrative pressures made the Columbia accident happen.
So given this is not a cessna or learjet accident investigation, and given the interests are extremely high due to uncalculable economic losses a bit of caution regarding who investigates this is understandable
Also, the plane was configured to crash dive, https://www.bloomberg.com/news/articles/2019-03-15/piece-found-in-crash-wreckage-said-to-show-jet-was-set-to-dive (https://www.bloomberg.com/news/articles/2019-03-15/piece-found-in-crash-wreckage-said-to-show-jet-was-set-to-dive)
-
Grew up around airline and aviation people. The NTSB is world-class. Their labs and investigative abilities set the standard
All NTSB investigations go like this: if the pilot died in the accident, it was a pilot error ~ 100% of the times, if he's alive, 50/50 chance of he being the culprit. Just watch the "Mayday" series and do the math.
Another example: we've been flying in 747 Jumbos with faulty cargo door lock mechanisms for decades... and they knew that. It was the father of a victim who had to demonstrate that, because the NTSB was hiding the truth:
https://en.wikipedia.org/wiki/United_Airlines_Flight_811#Personal_investigation_and_later_developments
I for one am glad the ET 302 black box wasn't sent to the USA, it's not a good thing when the judge is a part.
-
https://www.sapromo.com/737-max-crash-a-jackscrew-screwed-up/47577 (https://www.sapromo.com/737-max-crash-a-jackscrew-screwed-up/47577)
MyBroadband.co.za reports that the US’s Federal Aviation Administration chief Daniel Elwell earlier this week cited unspecified evidence found at the crash scene as part of the justification for the agency to reverse course and temporarily halt flights of Boeing’s largest selling aircraft. Up until then, American regulators had held off as nation after nation had grounded the plane, Boeing’s best-selling jet model.
The piece of evidence was a so-called jackscrew, used to set the trim that raises and lowers the plane’s nose, according to the person, who requested anonymity to discuss the inquiry.
A preliminary review of the device and how it was configured at the time of the crash indicated that it was set to push down the nose, according to the person, who wasn’t authorized to speak publicly about the investigation.
The jackscrew, combined with a newly obtained satellite flight track of the plane, convinced the FAA that there were similarities to the Oct. 29 crash of the same Max model off the coast of Indonesia. In the earlier accident, a safety feature on the Boeing aircraft was repeatedly trying to put the plane into a dive as a result of a malfunction.
All 157 people aboard Ethiopian Airlines Flight 302 died early Sunday shortly after the plane took off. The pilot reported an unspecified problem and was trying to return to the airport. The plane crashed near Addis Ababa, Ethiopia’s capital. The plane’s crash-proof recorders have been sent to France to be analyzed.
The discovery of the jackscrew was earlier reported by NBC News.
One plus one...
-
Kudos to Ethiopian Airlines for not giving the black boxes over to US authorities, and instead having France's BEA do the investigation. I have no confidence in the FAA after insisting the aircraft is airworthy despite the rest of the world grounding the aircraft, and how MCAS made it through certification in the first place.
Your mistrust is misplaced, then, because the FAA isn't responsible for crash investigations at all. Black boxes are sent to the NTSB, a completely different arm of government that is independent from the FAA. (It doesn't make rules, it produces crash reports and recommendations, which regulatory agencies like the FAA, as well as manufacturers, can choose to follow, or not.)
I'm not clear then on what US agency Ethiopian Airlines is blowing off, by getting France's BEA to do the crash investigation.
The NTSB can make recommendations to the FAA, who may or may not choose to adopt them.
Who is driving the software update to the MCAS? It should not be Boeing, as their processes already failed implementing it, and not the FAA for wrongly certifying it.
As an outcome of the Lion Air crash investigation, I assume some agency recommended MCAS changes- which were not rolled out and of course they would make Boeing liable.
-
As an outcome of the Lion Air crash investigation, I assume some agency recommended MCAS changes- which were not rolled out and of course they would make Boeing liable.
What outcome? The accident happened last October, one black box was found in November and the other one in January. Plus both the FAA and NTSB mostly stopped working for a month because Trump shut down the government. NTSB is thorough and professional and doesn't jump to conclusions like most of us, but the price is time. Expect their report and recommendations in a year or so.
It'll show up here: https://www.ntsb.gov/investigations/AccidentReports/Pages/aviation.aspx (https://www.ntsb.gov/investigations/AccidentReports/Pages/aviation.aspx)
All we have so far is some data releases. And we've yet to hear what the cockpit recorder said at all.
The FAA, on the other hand, can choose to react much more quickly with Airworthiness Directives, based on events or on recommendations from aircraft manufacturers.
As for the software process, I already mentioned that earlier in the thread. It's not quick, even if you want it to be, testing is required, and the FAA does have to certify it. A few months is really fast turnaround.
-
Really?
I never said that the fallout for Boeing wouldn't be significant - no matter what the outcome. So don't try throwing that in my face.
All I AM saying is that ANYBODY who has "determined" the cause of this accident at this point in time is not basing it on all the facts.
You MAY be right - and if it does turn out that you are, that still does not give you any right to be sanctimonious about your guessing at this stage.
Just pile on with the Media circus. You'll enjoy their company.
I'll wait.
Again with the sanctimonious nonsense -- at no time did I declare the the accident was definitely this that or anything else -- you really should pull your head out of you anally retentive a$$!
The investigators, not me, have reviewed the crash scene and in combination with the broadcast GPS data have determined the crash is sufficiently similar to the Lionair crash that it warranted grounding the 737 Max. IT WAS NOT I THAT DID THAT DIP SH!T!
Brian
-
NY Times https://www.nytimes.com/2019/03/15/business/boeing-ethiopian-crash.html (https://www.nytimes.com/2019/03/15/business/boeing-ethiopian-crash.html)
-
Really?
I never said that the fallout for Boeing wouldn't be significant - no matter what the outcome. So don't try throwing that in my face.
All I AM saying is that ANYBODY who has "determined" the cause of this accident at this point in time is not basing it on all the facts.
You MAY be right - and if it does turn out that you are, that still does not give you any right to be sanctimonious about your guessing at this stage.
Just pile on with the Media circus. You'll enjoy their company.
I'll wait.
Again with the sanctimonious nonsense -- at no time did I declare the the accident was definitely this that or anything else -- you really should pull your head out of you anally retentive a$$!
The investigators, not me, have reviewed the crash scene and in combination with the broadcast GPS data have determined the crash is sufficiently similar to the Lionair crash that it warranted grounding the 737 Max. IT WAS NOT I THAT DID THAT DIP SH!T!
Brian
Calm down.
-
NY Times https://www.nytimes.com/2019/03/15/business/boeing-ethiopian-crash.html (https://www.nytimes.com/2019/03/15/business/boeing-ethiopian-crash.html)
Ethiopian 737-8 Max UPDATE:
https://www.youtube.com/watch?v=AgkmJ1U2M_Q (https://www.youtube.com/watch?v=AgkmJ1U2M_Q)
-
Raptor1956:
Just wanted to say that I came to this thread, seemingly only the other day. I had read some of the recent revelations about the MCAS and the trim/elevator and the elevation graph, and I found this paints one very clear picture of what likely happened in both of these crashes.
So when I saw this megathread, I was curious to see what the EEV hive mind thought, and I read more or less every single post from the beginning, seemingly for the first time. Curiously, though, I found I had thanked one of your earlier posts, lol. So I had visited this thread, at least once, before. And I recognized your early posts to be among the most rational and logical and comprehensive... without any innate bias. And as it turns out, I would say that hindsight will more than likely show that you were the right horse to bet on.
I just wanted you to know your input to this thread has been appreciated by me and surely by others. I hope you don't get caught up in semantic BS from latecomers to the thread. It is obvious from the thread history that you are not making assumptions at any stage in the thread. Even prior to the more recent relevations, your thought process and conjecture was unimpeachable and insightful, IMO, as a non-pilot.
-
In one of the "Air Crash Investigation" episodes one of the investigators said they internationally do not watch any kind of news before examining the crash site
Yes the fake news media would pollute any investigation.
Boing says MCAS soft fix in coming weeks.
https://www.youtube.com/watch?v=VRx8BBQyX10 (https://www.youtube.com/watch?v=VRx8BBQyX10)
-
But, because these sticks are not coupled and do not have any force feedback, the pilots did not know what the other one was doing.
This is something that has always struck me as an absolutely stupid design. If the plane has two sticks, they should absolutely be mechanically linked together, or only one set of controls should be active at a time, with a very obvious indication of which is active. I never liked the sidestick arrangement anyway, it just looks wrong, and seems like it would be awkward.
-
In one of the "Air Crash Investigation" episodes one of the investigators said they internationally do not watch any kind of news before examining the crash site
Yes the fake news media would pollute any investigation.
Ordinary trials in the UK have been thrown out because just 1 member of the jury decided to go detectiving for themselves rather than rely solely on the evidence presented in court.
-
From the video at #376:
"[...] The software fix is going to require this flight control system to rely on data from TWO sensors, it previously was only dependent on one [...]"
Really? The MCAS is reading only one sensor? That seems unbelievable to me. The engineers at Boeing no more no less, should have known better.
-
safty critical with one sensor? ouch! idealy you want 3 so you know who to trust.
-
safty critical with one sensor? ouch! idealy you want 3 so you know who to trust.
Even the accelerator pedal of my 1998 ford focus has three separate potentiometers!
Is this (in bold, below) a weasel-ish way of saying "from now on we're going to read the second AoA sensor too"?
Boeing Statement On 737 MAX Software Enhancement
http://aero-news.net/index.cfm?do=main.textpost&ID=78526990-A846-4929-8D11-9D3C0FDD9DE3 (http://aero-news.net/index.cfm?do=main.textpost&ID=78526990-A846-4929-8D11-9D3C0FDD9DE3)
For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.
[...]
-
From the video at #376:
"[...] The software fix is going to require this flight control system to rely on data from TWO sensors, it previously was only dependent on one [...]"
Really? The MCAS is reading only one sensor? That seems unbelievable to me. The engineers at Boeing no more no less, should have known better.
I think the idea will be to cross-check the two sensors for agreement, if they disagree then disable MCAS and issue a warning to the pilots.
While the engineers at Boeing should (and probably do) know better, they are overruled by finance and marketing these days.
-
I think the idea will be to cross-check the two sensors for agreement, if they disagree then disable MCAS and issue a warning to the pilots.
From reply #339:
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
AoA DISAGREE is (was?) an option! |O
But then, the second AoA sensor what for was there? For decoration?
-
I think the idea will be to cross-check the two sensors for agreement, if they disagree then disable MCAS and issue a warning to the pilots.
From reply #339:
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
AoA DISAGREE is (was?) an option! |O
But then, the second AoA what for was there? For decoration?
The second sensor is redundant, I think the sensors are fed to each seat, similar to how other controls such as altimeter. I.e. captain seat gets sensor input from LH sensors, FO seat gets info from RH sensors. The normal CRM would have the pilots determine the faulty sensor and ignore it. Unfortunately CRM is often lacking in upset situations. In this case, if they don't quickly identify the need to disable electric trim it is too late.
The AoA DISAGREE is an option few airlines have taken. It's up to the pilots to see it then disable electric trim (which also prevents MCAS moving the stabilizer).
I think the MCAS can currently only take one AoA or the other, so the fix would be to use both, or at least use the AoA DISAGREE signal to automatically disable MCAS, presumably there needs to be another alert to indicate MCAS Inoperative.
I'm afraid to say it's a set of bodges to cater for the original decision to add bigger engines, AND retain 737 flight characteristics so that minimal type conversion is required for the pilots.
Unfortunately, I see the same trend in other industries. Marketing, finance are allowed to override proper engineering. The question is always "how much will it cost?", and not "is the quality right?"
-
^ I don't get how this is even a cost issue. It seems much more like an oversight.
-
^ I don't get how this is even a cost issue. It seems much more like an oversight.
Because the 737 MAX grandfathers certification and type training from the 737 Classic. If Boeing change the design significantly, it needs a whole new certification - expensive and time consuming. If the flight characteristics change, it means new type training for the pilots, so operators need to be spend money on training, and the pilots need to get type certificate.
Boeing wanted to get a plane into production quickly, because Airbus was outselling them by a wide margin.
By telling regulators and operators that "the MAX can be treated the same as the classic", Boeing took a big shortcut compared to designing a new airframe. It seems that gamble created a major flaw.
-
It's a Boeing design error and the S/W patch allowing "the option" of using two sensors stinks of cover-up. AOA DISAGREE alert indicator is also an "option"?! :palm:
Using two sensors is still shitty because you have now doubled the probability of MCAS failure due to a sensor failure.
Multiple sensors iced up for the AF447 disaster. Would MCAS register a discrepancy with two sensors reading similar yet both are out to lunch?
I'll repeat the old adage "with two clocks you can never know the correct time". This MCAS system is never going to be stellar, even adding a third (sensor) opinion because the other pair can malfunction. It's just getting a slightly lower probability of failure, this is all Boeing can accomplish. Unless there was a gross S/W bug that is being fixed too.
In other industries with safety-critical design, you do fault-tree analysis and FMEDA to ensure you have coverage of a sensor problem, among other scenarios.
Clearly, Boeing bungled this and is showing a repeat bungle with their hasty "software fix" that cannot meet basic functional safety requirements even after piling on the algorithm smartness.
I've seen this before - a bad design safety-critical system is out there, sold in numbers and a corporation has a massive panic to fix it ASAP without changing any hardware.
Adding complex S/W algorithms (which can never be proven correct) is very dangerous.
Then I read this: (http://www.b737.org.uk/mcas.htm)
"MCAS is implemented within the two Flight Control Computers (FCCs). The Left FCC uses the Left AOA sensor for MCAS and the Right FCC uses the Right AOA sensor for MCAS. Only one FCC operates at a time to provide MCAS commands. With electrical power to the FCCs maintained, the unit that provides MCAS changes between flights. In this manner, the AOA sensor that is used for MCAS changes with each flight."
How do you come up with something so stupid?
-
I assumed that for a safety critical system you measure everything with 3 sensors, should one fail you can identify it is the failed one as two measurements still agree and you flaf the faulty sensor.
-
On the horizon i can see a large number of relatives preparing to sue Boing.
Boeing have been working on a software modification to MCAS since the Lion Air accident. Unfortunately although originally due for release in January it has still not been released due to both engineering challenges and differences of opinion among some federal and company safety experts over how extensive the changes should be. Apparently there have been discussions about potentially adding enhanced pilot training and possibly mandatory cockpit alerts to the package. There also has been consideration of more-sweeping design changes that would prevent faulty signals from a single sensor from touching off the automated stall-prevention system.
-
https://www.youtube.com/watch?v=RyeqeqSNSgQ (https://www.youtube.com/watch?v=RyeqeqSNSgQ)
Somebody remind me why MCAS is even needed?
This 737 max 8 is presumably empty, but none the less, wow an impressive climb.
ET302 took off like a bat out of hell, hard vertical climb for the first few seconds after takeoff so I wonder if a sensor was not working right from the start.
-
Somebody remind me why MCAS is even needed?
This 737 max 8 is presumably empty, but none the less, wow an impressive climb.
ET302 took off like a bat out of hell, hard vertical climb for the first few seconds after takeoff so I wonder if a sensor was not working right from the start.
The angle of attack sensors don't measure the angle with the ground or horizon, rather they measure the relative angle of the airflow to the center line of the aircraft. So if the aircraft is moving fast enough and has a high enough thrust to weight ratio it can keep on accelerating even in a steep climb. If the airspeed is increasing and the climb angle stays constant the angle of attack will actually decrease.
None the less I bet the factory pilots rehearse that manoeuvre and probably disabled MCAS. They likely also had in mind the Airbus 320 Demo flight crash where the pilots where in inadvertently fighting HAL 9000.
https://www.youtube.com/watch?v=I9gELPxPG8Q (https://www.youtube.com/watch?v=I9gELPxPG8Q)
-
On the horizon i can see a large number of relatives preparing to sue Boing.
Boeing have been working on a software modification to MCAS since the Lion Air accident. Unfortunately although originally due for release in January it has still not been released due to both engineering challenges and differences of opinion among some federal and company safety experts over how extensive the changes should be. Apparently there have been discussions about potentially adding enhanced pilot training and possibly mandatory cockpit alerts to the package. There also has been consideration of more-sweeping design changes that would prevent faulty signals from a single sensor from touching off the automated stall-prevention system.
The FAA people involved in the process would have been unavailable from December 22 to January 25. Trump personally added a month to the schedule as part of the unintended consequences of his budget shutdown. Boeing can't release squat without FAA approval. Nor can they they resolve any engineering differences when the FAA isn't available. So Boeing should get a pass on at least a month of that delay.
-
Somebody remind me why MCAS is even needed?
This 737 max 8 is presumably empty, but none the less, wow an impressive climb.
Actually, the MCAS was needed in part *because* of those powerful engines. They are more powerful and mounted farther forward than the engines on other 737s, so their power generates a higher turning moment that wants to push the nose up, so the danger of a stall is increased. Furthermore, once you the AOA very high, the nacelles themselves generate some lift (again, with a large moment because of the forward placement relative to the center of rotation), and that pushes for an even higher AOA. This is really only a problem once you are already at high AOA, but essentially the engines themselves become a destabilizing force once you get out of the safe zone.
MCAS is designed to keep the scenario from running away.
Pretty good explanation of why you don't add power immediately after a stall here: https://www.youtube.com/watch?v=TlinocVHpzk (https://www.youtube.com/watch?v=TlinocVHpzk)
Pretty good explanation of why high AOA's are more problematic in the MAX here: https://leehamnews.com/2018/11/14/boeings-automatic-trim-for-the-737-max-was-not-disclosed-to-the-pilots/ (https://leehamnews.com/2018/11/14/boeings-automatic-trim-for-the-737-max-was-not-disclosed-to-the-pilots/)
-
Hmmm, at what point does the Max become a different plane? When you start moving the engines around, changing its dynamics etc...
-
Read this Twitter thread (https://twitter.com/trevorsumner/status/1106934362531155974?s=21) for an interesting take on the root causes. Fuel prices/economic considerations led to a cascde of band aid design and sytems changes each one an attempt to compensate for problems introduced by the prior. The “software patch” is just the latest.
I won’t be surpised to see more of these kind of economics/complexity/systems problems in socierty going forward as there is more and more pressure on engineers to provide technology fixes to underlying economics/resource problems.
-
Read this Twitter thread (https://twitter.com/trevorsumner/status/1106934362531155974?s=21) for an interesting take on the root causes. Fuel prices/economic considerations led to a cascde of band aid design and sytems changes each one an attempt to compensate for problems introduced by the prior. The “software patch” is just the latest.
I won’t be surpised to see more of these kind of economics/complexity/systems problems in socierty going forward as there is more and more pressure on engineers to provide technology fixes to underlying economics/resource problems.
Providing technology fixes to economic problems is pretty much what engineering is. I think "An engineer can do for a dollar what any fool can do for two" is attributed to Arthur Wellington, a well known civil engineer from the late 1800's.
I don't really see the problem with Boeing setting the design goal for the MAX to improve performance without requiring a new type certificate. That the MCAS may be a bad implementation, or the specific engine placement requiring MCAS was a bad idea, or the whole thing has led to complex human+automation failure modes is a sign that maybe they screwed up.
But it is one thing to say that an engineering project failed, quite another to state as SO many have done, IMHO, talking without much knowledge, that the concept itself was doomed to fail. I suspect that in reality, Boeing will implement some fixes and there will be some training, and the MAX will ultimately become a safe airplane like the rest of the 737's.
-
It turns out i personally know someone who lost his family members on the Ethiopian flight.... Cant imagine what that person is going through...
-
I suspect that in reality, Boeing will implement some fixes and there will be some training, and the MAX will ultimately become a safe airplane like the rest of the 737's.
Yes it will, I think so too, but with the MCAS... they royally screwed up.
-
Actually, the MCAS was needed in part *because* of those powerful engines. They are more powerful and mounted farther forward than the engines on other 737s, so their power generates a higher turning moment that wants to push the nose up, so the danger of a stall is increased. Furthermore, once you the AOA very high, the nacelles themselves generate some lift (again, with a large moment because of the forward placement relative to the center of rotation), and that pushes for an even higher AOA. This is really only a problem once you are already at high AOA, but essentially the engines themselves become a destabilizing force once you get out of the safe zone.
I'm struggling with this description. It makes it seem like the new engine placement has a tendency to push the nose of the plane up, and that is the main reason for MCAS.
From the pieces I have gathered, the problem requiring the MCAS is that the engine size and placement altered the aerodymanics of the plane in a way that made it unstable. It's not just a matter of the pilot needed to adjust the trim to adjust for a predictable and steady nose-up tendency. It sounds like the plane becomes unstable in a way that the trim would have to be whacked around up and down in rather large and fast adjustments to make the ride smoother.
In addition to this link posted by mtdoc, I have read another article that suggested the "ride comfort" was adversely affected the the change in engine position, and the MCAS was added to make the flight smoother. But, alas, I have no link.
Read this Twitter thread for an interesting take on the root causes.
Trevor Sumner suggests that the software was never the problem and worked fine. That it was a bandaid that was necessary because of the change in engine placement and the resulting change in aerodynamics. But if anything, it sounds like the software bandaid was indeed part of what turned a "bumpy ride smoother-outer" into a death trap. Yes, the pilots should have cut out the stab trim or what not. And I don't know why there were never informed of the deadly potential problem with the MCAS. But it would have been very trivial (in hindsight) to make MCAS unable to override manual input to such a sustained degree. If it was there to make the ride smoother, then it could have been implemented (thru software) to be able to improve the ride without killing the passengers. Given that a sensor malfunction could have theoretically happened out of the blue at least as low as 6,000 feet and requiring manually turning off the system and course correction within just mere seconds (flipping multiple switches on the roof of the cabin while plummeting towards the earth in near free fall, then cranking the trim wheel bit by bit), it might have happened even with a prepared pilot that knew about the potential fault in advance.
In the light of what I'm inferring, the MCAS system would also have to account for resonant frequencies/oscillations, in addition to sensor malfunction. There would have to be some smarts to it, lets say. Not just a simple if/then cause and effect.
-
Are the new engines so powerful that MCAS is needed or is it purely a bandaid because the weight of the new engines changed the CG too much and they were too cheap to re-locate the wings to the proper place?
-
^that's what I am wondering.
AFAIK, the engines were too big for ground clearance. So to use the existing 737 frame, they had to change the mounting position.
Due to Boeing's philosophy that the plane should be able to fly with only manual control, I assume this means the new engines and mounting position are still safe and stable enough to be flown, manually... but I have inferred (right or wrong) that the ride would be less smooth/comfortable without MCAS.
-
I'm struggling with this description. It makes it seem like the new engine placement has a tendency to push the nose of the plane up, and that is the main reason for MCAS.
That is exactly the reason for MCAS ; safety, not ride comfort. Youtuber Mentour pilot, who is a 737NG captain explains this.
For powered aircraft there is a corner in the flight envelope at high angles of attack called "getting behind the power curve". Aerodynamically past a certain high angle of attack, before full stall the sink rate/drag on the aircraft increases dramatically and if power is applied with low slung engines the pitch up moment makes things worse.
-
If that were the only reason for MCAS, why does it have to rely on a single AOA sensor, rather than the combination of sensors that create the stall warning / stick shake? If it only has to be in effect in near stall conditions, then it should not need to be active unless near a stall.
I'm also struggling with the plane going full throttle. Multiple sources suggest MCAS has control over the elevator with no mention of the throttle.
There are multiple tidbits that suggest to me the MCAS was created to make the ride smoother, which requires a very fast and frequent input to perhaps the throttle in addition to the elevator. Boeing didn't want to offer the 737 MAX and have airliners complain that the ride is bumpier than the old planes?
-
^The US Airforce did experiments with reverse raked wings. This was inherently instable and required active electronic management of some of the control surfaces. This is kind of along the lines of what I am thinking that MCAS was actually made to do... to make faster than human adjustments to reduce the effects of inherent instability. Unlike the reverse wing fighter jets, which had complete runaway instability, perhaps the change in engines created some undesired oscillations between 2 or 3 points of shared stability which were not fatal (until incorrectly MCAS'd) but uncomfortable.
-
If that were the only reason for MCAS, why does it have to rely on a single AOA sensor, rather than the combination of sensors that create the stall warning / stick shake? If it only has to be in effect in near stall conditions, then it should not need to be active unless near a stall.
That the MCAS in default only use a single Angle of attack vane was a mistake by boeing. That stall warning is done with angle of attack sensors (and not "other" sensors) is because it is an aerodynamic phenomenon, not something to do with engines, a common misconception of non-pilots. From what I have read about MCAS, and the Mentourpilot video linked below, you are mistaken if you think MCAS is constantly trimming and flying the plane. It is constantly monitoring the angle of attack but only adding pitch down when it thinks the aircraft is approaching stall. It the recent crashes it looks like the system incorrectly initiated trim down when it didn't need to, and was fighting the pilots.
Have a look at Mentourpilot's video, he dumbs it down too much for my taste but it might help:
https://www.youtube.com/watch?v=TlinocVHpzk (https://www.youtube.com/watch?v=TlinocVHpzk)
-
Actually, the MCAS was needed in part *because* of those powerful engines. They are more powerful and mounted farther forward than the engines on other 737s, so their power generates a higher turning moment that wants to push the nose up, so the danger of a stall is increased. Furthermore, once you the AOA very high, the nacelles themselves generate some lift (again, with a large moment because of the forward placement relative to the center of rotation), and that pushes for an even higher AOA. This is really only a problem once you are already at high AOA, but essentially the engines themselves become a destabilizing force once you get out of the safe zone.
I'm struggling with this description. It makes it seem like the new engine placement has a tendency to push the nose of the plane up, and that is the main reason for MCAS.
Two separate phenomena that I intermingled. Adding power on a 737 when it is in/near a stall will generally make things worse. This is a generic problem with all airplanes with the engines below the wings, but it is certainly a bigger problem with more power at your disposal, and it is a bigger problem with the increased moment of the MAX engine position.
Furthermore, the reason MCAS was specifically designed for the MAX is that the *nacelles* themselves generate lift. (Almost any object in an airstream can generate lift if you hold it the right way.) They are designed to have neutral lift when in level flight, but as you turn the nose of the plane up, the engines actually want to push it up even more, and this is very pronounced at high angles of attack. I'm sure simulations showed that this instability is hard to recover from if not dealt with immediately, hence MCAS.
-
It's a Boeing design error and the S/W patch allowing "the option" of using two sensors stinks of cover-up. AOA DISAGREE alert indicator is also an "option"?! :palm:
Using two sensors is still shitty because you have now doubled the probability of MCAS failure due to a sensor failure.
Multiple sensors iced up for the AF447 disaster. Would MCAS register a discrepancy with two sensors reading similar yet both are out to lunch?
I'll repeat the old adage "with two clocks you can never know the correct time". This MCAS system is never going to be stellar, even adding a third (sensor) opinion because the other pair can malfunction. It's just getting a slightly lower probability of failure, this is all Boeing can accomplish. Unless there was a gross S/W bug that is being fixed too.
In other industries with safety-critical design, you do fault-tree analysis and FMEDA to ensure you have coverage of a sensor problem, among other scenarios.
Clearly, Boeing bungled this and is showing a repeat bungle with their hasty "software fix" that cannot meet basic functional safety requirements even after piling on the algorithm smartness.
I've seen this before - a bad design safety-critical system is out there, sold in numbers and a corporation has a massive panic to fix it ASAP without changing any hardware.
Adding complex S/W algorithms (which can never be proven correct) is very dangerous.
Then I read this: (http://www.b737.org.uk/mcas.htm)
"MCAS is implemented within the two Flight Control Computers (FCCs). The Left FCC uses the Left AOA sensor for MCAS and the Right FCC uses the Right AOA sensor for MCAS. Only one FCC operates at a time to provide MCAS commands. With electrical power to the FCCs maintained, the unit that provides MCAS changes between flights. In this manner, the AOA sensor that is used for MCAS changes with each flight."
How do you come up with something so stupid?
The problem with "MCAS disagree" is that it does not necessarily mean there is a sensor problem. There are aerodynamic situations, such as a steep turn where correctly operating sensors can disagree. Hence, it is a reason to indicate something to the pilot, not a reason for the system to punt. I suspect, though, that the software patch will make it so MCAS will not activate on either sensor indicating high AOA, but only if both indicate high AOA. Well, that's just a guess.
-
That the MCAS in default only use a single Angle of attack vane was a mistake by boeing. That stall warning is done with angle of attack sensors (and not "other" sensors) is because it is an aerodynamic phenomenon, not something to do with engines, a common misconception of non-pilots.
Thanks but I understand that, already. In this case, other sensor could have told the MCAS system that the plane was not stalled. The fact that the plane is going 600 mph in the direction the nose is pointed should be a pretty good indicator of this. I don't know what all sensors that the plane has, but it seems like there are some other ways to detect a stall than the AOA. And the fact the stick shaker did not activate means that the malfunctioning AOA did not fool the stick shaker, right?
Furthermore, the reason MCAS was specifically designed for the MAX is that the *nacelles* themselves generate lift. (Almost any object in an airstream can generate lift if you hold it the right way.) They are designed to have neutral lift when in level flight, but as you turn the nose of the plane up, the engines actually want to push it up even more, and this is very pronounced at high angles of attack. I'm sure simulations showed that this instability is hard to recover from if not dealt with immediately, hence MCAS.
Thanks for this. I think you explained it in your previous post just fine, in hindsight, but I think I understand it better, now. It sounds like the MAX is inherently more prone to getting away from the pilot and stalling at high AOA maneuvers, and it harder to recover from, requiring much greater input to the elevator and less ability to add useful thrust? Essentially, without electronic help, the MAX has less maneuverability. And any electronic aid should only ever need to be fleeting, to bring the plane back from the "runaway" edge of maneuverability. Jacking the elevator full down for 30 seconds seems like a scenario that would be helpful... never? If a pilot is pushing a passenger jet carrying 200 people to the utmost limit, you'd think he has a really, really good and really, really imminent reason... like to avoid hitting something (including the ground).
I am curious why the plane was on full throttle. Do any pilots have a theory here? The plane was supposedly going 600mph and on full thrust. Maybe this is a normal pilot response.
-
A stupid question here: why is MCAS needed in the first place? Isn't the pilot trained to push when the stick shaker is activated? There are some certain scenarios where the pilot must respond without referring the handbook, and they get well trained and well paid for executing those memory checklists well.
What's the problem trusting the pilot? Military planes don't have as much "safety" BS, and they don't fall from the sky for no reason.
Actually they do, quite regularly, not counting combat losses:
https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_military_aircraft_(2010%E2%80%93present) (https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_military_aircraft_(2010%E2%80%93present))
The difference is in the number of casualties and who investigates. In fixed wing combat aircraft, generally all seats are ejection seats, so survival rates are high. In transport aircraft and helicopters, there are still far fewer people involved in most cases.
-
I am curious why the plane was on full throttle. Do any pilots have a theory here? The plane was supposedly going 600mph and on full thrust. Maybe this is a normal pilot response.
Well if you know that engine thrust on the aircraft tends to push the nose up, and one is desperately trying to get the nose up, it makes some sense to pour on the throttle to get the nose up.
-
And another question: if there is a huge structural error in this plane, why did "only" two planes crash in half a year time ?
Are there more incidents, reports from pilots that just in time got the plane under control by disabling the computer and take manual control? Haven't heard about them ?
-
And another question: if there is a huge structural error in this plane, why did "only" two planes crash in half a year time ?
Are there more incidents, reports from pilots that just in time got the plane under control by disabling the computer and take manual control? Haven't heard about them ?
Yes, there are reports of at least two other pilots that have had to deactivate MCAS during takeoff.
Edit: Not the MCAS, had to disable the autopilot it seems:
http://time.com/5550449/pilots-boeing-737-max-issues/ (http://time.com/5550449/pilots-boeing-737-max-issues/)
-
And another question: if there is a huge structural error in this plane, why did "only" two planes crash in half a year time ?
From what we know so far the MCAS becomes a problem if the angle of attack sensor gives a false reading. I sure hope the sensor is not *that* bad.
A sensor meeting the "major failure" safety requirement must have a failure rate less than 1/100000. Are there any statistics of how many total 737 MAX flights have occurred since its launch?
-
Yes, there are reports of at least two other pilots that have had to deactivate MCAS during takeoff.
Ok 5 incidents in a half year for 350 planes flying at least two flights a day , so 5 incidents over 127000+ flights.
EDIT: the plane has been in service since 2016 so that would be miliions of flights and only now it occurs.
Don't get me wrong it is good to get to the bottom of this, but it looks like it will be pretty hard to exactly determine the cause if it only happens under certain very specific conditions.
Good that the flightrecorders are there, otherwise it would be a needle in a haystack.
There are approximately 350 Boeing 737 Max 8 aircraft in operation worldwide, being flown by 54 operators, according to the US Federal Aviation Administration (FAA).5 days ago
-
it looks like it will be pretty hard to exactly determine the cause...
Or... maybe not.
https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ (https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/)
Apologies if someone else has already linked this. It seems like it was published within the last 18 hours. It seems pretty clear, so far. It contains almost all the important details in this thread but without the faff.
1. FFA let Boeing approve its own plane, in some ways.
2. The MCAS was said to move the elevator only 0.6 degrees. But Boeing increased it to 2.5 degrees after test flights. No one told this to the FAA.
3. After the elevator is manually moved by the pilot, the MCAS can re-trigger. Doing a full 2.5 degrees again. (In the Ethiopian Airlines flight, the captain corrected the plane 21 times, then he handed the plane to the FO. The FO made only a tiny, partial correction after MCAS triggered. Then it triggered again. This put the elevator to full nose down, and the plane crashed shortly after.)
4. Boeing didn't include info about MCAS to its customers, at all.
5. MCAS was probably incorrectly classified. FFA approved the original classification based on 0.6 degrees of elevator adjustment. That changed to 2.5 (and was actually unlimited, due to retriggering). And even they way it was initially classified, it still needed to have two sensors, not just one.
6. They didn't consider the human factor of what happens to a pilot when 2.5 degrees of elevator adjustment is made out of the blue and repeatedly retriggers and no one told them this could even happen. 5 degrees is basically maximum nose dive; so I think "panic" might be on the menu. I wonder how many 737 commercial (not test) pilots have ever intentionally used even 2.5 degree downward angle on a flight.
So basically, this MCAS system, in the hands of a pilot who has spent 6,000 hours of flight time living by very small and gradual adjustments and essentially "not messing up", becomes a shoddy encoder wheel, where you manage to turn the volume up by 1, then it goes down by 10, then up by 1, then down by another 10. And then the music stops playing.
-
Yes, there are reports of at least two other pilots that have had to deactivate MCAS during takeoff.
Ok 5 incidents in a half year for 350 planes flying at least two flights a day , so 5 incidents over 127000+ flights.
EDIT: the plane has been in service since 2016 so that would be miliions of flights and only now it occurs.
Don't get me wrong it is good to get to the bottom of this, but it looks like it will be pretty hard to exactly determine the cause if it only happens under certain very specific conditions.
Good that the flightrecorders are there, otherwise it would be a needle in a haystack.
There are approximately 350 Boeing 737 Max 8 aircraft in operation worldwide, being flown by 54 operators, according to the US Federal Aviation Administration (FAA).5 days ago
The first 737 MAX commercial flight was in May, 2017. Wherever you got 2016 from was probably publicity about the aircraft making test flights.
You might find these easy-to-find numbers more useful: https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries (https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries)
-
Thanks but I understand that, already. In this case, other sensor could have told the MCAS system that the plane was not stalled. The fact that the plane is going 600 mph in the direction the nose is pointed should be a pretty good indicator of this. I don't know what all sensors that the plane has, but it seems like there are some other ways to detect a stall than the AOA. And the fact the stick shaker did not activate means that the malfunctioning AOA did not fool the stick shaker, right?
Other sensors might inform the MCAS software that the the aircraft is in a "this can't happen" situation but then what. I suspect the flight law software would choose to believe the angle of attack indicator over conflicting information as they should be more reliable than the rest. For what it is worth the stall horn in piston aircraft is a very simple reliable device, it roughly forms the same function. As the angle of attack approaches stall the vane rotates and a noise is made, then the pilot needs to take action and lower the nose.
The problem in 737Max case is that MCAS kicks in and starts quietly adding downward trim before the stick shaker angle of attack. And as far as I know this only this happens in manual flight mode. This was poorly explained to the pilots who's first reaction would be to countermand that input with opposite trim with the trim hat on the yoke. That apparently is not the way you disable MCAS and it keeps on fighting your inputs.
-
3. After the elevator is manually moved by the pilot, the MCAS can re-trigger. Doing a full 2.5 degrees again. (In the Ethiopian Airlines flight, the captain corrected the plane 21 times, then he handed the plane to the FO.
Fuck me drunk. I'm sorry. What ?? 21 times??
"Here, the thing is fucked and we're all going to die. You deal with it".
-
3. After the elevator is manually moved by the pilot, the MCAS can re-trigger. Doing a full 2.5 degrees again. (In the Ethiopian Airlines flight, the captain corrected the plane 21 times, then he handed the plane to the FO.
Fuck me drunk. I'm sorry. What ?? 21 times??
"Here, the thing is fucked and we're all going to die. You deal with it".
Wrong take on it. It was more likely something along the lines of, "My controls aren't working right, try yours!" Which is a perfectly reasonable thing to try. Redundancy on all the primary flight controls and instruments from side to side is deliberate, just in case one side breaks in some way.
-
Are the new engines so powerful that MCAS is needed or is it purely a bandaid because the weight of the new engines changed the CG too much
It can take off like a Vulcan bomber:
https://youtu.be/RyeqeqSNSgQ
-
Wrong take on it. It was more likely something along the lines of, "My controls aren't working right, try yours!" Which is a perfectly reasonable thing to try. Redundancy on all the primary flight controls and instruments from side to side is deliberate, just in case one side breaks in some way.
Yep. Not a pilot and done nothing more than a couple of (really fun) lessons in a Cessna, so happy to take that. Still, the difference between the Captain trying 21 times and the first officer pushing it into the dirt is peculiar.
-
It can take off like a Vulcan bomber:
Wowzers. The video says the plane experiences zero gravity when it leveled off. If you could get all the passengers to sign a waiver, I'd be the first one to.... watch the cell phone videos.
-
It can take off like a Vulcan bomber:
Wowzers. The video says the plane experiences zero gravity when it leveled off. If you could get all the passengers to sign a waiver, I'd be the first one to.... watch the cell phone videos.
Getting to negative G is trivial to do in any aircraft, even a glider. It doesn't have anything to do with the climb rate.
-
Standard airshow stuff for new planes. Light fuel load and a completely empty cabin. Even the passenger seats and cabin trim may be missing. Much bigger power to weight ratio than a normal commercial takeoff.
-
It can take off like a Vulcan bomber:
Now that really was something to experience! I remember an airshow at RAF Finningley when I was a kid, back when they were still fully operational. One gently cruised in at low level and then, half way along the runway, just sat on its tail and went up almost vertically. The feeling of my chest being forcibly compressed completely overwhelmed the indescribable roar.
It left a lasting impression even after all these years, I've never experienced anything like it again. That level of noise exposure would never be allowed these days of course.
Sorry, OT.
P.S. I saw its last airshow at Yeovilton. Sadly, they were very gentle on the airframe and engines, they did deploy the parachute though.
-
Standard airshow stuff for new planes. Light fuel load and a completely empty cabin. Even the passenger seats and cabin trim may be missing. Much bigger power to weight ratio than a normal commercial takeoff.
A long time ago, I flew in a British Midland 747 from San Diego to LHR. The aircraft had flown from LHR to LAX, then the little hop down to San Diego to drop off the last few passengers. It took off with about 30 passengers on board, and hardly any fuel. Whoosh....
-
Standard airshow stuff for new planes. Light fuel load and a completely empty cabin. Even the passenger seats and cabin trim may be missing. Much bigger power to weight ratio than a normal commercial takeoff.
A long time ago, I flew in a British Midland 747 from San Diego to LHR. The aircraft had flown from LHR to LAX, then the little hop down to San Diego to drop off the last few passengers. It took off with about 30 passengers on board, and hardly any fuel. Whoosh....
Qantas used to fly LAX->AKL->MEL, one day by chance I happened to hop on the AKL->MEL leg, after the vast majority of passengers & cargo had left, along with the light fuel load for such a short hop it took off like the proverbial bat out of hell.
One of my favourite flying memories.
-
^The US Airforce did experiments with reverse raked wings. This was inherently instable and required active electronic management of some of the control surfaces. This is kind of along the lines of what I am thinking that MCAS was actually made to do... to make faster than human adjustments to reduce the effects of inherent instability. Unlike the reverse wing fighter jets, which had complete runaway instability, perhaps the change in engines created some undesired oscillations between 2 or 3 points of shared stability which were not fatal (until incorrectly MCAS'd) but uncomfortable.
Seams both US X29 and Sovjets SU47 got raked wing concept from Junkers Ju287 which all of them suffered from warping wings at certain flight conditions which a MCAS would not fix i presume.
https://www.youtube.com/watch?v=mOCUTyoi9eo (https://www.youtube.com/watch?v=mOCUTyoi9eo)
-
But, because these sticks are not coupled and do not have any force feedback, the pilots did not know what the other one was doing.
This is something that has always struck me as an absolutely stupid design. If the plane has two sticks, they should absolutely be mechanically linked together, or only one set of controls should be active at a time, with a very obvious indication of which is active. I never liked the sidestick arrangement anyway, it just looks wrong, and seems like it would be awkward.
Actually in most modern passenger aircraft the left controls are connected to the left elevator, the right controls, right elevator and there's a sheer pin that can be broken (on purpose) if there's a jam, so that each side independently controls elevators; everything from roughly Dash-8 and bigger. Egypt Air 990 was a case where this was highlighted in what appears to be pilot v pilot fight for the aircraft.
-
Standard airshow stuff for new planes. Light fuel load and a completely empty cabin. Even the passenger seats and cabin trim may be missing. Much bigger power to weight ratio than a normal commercial takeoff.
A long time ago, I flew in a British Midland 747 from San Diego to LHR. The aircraft had flown from LHR to LAX, then the little hop down to San Diego to drop off the last few passengers. It took off with about 30 passengers on board, and hardly any fuel. Whoosh....
I used to do a fairly regular trip to Cork airport from LHR. Cork is a small airport built on the top of a hill (you can't see one end of the runway from the other, subject to low cloud too). On days with unfavourable wind direction and speed (frequent) taking of from Cork used to involve bringing the tanker out, taking fuel off the plane (737) and using the short cross runway... Taxi right to the very end, turn without going onto the grass, full brakes, full throttle and release. As you say, "Whoosh...."
The plane would then fly to Shannon (much bigger, international flights), to fill up with sufficient fuel to fly back to LHR. I kid you not!
This was back in the '80s https://en.wikipedia.org/wiki/Cork_Airport (https://en.wikipedia.org/wiki/Cork_Airport)
-
It sounds like the MAX is inherently more prone to getting away from the pilot and stalling at high AOA maneuvers, and it harder to recover from, requiring much greater input to the elevator and less ability to add useful thrust?
Yes, I think this is basically true, but the caveat is that it gets unstable once you've already gotten it into a high AOA situation, which in normal ops should not happen. You might say that a pilot's #1 one job flying and airplane is keeping the wing flying, so this defect -- that the plane is a problematic performer at high AOA -- is perhaps less of an operational defect than it seems.
Essentially, without electronic help, the MAX has less maneuverability.
Again, this is not an airshow stuntplane, it's maneuverability at high AOA isn't generally that important, because it's not supposed to be there. And indications so far from these accidents is that the plan did not have high AOA when the problem kicked in. A faulty sensor made it *think* it was experiencing high AOA.
If a pilot is pushing a passenger jet carrying 200 people to the utmost limit, you'd think he has a really, really good and really, really imminent reason... like to avoid hitting something (including the ground).
History has shown it both ways. Sometimes a pilot correctly pushes a plane beyond its safe envelope because of good reason that requires it, sometimes pilots have caused accidents by doing so.
-
The problem in 737Max case is that MCAS kicks in and starts quietly adding downward trim before the stick shaker angle of attack. And as far as I know this only this happens in manual flight mode. This was poorly explained to the pilots who's first reaction would be to countermand that input with opposite trim with the trim hat on the yoke. That apparently is not the way you disable MCAS and it keeps on fighting your inputs.
I'm not quite certain of this, but I believe in the Lionair case, the published data show that the stick shaker was going on one side. I haven't seen the ET data yet. I'd be surprised if MCAS before the stick shaker kicks in, but there's a lot surprising in these accidents.
-
It can take off like a Vulcan bomber:
Now that really was something to experience! I remember an airshow at RAF Finningley when I was a kid, back when they were still fully operational. One gently cruised in at low level and then, half way along the runway, just sat on its tail and went up almost vertically. The feeling of my chest being forcibly compressed completely overwhelmed the indescribable roar.
It left a lasting impression even after all these years, I've never experienced anything like it again. That level of noise exposure would never be allowed these days of course.
Sorry, OT.
P.S. I saw its last airshow at Yeovilton. Sadly, they were very gentle on the airframe and engines, they did deploy the parachute though.
I used to have workshop 400 meters from the main runway at RAF Marha,Marham Norfolk, all the air shows by the Vulcan bomber as the ground control officer was based there so I used to see the vulcan doing it's thing several times a year over about a 15 year period. Also saw and heard the Victor tankers taking off at all times of the day and night as with the Canberra's reconosance and the Tornado's, The noise level was so graet at times that it caused mortar to run down the walls, the engine run up area was less than 50 meters from my workshop. The only good side was the neighbors did complain about any noise I made at any time of day or night in the workshop.
-
It's terrible to see engineers forced to either roll out unsafe shit, or lose their job.
The managers, executives etc. suffer little for their corruption, even when caught. One or two people might get fined or some jail time, despite hundreds killed.
Further proof is the way Boeing is handling things, as a "software upgrade" which doesn't even cover the AOA sensors having poor reliability in the first place.
-
Further proof is the way Boeing is handling things, as a "software upgrade" which doesn't even cover the AOA sensors having poor reliability in the first place.
Wait, wait... perhaps it's not the sensors' fault, but a software bug.
-
A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump))
...
Every time politicians, MBAs and managers meddle with technical issues something fails.
"... participated in phone conversations with top Boeing executives and other stakeholders, offering his thoughts on the aviation industry. But since then, he has faced criticism that his over-involvement stymied the FAA from acting sooner. "
Nooooooh! :palm:
-
Further proof is the way Boeing is handling things, as a "software upgrade" which doesn't even cover the AOA sensors having poor reliability in the first place.
Wait, wait... perhaps it's not the sensors' fault, but a software bug.
The AOA sensor is first in the chain of events, it triggers the MCAS software. Unless the flight control software has huge bugs...
MCAS I thought only activates in manual mode, and the prior complaints by two pilots had problems when autopilot was engaged, when MCAS should be disabled then.
Also, autothrottle did not work in one instance. This implies there's some other problem.
https://www.washingtonpost.com/business/economy/sensor-cited-as-potential-factor-in-boeing-crashes-draws-scrutiny/2019/03/17/5ecf0b0e-4682-11e9-aaf8-4512a6fe3439_story.html?noredirect=on&utm_term=.271f3763b148 (https://www.washingtonpost.com/business/economy/sensor-cited-as-potential-factor-in-boeing-crashes-draws-scrutiny/2019/03/17/5ecf0b0e-4682-11e9-aaf8-4512a6fe3439_story.html?noredirect=on&utm_term=.271f3763b148)
-
Even if there's no software bug, even if the AOA sensor is the most reliable sensor on the plane, there is an error in the design/implementation. If software bugs are also discovered, oh boy. Not that the engineers are the fault. Mistakes happen, and that is why the approval process (normally) takes as long as it does.
A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump))
Sure, Boeing is going to be "Shenzu Air" after Chinese investors buy it. J/K. They'll get a government bailout, if it comes to that. Maybe one scapegoat goes to jail for 2 years. But what about the FAA? Surely a bunch of those guys can be liberated from the federal payroll and offered some time behind bars for endangerment of human life if not bribery. And who knows how high up this goes into the government? Does it even end at the FAA?
-
Even if there's no software bug, even if the AOA sensor is the most reliable sensor on the plane, there is an error in the design/implementation. If software bugs are also discovered, oh boy. Not that the engineers are the fault. Mistakes happen, and that is why the approval process (normally) takes as long as it does.
A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump))
Sure, Boeing is going to be "Shenzu Air" after Chinese investors buy it. J/K. They'll get a government bailout, if it comes to that. Maybe one scapegoat goes to jail for 2 years. But what about the FAA? Surely a bunch of those guys can be liberated from the federal payroll and offered some time behind bars for endangerment of human life if not bribery. And who knows how high up this goes into the government? Does it even end at the FAA?
You guys seem awfully sure that Boeing and the FAA worked together to sell an airplane they knew was unsafe. I'll agree, I think that if that is proven, the punishment should be very severe. But I think you do not need that kind of behavior to produce a bad outcome. I think it's interesting that so many people do. What incentive do either of those organizations have to certify a passenger killing machine?
-
Airlines want safety, but with margins so slim, they are forced to worry about their bottom line. And the FAA wants safety, but needs to weigh the Cost-Benefit of each new advance. So in the end, it is often Tombstone Technology and accidents -- that drive the industry forward.
-
Can there be a 737 Max pilot that does not know about MCAS and how to respond when it acts up anywhere in the world at this point?
Did Boeing actually send out mandatory to read information to airlines explaining the MCAS system after the first accident? Or would those pilots have to have followed the news, with all its inaccuracies?
If Boeing continued to pretend that pilots really didn't need to know there was an automatic control in a plane where pilots very much expect there not to be one, that's still on them.
-
Uh hu..
The 737 MAX Saga Is a Total Disgrace for Boeing and the FAA (https://libertyblitzkrieg.com/2019/03/18/the-737-max-saga-is-a-total-disgrace-for-both-boeing-and-the-faa/)
This whole affair seems like a perfect microcosm for our twisted and broken modern U.S. economy and culture in general. Greed, regulatory capture and death — it has it all.
-
Even if there's no software bug, even if the AOA sensor is the most reliable sensor on the plane, there is an error in the design/implementation. If software bugs are also discovered, oh boy. Not that the engineers are the fault. Mistakes happen, and that is why the approval process (normally) takes as long as it does.
A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump))
Sure, Boeing is going to be "Shenzu Air" after Chinese investors buy it. J/K. They'll get a government bailout, if it comes to that. Maybe one scapegoat goes to jail for 2 years. But what about the FAA? Surely a bunch of those guys can be liberated from the federal payroll and offered some time behind bars for endangerment of human life if not bribery. And who knows how high up this goes into the government? Does it even end at the FAA?
Mmkaay, now FBI with special counsel Miiuulleeerr and DOJ is setting up a investigation to Russian collusion as they suspect Piutin has caused the MCAS software bug. 2 years later no collusion was found and Miiuulleer refuses to release clown report while Dumpf having tea and cakes with Boing CEO..
-
Perhaps already posted, just in case:
https://www.eetimes.com/author.asp?section_id=36&doc_id=1334444 (https://www.eetimes.com/author.asp?section_id=36&doc_id=1334444)
-
The Hudson river landing was a good example of why pilots need an internalized model of the flight system and why arcane rote procedures to deal with failures are not enough.
-
I used to have workshop 400 meters from the main runway at RAF Marha,Marham Norfolk, all the air shows by the Vulcan bomber as the ground control officer was based there so I used to see the vulcan doing it's thing several times a year over about a 15 year period. Also saw and heard the Victor tankers taking off at all times of the day and night as with the Canberra's reconosance and the Tornado's, The noise level was so graet at times that it caused mortar to run down the walls, the engine run up area was less than 50 meters from my workshop. The only good side was the neighbors did complain about any noise I made at any time of day or night in the workshop.
OHS came around one day where I was, to measure sound levels. Coincidentally there was an Atar 09k50 in the test bed being given an after service check. Started, run till warm then the full power with full afterburner test while they were measuring sound pressure levels in the complex. 130dB plus, a half kilometer away from the test bed, and nobody noticed it as it was normal.
Now scary was when I accidentally got a flight in an aircraft that officially did not exist, and we needed all 4km of runway, plus a little more, to take off. Was a very interesting flight, but again, no cameras were allowed.
-
The Hudson river landing was a good example of why pilots need an internalized model of the flight system and why arcane rote procedures to deal with failures are not enough.
This, I think is the first good argument I've heard for why 737 pilots need to know about MCAS.
As it happens, during the USAir 1549 landing, the A320's control systems did not let Sullenberger flare the way he had wanted to. The outcome was fine, but if the system had been more aggressive in "protecting the envelope" maybe it would not have been. At least he knew what the system would do.
https://www.youtube.com/watch?v=cKuw49KBywA (https://www.youtube.com/watch?v=cKuw49KBywA)
But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.
-
But, because these sticks are not coupled and do not have any force feedback, the pilots did not know what the other one was doing.
This is something that has always struck me as an absolutely stupid design. If the plane has two sticks, they should absolutely be mechanically linked together, or only one set of controls should be active at a time, with a very obvious indication of which is active. I never liked the sidestick arrangement anyway, it just looks wrong, and seems like it would be awkward.
Actually in most modern passenger aircraft the left controls are connected to the left elevator, the right controls, right elevator and there's a sheer pin that can be broken (on purpose) if there's a jam, so that each side independently controls elevators; everything from roughly Dash-8 and bigger. Egypt Air 990 was a case where this was highlighted in what appears to be pilot v pilot fight for the aircraft.
You're not likely to break that shear pin without knowing it though. On the Airbus planes the two sticks are not mechanically linked in any way at all, if one pilot is pulling back or pushing forward hard on their stick you wouldn't know by holding yours.
-
Mmkaay, now FBI with special counsel Miiuulleeerr and DOJ is setting up a investigation to Russian collusion as they suspect Piutin has caused the MCAS software bug. 2 years later no collusion was found and Miiuulleer refuses to release clown report while Dumpf having tea and cakes with Boing CEO..
I like my tinfoil hats, so fair enough. But wait and see. FAA was fasttracking these approvals because someone was poking/pressuring them and or there was some major personal interest or incentive. Maybe Boeing hires retired FAA officials as consultants, and that is enough. Maybe there's more inbreeding and impropriety than that, even. I imagine Boeing is a very important company to our country's military and government.* And somehow many people were actively not doing their jobs and looking the other way.
*Transportation Secretary Elaine Chao even rode in a 737 MAX two days after the latest crash.
-
But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.
That is the whole point is it not? According to that eetimes article Boeing claimed that any experienced 737 pilot did not need additional training or simtime for the max.
That is also why it was a big seller, the airlines did not have to invest in hours of training and that was a massive saving. It is also probably in the future the reason that if there has to be substantial additional training, the airlines will cancel their orders.
-
But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.
In this case, experiencing/simulating what the plane does in an extreme handling situation is not enough. They should need to experience what it is like not only when MCAS kicks in during the edge of stall. The training should also include the MCAS kicking in "out of the blue" during routine flight. This is a completely different experience with potentially very little time to react. If the plane pulls more than 1 negative G during this malfunction, it is going to be hard to even simulate. Reading a manual and sim might not even be enough, because of "instinctual" or automatic human response. Simulation is good, but now do it when you're cruising along with everything normal when the floor drops out from under you, you are disoriented, and the first and foremost thing being pressed onto your adrenaline soaked pea brain as you regain your orientation is the ground ending your life within the next 25 seconds unless you fix the problem within the first few of those seconds. And all the while you hear the screams of 200 passengers who are sure they're about to die through the cabin wall.
Military helicopter pilots are trained to evacuate the vehicle in a water crash, and the only effective simulation involves a giant tank of water and a fake helicopter that spins and dunks them upside down in the water. Apparently, only a small percentage of trainees make it out on the first try, even though they know exactly what is coming and when. This training greatly increased the survival rate of pilots in water landings. Simply knowing what to do and practicing under normal conditions did not help.
-
But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.
That is the whole point is it not? According to that eetimes article Boeing claimed that any experienced 737 pilot did not need additional training or simtime for the max.
That is also why it was a big seller, the airlines did not have to invest in hours of training and that was a massive saving. It is also probably in the future the reason that if there has to be substantial additional training, the airlines will cancel their orders.
Yes, that was the aircraft's goal and claim. And pilots are really trained these days to avoid the need for heroic mastery of ship's aerodynamics rather than trying to achieve such mastery. Today's pilots just don't have great stick and rudder skills, and that's turned out to be safe for the most part because other than trying to fly actually broken or malfunctioning aircraft, such skills rarely come up. They do, from time to time: USAir 1549, good outcome, AF447, bad outcome.
MCAS was designed to keep pilots from ever experiencing the instability of a MAX at extreme AOA. This was probably judged safer than trying to teach pilots to deal with it. Folks are saying that was not a sound engineering decision and I think they don't generally know what they're talking about. These are complex decisions, and history and human factors, and what can be expected of 1 std dev below mean pilots all figure into it.
But MCAS introduced a new failure mode (or modes) of its own, due to mistakes or poor enginneering, or reasons still unknown, and pilots have obviously not been able to handle that. The solution could be training on these failure modes or it could be fixing MCAS, or all of the above.
-
It seems to me they're going to end up needing additional training no matter what. Especially if these two accidents turn out to be caused by MCAS malfunctions, the pilots absolutely need to know what to do in the event that system fails and how to override it.
As far as stick & rudder skills, IMHO knowing how to deal with failures and fly by hand when necessary is exactly the reason we have professional pilots in the cockpit rather than an operator just skilled enough to monitor the automated systems. I worry that too much automation, not just in planes but now in cars too becomes a crutch, enabling people to become complacent and dependent on the technology and unable to step in when the technology inevitably fails in certain edge cases.
-
Here in NZ pilot skills are assessed as in you're critiqued constantly by one another and have a few trips to the sim each year where assessment jumps to another level.
In the sim you're thrown all sorts of swerve balls and emergency situations that in particular the Captain must master.
Trouble is, if a particular situation is not able to be simulated pilots must refer to their basic flying skills in order to sort it out but if the plane is fighting them thinking it knows better, well Houston, we have a problem.
-
MCAS was designed to keep pilots from ever experiencing the instability of a MAX at extreme AOA.
It was introduced for a reason (https://en.wikipedia.org/wiki/Boeing_737_MAX#Maneuvering_Characteristics_Augmentation_System_(MCAS)) - due to forward & up engine placement of MAX (compared to older models) which cause an upward pitching moment that leads to increased AOA and risk of stall. Some facts regarding Flight 302 are interesting: plane crashed with MCAS in "full nosedive mode", yet during last moments of flight plane gained altitude and speed according to flightradar24 data (https://graphics.reuters.com/ETHIOPIA-AIRPLANE/0100911Q1DX/index.html). Pilots have option to disengage automatic stabilizer trim and crank it mechanically using wheel, but seems that instead of taking control over MCAS, they simply fought it - continued to climb at full(?) throttle, reached high speeds with stabilizer in nosedive position and lost control over plane. [all this just speculation of armchair investigator]
-
Pilots have option to disengage automatic stabilizer trim
An option they didn't think was relevant with the autopilot turned off.
-
Pilots have option to disengage automatic stabilizer trim
An option they didn't think was relevant with the autopilot turned off.
I don't think that's true. The trim wheels are moving by themselves. They are large and very obvious when turning. They also make a loud clacking. That is it dead obvious that the machine is retrimming the stab. You might not know why it is happening, but you know that it is. And the procedure to make it stop no matter the reason is simple. You don't need to know what subsystem is commanding the stab trim to disable it.
If the pilots wanted to disconnect the trim motors, they could have easily. That they didn't is a mystery that the CVRs will hopefully reveal. But I suspect the reason was that they weren't completely sure the machine didn't have a good reason to do what it was doing. They're trained to avoid stalls, and if the machine is saying down, down, down, you have to be really confident you know better to disconnect it entirely.
-
If the pilots wanted to disconnect the trim motors
That's a different switch though, the autopilot trim switch was in their mind irrelevant.
-
Prediction: The 737 Max will not fly again.
-
I would bet it will be back in the air within a few months. Worst case they remove MCAS and re-certify, there appears to be nothing inherently wrong with the aircraft, it just handles a bit differently than the 737 classic. The DC-10 had teething problems that included several deadly crashes within a short period and went on to become a successful aircraft, along wit the MD-11 that evolved from it.
-
I would bet it will be back in the air within a few months. Worst case they remove MCAS and re-certify, there appears to be nothing inherently wrong with the aircraft
Problem is that it seems it is unstable and thats the reason for developing the MCAS.
As for the software update it doesn't matter what Boeing comes up with, it will be under harsh scrutiny of pilots, regulatory agencies and airlines worldwide. It may even make its way to Stackoverflow for discussion who knows ::).
It's not unstable, the only problem is the bug in MCAS that makes it push nose down relentlessly for no reason and crash, but not the dynamics of the plane.
-
Prediction: The 737 Max will not fly again.
But that would be game over for Boeing...
-
But that would be game over for Boeing...
or the government would have to bail them out from US taxpayers money because it is an to important industry to loose like they did with some banks (so far for capitalism and each should hold up its own).
-
Prediction: The 737 Max will not fly again.
There’s a precisely zero percent chance of this outcome.
-
Prediction: The 737 Max will not fly again.
There’s a precisely zero percent chance of this outcome.
I would not be so sure.
The reputation of the name "737 Max" is already pretty much destroyed.
They might do some small alterations and rename the model to for instance 737 Plus or something like that, in that case mtdoc's prediction has become reality.
-
Prediction: The 737 Max will not fly again.
There’s a precisely zero percent chance of this outcome.
I agree.
I would not be so sure.
The reputation of the name "737 Max" is already pretty much destroyed.
They might do some small alterations and rename the model to for instance 737 Plus or something like that, in that case mtdoc's prediction has become reality.
That could always be a possibility - but I doubt it will go that far. If Boeing bury the problem name and re-badge the airframe, it is going to be patently obvious as an attempt to hide the embarrassment. I believe they need to brace themselves and take the flak head on - and I think it is clear they are going to cop some.
-
It is going to be interesting to see the "game" commence, who is going to resign, who is fired, who is getting the blame.
But in the end Airbus survived their computer-erroneous crashes, so I do not see why Boeing would be different.
-
Some rumors about the audio recordings and flight data records:
https://www.reuters.com/article/us-indonesia-crash-exclusive/exclusive-cockpit-voice-recorder-of-doomed-lion-air-jet-depicts-pilots-frantic-search-for-fix-sources-idUSKCN1R10FB (https://www.reuters.com/article/us-indonesia-crash-exclusive/exclusive-cockpit-voice-recorder-of-doomed-lion-air-jet-depicts-pilots-frantic-search-for-fix-sources-idUSKCN1R10FB)
In short: Looks like the nose was pushed down by the trim system and they didn't recognize it, and needed too long to read the manual how to fix it. The evening before another crew had the same problem, but they knew how to fix it, but apparently didn't tell the new crew about the problem.
Isn't there some regulation to report all problems, and for the new crew to read all reports? When I'm watching bus driver changing, they always ask and tell each other if there is a problem with the bus or on the route. I would have thought that's even more verbose for planes.
-
No doubt, the pilots are to blame too. After the 610 flight crash they should have known better and disable the damn thing at the first sign.
-
It's not unstable, the only problem is the bug in MCAS that makes it push nose down relentlessly for no reason and crash, but not the dynamics of the plane.
I beg to differ, The software was designed to compensate for a new instability that resulted from some small physical-design modification and MCAS was added to comply with airworthiness certification
Exactly. Pushing nose down to decrease AOA and avoid stall is function of MCAS, not bug. Main question here is: it was bad decision of MCAS due to faulty AOA sensor or bad decision of pilots to fight MCAS or maybe both. If instruments scream that stall is imminent, plane itself is pushing nose down to decrease AOA but you gain altitude and speed instead (thus increase AOA) - it is very strange thing to do to say it politely.
[edit] Who the hell runs life-critical system from input of just two sensors single sensor (https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/)?! - Even automobile airbags have better redundancy (AFAIK).
-
https://www.youtube.com/watch?v=l0WG0B2JYLQ (https://www.youtube.com/watch?v=l0WG0B2JYLQ)
-
The reputation of the name "737 Max" is already pretty much destroyed.
Nah. You'd still fly on a 787 despite the battery fires?
The 777 with engine icing?
What about a DC10 (ok, the final ones are now out of passenger service) after all the cargo door incidents?
The earlier 737s with rudder hard-over?
These things happen with new models, and are usually fixed.
As others have said, the 737MAX is a bit of a hack to keep the line going to compete with the re-engined A320 series, Boeing's plan was to do a fresh design so they could throw away a bunch of the legacy the 737 type certificate, but they decided that would give them a risk of losing customer to Airbus.
Their big hope in this space is probably the MOM airplane plan goes very well, enough to justify a shrink variant that would fit in 737 gates and share a type certificate (similar to the 757/767 days).
-
Both planes crashed in presumably hot climate. Could that have to do with the angle of attack sensors failing?
-
https://www.bloomberg.com/news/articles/2019-03-19/how-an-extra-man-in-cockpit-saved-a-737-max-that-later-crashed (https://www.bloomberg.com/news/articles/2019-03-19/how-an-extra-man-in-cockpit-saved-a-737-max-that-later-crashed)
As the Lion Air crew fought to control their diving Boeing Co. 737 Max 8, they got help from an unexpected source: an off-duty pilot who happened to be riding in the cockpit.
That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane, according to two people familiar with Indonesia’s investigation.
The next day, under command of a different crew facing what investigators said was an identical malfunction, the jetliner crashed into the Java Sea killing all 189 aboard.
The presence of a third pilot in the cockpit wasn’t contained in Indonesia’s National Transportation Safety Committee’s Nov. 28 report on the crash and hasn’t previously been reported.
-
Prediction: The 737 Max will not fly again.
In the early 90s a design flaw in 737s caused at least two fatal crashes (0) and yet here we are.
Having said that, this time round things might be different. The FAA is seen to be compromised (1):
As Boeing hustled in 2015 to catch up to Airbus and certify its new 737 MAX, Federal Aviation Administration (FAA) managers pushed the agency’s safety engineers to delegate safety assessments to Boeing itself, and to speedily approve the resulting analysis.
But the original safety analysis that Boeing delivered to the FAA for a new flight control system on the MAX — a report used to certify the plane as safe to fly — had several crucial flaws.
Other agencies will not accept the FAA's certification of the software modification which will cause some delays in the return to flight. The agencies may also reject the FAA's original certification of the 737 MAX and require Boeing to go directly to them for certification (2). If so it will be months or years before the 737 MAX flies in those areas, though it will probably return to flight in the US in a few months.
I recommend reading the Seattle Times article (1). It is hair-raising and what they describe might explain how Boeing chose to activate MCAS off a single sensor even though the why mystifies everyone they asked.
An older article in the same paper (3) discuses the fact that the symptoms of MCAS activation are different to previous runaway trim failures and how this might have flumoxed the Lion Air pilots, both on the accident flight and on the previous flight. That previous flight didn't crash but the pilots were unable to diagnose what was wrong and why what they did worked.
Of course, at this stage we don't know what happened in the second crash and the final verdict is not yet in on the first. The pilots on the Ethiopian flight had information not available to the pilots on the Lion flight.
(0) https://en.wikipedia.org/wiki/Boeing_737_rudder_issues (https://en.wikipedia.org/wiki/Boeing_737_rudder_issues)
(1) https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ (https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/)
(2) https://globalnews.ca/news/5072383/canada-eu-reviewing-certification-boeing-737-max/ (https://globalnews.ca/news/5072383/canada-eu-reviewing-certification-boeing-737-max/)
(3) https://www.seattletimes.com/business/boeing-aerospace/faa-evaluates-a-potential-design-flaw-on-boeings-737-max-after-lion-air-crash/ (https://www.seattletimes.com/business/boeing-aerospace/faa-evaluates-a-potential-design-flaw-on-boeings-737-max-after-lion-air-crash/)
Edit: Apologies, KL27x already posted a link to the main article I was citing.
-
Mmkaay, now FBI with special counsel Miiuulleeerr and DOJ is setting up a investigation to Russian collusion as they suspect Piutin has caused the MCAS software bug. 2 years later no collusion was found and Miiuulleer refuses to release clown report while Dumpf having tea and cakes with Boing CEO..
I like my tinfoil hats, so fair enough. But wait and see. FAA was fasttracking these approvals because someone was poking/pressuring them and or there was some major personal interest or incentive. Maybe Boeing hires retired FAA officials as consultants, and that is enough. Maybe there's more inbreeding and impropriety than that, even. I imagine Boeing is a very important company to our country's military and government.* And somehow many people were actively not doing their jobs and looking the other way.
*Transportation Secretary Elaine Chao even rode in a 737 MAX two days after the latest crash.
I also like my personal tinfoil hats but that was perhaps not the point, but yes wait and see, but perhaps its more like its to much moo money involved (as usually) to send anyone of the "elite" to jail........................except for that little scape goatee engineer somewhere deep down Titanics boiler room?
Secretary Elaine Chao is more of the symptom of US gov mad cow disease rather then the cure. She was plain luckey! :scared:
-
...
The next day, under command of a different crew facing what investigators said was an identical malfunction, the jetliner crashed into the Java Sea killing all 189 aboard.
I can hardly imagine why the crew N1 with such an issues during the flight had not informed the crew N2 on it.
Just watching CNN on new developments on Lion Air case - the pilots were searching in the flight manuals during the dive (from CVR).
-
...
The next day, under command of a different crew facing what investigators said was an identical malfunction, the jetliner crashed into the Java Sea killing all 189 aboard.
I can hardly imagine why the crew N1 with such an issues during the flight had not informed the crew N2 on it.
Just watching CNN on new developments on Lion Air case - the pilots were searching in the flight manuals during the dive (from CVR).
It's very interesting that the Indonesian investigators left out the part about the dead head pilot who knew what he was doing from their report.
Stab runaway is a memory item. That means pilots are supposed to know the procedure, cold.
Evidence is mounting that this system has a design flaw, but the evidence has always been obvious that these crews screwed up.
-
Quotes :
“As the 31-year-old captain tried in vain to find the right procedure in the handbook, the 41-year-old first officer was unable to control the plane, two of the sources said.
It is like a test where there are 100 questions and when the time is up you have only answered 75,” the third source said. “So you panic. It is a time-out condition.”
The Indian-born captain was silent at the end, all three sources said, while the Indonesian first officer said “Allahu Akbar”, or “God is greatest”, a common Arabic phrase in the majority-Muslim country that can be used to express excitement, shock, praise or distress. " :'(
Reuters : Exclusive: Cockpit voice recorder of doomed Lion Air jet depicts pilots' frantic search for fix - sources (https://www.reuters.com/article/us-indonesia-crash-exclusive/exclusive-lion-air-pilots-scoured-handbook-in-minutes-before-crash-sources-idUSKCN1R10FB)
-
There was a frantic search to find out how to disable the trim system because the pilots did not know how to fly the airplane. Stab trim runaway is a memory item. And in the case of lionair, this frantic search was unsuccessful for nearly ten minutes. They were not looking through encyclopedia brittanica here. They would have been looking through a QRH: a laminated, spiral bound book with thumb tabs for common emergencies.
I'm not saying this aircraft did not cause this accident, but this crew's poor performance also caused the accident. Accident chains in aviation almost always have many links.
Reporting on this whole saga has been awful.
-
There was a frantic search to find out how to disable the trim system because the pilots did not know how to fly the airplane.
Blaming the pilots for *any* of these is mean. Blame Boeing, the FAA, revolving doors, complacency, kickbacks, crony capitalism in the US... take your pick
-
...
The next day, under command of a different crew facing what investigators said was an identical malfunction, the jetliner crashed into the Java Sea killing all 189 aboard.
I can hardly imagine why the crew N1 with such an issues during the flight had not informed the crew N2 on it.
Although that behavior sounds completely irresponsible to us, I've heard a couple pilots knowing this company saying that it could likely be explained by cultural factors. N1 had a technical problem and managed to solve it on its own. People there tend to suck it up and move on. Reporting a problem they were not 100% sure was a real problem and not something they themselves caused is kinda against they cultural habits.
As to the 737 MAX, frankly it looks like Boeing went one step too far to extend the 737 line. No clue yet whether they are going to get away with it.
-
Blaming the pilots for *any* of these is mean. Blame Boeing, the FAA, revolving doors, complacency, kickbacks, crony capitalism in the US... take your pick
Perhaps not the pilots of the 610 flight, but ET 302 they should have known already and disable the damn thing in a sec at the first sign.
-
It's very interesting that the Indonesian investigators left out the part about the dead head pilot who knew what he was doing from their report..
Most probably because a) they had not included the entire 24h long CVR transcript into the report.. [the modern CVRs do 24h recording afaik], or b) they listened to the crew N2 talk only..
-
Blaming the pilots for *any* of these is mean. Blame Boeing, the FAA, revolving doors, complacency, kickbacks, crony capitalism in the US... take your pick
Perhaps not the pilots of the 610 flight, but ET 302 they should have known already and disable the damn thing in a sec at the first sign.
I think this post was made with the tongue firmly in cheek. At least I hope it was!
-
Blaming the pilots for *any* of these is mean. Blame Boeing, the FAA, revolving doors, complacency, kickbacks, crony capitalism in the US... take your pick
Perhaps not the pilots of the 610 flight, but ET 302 they should have known already and disable the damn thing in a sec at the first sign.
I think this post was made with the tongue firmly in cheek. At least I hope it was!
Mine or his?
-
Blaming the pilots for *any* of these is mean. Blame Boeing, the FAA, revolving doors, complacency, kickbacks, crony capitalism in the US... take your pick
Perhaps not the pilots of the 610 flight, but ET 302 they should have known already and disable the damn thing in a sec at the first sign.
I think this post was made with the tongue firmly in cheek. At least I hope it was!
Mine or his?
LOL, he means your post. Meaning that you can't be serious saying that the ET302 pilots are to blame, in a sarcastic way
-
Blaming the pilots for *any* of these is mean. Blame Boeing, the FAA, revolving doors, complacency, kickbacks, crony capitalism in the US... take your pick
Perhaps not the pilots of the 610 flight, but ET 302 they should have known already and disable the damn thing in a sec at the first sign.
I think this post was made with the tongue firmly in cheek. At least I hope it was!
Mine or his?
LOL, he means your post. Meaning that you can't be serious saying that the ET302 pilots are to blame, in a sarcastic way
I mean that the ET302 pilots certainly are to blame. The aircraft was flyable. They are not the only ones to blame. There's plenty of blame to go around. I don't care if it is "mean" -- I want pilots who can act decisively in an abnormal situation.
-
I want pilots who can act decisively in an abnormal situation.
Without prior information and instructions, without proper manual, without proper training ?
So how do you want a pilot to act since something that should not happen, happened and they have no clue that some faulty POS hardware has taken over the plane ?
-
When the MCAS system activates, does it result in the trim wheels spinning or does it occur completely silently? Will a nose up trim command override It or does MCAS have the final say? My understanding is that both trim and MCAS act on the same jackscrew that moves the tailplane.
-
When the MCAS system activates, does it result in the trim wheels spinning or does it occur completely silently?
Yes the wheels spin and make noise, and can be stopped by hand, just have to grab them.
Will a nose up trim command override It or does MCAS have the final say?
Yes a nose up trim command overrides, but as soon as you let the button go MCAS starts trimming again in the other direction, nose down. That's why you have to disable MCAS.
My understanding is that both trim and MCAS act on the same jackscrew that moves the tailplane.
Yes, that's right.
-
Both planes crashed in presumably hot climate. Could that have to do with the angle of attack sensors failing?
It is not self evident why misreads from angle of attack sensors are happening. There is something called density altitude that pilots are very conscious of, it effects take off run distance. Addis Ababa Bole airport is at exceptionally high elevation for a main airport - 2334 meters/ 7625 ft. and is in an equatorial climate zone leading to "hot and high" conditions and long take off runs. This probably was only a minor factor, the pilots would for sure keep maximum power in climb for some time after lift-off. At other Airports climb power is dialled back for noise abatement reasons over populated areas.
-
When the MCAS system activates, does it result in the trim wheels spinning or does it occur completely silently? Will a nose up trim command override It or does MCAS have the final say? My understanding is that both trim and MCAS act on the same jackscrew that moves the tailplane.
The trim wheel spins, and it has a "clacker" to make a distinct noise to inform the crew that it is spinning. One way to stop trim changes is to GRAB the wheel and hold it, the override clutches are set such that this doesn't take a lot of force.
There are several systems that use the same trim motor in the center console to adjust the stabilizer. This drives the wheels through a clutch. the wheels then pull a cable loop that operates the jackscrew in the tail.
Jon
-
I want pilots who can act decisively in an abnormal situation.
Without prior information and instructions, without proper manual, without proper training ?
So how do you want a pilot to act since something that should not happen, happened and they have no clue that some faulty POS hardware has taken over the plane ?
In short: yes. I want the pilot to understand "this machine is doing something I do not want, I must stop it." That is how the the QRH is written, that is how the pilots are (supposed to be) trained: turn of automation and get control of the airplane, figure out why that was necessary later. It's just not a huge mental leap to see that the plane is being trimmed hard down against your wishes, and then to stop that. It really doesn't matter the why and or what "should" happen -- things happen on airplanes. MCAS is not the only reason a plane could have runaway trim, and in fact, the section of the emergency checklist isn't called "MCAS doing crazy stuff" it is called "runaway stabilizer trim." You take action and stop it, just as the dead header the other day did.
I have sympathy for this crew, but they screwed up. It happens.
I actually will have more sympathy for them if they were confused about the true state of the aircraft ("maybe it is stalling and Otto is right to want to go down") because of sensor indications than if they knew the plane was malfunctioning and simply failed to stop it. The former is potentially trickier. But we know from the ET302 flight that this went on for like 10 minutes and through several oscillations. We also know this happened in good VMC so there would be plenty of easy visual indications that the plane was at a reasonable attitude, and, barring any major turbulence or acceleration, that means the AOA would not be high, either. That makes the former less likely and the latter much more.
-
When the MCAS system activates, does it result in the trim wheels spinning or does it occur completely silently? Will a nose up trim command override It or does MCAS have the final say? My understanding is that both trim and MCAS act on the same jackscrew that moves the tailplane.
https://youtu.be/AgkmJ1U2M_Q?t=3m26s
-
"runaway stabilizer trim."
More like a hobble away in this case.
-
In short: yes. I want the pilot to understand "this machine is doing something I do not want, I must stop it."
That is what they did as far as they knew the plane BUT
After the two recent crashes, public outrage focused on this particular Boeing decision, and on regulatory agencies in the United States and the European Union who agreed that pilots need not be trained or even alerted to the new software, including the new MCAS override controls.
In other words, as far as pilots knew, the MCAS did not exist.
They were not told the main details about their plane, they had no notion of the mcas so they were in a major disadvantage.
You now sound like that board of inquiry from the movie Sully, why did you not directly go to the nearby airport, simulations have proven you could have made it.
Yeah right if you knew right away what was wrong , how much time you had left and made the right decision in a split second.
I find it harsh to blame a dead crew when they had no information about the cause of the problem in the first place. Add the complete confusion because the plane responds totally different than expected.
That is how the the QRH is written, that is how the pilots are (supposed to be) trained: turn of automation and get control of the airplane, figure out why that was necessary later.
How do you turn something off if no one told you it existed and also not told you how to turn it off, if it can be turned off at all ?
-
How do you turn something off if no one told you it existed and also not told you how to turn it off, if it can be turned off at all ?
They should have known, I mean the pilots of ET 302, because the FAA put out this alert (see the pdf attached) in November 2018 after the Lion flight 610 crash.
-
Lets see what the investigation reveals.
Did they have this AD? They should, but did they?
Which actions did they take and what was the effect?
-
They were not told the main details about their plane, they had no notion of the mcas so they were in a major disadvantage.
Yes, you and others and the media have said this repeatedly. I'm saying something different, as a pilot: it is not relevant. Airplanes at their core, are simple machines. They are objects that are pushed or pulled through the air by engines, and which can change their shape in certain ways to control where they go. That's it. The whole ball of wax. There is a lot of automation in modern aircraft, and pilots, to various degrees, know how it works, or don't. Generally, they know how to use it. They don't know what decisions were made when the software was written, what hidden conditions and failure modes are buried in it. They just don't.
In this case, literally one of the SIMPLEST aspects of the aircraft was out of control: the stabilizer trim. This is controlled, physically, by a prominent and loud wheel in the cockpit, and such wheels are present on just about every aircraft (some trim the elevator, some trim the stabilizer itself). There is nothing mysterious about this.
Better pilots would have stopped this cold.
And as I have said many many times in this thread, that doesn't mean that MCAS is not forked up, or that Boeing didn't screw up. But the pilots still screwed up, and in an obvious way.
You now sound like that board of inquiry from the movie Sully, why did you not directly go to the nearby airport, simulations have proven you could have made it.
Yeah right if you knew right away what was wrong , how much time you had left and made the right decision in a split second.
What is this 10 second nonsense? This plane oscillated more than 20 times over 10 minutes. This is nothing like the Sully movie.
And by the way, I would love to know what Sullenberger would think of this accident. I have a strong suspicion that in pilot's lounges around the world, 737 drivers are mad at Boeing, but also wondering how those crews could have screwed the pooch so badly.
I find it harsh to blame a dead crew when they had no information about the cause of the problem in the first place. Add the complete confusion because the plane responds totally different than expected.
It is harsh. Airplanes are dangerous and judge mistakes harshly. That is the nature of aviation.
How do you turn something off if no one told you it existed and also not told you how to turn it off, if it can be turned off at all ?
Jumpin' Jesus on a pogo stick! They didn't have to turn off the MCAS! They had to turn off the trim system, which of course, they knew about. It's a motor that drives one the basic flight control surfaces of the machine.
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=682905)
-
If the FAA put out an alert then does it become the pilots responsibility to track FAA alerts or is it the airlines responsibilty to inform the pilots of FAA alerts and provide additional training. Ultimately it is the manufacturers responsibility to inform the airlines and the pilots. Looks like a lack of due diligence on someones part and I don't think it's down to the pilots.
-
Lets see what the investigation reveals.
Did they have this AD? They should, but did they?
Which actions did they take and what was the effect?
If they didn't, it really is the pilots fault (both of them) for not reading required material to maintain their certifications.
Additionally, it would be the Ethiopian airlines fault, as they claimed all their 737 Max pilots received additional training on the MCAS, even before the black boxes were found.
Never mind that this was such current news so much that the general public was aware of it. Airline pilots even more so!
-
Yes, you and others and the media have said this repeatedly. I'm saying something different, as a pilot: it is not relevant. Airplanes at their core, are simple machines. They are objects that are pushed or pulled through the air by engines, and which can change their shape in certain ways to control where they go. That's it. The whole ball of wax. There is a lot of automation in modern aircraft, and pilots, to various degrees, know how it works, or don't. Generally, they know how to use it. They don't know what decisions were made when the software was written, what hidden conditions and failure modes are buried in it. They just don't.
In this case, literally one of the SIMPLEST aspects of the aircraft was out of control: the stabilizer trim. This is controlled, physically, by a prominent and loud wheel in the cockpit, and such wheels are present on just about every aircraft (some trim the elevator, some trim the stabilizer itself). There is nothing mysterious about this.
Better pilots would have stopped this cold.
Well if you are an experienced 737 pilot with thousands of flight hours you probably know best.
-
Yes, you and others and the media have said this repeatedly. I'm saying something different, as a pilot: it is not relevant. Airplanes at their core, are simple machines. They are objects that are pushed or pulled through the air by engines, and which can change their shape in certain ways to control where they go. That's it. The whole ball of wax. There is a lot of automation in modern aircraft, and pilots, to various degrees, know how it works, or don't. Generally, they know how to use it. They don't know what decisions were made when the software was written, what hidden conditions and failure modes are buried in it. They just don't.
In this case, literally one of the SIMPLEST aspects of the aircraft was out of control: the stabilizer trim. This is controlled, physically, by a prominent and loud wheel in the cockpit, and such wheels are present on just about every aircraft (some trim the elevator, some trim the stabilizer itself). There is nothing mysterious about this.
Better pilots would have stopped this cold.
Well if you are an experienced 737 pilot with thousands of flight hours you probably know best.
That's literally not an argument.
As I've stated upthread, I am a pilot, not an airline pilot. I fly much simpler aircraft. Yet even in those aircraft there are sophisticated autopilots and I know how to disable them.
I'll tell you one thing I probably have in common with those guys: I don't want to die in an airplane crash. To that end, I think quite a bit about what I'd do in a given situation, whether I'd be up to it or not. I, of course, don't know. But to take a ship into the air, one should at least try to approach the question honestly. Most, but not all, pilots read a LOT about accidents. They study the mistakes of others. In the process, you come across some where you're pretty sure you wouldn't make that mistake, others where you see yeah, I would be susceptible to that. In the end, of course, until you're tested, you just don't know. But you still think about it. You still analyze, try to predict, try to mentally prepare. And to the best of my non-737 driver ability to predict, I think most competent pilots would have flown through these upsets. Maybe scared, maybe angry, but they would have kept control. That opinion is worth just as much as yours, no more, no less.
-
And to the best of my non-737 driver ability to predict, I think most competent pilots would have flown through these upsets. Maybe scared, maybe angry, but they would have kept control. That opinion is worth just as much as yours, no more, no less.
I think if you put the world's 100 best 737 commercial pilots in this situation, without any knowledge of MCAS, a significant percentage of them would have failed. The most important bit to me, is if Boeing has disclosed the specifications of the MCAS system to its customers, this could have dropped to practically zero (in this exact scenario, anyway... it could have been much worse). Sure, some better pilots would have shut off the stab trim before the final super malfunction from the double-triple hit of MCAS. Some much worse pilots would have, as well. But it was probably avoidable in the first place.
What is this 10 second nonsense? This plane oscillated more than 20 times over 10 minutes. This is nothing like the Sully movie.
And during that 10 minutes, the MCAS fired 21 times. So during that 10 minutes, the plane was bucking violently more than half that time. That makes it a bit more difficult to use the emergency manual. Every time the thing went off, the pilot had seconds to correct the plane, rather than reading a manual. No matter how great it is organzed, it will be hard to use under these conditions.
This is what I consider a fact: The stab cutout switches were never designed to handle this kind of event. A system that can erroneously adjust the trim to 50% of a full nose dive per activation should need to be automatically or easily deactivated from the main control column or yoke. This MCAS could theoretically erroneously fire at ANY altitude, as far as we know. It may not even be recoverable at all if it happened during takeoff or landing.
Consider the FO took control, having just lived through 21 of these events. And the very first time it happened under his control (he got a double whammy, apparently), the plane was not recoverable even from a mile up.
-
They were not told the main details about their plane, they had no notion of the mcas so they were in a major disadvantage.
Yes, you and others and the media have said this repeatedly. I'm saying something different, as a pilot: it is not relevant.
I'm not a pilot, but I understand enough to see the validity of the above statement. The symptom of a stabilizer going crazy is all that matters in determining the action required. The cause is pretty much irrelevant when you are trying to control the aircraft and you already have a procedure in place to deal with the problem.
-
This is what I consider a fact: The stab cutout switches were never designed to handle this kind of event.
Then why were they fitted? (To me, the answer is really obvious.)
-
^ to me the it is obvious that shutting off the autopilot was made more easy and intuitive than cutting out those stab trim switches. The dual stab trim switches are there for a reason.... just in case the first part fails. And in the original 737 design, the only thing automatically adjusting the trim would have been an autopilot thing, making small but persistent adjustments, not a full on nose dive at over 1G, losing significant altitude that takes time to regain.
If the MCAS were disclosed, cutting out the stab trim switches would not be a secondary action in this instance of violent downward trim. You do not have time to even do that if this error happened at low enough altitude and it would be very difficult to take your eyes off the ground to flip switches on the ceiling if it happened out of the blue at low altitude and you are in an unexpected free fall.
If it's the second action on a paper in flight emergency reference manual, it works better if you have time to refer to the manual before you are dead. Esp if you are a seasoned 737 pilot who has learned all the important bits of the 737, and then you are told the MAX is exactly the same.
-
this guy is a programmer and a (cessna) pilot and seems to think the core problem is, that what should have been a brand new aircraft design was being sold as a 737 still.
https://drive.google.com/file/d/1249KS8xtIDKb5SxgpeFI6AD-PSC6nFA5/view?fbclid=IwAR0CXP2xVmFT2pSGMmx519uFmRw7jMs9uq5FnrumIqT34KcS8j5of5bTWa8 (https://drive.google.com/file/d/1249KS8xtIDKb5SxgpeFI6AD-PSC6nFA5/view?fbclid=IwAR0CXP2xVmFT2pSGMmx519uFmRw7jMs9uq5FnrumIqT34KcS8j5of5bTWa8)
And as a result of this corporate sleight of hand, it has a very unstable airframe, which is patched by an added software system that the 737 never had before, and safety is signed off by someone in the aircraft manufacturer's employ, with a huge conflict of interest.
Added bonus, it seems like the auto control software was written by a siloed off group that has no practical experience with flying planes, and certainly no understanding of the fragility of mechanical sensors.
-
If the MCAS were disclosed...
You are still not getting the point.
The symptom was runaway stabilizer. There is a predetermined set of actions to be executed in such a situation - and, from what I have seen, these are memory items - NO MANUAL LOOKUP REQUIRED.
You could list a dozen causes for a runaway stabilizer problem - one of which may be MCAS - but exactly which one does not matter when it comes to taking remedial action.
-
And in the original 737 design, the only thing automatically adjusting the trim would have been an autopilot thing, making small but persistent adjustments, not a full on nose dive at over 1G, losing significant altitude that takes time to regain.
Pretty sure that's not true. There are two things that, without MCAS, are *supposed* to cause the stab trim to move: the pilots trim switches and the autopilot. But if their is a fault in either of those, or the wiring between them and the motors, or if there is a mechanical fault in the system, then the system can go haywire. (The reason it has that grasp and hold item in the checklist is in part because there are mechanical failure modes where unit can move on its own, and the pilots can stop it.) Again, the procedure outlined in the FCOM/QRH is to stop the trim from moving, and it just doesn't ask or even mention anything about the cause.
If the MCAS were disclosed, cutting out the stab trim switches would not be a secondary action in this instance of violent downward trim. You do not have time to even do that if this error happened at low enough altitude and it would be very difficult to take your eyes off the ground to flip switches on the ceiling if it happened out of the blue at low altitude and you are in an unexpected free fall.
I think basically the first part is true: if the pilots were aware of MCAS, they would have been more likely to act to shut out the trim motors. However, the ET pilots did know this (or could have) and didn't, so there is also a training requirement. The second part about time is still dubious to me. MCAS actually us unlikely to activate near the ground as it cannot operate when flaps are out. So you'd have to be near the ground due to something weird happening already for MCAS to be a factor there.
Also, the switches are on a lower console, not that it matters,
If it's the second action on a paper in flight emergency reference manual, it works better if you have time to refer to the manual before you are dead. Esp if you are a seasoned 737 pilot who has learned all the important bits of the 737, and then you are told the MAX is exactly the same.
Pretty sure the stab runaway procedure is *supposed* to be a memory item, meaning the pilots should know it. But the book exists because nobody remembers everything in an emergency. But again, this is not an ordinary book. It is designed to be used in an emergency, and has large type, thumb indexed sections, red to outline the emergency stuff. The idea is that while one person is handling the aircraft, the other can grab this and get critical information out of it. Whether this is true in practice, I don't know. But it is definitely intended that pilots can quickly access emergency procedures.
-
You are still not getting the point.
I get it.
- and, from what I have seen, these are memory items - NO MANUAL LOOKUP REQUIRED.
I'll concede this, even. Djaco seems to agree on this.
But a 737 pilot with 5,000 hours of training on a 737 and countless more hours of simulation, they expect certain things. This was not expected. Do you appreciate what 2.5 degrees of stab trim means (per activation)? See the vid of the MAX doing a stunt takeoff. 2.5 degrees is half the total trim, and it can erroneously retrigger, giing it unlimited authority. This is not something expected. And it happened at a low enough altitude to be a real gut check.
If this happened while a plane happened to be banking in a tight enough turn at low enough altitude in approach maneuvers, it might not even be recoverable. Your first automatic response after flying 737 forever would be to cut out autopilot and correct manually. Then you get hit with the multiple erroneous activations, and it is too late to fix that, at all.
*Djacobow: yeah, I don't know at what altitude you extend/retract the flaps, but apparently even a mile up does not give a lot of time. 20-25 seconds to impact, maybe the last 10 to 15 could be too late to correct.
-
But a 737 pilot with 5,000 hours of training on a 737 and countless more hours of simulation, they expect certain things. This was not expected.
I think this is where our arguments diverge - the identification of the problem. As I understand it, one of the purposes of simulation time is to train and keep pilots "up to speed" in identifying and resolving abnormal situations.
Real life doesn't always play nice, presenting you with familiar, practiced scenarios - but, rather, will add its own twists. This is why I am not going to pursue the point any further and I will see what comes from the investigation.
-
I want pilots who can act decisively in an abnormal situation.
Without prior information and instructions, without proper manual, without proper training ?
So how do you want a pilot to act since something that should not happen, happened and they have no clue that some faulty POS hardware has taken over the plane ?
In short: yes. I want the pilot to understand "this machine is doing something I do not want, I must stop it." That is how the the QRH is written, that is how the pilots are (supposed to be) trained: turn of automation and get control of the airplane, figure out why that was necessary later. It's just not a huge mental leap to see that the plane is being trimmed hard down against your wishes, and then to stop that. It really doesn't matter the why and or what "should" happen -- things happen on airplanes. MCAS is not the only reason a plane could have runaway trim, and in fact, the section of the emergency checklist isn't called "MCAS doing crazy stuff" it is called "runaway stabilizer trim." You take action and stop it, just as the dead header the other day did.
I have sympathy for this crew, but they screwed up. It happens.
I mean that the ET302 pilots certainly are to blame. The aircraft was flyable. They are not the only ones to blame. There's plenty of blame to go around. I don't care if it is "mean" -- I want pilots who can act decisively in an abnormal situation.
I would wait to draw such conclusions. Its guaranteed what pilots have said regarding 737MAX (is that a new STM32F model?) will be one of the hot points when this debacle mangles in the courts. From NASA pilot safety database: https://asrs.arc.nasa.gov/search/database.html
The airplane’s nose can tilt down suddenly during takeoff, pilots aren’t being adequately trained on the autopilot system, and the operations manual is “criminally insufficient.” These are the complaints of US pilots in incident reports involving Boeing’s 737 Max 8 jetliner, the same model that was involved in two deadly crashes in recent months.
Another pilot said it was “unconscionable that a manufacturer, the FAA, and the airlines would have pilots flying an airplane without adequately training, or even providing available resources and sufficient documentation to understand the highly complex systems that differentiate this aircraft from prior models.”
That same pilot added, “I am left to wonder: what else don’t I know? The Flight Manual is inadequate and almost criminally insufficient. All airlines that operate the MAX must insist that Boeing incorporate ALL systems in their manuals.”
After the Lion Air Flight 610 crash, Seattle Times has published an article that Boeing did not inform companies or pilots that they even installed the system. This means that pilots had no knowledge about MCAS and its processes.
-
In the words of Mike Tyson, "Everyone has a plan, until they get punched in the face."
-
Prediction: The 737 Max will not fly again.
There’s a precisely zero percent chance of this outcome.
I would not be so sure.
The reputation of the name "737 Max" is already pretty much destroyed.
They might do some small alterations and rename the model to for instance 737 Plus or something like that, in that case mtdoc's prediction has become reality.
There is literally zero, null, nada, zilch chance that it won’t take to the skies again (with the same name). Though the crashes are terrible, the cause is fairly simple and will be simple to fix. As others have explained to you already, many aircraft models had early issues, but later went on to be reliable, safe workhorses.
This isn’t a comparatively cheap product like a smartphone where a complete recall costs “just” a few billion dollars. This was $2-3B in development alone, and then each aircraft costs $121 million, and they delivered 350 units so far. A permanent recall would thus cost a total of $45.4 billion. It’s not gonna happen, especially since the fix will be very inexpensive.
-
Even after disabling stab trim and turning the wheel manually to narrowly avoid the first impact, the pilot would have probably stalled the fully loaded plane in tbe process, believing it to be able to lift and handle like a regular 737.
This is the exact scenario where properly functioning MCAS is necessary to make 737 pilots qualified to fly the MAX.
If Boeing had let this cat out of the bag, pilots would have needed to learn how to manually fly a 737 MAX, and it would have required another 9 months to a year for certification. They could not even acknowledge this difference to their customers. There's no way a 737 pilot would have known to jam the trim a whole 2.5 degrees when the stick shaker went off.
-
Even after disabling stab trim and turning the wheel manually to narrowly avoid the firat impact, the pilot would have probably stalled the fully loaded plane in tbe process, believing it to be able to lift and handle like a regular 737.
What?!? The whole issue with the engines is that the MAX has too much lift, not too little. MCAS’s job is to nudge the nose back down, not up.
-
What?!? The whole issue with the engines is that the MAX has too much lift, not too little. MCAS’s job is to nudge the nose back down, not up.
The reason for this is because the MAX will easily enter an unrecoverable stall if you are at a high angle of attack, which would not happen with the previous versions. You would be using a high angle of attack when pulling up from an unexpected dive at low altitude. And you would have to deactivate MCAS to do this. The pilot would be manually flying a plane that handles very differently and stalls much easier than the plane he was certified on. The new plane was slipped under the same certification because of this MCAS system.
-
Even after disabling stab trim and turning the wheel manually to narrowly avoid the firat impact, the pilot would have probably stalled the fully loaded plane in tbe process, believing it to be able to lift and handle like a regular 737.
What?!? The whole issue with the engines is that the MAX has too much lift, not too little. MCAS’s job is to nudge the nose back down, not up.
You focused on the wrong aspect of the word "lift". It was not the magnitude of the lift force that was intended in the cited statement, but the aspect of "lift and handle" (perhaps better stated as just "handle") "like a regular 737".
The point being that when thrust is added in the MAX, it has a (significantly) greater upward turn moment than that of earlier models of 737. This will cause more pitch up than a pilot used to the older models would expect ... ie. it does not handle "like a regular 737".
-
^No not just that. According to Djacobow, the aerodynamics of the engines, themselves, increase the lift as the AOA increases. So as the AOA increases, the AOA increases itself. In order to utilize the same high angle of attack in the MAX, the pilot would have to know how the plane handles to "ride the edge." They would have to preemptively trim down (a huge amount!) to maintain that high AOA in a way that it doesn't run away from them. I imagine it is a bit like countersteering in a car where the back end can break loose. If you don't expect it, you are probably going to spin around and go over the edge of the cliff.
-
You guys are going in circles. Some of you need to stop assuming pilots are idiots if not properly trained on the aircraft. Stop saying stupid things like pilots automatically will stall the plane if the system isn't on. They still have basic flying skills that apply to all planes to fall back on. Arguments about what constitutes certification doesn't make the pilots incompetent and unable to react to the consistent and controllable effects of engine thrust, even on manual control.
Clearly Boeing expected the plane to be flyable with the automatic trim system disabled, or the procedure wouldn't be in the manual and the stab cutout switches wouldn't exist.
-
^LOL okey doke.
Of course manually flying the plane is better than the plane in permadive. But controlling the plane in a high AOA would have been extremely difficult for someone who has trained on the old plane and handed this one that is supposed to be no different.
The original plane was designed from the start to be stable. The change in engine made it unstable at high AOA. Pilot can't be expected to use a high AOA for the first time in an emergency situation and magically "feel" the angle getting away with adrenaline coursing (and lol if you think they are going to be determine this by sensor readings in real time), and knowing to respond so quickly and drastically to maintain control of the plane.
-
The reason for this is because the MAX will easily enter an unrecoverable stall if you are at a high angle of attack, which would not happen with the previous versions.
Stall characteristic of MAX is the same as NG. What's different - increased pitch up effect of the LEAP-1B engines due to their placement (forward & up). Pitch-up increases AOA which may lead to stall.
The new plane was slipped under the same certification because of this MCAS system.
MCAS system was introduced to slip MAX under "minor modification of existing plane" certification. Boeing was cutting corners on self-certification (allowed by FAA) because of competition from Airbus. 737 NG - licensed pilots were trained for MAX on iPads during 1-hour session. No simulator session required :palm: This is criminal negligence from Boeing, regulators and airlines: https://www.aviationcv.com/aviation-blog/2019/shocking-facts-boeing-737max-crash (https://www.aviationcv.com/aviation-blog/2019/shocking-facts-boeing-737max-crash)
-
Some of you need to stop assuming pilots are idiots if not properly trained on the aircraft.
+1 , this :-+
Some sound so convinced that like they're actually have been in the cockpit watching the whole scenery. :palm:
-
Stall characteristics of MAX is the same as NG. What's different - increased pitch up effect of the LEAP-1B engines, their placement (forward & up). Pitch-up increases AOA which may lead to stall.
But additionally, at high angle of attack, the engines themselves aerodynamically produce lift and drag. At high angle of attack, the plane isn't flying nose first. The vector of travel is at an angle to the attitude of the plane. And larger engines further forward is like an "air brake" giving the effect of the plane wanting to flip/rotate. This is very pronounced. We know this because of the degree of trim movement that MCAS needed to make.
In the original plane, as designed, this high AOA would be stable. On the MAX the problem is not inadvertently nosing the plane up due to thrust. Otherwise, MCAS would adjust the trim a tiny bit according to the amount of thrust. It's the problem of what happens to the plane once it is at a high angle of attack which MCAS addresses. At this point the plane is unstable and wants to spin in the air, tail under nose. That's the direction of force that the engine placement creates in this attitude.
Stall characteristics of MAX is the same as NG.
If it handled just like the NG, there would be no need for MCAS. The normal response would be sufficient.
-
At high angle of attack, the plane isn't flying nose first.
Right. :-DD
-
What I mean is the plane isn't flying like an arrow. A high AOA would be a situation where the nose is tilted up and the back end of the fuselage passes through a lower point in space than the nose of the fuselage.
When the plane is puling up hard from a dive, it doesn't reach level flight the instant the plane's fuselage is horizontal to the ground. The vector of the plane will still be such that the plane is losing some altitude at this point.
This is what high AOA means, don't it?
-
At high angle of attack, the plane isn't flying nose first.
What? I think it sums it up pretty nicely. Angle of attack of 0° means the plane is flying perfectly nose first. As in the plane is pointing in the same direction as its air speed velocity.
-
^I don't know if Berni is backing me up or piling on. But I fully agree with his statement.
I'm not a pilot and I'm not trying to school anyone. I'm just using common sense. Just because you're not a pilot doesn't mean you have to take words like AOA and treat them like a made-up thing in Star Trek.
-
At high angle of attack, the plane isn't flying nose first.
What? I think it sums it up pretty nicely. Angle of attack of 0° means the plane is flying perfectly nose first. As in the plane is pointing in the same direction as its air speed velocity.
No, it doesn't. You're confusing angle of attack with pitch. In a straight and level cruise, you're still going to need a positive angle of attack to counter the force of gravity.
Angle of attack is the difference between the chord of the wing and the actual direction of travel. Note that flaps, when deployed, change the shape of the wing which changes the chord of the wing which changes the angle of attack relative to the pitch of the plane. Similarly, spoiler devices on the wing can spoil the lift, which doesn't actually change the chord, but does change the angle of attack because it affects the direction of flight.
-
^Ok. Take everywhere I said AOA and change it to pitch.
So "pitch" is the angle of the plane relative to the vector of the plane's velocity, not an angle in relation to the earth, right? And for simplicity, I'm not worried about wind.
The engines being fixed to the plane, w/e you call it, this is the problem I'm referring to. As the angle of the plane increase upwards in relation to its vector, there is a point where the MAX will be unstable and will quickly go out of whack beyond recovery in a positive feedback loop (at least compared with the original version). This is what seems obvious to me from what we have been told and including what Djacobow has previously explained a few pages back.
-
Everyone here is being overly specific. Let's start by quoting wikipedia.
In aerodynamics, angle of attack specifies the angle between the chord line of the wing of a fixed-wing aircraft and the vector representing the relative motion between the aircraft and the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be definable, so an alternate reference line is simply defined. Often, the chord line of the root of the wing is chosen as the reference line. Another choice is to use a horizontal line on the fuselage as the reference line (and also as the longitudinal axis).
OK, so:
1. Angle between the longitudinal axis of the aircraft and earth (irrespective of direction of travel): is called Pitch (so KL27x, the answer to your last question is "No, pitch *is* related to the earth")
2. Angle between the longitudinal axis of the aircraft and the velocity of the aircraft through the air: is called AOA (assuming we choice the "another choice" in the Wikipedia definition); and needn't be positive in straight and level flight (especially at high speed)
3. Angle between root chord of the wing and velocity of the aircraft through the air: is also called AOA (assuming the chord line definition is used); and this particular definition I could believe Nusa's claim that this must always be positive in straight and level flight, maybe.
In short, let's stop arguing over an ill-defined term like AOA. A wing designer probably has definition 3 in mind, while a pilot maybe probably has definition 2 in mind.
-
Ah it is a confusion with pitch. No, pitch and AOA are two different things.
Pitch is the front to back angle of the plane relative to horizontal on earth. It makes up the absolute rotation angle along with Roll (angle left to right relative to horizontal) and Yaw (rotation around the planes vertical axis relative to the earths north pole).
This is much like mixing Yaw and Heading. Heading is also relative to the north pole, but its the direction the plane is moving. Wind causes the difference between the two as crosswind essentially makes the plane fly slightly sideways relative to the ground below (This is seen nicely in heavy crosswind landings)
AOA is the angle of the difference between your Pitch Roll Yaw of your plane and the direction of the wind outside (Tho usually you only want AOA to be offset in the Pitch direction). Its essentially what angle the air is hitting the wings. You want a few degrees of AOA for the wings to produce lots of lift, but if the AOA gets too high the wings go into a so called aerodynamic stall where the lift drops sharply, the drag sharply raises and heavy turbulence develops around the wing. This is very bad because no lift means you fall out of the sky and because the wings are now ineffective its very difficult to control the plane to get it pointing forwards again so that the AOA reduces and you get lift again.
-
I'm pretty happy with those explanations. I think my previous posts are fairly ok, then.
Regardless if perfectly horizontal flight means the AOA must be positive, that is irrelevant. When pulling up out of a nose dive to avoid crashing the plane into the ocean, one would expect the plane to be put into a high AOA. And this is where the MCAS would kick in to prevent the 737-trained pilot from losing the plane to a stall.
So in the case of having to shut off MCAS because the plane it put into a nose dive with an imminent date with the earth, the pilot would then be putting the 737 MAX into a high AOA and facing the dangerous potential of a stall. Crash into the ocean at 600mph, or fall into the ocean at 200mph. Dead is dead.
-
The thing is that this MCAS system would take a while to adjust the trim so low that the plane would nose dive into the ground.
The pilots would have seen the big trim wheels moving as MCAS is trimming pitch down. The wheels also make a mechanical noise as they spin on purpose to make them more noticeable. All they would have to do is flick a switch to disable automatic trim, manually trim it back to level and then continue flying as normal.
But the fact that the pilots are not properly trained about the new MCAS and its possible failure modes, likely means that the pilots are suddenly suspecting other failures and reacting according to those, the high stress situation making them too focused on certain things that they would not notice the trim wheel oddity. There are many many things that can go wrong on a plane, troubleshooting a system you don't even know exists on such short notice as you are heading for the ground is not easy.
-
New update. This man is probably the best subject-matter-expert reporter available for interpreting the actual facts released from various sources:
https://www.youtube.com/watch?v=9Ts_AjU89Qk (https://www.youtube.com/watch?v=9Ts_AjU89Qk)
-
^8:23 for insight over MCAS and the interesting perspective that a third pilot might bring.
There are many many things that can go wrong on a plane, troubleshooting a system you don't even know exists on such short notice as you are heading for the ground is not easy.
Exactly. And even though the problem went on for 10 minutes in the Jakarta case, think how near these "single" spaced out malfunctions would put the plane to death that entire time. In the fully loaded plane, you would lose altitude much more quickly than regaining it. It only took the one double malfunction in rapid succession to end it all. The captain took back control but it was not in time. You know he wasn't taking a nap. He was right there, trying to save everyone's life.
The thing is that this MCAS system would take a while to adjust the trim so low that the plane would nose dive into the ground.
Did you see the altitude graph? I imagine everyone on the plane lost their lunch. These changes don't appear to be gradual. This guy ^ uses the words "absolutely terrifying." "Startle factor." No matter how big the wheel or how loud it clicks, it appears to be quite responsive. See the vid someone posted of the vertical takeoff, how fast it can level out. Just because it is normally steered like the Titanic doesn't mean it can't change vector in a hurry. I imagine the MCAS system would be moving the elevator as fast as possible. The runaway trim which pilots have been trained and done simulation with is never going to move the elevator that much or that fast, lest someone spill their drink. Only 5 degree change needed for full nose dive, per the Seattle Times article, and the MCAS does 2.5 degrees per firing. How much of that elevator range did the test pilot in the stunt takeoff use? Was that even full elevator?
I refuse to believe that 2 out of 2 pilots can get a job flying a hundred million dollar plane with 200 souls on board without being halfway competent.
*You can also see in this video the location of the AOA sensor is on the sides of the plane near the nose. Thus, the AOA, as measured by these vanes, is the angle of the plane vs the air it is passing through. It is only measuring the angle of the "wings" by virtue that the wings are attached to the fuselage. So I don't get the hubbub over my usage of AOA. I didn't think modern commerical jets rotate their wings to adjust AOA. They may have some control surfaces to change the curvature of the top of the wing to change the amount of lift. And there are flaps. But the wings are pretty fairly well fixed in place, otherwise.
Tooki: the pilot in this video states what you did, as to the reason for MCAS. That it is there because the position of the engine produces substantial nose up force. But we know by virtue of how it works, this is not correct IMO. It kicks in based on AOA sensor. It only kicks in after the nose has gone up. It is not there to make the plane handle like a 737. With the MAX, the pilot can get the nose up by increasing thrust. This isn't counteracted by the elevator under normal AOA. It's only when the AOA gets extreme that it kicks in. So as long as the AOA is not nearing the danger zone, yeah, the nose goes up under hard acceleration. No magic prevents this from happening. The magic pixies kick in if this goes too far out of the normal range. IOW, the MAX can't necessarily pull up with greater force than the NG. The elevator can do that just fine; the engines need not do this at all. What this means is the MAX loses control.... if not before, at least more suddenly... than the NG does.
-
Why did none of the pilots at least grab and stop the trim wheel? I still don't get it. The damn thing was spinning under their noses. They knew what that wheel spinning meant, didn't they? Three minutes is a long time, it's not a sec, yet they couldn't connect the dots. Poor guys. It's so sad.
-
Three minutes is a long time...
In a confusing, high stress, life and death situation, 3 minutes will pass very, very quickly.
-
The thing is that this MCAS system would take a while to adjust the trim so low that the plane would nose dive into the ground.
Did you see the altitude graph? I imagine everyone on the plane lost their lunch. These changes don't appear to be gradual. No matter how big the wheel or how loud it clicks, it appears to be quite responsive. See the vid someone posted of the vertical takeoff, how fast it can level out. Just because it is normally steered like the Titanic so no one spills their drink doesn't mean it can't change vector in a hurry. I imagine the MCAS system would be moving the elevator as fast as possible. Only 5 degree change needed for full nose dive, per the Seattle Times article. How much of that did the test pilot in the stunt takeoff use? Was that even full elevator?
Well yes you can certainly make negative G or pull over 2G in a big airliner if you try.
But the quick maneuvers are done using the control surfaces moved by powerful hydraulic pistons, these are the ones tied to the pilots control column and can certainly move very fast. But things like trim are different, here the entire wiglet on the tail moves. This is moved via a motor turning a worm gear, all this gearing down gives it plenty of oomph while turning very slowly, as in normal use it is never needed to turn quickly. This is what MCAS is moving via trim.
The problem is that the entire wiglet is much bigger than the small flap part at the end of it. This small flap is what is moved quickly and responsively by hydraulics. If the whole wiglet is tilted up a little bit then you can just tilt down the flap to counteract it, but once the wiglet tilts more it can produce more force than the little flap can at full deflection. At this point no matter what the pilot does on the control stick he can't get the nose back up (Well apart from rolling the plane on its back, but then you have a uncontrolled pitch up and its certainly not something you are supposed to do in an airliner, especially if you ask the passengers).
The two fighting forces of the wiglet and its flap also produce more drag, slowing the plane down, making it even harder to keep altitude.
Keep in mind that the pilot can keep it perfectly level while the trim is being turned down by simply pulling back on his controls more and more. But eventually he hits the end of his control range and that's when the plane starts to plummet. (Tho if the plane was warning him of a stall he might not pull up since that's the opposite of what you are supposed to do if approaching a real stall)
-
https://www.rt.com/news/454275-indonesia-crash-third-pilot/ (https://www.rt.com/news/454275-indonesia-crash-third-pilot/)
Off-duty pilot reportedly saved Boeing 737 MAX from crashing day before disaster
Extract: An extra pilot, who hitched a ride on a Lion Air Boeing 737 MAX a day before its crash in October, saved it during an emergency strikingly similar to the one that proved fatal, Bloomberg reports.
The new airliner plunged into the Java Sea killing all 189 people on board apparently due to a malfunction in an anti-stall system which pushed the nose of the aircraft down.
A day before the crash the same aircraft experienced a similar problem but was saved by an off-duty pilot who realized what was happening and instructed the crew on how to stop the system from affecting the flight, the agency said.
I wonder if the MCAS software interprets 'rapidly declining altitude' as 'must be still stalled, try more pitch down' ?
Also, with all the spoken warnings to pilots in modern cockpits, you'd think someone would add some spoken messages from MCAS, to let pilots know why the 'safety system' was killing them.
Though given the attitude inherent in implementing something like MCAS (rather than just warning the pilots), such a message would probably be something unhelpful like "I hate you, die die dieeeee!"
This is why I refuse to own a car with computerized engine and drive systems. Well, ONE reason why.
-
Berni, I wonder where you are getting this information that is not in the news? Are you interested in aviation or do you have personal experience?
Google "737 winglet" and it says this is the little vertical thing at the tips of the wings. The elevators appear to me as one piece on either side of the tail. As far as I know, the elevator is the most powerful control surface for rapidly changing the attitude/AOA of the plane under normal flight. And the same elevator used by MCAS or by autopilot trim is also used by the pilots for manual control.
GeorgeoftheJungle, in my understanding, everyone who is talking about the trim wheel slowly clicking away until the snoozing pilot realizes his plane is facing the ground is not on the right planet. This kind of incident might have surprised the pilots the first time, but not the 22nd time. If the wheel makes a clicking sound, maybe watch a video of a Marlin fisher and the sound the reel makes when the fish is pulling away at 50 knots. When this happened, the pilots didn't need to hear the clicks to suspect something was wrong. Their seats falling out from under them and their lunch pushing into their esophagus provided all the notice they needed. If that didn't work, I'm sure the 200 screams would have woke the dead. This is not a gradual trim adjustment or course change. It's a last ditch massive response for when the S has already HTF, and all the drinks have already been spilled.
-
Google "737 winglet" and it says this is the little vertical thing at the tips of the wings.
I think he did mean horizontal stabilizers. Indeed it would be good that we do not re-invent naming of airplane parts & systems
https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/ (https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/)
-
There are control surfaces on the wings for banking. There are flaps on the wings for increasing lift and drag during takeoff and landing. There are sliding surfaces on the top rear of the wing for changing the amount of lift.
Don't let the words "trim" or "stabilizer" fool you. The elevators are the most powerful control for changing the plane's vector. If you want to do a loop de loop or a rapid nose dive, you use the elevators.
-
Yes the technical term for that part of the tail is the elevator but i wanted to stick to generic terms. So winglet as in "a small wing shaped thing" rather than those little upwards curving things on the end of wings, but yeah those are indeed called winglets (Unintended name clash).
I do have some interest in aviation and work at a company that makes avionics, but i am not a pilot, so don't take my words as fact.
Was mainly trying to explain why trim does not cause the plane to suddenly nose dive out of the blue within a second, but rather its a slow gradual thing that makes the plane more and more nose heavy as time goes on until at some point it becomes impossible to keep it up by normal control column input.
-
There are control surfaces on the wings for banking. There are flaps on the wings for increasing lift and drag during takeoff and landing. There are sliding surfaces on the top rear of the wing for changing the amount of lift.
Don't let the words "trim" or "stabilizer" fool you. The elevators are the most powerful control for changing the plane's vector. If you want to do a loop de loop or a rapid nose dive, you use the elevators.
If that were true, we wouldn't be in this situation. In fact, the elevators are the second-most powerful control for that purpose, having less surface area than the horizontal stabilizer itself. Part of the reason the stabilizer jackscrew has that much travel is that it's intended to serve as a backup system for a jammed or inoperative elevator. In normal operation, the two systems work together.
-
GeorgeoftheJungle, in my understanding, everyone who is talking about the trim wheel slowly clicking away until the snoozing pilot realizes his plane is facing the ground is not on the right planet. This kind of incident might have surprised the pilots the first time, but not the 22nd time. If the wheel makes a clicking sound, maybe watch a video of a Marlin fisher and the sound the reel makes when the fish is pulling away at 50 knots. When this happened, the pilots didn't need to hear the clicks to suspect something was wrong. Their seats falling out from under them and their lunch pushing into their esophagus provided all the notice they needed. If that didn't work, I'm sure the 200 screams would have woke the dead. This is not a gradual trim adjustment or course change. It's a last ditch massive response for when the S has already HTF, and all the drinks have already been spilled.
You're seeing the plane's trying to kill you, every time you release the nose up button in the yoke the trim wheel next to you starts spinning again in reverse, for gods sake at least grab the damn wheel to stop it going nose down again. Why not?
-
Yes the technical term for that part of the tail is the elevator but i wanted to stick to generic terms.
In this discussion we better use terms that do not lead to confusion :)
(https://www.grc.nasa.gov/www/k-12/airplane/Images/airplane.jpg)
-
^ Indeed. Those ARE the generic terms. If people don't know them, they better learn them to talk in this thread.
-
What?!? The whole issue with the engines is that the MAX has too much lift, not too little. MCAS’s job is to nudge the nose back down, not up.
The reason for this is because the MAX will easily enter an unrecoverable stall if you are at a high angle of attack, which would not happen with the previous versions. You would be using a high angle of attack when pulling up from an unexpected dive at low altitude. And you would have to deactivate MCAS to do this. The pilot would be manually flying a plane that handles very differently and stalls much easier than the plane he was certified on. The new plane was slipped under the same certification because of this MCAS system.
Yup, I already knew and fully understood this. Hence why I was like "wtf" at your comment.
You focused on the wrong aspect of the word "lift". It was not the magnitude of the lift force that was intended in the cited statement, but the aspect of "lift and handle" (perhaps better stated as just "handle") "like a regular 737".
The point being that when thrust is added in the MAX, it has a (significantly) greater upward turn moment than that of earlier models of 737. This will cause more pitch up than a pilot used to the older models would expect ... ie. it does not handle "like a regular 737".
I understand this. But I didn't "focus on the wrong aspect", actually: at the moment when I actually clicked "Quote", it only said "lift", not "lift and handle" — that was edited in later. (I didn't notice it sneak into the quoted text.)
-
Yup, I already knew and fully understood this. Hence why I was like "wtf" at your comment.
This is clear as mud. Not the transparent kind.
I get wordy and confusing, at times. But this pretty much sums up what I meant:
The MAX can't necessarily pull up in a tighter radius or G force than the original 737. Yeah, the moment of inertia from the engine will push the nose up more than the original. But the elevator can do that just fine as much as you would ever need; the engines need not do this at all. It seems evident to me that MCAS is needed because the MAX is not as controllable at this high AOA. Even after you cut the engine back, the aerodynamic lift and drag of the larger, higher, farther forward engines in this high AOA presentation make the plane want to nose up (more).
So I sorta disagree with Brumby and the popular explanation of this in the news. Yeah, the plane wants to nose up during engine acceleration, but MCAS is not going to kick in until there's near stall conditions. It is expected that 100% of pilots will adapt to the way the plane flies and handles without ever activating MCAS. Else Boeing would be even dumber and more brazen than anyone here has even thought to hand out planes they expect pilots to inadvertently stall. No. MCAS is there for the unlikely event a pilot needs to intentionally utilize an extremely high AOA.
-
My piloting experience is only with RC model planes so I'm not going to claim expertise on the matter, but if I were in the cockpit of an airliner and the plane trimmed itself fully nose down and started plunging to earth I can't imagine having a first reaction other than grabbing the trim wheel and cranking it back up. Clinging to it holding the trim within the authority of the elevator to keep the plane in level flight buys as much time as needed to assess the situation. I mean I realize the machine usually knows what it's doing but if the plane is in a steep dive it seems obvious something is wrong.
-
^Agree, this sounds logical. And I hate to take over the thread with my machine gun posts. I'm hating myself.
But as far as we know, this has maybe happened on 3 occasions, and in 2 of them the plane went down. So either these 4 pilots had no common sense, or this is not as simple as it sounds.
Maybe later, we will find out this has happened a hundred times, and only 2 sets of pilots went down the wrong path. Or maybe it really was only the 3 occasions and 4 out of the first 6 pilots (7 if you include the 3rd NP on the plane that properly cut the stab trim) just happened to be out of the norm.
-
At high angle of attack, the plane isn't flying nose first.
Right. :-DD
I would not have put it this way, but it is essentially correct. I mean, it is always correct in the sense that when the angle of attack is not 0.0, the aircraft is not flying, relative to the wind, in the same direction it's pointing. At high AOA, this is a noticeable difference. Again, this may seem absurd to non-pilots, but this is just how planes are. The direction they are going relative to space, relative to air, and relative to which way they are pointed can all be different, and usual are.
-
Stall characteristics of MAX is the same as NG. What's different - increased pitch up effect of the LEAP-1B engines, their placement (forward & up). Pitch-up increases AOA which may lead to stall.
But additionally, at high angle of attack, the engines themselves aerodynamically produce lift and drag. At high angle of attack, the plane isn't flying nose first. The vector of travel is at an angle to the attitude of the plane. And larger engines further forward is like an "air brake" giving the effect of the plane wanting to flip/rotate. This is very pronounced. We know this because of the degree of trim movement that MCAS needed to make.
Let's be careful to distinguish between stall characteristics, and the aerodynamics of the airplane at high AOA, but near a stall.
I don't think anyone has discussed stall characteristics of the 737 on this thread. I don't know what they are, and I suspect precious few have experienced them, mostly Boeing test pilots. The whole "system" is built around not getting there.
This whole discussion concerns avoiding getting into stall territory, and from what I've read, MCAS was designed to deal with the fact that as you get near a stall, the airplane starts to push further towards the stall on its own, and this tendency is either not present in the non-MAX versions, or it is weaker.
-
^Agree, this sounds logical. And I hate to take over the thread with my machine gun posts. I'm hating myself.
But as far as we know, this has maybe happened on 3 occasions, and in 2 of them the plane went down. So either these 4 pilots had no common sense, or this is not as simple as it sounds.
Maybe later, we will find out this has happened a hundred times, and only 2 sets of pilots went down the wrong path. Or maybe it really was only the 3 occasions and 4 out of the first 6 pilots (7 if you include the 3rd NP on the plane that properly cut the stab trim) just happened to be out of the norm.
Something else we agree with. I think pilots should have handled this situation pretty readily, and yet they did not. That could be for any number of reasons, and we just don't know what they are yet. But I think that gets to my overarching point which is that the world seems ready to throw Boeing management in prison for pushing an unsafe airplane, and I think the reality is much more complicated. (In fact, I'm surprised at the rush to judgment regarding the very *idea* of this airplane being fundamentally flawed.) We obviously need to find out why the MCAS system "went haywire", but we *also* need to find out why pilots aren't following the emergency procedures they were supposedly trained to follow by memory.
-
^Agree, this sounds logical. And I hate to take over the thread with my machine gun posts. I'm hating myself.
Another way we agree. I am not having any fun in this thread and probably need to step away from the keyboard. :-)
-
Disturbing facts ...
Reuters : Ethiopia crash captain did not train on airline's MAX simulator: source (https://www.reuters.com/article/us-ethiopia-airplane-simulator-exclusive/ethiopia-crash-captain-did-not-train-on-airlines-max-simulator-source-idUSKCN1R20WD)
“Boeing did not send manuals on MCAS,”
“Actually we know more about the MCAS system from the media than from Boeing.”
“It is still very disturbing to us that Boeing did not disclose MCAS to the operators and pilots,”
-
Jumpin' Jesus on a pogo stick! They didn't have to turn off the MCAS! They had to turn off the trim system, which of course, they knew about.
The normal failure mode they seem to be trained for is a continuous run away though. The mach system they knew about could not produce such a failure mode AFAICS (though it can be dangerous in its own right on a malfunction at low altitude). Stuck switches or shorts could never produce such a failure mode ... it would be a one in a billion type failure mode without MCAS.
As I said, more a hobble away than a runaway.
-
The normal failure mode they seem to be trained for is a continuous run away though. The mach system they knew about could not produce such a failure mode AFAICS (though it can be dangerous in its own right on a malfunction at low altitude). Stuck switches or shorts could never produce such a failure mode ... it would be a one in a billion type failure mode without MCAS.
You're right. The word "continuous" in the instructions is not exactly consistent with this scenario, and I guess that could have kept pilots from following it. However, though this problem was intermittent, when the trim motor ran, it ran for a rather long time - 10 seconds, and I believe 2.5 degrees of stab movement per go; as I understand it, that's an awful for a 737.
-
The AOA DISAGREE dash LED is optional, Boeing just announced it's making it mandatory. Airbus includes it for free.
I wonder how much it cost, this aviation-spec LED, some wire and a connector. It must be $10,000's of dollars on a $120M aircraft.
Missing a lousy LED on the instrument panel is beyond pathetic :palm: caught up in politics and marketing.
I have to agree:
"Boeing's 'Optional' Safety Equipment on the 737 Max is a Monument to Corporate Greed" (https://www.esquire.com/news-politics/politics/a26894297/boeing-737-max-optional-safety-equipment-pay-extra)
-
https://www.ft.com/content/d726faea-4b36-11e9-bbc9-6917dce3dc62 (https://www.ft.com/content/d726faea-4b36-11e9-bbc9-6917dce3dc62)
Boeing will install an extra safety alarm in the cockpits of all its 737 Max aircraft after intense criticism in the wake of two fatal crashes.
The US aerospace group has decided to include a warning light in new 737 Max planes and to retrofit all existing ones, according to a person familiar with the situation.
The alarm will tell pilots if two “angle of attack” sensors — which indicate the angle of a plane’s nose — disagree, a sign that one is not working.
-
I mean, it is always correct in the sense that when the angle of attack is not 0.0, the aircraft is not flying, relative to the wind, in the same direction it's pointing.
Right. Boeing does good job explaining AOA:
(http://www.boeing.com/commercial/aeromagazine/aero_12/images/attack_whatisaoa.jpg)
http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html
(http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html)
-
This new 737 model was built as and designated as a 737 in order to save certification time and training costs for airlines that were the customers of the planes.
At the end of the day, the 737 MAX should NOT have been a 737. The basic 737 airframe is not compatible with the engine size they needed to put on the plane. and when they did it anyway the airframe became unstable, in that approaching a stall the plane becomes more likely to go into a stall. this is nothing like the behaviour of any 737 in the nearly 50 years 737s have been in the sky.
And now it appears that the massive control system hack put in place to try and neutralise the massive mechanical problem caused by using engines that were too large ended up being "downplayed" so that the 737 certification could stand. "downplayed" to the point that it doesn't even tell you when it's operating! (and massive incompetence in the actual execution of the control system - the active control system only even looks at one vane to make decisions that can kill everyone on board if the vane is faulty!)
Yes in a perfect world a non-panicked pilot is sometimes able to work out what is wrong with a crashing 737 max, because we know a few did... It seems they are especially able to work it out if they have had training on how this new 737 isn't like every other 737 they ever flew... but in 2 cases now, the pilots didn't... so.... it's kind of obvious that whatever was done was nowhere near enough. Just by the results we have seen in the world.
So all the armchair pilots sitting here saying "but they should have adjusted the trim back" - yeah I'm sure you're a cool and in control genius, and you would have magically worked out what exactly was going on with the whole visual field full of dials and controls while the plane was randomly just pulling your control column away from you and falling out of the sky while you tried to fly it, and saved the day. But so far two flight crews managed to not save the day and hundreds of people are dead. So it seems that unfortunately real commercial pilots aren't as good as you...
This is 100% the result of a corporation using weakened regulatory systems to cut costs at the expense of human lives.
-
The AOA DISAGREE dash LED is optional, Boeing just announced it's making it mandatory. Airbus includes it for free.
I wonder how much it cost, this aviation-spec LED, some wire and a connector. It must be $10,000's of dollars on a $120M aircraft.
Missing a lousy LED on the instrument panel is beyond pathetic :palm: caught up in politics and marketing.
I have to agree:
"Boeing's 'Optional' Safety Equipment on the 737 Max is a Monument to Corporate Greed" (https://www.esquire.com/news-politics/politics/a26894297/boeing-737-max-optional-safety-equipment-pay-extra)
LED?? No. It’s an on-screen indicator on one of the color LCDs, according to a video I saw.
-
So all the armchair pilots sitting here saying "but they should have adjusted the trim back" - yeah I'm sure you're a cool and in control genius, and you would have magically worked out what exactly was going on with the whole visual field full of dials and controls while the plane was randomly just pulling your control column away from you and falling out of the sky while you tried to fly it, and saved the day. But so far two flight crews managed to not save the day and hundreds of people are dead. So it seems that unfortunately real commercial pilots aren't as good as you...
This is 100% the result of a corporation using weakened regulatory systems to cut costs at the expense of human lives.
But that isn't what it was doing. It didn't "pull the control column" anywhere, it spun the trim wheels fully nose down, an action that is impossible to not notice happening or recognize. When you say "visual field full of dials and controls" it makes it sound like an aircraft instrument panel is a sea of random controls that the crew has no idea what they do, while in reality any competent pilot knows precisely what all of them do and where they all are from memory. A pilot needs to be able to deal with situations like this, whether due to a design fault with the aircraft, a mechanical failure or some external factor. The fact that these crews apparently didn't do that suggests a degree of incompetence. I'm not going to judge them entirely until we have all the details but to assert that this is "100%" anything at this point is quite frankly bullshit, we don't know what happened with certainty yet, but assuming things played out the way early evidence suggests, then the crew gets at least a portion of the blame here. I will remind you that there are at least a couple actual certified pilots in this thread, not just a bunch of armchair goobers who haven't got a clue.
There have been a LOT more incidents throughout aviation history where flight crews not only failed to save the day, but actively caused the accident through their own error or neglect. The fact that two may have failed to deal with the same situation here does not necessarily absolve them from blame.
-
Is it just me, or does anyone else think that there's something immoral about Boeing designating functionality that is for the sole purpose of increased flight safety (such as the "disagree light") as "optional" and charging extra for it? And thus allowing corporate airline customers to opt-out of paying for it to be implemented in their aircraft? Comfort and operational economy options, sure. But items that can only be classified as "safety-related" and designed to notify when the rest of the aircraft isn't performing up to its paid-for specifications at the potential expense of all the lives aboard? Apparently, Boeing has a corporate policy which holds that not all passengers deserve equal levels of flight safety.
On each flight, there are, like, 200-odd passengers who assume when they buy their ticket that the aircraft they are flying in is as safe as the aircraft industry can reasonably make it. Airlines who fly equipment that is not "as safe as the industry can reasonably make it" due to missing safety options that could have been purchased, but were not, should be forced to make that information public. Letting consumers vote with their feet about what airlines they want to fly based on who's "cheaped out" on their safety is likely the only way to put a stop to what I consider outrageous, money-chiseling, negligent behaviour.
-
At the end of the day, the 737 MAX should NOT have been a 737.
Firstly, that statement suggests to me you do not understand the type rating system at all. I'm not a pilot, but I have been following some of the ecology...
There are many variants of the 737 and just because a pilot has been "type rated" for one model does not mean they can hop into the cockpit of any 737. Where the changes are significant enough - and these do exist in the 737 line - pilots must go through the full "type rating" process, which impacts both pilots and airlines. However, there are several models where the differences are minor and a pilot rated for a previous model may only need to undergo "difference training" to be qualified to fly the new version. This is easy to achieve and represents minimal impact to an airline and their pilots. This is the reason why any aircraft will not have too many things change, to make sure the differences are small enough so that "difference training" is all that is needed.
There's nothing wrong with the MAX-8 being presented as a 737. What may be the case (which could be part of the fall-out of these incidents) is that it should have been classed as a new type. In that case, pilots will need to do type rating - and that is going to impact everyone.
-
LED?? No. It’s an on-screen indicator on one of the color LCDs, according to a video I saw.
I thought it is located on the center forward panel? Air Canada and WestJet had already ordered the aircraft with the indicator light but I don't have pics.
Why would Boeing charge $ for some text annunciator on an LCD? Putting the word AOA DISAGREE on an LCD. They charge money for that!?! :wtf:
Southwest Airlines is adding an AoA "indicator" (gauge) on the primary flight display. I'm not sure that is useful- what happens when there is a sensor disagreement, to not create confusion.
-
There have been a LOT more incidents throughout aviation history where flight crews not only failed to save the day, but actively caused the accident through their own error or neglect. The fact that two may have failed to deal with the same situation here does not necessarily absolve them from blame.
what happened is we have had two crashes one after the other with new planes of the exact same model, killing hundreds of people.... Even if those two crews weren't the best pilots in the world, I expect that they had managed to not kill everyone while flying plenty of other 737s before. Both crews came unstuck on this new model.
I think it's safe to say that the the differences of this particular plane from any previous ones, and the way those differences were handled, was a massive error of judgement that has cost hundreds of lives.
And when i say "error of judgement" I mean "conspiracy of criminal negligence that should see the people involved in the highest levels of managing the project imprisoned for the rest of their lives, and Boeing out of business if it can't afford to do either a full recall of their not-fit-for-purpose planes. Or at very least, complete some kind of retrospective "new plane" process on this model for all the planes of this type currently out there."
There's a particular concern with the allegation that their software bodge was baked into the system and hidden in a way that it was not obvious it even existed, letalone obvious it was operating.... And the allegation that it only used the mechanical vane sensor on one side of the plane to make string of repeated decisions that ended up killing everyone on board, and didn't even have the ability to cross check the plane's dual sensors for sensor faults.
-
There's nothing wrong with the MAX-8 being presented as a 737. What may be the case (which could be part of the fall-out of these incidents) is that it should have been classed as a new type. In that case, pilots will need to do type rating - and that is going to impact everyone.
Thanks for the terminology tip.
But it's more than just pilots doing the training to be allowed to fly it.
They should have to prove the that this new type (of which over a hundred planes just like the 2 crashed ones are out there in the world by now) is even fundamentally ok to have pilots trained to operate it.
-
All the dirt that had swiped underneath the carpet, are starting to pop out one by one.
CNN : Pilots transitioned to 737 Max 8 with self-administered online course (https://edition.cnn.com/2019/03/22/us/max-8-boeing-self-administered-courses-lion-air-ethiopian-airlines-intl/index.html)
Quotes :
Pilots of Southwest Airlines and American Airlines took courses -- lasting between 56 minutes and three hours -- that highlighted differences between the Max 8 and older 737s, but did not explain the new maneuvering characteristics augmentation system, know as MCAS, the spokesmen said.
"MCAS was installed in the aircraft and Boeing didn't disclose that to the pilots," said Trevino, while adding that Southwest pilots are experienced with 737s.
"This is ridiculous," said Captain Dennis Tajer, a representative of the Allied Pilots Association, which represents 15,000 American Airlines pilots. "If you're going to have equipment on the airplane that we didn't know about, and we're going to be responsible for battling it if it fails, then we need to have hands-on experience."
-
The basic 737 airframe is not compatible with the engine size they needed to put on the plane. and when they did it anyway the airframe became unstable, in that approaching a stall the plane becomes more likely to go into a stall. this is nothing like the behaviour of any 737 in the nearly 50 years 737s have been in the sky.
Yes, and if true, this is why the 737 Max will not (or should not) fly again. All the focus in this thread on armchair piloting and engineering bodges seem to be ignoring this fundamental and overwhelming design flaw. A different or better bodge wil not fix the underlying problem which if the plane is continued to be allowed to fly will eventually result in more deaths.
But I do not want to underestimate the corporate power, greed and regulatory capture at work here so maybe they will be stupid enough to allow it to fly again after the new bodges are in place.... ::)
-
There have been a LOT more incidents throughout aviation history where flight crews not only failed to save the day, but actively caused the accident through their own error or neglect. The fact that two may have failed to deal with the same situation here does not necessarily absolve them from blame.
The blame here has already been established: 737M8 and M9 are grounded worldwide. Simple as that.
No it has not been established, and it's not as simple as that. The planes have been grounded until the investigation determines what happened and what if any corrective actions must be taken. There may well be a problem with the aircraft but grounding them by no means establishes blame.
-
Yes, and if true, this is why the 737 Max will not (or should not) fly again. All the focus in this thread on armchair piloting and engineering bodges seem to be ignoring this fundamental and overwhelming design flaw. A different or better bodge wil not fix the underlying problem which if the plane is continued to be allowed to fly will eventually result in more deaths.
But I do not want to underestimate the corporate power, greed and regulatory capture at work here so maybe they will be stupid enough to allow it to fly again after the new bodges are in place.... ::)
It will absolutely fly again, I would wager a substantial amount of money on that fact. It will probably go on to have a good safety record, just as many other planes have in the past. There have been numerous cases of design flaws on new aircraft causing deadly crashes, aircraft type groundings and investigation, and in not one single one of these cases did the type not fly again. Won't happen here either, it's silly to even suggest it as a possibility. These incidents will certainly cost Boeing sales but the problem will be solved and the planes will be back in the air.
Absolute most drastic case, MCAS will be removed and pilots will require re-training to deal with the different handling characteristics of the max. Some people here seem to fail to comprehend this, it is not unstable or badly mannered, it simply handles differently than the 737 classic and thus requires the MCAS in order for it to be flown by pilots certified on the 737 classic. The upward pitch when thrust is increased is a characteristic of ALL airliners with engines slung under the wings. The difference here being the max exhibits this to a greater degree.
-
Oh yeah, de facto it has been established, on official paper it just takes more time. Otherwise find me other pilot error produced accident in which a global fleet was grounded. Or a pilot induced accident in which the justice department did subpoena Boeing and the FAA, or ....
Unless you know something that the rest of us don't, you don't know whether it was pilot induced, or caused by a flaw in the aircraft, or caused by a combination of these, or something else entirely. It's sensible to ground the aircraft because there is reasonable suspicion of a problem with the design but that is not the same as establishing blame. The investigation is underway, it will be months before blame is established, and it will probably turn out to be a cascade of events that all worked together to cause the accidents.
When a person is suspected of a crime they are arrested and charged, if it is a serious crime they will be detained, but that does not establish blame. They are innocent until proven guilty in a court of law, in other words the court establishes blame, and only after the crime is investigated and the evidence examined. Sadly many people do not understand this and jump the gun trying to be an armchair judge and jury all rolled into one.
-
Absolute most drastic case, MCAS will be removed and pilots will require re-training to deal with the different handling characteristics of the max. Some people here seem to fail to comprehend this, it is not unstable or badly mannered, it simply handles differently than the 737 classic and thus requires the MCAS in order for it to be flown by pilots certified on the 737 classic. The upward pitch when thrust is increased is a characteristic of ALL airliners with engines slung under the wings. The difference here being the max exhibits this to a greater degree.
My reading of the fundamental issue that the hidden software bodge was designed to overcome, is the 737 MAX8 not only exhibits regular upward pitch when thrust is increased, but far worse - it also exhibits more upward pitch increase the more the upward pitch is increased.... ie the upward pitch on the 737 MAX8 has a positive feedback element that is not present on other 737s (or pretty much any other commercial plane ever) and the plane is aerodynamically unstable for that reason.
-
.... and the plane is aerodynamically unstable for that reason.
How wrong can you be?
IF it WAS aerodynamically unstable, then how come there have been thousands of successful flights?
Such illogical statements don't add to the discussion, but make a mockery of it.
-
.... and the plane is aerodynamically unstable for that reason.
How wrong can you be?
IF it WAS aerodynamically unstable, then how come there have been thousands of successful flights?
......
Most planes get aerodynamically unstable at to high an AoA - that is what the stall problem is about. The problem with the 737max can be that high high thrust the critical AoA can be lower than normal. So adding thrust can be even worse.
With a working MACS (e.g. no sensor failure) the system seems to work OK and they even got through with only minimal extra training.
I am a little skeptic about the option to only give only better instructions to the pilots on how to disable the MACS. They would ad least need quite some extra (e.g. simulator) training on how to fly with the MACS deactivated.
My guess is Boing will have to update the software and give some training / info to the pilots, so that the system is less likely to fail (e.g. use both sensors, limit the power) and the pilots know better how to handle a possible upset. So it's more like a question on how long the planes stay at ground. If thing go well maybe before the summer season, would be nice to be ready before the winter season.
-
How wrong can you be?
IF it WAS aerodynamically unstable, then how come there have been thousands of successful flights?
Such illogical statements don't add to the discussion, but make a mockery of it.
I dunno... how wrong can you be? It looks like you are trying to make it a competition or something. those 3 sentences have an amazing hit rate for wrongness. I'm not sure I'll be able to keep up but hey, I'll give it a red hot go:
Now. In absence of you going and reading up on control theory or even just feedback in systems I'll break what I said down into smaller steps for you, and try to explain the terminology so you can keep up with the discussion and stop resorting to derailing the discussion and making a mockery of it by acting abusively.
So, what I'm talking about with this new plane, is there's a problematic state variable in a flying plane "system". This state variable is either "pitch" or "angle of attack" (whichever it happens to be, the particular one is unimportant for this discussion.. possibly it's also tied to a second state variable, which I'd expect might be "thrust", maybe there's even more associated variables.. but I'm leaving that out for the sake of simplicity.. only one contains the feedback mechanism when feedback starts, so it's the critical one here)
1) This state variable, for some range of values, has a positive feedback loop. That is - for a range of values of the state variable, with no control operating on that variable, that state variable will increase without bound (well, until hitting a natural limit of the system, stalling the plane, and killing everyone onboard)
2) The positive feedback effect on that state variable is literally a case of instability for that state value. Other 737s in flight do not have this positive feedback on this state variable and therefore this state variable isn't unstable for other 737s in flight.
3) Instability in any one (or more) state variables of a system literally defines that system to be unstable. that's, like, the definition of an unstable system... Now, other planes that don't have positive feedback in any state variables don't meet this definition. This plane does, though.
4) Now, we need to take a moment and back off from the definition above and realise that a system being "unstable" doesn't necessarily mean the whole system just oscillates chaotically in the full range of all its state variables and is impossible to control in any way from the instant it starts in motion (that would be your worst case for instability in a system)
5) In the case of this plane, instability most likely makes it harder to control the plane when the system hits a state variable value that brings in positive feedback... Which is exactly what the software bodge is there to try and avoid in this plane, but seems it did that in a terrible way. The very existence of this software bodge tells us explicitly that Boeing knew that not only is the flying plane unstable in this variable, it's bad enough that the instability needs to be countered (or masked) You don't bodge software like that up and put it inside a life critical control system just because you're bored on a rainy weekend, you know.
PS, I'm not an expert on aerodymanics here, but it's my understanding that a lot of fighter planes are deliberately aerodynamically unstable in different ways because it allows them to do fast manoeuvres they couldn't do if they were stable... BUT fighter planes have ejector seats for that reason, and aren't full of passengers for that reason (OK, and probably other reasons...)
Anyway, here's some fun discussion on fighter plane stability I googled for you. Enjoy. But please be very careful not to sign in and abuse the people on this stack exchange about how they are stupid and not contributing to a discussion on fighter plane instability and control, because if fighter planes were unstable how could they ever fly, and thousands of fighter plane flights happen every day.
https://aviation.stackexchange.com/questions/8049/are-fighter-jets-designed-to-be-so-inherently-unstable-that-a-human-cant-fly-on (https://aviation.stackexchange.com/questions/8049/are-fighter-jets-designed-to-be-so-inherently-unstable-that-a-human-cant-fly-on)
-
5) In the case of this plane, instability most likely makes it harder to control the plane when the system hits a state variable value that brings in positive feedback... Which is exactly what the software bodge is there to try and avoid in this plane, but seems it did that in a terrible way.
Thank you, well explained. Chain of events for many may seem like: high thrust of engines pitched plane up, MCAS activated and decided to kill everybody by trimming horizontal stabilizers into deadly nosedive. Definitely it was not that simple. Problem could be that positive feedback pitch-up is non-intuitive for pilots that are not trained for such. They may see MCAS actions (trim) as "this f**ing plane does not let me gain altitude as fast as I am used to". If they counteract MCAS trim using other control surfaces - it will make things worse. How else we can explain stabilizer trim jackscrew to be in full nosedive position while plane was gaining altitude & overspeeding till last moments? It may not be faulty AOA instrument. It could be so that pilots were successfully operating older 737 planes closer to critical AOA than treshold is set for MCAS. Suddenly MCAS decided that what they do is not safe, started to trim, pilots did not know what the plane is doing, was trying to compensate using wrong controls/approach. When pilots counteract stabilizer trim during speed increase at high thrust, sooner rather than later trimmed for dive stabilizer will be more effective than all the other controls combined that are in the pilots hands (joystick).
To me it seems like "pilot not trained for particular (type of the) plane", like this airplane crash (https://en.wikipedia.org/wiki/Lokomotiv_Yaroslavl_plane_crash). They were taking off with parking brake activated...
-
of which over a hundred planes just like the 2 crashed ones are out there in the world by now
376 delivered to customers as of last month.
The blame here has already been established: 737M8 and M9 are grounded worldwide. Simple as that.
Such things have happened before. The DC-10 fleet was grounded by the FAA (they even pulled it's type rating) early in its career for a series of accidents. Yet it went on to a successful passenger career. A bunch of them are still flying in cargo service (most are now called MD-10's after a glass cockpit upgrade that allows them to share a type rating with the MD-11). Fex-ed operates most of them.
The 737 classic had rudder failures earlier in its career that caused fatal crashes and control problems. Took them years to figure that one out and years more before they were all retrofited. There were so many in the sky that I don't think anyone even considered grounding the entire fleet. It would have crippled airlines around the world.
And that's just off the top of my head. The other guys are right, the 737-MAX is going to fly again, and probably fairly soon. I'd put money on it.
I dunno... how wrong can you be? It looks like you are trying to make it a competition or something.
You might be winning this competition.
PS, I'm not an expert on aerodymanics here
That's real obvious. Yet you're acting like an authority with your conclusions.
-
PS, I'm not an expert on aerodymanics here
That's real obvious. Yet you're acting like an authority with your conclusions.
What he tells about positive feedback is not conclusion, but well known fact:
The engines were both larger and relocated slightly up and forward from the previous NG CFM56-7 engines to accomodate their larger diameter. This new location and size of the nacelle causes it to produce lift at high AoA; as the nacelle is ahead of the CofG this causes a pitch-up effect which could in turn further increase the AoA and send the aircraft closer towards the stall.
All this adds to pitch-up effect from engine thrust.
http://www.b737.org.uk/mcas.htm (http://www.b737.org.uk/mcas.htm)
-
PS, I'm not an expert on aerodymanics here
That's real obvious. Yet you're acting like an authority with your conclusions.
What he tells about positive feedback is not conclusion, but well known fact:
The engines were both larger and relocated slightly up and forward from the previous NG CFM56-7 engines to accomodate their larger diameter. This new location and size of the nacelle causes it to produce lift at high AoA; as the nacelle is ahead of the CofG this causes a pitch-up effect which could in turn further increase the AoA and send the aircraft closer towards the stall.
All this adds to pitch-up effect from engine thrust.
http://www.b737.org.uk/mcas.htm (http://www.b737.org.uk/mcas.htm)
This is not a software analysis that's simulated to guaranteed failure in 0.01 seconds. There's real physics and time and pilot opportunities to correct involved. What an automatic system can do automatically, a pilot can do manually, if necessary. In any case, the engine placement is NOT the direct cause of these accidents. Focus on what actually went wrong.
-
This is not a software analysis that's simulated to guaranteed failure in 0.01 seconds. There's real physics and time and pilot opportunities to correct involved. What an automatic system can do automatically, a pilot can do manually, if necessary. In any case, the engine placement is NOT the direct cause of these accidents. Focus on what actually went wrong.
Even Boeing admitted that most likely source of crash is (possibly inferior) MCAS system which were introduced for which exactly reason? - Engine placement. So, please, don't.... Also you have no authority to tell what we shall focus on or not. On the other hand I agree to you that most likely they will solve potential issues w/o scrapping MAX or reverting it to NG engines.
-
My reading of the fundamental issue that the hidden software bodge was designed to overcome, is the 737 MAX8 not only exhibits regular upward pitch when thrust is increased, but far worse - it also exhibits more upward pitch increase the more the upward pitch is increased.... ie the upward pitch on the 737 MAX8 has a positive feedback element that is not present on other 737s (or pretty much any other commercial plane ever) and the plane is aerodynamically unstable for that reason.
The thing is, having an inherently aerodynamically unstable airframe and using software to make it what I'll call "apparently stable" to the pilots is a completely valid design approach. (Think of the Segway scooter, which is only possible because of software.)
So, operating under the assumption that MCAS is what failed, my take on this is that Boeing screwed the pooch in the implementation of MCAS.
1. It should not have been allowed to make such drastic corrections. The maximum correction per intervention event is already far more than they'd originally planned — and had submitted to the FAA — but the real issue is that if a pilot overrides a full-scale MCAS intervention, even by the tiniest amount, MCAS will re-trigger soon and can apply full-scale correction again, resulting in MCAS being able to push the elevators all the way nose-down. This is many, many, many times more correction than it had been described as being capable of, and I'm fairly confident this was not by design. (It should only be able to apply a certain amount of total cumulative correction, rather than only being limited within a single intervention, but unlimited in the number of interventions it can make.)
2. The other issue, arguably the bigger one, is that MCAS seems to use only the input from a single AOA sensor, which is insanity IMHO, especially given that the plane already has more than one such sensor! I can't imagine any reason why you wouldn't use the inputs from hardware that's already in place. IIRC, the MAX has two AOA sensors, which of course means that in the case of disagreement, you can't immediately know which one is wrong. So I totally agree with the others who've said that simply, there should be three, so that you can do a "best 2 of 3" analysis and thus have a reading with a high level of confidence.
Both of these flaws have to be in place at the same time for the crashes to happen in the way we suspect as of right now. Fixing either one would have prevented the crashes. And both are comparatively easy to fix, so if I were Boeing, I'd fix both.
-
As I said before, I am not sure this plane will fly again with the same name.
It has a bad reputation and people don't want to fly in it anymore.
Today the first airliner cancelled their order of 49 MAX planes .
Sorry only dutch but translated: the reason for the cancelation is that their customers have lost all trust in this plane and the airliner would like to order a different type of plane.
https://www.nu.nl/economie/5804268/vliegmaatschappij-garuda-indonesia-annuleert-bestelling-49-boeings.html (https://www.nu.nl/economie/5804268/vliegmaatschappij-garuda-indonesia-annuleert-bestelling-49-boeings.html)
-
As I said before, I am not sure this plane will fly again with the same name.
It has a bad reputation and people don't want to fly in it anymore.
You've said it before, and I'll say again that there's a zero percent chance this will happen.
The DC10, for example, had some design flaws that caused a few crashes early on. It had a similar image problem. But the flaws were identified and fixed, and the DC10 went on to become one of the most successful airliners of its era. Consumers absolutely did not dwell on its early reputation.
The fact is, most people don't even give a second's thought to what aircraft type they're flying on. They assume (correctly) that the airlines have a vested interest in not having their planes crash, and thus that they're airworthy.
-
That's real obvious. Yet you're acting like an authority with your conclusions.
Most of the conclusions I'm talking about are already discussed by people who do have expertise..
I'm not the person who invented the idea that the basic 737 shape is incompatible with the huge engines they bolted on to the max8, and that the hacking on of engines that are too big caused the plane to become unstable.
I'm not the one who first explained how the way this particular plane was allowed into the market and the skies seems to be shady as all hell due to the above 2 points and the apparently secret/hidden fix that was bolted into the plane's software system to try and patch it but apparently spoken about very little.
that post I made that you quoted half a line of out of context was just dealing with someone who wanted to have a go about things and didn't even know the fundamentals of system stability.
my main point in this thread is dealing with armchair pilots who think that despite ALL WE HEAR about how irregular this project was, and how different the plane physically is compared to the 737 version it's pretending to be the same as, that just because one pilot is known to have been able to save one of these planes with the fault from crashing once, that it must mean that the other 2 flight crews whose planes crashed, killing everyone on board, must have just been incompetent and the planes are fine.
Maybe they will fly these planes again, because sure, rich people hate losing money, and I bet there's a bunch of rich people directing lackeys right now to make sure they lose the least money possible over this... And sure, maybe it is just going to be a control system update...
Whatever they do, I just want a serious investigation into the suitability of whatever their final fixed version of the plane is, because the first declaration of suitability for that plane was an absolute pile of bullshit. So more of the same process is not going to cut it.. And really, moving forward, airplane manufacturers should not be self-certifying planes if stuff like this can happen.
And hopefully they'll also come to the conclusion that's its a very new and specific type of plane so people get trained properly on how not to die while flying it...
The only conclusion of my own that I've brought up here, really, is that it is looking a bit like this project contained a high level conspiracy to avoid corporate responsibility and save money, at the cost of human safety and now lives... So a thorough investigation into the decisions made by the key high-level people responsible for this project should to be a big priority, and if found to be a criminal conspiracy or even the slightest hit of unethical behaviour, they should be going to prison for consecutive life sentences for each person that died on those planes.. And I'll argue that all day, given what we've heard about the way the project certification was managed, the way new plane introduction and training was managed, and how different this plane apparently is to the plane it's certified to be..
-
he thing is, having an inherently aerodynamically unstable airframe and using software to make it what I'll call "apparently stable" to the pilots is a completely valid design approach. (Think of the Segway scooter, which is only possible because of software.)
I absolutely agree... some forms of instability can definitely be patched with control systems, and the segway is a great example.... I would never claim otherwise.. but if you're going to do that, the system has to be fit for purpose...
And when we are talking about a plane where a critical error kills everyone on board, that system has to be robust and it has to be incapable of killing people no matter what you throw at it.
And when you're talking about a massive complex thing like a plane where pilots have to be able to override the system if it's going wrong, well you also have to be frank and open about what the plane is, how it actually works, and how it might be different from other planes you've ttold people it's the same thing as..
Both of these flaws have to be in place at the same time for the crashes to happen in the way we suspect as of right now. Fixing either one would have prevented the crashes. And both are comparatively easy to fix, so if I were Boeing, I'd fix both.
you'd also have to fix the documentation and the training and probably the plane type, but yes I agree, if the MCAS could be made to not fall down in a screaming heap and kill everyone on board, it could possibly be a suitable fix for the planes physical instability, as long as people piloting the plane were fully aware of what it was doing, why it was there, and had some experience flying the plane without it enabled.
Also, whoever let the plane design out with such obvious holes in the design needs to be seriously investigated (like, did anyone even consider a basic system level FMEA on this thing? that should have pointed out the issue with only one mechanical vane sensor being used as bright as day!)
-
As I said before, I am not sure this plane will fly again with the same name.
It has a bad reputation and people don't want to fly in it anymore.
You've said it before, and I'll say again that there's a zero percent chance this will happen.
The DC10, for example,
Lets continue over a year and we will see.
Referring to planes of the 70s makes no sense, society has changed too much esp social media, internet....
If airliners are cancelling orders it looks bad, I can't say I can blame them.
-
It wouldn't be the first time the sensor is ok but the sensor data that arrives to the flight computer isn't, due a software bug somewhere else.
https://en.wikipedia.org/wiki/Qantas_Flight_72#Final_report (https://en.wikipedia.org/wiki/Qantas_Flight_72#Final_report)
At 12:42:27 the aircraft made a sudden uncommanded pitch down manoeuvre, recording −0.8 g, reaching 8.4 degrees pitch down and rapidly descending 650 feet (200 m) in about 20 seconds before the pilots were able to return the aircraft to the assigned cruise flight level. At 12:45:08 the aircraft then made a second uncommanded manoeuvre of similar nature, this time reaching +0.2 g, 3.5 degrees pitch down and descending 400 feet (120 m) in about 16 seconds before being returned to level flight.[14][15] Unrestrained passengers and crew as well as some restrained passengers were flung around the cabin or crushed by overhead luggage as well as crashing with overhead compartments. The pilots stabilised the plane and declared a state of alert (pan-pan), which was later updated to mayday when the extent of injuries was relayed to the flight crew
[...]
Final report
Analysis
After detailed forensic analysis of the FDR data, the flight control primary computer (FCPC) software and the air data inertial reference unit (ADIRU), it was determined that the CPU of the ADIRU corrupted the angle of attack (AOA) data. The exact nature was that the ADIRU CPU erroneously relabelled the altitude data word so that the binary data that represented 37,012 (the altitude at the time of the incident) would represent an angle of attack of 50.625 degrees. The FCPC then processed the erroneously high AOA data, triggering the high-AOA protection mode, which sent a command to the electrical flight control system (EFCS) to pitch the nose down
https://www.youtube.com/watch?v=2cSh_Wo_mcY (https://www.youtube.com/watch?v=2cSh_Wo_mcY)
-
well this is getting interesting
so AOA indicators is an option?
like a software addon in oscilloscopes? :-DD
but they are still suppose to tell the pilot there is a stall? or it did not?
The Wright brothers had (only) an AoA sensor and gauge indicator on their 1903 Flyer. It was a piece of yarn tethered on a stick.
I'm glad Boeing remembers it's kind of important, since day one.
"[Boeing] announced it would now make standard an indicator light that warns pilots of a sensor malfunction"
"A U.S. airline source said that feature would cost roughly $80,000 extra" :palm:
https://www.cbsnews.com/news/boeing-737-max-plane-crash-company-to-make-standard-light-warning-pilots-of-sensor-malfunction/ (https://www.cbsnews.com/news/boeing-737-max-plane-crash-company-to-make-standard-light-warning-pilots-of-sensor-malfunction/)
edit: added cost
-
And no programmer is going to work for a company on H1B for a few years.
Usually it's OPT->H1B->EB3->Green card.
If I work for a company and I don't see my I140 filed the next year I got H1B, I'll see myself out.
It happens all the time. At a previous job I had we had several developers on H1B visas for years. I'm not a fan of that system but it's not a rare situation.
-
Lets continue over a year and we will see.
Referring to planes of the 70s makes no sense, society has changed too much esp social media, internet....
If airliners are cancelling orders it looks bad, I can't say I can blame them.
Irrational behavior has become more common it seems, but I'm still quite confident the max will fly again. All new aircraft have teething problems, and occasionally this leads to disaster. When the Dreamliner battery fires were happening I saw a lot of people say that was the end of the line for those and people wouldn't fly on them yet here we are.
Once the problem has been fixed and the planes are sufficiently tested I would not hesitate to fly on a 737 max. Looking at it rationally, even if nothing were fixed and we just started flying the planes again, I'm still much more likely to die while driving to the airport in a car than in a plane crash from a statistical standpoint. Just to put this into perspective, approximately 50,000 people are killed each year in car accidents in the USA alone. That's approximately a 737 crash every single day of the year in deaths, yet people think nothing of getting into a car.
-
The only conclusion of my own that I've brought up here, really, is that it is looking a bit like this project contained a high level conspiracy to avoid corporate responsibility and save money, at the cost of human safety and now lives... So a thorough investigation into the decisions made by the key high-level people responsible for this project should to be a big priority, and if found to be a criminal conspiracy or even the slightest hit of unethical behaviour, they should be going to prison for consecutive life sentences for each person that died on those planes.. And I'll argue that all day, given what we've heard about the way the project certification was managed, the way new plane introduction and training was managed, and how different this plane apparently is to the plane it's certified to be..
This is a whopper of a conclusion. Though I agree there should be an investigation, and that if there criminal conspiracy or negligence are discovered, there should be punishment, neither of those things are established yet, not even close.
- is the idea of putting large engines on a 737 fundamentally flawed?
- is this airplane significantly different from other 737 that it should have required a type rating?
- if this plane pitches up more at already high AOA's, does that make it fundamentally unsafe?
- is the MCAS concept fundamentally flawed?
- is the MCAS system engineered poorly?
- should it be required for two AOA sensors to agree to activate MCAS?
- did Boeing know (or suspect) that the concept (or implementation) was flawed?
- did Boeing, or people at Boeing, know the airplane was unsafe? Did management override them?
- did Boeing hide information from the FAA? Did they use political power to force the FAA's hand?
NONE of these things are known right now, and they all matter. People seem to think they know the answers to these, but they do not, not even aviation experts.
My contention on this thread all along has been that aviation accident chains are long and complex, and that just because the plane is flawed or broken in some way does not mean the pilots acted competently. I think there's good evidence (not proof) already that the pilots involved did not perform in an exemplary fashion. Was their performance within the expected bounds for pilot capability? That will be another question for investigators to determine, too.
However, that, too is a separate question, and is distinct from everything that might be bad about the airplane, process, or organization that created it.
-
FBI have joined a criminal investigation into the 737 max. certifications.
Boeing essentially putting a "CE" sticker on their planes- they do not have the integrity to do self-certification.
We can keep haggling over the MCAS implementation but, as with many disasters, engineers were steamrollered into deploying something as quickly as possible and thus unsafe.
I think the profession has a huge problem- whistle blow and get fired, or join the corporate group think, keep your job and proceed with corrupt management's instructions.
I see it happening more with other scandals such as Volkswagen emissions , FIU bridge collapse, Theranos, Takata air bags etc.
The executives drive the company hard to maximize shareholder's profits as fast a possible, the result is unsafe products, and all the while the engineer's little voice is ignored.
We're somehow expected as PE's to act only with integrity despite our higher ups overruling that. Boeing surely had engineers that knew this MCAS rollout is shit, Arduino-crowd kind of software quality and bypassing necessary safety design and evaluations. But dare speak up about it and get thrown under the bus.
I'm not sure when or how corporate greed is going to get moderated, how many lives must be lost. Boeing took it to a new level but I can't see anything fixing this.
-
Post by Ralph Nader, who apparently lost a relative in one of the crashes.
Greedy Boeing’s Avoidable Design and Software Time Bombs (https://nader.org/2019/03/21/greedy-boeings-avoidable-design-and-software-time-bombs/)
-
Boeing: you third world airlines just need to hire armchair pilots to fly these planes. Every armchair pilot would have cut the stab trim, and they would not have wanted to know what MCAS did or why it was needed, esp whenever they made high AOA maneuvers, thereafter, for whatever reason.
-
Boeing: you third world airlines just need to hire armchair pilots to fly these planes. Every armchair pilot would have cut the stab trim, and they would not have wanted to know what MCAS did or why it was needed, esp whenever they made high AOA maneuvers, thereafter, for whatever reason.
I'll promise not to fly any airliners if you'll promise to stay off accident investigations.
-
https://www.youtube.com/watch?v=cQirIH_DuAs
You take it too personally, Djacobow.
Serious question: What it takes seconds for an MCAS malfunction to do, how long does it take to undo that after you cut the stab trim? After you cut the stab trim you can't just press the up button on the yoke anymore, right? You have cut all powered control over the jack screw and the horizontal stabilizer. It looks like you'd be turning the wheel for a long time.
As for pilot reaction: If you are used to hearing this thing clacking away during autopilot trim adjustments, then you might not notice it, at all? During AF447, the audio stall warning went off 70 times for over 2 minutes, and the black box recordings suggest that the pilots never even discussed a stall. Some studies have suggested that audio warnings don't register to the pilot under many circumstances, which is why most of the important alerts are not audio, only.
So, when the MCAS goes haywire, the pilots immediate reaction might be nothing. Then after awhile, they might have either tuned out the trim wheel adjusting altogether. Or they might realize, "hey, that trim adjustment has been going on for longer than usual." They might then first wonder why autopilot is turned on when they are sure it is off. Then they might turn off the autopilot (redundantly). Say for sake of speculation that the MCAS just happened to finish doing its thing at the time the pilot pushes the autopilot disengage button. Then he pushes the manual trim button, to get the trim back up. And it works as he expects. Problem solved... but not yet. It happens again. And pilot is on the wrong road from here on out.
Turning ON autopilot would have disabled MCAS. But it might have looked like the autopilot was malfunctioning. Simply knowing MCAS existed could make a huge difference in response.
One of your primary algorithms when flying this plane might be that if instruments are malfunctioning, you can always turn off the autopilot and fly, manually. When you think the autopilot is turning itself on/off and malfunctioning, then you might get some panic and tunnel vision, because your major "out" and feeling of control and safety has been removed. Now your tunnel vision has you locked on the autopilot disengage button, because hitting it seemed to have worked the first time, and now you think the autopilot is trying to kill you. It's obviously not a runaway trim, because it seems to have something to do with the autopilot, and it is not continous. When you press the trim up, it works. When you press trim down, that works. Trim controls are working. Training was maybe very specific under what condition you cut the stab trim, and in the moment the pilot is probably reverting to training and not able to think so clearly due to being so close to death at a fairly low altitude. He's not able to reason that cutting stab trim will prevent autopilot from using it, too (or MCAS, secret autopilot that is the "manual" autopilot). He is following his checklist.
-
You take it too personally, Djacobow.
:-)
Serious question: What it takes seconds for an MCAS malfunction to do, how long does it take to undo that after you cut the stab trim? After you cut the stab trim you can't just press the up button on the yoke anymore, right? You have cut all powered control over the jack screw and the horizontal stabilizer. It looks like you'd be turning the wheel for a long time.
Yes, a reasonably long time. I'm a bit surprised that nobody has uploaded a YT video that shows how long it takes to move the trim 2.5 degrees. The wheel spins fast under trim control and just by grabbing the wheel you probably can't even go 1/3 as fast. However, the wheel has a flip-out knob, that you can grab to crank it much faster. I guess it goes as fast as you'd want. My guess is that it would take roughly 2x as long as the trim motors when you're using the knob.
As for pilot reaction: If you are used to hearing this thing clacking away during autopilot trim adjustments, then you might not notice it, at all? During AF447, the audio stall warning went off 70 times for over 2 minutes, and the black box recordings suggest that the pilots never even discussed a stall. Some studies have suggested that audio warnings don't register to the pilot under many circumstances, which is why most of the important alerts are not audio, only.
Fair point. I think it's true that people focus on one thing to the exclusion of others, and this is a known problem in aviation. I didn't know the thing about sound in particular. Information saturation and other sorts of "data absorption" problems have been studied a fair bit in the context of instrument flying: instrument fixation, instrument omission, etc. There's also a lot of work around how long it takes a pilot to work out which instrument has failed. This is something you practice when instrument training, but under pressure, in hard IMC, with a debilitated airplane is a lot different, it has definitely proven fatally difficult.
I had not heard much about people tuning out klaxons, bells, and audio in particular, but to a first approximation, I'd think I'd almost have to tune them out in order to think.
AF447 makes an interesting comparison. The pilot flying may not have known he was stalling because he might not have thought it was possible. Normally, the Airbus provides envelope protection, which means you can yank back on the control stick and the plane will climb at the highest rate it can do so safely. However, because of the pitot fault there was no air data and the computer punted to alternate law without envelope protection. There would have been a screen indication, but who knows if the pilot would have understood it.
AF447, though, is also an example where a pilot could have flown this airplane out of the situation. "All" the pilots needed to do was fall back to early training, attitude flying: pitch + power = performance.
But I also understand why this would have exceedingly difficult: one moment you're monitoring a plane cruising on autopilot, the next moment you are hand-flying a plane not just manually, but one without air data and without the normal FBW characteristics of the A320. I can only imagine it's a jarring and difficult transition.
To my gut, I think I'd rather have the MCAS situation,, but I'm not sure it's productive to compare totally different incidents in totally different airplanes.
-
Is it just me, or does anyone else think that there's something immoral about Boeing designating functionality that is for the sole purpose of increased flight safety (such as the "disagree light") as "optional" and charging extra for it? And thus allowing corporate airline customers to opt-out of paying for it to be implemented in their aircraft? Comfort and operational economy options, sure. But items that can only be classified as "safety-related" and designed to notify when the rest of the aircraft isn't performing up to its paid-for specifications at the potential expense of all the lives aboard? Apparently, Boeing has a corporate policy which holds that not all passengers deserve equal levels of flight safety.
Automatic braking systems and lane assist are options on cars that are purely for safety. It costs money to implement these things, someone has to pay for it.
-
Video explaining and possibly answering questions regarding horizontal trim and MCAS:
https://www.youtube.com/watch?v=xixM_cwSLcQ (https://www.youtube.com/watch?v=xixM_cwSLcQ)
-
Post by Ralph Nader, who apparently lost a relative in one of the crashes.
Greedy Boeing’s Avoidable Design and Software Time Bombs (https://nader.org/2019/03/21/greedy-boeings-avoidable-design-and-software-time-bombs/)
That's Ralph Nader though, he made a career of criticizing products, greatly exaggerating their flaws. The most famous probably being the Chevy Corvair which was a surprisingly innovative car years ahead of its time. It had some unusual handling characteristics but it was not inherently dangerous for what it was, a car designed to be affordable and fuel efficient with the technology available at the time.
https://www.youtube.com/watch?v=NI9Hq0_Mhy0 (https://www.youtube.com/watch?v=NI9Hq0_Mhy0)
-
Is it just me, or does anyone else think that there's something immoral about Boeing designating functionality that is for the sole purpose of increased flight safety (such as the "disagree light") as "optional" and charging extra for it? And thus allowing corporate airline customers to opt-out of paying for it to be implemented in their aircraft? Comfort and operational economy options, sure. But items that can only be classified as "safety-related" and designed to notify when the rest of the aircraft isn't performing up to its paid-for specifications at the potential expense of all the lives aboard? Apparently, Boeing has a corporate policy which holds that not all passengers deserve equal levels of flight safety.
Automatic braking systems and lane assist are options on cars that are purely for safety. It costs money to implement these things, someone has to pay for it.
I can see both sides here, however in the case of the sensor disagree warning it sounds as if it's purely a software change. Now charging additional money to unlock a software feature is nothing new but I can see the argument over it being a safety feature that should be included standard rather than charging extra.
Automatic braking and lane departure systems require additional hardware that must be included in the car and they're less necessary IMHO than something intended to monitor for fault conditions. A person who pays attention when they drive doesn't need automatic braking or lane departure warnings, but it would be silly for a car manufacture to charge extra money for the brake system failure indicator.
-
You can charge for ABS because the DOT says it is legal to sell and drive cars without ABS. At one point cars didn't require a chest belt in the rear seat or air bags up front.
Just like the FAA cleared the MAX plane as fine without the AOA disagree warning.
I don't think the disagree light is the problem, though. Nor a display. Prior to the MAX, the AOA on a 737 was only ever used to activate a stick shaker. So a malfunction might have erroneously made the stick shake and nothing more? And these two crashes were not stalls.
Nondisclosure of MCAS is a problem. MCAS able to erroneously retrigger without any absolute limit is a problem.
Lack of ability to turn off MCAS is another problem. Stab trim cutout to kill MCAS is like cutting off your arm to spite your hand.
-
I think the reasoning behind not having a separate way of disabling MCAS is that without it the plane does not handle the same as other variants of the 737 and the system is intended to be transparent and effectively part of the trim system. I don't know that having to shut off power to the trim system is too unreasonable in that context which assumes that MCAS is going to behave sensibly. I mean in an Airbus plane you can't shut off envelope protection entirely, the automated systems are considered integral to the flight controls. Quite a few military fighter aircraft are inherently unstable and would drop out of the sky without the automated control systems so you can't shut those off either.
If it turns out that the MCAS system is responsible for these crashes I think the sensible thing to do is redesign it so that it cannot trim down to such an extreme that the pilot cannot override the pitch down trim with up elevator and then come up with a way to make it far more failsafe. I'm fairly confident that a solution can be engineered that will solve whatever problem exists. Boeing knows that they have one shot at this and another related crash after the design is corrected will have a far greater impact.
-
I don't know that having to shut off power to the trim system is too unreasonable in that context which assumes that MCAS is going to behave sensibly. I mean in an Airbus plane you can't shut off envelope protection entirely, the automated systems are considered integral to the flight controls.
The pilot might not be able to turn off certain protections on the Airbus. But these systems will turn off, automatically, if vital sensors fail, else they might contribute to a problem due to erroneous information. The MCAS doesn't automatically shutoff, even if you had purchased this AOA disagree alert upgrade. It just means you have to see it and then shut off your trim control and break out the crank handle, lol. Since at the time of the first crash, Boeing didn't even tell anyone about MCAS, an AOA failure alert would not have even resulted in any response. "Oh the AOA's don't agree. I'll stop relying on my AOA readings, is all. I never looked at that, anyway. Carry on." They wouldn't have cut the power to trim control to preempt a faulty MCAS response, because MCAS wouldn't even have been in their vocabulary.
Engineering standpoint: it seems barbaric the way MCAS works to begin with. How or why a 2.5 degree stabilizer response would ALWAYS be appropriate seems insanely crude. Matter not where the stabilizer started at, nor what the pilots may have already begun doing with the elevators, nor what the pilot has perhaps started doing with the elevators after MCAS started its one, crude, barbaric, quantum response. What if the AOA changes and says the AOA is normal and/or at least on the way down (due to faulty sensor or wind turbulence or whatnot.. or because the pilot had already applied full down elevators before reaching the AOA limit where MCAS kicked in)? Does the thing just continue cranking to 2.5 degrees down, anyway, and as soon as it's done it is ready for the next triggering? I mean, damn, the way it is described, I could write that software. Anyone could whip that up in an afternoon. And I think most engineers would see why it could be a problem.
Also it seems insane that MCAS makes this permanent and huge change to prevent the stall. Then it just leaves the stabilizer there. And Boeing doesn't think anyone needs to know. If the pilot had approached the stall because he accidentally turned the trim up by 2.5 degrees, unwittingly, and then didn't notice that the MCAS turned it back down to about "normal," then yeah, that would be a great behind-the-scenes response that the pilots need not be aware of. I mean, if the pilot inadvertently pressed the trim up button for 10 seconds and then immediately went unconscious for the the next minute, that would be perfect. In 99% of proper activation, this wouldn't be the case. And I bet the MAX with 2.5 degree nose down trim and no longer in a stall is going to handle a little differently than a normal 737. I suppose the pilot should be automatically executing the grab-the-wheel, cut the stab trim routine the instant it starts... since he is unaware it is supposed to happen. Then fix the plane from stalling, manually.
-
Doomed Boeing planes lacked two optional safety features (https://www.theguardian.com/business/2019/mar/21/doomed-boeing-737-air-max-planes-ethiopia-indonesia-crashes-lacked-two-optional-safety-features-report)
Safety feature.
Optional.
Extra cost.
:palm:
“They’re critical, and cost almost nothing for the airlines to install,” Bjorn Fehrm, an analyst at the aviation consultancy Leeham, told the newspaper. “Boeing charges for them because it can. But they’re vital for safety.”
I bet there are people at Boeing who now wish they had made both standard equipment.
-
That's Ralph Nader though, he made a career of criticizing products, greatly exaggerating their flaws. The most famous probably being the Chevy Corvair which was a surprisingly innovative car years ahead of its time. It had some unusual handling characteristics but it was not inherently dangerous for what it was, a car designed to be affordable and fuel efficient with the technology available at the time.
And as a result of "greatly exaggerating their flaws", Ralph Nader was instrumental in the introduction of mandatory seatbelts in the US and Canada, as well as the introduction of collapsible steering wheels (among other influential changes), both innovations resulting in saving the lives of many thousands of people. Unsafe At Any Speed was the book that started his "career of criticizing products".
<incorrect quote attribution corrected - apologies.>
-
That's Ralph Nader though, he made a career of criticizing products, greatly exaggerating their flaws.
...
And as a result of "greatly exaggerating their flaws", Ralph Nader was instrumental in the introduction of mandatory seatbelts in the US and Canada...
Well, I'm not the one who said that, but it's no big deal.
I did already know who Ralph Nader is. I had a Corvair as a daily driver for a while back in the late seventies. It was fine until a wheel fell off.
If you go to his site to read his comments about "Greedy Boeing", the post "Letter to the FCC Commissioners" is also pretty good.
-
yet people think nothing of getting into a car.
Oh there we go again comparing anything to cars :palm:
If you do want to compare it you should look at only those accidents with:
- a professional driver
- no alcohol involved
- no other cars or other vehicles/pedestrians involved
- no corners or bad roads, not within city limits (a straight highway without other traffic)
- no speeding or other traffic violations like crossing red lights etc.
If you look at all this the chance of a passenger surviving such an accident with all the safety precautions like airbags, belts, crackle zones is way higher than any passenger in a plane accident.
( please put your head between your legs and brace for impact and oh yeah we put the chairs so close to eachother anyone taller than 1m85 will probably hit the seat in front of him first, nice knowing you). Individual Passenger safety in a plane is the same as in the 50s , it has even been made worse by stuffing more and more people per square meter in that flying can.
-
the Chevy Corvair which was a surprisingly innovative car years ahead of its time.
Nothing in the Corvair was "surprisingly innovative" or ahead of its time. No thing at all. It was just an exercise of cost cutting by bolting down together the worst of the worse to make it cheap, as cheap and bad as a Renault 8 in the 60's or a Dauphine (its predecessor) in the 50's. The only time I've seen on the road with my own eyes a car rolling over for no reason, it was an R8. There's nothing worse when cornering than that swing axle suspension https://en.wikipedia.org/wiki/Renault_Dauphine#Technical
The rear swing axle design, unless ameliorated by any of several options, can allow rear tires to undergo large camber changes during fast cornering, leading to oversteer – a dynamically unstable condition in which a vehicle can lose control and spin. Renault relied on a front anti-roll bar as well as tire pressure differential to eliminate oversteer characteristics – low front and high rear tire pressure — and induce understeer. The tire pressure differential strategy offered the disadvantage that owners and mechanics could inadvertently but easily re-introduce oversteer characteristics by over-inflating the front tires. In the United States, drivers (and General Motors) experienced virtually the same issues with the Chevrolet Corvair. In 1960 Renault revised the suspension with the addition of extra rubber springs up front and auxiliary air spring units (mounted inboard of the conventional coils) at the rear – marketing the system as Aerostable[18] – and giving the rear wheels a small degree of negative camber and increased cornering grip
-
So, operating under the assumption that MCAS is what failed, my take on this is that Boeing screwed the pooch in the implementation of MCAS.
he thing is, having an inherently aerodynamically unstable airframe and using software to make it what I'll call "apparently stable" to the pilots is a completely valid design approach. (Think of the Segway scooter, which is only possible because of software.)
I absolutely agree... some forms of instability can definitely be patched with control systems, and the segway is a great example.... I would never claim otherwise.. but if you're going to do that, the system has to be fit for purpose...
And when we are talking about a plane where a critical error kills everyone on board, that system has to be robust and it has to be incapable of killing people no matter what you throw at it.
Yes. I think I kinda alluded to all of that in the sentence that followed the quote, namely "So, operating under the assumption that MCAS is what failed, my take on this is that Boeing screwed the pooch in the implementation of MCAS."
And when you're talking about a massive complex thing like a plane where pilots have to be able to override the system if it's going wrong, well you also have to be frank and open about what the plane is, how it actually works, and how it might be different from other planes you've ttold people it's the same thing as..
Yep. I was only talking about the equipment deficiencies, not the training and processes.
Both of these flaws have to be in place at the same time for the crashes to happen in the way we suspect as of right now. Fixing either one would have prevented the crashes. And both are comparatively easy to fix, so if I were Boeing, I'd fix both.
you'd also have to fix the documentation and the training and probably the plane type, but yes I agree, if the MCAS could be made to not fall down in a screaming heap and kill everyone on board, it could possibly be a suitable fix for the planes physical instability, as long as people piloting the plane were fully aware of what it was doing, why it was there, and had some experience flying the plane without it enabled.
What do you mean by "fix the… plane type"?
Also, whoever let the plane design out with such obvious holes in the design needs to be seriously investigated (like, did anyone even consider a basic system level FMEA on this thing? that should have pointed out the issue with only one mechanical vane sensor being used as bright as day!)
Yep. As I said, I was only addressing the equipment. But you're right that a root cause analysis will expose the organizational deficiencies that allowed such sloppy work to go out, and it's not gonna look good for Boeing!
-
As I said before, I am not sure this plane will fly again with the same name.
It has a bad reputation and people don't want to fly in it anymore.
You've said it before, and I'll say again that there's a zero percent chance this will happen.
The DC10, for example,
Lets continue over a year and we will see.
Referring to planes of the 70s makes no sense, society has changed too much esp social media, internet....
If airliners are cancelling orders it looks bad, I can't say I can blame them.
Nah. People have always been skeptical of aviation, and so mob mentality around failures has been a constant companion to the industry, even pre-social-media. So yeah, the DC10 is still a valid example.
Airlines cancel orders all the time. It's just basic risk reduction. They'll re-order (the same or something else) once the dust has cleared.
(FYI: "Airliner" means a passenger aircraft for public carriage by an airline. "Airline" means a company who operates such flights.)
-
Nothing in the Corvair was "surprisingly innovative" or ahead of its time. No thing at all. It was just an exercise of cost cutting by bolting down together the worst of the worse to make it cheap, as cheap and bad as a Renault 8 in the 60's or a Dauphine (its predecessor) in the 50's. The only time I've seen on the road with my own eyes a car rolling over for no reason, it was an R8. There's nothing worse when cornering than that swing axle suspension
Clearly you've never driven one, and are not particularly familiar with other American cars of the time. In the era of big lumbering front engine iron V8 powered cars the Corvair came along with a rear mounted alloy case air cooled horizontally opposed 6 cylinder, it was like nothing else out of Detroit at the time. They also offered one of the very first turbocharged engines in a consumer vehicle decades before Saab refined and popularized the technology. It was incredibly innovative for GM, a radical departure from the status quo. Yes it was cheaply made, it was designed to be affordable, it was designed to be fuel efficient which meant small and light weight. It was not high end, but it was nowhere near as bad as many people think based only off Nader's book having never even seen a real Corvair up close. They were no less safe than countless other low cost cars of the era.
-
You can charge for ABS because the DOT says it is legal to sell and drive cars without ABS. At one point cars didn't require a chest belt in the rear seat or air bags up front.
You're confusing ABS and collision avoidance systems, aka autonomous emergency braking (AEB).
This was the original statement:
Automatic braking systems and lane assist are options on cars that are purely for safety. It costs money to implement these things, someone has to pay for it.
By automatic braking system, he means AEB, where the car uses sensors to identify obstacles ahead and apply the brakes automatically. (Sort of an always-on extension of the hardware used for adaptive cruise control.) This is not required by law.
ABS means anti-lock braking system, where the car will automatically pulse the brakes to prevent the wheels from spinning out, retaining steering control in a skid. ABS has been mandatory on all new cars in the EU since 2004, and it's been de-facto mandatory in USA since 2012, when electronic stability control (ESC) became mandatory on new cars. (ESC builds upon ABS, adding more sensors and computing, and the ability for the system to apply brake power, not only release it.) ESC has been mandatory in the EU since 2014.
-
yet people think nothing of getting into a car.
Oh there we go again comparing anything to cars :palm:
If you do want to compare it you should look at only those accidents with:
- a professional driver
- no alcohol involved
- no other cars or other vehicles/pedestrians involved
- no corners or bad roads, not within city limits (a straight highway without other traffic)
- no speeding or other traffic violations like crossing red lights etc.
If you look at all this the chance of a passenger surviving such an accident with all the safety precautions like airbags, belts, crackle zones is way higher than any passenger in a plane accident.
( please put your head between your legs and brace for impact and oh yeah we put the chairs so close to eachother anyone taller than 1m85 will probably hit the seat in front of him first, nice knowing you). Individual Passenger safety in a plane is the same as in the 50s , it has even been made worse by stuffing more and more people per square meter in that flying can.
So are you asserting that getting into a car is less likely to kill you than getting onto an airliner? I'm not sure you understand how statistics work. What does the chance of surviving an accident have to do with this? The plane is far less likely to crash so even if you have a 99% chance of surviving a car crash and a 1% chance of surviving a plane crash the plane is still far less likely to kill you because plane crashes are extremely rare. They are so incredibly rare that whenever one happens it is front page news and we discuss the incident in threads like this. There are thousands of car crashes every day and many thousands of people die for other reasons every day. Yes having a professional driver would improve your safety, but how many people have one of those? Avoiding drugs and alcohol is obviously a big help, so is putting down the mobile phone but none of that helps when some other idiot hits you, and it happens, every single day.
Don't want to compare it to cars? Fine, here are the top 10 causes of accidental death from 2016. Maybe you can point out where airliner crash is on that list because I don't see it.
Poisoning (including drug overdose): 64,795, +11.1%
Motor vehicle: 40,231, -0.2%
Falls: 36,338, +4.8%
Suffocation by ingestion, inhalation: 5,216, +8%
Drowning: 3,709, -2%
Fires, flames, smoke: 2,812, +3%
Mechanical suffocation: 1,730, -2.9%
Natural heat, cold: 1,269, +6.7%
Struck by, against: 806, +2%, and
Machinery: 572, -6.2%.
-
So are you asserting that getting into a car is less likely to kill you than getting onto an airliner?
No. I say a car an sich as a vehicle is more safe than an airplane.
It is the circumstances that make it less safe and statistically have more deaths.
That is what i am saying and take for instance the Ford Pinto which was a very unsafe car because if hit from behind the fueltank could explode was avoided and abandoned by customers.
Which is probably what is going to happen to the MAX since for instance in Holland there were three MAX planes from TUI and after the accident people who booked their flight on one of these planes were massively cancelling their trip.
That was the discussion.
I'm not sure you understand how statistics work.
I know exactly how statistics work and the most important thing is to differentiate from the main subject to investigate vs all circumstantial parameters.
So the subject was NOT is driving a car safer than flying a plane, that was what you made of it so you could make a point. It was is a car safer than a plane.
Yes ofcourse it is, if something malfunctions on a plane in air and you can not control it anymore it is almost 99% game over. In a car it is not since you are still on the ground, you have crackle zones, airbags etc.
So all I am saying is that if a plane has a bad track record people are going to avoid flying on such a plane, that's all.
If they rename the plane and it has a longer safer track record than people will start flying again.
Pure social psychology.
-
Yes ofcourse it is, if something malfunctions on a plane in air and you can not control it anymore it is almost 99% game over. In a car it is not since you are still on the ground, you have crackle zones, airbags etc.
Cars are also much more likely to crash into something, since they are still on the ground.
-
Yes ofcourse it is, if something malfunctions on a plane in air and you can not control it anymore it is almost 99% game over. In a car it is not since you are still on the ground, you have crackle zones, airbags etc.
Cars are also much more likely to crash into something, since they are still on the ground.
Yes those are the other parameters as discussed, which is why an autonomous driving car is so much more difficult than an autopilot on a plane.
But thats not the discussion since it is just about the vehicle it self, if a customer has the choice to use a safe vehicle or an unsafe vehicle which will it choose, it is not that complicated.
That was my only point that customers will stay away from the MAX for the coming period, unless it is redesigned, found safe and probably rebranded to another name.
-
Tooki: yeah, ABS might be compulsory on cars in US, now, too. I'm not sure. But I do remember being offered ABS brakes as a ~$500-$1000 option on cars and motorcycles in my day. And I have never ridden a motorcycle with ABS. Point being, until it has been mandated as a requirement, this is ok to do.
AOA were used in commercial planes just to activate a stick shaker until very recently. There was never an AOA display (non military planes). And there was never a reason to need two sensors or double redundancy/agreement to activate a stick shaker stall alert. The stick shaker going off might confuse a pilot the first couple times, but the human response to a stick shaker is unlikely to cause a crash. Only perhaps in zero visibility at low altitude with ASI and/or altimeter both broken and a pilot that still really trusts his stick shaker and does not have the normal human fear of crashing into the ground. This is what the MCAS does; with no input from the horizon, pitch, speed, or thrust, altitude, it will (apparently) blindly respond to AOA sensor. This is why MCAS would need redundancy, per FAA's own guidelines, according to the Seattle Times article.
An AOA display is never going to be super critical in a commercial plane, if not for the MCAS. After a very short takeoff over a mountain, it will tell you that you could take maybe 100 lbs more, next time. But commercial planes are not operated like that. Their weight limit might go up, but it will be through a pile of bureaucracy. AOA display might help Sunday pilots explore the limits of their planes and increase their skills, but commercial pilots aren't allowed to do that. Losing $100 million dollar planes and killing pilots in training would be very costly, nevermind the cost of the fuel. Sticking to strict rules and narrow flight conditions already works fine for passenger transport planes without needing Top Gun pilots. A bus driver might be more capable of handling unusual conditions if Grey Hound taught him how to drift a bus around corners, but that ain't happening, either.
Planes are safer than cars, of course, when adjusted per mile. They travel a lot more in less times. I bet they (commercial) are safer per hour, as well. But even if they weren't safer, they still wouldn't make the top ten list of causes of accidental deaths, because most people don't fly very much, but many people drive several times a week, with a good portion of the world driving at least 5 days a week to work and one day a week to church. You can be captain of a 737 with some thousand of hours of actual flight time. Many of us have spent 100 times that in a car or bus.
-
it was like nothing else out of Detroit at the time.
That's true, but was a change for the worse. GM fooled you, in Europe we have had many cars like that not because they were better, but because they were cheap!
-
[That is what i am saying and take for instance the Ford Pinto which was a very unsafe car because if hit from behind the fueltank could explode was avoided and abandoned by customers.
I remember the Pinto hysteria, and that's what it was to a large extent. It ended up in a massive recall (major at the time, pretty minor by todays standards) to install a plastic barrier and a new filler tube, and people kept driving them for another decade or more (I know of one still on the road today, there are probably a few more). Legal scholars have since written volumes about public perception vs actual facts in the courtroom.
If you actually look at the statistics for fatalities in cars for those years, you'd notice that the Ford Pinto was about average for cars of its type (subcompacts). And it was significantly better than some, such as the VW Beetle or the AMC Gremlin.
-
How far can you go offtopic
-
How far can you go offtopic
I wasn't the one who brought up the Ford Pinto (and Mercury Bobcat rebadge) as an example, but since you did, I gave you the benefit of my first-hand memories of it. Showing my age and still-decent memory.
I would have stuck with aviation disasters as examples of things the public got over myself...the DC-10 cargo door failures, the 737 rudder failures, or even the 727 inadequate training crash-landings (3 of them in a 3-month period) when the plane was still new.
Public hysteria is very much on topic. This thread wouldn't exist without it. History teaches us that this too will pass.
-
No. I say a car an sich as a vehicle is more safe than an airplane.
You're cherry picking and ignoring the big picture which is this. If you travel a given number of miles in a plane and the same number of miles in a car, you are more likely to die in the car, period. This is a mathematically demonstrable fact, it is not a matter of opinion or up for debate. Do you need me to provide the statistics?
Obviously it's because airplanes are far less likely to crash per mile traveled, not because of survivability. Nobody is saying that car accidents are not more survivable than plane crashes, but there are so many more of them that your risk of dying in one is far higher. Throughout my life I've been in at least 10 car accidents, most of them minor and none of them my fault but they happened none the less and one I was very lucky to walk away from. I've flown quite a bit too and I've been in zero plane crashes. Plane crashes are extraordinarily rare, hence flying is quite safe.
-
Fair enough, we will see what happens. I do 't think it will kill Boeing, as other people said too many existing carriers will have a huge problem when Boeing is gone. It will be impossible to retrain all pilots and technicians to Airbus planes so that is not going to happen IMO.
-
You're cherry picking and ignoring the big picture which is this. If you travel a given number of miles in a plane and the same number of miles in a car, you are more likely to die in the car, period. This is a mathematically demonstrable fact, it is not a matter of opinion or up for debate. Do you need me to provide the statistics?
No every child knows that this is not my point, you don't get it or don't want to get it.
Last time:
It is not the car that is less safe than the plane, it are the conditions in which people travel in car that is less safe than a plane.
If you do the same precautions with driving cars as flying a plane or vice versa if you let everybody even drunk fly 1000's of planes right across a small airspace you have the same amount of accidents.
I will try to visualize my point:
Car: You have to be a professional driver, do 200 hours of driving each year or your license is revoked. You need to be healthy , sober, do a thorough engine and car safety check before you start the car.
After every drive the tires are checked,brakes, fluid levels etc. etc.
You have to wait till travel control will tell you when you can drive away in your car, and exactly what route you should take. Travel control will make sure you encounter no other trafic within a mile, no cars , no bikes, no pedestrians or animals and that the entire road is clear for you to drive. If the weather gets very bad travel control will tell you to stop your car at the nearest possibility. Your speed is controlled, the time for your travel is controlled and you are not allowed to deviate from your path. In case you don't feel well there is a second professional driver besides you to take over.
Plane: 1000s of planes are behind eachother flying with less than 30seconds of distance from eachother, you have to look left and right all the time since there could be planes coming without warning even with drunk pilots or pilots that only got their license a day ago and do not know how fly very well. Also some other aircraft like drones or even missiles might come out of nowhere so be warned to keep an eye out. If the weather is very bad it is up to you if you continue flying even with zero visibilty, hopefully the planes before and after you have the same pace or a lot of them will crash into eachoter which is not good but happens all the time, esp. during rush hour when everyone is flying their planes to work.
-
the thing is, having an inherently aerodynamically unstable airframe and using software to make it what I'll call "apparently stable" to the pilots is a completely valid design approach. (Think of the Segway scooter, which is only possible because of software.)
To expound on this, one has to wonder if the MCAS system is adequate to even do this.
Take for example the anti-stall on an Airbus A330. During the Quantas incident, in response to (albeit erroneous) AOA information, the plane dipped very decisively at -0.8G. This was 1.8G, absolute! Yes, people bounced off the roof of the plane and some people suffered spinal cord injuries. In the Airbus, the flight computer has control over the elevators, not just the stabilizer. Compare that to the MCAS system that can make only gradual (but ultimately gigantic) changes to the attitude of the plane (and apparently won't undo this change AFTER), and you wonder how sloppy and inadequate a bandaid this is to begin with.
Compared to an Airbus, or even a Segway, the way the news has reported the MCAS makes it sound like Mickey Mouse dog poo which only billions of dollars of incentive could make it look like anything else to anyone.
When Airbus made the decision to retrofit their planes with larger engines to make the A320, Boeing engineers and executives thought it would be a bad decision for Airbus. They realized this would cause some major problems. When the 320 was successful, they tried to follow suite.
So when Boeing says they hid the MCAS system because they didn't want to overload pilots with too much information, that is not easy to believe. They tried to do the same thing Airbus did, but with the additional problems of the 737 being too low to the ground; the 737 handling cannot be tweaked by software to the same degree as the Airbus; and messing with the trim also subverted one of Boeing's core tenants and selling points.
-
No 737 MCAS, no burning Tesla battery, just the tranquility of 777 electric motor whine. :popcorn:
https://www.youtube.com/watch?v=OAiJxw7v9tw (https://www.youtube.com/watch?v=OAiJxw7v9tw)
-
That was my only point that customers will stay away from the MAX for the coming period, unless it is redesigned, found safe and probably rebranded to another name.
I still disagree.
What I think will happen is that the truth of whatever happened will come out and that there will be some obvious actions necessary. Depending on the nature of the issues identified, there may also be hell to pay - and that payment will be made.
Once the dust settles and the required changes have been implemented, the travelling public will be back on the MAX and if nothing further goes wrong over the ensuing year, then these two crashes will be all but forgotten by them.
-
Boeing will shortly be finished with their MCAS software fix, but who has confidence in it given the original software design was so poorly done and made it through testing and certification?
What makes the checks any better for this software iteration? How's the rest of the aircraft's design, testing, certification?
I think Boeing's corporate arrogance is going to be seen in full display as they try get the grounded planes back in the air as soon as possible. The pilot training takes time, it will be months before the planes are up and the CEO is still bungling the PR around the entire debacle.
The politics around this is nuts. Trade war fuelled, today: "Airbus SE secured a $35 billion jet deal from China"
Ouch.
-
Boeing will shortly be finished with their MCAS software fix, but who has confidence in it given the original software design was so poorly done and made it through testing and certification?
I'll have confidence in it given :
A) what this will have (and is going to) cost them;
B) the extreme scrutiny that will be applied by the international aviation community; and
C) the requirement to demonstrate to the flying public that these aircraft are airworthy.
Despite the odd oops (and this is a big one), there is a reason a considerable amount of the aviation world says "if it ain't Boeing, I ain't going".
Planes fall out of the sky. They always have, and they always will. The takeaway is always the lesson(s) learned and how they apply that moving forwards.
-
Despite the odd oops (and this is a big one), there is a reason a considerable amount of the aviation world says "if it ain't Boeing, I ain't going".
That slogan started when the 707 came, the 60s :)
Boeing publishes a list of planes that never had a crash,
ofcourse the longer a plane is in service , the more it is used , the higher the chance something happens.
The Safest Aircraft in the World
There are 10 major commercial jet aircraft that can claim to be the world’s safest after never recording a passenger fatality, according to Boeing. The annual Boeing Statistical Summary of Commercial Jet Airplane Accidents Worldwide Operations 1959 – 2016 lists the following aircraft as having a fatality-free record:
Boeing 717 (formerly the MD95)
Bombardier CRJ700/900/1000 regional jet family
Airbus A380
Boeing 787
Boeing 747-8
Airbus A350
Airbus A340
-
the thing is, having an inherently aerodynamically unstable airframe and using software to make it what I'll call "apparently stable" to the pilots is a completely valid design approach. (Think of the Segway scooter, which is only possible because of software.)
To expound on this, one has to wonder if the MCAS system is adequate to even do this.
Take for example the anti-stall on an Airbus A330. During the Quantas incident, in response to (albeit erroneous) AOA information, the plane dipped very decisively at -0.8G. This was 1.8G, absolute! Yes, people bounced off the roof of the plane and some people suffered spinal cord injuries. In the Airbus, the flight computer has control over the elevators, not just the stabilizer. Compare that to the MCAS system that can make only gradual (but ultimately gigantic) changes to the attitude of the plane (and apparently won't undo this change AFTER), and you wonder how sloppy and inadequate a bandaid this is to begin with.
Compared to an Airbus, or even a Segway, the way the news has reported the MCAS makes it sound like Mickey Mouse dog poo which only billions of dollars of incentive could make it look like anything else to anyone.
When Airbus made the decision to retrofit their planes with larger engines to make the A320, Boeing engineers and executives thought it would be a bad decision for Airbus. They realized this would cause some major problems. When the 320 was successful, they tried to follow suite.
So when Boeing says they hid the MCAS system because they didn't want to overload pilots with too much information, that is not easy to believe. They tried to do the same thing Airbus did, but with the additional problems of the 737 being too low to the ground; the 737 handling cannot be tweaked by software to the same degree as the Airbus; and messing with the trim also subverted one of Boeing's core tenants and selling points.
You completely misunderstand and misconstrue the circumstances.
It’s not as though the MAX handles radically differently, or is particularly unstable. (Software stability control has been used in flying wing aircraft, which are so unstable as to be practically unflyable by a human. But software can do it, presenting to a pilot an “apparently stable” aircraft. The 737 MAX is a much, much less demanding situation.) It’s a single handling characteristic that separates its handling from any older 737: its lift characteristics at high AOA. This single thing is trimmed in software not to make it easier on pilots, but to make the MAX retain the same type rating so that 737 pilots don’t need to be retrained and recertified in the MAX. This isn’t something where you’d want quick, sudden changes anyway, which is why it only controls the jackscrew in the back.
As I said earlier, Boeing made two technical mistakes: relying on a single AOA sensor (leading to a single point of failure), and allowing MCAS to re-trigger repeatedly without limiting its cumulative control input. And then the organizational mistakes were to not document the system and train pilots and airlines on it and how to disable it.
P.S. It’s “tenets”, not “tenants”. ;)
-
It's also worth noting, that pilots already know how to recover an MCAS fault. The MCAS is just an input to the auto trim system, which is disabled with the same switches that it always has been. While the system level design for the MCAS allowed for an unnecessarily high and extreme failure rate, the pilots theoretically already had everything they needed to diagnose and correct the fault.
The corrective action for an MCAS failure is simply the trim runaway checklist, which is a memory item. The argument being made is that an MCAS failure makes trim runaway harder to notice because the control input happened in bursts instead of continuously, and while that's true, I don't think it excuses the pilots. If you are fighting with a fault for eleven minutes, and during that time both crew-members fail to check one of the two control surfaces that could be directly responsible for that fault, then the crew's ability to fault find under pressure is unacceptably poor. Not every problem will look exactly like a scenario you have been shown before. We aren't talking about complex inferences here, we are talking about checking to see if a thing that points the nose down is pointing the nose down. At some point over an eleven minute period of the nose being pointed down.
-
The politics around this is nuts. Trade war fuelled, today: "Airbus SE secured a $35 billion jet deal from China"
Ouch.
Indonesian airline Garuda cancells 49 Boeing 737 MAX 8 $4.9 billion
Now FFA suddenly and "tentatively" certifies Boing MCAS to only dip nose for 10 secs and only once! Geeeee! :palm:
https://gizmodo.com/boeing-software-updates-to-fix-anti-stall-system-tentat-1833521139
Boeing CEO, president, and chairman Dennis Muilenburg said in a statement at the time that while it maintained “full confidence” in the model’s safety, the suspension was issued “out of an abundance of caution.”
“Safety is a core value at Boeing for as long as we have been building airplanes; and it always will be. There is no greater priority for our company and our industry,
No its not Boings core values you deepstate psychopathic asshole, its to make money else you would not have had a man-cave certified faulty design to begin with!
-
^That's not reassuring.
Firstly, there should be a way to disable MCAS without cutting out trim power. I don't see why not. Whether the flight goes on as planned or make an unplanned or emergency landing, why make the pilot use the crankwheels on top of that.
It’s not as though the MAX handles radically differently, or is particularly unstable. (Software stability control has been used in flying wing aircraft, which are so unstable as to be practically unflyable by a human. But software can do it, presenting to a pilot an “apparently stable” aircraft. The 737 MAX is a much, much less demanding situation.) It’s a single handling characteristic that separates its handling from any older 737:
It is stable as long as AOA is kept below what the 737 NG can do. It is admittedly UNSTABLE at high AOA. Unstable as in runaway towards stall. As previously discussed, there is nothing that MCAS does to make the MAX handle like the NG, despite how it is spun. More thrust makes the plane nose up. MCAS doesn't do anything to make the MAX not do this. It's only after it reaches or approaches an AOA where the NG would still be stable that the MCAS kicks in and says "no don't do that."
For an electronic doodad to make an area of runaway instability stable, it has to be able to react quickly. Making a static change to the stabilizer does not change the fact that the change in lift of the engine "nacelles" is NOT static. It increases with more nose up. Still unstable, no matter what static change you make as a bandaid. MCAS is maybe there to prevent the plane from reaching that point. It's only a "less demanding situation" because this high of an AOA would not be necessary except in unusual circumstances.
This is a big bag of conjecture, for sure. I am guessing from what we know. Maybe I'm wrong, but I think you could be wrong, too. I'm just speculating. If MCAS trim adjustment can actually keep up with this change in nacelle lift at high AOA... great. But the way MCAS has been described doesn't jive with this. To counterbalance the varying nacelle lift at varying AOA, the trim should have to be adjusting in an absolute way based on AOA. And in both directions. Not making relative adjustments, down only.
-
Remember there are two pilots in that cockpit. If the trim has to be adjusted manually instead of electrically, there's going to be a another hand available to do something if the flying pilot asks. Even in regular operation it's normal to verbally delegate some actions to the other pilot.
You're making too big a fuss about the word unstable. An SUV is admittedly more unstable than a sports car in a turn. The solution is to not take turns too fast in the first place, not scream and yell until SUV's are banned.
-
I'm looking at the word unstable as an engineer and from what we have been told. Instable has en engineering implication that is beyond "the plane will shake a little."
An SUV is admittedly more unstable than a sports car in a turn.
Not necessarily. An SUV might not be able to pull as many lateral G's, but it might be more stable, controllable, and recoverable in the event of loss of traction of the tires.
Take for example the Porche Carrera GT. In most other Porches and in many other (esp rear-drive) cars, the car can be oversteered in a predictable manner when the tires break loose. Some cars can be intentionally drifted on demand, even, with great control through the entire process. The Porche Carrera GT doesn't like to do this. Even an experienced driver cannot control this car when this happens, even if he expects it.
Some cars give more warning at the edge of traction. Some are more controllable and/or recoverable. It doesn't necessarily mean they are capable of lower lap times. The Carrera GT will run circles around the SUV... up until the driver exceeds the car's limit. There will be no warning, and at this point the driver is just along for the ride. He isn't going to lose 3 seconds on his laptime after recovering from a little slide. The car will spin out and go off the track, and he will be done for the day.
I'ver personally "drifted" a car unintentionally, twice. Once on an on-ramp that had iced. I had my car pretty near sideways. Second was on dry pavement. Country highway with 2 lanes in fog. Someone decided to park in the left lane with no lights on, and by the time I saw it, I could only swerve to the other lane. Probably avoided hitting the car by something like 10 feet at most. When I steered back to the left to stay in the right lane, my car's rear slid out by about 30 degrees. Both times I recovered with no problem and stayed on the road, because I knew what was happening and I knew what to do. And... the car was stable and predictable and controllable under that condition. Just ride it out. Apply oversteer to keep the front tires in the right direction, and the the car will eventually return to straight. You just have to expect that response and return the wheel to center as it does so, because it can happen fast. My passengers were pretty impressed, though.
-
Flight simulations recreating the problems with the Lion Air plane, pilots discovered that they had less than 40 seconds to override MCAS.
-
In an engineering sense, stability means that a lack of control input will causes the system to return to a steady state. Unstable means that a system with no control input will begin to deviate from its current state at an increasing rate. More stability comes with the cost that the system tends to be less responsive.
Things like cars slipping are scenarios where the system becomes strongly nonlinear and controlablity suffers. Stability isn't really the right thing to worry about. It's more that we are talking about operating regions with very different system dynamics which the operator may not know how to respond to, or the system may enter a region where it is no longer controllable due to actuator limits.
MCAS was designed to deal with a situation where the system was not controllable with elevator inputs, so an auto trim assist was added in that state region to make the system controllable. Stability/instability aren't really relevant there. In fact, this isn't even an issue of a strong non-linearity, it's just an issue of running into an actuation limit on the elevator control surface. The trim basically gives the elevators a boost.
-
Stability/instability aren't really relevant there. In fact, this isn't even an issue of a strong non-linearity, it's just an issue of running into an actuation limit on the elevator control surface. The trim basically gives the elevators a boost.
Great theory, but here are the holes. If MCAS basically gives the elevators a necessary boost, you're suggesting full elevator down wouldn't even prevent the plane from runaway nose up stall when in a condition where the NG would be considered to still be in a normal part of its envelope. Where the NG would still be stable, and by your definition, stable means the NG would return towards straight even if you let go of the stick, let alone push the stick forward. So the MCAS has to kick in and help the pilot do something he wouldn't even do. If he thinks he can just let go of the stick, and the plane will be stable, why would he push full forward?
By your reasoning:
1. Ideally, the MCAS would not even be needed. They would make the elevator larger and more powerful. They could even limit the upwards range a bit, to ensure that upwards elevator is not increased. Only the downwards effect is increased. Of course this might not be possible without major alterations and cost and time and recertification, and perhaps due to these reasons it would be better to just build a new plane from scratch, even though it sounds simple.
2. If the MCAS is only supposed to boost or extend the pilot's response, then it would ideally only activate when the pilot is already at full elevator down. MCAS would not do anything if the pilot is not at full elevator down. In the case of these crashes, the pilots were obviously giving full elevator UP. But maybe trim control is too slow for this to work and/or maybe as I suggested earlier, an NG pilot wouldn't even know to push the stick that far forward until it was too late.
Any way you slice it, it would appear that MCAS is potentially a pathetic bandaid on a pretty serious wound.
So no. I think non-linearity and instability are potentially a big part of the problem. If Boeing were willing to eat it and redesign/recertify a new airframe, they would have made the plane with taller landing gear so the engines did not have to mount in a way that produced instability in a given AOA range where the plane still has laminar flow and lift. To me, "unstable" potentially means that even if the pilot had the range of control (with help of MCAS or otherwise) to reign the plane back from here, this area of AOA would be difficult to control and essentially unsafe/unusable without some active electronic aid that can respond relatively quickly and dynamically... not just to slam the nose back down, but to enable the pilot to utilize and fly in this range of AOA in a predictable and controllable manner if and when the need should arise. If and when then need should arise, slamming the nose down might be less than ideal.
they had less than 40 seconds to override MCAS.
Which means cutting the stab trim and then cranking the wheel, which Djacobow suggests it is maybe 1/3 to 1/2 as fast without power. If they had already allowed MCAS to turn the wheels all the way down, taking 20 seconds with power... That would be a fun challenge of how much motor coordination do you have while spearheading into the ocean. On one of those flights, I read the plane was pitched 49 degrees down. Even 30 degrees is pretty steep. San Franciso's steepest streets are around 30 degrees, if you've ever driven there. It's unnerving on a road.
-
It's also worth noting, that pilots already know how to recover an MCAS fault. The MCAS is just an input to the auto trim system, which is disabled with the same switches that it always has been. While the system level design for the MCAS allowed for an unnecessarily high and extreme failure rate, the pilots theoretically already had everything they needed to diagnose and correct the fault.
The corrective action for an MCAS failure is simply the trim runaway checklist, which is a memory item. The argument being made is that an MCAS failure makes trim runaway harder to notice because the control input happened in bursts instead of continuously, and while that's true, I don't think it excuses the pilots. If you are fighting with a fault for eleven minutes, and during that time both crew-members fail to check one of the two control surfaces that could be directly responsible for that fault, then the crew's ability to fault find under pressure is unacceptably poor. Not every problem will look exactly like a scenario you have been shown before. We aren't talking about complex inferences here, we are talking about checking to see if a thing that points the nose down is pointing the nose down. At some point over an eleven minute period of the nose being pointed down.
This ^^^^^^^^^ is correct.
The Lion Air crew failed to identify the run away trim condition (Boeing calls it "Runaway Stabilizer") and/or did not take the appropriate corrective action.
The corrective action was very simple; set the Stabilizer Trim Cutout switches to CUTOUT.
MCAS or not; this was a "Runaway Stabilizer" condition.
Maybe the crew was confused because in addition to the trim runaway condition, the stick shaker was also activated. But this is my own speculation on the crew confusion.
The fault that activated the MCAS trim, also triggered the stick shaker.
The fact is; the crew did not take the appropriate corrective action for a "Runaway Stabilizer" condition.
You cannot miss when the Stabilizer Trim is being activated in a 737, as there is a loud bicycle chain noise coming from the center pedestal and you can see the large Trim Wheels rotating.
The Boeing 737 MAX is just like the 737 NG and the 737 "Classic"; a hands and feet aircraft. Once the Stabilizer Trim is in the Cutout position, it is still possible to trim the aircraft using the trim wheel, which is mechanically connected to the Horizontal Stabilizer Jack Screw. I suppose this is the same horizontal stabilizer trim system that Boeing had on the 707 and 727.
May the passengers and crew of Lion Air flight 610 rest in peace.
:(
-
^^^^
As for pilot reaction: If you are used to hearing this thing clacking away during autopilot trim adjustments, then you might not notice it, at all? During AF447, the audio stall warning went off 70 times for over 2 minutes, and the black box recordings suggest that the pilots never even discussed a stall. Some studies have suggested that audio warnings don't register to the pilot under many circumstances, which is why most of the important alerts are not audio, only.
So, when the MCAS goes haywire, the pilots immediate reaction might be nothing. Then after awhile, they might have either tuned out the trim wheel adjusting altogether. Or they might realize, "hey, that trim adjustment has been going on for longer than usual." They might then first wonder why autopilot is turned on when they are sure it is off. Then they might turn off the autopilot (redundantly). Say for sake of speculation that the MCAS just happened to finish doing its thing at the time the pilot pushes the autopilot disengage button. Then he pushes the manual trim button, to get the trim back up. And it works as he expects. Problem solved... but not yet. It happens again. And pilot is on the wrong road from here on out.
Simply knowing MCAS existed could make a huge difference in response.
One of your primary algorithms when flying this plane might be that if instruments are malfunctioning, you can always turn off the autopilot and fly, manually. When you think the autopilot is turning itself on/off and malfunctioning, then you might get some panic and tunnel vision, because your major "out" and feeling of control and safety has been removed. Now your tunnel vision has you locked on the autopilot disengage button, because hitting it seemed to have worked the first time, and now you think the autopilot is trying to kill you. It's obviously not a runaway trim, because it seems to have something to do with the autopilot, and it is not continous. When you press the trim up, it works. When you press trim down, that works. Trim controls are working. Training was maybe very specific under what condition you cut the stab trim, and in the moment the pilot is probably reverting to training and not able to think so clearly due to being so close to death at a fairly low altitude. He's not able to reason that cutting stab trim will prevent autopilot from using it, too (or MCAS, secret autopilot that is the "manual" autopilot). He is following his checklist.
On top of that this was the crew's first flight on a MAX. All the controls are different. Video displays replacing gauges. I can spend an hour looking for something on my own bench that is in plain sight, as it is.
The AF447 crew was western Europeans. The altimeter was never broke. The airspeed indicator came back to life in plenty time. The stall warning went off for 3 minutes. No one even said the word stall for over two minutes, until it was too late, anyway. When the captain returned to the cabin and they asked him what to do, his exact words translate to "fuck if I know." If cutting stab trim is flying 101, how bout knowing what a stall is? They put engines on full the entire time, so they didn't think the plane was going too fast and experiencing Mach turbulence. They knew the plane was dropping and their air speed was low.
-
On top of that this was the crew's first flight on a MAX. All the controls are different. Video displays replacing gauges. I can spend an hour looking for something on my own bench that is in plain sight, as it is.
The instruments panel, pedestal, overhead panel and flight controls on the 737 MAX are the same as on the previous 737 NG. And everything is so antiquated in a 737 NG, that it has to be the same as the 737 "Classic". Anyway, they have to be the same, as they all share a common Type Rating.
The flight instruments on the 737 MAX are different.
What was the flight crew flying before?
737 NG do not have gauges, but LCD screens. LCD screens in the 737 MAX are larger than the screen in the 737 NG, the 737 MAX probably use large screen similar to the 787.
I doubt an airline would expect pilots trained on the 737 "Classic" to jump into a 737 NG or 737 MAX without any transition training, as the information on LCD screen is not shown the same way as on steam gauges.
:)
-
What about the other stuff? The autopilot makes trim adjustments, right? The trim wheel moving itself is something the pilots would be accustomed to, and something they would attribute to the autopilot, no?
-
The instruments panel, pedestal, overhead panel and flight controls on the 737 MAX are the same as on the previous 737 NG. And everything is so antiquated in a 737 NG, that it has to be the same as the 737 "Classic". Anyway, they have to be the same, as they all share a common Type Rating.
Any difference between models is a potential point of defining the need for a new Type Rating - which becomes a costly exercise across the board. That's why they try and keep things as unchanged as possible. For example, the switch for the "No Smoking" sign is still in place, even though it hasn't been needed for many years. Removing it "changes" the aircraft.
-
What about the other stuff? The autopilot makes trim adjustments, right? The trim wheel moving itself is something the pilots would be accustomed to, and something they would attribute to the autopilot, no?
Your question is very good, and Boeing answer is very simple. The Boeing 737 Quick Reference Handbook (commonly known as QRH) reads, under "Runaway Stabilizer":
Condition: Continuing rotation of the stabilizer trim wheel in a manner not appropriate for flight conditions.
Autopilot (if engaged): DISENGAGE
If runaway continues:
Stabilizer Trim Cutout switches: (set to) CUTOUT
The contents of the QRH is supposed to be known by the pilots who are type rated in the aircraft they are flying. The 737 QRH Quick Action Index is one page of 15 items written in bold.
-
The politics around this is nuts. Trade war fuelled, today: "Airbus SE secured a $35 billion jet deal from China"
Ouch.
Indonesian airline Garuda cancells 49 Boeing 737 MAX 8 $4.9 billion
Ouch
-
Wow, the same plane had the same incident the day before, and a pilot in the jump seat knew what to do and saved the plane:
https://www.smh.com.au/business/companies/pilot-who-hitched-a-ride-saved-boeing-737-max-a-day-before-it-crashed-20190320-p515sq.html (https://www.smh.com.au/business/companies/pilot-who-hitched-a-ride-saved-boeing-737-max-a-day-before-it-crashed-20190320-p515sq.html)
-
Stability/instability aren't really relevant there. In fact, this isn't even an issue of a strong non-linearity, it's just an issue of running into an actuation limit on the elevator control surface. The trim basically gives the elevators a boost.
Great theory, but here are the holes. If MCAS basically gives the elevators a necessary boost, you're suggesting full elevator down wouldn't even prevent the plane from runaway nose up stall when in a condition where the NG would be considered to still be in a normal part of its envelope. Where the NG would still be stable, and by your definition, stable means the NG would return towards straight even if you let go of the stick, let alone push the stick forward. So the MCAS has to kick in and help the pilot do something he wouldn't even do. If he thinks he can just let go of the stick, and the plane will be stable, why would he push full forward?
By your reasoning:
1. Ideally, the MCAS would not even be needed. They would make the elevator larger and more powerful. They could even limit the upwards range a bit, to ensure that upwards elevator is not increased. Only the downwards effect is increased. Of course this might not be possible without major alterations and cost and time and recertification, and perhaps due to these reasons it would be better to just build a new plane from scratch, even though it sounds simple.
2. If the MCAS is only supposed to boost or extend the pilot's response, then it would ideally only activate when the pilot is already at full elevator down. MCAS would not do anything if the pilot is not at full elevator down. In the case of these crashes, the pilots were obviously giving full elevator UP. But maybe trim control is too slow for this to work and/or maybe as I suggested earlier, an NG pilot wouldn't even know to push the stick that far forward until it was too late.
Any way you slice it, it would appear that MCAS is potentially a pathetic bandaid on a pretty serious wound.
So no. I think non-linearity and instability are potentially a big part of the problem. If Boeing were willing to eat it and redesign/recertify a new airframe, they would have made the plane with taller landing gear so the engines did not have to mount in a way that produced instability in a given AOA range where the plane still has laminar flow and lift. To me, "unstable" potentially means that even if the pilot had the range of control (with help of MCAS or otherwise) to reign the plane back from here, this area of AOA would be difficult to control and essentially unsafe/unusable without some active electronic aid that can respond relatively quickly and dynamically... not just to slam the nose back down, but to enable the pilot to utilize and fly in this range of AOA in a predictable and controllable manner if and when the need should arise. If and when then need should arise, slamming the nose down might be less than ideal.
You don't have a clear picture of what is going on. The elevators are flaps on the the tailplanes. MCAS adjust the trim, which rotates the entire tailplane.
I'm saying that the whole concept of stability/instability isn't even relevant here, and your definition of instability is vague and inaccurate from either a control systems or aerodynamics point of view. A power on stall isn't stable or unstable. It's just a flight characteristic, and the issue is that in some situations, the elevator alone might not have sufficient actuator force to reach a leveled out state if you keep the new more powerful engine as full thrust. If anything it's a reachability problem, except it isn't, because we have additional control surfaces that we can use to evolve the system to the desired state. People are saying that this is bad, but there aren't any reasons given for it, other than vague handwaveing. There's no reason that you couldn't implement this with a manual trim control, and if the aircraft had been designed fifty years ago, that's exactly what they'd have done. This doesn't require some kind of fast processing loop to stabilize a highly unstable dynamic system like the B2 or something. It's literally just an automatic switch that makes the tail plane more steep to help the elevators out. The only reason the pilots don't do it manually is to reduce workload on the pilot. That's the whole reason that automatic trim systems exist in the first place.
On top of that this was the crew's first flight on a MAX. All the controls are different. Video displays replacing gauges. I can spend an hour looking for something on my own bench that is in plain sight, as it is.
Yeah, but the control and gauge they needed to get at was the same at is has been for fifty years.
-
Wow, the same plane had the same incident the day before, and a pilot in the jump seat knew what to do and saved the plane:
https://www.smh.com.au/business/companies/pilot-who-hitched-a-ride-saved-boeing-737-max-a-day-before-it-crashed-20190320-p515sq.html (https://www.smh.com.au/business/companies/pilot-who-hitched-a-ride-saved-boeing-737-max-a-day-before-it-crashed-20190320-p515sq.html)
You are slightly late to the show, but dont worry the fat lady haven't even been dressed up yet! :) On page 20!
https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2283120/#msg2283120 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2283120/#msg2283120)
-
Obi_Kwiet
Thanks for trying to enlighten me, but I disagree with most of what you wrote there. And I understand (at least since the last couple days) the difference between the elevators and the horizontal stabilizers. We do not agree what instability means in this application/context.
If you manually just adjust the trim down, this makes the plane stable at only one exact AOA. This is great if you want to leave the plane exactly there, and then continually baby sit it with manual inputs so it doesn't change. Operating in an unstable area means (to me) if you inadvertently let the plane's attitude drift slightly down, that amount of trim you dialed in is now too much, and the plane will nose down in increasing rate. And if the plane drifts up a little, it will not be enough, and the plane will nose up ever more increasing. Because the plane is not stable in this range of AOA. It's like you are correcting me with your abstract definitions of stable vs unstable. But when I say the same thing, but in the context of the plane, you disagree. In my understanding, you cannot correct for instability with a static change. Now if the horizontal stabilizer increased in effectiveness at a higher AOA at the same rate as the engine placement increased their aerodynamic lift (at all given speed, no less), than this could result in a stable configuration. Maybe that's the case... (huh, yeah, maybe).
You are viewing this as "just put the trim down a bit" then the plane is now stable. I see it as "put the trim down a bunch to get the nose back down, cuz the pilot is an idiot." If the full amount of stabilizer overpowers the full range of flaps, and MCAS does half that amount per firing, I see that as a huge amount of trim.
Also, if you suggest the full amount of the elevator can't recover (let alone maintain) the plane with the stabilizer in a "normal" position when in an AOA where the 737 NG is happy to be flown and controllable, then your idea of what Boeing has done is way worse than what I even imagine, lol. This is gone from greed to total insanity.
-
Wow, the same plane had the same incident the day before, and a pilot in the jump seat knew what to do and saved the plane:
Which means that only one pilot out of the seven who have actually experienced the flaw in real time (as opposed to the experts in this thread) knew what to do. Two, plus the quick-witted jump-seat pilot in the first instance, two in the first crash, and two in the second crash, makes seven.
Just wanted to point that out with respect to the pilot-error argument.
-
Obi_Kwiet
Thanks for trying to enlighten me, but I disagree with most of what you wrote there. And I understand (at least since the last couple days) the difference between the elevators and the horizontal stabilizers. We do not agree what instability means in this context.
If you manually just adjust the trim down, this makes the plane stable at only one exact AOA. This is great if you want to leave the plane exactly there, and baby sit it so it doesn't change. Operating in an unstable area means (to me) if you inadvertently let the plane's attitude drift slightly down, that amount of trim you dialed in is now too much, and the plane will nose down in increasing rate. And if the plane drifts up a little, it will not be enough, and the plane will nose up ever more increasing. Because this it is unstable. It's like you are correcting me with your definitions of stable vs instable. But when I say the same thing, you disagree.
You are viewing this as "just put the trim down a bit" then the plane is now stable. I see it as "put the trim down a bunch to get the nose back down, cuz the pilot is an idiot." If the full amount of stabilizer overpowers the full range of flaps, and MCAS does half that amount per firing, I see that as a huge amount of trim.
Also, if you suggest the full amount of flaps can't recover the plane with the stabilizer in a "normal" position when in an AOA where the 737 is happy to be flown and controllable, then your idea of what Boeing has done is way worse than what I even imagine, lol. This is gone from greed to total insanity.
These aren't "my" definitions of stability, they are "the" definitions of stability. Every aircraft has unstable system states. It doesn't matter, and it's not relevant to what we are discussing. We don't care that the aircraft will always return to level flight or remain in its current attitude if given no control inputs, because it won't. We care that the aircraft can always be recovered to safe level flight within a reasonable flight envelope that is maintained by the judgement of the pilot. Secondarily, we'd like to be able to do that in a climb without cutting power the the engine, but that's really just a "nice to have", and it's what MCAS gives you.
The degree of deflection that the MCAS can command is unnecessary and a design flaw.
You are trying to claim that because a full power, flaps up climb may not be able to be leveled out with the elevators alone, that the plane is somehow unsafe and irresponsible. Why? The pilot and flight computer have access to multiple system variables that will level the aircraft. Why must it be fully adjustable with only the elevator? This is just an arbitrary assertion with no real justification behind it.
-
These aren't "my" definitions of stability, they are "the" definitions of stability.
And I fully accept these definitions. And furthermore, I am applying these definitions to the real world, i.e. the plane. This is what engineers do. You want to state the definition of instability. Then say, "ok, forget about it. Now, let's talk about planes!"
You are trying to claim that because a full power, flaps up climb may not be able to be leveled out with the elevators alone, that the plane is somehow unsafe and irresponsible. Why? The pilot and flight computer have access to multiple system variables that will level the aircraft. Why must it be fully adjustable with only the elevator? This is just an arbitrary assertion with no real justification behind it.
Because... in order to get into a high AOA, I would assume you need to put the elevator UP? And going by your definition of stability you just wrote a few hours ago, in the original plane you would have to maintain some of this elevator up (or use trim) to even keep it there, else the AOA would decrease. But you say in the MAX, once you get the AOA up (to this same AOA), you would have to completely reverse the elevator to full down, but even this would not be enough by itself to prevent the plane from runaway flipping up and stalling...
So yeah, this sounds much worse than anything I ever imagined.
We don't care that the aircraft will always return to level flight or remain in its current attitude if given no control inputs, because it won't.
Yeah, it would be nice if our cars drove themselves. We have to steer them. Without cruise control, we have to press the gas pedal. But if we had to ride a knife edge where any deviation got increasingly worse, it would be impractical to drive a long distance. It might be nice to be able to say "Yeah, officer. I was doing 120, but my gas pedal is unstable! One second I'm doing 60, then 65, and then the next thing I know I'm doing 120!" Theoretically, it would be possible to ride a motorcycle or a bicycle with no rake on the front wheel. There are people with fast enough reflexes and innate balance they can ride a unicycle. But we put rake on the front steering fork so that the vehicle is self-stabilizing. It would be extremely taxing to have to constantly balance the vehicle.
You are trying to claim that because a full power, flaps up climb may not be able to be leveled out with the elevators alone, that the plane is somehow unsafe and irresponsible. Why? The pilot and flight computer have access to multiple system variables that will level the aircraft. Why must it be fully adjustable with only the elevator? This is just an arbitrary assertion with no real justification behind it.
Because the plane is supposed to be flyable without this stuff. What other "system variables" do you have access to by pressing the yoke? Now you want to press on the yoke while manually cranking the trim wheel for 20-30 seconds and also simultaneously pressing other buttons to modify "other system variables," and reducing thrust, all while monitoring air speed, pitch, and elevation, all because you wanted to use a part of the AOA range where with the NG, you just "pull up on the yoke a little?" And can you do this dance to keep the plane operating in this unstable region without accidentally tipping over into a stall, or alternately starting to nose down rapidly into the kind of flight you are not trying to do at this point in time? Please tell me when I get on a plane, my pilot doesn't need to be able to juggle while riding a unicycle. For 5 hours.
Please, if you can, tell me where I'm wrong, not that I'm wrong. We all know I'm wrong, already. Go ahead and tear this post apart.
-
I don't think it has beed posted yet, but Mentour Pilot demonstrates a MCAS runaway in a simulator. Note how the co-pilot does not have the strength to wind it back with his left hand. In the section before the clip he explains the dangers of trying to stop the trim wheels turning by hand.
https://youtu.be/xixM_cwSLcQ
-
When the WWII submarines wanted to dive quickly the captain called the crew to immediately run into the front section of the sub, and vice versa.
Maybe B will finally implement that procedure in their airplanes too. I bet the passengers will be pretty willing to follow such a command when the plane in a critical situation..
-
When the WWII submarines wanted to dive quickly the captain called the crew to immediately run into the front section of the sub, and vice versa.
Maybe B will finally implement that procedure in their airplanes too. I bet the passengers will be pretty willing to follow such a command when the plane in a critical situation..
Not at a >30' downward angle they wouldn't.
-
Mentour Pilot in the previously linked vid would not have tried that. He'd be calmly calling out to his copilot: "Memory item for crashing into the ocean." While copilot, who is more askeered of breaking a nail whilst trying (and failing) to crank the trim wheel than crashing, would realize he doesn't know that one, and glance at the manual wondering if that is listed under C for crashing.
I wonder if that was what it was like on that plane. Maybe on the first several problems. Maybe there were calmly leafing through the manual whilst the plane gradually slipped into the deep dive, unnoticed. I'm sure the last 30 seconds were not like that, though. On second thought, maybe it was... calm all they way to the end. Like the captain of the Titanic in the movies. On a big plane/ship, maybe everything happens in slow motion, and what is set in motion become inevitable/unstoppable way too far in advance to the point where the last 30 seconds is just resignation.
-
These aren't "my" definitions of stability, they are "the" definitions of stability.
And I fully accept these definitions. And furthermore, I am applying these definitions to the real world, i.e. the plane. This is what engineers do. You want to state the definition of instability. Then say, "ok, forget about it. Now, let's talk about planes!"
You are trying to claim that because a full power, flaps up climb may not be able to be leveled out with the elevators alone, that the plane is somehow unsafe and irresponsible. Why? The pilot and flight computer have access to multiple system variables that will level the aircraft. Why must it be fully adjustable with only the elevator? This is just an arbitrary assertion with no real justification behind it.
Because... in order to get into a high AOA, I would assume you need to put the elevator UP? And going by your definition of stability you just wrote a few hours ago, in the original plane you would have to maintain some of this elevator up (or use trim) to even keep it there, else the AOA would decrease. But you say in the MAX, once you get the AOA up (to this same AOA), you would have to completely reverse the elevator to full down, but even this would not be enough by itself to prevent the plane from runaway flipping up and stalling...
So yeah, this sounds much worse than anything I ever imagined.
Why? It's a flight characteristic. All planes with low slung engines will have more pitch up force on full throttle. The MAX just has a bit more. It's not like this is some sudden onset operating region where the dynamics change hugely. What happens is that you pull on back on the stick, and at full throttle, you'll notice stick pressure needed to maintain that AoA starts to lessen and invert. If you want to keep that AoA and full throttle, you need to push down, sometimes really hard. That's quite intuitive. The auto trim exists to help the aircraft maintain control input without physically exhausting the pilot. If you don't have trim, then you have to sit there and haul back super hard on the stick whenever you want to climb or descend. MCAS is just a special case of that for a specific situation.
Yeah, it would be nice if our cars drove themselves. We have to steer them. Without cruise control, we have to press the gas pedal. But if we had to ride a knife edge where any deviation got increasingly worse, it would be impractical to drive a long distance. It might be nice to be able to say "Yeah, officer. I was doing 120, but my gas pedal is unstable! One second I'm doing 60, then 65, and then the next thing I know I'm doing 120!" Theoretically, it would be possible to ride a motorcycle or a bicycle with no rake on the front wheel. There are people with fast enough reflexes and innate balance they can ride a unicycle. But we put rake on the front steering fork so that the vehicle is self-stabilizing. It would be extremely taxing to have to constantly balance the vehicle.
That's not what is happening with MCAS. It's not sudden and impossible react to. It's not an issue of reflexes. It's an issue of the fact that the plane is huge and hard to move. You need trim input because otherwise the control surfaces are physically too hard to move. It doesn't need to be automatic, but it is automatic to reduce pilot workload. All airliners already automatically adjust the trim for these exact reasons. MCAS is just one very specific case of automatic trim adjustment.
Because the plane is supposed to be flyable without this stuff. What other "system variables" do you have access to by pressing the yoke? Now you want to press on the yoke while manually cranking the trim wheel for 20-30 seconds and also simultaneously pressing other buttons to modify "other system variables," and reducing thrust, all while monitoring air speed, pitch, and elevation, all because you wanted to use a part of the AOA range where with the NG, you just "pull up on the yoke a little?" And can you do this dance to keep the plane operating in this unstable region without accidentally tipping over into a stall, or alternately starting to nose down rapidly into the kind of flight you are not trying to do at this point in time? Please tell me when I get on a plane, my pilot doesn't need to be able to juggle while riding a unicycle. For 5 hours.
Like I said before, flying with just the yoke would be exhausting in any airliner. So would manually cranking the trim wheel to reduce stick pressure. That's why they all have auto trim. It's not like the aircraft is super twitchy, it's more like driving a big antique buss with no power steering. It's slow and predictable, but physically hard to turn the wheel. MCAS is really only relevant during a very small portion of the flight during climb-out, because that's the only part of the flight where this would be an issue. Most of the flight is hands off with an auto-pilot keeping the course. Honestly, the "yoke jerk" to turn off auto trim seems like a bad idea to me. The yoke controls the ailerons and the elevators. It's a bit subjective, but I think it's better to keep distinct control surfaces attached to their separate interfaces.
-
Why? It's a flight characteristic. All planes with low slung engines will have more pitch up force on full throttle. The MAX just has a bit more. It's not like this is some sudden onset operating region where the dynamics change hugely. What happens is that you pull on back on the stick, and at full throttle, you'll notice stick pressure needed to maintain that AoA starts to lessen and invert. If you want to keep that AoA and full throttle, you need to push down, sometimes really hard. That's quite intuitive. The auto trim exists to help the aircraft maintain control input without physically exhausting the pilot. If you don't have trim, then you have to sit there and haul back super hard on the stick whenever you want to climb or descend. MCAS is just a special case of that for a specific situation.
Obi, you did not understand what I was talking about.
1. I am aware that the MAX induces more nose up under throttle. And they way I have read it is not "a bit more," it's actually "quite a bit" more. And yet, this is not what I'm referring to in my last couple of posts between us.
2. There is an additional aerodynamic problem that is caused by the larger engines. The plane was designed to be aerodynamically efficient and stable with the original engines. As AOA increases, the belly of the plane starts to increasingly get exposed to the oncoming air. And these larger engines, which are placed farther forward, are now getting hit at an angle. They are no longer just thrusting the plane. They cause lift and drag simply by their aerodynamic shape. But due to their farther forward position, the lift is not acting at the center of mass of the plane, anymore. It is closer to the nose and is creating a twisting force, causing the nose to pull up. Due to the higher engine placement, the drag is no longer acting below the wing as much, which should be counteracting this force, more, in the original placement.
3. In fact, the aerodynamic lift from the engines is acting on the plane through the wings. So this is increasing the torque on the wings (in addition to the normal loading and effect of engine thrust) and might induce a small fraction of an inch more than the normal twist to the wings, increasing the wings' AOA. This is certainly true (as an average, and to an engineer) on some level. Everything has flex. Whether it is significant or not, who knows.
4. Unlike the nose up effect that is caused by throttle, this nose up effect induced by the aerodynamics is not significant at lower AOA. But it increases ever more at higher AOA. This is what makes the high AOA reagion unstable on the MAX. The engine effect would be more static and controllable, as you say, by the pilot, simply by adding trim based on thrust. Unstable doesn't mean unflyable. If it is minor, it would just mean more manual labor/tweaking/monitoring to keep the plane in this region. Since it is probably relatively close to a stall, this might make it unsafe.
4b. Whenever you have some effect (aerodynamic lift of the engine) which causes something else (nose up of the plane) that increases its own effect (the aerodynamic lift of the engines is now greater), this is what might be called a positive feedback loop. Unchecked, it causes some degree of instability. You can't completely negate/counter this dynamic variable with a static change (like setting trim to X).
5. MCAS does not adjust the trim when you change throttle. It reacts only to AOA. It therefore is not strictly there to counterbalance the effect of the throttle.
6. I might be wrong, but because the pilot makes trim adjustments for other reasons and for intentions unknown to the MCAS system, it would be impossible for MCAS to be able to dynamically and actively negate the aerodynamic effect of the engines without making some degree of unpredictability in handling to the pilot. This is why I believe the MCAS is more like a "Saw Stop." I would guess it acts more like a last ditch anti-stall, despite how Boeing wants to classify it. Also, to actively/dynamically negate the aerodynamic effect of the engines, MCAS would have to be keeping track of the changes it makes; which this either isn't the case (since it is known to be able to repeatedly fire, indefinitely), or there was an actual bug (whether coding or design oversight) in the original implementation.
6b. For active electronic dynamic stability to work best, with the fewest compromises, IMO, requires fly-by-wire. Airbus. F16. W/e. The computer has to be able to take the user input and decide how to implement that in the moment (mixing this in with the juggling), so that the pilot gets a consistent response. There is a huge amount of work and risk and expense to get the response tuned/refined to be efficient to human pilots... because someone has to test it.
I state all these things like facts, but it is just what has been spread in the internet news. And I may be inferring some of it incorrectly. As for the physics/aerodynamics, full disclosure; I'm not an engineer in the state of Oregon, but I like to pretend I am, on the internet.
I'm sorry for the confusion you have had over this, thinking I'm talking about the engine thrust effect. And I thank you for adding your insights and for engaging my questions.
-
Why? It's a flight characteristic. All planes with low slung engines will have more pitch up force on full throttle. The MAX just has a bit more. It's not like this is some sudden onset operating region where the dynamics change hugely. What happens is that you pull on back on the stick, and at full throttle, you'll notice stick pressure needed to maintain that AoA starts to lessen and invert. If you want to keep that AoA and full throttle, you need to push down, sometimes really hard. That's quite intuitive. The auto trim exists to help the aircraft maintain control input without physically exhausting the pilot. If you don't have trim, then you have to sit there and haul back super hard on the stick whenever you want to climb or descend. MCAS is just a special case of that for a specific situation.
Obi, you did not understand what I was talking about.
1. I am aware that the MAX induces more nose up under throttle. And they way I have read it is not "a bit more," it's actually "quite a bit" more. And yet, this is not what I'm referring to in my last couple of posts between us.
2. There is an additional aerodynamic problem that is caused by the larger engines. The plane was designed to be aerodynamically efficient and stable with the original engines. As AOA increases, the belly of the plane starts to increasingly get exposed to the oncoming air. And these larger engines, which are placed farther forward, are now getting hit at an angle. They are no longer just thrusting the plane. They cause lift and drag simply by their aerodynamic shape. But due to their farther forward position, they are not lifting at the Center of Mass of the plane. They provide a twisting force, causing the nose to pull up.
3. In fact, the aerodynamic lift from the engines is acting on the plane through the wings. So they are increasing the torque on the wings and might induce a small fraction of an inch more than the normal twist to the wings, increasing the wings' AOA. This is certainly true (as an average, and to an engineer) on some level. Everything has flex. Whether it is significant or not, who knows.
4. Unlike the nose up effect that is caused by throttle, this nose up effect induced by the aerodynamics is not significant at lower AOA. But it increases ever more at higher AOA. This is what makes high AOA unstable on the MAX. The engine effect would be more static and controllable, as you say, by the pilot, simply by adding trim based on thrust.
5. MCAS does not adjust the trim when you change throttle. It reacts only to AOA. It therefore is not strictly there to counterbalance the effect of the throttle.
I state all these things like facts, but it is just what has been spread in the internet news. And I may be inferring some of it incorrectly.
I'm sorry for the confusion you have had over this, thinking I'm talking about the engine thrust effect.
a "positive feedback" from the bigger engine nacelles at high AOA is also my understanding of the issue
so the MCAS is there to prevent something simliar this:
https://youtu.be/g8XxQkXCmsU?t=11s
https://youtu.be/e21ZjwZGjiQ?t=25s
-
First link, i give a 9. But, wow, that second link is a perfect 10. Height, distance, and oodles of style.
-
LIVE: Senate airline safety hearing
https://www.youtube.com/watch?v=HA_By6v35lM (https://www.youtube.com/watch?v=HA_By6v35lM)
-
LIVE: Senate airline safety hearing
The amount of lies in those hearings is off the charts even when measured in dB
-
When you have a bad sensor, both the flight control software and the pilot are being lied to and make mistakes. Never mind Boeing's shit MCAS disaster.
I would add AI, something that models the aircraft using all available sensor data BUT only makes a recommendation to the pilot. All the machine intelligence in the world, but no overriding the pilot's ultimate authority. That just leaves crashes attributable to human error, but reduced due to the AI offering a suggestion.
This is highly relevant to each of us, soon there will be self-driving vehicles for all.
As an example with a self-driving vehicle, do you risk roll-over turning sharp OR hit the tree? Traction is unknown, ice, rain etc.
"Envelope protection" would not let the steering wheel get cranked to avoid the tree, because the prediction is vehicle roll-over. So you hit the tree.
I don't see either philosophy being so great.
-
Why? It's a flight characteristic. All planes with low slung engines will have more pitch up force on full throttle. The MAX just has a bit more. It's not like this is some sudden onset operating region where the dynamics change hugely. What happens is that you pull on back on the stick, and at full throttle, you'll notice stick pressure needed to maintain that AoA starts to lessen and invert. If you want to keep that AoA and full throttle, you need to push down, sometimes really hard. That's quite intuitive. The auto trim exists to help the aircraft maintain control input without physically exhausting the pilot. If you don't have trim, then you have to sit there and haul back super hard on the stick whenever you want to climb or descend. MCAS is just a special case of that for a specific situation.
Obi, you did not understand what I was talking about.
1. I am aware that the MAX induces more nose up under throttle. And they way I have read it is not "a bit more," it's actually "quite a bit" more. And yet, this is not what I'm referring to in my last couple of posts between us.
2. There is an additional aerodynamic problem that is caused by the larger engines. The plane was designed to be aerodynamically efficient and stable with the original engines. As AOA increases, the belly of the plane starts to increasingly get exposed to the oncoming air. And these larger engines, which are placed farther forward, are now getting hit at an angle. They are no longer just thrusting the plane. They cause lift and drag simply by their aerodynamic shape. But due to their farther forward position, they are not lifting at the Center of Mass of the plane. They provide a twisting force, causing the nose to pull up.
3. In fact, the aerodynamic lift from the engines is acting on the plane through the wings. So they are increasing the torque on the wings and might induce a small fraction of an inch more than the normal twist to the wings, increasing the wings' AOA. This is certainly true (as an average, and to an engineer) on some level. Everything has flex. Whether it is significant or not, who knows.
4. Unlike the nose up effect that is caused by throttle, this nose up effect induced by the aerodynamics is not significant at lower AOA. But it increases ever more at higher AOA. This is what makes high AOA unstable on the MAX. The engine effect would be more static and controllable, as you say, by the pilot, simply by adding trim based on thrust.
4b. Whenever you have some effect (aerodynamic lift and drag of the engine) which causes something else (nose up of the plane) that increases its own effect (the aerodynamic lift and drag of the engines is now greater), this is what might be called a positive feedback loop. Unchecked, it causes some degree of instability. You can't completely negate/counter this dynamic variable with a static change (like setting trim to X).
5. MCAS does not adjust the trim when you change throttle. It reacts only to AOA. It therefore is not strictly there to counterbalance the effect of the throttle.
I state all these things like facts, but it is just what has been spread in the internet news. And I may be inferring some of it incorrectly.
I'm sorry for the confusion you have had over this, thinking I'm talking about the engine thrust effect. And I thank you for adding your insights and engaging my questions.
2. From a stability perspective, the NG and the Max are apparently no different when it comes to getting into a stall. You have to be very careful on the throttle and push the nose back down on both models. The MCAS is there in case you make a mistake and get into a stall, you need some help from the trim to push the nose down and smooth out the stall. (If you keep the nose up, the stall will eventually correct itself, but it will be more violent. I doubt the engines are powerful enough to keep the nose up forever.) See this: https://youtu.be/TlinocVHpzk?t=969 (https://youtu.be/TlinocVHpzk?t=969)
3. The Max has new wings that are designed to withstand a flight envelope that is far greater than is safe for the passengers. Structural failure shouldn't be a concern here.
4. These are all part the same effect and they are present on all models. It's just stronger after the stall has taken place on the Max due to engine thrust and location. You still have to be very careful on the throttle on the NG to avoid the stall for all of these reasons. In the NG, I think the effect was controllable using the elevators alone. The MAX needs a bit of trim in addition, and if the pilot is busy trying to fix a stall, it's better if he/she doesn't have to manually fuss with the trim at the same time. That's what the auto trim system is for. The first part of that video I linked explains it all.
4b. You say that you can't negate a positive feedback loop with a static change, but this isn't correct. If the position of the engines is what causes the problem in the first place, that's a static change to the aerodynamics of the aircraft. If a static change can cause a feedback loop, it can stop it. But we aren't trying to make the aircraft stable, we just want to make it possible for the pilot to level the aircraft out with the control yoke.
5. MCAS only activates what certain AoA, throttle, flaps, and I think airspeed conditions are met.
So, yes, there is a small operating region where the angle of attack will increase until the aircraft stalls. This is present on both model of the 737. My point isn't that this isn't true, but that it's not important. As I said before, all aircraft have unstable regions of of operation. Instability is only an issue for two reasons. One, the instability may such rapid control responses that the pilot cannot keep up with them. An extremely unstable aircraft might exceed the ability of the control surfaces to respond quickly enough to stabilize the aircraft, making it impossible for even a computer to fly it. Two, even if a person can keep up with the instability, it may be tedious to do for a long period of time. The fact that the 737 Max has an unstable operating region simply doesn't matter, and it's not the issue we are discussing.
a "positive feedback" from the bigger engine nacelles at high AOA is also my understanding of the issue
so the MCAS is there to prevent something simliar this:
https://youtu.be/g8XxQkXCmsU?t=11s
https://youtu.be/e21ZjwZGjiQ?t=25s
No, I don't think so. The engines would have to be absurdly powerful to do that. Once the AoA gets too high, the airspeed will drop, and the airflow won't be enough to sustain the AoA. You'll just end up with a much worse stall.
-
If I got this right, after al, this boils down to a philosophical question:
Should the final decision be left to a human, or to a machine?
Yep, that's a burning question, like the stupid trolley question in the philosophy 101 classes. I know the industry already commited to 'give the final decision to the machine', but if you ask me, this is a wrong approach no matter the statistics.
But the aircraft industry (as a whole, at least) didn’t do that. In the 737 MAX, like in all 737s, there is a switch right on the center console to disable the motor for stabilizer trim, the motor used by the thumb controls on the yoke, the autopilot, and in the MAX, MCAS. Flip the switch to “disable” and the pilots are in full manual (fully mechanical, by cable) control of stabilizer trim, by turning the stabilizer trim wheels with their pop-out cranks. (It’s puzzling that the pilots in these two flights didn’t do this, since it’s standard procedure when the stabilizer trim is acting up, even if you don’t know why it’s acting up.)
Generally speaking, Boeing leans more towards “give humans final authority” than Airbus does, but the differences between the two camps are fairly small, all things considered. (The vast majority of automated systems on an Airbus can be overridden, and AFAIK every automated system on a Boeing can.)
-
I would add AI, something that models the aircraft using all available sensor data BUT only makes a recommendation to the pilot. All the machine intelligence in the world, but no overriding the pilot's ultimate authority. That just leaves crashes attributable to human error, but reduced due to the AI offering a suggestion.
That’s pretty much what all the safety systems already do. There’s always (or, in some Airbuses, almost always) a way to override things.
People don’t seem to understand that cockpit automation isn’t all-or-nothing, and that pilots don’t just spend their days twiddling their thumbs. They routinely fly manually, and the aircraft absolutely allow full manual control. It’s just that with so many things to keep an eye on, it makes sense to delegate as needed, and that’s what the various cockpit automation systems do. Want it to maintain level? Select that. Or autothrottle? Choose that. Navigation? Ok. But the pilot can take back authority over any or all of those things if and when desired. (There have been a few crashes caused by a pilot inadvertently putting some system on the wrong setting, such that they thought it was doing one thing, but was actually doing another...)
-
2.
The MCAS is there in case you make a mistake and get into a stall, you need some help from the trim to push the nose down and smooth out the stall.
Interesting. This is what I guessed it probably did. Despite Boeing just now in a senate hearing denying it. Senator Sinema (lol) asked about the MCAS anti-stall, and was corrected by the Boeing execute that it is NOT an anti-stall. Whether that's the case in practice or just legal CY6, who knows.
But your answer is completely ignoring the aerodynamic lift/drag which has been discussed in the news.
3. This was just me being detailed. As I say, flex is present in all things. The idea was not that it was dangerous to the wings, I'm just highlighting the direction of torque would tend towards more AOA of the wings in this secondary (and probably trivial and stupid to mention) way.
4. I don't like you you said that. But I see what you mean. If when you set the trim down far enough, it also increases in drag/effect at increasing AOA roughly same amount as the engine increases in lift, then it could make this region stable. Good point.
No, I don't think so. The engines would have to be absurdly powerful to do that. Once the AoA gets too high, the airspeed will drop, and the airflow won't be enough to sustain the AoA. You'll just end up with a much worse stall.
I think you are missing the point of this. Langwidt is highlighting the aerodynamic effect of the engines. When level, no effect. As the front of the car lifts, the lift increases. And like the engines on the MAX, this lift isn't centered under the COG, so the car noses up. Indy car needs to get together with Boeing to add MCAS* to the car, so instead of flipping it can do a Mario jump.
*Oh irony. Boeing initially snuck MCAS onto the plane without even disclosing it to its customers. And now "MCAS" is a permanent part of my vocabulary.
-
Lots of detailed info from Juan.
https://www.youtube.com/watch?v=Ora-yZCTtpg (https://www.youtube.com/watch?v=Ora-yZCTtpg)
-
I think you are missing the point of this. Langwidt is highlighting the aerodynamic effect of the engines. When level, no effect. As the front of the car lifts, the lift increases. And like the engines on the MAX, this lift isn't centered under the COG, so the car noses up. Indy car needs to get together with Boeing to add MCAS* to the car, so instead of flipping it can do a Mario jump.
those were Le Man cars, they now have big holes in the fenders bleeding the air under that car so bottom doesn't create lift
NASCARS has a system of flaps on the roof of car that pops up if the car goes sideways or backwards spoiling the lift that previous tended to flip the cars, mechanical MCAS if you will ;)
-
Ever since you said you were deliberately presenting media-filtered layman explanations as fact, while also admitting you knew they were technically wrong, I've lost all urge to correct you. You're basically trolling us at this point.
-
^I don't know if that was directed at me, or not. But that's the point. I'm not an authority, and I don't want anyone should take me seriously. It's just a discussion.
But... I came here because I had a revelation.
I'm an idiot.
4b. You say that you can't negate a positive feedback loop with a static change, but this isn't correct. If the position of the engines is what causes the problem in the first place, that's a static change to the aerodynamics of the aircraft. If a static change can cause a feedback loop, it can stop it.
Of course you are right.
Where I went wrong:
I stumbled over the problem that the stabilizer can't possibly have the same (but opposite) effect that the engines aerodynamics have by mere coincidence. But it doesn't matter. As long as the stabilizer is set to the point where its own counter effect is at least as much, if not a bit greater, than the lifting effect of the engines @ something slightly under the maximum effective AOA for the plane (for safe margin), then the plane would at least be stable near maximum AOA.
The MCAS is a dynamically acting solution. It's just that it has a 1 bit resolution response. We have "hi AOA" and "lo AOA". And then analog takes over from there.
Depending on the shape of the function graphs of the two opposing forces, this might result in the plane acting differently at this transition point. From lo to hi, there would be a change, like the step in a "logarithmic pot" [which is typically just 3 linear sections, connected, to approximate the actual curve]. There would be the distinct and steep downward net, here, over 10 or so seconds with a binary outcome.
1.But after powering through it with the elevators, it could drop and get closer to balanced. Even if the sum force temporarily trended to net positive at some point, it would be ok, as long as it is net negative, again, by the time the max AOA is reached.
2.converserly, if the pilot didn't fight through it, and just let the AOA drop, the MCAS would "deactivate" and put the trim back up for 10 seconds. (Not in the news, but now I simply assume Boeing is doing it like this.... hm, which means software bug is definite possibility to explain refiring. So this is good... and bad.... I mean the thing only has to remember two states in this hypothetical model).
But yeah, I'm an idiot. This is how buggy software gets written and later fixed after non-idiots test it.
-
My point isn't that this isn't true, but that it's not important.
This is a point that the Media abuse incessantly.
The fact that they can write about a particular subject is all that matters - its relevance to the overall situation is ignored. The reason is quite obvious - sensationalism sells. It's all about the money.
In fact, how the Media operate has a lot in common with some of the scams we have seen... A kernel of truth that is embellished and perverted, all for the sake of a buck.
-
I'd argue that it's more a systems level bug than a software bug. The unlimited reactivation of MCAS was to spec, AFIK, it's just that that's dangerous and pointless.
I'm really annoyed at what a sloppy job of reporting the media does. You really have to dig to understand what is going on, and the media are just straight up wrong so much of the time. Unfortunately, that means that the public's takeaway is inaccurate and misdirected. I think we may have some interesting takeaways from all this on a system design and review process perspective, but everyone is shouting for some big shot to take the fall. Honestly, I doubt if anyone high up in the company knew about MCAS in any real detail.
-
As previous mentioned from Nasa database( pages ago) pilots had little or no training on MCAS now its reported flight crew manual mention MCAS only once in glossary, Boing refuses to reply! Oh the drama, death, pain, money, fat lady not even dress'ed up yet while Boing apologists and top management on front row starts to sweat !
https://www.youtube.com/watch?v=HxnanW-ZLPg (https://www.youtube.com/watch?v=HxnanW-ZLPg)
Senator Blumenthal refers to NASA pilot database and request personal parachute if to fly with 737MAX. :scared:
https://www.youtube.com/watch?v=96m6bNjkAFc (https://www.youtube.com/watch?v=96m6bNjkAFc)
-
Pilot talks about the 737Max problems in its DNA and how pilots dont understand MCAS and the planes behavior.
https://www.youtube.com/watch?v=vZbCz5oPXeg (https://www.youtube.com/watch?v=vZbCz5oPXeg)
-
-Yes, there's a flaw in the software.
-Yes, the AoA sensor may have failed.
-Yes, Boeing had not provided yet any fix for these known defects, five months after the Lion Air 610 crash.
But,
That said, this pdf put out by Boeing on 6th November 2018 explains very clearly the problem and a fix/workaround:
TBC-19-Uncommanded-Nose-Down-Stab-Trim-Due-to-AOA
http://www.avioesemusicas.com/wp-content/uploads/2018/10/TBC-19-Uncommanded-Nose-Down-Stab-Trim-Due-to-AOA.pdf (http://www.avioesemusicas.com/wp-content/uploads/2018/10/TBC-19-Uncommanded-Nose-Down-Stab-Trim-Due-to-AOA.pdf)
In the event of erroneous AOA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released. Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC.
Why did the ET flight 302 pilots not do that?
Is it possible that they had not seen/read/known about that pdf?
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=689658;image)
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=689664;image)
-
-Yes, there's a flaw in the software.
-Yes, the AoA sensor may have failed.
-Yes, Boeing had not provided yet any fix for these known defects, five months after the Lion Air 610 crash.
But, That said, this pdf put out by Boeing on 6th November 2018 explains very clearly the problem and a fix/workaround: Why did the ET flight 302 pilots not do that? Is it possible that they had not seen/read/known about that pdf?
You forgot to mention the certification process sidestepping and now the added safety features "ala carte" debacle!
Precisely this bulletin note did "not" go into the flight crew manual as explained/excused in one of above videos, combine that with no training,and there is a result.
1: WHERE is this bulletin supposed to be if not in the flight crew manual?
2: Are a pilot supposed to memorize everything and if do but later forgets or not not able to, the license withdrawn?
3: How many armchair pilots here remembers every fix and workarounds for STM32 devices published in errata sheets
and what about all those undocumented bugs STM32 have who popp's up when you least expect it?
This bulletin says only during manual flight, Juan above says only during autopilot engagement, cant even be turned off
during take off. This mess clearly tells why Ethiopians went to the French. All about the faff FFA and Boing is doing and not doing.
This whole story have streaks of not pilot failure, nor engineering failure(-softbugs) rather middle and top management failure.
-
The thing is, the checklist for runaway stabilizer trim is something that all 737 pilots are trained for, and is required to be known by memory. So while MCAS adds another point of failure, going through the standard 737 runaway stabilizer trim checklist would still disable MCAS and return stabilizer trim authority to the pilots. Even without knowing about MCAS, the pilots should still have been able to recover, if they acted quickly.
Note that the first item of this checklist is to disable autopilot. But this would already be the case, since MCAS only applies to manual flight. When autopilot is on, the autopilot, and not MCAS, has authority over the stabilizer trim.
-
This bulletin says only during manual flight, Juan above says only during autopilot engagement, cant even be turned off during take off.
Manual flight is any time the autopilot is disengaged while flying.
When you're already on the ground, and something that should be working is not, then one should NOT take off and have the aircraft serviced instead. The automatic takeoff procedure merely enforces that policy, and Juan was reflecting that reality. I'm sure that he COULD get the aircraft off the ground manually if the alternative was worse (tidal wave incoming or something), but otherwise the actual policy is the same...don't fly with a known problem. (The exception would be pre-authorized ferry flights for maintenance with no passengers.)
Imagine how loud YOU would be screaming if someone knowingly took off without EVERYTHING working and then crashed? You do realize that's exactly what you just demanded, right?
-
Aircraft routinely begin flights with things out of order. Some faults automatically ground an aircraft, others can be deferred.
-
Aircraft routinely begin flights with things out of order. Some faults automatically ground an aircraft, others can be deferred.
I'm aware of that, but it was sorta besides the point, since the automatic trim system has never been one of those exceptions to my knowledge. Nor would that fact have anything to do with how loud MT would rant when a crash is involved.
Even the authorized exceptions have to be documented and signed off before the aircraft leaves the ground if it has anything to do with the flight or power systems. Nonworking passenger wifi or a broken coffee pot won't matter much, however.
-
Note that the first item of this checklist is to disable autopilot. But this would already be the case
You would still go through the checklist from the top. If you saw Mentour Pilots video demonstration during simulation, it's a bit comical how formal it is. So in their 40 seconds, they would potentially be verbalizing each item, starting from the beginning.
So
1. "Memory items for runaway stabilizer"
2. "Memory item 1:Turn off the autopilot." Memory item 1 is not "If the autopilot is already off, skip to item 2"
3. The pilots would turn off autopilot
4. Then they would monitor for the result. And since MCAS is intermittent, "the result" may initially appear to be perfectly satisfactory.
You are supposed to monitor the result. You are NOT supposed to proceed to memory item 2, blindly. And if the result is satisfactory, you are supposed to stop.
That can waste a lot of time out of the 40 seconds the pilots had.
In the first incident with Indonesian Air/Jakarta, the pilots did the dance for 10 minutes, or something. I have not seen any detailed info for the Ethiopian Air crash. Just that the news said they had 40 seconds. And Ethiopian Air stated all their MAX pilots received MAX specific updated training, including the hiterto optional simulation in the interim between the Jakarta crash and this one.
Now, how pilots actually do this may be totally different in the plane. But even with the updated training, the solution may be insufficient? I'll bet if the pilot skips the first step, it's an automatic fail, in training. If you were to go "by the book," the book might kill you? I think that could be considered an insufficient solution. I imagine that strictly following procedure/protocol is supposed to be sufficient.
The protocol is there, presumably to prevent pilots from jumping to incorrect conclusions. There could be good safety reasons, statistically, that we want pilots that blindly follow protocol in this kind of situation. There could be financial pressures, as well. If the pilot cuts stab trim out of order, then he may not be allowed to later say "oops, my bad" and turn it back on. And he may have to divert the plane? Just speculating out loud. In this case, the pilot had already requested to return to the airport of departure, so he was already past that.
-
well you can talk all technical all protocol you like, they can do any cover up they like. for me the simple fact is, at this age, boeing is stupid enough not to put AI, ie just to let a commercial airplane to dive at military fighter jet grade of dive down, or overwhelming pilots with pages of manual and plethora of gauges and controls of the past centuries while the plane is tumbling down. not sure if its mentioned in this 29 pages thread, another 737 mishap on the best flight brand... https://edition.cnn.com/2019/03/10/africa/ethiopia-airline-crash-nairobi-intl/index.html imho all 737 shoud be called back, it hasnt happened before with older models, just think sensibly no need super complicated discussions just to find an answer/solution. pitot tubes failed? give me $5 gyro an accelerometer and an arduino and i'll fix that for you. call me ignorant or a fool if you like.
-
well you can talk all technical all protocol you like, they can do any cover up they like. for me the simple fact is, at this age, boeing is stupid enough not to put AI, ie just to let a commercial airplane to dive at military fighter jet grade of dive down, or overwhelming pilots with pages of manual and plethora of gauges and controls of the past centuries while the plane is tumbling down. not sure if its mentioned in this 29 pages thread, another 737 mishap on the best flight brand... https://edition.cnn.com/2019/03/10/africa/ethiopia-airline-crash-nairobi-intl/index.html imho all 737 shoud be called back, it hasnt happened before with older models, just think sensibly no need super complicated discussions just to find an answer/solution. pitot tubes failed? give me $5 gyro an accelerometer and an arduino and i'll fix that for you. call me ignorant or a fool if you like.
hm.., how are you going to measure air speed with a gyro/accelerometer?
-
Any sort of automation falls apart as soon as you have one or more bad sensors feeding it the data. This is why you have human pilots in the cockpit ready to take over manually at any point. Jumping to conclusions and saying "oh this is easy, just have the software automatically do X, Y and Z!" is how you end up having discussions like this thread.
Personally I think pilots should be encouraged to hand fly much more often than they do. Too much reliance on automation takes people out of the loop and encourages the mind to wander.
-
Personally I think pilots should be encouraged to hand fly much more often than they do. Too much reliance on automation takes people out of the loop and encourages the mind to wander.
I agree, but in today's world...
Management: You want employees to actually have fun on the job? We pay them to be miserable.
Seriously, though, as Boeing CEO has stated, and which I'm sure is true, Boeing, and probably the industry as a whole, is driven by data. Sure, these crashes might have been avoided if X, Y, or Z. But overall, things are done the way they are because it's the statistically safest way we currently know about... And venturing into the unknown on a hunch can produce much worse results in a hurry.
There are probably a lot of things about the planes we get on that we have no clue about, nor do we care. It's interesting how suddenly we all want to know about MCAS. I wonder if there are trade secrets (or even matters of national security) why Boeing can't spell out MCAS, completely. Of course, now, there are also legal reasons.
-
hm.., how are you going to measure air speed with a gyro/accelerometer?
given on condition of pitot tube failure (air speed measurement) and autopilot activated.
1) make sure airplane level (gyro and magnetometer)
2) altitude decreasing? or stall detection from accelerometer? increase engine speed and flap, aileron etc to appropriate position.
3) warning led to let pilot approve turning back or emergency landing to nearest site.
measure something with redundancy backup unit is better than measure nothing. otoh on manual mode, do not let pilot do stupid thing like miitary jet fighter acrobatic, (i saw youtube investigation that the pilot let his kid playing with the wheel :palm:) AI will take over if pilot proved incapable or imminent crash is detected. any other questions? ;)
-
hm.., how are you going to measure air speed with a gyro/accelerometer?
given on condition of pitot tube failure (air speed measurement) and autopilot activated.
1) make sure airplane level (gyro and magnetometer)
2) altitude decreasing? increase engine speed and flap, aileron etc to appropriate position.
3) warning led to let pilot approve turning back or emergency landing to nearest site.
on manual mode, do not let pilot do stupid thing like miitary jet fighter acrobatic, (i saw youtube investigation that the pilot let his kid playing with the wheel :palm:) AI will take over if pilot proved incapable. any other questions? ;)
Remind me to never be anywhere an aircraft you design is in the air. Your simplistic view is deadly.
Let's just take ONE aspect of this statement:
2) altitude decreasing? increase engine speed and flap, aileron etc to appropriate position.
With no indication of air speed, you could find the aircraft in an overspeed situation where the wings could literally get ripped off the fuselage.
-
Let's just take ONE aspect of this statement:
2) altitude decreasing? increase engine speed and flap, aileron etc to appropriate position.
With no indication of air speed, you could find the aircraft in an overspeed situation where the wings could literally get ripped off the fuselage.
so just let the plane do military dive, fine.
-
Note that the first item of this checklist is to disable autopilot. But this would already be the case
You would still go through the checklist from the top. If you saw Mentour Pilots video demonstration during simulation, it's a bit comical how formal it is. So in their 40 seconds, they would potentially be verbalizing each item, starting from the beginning.
So
1. "Memory item runaway stabilizer turn off autopilot"
2. "Memory item 1:Turn off the autopilot." Memory item 1 is not "If the autopilot is already off, skip to item 2"
3. The pilots would turn off autopilot
4. Then they would monitor for the result. And since MCAS is intermittent, "the result" may initially appear to be perfectly satisfactory.
You are supposed to monitor the result. You are NOT supposed to proceed to memory item 2, blindly. And if the result is satisfactory, you are supposed to stop.
That can waste a lot of time out of the 40 seconds the pilots had.
In the first incident with Indonesian Air/Jakarta, the pilots did the dance for 10 minutes, or something. I have not seen any detailed info for the Ethiopian Air crash. Just that the news said they had 40 seconds. And Ethiopian Air stated all their MAX pilots received MAX specific updated training, including the hiterto optional simulation in the interim between the Jakarta crash and this one.
Now, how pilots actually do this may be totally different in the plane. But even with the updated training, the solution may be insufficient? I'll bet if the pilot skips the first step, it's an automatic fail, in training. If you were to go "by the book," the book might kill you? I think that could be considered an insufficient solution. I imagine that strictly following procedure/protocol is supposed to be sufficient.
The protocol is there, presumably to prevent pilots from jumping to incorrect conclusions. There could be good safety reasons, statistically, that we want pilots that blindly follow protocol in this kind of situation. There could be financial pressures, as well. If the pilot cuts stab trim out of order, then he may not be allowed to later say "oops, my bad" and turn it back on. And he may have to divert the plane? Just speculating out loud. In this case, the pilot had already requested to return to the airport of departure, so he was already past that.
I never said anything about skipping checklist steps. Literally the point of a checklist is to GO THROUGH EACH ITEM.
I saw the Mentour demo long before my reply above, and yeah, it’s formal, but it would still get you through it fast.
-
Personally I think pilots should be encouraged to hand fly much more often than they do. Too much reliance on automation takes people out of the loop and encourages the mind to wander.
I agree, but in today's world...
Management: You want employees to actually have fun on the job? We pay them to be miserable.
It is my understanding that airlines do, in fact, encourage routine manual flying for precisely this reason. Many potential autopilot features (like auto-land) exist but are essentially never used.
The media perpetuates the myth that pilots don’t fly any more and just baby the autopilot in case it ever goes wrong, but this plain and simply isn’t true.
-
I never said anything about skipping checklist steps.
Sorry, I didn't say you did. I was just making a point that even though they might think autopilot is off, that's where they might start.
I think 40 seconds is cutting it pretty close if you watch how long that takes.
The airline stated their faith in Boeing planes; they also stated their pilots received all updated training. This certainly suggests there is still a problem that is beyond training/knowledge.
Boeing must know more about the crash, else I don't see how they can properly fix a problem that "isn't there." They've apparently already fixed the "non-problem" and have "tentative" FAA approval.
With 300 wrongful death suits on the line and billions in business, who knows what version of the truth we well ever get.
-
Let's just take ONE aspect of this statement:
2) altitude decreasing? increase engine speed and flap, aileron etc to appropriate position.
With no indication of air speed, you could find the aircraft in an overspeed situation where the wings could literally get ripped off the fuselage.
so just let the plane do military dive, fine.
Without an indication of air speed, you are just trading one disaster for another. Not smart.
-
you dont get me. dont trade it if you like, just let the disaster happens, fine with me. drones flew, no pitot tubes. oh i forgot, drone is different.
-
You don't get me. Any so-called "solution" isn't a fix when it introduces other risks.
Edit: BTW - it was you who was doing the trading - but you don't seem to realise that.
-
Mechatrommer is just making a general point. Nitpicking his post is stupid.
I just have to love it when the pilot police show up to demonstrate their knowledge of stupid-shit-no-one-cares-about. (When it's not germane to the point).
Of course an accelerometer would be useful if the pitot tubes went out. At least it could tell the pilot an continuing approximation of his air speed based on the last valid readings. And it could be fairly accurate for at least some duration. This would be highly useful if the pilot hadn't happened to be watching his airspeed at the time of sensor malfunction. Maybe it could also display a second figure, increasing over time/conditions, to let the pilot know how much salt to take with that reading.
GPS plus elevation and pitch could also be used for some ballpark figure, at least.
It seems bizarre that a failed pitot tube can result in AF447. The pilots can't even tell they're in a stall. And even after the sensor thaws and works perfectly fine, again, more than a minute before they could have saved the plane, they just didn't trust it.
With some backup that said: "yes.... your super low airspeed reading sounds right to me, too" that could have changed the outcome.
Human beings are apparently completely incapable of estimating airspeed devoid of visual reference. Any sort of backup might be useful.
-
You don't get me. Any so-called "solution" isn't a fix when it introduces other risks.
yeah like what boeing did to their new invention 737...
Edit: BTW - it was you who was doing the trading - but you don't seem to realise that.
i know but who am i to enforce that? you dont want my piece of advice is fine. what i was saying is if...... crash is imminent. rather that doing nothing. and most importantly, this kind of fault never happening before, so why they insist on new training scheme? this is just cover up of their mistake. i believe a total callback will put scar into their reputation, or the fear of bankruptcy paying compensation to the families. nuts.
Of course an accelerometer would be useful if the pitot tubes went out. At least it could tell the pilot an continuing approximation of his air speed based on the last valid readings. And it could be fairly accurate for at least some duration. This would be highly useful if the pilot hadn't happened to be watching his airspeed at the time of sensor malfunction. Maybe it could also display a second figure, increasing over time/conditions, to let the pilot know how much salt to take with that reading.
when someone put their brain ON (working), this is the comment. i hate typing too long english is not my strong point. and there will be always people to push you behind, but its ok for the sake of brainstorming. but then what? will boeing listen to this thread? if yes, i will elaborate in pages if i have to.
-
Sorry if I took your point too literally.
-
In the Mentour Pilot video it looked at if someone was at the simulator controls hitting/clicking on in the trim button every second or two. It has now been reported that each time MCAS triggers it runs/trims for 11 seconds. Which I assume would lead to a more intense situation.
-
Of course an accelerometer would be useful if the pitot tubes went out. At least it could tell the pilot an continuing approximation of his air speed based on the last valid readings.
Wow, so much stupid in one post. A gyro can't tell you airspeed. :palm:
I just have to love it when the electronics guys show up to demonstrate their complete ignorance of the-actual-topic-of-the-thread.
-
Of course an accelerometer would be useful if the pitot tubes went out. At least it could tell the pilot an continuing approximation of his air speed based on the last valid readings.
Wow, so much stupid in one post. A gyro can't tell you airspeed. :palm:
I just have to love it when the electronics guys show up to demonstrate their complete ignorance of the-actual-topic-of-the-thread.
who say it can? do you know what is "approximation"? nobody say it will be accurate for prolonged period. the bigger problem is when people dont read carefully and esp they dont have experience (http://youtube_dot_com/watch?v=_cwK0hrXgyI) (off topic link) :P if calling someone's post stupid, then i should be already in good hand :P
-
Hum, airspeed and grounspeed can be very different (wind and attitude) and unfortunally aircraft need airspeed to fly.
-
accelerometer cant measure both ground nor air (relative to plane) speed, its an inertial sensor, it can only measure change of its motion (v = u + at) so it can approximate motion by dead reckoning from the last known "good reading" for quite sometime. but maybe this is different discussion as the problem is buggy MCAS. maybe i was not clear enough combined with nitpicking... accelerometer combined with magnetometer can be used to estimate gravitation pull/direction or free fall condition and plane's attitude as well, this is available in any china $30 drones that has no eye, no GPS and no beacon no tringulation tower comm etc, the only thing left is the operator's stupidity. those $5 sensors are lacking in that 100 mills plane, no backup AI to prevent this (maybe FAA regulation to ban complete AI control?) to put injury to the insult, MCAS only cares about nose up stall, it doesnt care if the plane is in military dive nose down condition :palm: i dont see how is this acceptable. someone must have a good answer, the FAA if not Boeing.
-
On a sidenote here are some numbers on the economical impact.
TUI is a small airliner having 150 planes from which 15 are MAX that have been grounded.
If the MAX is allowed to fly in july the damage is 200 million euro, if allowed in september it is 300 million euro.
This is only one airliner, we are talking tens of billions of dollars total global I guess.
Dutch only so use google translate
https://www.nu.nl/economie/5816484/aan-de-grond-houden-boeing-737-max-kost-tui-200-miljoen.html (https://www.nu.nl/economie/5816484/aan-de-grond-houden-boeing-737-max-kost-tui-200-miljoen.html)
-
Magnetometers are prone to interference. Many AHRL modules nowadays don't use magnetic sensors anymore.
right, magnetometer needs to be constantly calibrated for true north under controlled condition if someone is rely to it as a compass. i guess thats why they are not fan of it and there's kalman filter to deal with unreliable sensors. from experience playing with "toyish grade" umanned vehicles/robot, a calibrated magnetometer can greatly improve dead reckoning compared to accelerometer alone on XY plane. although it may help on determining roll condition when airplane heading in Z axis (gravity), never tried that. both of this 6 axis accel and magnet sensors someone called them as complete attitude control. but this explanation is moot as i'll be surprised if boeing has no better attitude control than $30 one hung low drones.
-
The emerging 737 MAX scandal, explained. It’s more than bad software. (https://www.vox.com/business-and-finance/2019/3/29/18281270/737-max-faa-scandal-explained)
The FAA did not do their due diligence. The FAA is short on resources and pretty much let Boeing certify themselves figuring they would not cut corners and make an unsafe plane. Kind of reminds me of Chernobyl.
-
hmm wait for Comac C919 (https://en.wikipedia.org/wiki/Comac_C919) then we'll have more dive down occurrence pressure. Financial problem is not an excuse, 737 is bigger engines from predecessor, and that thing can dive up and down fine. this is just few lines of codes, imho.
-
The emerging 737 MAX scandal, explained. It’s more than bad software. (https://www.vox.com/business-and-finance/2019/3/29/18281270/737-max-faa-scandal-explained)
Hmm, I like the name of that newspaper... >:D
-
cbsnews.com: Relationship between FAA and Boeing under scrutiny after deadly crash. (https://www.cbsnews.com/news/faa-boeing-relationship-under-scrutiny-after-deadly-crash-2019-03-19/)
nytimes.com; After Boeing Crashes, Sharp Questions About Industry Regulating Itself (https://www.nytimes.com/2019/03/26/us/politics/boeing-faa.html)
-
The emerging 737 MAX scandal, explained. It’s more than bad software. (https://www.vox.com/business-and-finance/2019/3/29/18281270/737-max-faa-scandal-explained)
The FAA did not do their due diligence. The FAA is short on resources and pretty much let Boeing certify themselves figuring they would not cut corners and make an unsafe plane. Kind of reminds me of Chernobyl.
I like a lot of Vox's work, but not this piece. It seems to be kinda lacking in technical background and a bit too biased IMHO. Like… no, the engines aren't "too big" for this plane, they simply change its characteristics — the larger, higher engines simply magnify an effect that exists on all 737 aircraft.
-
On a sidenote here are some numbers on the economical impact.
TUI is a small airliner having 150 planes from which 15 are MAX that have been grounded.
If the MAX is allowed to fly in july the damage is 200 million euro, if allowed in september it is 300 million euro.
This is only one airliner, we are talking tens of billions of dollars total global I guess.
Dutch only so use google translate
https://www.nu.nl/economie/5816484/aan-de-grond-houden-boeing-737-max-kost-tui-200-miljoen.html (https://www.nu.nl/economie/5816484/aan-de-grond-houden-boeing-737-max-kost-tui-200-miljoen.html)
So is it better for everyone to let them fly sooner than later? :-//
-
I like a lot of Vox's work, but not this piece. It seems to be kinda lacking in technical background and a bit too biased IMHO. Like… no, the engines aren't "too big" for this plane, they simply change its characteristics — the larger, higher engines simply magnify an effect that exists on all 737 aircraft.
The way I understand it is that the engines being moved forward and up make this a totally new airplane which should have been subject to new certification but they went with the pretense that it is just a variation of the old 737 in order to simplify certification and gain time.
That is what I gather from everything I have read.
-
Hmm, I like the name of that newspaper... >:D
I have no idea what this is supposed to mean and I have no idea who Vox are or what their name is supposed to mean (other than "voice") so I went to Wikipedia and found out that they "target educated households with six-figure incomes and a head of house less than 35 years old."
I hope I am not accused of impersonating something I am not.
-
I have no idea what this is supposed to mean and I have no idea who Vox are
And you're a spaniard?
youtube.com / watch?v=5h-yGC7atBs
youtube.com / watch?v=wjphjb2lOE4
-
hmm wait for Comac C919 (https://en.wikipedia.org/wiki/Comac_C919) then we'll have more dive down occurrence pressure. Financial problem is not an excuse, 737 is bigger engines from predecessor, and that thing can dive up and down fine. this is just few lines of codes, imho.
<Needless to say what follows is speculation on my part....>
Well, the basic problem is that this is *not* a few lines of code because they f*ed up big time on this project. Their basic problem with MCAS is relying on a single sensor input. Think about that--you cannot have a life-critical <anything> reliant on a single sensor. In the original design it was not life-critical (according to first docs given to FAA) because the control was limited in its effect on the aircraft. Later....later...(time passes) and deadlines approach...they realize that they need more control and up the control space for that system. It now becomes life-critical but too late in the project for the major changes necessary for the incorporation of the THREE sensors you now need. (Two sensors doesn't cut it--you need majority voting). I don't know but I suspect that three sensors are not available and the addition of another sensor would be quite a major effort. Remember, the whole project was supposed to be QUICK and a minor modification to the 737.
So now they have screwed themselves. But conveniently no-one knows this except internally withing Boeing. The executives decide to cut their losses as you have seen--by pretending that MCAS is not life-critical and not changing the design. The result is what you can see.
-
hmm wait for Comac C919 (https://en.wikipedia.org/wiki/Comac_C919) then we'll have more dive down occurrence pressure. Financial problem is not an excuse, 737 is bigger engines from predecessor, and that thing can dive up and down fine. this is just few lines of codes, imho.
<Needless to say what follows is speculation on my part....>
Well, the basic problem is that this is *not* a few lines of code because they f*ed up big time on this project. Their basic problem with MCAS is relying on a single sensor input. Think about that--you cannot have a life-critical <anything> reliant on a single sensor. In the original design it was not life-critical (according to first docs given to FAA) because the control was limited in its effect on the aircraft. Later....later...(time passes) and deadlines approach...they realize that they need more control and up the control space for that system. It now becomes life-critical but too late in the project for the major changes necessary for the incorporation of the THREE sensors you now need. (Two sensors doesn't cut it--you need majority voting). I don't know but I suspect that three sensors are not available and the addition of another sensor would be quite a major effort. Remember, the whole project was supposed to be QUICK and a minor modification to the 737.
So now they have screwed themselves. But conveniently no-one knows this except internally withing Boeing. The executives decide to cut their losses as you have seen--by pretending that MCAS is not life-critical and not changing the design. The result is what you can see.
And I doubt very much it's the sensor's fault. I'd bet it's a dangling pointer somewhere or something like that, a software bug rather than a hardware sensor fault...
Why? Because I can't believe so many sensors can fail so many times, and only in these planes. I don't think the AoA sensors in the 737 MAX can be very different from the ones in other airplanes.
-
Additional pilot training is penalized at $1M per plane, in the Boeing sales contract with Southwest Airlines.
Meaning Southwest would be paid by Boeing $1M/plane ($31M for 31 planes thus far of 280 ordered) if additional simulator training was required above the 737NG. Quite the sales gimmick and there's your incentive keep MCAS undocumented.
-
Remember, the whole project was supposed to be QUICK and a minor modification to the 737.
So now they have screwed themselves. But conveniently no-one knows this except internally withing Boeing. The executives decide to cut their losses as you have seen--by pretending that MCAS is not life-critical and not changing the design. The result is what you can see.
That's about the size of it IMHO.
-
Imagine how loud YOU would be screaming if someone knowingly took off without EVERYTHING working and then crashed?
Well isnt that what actually happened? minus the screaming at take off rather at crash.
You do realize that's exactly what you just demanded, right?
You dont make sens in your reasoning, besides i'm not demanding anything, i just debate what others speculate in.
Nor would that fact have anything to do with how loud MT would rant when a crash is involved.
Im not ranting besides at armchair pilots like your self who claims to have a definitive answer to a crash every time it hapends. I dont see you spend time barking at fake news outlets ranting repeated news reels about these crashes and crockery inside Boing and FAA. How peculiar!
-
I'm not going to bother quoting/replying to the people that have disparaged my/Mechatrommer comments. You know who you are. If you still don't understand, than just wait a bit. This technology will eventually be on passenger aircraft.
Commercial aircrafts don't have this luxury. They have to perform reliably under all conditions, including constant climbing/descending and loss of GPS reception.
They also have to perform reliably in case of flying through a storm cloud at high altitude and the pitot tube freezing.
There seems to be no downside to having a backup to the things already on the plane. An accelerometer and gyroscope can only tell relative changes to pitch and speed, and it will go farther and farther out of calibration over time. But if it is KEPT in calibration with other sensor information, it could continue giving accurate readings for some duration of time AFTER those sensors go out. The only thing is can't account for is the direction and speed of the wind. If updated with averages generated from GPS, pitch, and changes in elevation over time, it could be kept in the right ballpark, perhaps indefinitely, even, without a traditional airspeed indicator.
Air speed is the cosign of AOA times vector speed, plus or minus the effect of local wind speed. Except for the wind speed*, everything else is available to the gyro and accelerometer and a computer/microcontroller. Or GPS, pitch, and altitude over time. Any one sensor that is missing, that info could be calculated, accurately, in real time, by the remaining sensors. ASI or AOA, just as examples. And even a gyroscope and accelerometer is more prone to certain problems and failures and inaccuracies, the failure modes are at leastr different than the failure mode of , say, pitot tubes (icing).
Heck, in the future, pilots might have a video display showing a depiction of a plane at its current pitch and with the various speeds and vectors drawn out in proportionally sized and angled arrows in real time. It could show true vector angle and vector speed (the actual speed and direction of the plane, which would be the "biggest number"), air speed (or velocity in the nose-tail axis, plus or minus windspeed correction), it would even show the "down speed" perpendicular to the airspeed, in addition to the true up/down velocity of the plane (up/down current velocity, as opposed to just vertical position/altitude). The AOA would be the angle between vector velocity and airspeed velocity.
The larger and more smooth/stable planes get (even in a stall, some of these planes can feel relatively smooth and stable), the more something like this could be useful to tell the pilot what the plane is doing in low/no visibility conditions (planes fly through clouds and storms and on moonless nights over the ocean, among other things), rather than trying to make sense of a bunch of numbers and values and forming a more abstract picture when/where there is precious little time and the pilots are working under some level of panic or confusion, and they are obviously not (in some cases) coming up with the right conclusions. A stall warning is just a single word (or a stick vibration). A picture is worth a thousand words. When the autopilot cuts out with no warning during a 10 hour flight during zero visibility and high turbulence, things can go out of whack in a hurry. The pilot's mind might have been on something else when he is suddenly handed the plane.
*Wind speed is obviously very important, but some picture is better than none. With high accuracy weather radar, perhaps some decent approximation of local wind can also be included for correction.
-
All the focus is on the MCAS algorithm, and I hope the AoA sensor failures are investigated. Failing immediately or after a few minutes in the air, I wonder what's going on there.
This new Boeing screen sucks, the AoA DISAGREE annunciator is at the bottom, AoA gauge at the top, and not sure where the second or which AoA sensor is driving the gauge. What does the gauge do when there is a discrepancy? Please add more confusion.
It violates good user interface design by not keeping related information in one spot. WTF RADIO and Barometric Pressure is next to it :palm:
-
Another report
“EVERTHING about the design and manufacture of the MAX was done to preserve the myth that ‘it’s just a 737.’
Re-certifying it as a new aircraft would have taken years and millions of dollars.
https://drive.google.com/file/d/1249KS8xtIDKb5SxgpeFI6AD-PSC6nFA5/view
-
and millions of dollars.
Yup. actually, billions were at stake. Each plane they sell is hundreds of millions, and I'm sure the margins are huge. As well the research costs and liability are huge on the other side. Either you make a bank or you lose a bank. Mere "millions" is just the interest on their loans.
With the success of the Neo, Boeing was facing the prospect of losing massive market share. The news has insinuated that Boeing execs internally predicted Airbus would encounter massive problems and delays and significant compromises when converting an existing airframe to more efficient engines.
So after Airbus pulled it off and threatened to take over American Airlines' business, Boeing decided to take on an even bigger challenge, converting an even less appropriate airframe to larger engines in even less time. I think it too early to say if this is inherently a mistake, as far as the engineering goes. Maybe the plane is 100% fine in the end and had just one unfortunate oversight. But in terms of business and safety, they might have made a costly mistake in the way the did or didn't disclose MCAS to their customers.
Boeing makes decisions for its shareholders. There is an obvious conflict of interest when safety is concerned. That's presumably one of the reasons for government oversight, e.g. the FAA and the like. I don't think anyone trusts the FAA, right now. No matter how "under staffed or underbudgeted" they can claim to be, it costs them nothing to not sign an approval/certification. It shouldn't be their job to help Boeing stay competitive. Boeing's deadlines and business future should be of no concern to the FAA. The FAA was acting more like the protector of a government monopoly than a regulartory body.
-
This new Boeing screen sucks, the AoA DISAGREE annunciator is at the bottom, AoA gauge at the top, and not sure where the second or which AoA sensor is driving the gauge. What does the gauge do when there is a discrepancy? Please add more confusion.
What do you expect for $80k per plane option! Perfection? :palm: :(
-
^I'm still curious what happens when one sensor goes out.
On a given plane, for instance, there might be 3-5 pitot tubes. And one a certain number of them go out, the autopilot will shut off. But what numbers does the pilot get to see? If 2 out of 5 go out, does he have any way of seeing the individual readings? Or does he just get the average? Or does his display just show "error."
If we go by what the news has stated and take that as a final word: in this case, it appears there would be two displays for either AOA sensor. And one sensor drives the stick shaker (stall alert) only for the one of two control columns, the one that is on that side of the plane. And from what the news has stated, the MCAS works off only one of these sensors... either the left one or the right one, presumably. So if one were to go down, it would be 50 chance that MCAS is still working correctly and 50% chance it would be fed by the affected sensor. So the procedure wouldn't change. One might presume, things would still be rolled into "runaway stab trim" protocol.
This is why after the news reports claiming that Boeing made a critical safety warning indicator an optional costly upgrade, I still don't see the connection.* That seemingly would have only a small chance to have changed the outcome. The "memory items" are still the same. There's just a footnote at the bottom that says that the AOA disagree alert might be lit. The pilots actions would remain unchanged, per this protocol.
It might prompt earlier maintenance if the AOA disagree alert had lit on prior flights (but the fault was not such that stall warning or MCAS had fired).
*Consider American Airlines response to this sensor disagree. They're the only US airline that did not pay for the optional upgrade. American rep stated "We did not install this option, because our pilots use different information [not AOA] to fly the plane." Even decades after AOA sensors are commonplace on aircraft, actual display of this info to the pilot is relatively recent (in non military aircraft). Some planes have AOA sensors, but they are only there to activate a stall alert or stick shaker.
-
This new Boeing screen sucks, the AoA DISAGREE annunciator is at the bottom, AoA gauge at the top, and not sure where the second or which AoA sensor is driving the gauge. What does the gauge do when there is a discrepancy? Please add more confusion.
What do you expect for $80k per plane option! Perfection? :palm: :(
They're working on this for months! It's like Boeing's engineering has gotten farmed out to some third world country doing discount S/W development....
Relying on a single sensor, that programmer way out of his league. Rumour has it they fired all the senior engineers with the move to Chicago, years ago.
Avionics ergonomic standards exist, for all instrumentation. The font, spacing, colours, rules for data presentation etc. is standardized. This fix shows an idiot still at large.
I see a tiny red bar on the AoA gauge but showing one pointer with two sensors is confusing. It must get ugly when there is a discrepancy.
-
This fix shows an idiot still at large.
Unfortunately, this isn't a fix. This was an available option from before the "MCAS problem" was discovered.
The "actual problems" have been "tentatively" fixed.
1. MCAS is purportedly going to utilizing data from both sensors. Whether this is go/no-go based on agreement/discrepancy or whether it works on an average would be nice to know. Per the Seattle Times, this is actually an FAA requirement for any system that can lead to injury or death, that is has to rely on more than a single sensor. So this might have been improperly certified from the get go. Even in their initial submission, Boeing stated that MCAS had the potential to lead to injury and death if it erroneously fired during a bank/turn. They did not foresee the possibility, apparently, of a total loss of the plane... that carries, apparently, a different category of risk.
2. MCAS will be limited to 2.5 degrees of trim, maximum/cumulative, regardless of actual AOA or in the case of sensor error.
As far as what Boeing has acknowledged (through reps to the media) to this point, the only devastating error was the lack of foresight regarding "human reaction." As far as we know, Boeing still considers the original implementation to be sufficient given enough training. But they'd only be speaking through expensive lawyers and sticking to a careful script.
Avionics ergonomic standards exist, for all instrumentation. The font, spacing, colours, rules for data presentation etc. is standardized.
And you'd think that having instrument readouts all performed by a computer display would make it easier to customize it. Why you need to jam a LED somewhere, when you can put a warning indication right on the screen, right by the output? I mean, I know the answer is probably something to do with code audits and lots more time and/or money.
-
Im not ranting besides at armchair pilots like your self
I've been an actual pilot since age 14, but not as a job. Also, I was once involved in MD-11 cockpit training of airline pilots. I suspect I have a better handle on reality here than actual armchair pilots.
-
This might have been posted before, but I found a huge amount of information here:
https://www.satcom.guru/2019/03/aoa-vane-must-have-failed-boeing-fix.html (https://www.satcom.guru/2019/03/aoa-vane-must-have-failed-boeing-fix.html)
Very detailed description of AoA sensors:
https://www.satcom.guru/2018/12/angle-of-attack-failure-modes.html (https://www.satcom.guru/2018/12/angle-of-attack-failure-modes.html)
-
I'll still take the opinions of all the media - who are driven by the dollar - and armchair experts - who are driven by the Media - with a grain of salt the size of Uluru.
Mentour Pilot is worth watching. He does not get into conjecture at all...
https://www.youtube.com/watch?v=CD0JabYjF3A (https://www.youtube.com/watch?v=CD0JabYjF3A)
-
This new Boeing screen sucks, the AoA DISAGREE annunciator is at the bottom, AoA gauge at the top, and not sure where the second or which AoA sensor is driving the gauge. What does the gauge do when there is a discrepancy? Please add more confusion.
The AOA indicator is displaying the information received from its own associated sensor. "AOA disagree" means the left and right AOA indicators are not displaying the same information.
:)
-
Re Gyro's question:
Actually, now that I think of it, the news gives the impression that not all of the planes even have an AOA display. I think the airline is paying $80,000 for the light in lieu of the bigger pricetag of having the AOA actually on the display cluster. Southwest is said to be upgrading all their MAX planes from having just the disagree alert to having the AOA displayed on their consoles.
AOA and MCAS on all MAX planes.
$80,000 LED alert upgrade, now standard.
AOA actually displayed on a screen, optional upgrade.
This might make the location of the light vs the display less er.. strange. The plane is maybe not even designed/planned to ever have both features installed at the same time?
Making the LED standard might be a seen as a concession that the standard emergency procedure to cover runaway stabilizer is not sufficient under all circumstances. The alert would potentially give pilots an advance notice. I wonder if they will also change the procedure/algorithm in case of a disagree alert being noticed but no other symptoms have occurred.
-
the news gives the impression that not all of the planes even have an AOA display. I think the airline is paying $80,000 for the light in lieu of the bigger pricetag of having the AOA actually on the display cluster.
imho, i dont think AOA display is compulsary. if say wind in somewhat downward direction, plane will have more room AOA (i mean angle relative to horizon) before stall, and then there's gravity's pull, so pilot will not be able to tell much by looking at AOA alone, except if assuming wind is in horizontal direction, or if he has trigonometric memory. but then i'm not a pilot (except with joystick to a $30 drone) i maybe wrong. i think real pilot dont need eye to detect a stall, they can feel it in the butt, but then i'm not sure how it goes on a big fat plane. having said that, its good to have AOA as secondary display, or as additional info.
-
^If you read details of AF447, is seems like a pilot of a large airplane doesn't feel anything useful, especially in a storm with turbulence.
"Angle relative to horizon" is apparently called the "pitch," though, FWIW. AOA is pretty much the angle of the plane/wings relative to the plane's vector (true direction it is travelling), unless you have a wing engineer nit picking you with wing chords and turbulence and other stuff. So AOA and pitch should be roughly the same when the plane is travelling in a completely horizontal direction when displayed in absolute degrees. But some planes don't display AOA as a quantity. Some planes display a corrected value between 0 and 1, with 1 being the stall limit under specific conditions (low speed, low altitude). Apparently the stall limit for AOA changes at higher cruising speeds. (I think it goes down as the plane goes faster, but I might have reversed that in my head.) It also decreases with altititude due to the air getting thinner. And, of course, different planes have different AOA limits before stall, which is one of the main reasons for the corrected value being common.
(deleted) post locked (unless requested with a good reason) i love it when reading people posts clever without knowing who they talked to (it happened to me as well sometime) there's nothing wrong to tell who you are so other reader can give more merit to posts from real people, and lesser to hearsay or imaginative (unrealistic) one, forums are becoming more like this. so reader will not be falsely informed and can make wiser decision, be more clever. not specifically to this thread discussion, it can be anywhere. fwiw.
Information doesn't always flow downhill. (Something else usually does, though). If you want to believe in authority and pedigrees, just wait for the experts at Boeing to tell you how safe their plane is. They have the manpower and resources to best certify their plane; just ask the FAA.
-
This new Boeing screen sucks, the AoA DISAGREE annunciator is at the bottom, AoA gauge at the top, and not sure where the second or which AoA sensor is driving the gauge. What does the gauge do when there is a discrepancy? Please add more confusion.
The AOA indicator is displaying the information received from its own associated sensor. "AOA disagree" means the left and right AOA indicators are not displaying the same information.
:)
When a discrepancy occurs, which AoA sensor is displayed? I see one pointer and a pilot might know whichof two possibly has good data.
There is no green or red zone on the gauge, as other displays have? Or I have to squint to see them.
-
This new Boeing screen sucks, the AoA DISAGREE annunciator is at the bottom, AoA gauge at the top, and not sure where the second or which AoA sensor is driving the gauge. What does the gauge do when there is a discrepancy? Please add more confusion.
The AOA indicator is displaying the information received from its own associated sensor. "AOA disagree" means the left and right AOA indicators are not displaying the same information.
:)
When a discrepancy occurs, which AoA sensor is displayed? I see one pointer and a pilot might know whichof two possibly has good data.
There is no green or red zone on the gauge, as other displays have? Or I have to squint to see them.
Hello floobydust,
The Captain side AOA indicator is connected to the left side AOA vane, and the First Officier side AOA indicator is connected to the right side AOA vane. This still the case if there is a "AOA disagree".
The image from your message https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2308272/#msg2308272 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2308272/#msg2308272) is showing the green and red zones, but they are not highly visible.
:)
-
So AOA and pitch should be roughly the same when the plane is travelling in a completely horizontal direction when displayed in absolute degrees.
I believe this is not correct. Pitch and AoA are only distantly related. The movement of the airfoil through the air creates an apparent movement of such air and so the AOA varies with speed through air. Also the wing does not have to be parallel to the fuselage.
It is the same in sailing (with which I am more familiar with). Imagine the boat starting out motionless in the water with the wind right across at 90º with a true wind speed of 10. Then the boat starts gaining speed and the apparent wind starts changing (apparent) direction towards the bow. Now the boat is moving at a speed of 10 with a true wind 0f 10 at 90º but the apparent wind is 14 at 45º.
-
I believe this is not correct. Pitch and AoA are only distantly related.
They are not directly related, in general; and I didn't say they were. But they are directly related in a specific condition. If 1. pitch is the angle of the plane in relation to the horizon, with pitch == 0 when the plane is horizontal and 2. AOA is the difference between the axis of the plane and the angle of its current vector, then pitch will equal AOA at the point where the plane's vector of travel matches the horizon, e.g the plane is flying exactly level without gaining or losing altitude and the plane is not banking. When the plane's vector is perfectly horizontal, and the plane is not banking, pitch and AOA are directly related if not exactly the same thing.
Even if you take an up/down wind into account, this is still true. If there's a downward wind, the plane will need to fly at a higher pitch angle in order to maintain level flight. Nose up. The vector of the plane is still level, the nose is higher, thus the AOA is also increased. They are affected in exactly the same way, as long as the plane is flying exactly horizontal/level. You can do the same thought exercise with a head or tail wind. With increasing tail wind, if you keep the true velocity of the plane constant, it's like slowing the plane. And you will need a higher AOA/pitch to keep the plane flying perfectly level. Vice versa with a head wind.
Obviously, while descending/landing the plane's AOA will be greater than the pitch. And while climbing, the pitch will be greater than the AOA. This is because the angle of the plane's vector is no longer matching the horizon. The one reading is relative to horizon, the other is relative to current vector.
The movement of the airfoil through the air creates an apparent movement of such air and so the AOA varies with speed through air.
I'm sorry, this sentence has no meaning to me.
the AOA varies with speed through air.
This part has a meaning to me, and I believe it is wrong. The AOA where a plane will stall changes with speed and altitude, but the actual AOA does not. It is still the angle between the plane's nose-tail axis and the plane's vector and nothing here changes with speed. The AOA that a plane will utilize in order to maintain level flight will change with speed (because the wings will generate more lift, they won't need as high an AOA or pitch). Provided the pilot wants to keep the vector exactly level, the AOA utilized will decrease as the plane increases in speed. But it will decrease in the exact same way that the pitch does, because as long as the vector of the plane is exactly horizontal, the AOA and pitch will be exactly the same (plus or minus any offset depending on how you are defining the reference point or zero point for either one, which is basically just an arbitrary decision, one of which an engineer handles a hundred a day; this can also be looked at as a calibration difference).
Also the wing does not have to be parallel to the fuselage.
This is irrelevant to an engineer. Whether you define the AOA as the difference in angle between the plane's vector and its fuselage... or between the plane's vector and its wing angle, it really doesn't matter. You could define the AOA for a given plane to be the angle between its vector and some arbitrary line painted on the side of the plane, even, and it wouldn't matter. Each individual plane has it's own AOA limits, anyway, which is why in many planes the actual angle isn't even displayed, and AOA is just given as a corrected number between 0 and 1. And in any case, if expressed as the actual angle, you could use a fixed offset to convert one to the other, fuselage vs wing (in case they differ by a few degrees).
It is the same in sailing (with which I am more familiar with). Imagine the boat starting out motionless in the water with the wind right across at 90º with a true wind speed of 10. Then the boat starts gaining speed and the apparent wind starts changing (apparent) direction towards the bow. Now the boat is moving at a speed of 10 with a true wind 0f 10 at 90º but the apparent wind is 14 at 45º.
See previous reply about wind angle. On second thought, you're right. The AOA as measured by a 737 sensor will increase some in a downwards winds or draft compared to pitch, even when the vector is level. This might be significant if flying through a hurricane or other localized, sudden weather phenomenon with significant vertical wind speed.
The AOA isn't some magic bean thing measured at the wing. In the case of a 737 it's just a vane on the sides of the nose. The fact it measures an angle relative to the vector (vs horizon) is significant, so that the stall warning is relatively accurate (adjusted for speed) no matter if the plane is flying level or if it is ascending or descending, because you can stall a plane in any of these cases. If you are increasing the AOA/pitch too fast, you can stall the plane even while the plane is below a normal cruising pitch. You could stall a plane while the pitch is negative, even, if you were pulling too hard out of a dive, for instance.
-
e.g the plane is flying exactly level without gaining or losing altitude and the plane is not banking.
Optimal/designed cruise pitch of 737 and similar planes is said to be 2..3 degrees, not exactly level zero. Zero pitch is descent mode.
-
Yes. Fascinating.
I.e., during level flight at cruising speed and altitude, the pitch will be 2-3 degrees. And the AOA will essentially be 2-3 degrees. Identical. It's so strange how you can infer that from the definitions of pitch and altitude if you're not a moron. If you don't automatically get it, everything an engineer does is just "magic" to you and there's no point in discussing it.
You don't have to understand basic physics and logic to fly a plane, thankfully.
I fully realize this post is condescending and arrogant.
-
I mean, it is always correct in the sense that when the angle of attack is not 0.0, the aircraft is not flying, relative to the wind, in the same direction it's pointing.
Right. Boeing does good job explaining AOA:
(http://www.boeing.com/commercial/aeromagazine/aero_12/images/attack_whatisaoa.jpg)
http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html
(http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html)
You posted this, yourself. Change the vector of the plane to match the horizon. Then puzzle to yourself what is the difference between AOA and pitch when the plane is thusly flying.
-
What exactly you are implying?
I'm very clearly stating a fact. You don't need to understand how a plane flies to fly it. The same way the best motorcycle racer in the world doesn't need to understand how the vehicle does what it does or why he does what he does to steer it... just that he gets the response that he wants. The guy that fires a gun doesn't need to know how it operates to be the world's best shot.
It would be disastrous if James Bond was the one making the gadgets and Q were out trying to save the world. Furthermore, sometimes Q has to figure out exactly how dumb James Bond is to make sure the gadgets perform as he might expect with his 20 seconds of training. In the case of MCAS, Q might have to explain things in a little more detail before James understands how to not crash the plane. If it's just too complicated, Q might have to come up with some simplified rules for James, as was often the case in the movies. He would tell James about some limitation and where something "bad" can happen, and James would inevitably find some occasion to have to "break the rule" and things work out, anyway.
It is insulting
I run out of patience. I am not sorry. Continue looking at the picture and you will either understand, or you can concede that other people get it and that's all that matters, or you can go ahead and assume that w/e you can't understand it's because "it's more complicated than that" and/or no one else can actually understand it without having a degree from AOA University.
-
I already posted this back in #537 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2285100/#msg2285100), but people are arguing about AOA again. It's not unambiguously defined.
Let's start by quoting wikipedia.
In aerodynamics, angle of attack specifies the angle between the chord line of the wing of a fixed-wing aircraft and the vector representing the relative motion between the aircraft and the atmosphere. Since a wing can have twist, a chord line of the whole wing may not be definable, so an alternate reference line is simply defined. Often, the chord line of the root of the wing is chosen as the reference line. Another choice is to use a horizontal line on the fuselage as the reference line (and also as the longitudinal axis).
OK, so:
1. Angle between the longitudinal axis of the aircraft and earth (irrespective of direction of travel): is called Pitch
2. Angle between the longitudinal axis of the aircraft and the velocity of the aircraft through the air: is called AOA (assuming we choose the "another choice" in the Wikipedia definition); and needn't be positive in straight and level flight (especially at high speed)
3. Angle between root chord of the wing and velocity of the aircraft through the air: is also called AOA (assuming the chord line definition is used).
In short, let's stop arguing over an ill-defined term like AOA. A wing designer probably has definition 3 in mind, while a pilot maybe probably has definition 2 in mind.
-
So AOA and pitch should be roughly the same when the plane is travelling in a completely horizontal direction when displayed in absolute degrees.
Also the wing does not have to be parallel to the fuselage.
It is the same in sailing (with which I am more familiar with).
e.g the plane is flying exactly level without gaining or losing altitude and the plane is not banking.
Optimal/designed cruise pitch of 737 and similar planes is said to be 2..3 degrees, not exactly level zero. Zero pitch is descent mode.
fascinating, everybody want to learn about aeroplane. iirc a diagram, pitch is angle of fuselage to motion vector and AoA is wing cross section (or effective horizontal line? damned terminology) to relative air motion angle the wing is attacking. and if look closely, angle of wing to fuselage is greater near fuselage compared to wing tip, and then there's new wing tip design thats going upward, thats to avoid some term of turbulent at wing tip, so i guess yeah, its possible cruising at 0 degree pitch (fuselage angle) while maintaining altitude. its also for comfort to passengers and those nice stewardesses during auto cruise. ps: too sad how many stewardesses wasted during the tragedies.
btw i recommend everybody should buy a book. i bought this book https://www.amazon.com/Mechanics-Flight-Warren-F-Phillips/dp/0470539755 (https://www.amazon.com/Mechanics-Flight-Warren-F-Phillips/dp/0470539755) just because i have a dream at self designing aircraft, the math and axises inside is nuts i think i only can understand less than 10% of whats inside. so i just drawed my airplane and build it disregarding the math nitty gritty. during first test flight, once its airborne it directly make a one nice circle acrobatics stunt up and then turn back and crash to the ground nose first and crash the 3d printed parts to bits and pieces, so now there's no 2nd project anymore until i find time. later during post mortem the conclusion is my airplane design is exactly as this 737 problem, engine thrust is below center of gravity (mass), so excessive thrust will nose up, it will be one hell of a manual control for the maneuver , later project it wont be manual joystick control anymore, it will be fly-by-wire arduino AI! with 6 axis complete attitude control sensoring to avoid pilot (me) stupidity :P
-
fascinating, everybody want to learn about aeroplane. iirc a diagram, pitch is angle of fuselage to motion vector and AoA is wing cross section (or effective horizontal line? damned terminology) to relative air motion angle the wing is attacking.
Damnation. The pitch is relative to the horizon/earth; it is not relative to the current vector of the plane. Look at the picture Odgen originally posted. See the dotted line? That's the plane's vector; IOW, that is the direction the plane is actually travelling. The angle of the plane (or wing, or the average angle of the wing) relative to this dotted line is the AOA, not the pitch. Pitch is relative to the earth/horizon.
i guess yeah, its possible cruising at 0 degree pitch (fuselage angle)
Of course it's possible some planes can do this. It's also possible for a plane (not a loaded 737, apparently) to fly level with a zero degree AOA of the wings, even. The wing creates lift by the curvature of the top surface. So it doesn't necessarily need to be angled up for a plane to fly level.
-
OK, so:
1. Angle between the longitudinal axis of the aircraft and earth (irrespective of direction of travel): is called Pitch
2. Angle between the longitudinal axis of the aircraft and the velocity of the aircraft through the air: is called AOA (assuming we choose the "another choice" in the Wikipedia definition); and needn't be positive in straight and level flight (especially at high speed)
3. Angle between root chord of the wing and velocity of the aircraft through the air: is also called AOA (assuming the chord line definition is used).
In short, let's stop arguing over an ill-defined term like AOA. A wing designer probably has definition 3 in mind, while a pilot maybe probably has definition 2 in mind.
You are correct with: A wing designer probably has definition 3 in mind, while a pilot maybe probably has definition 2 in mind.
Once in flight, the wing angle of incidence becomes irrelevant, to the pilots.
:)
-
The wing creates lift by the curvature of the top surface. So it doesn't necessarily need to be angled up for a plane to fly level.
yes Bernoulli's principle, but i saw youtube sometime ago that this is a myth. aerofoil only contributes miniscule to the lift esp on a big fat plane, the major contributer is wing angle of attack. i have some belief to this, a paper craft doesnt need aerofoil to lift, fighter jet will have shallower (thinner) wing profile to cut air more effectively at supersonic.
-
What exactly you are implying?
I'm very clearly stating a fact. You don't need to understand how a plane flies to fly it.
???
Having extensive experience as a Flight Instructor, I strongly disagree with your statement.
A pilot who lack understanding of how a plane flies; is an accident waiting to happen.
This is true in a small general aviation airplane, and this is true in a large airliner.
:)
-
^And yet this is not the case. Some pilots might get enough answers correct on a multiple choice test, but they don't understand it and never will. And yet they can fly us around more safely, in all likelihood, than most of the guys that designed the airplane.
The world is too complicated for the average person to understand beyond some small scope of their experience. This is purportedly part of the reason MCAS was not disclosed at first.
-
The wing creates lift by the curvature of the top surface. So it doesn't necessarily need to be angled up for a plane to fly level.
yes Bernoulli's principle, but i saw youtube sometime ago that this is a myth. aerofoil only contributes miniscule to the lift esp on a big fat plane, the major contributer is wing angle of attack. i have some belief to this, a paper craft doesnt need aerofoil to lift, fighter jet will have shallower (thinner) wing profile to cut air more effectively at supersonic.
Some aircraft have Symmetric airfoils. The F-104 wing profile is pretty close to a flat plate and a sharp leading edge.
:)
-
^Not surprising that it's a supersonic fighter jet. At super high speeds and with mega thrust to weight ratio, it doesn't need lift. Plus, how cool is it to be able to fly upside down with almost as much efficiency as right-side up?
If you tried to do that on a passenger jet, the plane would have to use to much AOA at subsonic cruising speeds and produce too much drag and burn too much fuel.
-
^And yet this is not the case. Some pilots might get enough answers correct on a multiple choice test, but they don't understand it and never will. And yet they can fly us around more safely, in all likelihood, than most of the guys that designed the airplane.
I never saw a multiple choice test during a flight test or checkride.
:)
-
What exactly you are implying?
I'm very clearly stating a fact. You don't need to understand how a plane flies to fly it.
???
Having extensive experience as a Flight Instructor, I strongly disagree with your statement.
A pilot who lack understanding of how a plane flies; is an accident waiting to happen.
This is true in a small general aviation airplane, and this is true in a large airliner.
:)
I'm not a pilot, but THIS gets a big thumbs up from me!
^And yet this is not the case. Some pilots might get enough answers correct on a multiple choice test, but they don't understand it and never will. And yet they can fly us around more safely, in all likelihood, than most of the guys that designed the airplane.
This is a poor statement, IMHO.
Kelly Johnson did not need to know how to fly the SR71 in order to design it - and Brian Shul did not need to know how to design the SR71 in order to fly it - but they could have a discussion about the flight characteristics.
-
The world is too complicated for the average person to understand beyond some small scope of their experience. This is purportedly part of the reason MCAS was not disclosed at first.
A pilot is not an average person.
;)
-
^And yet this is not the case. Some pilots might get enough answers correct on a multiple choice test, but they don't understand it and never will. And yet they can fly us around more safely, in all likelihood, than most of the guys that designed the airplane.
I never saw a multiple choice test during a flight test or checkride.
:)
... and I would hope nobody ever considers this.
Multiple choice is an extremely weak form of testing. In some cases, getting the correct answer can come from eliminating the wrong ones. This is stupid. I have this same concern for our "knowledge" driving test you need to take before getting your learner's permit. If you see a sign on the road, you need to know what it means because there won't be a list of 4 options hanging underneath it from which you choose.
This is even more critical when you're up in the sky.
Multiple choice testing is done simply because it is far easier to mark.
-
The world is too complicated for the average person to understand beyond some small scope of their experience. This is purportedly part of the reason MCAS was not disclosed at first.
A pilot is not an average person.
;)
If I'm ever in an aircraft where the pilot is an "average person", I'm going to tell them to move over!
-
Umm, I am certain many pilots are average people. If an average person with the proper training could not safely fly a commercial passenger jet, then I wouldn't get on one. I'm not talking landing on an aircraft carrier at night in high wind. If commercial passenger pilots require some superhuman skills and in depth knowledge to be safe, then these planes are not safe enough, yet.
When pilots need to score 95% percentile on the LSAT and have 130+ IQ, then I'll change my mind. Flight training contains some basic practical aerodynamics education, at best. And without basic understanding of newtonian physics it is just superficial information. 99% of the population doesn't understand basic newtonian physics.
If anything, I want my pilot to be abnormally reliable and responsible. Doesn't drink, do drugs, doesn't stay out all night. I don't care if he has an IQ of 90 or doesn't understand physics and aerodynamics as long as he has been trained and demonstrates proficiency in his training and flying. It is way more important to me that he shows up ready and prepared to do his job, and that he takes this responsibility seriously.
A good jockey doesn't need to be a biologist or an expert in husbandry.
Kelly Johnson did not need to know how to fly the SR71 in order to design it - and Brian Shul did not need to know how to design the SR71 in order to fly it - but they could have a discussion about the flight characteristics.
How many commercial pilots have this kind of relationship with the designer of the plane and can make their own tweaks to the plane during the development? Zero. Even if this was the case, it still doesn't change my point. The designer of the plane can't necessarily fly it for squat. The pilot doesn't necessarily have to understand how it flies for squat.
-
If anything, I want my pilot to be abnormally reliable and responsible. Doesn't drink, do drugs, doesn't stay out all night. I don't care if he has an IQ of 90 or doesn't understand physics and aerodynamics as long as he has been trained and demonstrates proficiency in his training and flying. It is way more important to me that he shows up ready and prepared to do his job, and that he takes this responsibility seriously.
How many pilots do you employ?
Or, are you implying that when you fly as a passenger, you do a background check on your pilot, and you get to choose your pilot?
:)
-
Umm, I am certain many pilots are average people. If an average person with the proper training could not safely fly a commercial passenger jet, then I wouldn't get on one. I'm not talking landing on an aircraft carrier at night in high wind. If commercial passenger pilots require some superhuman skills and in depth knowledge to be safe, then these planes are not safe enough, yet.
When pilots need to score 95% percentile on the LSAT and have 130+ IQ, then I'll change my mind. Flight training contains some basic practical aerodynamics education, at best. And without basic understanding of newtonian physics it is just superficial information. 99% of the population doesn't understand basic newtonian physics.
If anything, I want my pilot to be abnormally reliable and responsible. Doesn't drink, do drugs, doesn't stay out all night. I don't care if he has an IQ of 90 or doesn't understand physics and aerodynamics as long as he has been trained and demonstrates proficiency in his training and flying. It is way more important to me that he shows up ready and prepared to do his job, and that he takes this responsibility seriously.
Having watched my daughter progress through her PPL, IFR, Instructors rating, CPL and into then commercial aviation with mates dropping out from courses I can assure you ppls that acquire even a co-pilots position are much more than the average Joe or Jill. Only the cream rises to the top and that's now it must be in commercial aviation.
Even the first steps down this road require knowledge and understanding of the plane's mechanics, principles of flight, navigation and one that many struggle with; Meteorology.
-
well not an average person maybe, but a chick, maybe she can land an airplane (which is the hardest part i figured during simulation)... ;D but dont do this at home please only if all options are exhausted, for example a pilot or an "above than average" person is not currently available ATM (use your imagination)...
https://www.youtube.com/watch?v=lw6mjVIdbbc (https://www.youtube.com/watch?v=lw6mjVIdbbc)
-
Whoa.
Certainly landing is perhaps the single most difficult thing in flying an aircraft - but there are a lot of other things going on - and a lot of preparation for even the most straightforward of flights. Navigation alone is crucial - and while there are a lot of electronic systems to manage that, they still have to be set up correctly - and if they fail, the pilot will need to know how to work without them.
This is not to mention all the possible things that can go wrong! I could go on and on with speculation on this subject alone and not cover anywhere near the list that an instructor could.
In these cases, your pilot needs to be very aware of the physics of his aircraft, the systems it carries, the options available and a whole bucketload of other things and be able to work their way through an emergency situation with a clear level head. It's not as if you can just coast to the shoulder of the road if something goes wrong.
Your "average person" is not going to have a hope in hell.
-
Instruction on the principles of aerodynamics, among other things, is part of the requirements to receive a pilots license. Even for recreational pilots.
On the subject of things that can go wrong, read this:
https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/06_afh_ch4.pdf (https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/06_afh_ch4.pdf)
That PDF states the definition of "Angle of Attack" as defined for instructional and testing purposes. Pilots will be aware of that definition, even if the general public wants to argue about it.
-
The angle of attack (AOA) is the angle at which the chord of
the wing meets the relative wind. The chord is a straight line
from the leading edge to the trailing edge. At low angles of
attack, the airflow over the top of the wing flows smoothly
and produces lift with a relatively small amount of drag. As
And if by extension a pilot can't extrapolate more than one way to state this... that the nose-tail axis of the plane is essentially the same as orientation of the chord of the wing, and in fact if there is any deviation between the chord of the wing and the axis of the plane it is completely irrelevent...
I'm sure that doesn't disqualify them from flying a plane despite not being a sharpest tool in the shed.
You'd have to be especially dimwitted to be disqualified for reasons of not being able to pass a government mandated terminology regurgitation exam. I imagine most of the actual weeding out is for professionalism. Character, personality, work ethic, reliability, temperament, maturity. And then like any other profession, the politics. Additionally for a pilot, having a certain confidence-inspiring look don't hurt. If you check all those boxes, then oh, yeah. Let's see if you can actually fly the plane. Gawd let's hope so, because the rest looks perfect.
I don't want Albert Einstein to fly my plane. I want a professional pilot weeded out for his professionalism and ability to fly a plane.
-
Hello floobydust,
The Captain side AOA indicator is connected to the left side AOA vane, and the First Officier side AOA indicator is connected to the right side AOA vane. This still the case if there is a "AOA disagree".
The image from your message https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2308272/#msg2308272 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2308272/#msg2308272) is showing the green and red zones, but they are not highly visible.
:)
Two AoA sensors - you have a redundant system with no check for agreement, an original MCAS engineering error.
Now with Boeing's "fix", it seems there are two gauges (Captain, First Officer) and the fact that human beings have to have a discussion between them to see which sensor is out, or if both are out, what to depend upon.
It's playing the same song- redundant systems are safer but not so if one sensor failure gives doubt to the other's integrity. Now humans are involved to confirm the old adage "with two clocks, one can never know the correct time". I don't see the added gauges being useful, they add confusion as implemented.
-
You'd have to be especially dimwitted to be disqualified for reasons of not being able to pass a government mandated terminology regurgitation exam. I imagine most of the actual weeding out is for professionalism. Character, personality, work ethic, reliability, temperament, maturity. And then like any other profession, the politics. Additionally for a pilot, having a certain confidence-inspiring look don't hurt. If you check all those boxes, then oh, yeah. Let's see if you can actually fly the plane. Gawd let's hope so, because the rest looks perfect.
Yep all that ^.
But as you say one first has to be able to demonstrate appropriate flying skills too.
My daughter as a instructor spent a couple of years at FTA (Flight Training Adelaide) where she had to check fly the successful applicants for a few big airlines and while these guys and gals might have met their local examination requirements some couldn't make the grade when it came to the standards an international airline requires. So while you might have the goods to meet a CFL it comes down to real ability not some bit of paper.
I've had the pleasure over some decades to know a good few NZ international pilots and without exception they are very humble of their abilities.
-
Your "average person" is not going to have a hope in hell.
I actually tried this last year for a bit of a laugh. I went up in a Cessna with an instructor to see what it was about. Having zero experience at the controls and basic understanding of the physics and mechanics involved.
The instructor talked me through getting it off the ground and after a bit of time "getting a feel for the machine" the instructor commented I was a bit more "measured" than the usual "joy flight muppets" (ie I didn't want to try and stand it on its wing or do a loop) and asked me if I'd like to try the approach and landing. I could get the thing off the ground, I got it out and around the pattern, did a lap of rotto, managed all the relevant things he wanted me to manage and made it do everything he asked me to make it do.
Then came the landing. So calm as you like I lined up on a long final, and he talked me down. A bit of a crosswind, but nothing awkward. It got *busy*. Really busy. So much so that a couple of hundred feet off the ground I asked him to take control and do a go-around. So yeah, that was a little buzz box with about 4 controls to manage, I knew the theory of what I should be doing *and* I had an instructor in my ear *telling* me what I needed to be doing and it still got away from me. I've since done some landings in a 737 sim, but without the risk of damage and a crapload more inertia it's a bit more casual. Nobody minds a bounce in a sim.
I've also been lucky enough to do a lot of jumpseat approaches in bigger birds over the years, but frankly I *want* the people up the front to know not only how to competently fly the thing, but to know enough about it to make a reasoned attempt at working around any issues when things turn to porridge.
-
Even knowing what to do is not entirely enough. One has to get used to the individual planes as well. I started out in gliders, and had done plenty of solo flights in the high-wing two-place trainer. Then came the day I was allowed to fly the low-wing single-seat. I ended up too high on final approach to correct with a slip and spoilers and was forced to do a 360 to lose altitude. That was embarrassing enough, but then shortly after I put my wheel on the grass strip, I managed to ground-loop it when I let a wing drop too much. No damage, not even to the grass, but one has absolutely no control at that point and just has to ride it out. That was 45 years ago and one of those days I'll never forget.
-
Wow, there is A LOT of armchair pilots in this thread :horse:
-
Boeing's response- blaming the pilots, not their shit MCAS software and AoA sensors, is the problem.
Blaming the victim minimizes the criminal act.
Even if it was the crew's error, no (undocumented) system should be designed to rely on "a memory item" to stop a fatal dive.
-
Boeing's response- blaming the pilots, not their shit MCAS software and AoA sensors, is the problem.
Blaming the victim minimizes the criminal act.
Well, many people have wondered why they didn't execute the "uncontrolled stabilizer trim" checklist in both flights. It's not "blaming", it's wondering.
Even if it was the crew's error, no (undocumented) system should be designed to rely on "a memory item" to stop a fatal dive.
I think that thou dost not understand the point of an emergency checklist. They're not for routine use, they're for, you know, when things aren't working right.
-
Even if it was the crew's error, no (undocumented) system should be designed to rely on "a memory item" to stop a fatal dive.
I think that thou dost not understand the point of an emergency checklist. They're not for routine use, they're for, you know, when things aren't working right.
Nor do they understand WHY there are such things as "memory items".
-
Even if it was the crew's error, no (undocumented) system should be designed to rely on "a memory item" to stop a fatal dive.
I think that thou dost not understand the point of an emergency checklist. They're not for routine use, they're for, you know, when things aren't working right.
Nor do they understand WHY there are such things as "memory items".
Yes, these are things the pilots are supposed to know, cold. As in no thinking, no puzzling, just doing. And furthermore, I think it is very reasonably, very very reasonable, to expect that pilots are, when confronted with a strange situation, to be able to do some aerodynamic reasoning of their own AFTER having completed the memory items and checked them with the emergency checklist. This is what pilots call "airmanship." So far, it's looking like the pilots of these two aircraft did not demonstrate such airmanship, and that is tragic.
However, I definitely have sympathy for flooby's point that no system should rely on a memory item to stop a fatal dive. I think that is essentially true. The electronic systems should be designed to avoid emergencies, not casually drop pilots into emergencies and expect pilots to fly their way out of them. If they designed stuff that way, then the "defense in depth" benefit of having astute pilots is lost, since you are relying on that as your first line of defense, not your last.
That said, I still find all these people saying that MAX is fatally flawed, that the aircraft is unstable in normal flight, that the 737 should not have been revamped once more, that the idea of MCAS is inherently bad and dangerous, that MCAS is shit, etc rather absurd -- at least very much premature given what we know. Instead, I think the evidence is coming in that MCAS has a correctable design flaw. We will see how many people suspected that design flaw and signed off on it anyway. But fundamentally, it looks like bad engineering judgment was involved (what we used to call "a mistake") and that mistake will be corrected.
None of that makes it less tragic that so many people have died. And it will be doubly tragic if it turns out this is because Boeing engineers made a mistake that had previously been made by someone else. And triply so, if they did in knowingly. But none of that is established at this point.
-
Boeing's response- blaming the pilots, not their shit MCAS software and AoA sensors, is the problem.
Blaming the victim minimizes the criminal act.
Well, many people have wondered why they didn't execute the "uncontrolled stabilizer trim" checklist in both flights. It's not "blaming", it's wondering.
Even if it was the crew's error, no (undocumented) system should be designed to rely on "a memory item" to stop a fatal dive.
I think that thou dost not understand the point of an emergency checklist. They're not for routine use, they're for, you know, when things aren't working right.
Correct. A pilot is one who is required to consult a written checklist when he is doing tasks which he does several times each day, but is required to commit to memory the tasks which are not expected to be used in an entire career. Emergency items are committed to memory, because there's no time to locate and refer to a paper checklist.
Can an "average person" be trained well enough to accomplish the tasks that might be required of an average airline flight, in good weather, where the equipment works as it's supposed to, and no memorized checklists are required? Possibly, with some time and effort.
But being prepared for an average flight is not what the piloting job is about. They have to be able to handle all the unusual and bad things that can happen. For example, they have to know what instruments will be affected, and how, if all the pitot tubes are iced up at once, so that they can diagnose the condition, ignore the failed instruments, and safely fly using the remaining instruments. They have to know how to handle engine failures. They have to always know what airports are within gliding distance, and if there are none (as was the case for Sully's "Miracle on the Hudson") they have to recognize that quickly, and take the best available option rather than coming up short when trying to glide to a runway that is unreachable.
-
MCAS relying on a single sensor and being undocumented, optional AoA disagree indicator, are just a few of the many horrific errors contributing to these tragedies.
All the noise deflecting blame from Boeing and the FAA, protecting investor's and the stock- can't absolve this multi-billion dollar turd or return the 356 lost lives.
The Senate subcomittee hearing was tough to watch. The FAA acting Admin was horrible: "I am confident in the AOA veins that are produced and put on airplanes and I am confident in the MCAS system."
Are we saying the planes are safe and should be back up in the air? Just need another few minutes of pilot training on an iPad :palm:
JT043, JT610, ET302 problems with AoA sensors (https://www.satcom.guru/2019/03/aoa-vane-must-have-failed-boeing-fix.html)
A very good read and sleuth work there. In 2006 it was incorrect assembly- a loose set screw on a 747-400 AoA sensor problem.
Today, a detail this small could be the root cause but here we are blaming the pilots.
-
Today, a detail this small could be the root cause but here we are blaming the pilots.
I think you are having a hard time understanding why planes crash. There is not one reason. There is never "one" reason.
Aviation accidents are almost always the results of long chains of failures. To say the pilots could have saved the aircraft is not to "blame" them but to point out the obvious: that this was a link, among many, in the chain.
If these accidents were being investigated by the US NTSB, they would officially identify "proximate causes" and "contributing factors", but even this belies the reality that it takes a lot of things to go wrong to crash a plane. Some of those things would happen years earlier at an engineer's desktop workstation, during a test flight, in the assembly hangar, in a boardroom, during a regular maintenance check, and yes, in the cockpit.
-
What I'm on about is the focus should be on finding the cause(s), the contributing factors for the crashes.
Instead, it's gets corrupted in order to protect Boeing and the FAA. Blame the humans when the automation system intended to save them, kills them.
Ethiopian Airlines preliminary report is due this week.
Just in WSJ: "Ethiopian Airlines Pilots Initially Followed Boeing’s Required Emergency Steps to Disable 737 MAX System"
I guess that trim wheel was their fault, right. "memory item"? No it's a "gymnasium item".
-
Blame the humans when the automation system intended to save them, kills them.
@floobydust : knowing what you know, do you think you would have turned off those two switches or not?
-
I think you are having a hard time understanding why planes crash. There is not one reason. There is never "one" reason.
My initial reaction to your statement was "Hell no, I'll refute that". But I can't. Doesn't matter which Aviation disaster I'd like to cite, it is *always* a case of there being more than one factor and having to have the "stars align" in a particularly bastardly way for the plane to fall out of the sky. I keep going back to the 737 rudder reversal, but again it's a long chain.
And the reality is the same for pretty much any form of loss of life if you examine the issue closely enough. Maybe getting hit by a meteor would qualify, but then I don't know of any planes that have been knocked out of the sky like that.
That then goes back to the (actually scarily high) number of disasters that have been averted by competent jockeys up the front (BA-9 anyone?). I want my pilots to know how to fly a (not fatally like Alaska 261) broken aircraft. Although if you watched "Flight" you might suspend belief and think a skillful pilot might have saved that one also.
-
@floobydust : knowing what you know, do you think you would have turned off those two switches or not?
All over this thread everyone has been assuming that the pilots did not do this or that, some even suggesting that these pilots were basically unexperienced and clueless about planes, without really knowing what happened, especially since software is involved and software tends to have a life of its own.
Well, bombshell, pilots followed emergency procedures that were laid out by Boeing. This Boeing fkup could be even bigger than expected, and yet many will still blame the pilots :palm:
https://edition.cnn.com/2019/04/03/africa/ethiopian-airlines-emergency-procedures-intl/index.html
-
Well, bombshell, pilots followed emergency procedures that were laid out by Boeing. This Boeing fkup could be even bigger than expected, and yet many will still blame the pilots :palm:
https://edition.cnn.com/2019/04/03/africa/ethiopian-airlines-emergency-procedures-intl/index.html
"Citing unnamed sources familiar with the investigation, the WSJ reported that despite following the steps, which included turning off an automated flight-control system, pilots could not regain control of the Boeing 737 MAX 8.
CNN has not been able to confirm details of the report."
Let's wait and see 'eh?
-
I'd bet they did turn off the autopilot but NOT the trim cutout switch...
-
It can't do anything if you cut power to the jackscrew motor with the stab trim cutout switches.
(https://i.stack.imgur.com/P9e43.jpg)
See: https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2302188/#msg2302188 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2302188/#msg2302188)
-
This is interesting as when the power failed on this Russian plane the pilots used a glass of water in order to keep the right attitude. I guess they may have had more time to sort things but they were also trained in what to do if the electronic system did fail perhaps these days there is not so much training and it certainly looks like the manufacturers make no allowances for total failure of the systems. It begins to look like they might even be trying to lock the pilots out of the systems now.
https://youtu.be/JUfcL1Muz6M
-
It can't do anything if you cut power to the jackscrew motor with the stab trim cutout switches.
You sure? Post the cockpit wiring diagram and I'll check....
-
100% sure.
-
I don't think so.
-
After all Boeing can say it's not needed to modify anything, since even the passangers know how to cut-off trim power now... :scared:
-
This is interesting as when the power failed on this Russian plane the pilots used a glass of water in order to keep the right attitude. I guess they may have had more time to sort things but they were also trained in what to do if the electronic system did fail perhaps these days there is not so much training and it certainly looks like the manufacturers make no allowances for total failure of the systems. It begins to look like they might even be trying to lock the pilots out of the systems now.
https://youtu.be/JUfcL1Muz6M
This is a cool story, but some of those details seem very dubious. For example, a glass of water cannot be used as a substitute attitude indicator*** for the same reason your ear cannot be used for such: it can make no distinction between the acceleration of gravity and other sources of acceleration. Hence, you can easily "death spiral" an aircraft all the while with the water level. In any case, the video makes it clear that they dropped below the ceiling in order to see the ground; at that point they would not really need an AI anyway.
I also notice the wikipedia page for the incident mentions no glass of water.
I see how the loss of electricity caused them to lose their nav capabilities. I wonder, though, why they didn't still have use of primary instruments. Airspeed indicator, altimeter and vertical speed indicator do not need power at all. AI and DG are usually vacuum driven, but I can imagine them being electric in an airliner. But it would be a poor design choice indeed for that electric system not to be backed up by something non-electric. Turn coordinator usually is electric, so that would go.
Of course, on a modern airliner these sensors are all integrated onto screens, but if you look around you can usually find some or all of them duplicated somewhere on an old steam gauge.
*** notwithstanding the Tales of the Gold Monkey episode where the heroic captain keeps the aircraft level in hard IMC with a half drunk bottle of whiskey.
-
I don't think so.
George is right. These switches cut electric power. They do not go to a computer or other logic -- though I would not be surprised to find out that they actually control solenoid relays that handle the heavier load of the trim motors.
-
It looks like the stab trim wheel is too difficult to turn. The stabilizer and elevator forces combine to make high force on the jackscrew.
1982 737 manual says let go of the stick to crank the trim wheel, the "roller coaster technique", to remove elevator forces from the jackscrew.
Can't imagine the near zero G dive, screaming passengers and an emergency procedure leading you to hand cranks the crew can't move. Flipping the cutout switches back on is the only option.
They might be "soft" switches and not actually physically disconnect power to the BLDC motors but who knows.
source: https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/ (https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/)
-
They just had to correct trim with the yoke trim button BEFORE cutting power. The button on the yoke overrides the MCAS commands. The MCAS kicks in again (and again, that's the flaw) 5 seconds after the pilot releases the yoke's trim button, but that's plenty of time to flip the cutout switches. Many (well, a few, or some) pilots in previous 737 MAX flights have saved the day by doing just that. Why? How did they know? Because after the lion air 610 crash Boeing put out a safety technical bulletin explaining just that. We're going in circles in this thread...
-
..Many (well, a few, or some) pilots in previous 737 MAX flights have saved the day by doing just that. Why? How did they know? Because after the lion air 610 crash Boeing put out a safety technical bulletin explaining just that. We're going in circles in this thread...
Frankly, the fact the pilots had to manipulate the switches in order to save the day makes me pretty nervous (as a passenger). I do not want to fly in a plane where the pilots have to manipulate those switches in order to save my day.. :--
-
I do not want to fly in a plane where the pilots have to manipulate those switches in order to save my day.. :--
I certainly wouldn't want to fly in a plane that didn't have those switches, but I also don't want to fly in a plane where needing to flip them is a regular occurrence.
That is, I don't want to fly in a plane where the automation sometimes malfunctions and requires to intervene, but the sad basic fact is that this is all airplanes. And this is also why we still have pilots.
-
This is interesting as when the power failed on this Russian plane the pilots used a glass of water in order to keep the right attitude. I guess they may have had more time to sort things but they were also trained in what to do if the electronic system did fail perhaps these days there is not so much training and it certainly looks like the manufacturers make no allowances for total failure of the systems. It begins to look like they might even be trying to lock the pilots out of the systems now.
https://youtu.be/JUfcL1Muz6M
This is a cool story, but some of those details seem very dubious. For example, a glass of water cannot be used as a substitute attitude indicator*** for the same reason your ear cannot be used for such: it can make no distinction between the acceleration of gravity and other sources of acceleration. Hence, you can easily "death spiral" an aircraft all the while with the water level. In any case, the video makes it clear that they dropped below the ceiling in order to see the ground; at that point they would not really need an AI anyway.
I also notice the wikipedia page for the incident mentions no glass of water.
I see how the loss of electricity caused them to lose their nav capabilities. I wonder, though, why they didn't still have use of primary instruments. Airspeed indicator, altimeter and vertical speed indicator do not need power at all. AI and DG are usually vacuum driven, but I can imagine them being electric in an airliner. But it would be a poor design choice indeed for that electric system not to be backed up by something non-electric. Turn coordinator usually is electric, so that would go.
Of course, on a modern airliner these sensors are all integrated onto screens, but if you look around you can usually find some or all of them duplicated somewhere on an old steam gauge.
*** notwithstanding the Tales of the Gold Monkey episode where the heroic captain keeps the aircraft level in hard IMC with a half drunk bottle of whiskey.
The video itself shows cockpit shots. It's obvious it's NOT a glass cockpit, so most of the primary instruments would have been unaffected. Nor were the primary flight controls, which were engine-driven hydraulic. Basic navigation could be done manually, that was not a show-stopper. By far the most critical lost system was the fuel-transfer pump, which meant the engines were going to die as soon as the holding tanks emptied. Otherwise, they could have made it to a proper airport.
There may have been a glass of water and/or coffee in the cockpit, but I doubt the pilots actually relied on it as an instrument. Maybe the flight engineer had time to look at such things. Most likely its just some layman's idea of embellishing the story.
-
100% sure.
My point is that those switches are probably inputs to a logic system, who will later decide what to do based on 20 other inputs, all controlled by software
GeorgeOfTheJungle is 1000% correct (yes one thousand). These switchs cut the electrical power to the Horizontal Stabilizer trim mechanism.
-
https://leehamnews.com/2019/04/03/et302-used-the-cut-out-switches-to-stop-mcas/
Pilots apparently had an air speed indicator disagree. There were following protocol for that issue when the MCAS fired.
Pilots applied runaway stab trim protocol, as proscribed by beoing, in order to disable MCAS. They cut out stab trim, according to black box analysis.
At higher speeds, an MCAS'd stabilizer can not be moved back up by hand. The pilot could not release the yoke to relieve pressure on the stabilizer in order to re-trim the plane, because this would have crashed the plane, faster. They were at only 1000 feet, shortly after takeoff.
Pilot actually broke procedure by flipping the stab trim back on, in an attempt to move the stabilizer back up with the motor into some position that would not crash the plane. But MCAS fired again. And they could not correct it in time.
The button on the yoke overrides the MCAS commands. The MCAS kicks in again (and again, that's the flaw) 5 seconds after the pilot releases the yoke's trim button, but that's plenty of time to flip the cutout switches.
These pilots turned the stab trim back on only to move the stabilizer up. They would have been pressing the up button. But MCAS fired again, and this did something.. I'm sure they didn't wait 10 seconds, watching MCAS do the opposite of what they were desperately trying to do without some combination of pressing or repressing the trim up button to try to get it to respond to their manual input while also pulling back on the yoke with all their weight to try to keep the plane from crashing.
Many (well, a few, or some) pilots in previous 737 MAX flights have saved the day by doing just that. Why? How did they know? Because after the lion air 610 crash Boeing put out a safety technical bulletin explaining just that. We're going in circles in this thread...
According to the airline, the Ethiopian Air crew received all updated training after the Lion Air crash. Per what has been discovered from the black box, it looks like the pilots followed the recommended protocol in the way they had been trained. They cut out stab trim. The erroneous AOA/MCAS might have put the plane in an unrecoverable situation, stuck between a relatively slower crash and a quicker one. Manual trim not an option. Losing altitude; can't get the nose back up.
I said it a couple days ago, that MCAS needs to be able to be deactivated without cutting out stab trim. I would also not be surprised to learn that MCAS will override the trim up button, if it fires while the button is being pressed. Whether by bug or by intention. It is, afterall, an automatic action that is supposed to prevent the pilot from doing something he is not even supposed to be aware of, that the MAX handles differently than the other 737's in a way that makes it more prone to nosing up and stalling when in high AOA. If you are supposed to be able to fly the plane the same, then a 737 pilot might be intentionally dialing in manual trim up when he accidentally stalls a MAX, in which case MCAS would be useless to prevent this scenario if it doesn't override the pilot's manual trim up button press.
If there was a way for the pilots to have saved the plane by "being smarter," then whatever it is they were supposed to have done should probably be in the emergency procedure as a memory item and practiced in this kind of scenario. And if it's not 100% reliable without a simple procedure... no complex algorithm of if/and/then branches or "waiting to see what happens after you do w/e".... then it is probably too complicated to deal with this kind of scenario. The scenario appears to be pilots being dumped into a situation where they had maybe 40 seconds to figure out a way to get the the nose up... while at least one of them is fully preoccupied with heaving up on the yoke.
-
Reading that, it would seem as if the trim (nose up) button on the yoke doesn't override the MCAS (nose down) commands. But reading Boeing's TB19 it would seem it does. That would be an additional undisclosed surprise/problem to confuse the pilots.
But still they could have grabbed and stopped the trim wheel by hand to avoid more nose down trim: there's a reason those wheels are there next to them and have a clutch.
The trim wheels have retractable handles (for a reason too!), if it's true that not even both pilots in unison using the handles can apply enough force to trim back to nose up, then that plane has even more serious problems yet.
-
if it's true that not even both pilots in unison using the handles can apply enough force to trim back to nose up, then that plane has even more serious problems yet.
I think it's a matter of altitude. At a higher altitude you could let go the yoke/elevators and allow the plane to nose down for a bit while trimming, to take some of the air pressure off the stabilizer. An AOA/MCAS malfunction at low altitude can perhaps put the plane in a spot where you're stuck between a rock and a hard place.
But still they could have grabbed and stopped the trim wheel by hand to avoid more nose down trim: there's a reason those wheels are there next to them and have a clutch.
The first time this happened, the pilots were already in an unusual situation, right after takeoff and having an airspeed indicator malfunction. They were applying protocol for that issue. They perhaps didn't notice the MCAS misfire for the first several seconds. Now they are stuck with a low nose at 1000 feet and dropping; say they had 40 seconds to get the nose back up. They cut the stab trim. They try to re-trim the plane, manually. No go. They are still nose down and have 20 seconds left to figure something out. "Turning stab trim back on is against protocol, but do you have a better idea?" They turn the stab trim back on and press up... but it goes the wrong way. Say they successfully grab the wheel to stop it from turning down further. They're still up shit creek without a paddle. 10, 9, 8...
I think the aerodynamic issue might be worse than many of us imagine for Boeing to increase the MCAS response from 0.6 degrees to 2.5 degrees just to avoid stalls. I wonder if the MAX is recoverable at all, in the case if it ever did stall (at say high altitude).
-
https://leehamnews.com/2019/04/03/et302-used-the-cut-out-switches-to-stop-mcas/
If only people were intelligent and respectful enough to actually pay attention to the most important statement in that article, rather than spouting their own less-expert speculation:
We refrain from speculating more on the limited information we have available. What exactly happened in ET302 will be revealed by the preliminary report, which should be issued within days.
The trim wheels have retractable handles (for a reason too!), if it's true that not even both pilots in unison using the handles can apply enough force to trim back to nose up, then that plane has even more serious problems yet.
If that's actually true, that would be a fault with ALL 737's, not just the MAX. Remember the runaway trim procedure was written long before the MAX existed. There's many thousands of them out there, so I doubt we'll see a precautionary grounding. Southwest would be out of business, and other US airlines would be seriously crippled.
-
https://www.bbc.co.uk/news/business-47812225 (https://www.bbc.co.uk/news/business-47812225)
Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'
...
Pilots "repeatedly" followed procedures recommended by Boeing before the crash, according to the first official report into the disaster.
...
"The crew performed all the procedures repeatedly [that were] provided by the manufacturer but were not able to control the aircraft," Ms Dagmawit said in a news conference in Addis Ababa.
-
https://www.bbc.co.uk/news/business-47812225 (https://www.bbc.co.uk/news/business-47812225)
Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'
...
Pilots "repeatedly" followed procedures recommended by Boeing before the crash, according to the first official report into the disaster.
...
"The crew performed all the procedures repeatedly [that were] provided by the manufacturer but were not able to control the aircraft," Ms Dagmawit said in a news conference in Addis Ababa.
The ET investigators definitely are saying this, and they have the data and we don't. However, it doesn't quite make sense. Why would anyone repeatedly put the stab trim cutout switches into cutout if someone was not switching them back on?
Story is more complex than that statement and, per usual, press is not asking informed questions.
-
Read the 33 pages of the actual report, rather than trying to drag facts out of the news summary:
http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+%2C%28ET-AVJ%29.pdf (http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+%2C%28ET-AVJ%29.pdf/4c65422d-5e4f-4689-9c58-d7af1ee17f3e)
-
Im not ranting besides at armchair pilots like your self
I've been an actual pilot since age 14, but not as a job. Also, I was once involved in MD-11 cockpit training of airline pilots. I suspect I have a better handle on reality here than actual armchair pilots.
Thats worse then i thought, you "almost" a real pilot arguing like armchair pilot, i prefer what real 737 pilots reports in the NASA pilot database! I also notice how you move goal posts and avoid debate the real issues brought up.
So called preliminary crash reports has been done in the past and been found utterly faulty and politicized, fat lady sings when final report is done and then barely.
-
... However, it doesn't quite make sense. Why would anyone repeatedly put the stab trim cutout switches into cutout if someone was not switching them back on?
The switches might have gotten flipped back and forth, if the crew thought the cutout was not working or they couldn't move the trim wheel. There's not much else you can try when the emergency procedure is not working and you are plummeting to your death.
I wonder what the MCAS software does when things are not responding due to the cutout.
I did see a feedback block where MCAS looks at stabilizer position. If stabilizer position information goes unavailable or the motors are off-line, there's another S/W path to investigate. Integrator windup would be another.
It looks like flipping the switches back on just repeats the entire routine, starts a delay timer and then it moves another 2.5 degrees. Perhaps during the MCAS timer running, pilots have some ability to move the stabilizer and that would be a reason to keep flipping switches off and on. Nothing else is moving them out of a dive.
-
Im not ranting besides at armchair pilots like your self
I've been an actual pilot since age 14, but not as a job. Also, I was once involved in MD-11 cockpit training of airline pilots. I suspect I have a better handle on reality here than actual armchair pilots.
Thats worse then i thought, you "almost" a real pilot arguing like armchair pilot, i prefer what real 737 pilots reports in the NASA pilot database! I also notice how you move goal posts and avoid debate the real issues brought up.
So called preliminary crash reports has been done in the past and been found utterly faulty and politicized, fat lady sings when final report is done and then barely.
The word preliminary is in there for a reason. However, it's still better information than 99% of the content of this thread concerning that flight. Have you read it yet?
And you are correct in part: I don't want to debate all the made-up theories based on conjecture and fantasy. I'd rather have facts and expert opinions.
-
The ET investigators definitely are saying this, and they have the data and we don't. However, it doesn't quite make sense. Why would anyone repeatedly put the stab trim cutout switches into cutout if someone was not switching them back on?
Agree that it's hard to fathom the crew toggling those switches in and out of cutout repeatedly.
I didn't see where anyone claimed they ever put the stab trim cutout switches into cutout. The only claim I heard was that they followed the procedures.
I don't know the details of the published procedures then in effect. Under exactly what circumstances do they require putting those switches into cutout position, and what other things are supposed to be tried first? How much were the official procedures modified after the Lion Air crash?
-
The final report will take 6-12 months, and Boeing is in crisis to get the planes up as quickly as possible. They will soon run out of storage space for the produced new planes, unless production is cut back which will put a further dent in the GDP of the United States. It's that big of a corporation.
This thread is full of armchair pilots, myself included.
If people want expert opinions on 737-max aviation, and exact facts pertaining to these crashes, why expect them here on an EE forum?
-
I didn't see where anyone claimed they ever put the stab trim cutout switches into cutout. The only claim I heard was that they followed the procedures.
From the Report link that Nusa posted (Initial findings section, last bullet point):
The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working.
-
The ET investigators definitely are saying this, and they have the data and we don't. However, it doesn't quite make sense. Why would anyone repeatedly put the stab trim cutout switches into cutout if someone was not switching them back on?
Agree that it's hard to fathom the crew toggling those switches in and out of cutout repeatedly.
I didn't see where anyone claimed they ever put the stab trim cutout switches into cutout. The only claim I heard was that they followed the procedures.
I don't know the details of the published procedures then in effect. Under exactly what circumstances do they require putting those switches into cutout position, and what other things are supposed to be tried first? How much were the official procedures modified after the Lion Air crash?
Well, I think there is a good question regarding what procedures the Ethiopian investigators are referring to. The stab trim runaway procedure has been posted here before and is also in the report on page 30. Pages 32 and 33 include supplemental information provided by Boeing to ET for these jets that amplify the basic procedure. This was provided in wake of the LionAir accident.
The FDR summary in Appendix 1, page 26 does not show the position of the cutout switches, sadly. I wonder if it is in the complete FDR data or because they are switches that directly cut out the motors, they might not be recorded.
However the report says this:
"
The crew performed runaway stabilizer checklist and put the stab trim cutout switch to
cutout position and confirmed that the manual trim operation was not working.
" (p25)
It's not entirely clear what they are saying. If they are saying that attempts to trim the aircraft with the trim wheel did not work after the trim motors were put in cutout, then Boeing has a much bigger problem on its hands than MCAS.
If they are saying that manual trim switches on the yoke didn't work after the trim motors were put into cutout, then, yeah, duh. The question then becomes whether the pilots tried to trim the aircraft with the wheel, and if they did, then was there just not enough time to make the adjustment, etc.
As a pilot myself, I would not be particularly scared of an automated system that moves the trim, as long as I could disable it. On the other hand, there's no way in hell I'd launch in an aircraft where I felt that manual trim might not work.
-
I'm curious how far Airbus has gone towards full fly-by-wire. Are there any planes without manual access to trim?
In a big enough plane, it would presumably become ever more difficult to move the trim by hand. Bigger plane means bigger forces on the stabilzer. Either you have to gear it down and make a zillion turns per degree or you can't physically do it. At least not while there's significant air pressure on the stabilizer.
And you are correct in part: I don't want to debate all the made-up theories based on conjecture and fantasy. I'd rather have facts and expert opinions.
"made-up theories" Then why are you reading this thread or posting, at all?
Even if it turns out the pilots made a very obvious and egregious error that is very unlikely to ever occur again in the history of man... If there's any possible combination of events where MCAS might cause a problem despite the pilots acting appropriately, it should still be interesting to know about it. I, for one, am merely speculating scenarios that assume the pilots acted correctly. Whether or not that turns out to be the case (or if we will ever know), I would still do it.
It should also be interesting to know how dangerous it is to fly a MAX with neither power trim nor MCAS. How often does MCAS ever activate in normal flight? Never? How many times has it ever activated (not-erroneously) since the plane has been introduced. Ever? Does Boeing have some prediction or actual statistics?
-
Boeing admits its software to blame for 737 MAX crashes, says ‘sorry for lives lost’
https://www.rt.com/news/455587-boeing-sorry-lives-lost-crashes/ (https://www.rt.com/news/455587-boeing-sorry-lives-lost-crashes/)
-
Boeing IT director: "Hey we can get all these H1-B's and offshore software devs that have dodgy qualifications and can pass cert's with a TestKing multichoice exam, it will save us a few million dollars. So worth it!"
Boeing Accountant: "A few million you say? That's a lot. Divided by a few billions, it's like a whole 10 cents! Bring in the superior offshore software developers that don't know the business model and never ever say 'no' and 'you cant do this, let me explain...' I fucking hate those guys that tell me to turn the PC off and on again. I want yes-men in my department"
Boeing Legal: "Guys, we now have a 10 trillion dollar lawsuit and hundreds of lives lost because you got the mass offshore devs and a few H1-B's in to save 10 cents"
-
I still don't see where Boeing has admitted a software failure/error. As far as we know, it was working as was originally intended. The software engineers didn't come up with the parameters. *
The apology video was pretty good but it did not own up to anything specific.
*I just made myself laugh. If my clients were Boeing and I was their software guy, Boeing would come to me and say "My plane is acting funny. When you put the nose up, it like goes up and stalls. Here's the blueprint. Can you fix it with software? I can make a video if that helps. Great, you da best. Not my problem, anymore. I'll be sure to sell the plane immediately, with no testing by airplane experts or people who have otherwise ever flown an airplane, because I trust you so much and this is now a software issue, not an airplane issue."
-
I'm curious how far Airbus has gone towards full fly-by-wire.
If fly-by-wire is the subject that scares you most, don't get on Airbus. Even the primary flight controls are fly-by-wire. Lots of software.
-
^I'm more curious that if you can't even trim, manually, on some planes.... then the manual trimming of a 737 locking up under specific conditions might not be considered an issue in the least, if it weren't for the MCAS thing.
-
100% sure.
My point is that those switches are probably inputs to a logic system, who will later decide what to do based on 20 other inputs, all controlled by software
GeorgeOfTheJungle is 1000% correct (yes one thousand). These switchs cut the electrical power to the Horizontal Stabilizer trim mechanism.
Still 10000000% correct?
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696507;image)
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696513;image)
Yes. The pictures you show say that the MCAS (or something) commanded nose down trim, but there was no "corresponding motion" because the switches were in cutout. That's what we've all been saying.
There seems to be the possibility that for reasons still unknown, the manual trim (not manually actuated electric trim) wheel did not work. If true, I think that's a big deal -- even bigger than MCAS fucking up. It's one thing to have an automatic system mess with the trim of your aircraft, quite another not be able to do anything about it.
-
I wonder if a strength requirement might be introduced.
Pilot must demonstrate ability to curl 10 reps of 50 lbs, 10 reps of 200 lbs of tricep extensions, peak grip strength of 100 lbs. Lat pull is tested by duration, not reps. Pilot must be able to pull back on a yoke with a minimum of 40 lbs of force for 5 minutes.
-
There seems to be the possibility that for reasons still unknown, the manual trim (not manually actuated electric trim) wheel did not work. If true, I think that's a big deal -- even bigger than MCAS fucking up. It's one thing to have an automatic system mess with the trim of your aircraft, quite another not to do anything about it.
According to the article I linked earlier, Mentour Pilot has acknowledged that the forces on the stabilizer can be so great that it might be possible that manual trim cannot be performed.
Apparently, the farther the stabilizer is positioned out of neutral, the harder the pilot fights against the stabilizer with the elevators, and the faster the plane's airspeed, the harder it gets. Even in the video MP posted showing the proper response to faulty MCAS, the copilot could not move the stabilizer wheel by himself. It didn't move, at all, until MP started cranking on it, too.
And this is apparently based on MP's experience as a teacher, using a simulator. I'm sure the simulator is pretty good, but it might not be calibrated or capable of providing the true/full amount of resistance.
The article I linked also shared the opinion of a 737 pilot who has apparently had the task of testing actual planes after elevator/stabilizer adjustments have been made, and he states that under certain conditions, he has to push the stick forward to intentionally dive harder in order to be able to manually adjust the trim back up. This might not be a reasonable option if a temporary nose dive results in a crash.
Hence, the context of my preceding post. MP pilot did not even acknowledge the copilot's failure to manually trim the plane when commanded/dictated.* I suppose he passed the simulation. When MP helps, he takes one hand off the yoke, so he might be relieving some force on the elevators at the same time. The plane in the simulation might have had more room/altitude for this action and/or less speed and less MCAS adjustment to fix. Under a worse condition, the two pilots might have to coordinate with a Lethal Weapon style "on 3," and maybe that wouldn't even be enough. The success might be limited by the physical attributes of the pilot/s.
*We all can imagine "don't wanna die, strength." I wonder if some fear of breaking the trim wheel stopped them from going all out, if it was really not possible. I can see either case being realistic, especially if the limits/realities of manually trimming are not explored in detail during training. I am reminded of the time I tried to teach someone how to ride a motorcycle. When I asked why he didn't let off the gas or use the brakes when gunning straight into a wall, his response was that he didn't want to drop the motorcycle. So he crashed it and put his head into a wall, instead. And after crashing, whadya know? The bike fell.
-
I wonder if a strength requirement might be introduced.
Pilot must demonstrate ability to curl 10 reps of 50 lbs, 10 reps of 200 lbs of tricep extensions, peak grip strength of 100 lbs. Lat pull is tested by duration, not reps. Pilot must be able to pull back on a yoke with a minimum of 40 lbs of force for 5 minutes.
What would female pilots do ?....
-
^Same as scrawny male pilots. Hit the gym.
-
i have a better idea: pedals. Leg force is much bigger.
-
I'm assuming, perhaps incorrectly, that the trim wheels are mechanically connected to the stabilizer jack screws so that one turn on the trim wheel corresponds to one turn on the jackscrew.
Mentour Pilot has acknowledged that the forces on the stabilizer can be so great that it might be possible that manual trim cannot be performed
Under abnormal, worst case, stabilizer loading conditions how much torque do you need to put onto the stabilizer jack screws ? Quite a lot I would have thought, but to make matters worse frictional losses along the entire length of the mechanical link would increase under high load conditions, so more torque would be required on the trim wheels that at the jackscrews.
Just trying to get my head around the losses in a mechanical system at maximum load. I don't think trim wheels were designed to work at these sort of loads, not only does friction increase but stiction comes into play as well.
-
I'm assuming, perhaps incorrectly, that the trim wheels are mechanically connected to the stabilizer jack screws so that one turn on the trim wheel corresponds to one turn on the jackscrew.
Mentour Pilot has acknowledged that the forces on the stabilizer can be so great that it might be possible that manual trim cannot be performed
Under abnormal, worst case, stabilizer loading conditions how much torque do you need to put onto the stabilizer jack screws ? Quite a lot I would have thought, but to make matters worse frictional losses along the entire length of the mechanical link would increase under high load conditions, so more torque would be required on the trim wheels that at the jackscrews.
Just trying to get my head around the losses in a mechanical system at maximum load. I don't think trim wheels were designed to work at these sort of loads, not only does friction increase but stiction comes into play as well.
the trim has a build in clutch so you can override it just by grabbing a trim wheel so the forces required can't be that high
or the clutch would slip under automatic trim as well
https://youtu.be/cQirIH_DuAs
-
https://www.youtube.com/watch?v=HBqDcUqJ5_Q (https://www.youtube.com/watch?v=HBqDcUqJ5_Q)
-
@langwadt, forgot about the grab and hold thing, thanks. So it isn't a simple 1:1 mechanical linkage. That makes sense because I couldn't see it working mechanically on an aircraft that size. So it's all servo driven and the pilots have no direct control of air surfaces, it's just haptic feedback. More control systems and more rabbit holes.
EDIT: Probably wrong about the haptic feedback, I was second guessing.
-
@langwadt, forgot about the grab and hold thing, thanks. So it isn't a simple 1:1 mechanical linkage. That makes sense because I couldn't see it working mechanically on an aircraft that size. So it's all servo driven and the pilots have no direct control of air surfaces, it's just haptic feedback. More control systems and more rabbit holes.
EDIT: Probably wrong about the haptic feedback, I was second guessing.
Pretty sure it *is* a mechanical linkage, and of course it's not 1:1. It's many to 1, which you can see in the videos when the motor is turning the jackscrew to move the stabilizer a few degrees, and the wheel is going round and round.
Still, even with the mechanical advantage, it might be difficult or maybe impossible. To me, this new information makes a lot more sense to me than MCAS-pushed-the-nose-down-and-we-crashed scenario by itself ever did. Not being able to turn the trim at all or fast enough makes more sense than pilots forgot to disable the electric trim.
-
@langwadt, forgot about the grab and hold thing, thanks. So it isn't a simple 1:1 mechanical linkage. That makes sense because I couldn't see it working mechanically on an aircraft that size. So it's all servo driven and the pilots have no direct control of air surfaces, it's just haptic feedback. More control systems and more rabbit holes.
EDIT: Probably wrong about the haptic feedback, I was second guessing.
Pretty sure it *is* a mechanical linkage, and of course it's not 1:1. It's many to 1, which you can see in the videos when the motor is turning the jackscrew to move the stabilizer a few degrees, and the wheel is going round and round.
Still, even with the mechanical advantage, it might be difficult or maybe impossible. To me, this new information makes a lot more sense to me than MCAS-pushed-the-nose-down-and-we-crashed scenario by itself ever did. Not being able to turn the trim at all or fast enough makes more sense than pilots forgot to disable the electric trim.
if the clutch is so that you can override it just by holding it, then the electric motor couldn't turn the trim either
the clutch would just slip. so afaikt if the forces were so high that you couldn't turn it by hand you had reached
a point where the force on the trim was so high the electric couldn't turn it either
-
"Boeing confirmed to The Washington Post that it had found a second software problem that the Federal Aviation Administration has ordered fixed - separate from the anti-stall system under investigation in the two crashes, and that had led to the aircraft's worldwide grounding.
That additional problem pertains to software affecting flaps and other flight stabilization hardware and is therefore classified as critical to flight safety, said two officials who spoke on condition of anonymity to discuss the ongoing probe."
"... Boeing called the additional problem "relatively minor" :palm:
The CEO's little message was lame and not a single mistake admitted by Boeing. Some spin about 'we own it' for lower risk design, and a bad sensor being the cause of it all. Wow.
-
https://www.zerohedge.com/news/2019-04-04/we-own-it-boeing-admits-its-software-was-behind-737-max-crashes-says-sorry-lives (https://www.zerohedge.com/news/2019-04-04/we-own-it-boeing-admits-its-software-was-behind-737-max-crashes-says-sorry-lives)
Extract:Several hours after Ethopian investigators found that the crash of Ethiopian Airlines Flight 302 was not the result of pilot error (hence, it was the result of Boeing error), and demanded a full review of the Boeing 737 Max flight control system, just after 3pm, Boeing CEO Dennis Muilenburg took to social media where in what passed as an attempt at a a "heartfelt" apology, the CEO of the most important, for the Dow Jones, company said that Boeing was "sorry for the lives lost" and essentially admitted that it was the company's software that was responsible for the crashes, saying that "with the release of the preliminary report of Ethiopian Airlines Flight 302accident investigation, it's apparent that in both flight the Maneuvering Characteristics Augmentation System, known as MCAS, activated in response to erroneous angle of attack information."
Here are Muilenburg's prepared remarks:
We at Boeing are sorry for the lives lost in the Boeing 737 MAX accidents. These tragedies continue to weigh heavily on our hearts and minds and we extend our sympathies to the loved ones of the passengers and crew on board Liion Air Flight 610 and Ethiopian Airlines Flight 302. All of us feel the immense gravity of these events across our company and recognize the devastation to the families and friends of the loved one who perished. The full details of what happened in these two accidents will be issued by the government authorities in the final reports.
But with the release of the preliminary report of Ethiopian Airlines Flight 302accident investigation, it's apparent that in both flight the Maneuvering Characteristics Augmentation System, known as MCAS, activated in response to erroneous angle of attack information.
The history of our industry shows most accident are caused by a chain of events. This again is the case here, and we know we can break one of those chain links in these two accidents. As pilots have told us, erroneous activation of the MCAS function can add to what is already a high workload environment. It's our responsibility to eliminate this risk. We own it, and we know how to do it.
-
N:1 trim wheel to jack screw ratio makes sense from a mechanical advantage point of view but then you have to turn the trim wheels N times faster than the motors that could be driving one or both jack screws and try to fly the aircraft at the same time.
-
Preliminary report:
http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+%2C(ET-AVJ).pdf (http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+%2C(ET-AVJ).pdf)
At 05:39:55, Autopilot disengaged,
At 05:39:57, the Captain advised again the First-Officer to request to maintain runway heading and that they are having flight control problems.
At 05:40:00 shortly after the autopilot disengaged, the FDR recorded an automatic aircraft nose down (AND) activated for 9.0 seconds and pitch trim moved from 4.60 to 2.1 units. The climb was arrested and the aircraft descended slightly.
At 05:40:03 Ground Proximity Warning System (GPWS) “DON’T SINK” alerts occurred.
At 05:40:05, the First-Officer reported to ATC that they were unable to maintain SHALA 1A and requested runway heading which was approved by ATC.
At 05:40:06, left and right flap position reached a recorded value of 0.019 degrees which remained until the end of the recording.
The column moved aft and a positive climb was re-established during the automatic AND motion.
At 05:40:12, approximately three seconds after AND stabilizer motion ends, electric trim (from pilot activated switches on the yoke) in the Aircraft nose up (ANU) direction is recorded on the DFDR and the stabilizer moved in the ANU direction to 2.4 units. The Aircraft pitch attitude remained about the same as the back pressure on the column increased.
At 05:40:20, approximately five seconds after the end of the ANU stabilizer motion, a second instance of automatic AND stabilizer trim occurred and the stabilizer moved down and reached 0.4 units.
Sorry guys, but this pilot... should have flipped the cutout switches just after restoring (*) trim between 5:40:12..5:40:20 and they would all be alive now. It's sad.
And that, unlike the captain, the "rookie" pilot were the first to diagnose the problem correctly... says a lot. To me it seems as if the captain had not read and comprehended TB19, and the FO being only the "rookie" copilot was not in charge although he might have been better prepared to face the situation.
"Ethiopian Airlines pilot of doomed flight didn’t take training on 737 MAX simulator"
https://duckduckgo.com/?q=Yared+Mulugeta+737+max+simulator (https://duckduckgo.com/?q=Yared+Mulugeta+737+max+simulator)
(*) barely, to 2.4 units instead of the more proper 4.6 they had before.
-
Sorry guys, but this pilot... should have flipped the cutout switches just after restoring (*) trim between 5:40:12..5:40:20 and they would all be alive now. It's sad.
So do if they would have not take off at all...
That point you refer was actually 3 minutes before the crash, and they did cut off trim after that.
-
Why when I say that the pilot screwed up there is someone who understands that I'm trying to exculpate Boeing?
-
It is not clear if the pressure on the stabiliser was too high and the motor clutch slipped when power was turned back on and the pilot attempted to adjust it.
-
I don't know the details of the published procedures then in effect. Under exactly what circumstances do they require putting those switches into cutout position, and what other things are supposed to be tried first? How much were the official procedures modified after the Lion Air crash?
The Mentour Pilot video about this literally performs the entire “runaway stabilizer trim” checklist in a 737 simulator and then explains each step in detail.
-
100% sure.
My point is that those switches are probably inputs to a logic system, who will later decide what to do based on 20 other inputs, all controlled by software
GeorgeOfTheJungle is 1000% correct (yes one thousand). These switchs cut the electrical power to the Horizontal Stabilizer trim mechanism.
Still 10000000% correct?
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696507;image)
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696513;image)
Of course yes still 1000000000000% correct :-+
You do not cite your source, but your text reads that there was a "trim command" without any movement of the Horizontal Stabilizer; because the electrical power to the Horizontal Stabilizer trim mechanism had been removed by the STAB TRIM Switches being in the CUT-OUT position.
:)
-
It's not entirely clear what they are saying. If they are saying that attempts to trim the aircraft with the trim wheel did not work after the trim motors were put in cutout, then Boeing has a much bigger problem on its hands than MCAS.
If they are saying that manual trim switches on the yoke didn't work after the trim motors were put into cutout, then, yeah, duh. The question then becomes whether the pilots tried to trim the aircraft with the wheel, and if they did, then was there just not enough time to make the adjustment, etc.
As a pilot myself, I would not be particularly scared of an automated system that moves the trim, as long as I could disable it. On the other hand, there's no way in hell I'd launch in an aircraft where I felt that manual trim might not work.
The mechanical trim system of the Boeing 737 have been installed in more than 10 000 Boeing 737 since the '60s.
:)
-
It's not entirely clear what they are saying. If they are saying that attempts to trim the aircraft with the trim wheel did not work after the trim motors were put in cutout, then Boeing has a much bigger problem on its hands than MCAS.
If they are saying that manual trim switches on the yoke didn't work after the trim motors were put into cutout, then, yeah, duh. The question then becomes whether the pilots tried to trim the aircraft with the wheel, and if they did, then was there just not enough time to make the adjustment, etc.
As a pilot myself, I would not be particularly scared of an automated system that moves the trim, as long as I could disable it. On the other hand, there's no way in hell I'd launch in an aircraft where I felt that manual trim might not work.
The mechanical trim system of the Boeing 737 have been installed in more than 10 000 Boeing 737 since the '60s.
:)
Indeed. It would be surprising if the discovered a new failure mode or if the max system is different enough to have a new failure mode. But it is surprising that pilots cannot handle a runaway trim situation, too, so we have to be open to surprising things.
It could also be that not a lot of people have tried to pull many 737s out of deep dive with significant nose-down trim. So despite the many overall aircraft hours, this could be a relatively unexplored flight regime.
-
[quote
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696507;image)
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696513;image)
[/quote]
Umm... I recall that the crash investigators early on reported that they found the trim jack screw in the wreckage was at end of travel. So the MCAS system had driven it right to the end, before the pilots did (or didn't?) think to turn off power to the MCAS system.
Supposedly they could then have wound it back manually with those wheels on the central console. But either they didn't think of that in time, or they tried and it didn't work. At all, because the jack screw was still at end of travel in the wreckage.
The question that occurs to me - is there a clutch between those manual winding wheels, and the actual jack screw?
Because when something drives a worm screw hard against its end stop, such mechanisms tend to lock up hard.
Maybe the jack screw was jammed, and attempts to wind it back manually failed because a clutch was slipping?
That would be a whole 'nother level of design incompetence on Boeing's part.
I can imagine no one ever thinking to try doing that during system testing. Why would it ever be jammed hard against the end?
Or maybe they thought 'better put in a clutch, so the stupid pilots don't keep winding it to the end stop, and jam it.'
Never thinking 'what if it's already jammed, and they need to un-jam it?'
Or maybe the pilots, unfamiliar with the whole MCAS system and the manual trim wheel specifically, were just trying to turn it the wrong way?
-
The mechanical trim system of the Boeing 737 have been installed in more than 10 000 Boeing 737 since the '60s.
This is precisely the problem - decades of small changes to a design leads to cover ups on the newly introduced safety violations.
Speed, payload and the stabilizer size increased, surely the jackscrew loads are higher.
Anyone do the evaluation if the antiquated manual trim system is realistic?
The wheels seem to be a dinosaur safety item, something giving "coverage" for many possible failures but do they work at all? How many times have they been used successfully in the past 60 years?
You want to be the engineer telling his boss "um, the trim wheels need to be twice the size, they are too small". This is when you're told "don't worry about it, the project is behind schedule and nobody really uses manual trim anyway, there's no room in the cockpit" so it gets swept under the rug.
-
[quote
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696507;image)
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=696513;image)
Umm... I recall that the crash investigators early on reported that they found the trim jack screw in the wreckage was at end of travel. So the MCAS system had driven it right to the end, before the pilots did (or didn't?) think to turn off power to the MCAS system.
Supposedly they could then have wound it back manually with those wheels on the central console. But either they didn't think of that in time, or they tried and it didn't work. At all, because the jack screw was still at end of travel in the wreckage.
The question that occurs to me - is there a clutch between those manual winding wheels, and the actual jack screw?
Because when something drives a worm screw hard against its end stop, such mechanisms tend to lock up hard.
Maybe the jack screw was jammed, and attempts to wind it back manually failed because a clutch was slipping?
That would be a whole 'nother level of design incompetence on Boeing's part.
I can imagine no one ever thinking to try doing that during system testing. Why would it ever be jammed hard against the end?
Or maybe they thought 'better put in a clutch, so the stupid pilots don't keep winding it to the end stop, and jam it.'
Never thinking 'what if it's already jammed, and they need to un-jam it?'
Or maybe the pilots, unfamiliar with the whole MCAS system and the manual trim wheel specifically, were just trying to turn it the wrong way?
[/quote]
afaiu the trim wheels are connected to the jack screw with cables, I image the clutch being between the electric motor
and the jackscrew, so that by grabbing the wheels the motor cannot move the jack screw
-
afaiu the trim wheels are connected to the jack screw with cables, I image the clutch being between the electric motor
and the jackscrew, so that by grabbing the wheels the motor cannot move the jack screw
Yes, there's definitely a clutch between the motor and jackscrew. Demonstrated by being able to halt auto-trim by grabbing and holding the heel.
My question is whether there is _another_ clutch between the wheel and the jackscrew. Or maybe just a potential for the cables to slip. Those have to be a continuous loop, like a belt, since the manual wheel can take many turns.
A combination of jammed jack screw, and slipping manual adjustment clutch (or cables) might have featured in these accidents,
Hmm... that cable loop has to run between the cockpit and the tail, which makes it quite long. I wonder... in a steep nose-down angle, maybe there's less droop in the cable loop and more of its own weight causing cable lengthening. Allowing it to slip? Suppose it just slips on the trim wheel pulley (or whatever) ONLY if the plane is already steeply nose down? (And the jackscrew is jammed.)
-
Yes, there's definitely a clutch between the motor and jackscrew. Demonstrated by being able to halt auto-trim by grabbing and holding the heel.
If it is possible to halt auto-trim by hand grabbing and holding a trim wheel, it means that a clutch would be between the electrical trim motor and the jackscrew, possibly within the gearbox.
There would be not clutch between the trim wheels and the jackscrew. Boeing 737 Aircraft Maintenance Manual (AMM) is not showing any clutch in this part of the system either.
:)
-
From the video (Yesterday at 01:42:52 am ) explaining preliminary report explain why manual trim did not work: With high speed at low altitude there is too much aerodynamic pressure to do a manual trim. It even looks like the electric trim has more power. Beside the trim problem the indication is that the plain was too fast - just too much power for an about leveled flight.
My (not a pilot) conclusion from the report is that the crew initially did things according to the changed instruction from Boing and turned off electric trim after the second AND event. After they where not able to do a manual trim, they turn on the electric trim (against the Boing instructions) an did a successful correction via the switches on the yoke - however not enough (maybe they where to cautious) and they forgot to turn off the electric trim after this.
Do the pilots see the raw information from the AoA sensors ? If so it should have been obvious that the left AoA sensor was bad. Even the computer should have know that the value is obviously wrong - maybe the 2nd change Boing needs to do.
The changed engine position and thus more coupling of engine power to trim caused an additional problem, not just the danger of getting too high an AoA where the MACS system was made for. In the situation the pilots possible did not reduce the engine power to reduce the speed as this would have cause an additional force towards nose down. To get a comparable feeling to the old 737 they might need assistance for the opposite direction too (e.g. trim nose up when the engine power is reduced).
A point that sounds odd to me is that there was not only the left side AoA sensor not working, but other sensors on the left side were also giving poor readings - maybe there was a common cause, effecting more than one sensor.
-
The graphics in the report shows the events with the trim cutout switches, imho..
First they cutout the trim with the switch, MCAS trimmed once but without actual movement of the trim, then was the trim cutout switch engaged again "ON" (no trim cutout), the MCAS automatic took over the jackscrew, then came to MCAS trimming nose down for 4.5 seconds [why not for 9secs??] (and the trim jackscrew remained in that position till the end), they tried hard with the column for ~6secs and it helped, then again for 6secs and it helped but less, and 3secs later the 6secs long steep dive followed.. It took 24secs from the start of last MCAS trimming till the end..
-
then came to MCAS trimming nose down for 4.5 seconds [why not for 9secs??]
Answer is in AOA-L (deg) graph. - After 4.5 secs of final trim that resulted in unrecoverable by pilots 45 degree dive, faulty left AOA indicator reached zero degrees and MCAS decided "everything about flying is good now"... :/
[edit] I think, many from Boeing and FAA shall go straight to jail. Airspeed tubes indicates overspeed, left AOA indicates maximum possible value 75 degrees which together more or less means wings are gone, yet MCAS do not care to abort or look into another AOA sensor. It decides to nose-dive while ground proximity radar is creaming, with one and only input from senor which unfortunately is faulty :palm:
-
Ok, I see the AOA_L started to "work" again during the last MCAS.
From what I see there it also means the "Manual Electric trim" works when the switches are in cutout position. They did 3x manual electric trim and it worked fine while the MCAS had no access to the jackscrew. I've seen somewhere the cutout position means the jackscrew's servo is cut off of electricity.
Btw, when looking at AOA_L and AOA_R waveforms, the left AOA got jammed in top position after the right AOA did a "larger drift up", and started to work again after the right AOA did "a larger drift down". Looks like a sw bug..
-
From what I see there it also means the "Manual Electric trim" works when the switches are in cutout position.
The TB19 says clearly that electric trim does NOT work after cutout:
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=698151;image)
-
OK, then they switched into "no cutout" position sometime before the last two manual electric trims. And few seconds afterwards the last MCAS fired (still with AOA_L jammed in top). What is the period MCAS checks whether to trim or not?
-
“In the event of erroneous AoA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds,” says Boeing. “The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released.”
https://airwaysmag.com/industry/lion-air-crash-boeing-warns-737-max-operators-of-potential-trim-fault/
-
Thus another line for their MCAS sw specification -> When the air speed is higher than 300knots and the altitude is lower than 12000feets do not allow MCAS trim..
-
Thus another line for their MCAS sw specification -> When the air speed is higher than 300knots and the altitude is lower than 12000feets do not allow MCAS trim..
I think that is an artificial constraint to limit the impact of the "problem". I'd prefer the problem gets identified, thoroughly characterised and fixed properly.
Besides, it seems to me that a properly functioning MCAS is more valuable at lower altitudes, so excluding those would be a move in the wrong direction.
-
The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches
It worked exactly as described. While "05:40:27, the Captain advised the First-Officer to trim up with him", MCAS was already trimming for around 6 seconds. It immediately stopped and manual electric trim-up followed w/o delay.
Thus another line for their MCAS sw specification -> When the air speed is higher than 300knots and the altitude is lower than 12000feets do not allow MCAS trim..
According to flight recorder data first MCAS trimdown (at 05:40:00) was ~250 kts and ASL less than 8000 feets. AGL was around 1500 or so - way too close to ground for diving. Pilots definitely got huge inflow of adrenaline.
-
The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches
It worked exactly as described. While "05:40:27, the Captain advised the First-Officer to trim up with him", MCAS was already trimming for around 6 seconds. It immediately stopped and manual electric trim-up followed w/o delay.
Should have kept trimming nose up longer, to 4.6 units, then flip the cutout switch, and from then on manually for the remainder of the flight.
-
From what I see there it also means the "Manual Electric trim" works when the switches are in cutout position. They did 3x manual electric trim and it worked fine while the MCAS had no access to the jackscrew. I've seen somewhere the cutout position means the jackscrew's servo is cut off of electricity.
Watch Mentour Pilot's video about runaway stab trim. It's very clear: the cutout switches disable ALL electric control of the stabilizer trim, including the buttons on the yoke.
Edit: If the following post is correct, and I'm understanding it correctly, then Mentour is wrong, and the cutout switches in the MAX don't disable MCAS. This would be a damning revelation, since it'd mean that the only way to kill MCAS would be to turn around and pull the fuses to the stab trim motors.
-
I feel theres a lot of assumption here, the 737 Max is a plane that might have modifications over previous 737, and unless someone has wiring schematics these are just assumptions.
The pdf in msg #874 is for the 737 MAX: https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2325078/#msg2325078 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2325078/#msg2325078) and says it quite clearly:
The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released. Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC.
Unless the .pdf is wrong...
-
I feel theres a lot of assumption here, the 737 Max is a plane that might have modifications over previous 737, and unless someone has wiring schematics these are just assumptions.
Seems like cutout switches operated properly, as described. Following events show that cutout affected both manual electric trim and MCAS as well. Manual electric trim inputs at 05:43:11 means they disengaged cutout switches on purpose - for manual electric trim because were unable to trim using mechanical wheel.
At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and FirstOfficer confirmed stab trim cut-out.
At 05:40:41, approximately five seconds after the end of the ANU stabilizer motion, a third instance of AND automatic trim command occurred without any corresponding motion of the stabilizer, which is consistent with the stabilizer trim cutout switches were in the ‘’cutout’’ position
At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try.
At 05:41:54, the First-Officer replied that it is not working
At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,4002 ft, two momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in the ANU direction from 2.1 units to 2.3 units.
At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in approximately 5 seconds.
Obvious question: why just short manual electric trim inputs if they have to pull-up so hard? They did not feel it working? - Flight recorder shows that manual trim helped, they just had to trim much longer, that would save all those lives lost. Why there is no discussion in audio recording about disengaging cutout switches before last two manual trims and last, critical MCAS trim?
-
After the accident it is always easy to say what should have been done. But it was a hot situation, I am not sure how many could keep a cold head at that. Perhaps they were not the world's best pilots, but the report highlighted that they were trying to do the right thing at least, and don't forget that the plane was handicapped... I am also sure they did not want to die.
MCAS as implemented was a disaster waiting to happen if the last crew would have landed safely, Boeing probably wouldn't give a sh!t about it and MAXes would still fly around, as they were safe.
-
Obvious question: why just short manual electric trim inputs if they have to pull-up so hard? They did not feel it working? - Flight recorder shows that manual trim helped, they just had to trim much longer, that would save all those lives lost. Why there is no discussion in audio recording about disengaging cutout switches before last two manual trims and last, critical MCAS trim?
Lots of reasons that I can speculate.
1. A stall at this altitude would result in a complete loss. Trimming up too high/fast while also pulling back on the column can be dangerous. How dangerous is the MAX with no MCAS? No one has really discussed this.
2. Familiarity. Pilots are probably not used to making huge manual trim adjustments. And on a plane this size, w/e changes you do might take awhile until you get the result. By the time you are certain of the result, you might have gone too far.
3. The first officer did the trim adjustment. The captain was flying. The first officer couldn't know how hard the captain was still pulling on the yoke unless he communicated it. And the captain didn't specify how much trim to give. He did not ask for more after the FO gave the trim. Maybe they were preoccupied and not able to communicate fast enough.
4. Training: In their training they might not have encountered such large MCAS trim adjustments. In MP's simulation, the trim wheel just moves a tiny bit every few seconds. Maybe these pilots undertook similar training. And what got ingrained was what they did under stress.
Maybe other pilots can tell us if these trim number have any meaning to 737 pilots and/or if/where they are displayed. Or do pilots generally make relative changes to the trim without regard to the actual value. Nowhere in the voice recordings do we know of that either pilot mention the absolute trim value (2.1, 2.3 4.5) or quantify trim adjustments in terms of seconds or other units. And nowhere did I read they mention "AOA" or "MCAS" failure/malfunction.
5. Time dilation. In the moment, that ~3 seconds of manual trim might have felt like 10 seconds. And it may have been difficult to read pitch and speed and trim value while the ground was so close. When too much up trim can result in the plane crashing, and you've never had to correct for such a massive trim down before, it might be hard to do. Like a surgeon does fine cuts for 30 years, but in case of some specific emergency he essentially has to whack his patient with a hatchet. FO even asks permission before attempting manual trim. So it's probably a huge part of his job training to "not actively do anything" that can crash the plane, and that any input he usually makes is typically more gradual/careful in comparison to the hatchet swing this situation calls for... and this situation developed very rapidly/suddenly without much time to really take in the entire gravity. The pilots were probably still relying on thousands of repetitions and habit of their many hours of normal flight, to some extent. As it really is to be expected, that a modern passenger plane can be routinely flown without too much critical thinking on the end of the pilot under 99.99% of circumstances, and under more fortunate conditions there would be more time for rationalization and communication/discussion before performing a more drastic/extreme human action.
Also, the voice transcript makes it sound like the captain did not try to help in the manual trim operation. Maybe he was pulling on the column so hard he couldn't let go with one hand to help, in the way that MP does in his simulation. OTOH, he does call for the FO to help with the manual electric trim button, so maybe his button wasn't working or he felt like it wasn't working. The latter suggests there might be an undisclosed-as-of-yet software/circuitry bug that is perhaps associated with AOA sensor failure.
-
Boeing farmed out the MCAS software and hardware development to Rockwell Collins.
Safety-critical software sub-contracted out is a known terrible idea. The S/W requirements have to be so well defined and documented to toss over the fence to the coders. They usually know nothing about the system they are working on, or have a proper system simulator for fully testing the code.
The end result is low quality software. Each can assume the other did the testing, which does not happen beyond functionality checks with no regard for undefined scenarios.
"...Collins issued a software update to 737 Max flight-control systems on Jan. 25, designed to change MCAS functionality to improve its safety “when flap position failures are detected".
Another basic fault missed in the original software?
There was a second Jan. 25 MCAS bug fix issued, but no word on what it covered or whose planes have that update.
The lawsuits will be interesting, joint liability will cost both Boeing and UT.
It looks like if you were involved with MCAS or the AoA sensors, you are liable as a sub-contractor or even parts suppliers are worried.
https://www.washingtonpost.com/business/economy/boeings-737-max-design-contains-fingerprints-of-hundreds-of-suppliers/2019/04/05/44f22024-57ab-11e9-8ef3-fbd41a2ce4d5_story.html (https://www.washingtonpost.com/business/economy/boeings-737-max-design-contains-fingerprints-of-hundreds-of-suppliers/2019/04/05/44f22024-57ab-11e9-8ef3-fbd41a2ce4d5_story.html)
-
Boeing farmed out the MCAS software and hardware development to Rockwell Collins.
Safety-critical software sub-contracted out is a known terrible idea. The S/W requirements have to be so well defined and documented to toss over the fence to the coders. They usually know nothing about the system they are working on, or have a proper system simulator for fully testing the code.
The end result is low quality software.
If the requirements are not crystal clear and unambiguously formulated you get GIGO.
Testing is part if the contract. As we already know by now Boeing had no clue what the input of the MCAS system in ALL possible cases/scenarios was, so the requirements were incomplete, can't blame the SW team for something they did not know.
-
^I agree.
Boeing farmed out the MCAS software and hardware development to Rockwell Collins
In addition is seems strange that a billion dollar airplane manufacturer has to subcontract such a simple software problem on their own plane and FCC. Did Boeing really fire every engineer who could do such things? Or did they subcontract the entire system (perhaps to Rockwell Collins) from the get go, decades ago?
As for the manual trim locking up, and "the same (adequate) system used on 737 for 50 years?" The MAX engines give the plane way more nose up force, putting increased forces on the stabilizer/elevators, for one thing. MCAS for another. Boeing exec states plane crashes are usually due to multiple problems, and in this case Boeing may be holding a bag containing several of these problems.
-
MCAS = Multiple Crashes Assured System
MCAS = May Crash Aircraft Sometimes
-
Somewhat related, and a real SW screw up:
https://twitter.com/ChinaAvReview/status/1114802018919411712
-
4. Training: In their training they might not have encountered such large MCAS trim adjustments. In MP's simulation, the trim wheel just moves a tiny bit every few seconds. Maybe these pilots undertook similar training. And what got ingrained was what they did under stress.
Frankly, to see a mechanical wheel in a cabin of a high tech plane in 2019 is something weird. I do understand it is a simple and proven technology, and there are many mission critical systems which still works in a mechanical manner, but messing with the wheel under +/-2G is something highly questionable. The guy in the video had problems with the wheel even happily sitting in a simulator without any stress in life or death situation. Imagine 1Gp-p in all three axis with ~-2-3secs periods for 5minutes and finally -1 to -2G in last seconds.. See the graphs in the report.
I think the jackscrew itself (not counting the MCAS) is a single point of trouble. I doubt there is an another system in modern airplane which is not backuped with something automatic.
Imagine the screw breaks (as it happened due to missing lubrication in past), or the servo get jammed in an fatal position, etc. There should be a hydraulic, or pneumatic system (pyro generator?) which sets the stabilizer into a neutral position upon single button push..
-
Well, technically, it wasn’t the screw that failed on Alaska 261, it was the nut that rode up and down the screw.
Indeed it’s a single point of failure, but then again, screws are fundamentally reliable things. Any automatic backup is likely to be less reliable than the screw and nut.
It might require careful gearing to maintain sync, but I suppose one could have two redundant jackscrews, each of which is sufficient to support the horizontal stabilizer on its own.
-
Boeing farmed out the MCAS software and hardware development to Rockwell Collins
In addition is seems strange that a billion dollar airplane manufacturer has to subcontract such a simple software problem on their own plane and FCC. Did Boeing really fire every engineer who could do such things? Or did they subcontract the entire system (perhaps to Rockwell Collins) from the get go, decades ago?
"Boeing ...changing culture from quality of product to bottom-line-only, and from engineering-focused family to an executive-and-worker style hierarchy. Boeing stopped being a company where decisions were made based on the best engineering opinion available, and started resembling more like an MBA-management style of company, or a GE Jack Welch style of management company."
Outsourcing became the new mantra. Huge problem is that outsourcing manufacturing is different than engineering.
You can't treat knowledge-workers, skilled labour as if they are parts. Outsourcing safety-critical software and hardware is different than outsourcing nuts and bolts, rivets.
I can see Boeing's engineering moving (necessarily) at a turtle's pace, but it seems to have been moving at a dinosaur's pace, compared to competitor Airbus.
Instead of cleaning up the in-house processes 'oiling the machine', getting barriers to engineering out of the way, they just farmed out development.
This is a popular management fad for many years now. I've never seen it work.
-
Boeing farmed out the MCAS software and hardware development to Rockwell Collins
In addition is seems strange that a billion dollar airplane manufacturer has to subcontract such a simple software problem on their own plane and FCC. Did Boeing really fire every engineer who could do such things? Or did they subcontract the entire system (perhaps to Rockwell Collins) from the get go, decades ago?
"Boeing ...changing culture from quality of product to bottom-line-only, and from engineering-focused family to an executive-and-worker style hierarchy. Boeing stopped being a company where decisions were made based on the best engineering opinion available, and started resembling more like an MBA-management style of company, or a GE Jack Welch style of management company."
Outsourcing became the new mantra. Huge problem is that outsourcing manufacturing is different than engineering.
You can't treat knowledge-workers, skilled labour as if they are parts. Outsourcing safety-critical software and hardware is different than outsourcing nuts and bolts, rivets.
I can see Boeing's engineering moving (necessarily) at a turtle's pace, but it seems to have been moving at a dinosaur's pace, compared to competitor Airbus.
Instead of cleaning up the in-house processes 'oiling the machine', getting barriers to engineering out of the way, they just farmed out development.
This is a popular management fad for many years now. I've never seen it work.
To be fair, it's not like Rockwell Collins doesn't have a solid reputation and history developing avionics for airliners. It actually seems to me rather reasonable that an aircraft manufacturer would buy from a company that specializes in avionics. Now, folks are right that a system like MCAS, designed to protect the airplane, is probably harder/more risky to farm out than, say, nav equipment, which has pretty much nothing to do with the airframe.
Does Airbus not farm out work to subcontractors?
-
I think the jackscrew itself (not counting the MCAS) is a single point of trouble. I doubt there is an another system in modern airplane which is not backuped with something automatic.
Imagine the screw breaks (as it happened due to missing lubrication in past), or the servo get jammed in an fatal position, etc. There should be a hydraulic, or pneumatic system (pyro generator?) which sets the stabilizer into a neutral position upon single button push..
I don't see how a hydraulic or pneumatic system would be able to move the stabilizer with the jackscrew still linked to the stabilizer. There would need to be an explosive bolt linkage or something. The problem is MCAS uses the stabilizer in a way where a malfunction can put it in an extraordinarily unusual position before the pilots might be able to react, whether that's due to insidious onset or due to protocol that is too slow for the situation or whether it's just unreasonable to expect a human pilot to be ready to decisively react to runaway trim within a few seconds, at all times. The reason the stabilizer is moved with a jackscrew rather than hydraulics, to begin with, is that under ordinary conditions, you want the stabilizer to stay where it was in case of any failure. If it were moved by hydraulics, then a leak of the hydraulic fluid would leave the stabilizer flopping in the breeze, and the elevators, say they're on an isolated hydraulic system, would have no effect. Move the elevator up, and the entire stabilizer would just flop down and vice versa.
It might require careful gearing to maintain sync, but I suppose one could have two redundant jackscrews, each of which is sufficient to support the horizontal stabilizer on its own.
If you had two jackscrews working in parallel, you'd have two points of failure. If one screw stuffed, then it could jam and prevent the other from working. And the forces would be even higher trying to manually trim the thing. But... explosive bolts? :)
Indeed it’s a single point of failure, but then again, screws are fundamentally reliable things. Any automatic backup is likely to be less reliable than the screw and nut.
+1. There have been several warplanes that have returned home using the stabilizer to control the plane after the hydraulics/elevators failed.
I kinda doubt any plane would have a backup to the jackscrew, anymore than they have a backup if the wings fall off. The fact there's a backup (manual trim wheel) to the motors/electrical turning the jackscrew is great that it's there, at all. But apparently the manual trim might not even work under a high stabilizer loading, which an unusually high stabilizer load is what you get with the the new engine placement plus the abnormal MCAS response plus pilots not wanting the plane to crash.
Others have inquired, and I'm also curious about it, whether under such a high load if it's possible the motors won't even move the stabilizer. The report suggests that the pilots pressed the trim up button for 3 seconds at one point... but it only moved the stabilizer by 0.2 degrees. Math says 3 seconds should move it roughly 0.7 degrees! Maybe something was slipping, whether a belt/pulley or an actual clutch. Going back a few posts, this is another potential reason the pilots made only a small correction... because they realized the trim wasn't moving and something was slipping. And they were just smoking a belt/pulley or whatnot. In the original Jakarta crash a similar event was recorded. The last correction attempt before the crash was only a very small correction at the jackscrew. This might not have been due to switching pilots prior to this. Perhaps by this point, the belt that had already corrected this unusual condition 20 times had already started to fail, heating and stretching and smoking, having been pushed beyond its maximum expected load and duty cycle. So by the end, the motor is turning but the trim isn't moving, because the belt has become too loose and/or is melting at the surface. And now the jackscrew does what it's supposed to do. What it was designed to do. To stay put.
It's feasible that the pilots realized exactly what was happening, by the end, and that they knew exactly what had to be done. That their only hope was to temporarily reduce stabilizer load in order to trim the plane back up to stop losing altitude. But at the altitude they were at, they needed the speed of the motors to have any hope to trim the plane in time.... and hopefully not burn out the belt in the meantime, hence why they are not spamming the trim up button the entire time for naught. So when they finally attempted this, letting go of the yoke, MCAS decided to fire again at that moment just as they are pressing the up trim. Or maybe they were already too low/lost by the point they tried this. This would explain the severe downward angle at the end of each crash, in the last attempt to move the damn stabilizer. They might have realized they were stuck between a slow but sure death and a fast and nearly certain one with at least a sparkle of hope.
The trim wheel, itself, would most likely have a separate belt and pulley directly to the jackscrew. Then the motor has its own shorter belt and pulley. The manual method might be too slow, but if the motor belt is smoked, the manual trim wheel procedure might be the better chance. Ideally you could use both, but I think the speed of the motor would be too high to do both, simultaneously.
So ideally, perhaps. 1. Cut stab trim 2. Let go pressure on the yoke 3. Both pilots manually crank the wheel. 4. When static friction is broke and the wheel starts to turn, press trim up button while putting stab trim back on, and letting go the handles when the motor kicks on. 5. Resume pulling back on yoke. 6. cut stab trim when the the stabilizer is corrected. 7. Clip a few trees 8. Don't stall the plane during or after the hard nose up maneuver. (I think this last part is going to be extremely difficult after/during step 7, esp on a plane that is aerodynamically unstable in the specific way that the MAX is reported to be).
Yeah, that sounds pretty complicated. It would help if the pilots had telepathy and a third arm. And there might be a helpful other step, to cut back throttle to 50% in situation like this, where the plane is losing altitude and gaining speed. The higher speeds made this problem worse. Then putting throttle back up somewhere between 1 and 7, depending on the delay.
-
To be fair, it's not like Rockwell Collins doesn't have a solid reputation and history developing avionics for airliners. It actually seems to me rather reasonable that an aircraft manufacturer would buy from a company that specializes in avionics. Now, folks are right that a system like MCAS, designed to protect the airplane, is probably harder/more risky to farm out than, say, nav equipment, which has pretty much nothing to do with the airframe.
Does Airbus not farm out work to subcontractors?
I'm baffled at how such a shit engineering job could be done with MCAS.
Rockwell Collins has produced quite the turd, despite their "reputation" as having avionics experience. There are multiple fatal errors in the S/W. I see no evidence of expertise writing the S/W or testing or certifying it.
Honeywell (https://aerocontent.honeywell.com/aero/common/documents/myaerospacecatalog-documents/ATR_Brochures-documents/Airbus_A320_Brochure.pdf) did a lot on the Airbus 320.
I guess Boeing and Airbus are just doing the airframe design and systems integration.
-
I still don't know of any software bugs being admitted. The software might be doing exactly what Boeing specified, regarding the resetting after 5 seconds. Furthermore, it was after Boeing's own test flights that the response of MCAS was ultimately increased from 0.4 degrees to 2.5 degrees.
So it might have been a gradual creep into territory that eventually, in case of AOA failure, exceeded the plane's mechanical ability to move the stabilizer under that abnormal condition/load. Meaning AOA/MCAS failure can lead to a conditional failure/freezing of the stabilizer in a down position with little recourse unless you have several thousand feet of altitude you can afford to lose.
-
To be fair, it's not like Rockwell Collins doesn't have a solid reputation and history developing avionics for airliners. It actually seems to me rather reasonable that an aircraft manufacturer would buy from a company that specializes in avionics. Now, folks are right that a system like MCAS, designed to protect the airplane, is probably harder/more risky to farm out than, say, nav equipment, which has pretty much nothing to do with the airframe.
Does Airbus not farm out work to subcontractors?
Of course they all work with subcontractors and partners. Boeing, Airbus, Embraer, Bombardier Aerospace; none of them is writting a single line of code. None of them is designed anything electronic either.
The large aircraft manufacturers do not even design the complete airframe themselves.
:)
-
Rockwell Collins has produced quite the turd, despite their "reputation" as having avionics experience. There are multiple fatal errors in the S/W. I see no evidence of expertise writing the S/W or testing or certifying it.
You don't know any of this. For all you know, Collins wrote software that performs flawlessly with respect to the specification they were given. Maybe the engineering was fine and the spec was bad. We just don't know.
-
Na, Airbus and Boeing hire software engineers, look at their careers websites. Rockwell Collins seems to prefer new grads...
Is this is the mega corporation of the future?
Engineer-less, they just subcontract it all out.
Keeping with the MBA paradigm, get your nuts and bolts from the cheapest country and de-staff after the project is finished.
When the airplane(s) crash, the subcontractor's defense is "it wasn't in the requirements, nothing said to look at the second AoA sensor or let the pilot override it".
It's starting to smell like Volkswagen and Bosch, where Bosch made the ECU and software. Bosch wrote (requested) emissions defeat software for VW with a letter saying "for test purposes only" to absolve them. Bosch ended up paying $328M in that scandal.
Sure looks like MCAS went under the radar as something not critical, in order to avoid pilot training penalties, FAA scrutiny and going through basic safety tests.
-
Na, Airbus and Boeing hire software engineers, look at their careers websites. Rockwell Collins seems to prefer new grads...
You do realize Software Engineer in most of the world, including the US, is just a title. It doesn't mean much by itself, and some people with that title don't have a degree of any kind. Your work history, experience, and qualifications are what matter in the end.
I retired with the title of Senior Software Engineer. It is backed by a Computer Science degree in my case, but many of my colleagues had degrees in other fields or never finished their formal education.
-
Na, Airbus and Boeing hire software engineers, look at their careers websites. Rockwell Collins seems to prefer new grads...
They do no hire any software engineers to write code used in the commercial aircraft division. The software is bought, along with the hardware, from the various system suppliers.
:)
-
That's an issue - BSc in Comp Sci you are not bound by a code of ethics.
Engineering associations have been trying to include software in computer engineering, as something with formal documentation, calculations, that are subject to peer review. Just like a drawing that gets stamped, the PE stamps the software docs. I'm not sure it's realistic but something is needed to ensure critical software does not slither out the door.
The problem is you can never prove software correctness, it's impossible due to all the permutations of execution paths. IEC 61508 demands you've thought of the important ones, that kill people and that you have coverage and tested the modules and documented it all. I wonder if MCAS was even written to any S/W standard.
After these two airplane crashes, here it is the engineering profession that looks badly, as if they made stupid errors.
I suspect the executives and managers pushed too hard, circumventing regulatory processes etc. to hurry up the schedule and win the game.
-
Na, Airbus and Boeing hire software engineers, look at their careers websites. Rockwell Collins seems to prefer new grads...
They do no hire any software engineers to write code used in the commercial aircraft division. The software is bought, along with the hardware, from the various system suppliers. :)
I get what you're saying, that the S/W is a commodity item in avionics. Just like ordering a nut, bolt, rivet.
But S/W is still unique to the particular aircraft, somewhere, someone has to know the system and tailor it. And take responsibility.
It's the S/W requirements, testing and certification - all three failed. Some scumbag exec gets MCAS classified as "non-critical".
I can understand Boeing and Rockwell Collins engineers keeping quiet and not blowing the whistle. Finding another job in town would be very difficult and their employment agreements are surely overreaching.
-
The problem is you can never prove software correctness, it's impossible due to all the permutations of execution paths. IEC 61508 demands you've thought of the important ones, that kill people and that you have coverage and tested the modules and documented it all. I wonder if MCAS was even written to any S/W standard.
You can prove that a software is correct according to a specification, e.g. with systems like SPARK Ada. It is a lot of work, but it doesn't prove that the specification is right.
-
You can prove that a software is correct according to a specification, e.g. with systems like SPARK Ada. It is a lot of work, but it doesn't prove that the specification is right.
Exactly. Maybe the MCAS software specification was never designed to deal with erroneus flight data.
-
You can prove that a software is correct according to a specification, e.g. with systems like SPARK Ada. It is a lot of work, but it doesn't prove that the specification is right.
Exactly. Maybe the MCAS software specification was never designed to deal with erroneus flight data.
While it is possible to prove that a software meets the specification requirements. It is impossible to test/validate all the possible combinations of variables. Anything that is not specified in the requirements will react the way the programmer fantasized how he thought it should be. Also, every new software load always carry its own new set "undocumented changes".
This is true even with safety related software. And this is also true with flight control software. I am a speaking from personal experience.
I am not speculating that this is what happened with the MCAS. It seems that MCAS was piggy backed on top of the stick shaker system; where a single AOA sensor input is required for activation. The Boeing 737 was initially certified in 1967; it seems that anything could be certified 50 years ago. 50 years later, the Boeing 737 MAX is still riding on the initial 737 type certificate. The Boeing 737 type certificate data sheet is now at revision 61.
:)
-
You can mathematically prove software with the likes of Z Notation https://en.m.wikipedia.org/wiki/Z_notation
Problem is it takes a lot work/time and to do and needs to done for the full stack. There may be tools to help now, but 20+ yeas ago a simple loop resulted in pages of hand written equations. I hated learning it.
Or course it does not stop a badly written specification.
-
https://www.youtube.com/watch?v=9jNbayma9dM (https://www.youtube.com/watch?v=9jNbayma9dM)
-
^It started out as "they shoulda cut the stab trim." Now it's "they cut the stab trim, but they shoulda cut throttle." Next we'll find out "They shoulda cut stab trim, reduced throttle, and put a partridge in a pear tree." It's obvious that planes are only safe if this guy is your pilot.
AP cuts out. Sensor failures.
Pilot is trained to set pitch and throttle while figuring out the malfunctions. But pilot can't get the pitch up.
Speed increases, due to low AOA/pitch.
Cutting throttle would induce nose down. Need the throttle to maintain nose up, plus higher airspeed gives more lift at this low pitch.
But higher air speed plus the nose up force from the engines locks up the stabilizer.
At high enough airspeed with column pulled back, MCAS can easily move the trim down. But the pilot can't move the trim back up unless he does the "roller coaster maneuver." But the window for that maneuver is already gone. Plane going too fast at this point, and not enough altitude.
Sounds like a Chinese fingertrap. Or a Sandra Bullock movie with a bus.
In both crashes, the plane was going abnormally fast. IF this hypothetical can occur, and if the plane were to get into this spot, I wonder if extending the flaps would be a good idea. To increase the lift and drag* to counteract the increase in speed, while increasing lift to preserve/gain precious altitude, and without having to cut the engines as much (and getting the nose down force that would ensue). The flaps are retracted to increase fuel efficiency at cruise. But maybe there's an obvious reason that this is a bad idea, like the flaps would break off if you extended them at high speed.
*This is essentially what a high AOA does for the plane... to increase lift at the cost of increased drag. If you can't get the nose up, get the flaps out?
-
It seems like the Airbus A330-300 had a similar problem already many years ago, when false info were sent to the main flight control computers.
https://www.youtube.com/watch?v=2cSh_Wo_mcY (https://www.youtube.com/watch?v=2cSh_Wo_mcY)
-
^That was an actual software bug. The sensor malfunction created a situation that was undiscovered/untested and in this situation, the data got rolled over, or something like that, instead of clipped. The problem wasn't the sensor failure, it was an honest to goodness software bug. Notice that on this plane the FCC has control over the elevator, not just the rudder. The FCC can bounce people off the ceiling. In the 737, the FCC/MCAS can't do that.
With the MAX, the primary problem could be the aerodynamics of the plane and thrust axis of the engines combined with poor compromises in the implementation of the corrective automated response. The pilots of the MAX remained calm and did not panic, just as they were trained, calmly working through a checklist. Flying a big passenger jet, this should always be the correct attitude. But this situation could be more dire than Boeing has let on, and it might call for immediate and more drastic action before the problem spirals beyond a point of no return. And appropriate training.
I'm not suggesting one mistake is worse than the other. If the Airbus crashed, a software bug would have killed all the passengers, and they would have paid. But then they could fix the bug and carry on. The MAX already has bigger issues from a plane manufacturer/airline perspective.
-
ALL 737 planes have the flight characteristic that MCAS is designed to address. It’s merely stronger in the MAX than in earlier versions, so MCAS is there to compensate so that pilots don’t need to recertify. It’s incorrect to think of it as an unstable aerodynamic design, it’s just got a character that’s different enough that they couldn’t plausibly claim it under the same airworthiness certificate.
-
ALL 737 planes have the flight characteristic that MCAS is designed to address. It’s merely stronger in the MAX than in earlier versions, so MCAS is there to compensate so that pilots don’t need to recertify. It’s incorrect to think of it as an unstable aerodynamic design, it’s just got a character that’s different enough that they couldn’t plausibly claim it under the same airworthiness certificate.
You wrote "so MCAS is there to compensate so that pilots don’t need to recertify.", but I think you meant "...so that pilots don’t need to retrim".
:)
-
No - I think he is referring to the avoidance of having to acquire a new Type Rating.
-
The statements are not mutually exclusive. Both can be true. And apparently it works well when nothing is broken. The problems are all in the area of inadequate redundancy, fault-handling and fallback behavior.
-
No - I think he is referring to the avoidance of having to acquire a new Type Rating.
Exactly this. Without MCAS, the 737 MAX would have different stabilizer trim needs, thus requiring a new type rating for the aircraft and thus requiring pilots to acquire it.
The statements are not mutually exclusive. Both can be true. And apparently it works well when nothing is broken. The problems are all in the area of inadequate redundancy, fault-handling and fallback behavior.
Exactly.
-
The emergency procedure may not be adequate.
If you look at Air Alaska 261, the plane was put in a similar situation. It started out with a seized jackscrew nut. The place where the trim seized, the pilots had to pull up on the yoke with ~10 lbs of force to keep the plane level.
After futzing with the trim controls on/off for 15 minutes, the nut finally unseized. But because it was stripped and because they were pulling up on the yoke, the stabilizer moved down, rapidly, where it jammed again.
The pilots eventually regained level flight by pulling on the yoke with 140 lbs of force. They were able to communicate with ATC and were preparing to attempt a landing at LAX.
But the jackscrew was not designed to handle this "unusual position" of the stabilizer and the entire jackscrew assembly broke from the stress. The pilots elevator controls were now useless. MCAS malfunction puts the stabilizer into an "unusual position." Not being able to physically turn the trim wheel, manually, seems like the pilots need to workout. But this is enough force to actually break the entire mechanism (on a different plane, of course).
Roller coaster maneuver is now known to many more pilots, and hopefully there is room to do it, if needed.
-
Airbus' use of three AoA sensors has had incidents and crashes.
Two of the three AoA sensors agree but are both faulty, example is a pair seizing due to ice, and then stall protection activates.
XL Airways Germany Flight 888T (https://en.wikipedia.org/wiki/XL_Airways_Germany_Flight_888T) did not make it. BEA report (https://www.bea.aero/docspa/2008/d-la081127.en/pdf/d-la081127.en.pdf) with AoA tests showing sticking from moisture in the bearings freezing.
Lufthansa Flight LH1829, (https://aviation-safety.net/wikibase/wiki.php?id=171411) the fix was to break AoA1 and AoA2 consensus by shutting off Air Data Reference unit (ADR) 2.
AoA3 was reading correctly, so all that was left is a disagreement.
There's a real need to over-ride anti-stall automation, and not just switch it off leaving you in a dive.
I wonder what Boeing's new MCAS software does, given it is full of unicorns and rainbows and the 96 test flights so far, and many billions of dollars and 346 lives lost.
We all know end-use testing of software is not proof of correctness, 1,000 flights would still say nothing really. How does it do with a blocked pitot tube or airspeed sensor problems? All inputs to the S/W module have to be considered going faulty.
I have zero faith in Boeing or Collins being able to do a proper fix. Good luck selling it to the globe.
-
It's interesting that in the Lufthansa flight, individual AOA sensor data can be switched off. So if the pilot discovers two sensors out of three are broken, he can potentially switch off the ones that are faulty based on what he is perceiving. This was done during a call to the maintenance department for the airliner, so it's not necessarily a "memory item," but it is at least possible. Maybe Boeing will be able to add this ability to the 737. In ET302, both pilots called out "left alpha vane," so they were aware not only of an AOA disagree; they actually recognized which sensor was incorrect.
In the first link, 888T, the faulty AOA sensors were caused by improper maintenance. And it appears the main reason the plane ultimately crashed is because the pilots were testing the stall warning, but they were not aware that the AOA sensors were malfunctioning. And unfortunately, they did this test at a low altitude after being denied the air space they wanted. Trusting safety technology a bit too much, maybe. The pilots obviously trusted the plane and were demonstrating its condition to the leasor. And maybe they had done this test, previously, in preparation for this demonstration flight. But they didn't take into consideration that it had just had a complete overhaul.
-
It's interesting that in the Lufthansa flight, individual AOA sensor data can be switched off.
They didn't have the precision to turn off individual sensor data. They had the ability to turn off one of the computers that handled that sensors data, which disabled about a third of the various sensors on the aircraft. Basically masking a sensor fault with an intentional computer fault. Not something to be done lightly, especially if one isn't sure of their diagnosis/solution.
-
Isn't there one option missing? In case the plane has a relative high speed and thus the manual trim is hardly usable because of the high forces on the elevator, the pilot would benefit by switching off the MCAS system/correction but not the electrical activated trim switches on the joke.
PS On the MCAS side input "rules" on the sensors were missing. A 70 degree AOA should never be accepted at flying speeds
-
PS On the MCAS side input "rules" on the sensors were missing. A 70 degree AOA should never be accepted at flying speeds
At 200 knots wind speed and AOA of 70, that would mean the plane is going roughly 585 knots, true vector speed. And that would make the plane's speed in the belly (relative downward) direction 550 knots. I wonder if the wings would stay on. Even if they did, the reading is obviously invalid if it were to remain stable at 70. The plane would be in the middle of a somersault, if the reading were correct. And stabilizer will be useless, anyhow, while the plane is spinning... even if the plane was temporarily "flying" like a pancake, it would not be controllable at that time.
Even with a lack of other sensor data, I wonder if some sort of tracking over time might be useful. If the AOA changes faster than possible (or remains impossibly stable in an extreme condition), it might be able to be noticed by the FCC that the sensor is screwy, or the plane is already crashed.
To put 70 degree AOA in perspective: in AF447, the plane never exceed 40 degrees AOA while in a stall for 3 minutes... while the PF was actively pulling back on the stick.
-
Isn't there one option missing? In case the plane has a relative high speed and thus the manual trim is hardly usable because of the high forces on the elevator, the pilot would benefit by switching off the MCAS system/correction but not the electrical activated trim switches on the joke.
While your point has some validity, it is that sort of difference in the function of an aircraft that can lead to a separate Type Rating. Establishing a new Type Rating means that any pilot that wants to fly such an aircraft will need to go through the full rating exercise. This takes time, costs money and restricts the range of aircraft that an airline's pilots can fly unless they get the additional type rating. It also means that pilots with more than one Type Rating have to keep each of them up to standard with ongoing training and assessment.
The objective of any new version of an aircraft is to keep it the same (as much as they possibly can) as previous versions - in the skills required to fly it. This is why they still have the "No Smoking" switch on the 737NG models - even though it hasn't been active for years.
-
Isn't there one option missing? In case the plane has a relative high speed and thus the manual trim is hardly usable because of the high forces on the elevator, the pilot would benefit by switching off the MCAS system/correction but not the electrical activated trim switches on the joke.
surprising isnt it? engine and attitude can be controlled either manually or automatically at comfortable strength, ie servo or hydraulic booster activated on both mode. but not the elevator trim wheel, in manual mode, you need conan barbarian strength to rotate those wheel at probably hundreds of rotation from one end to the other.
-
Had the pilot been a Sully, he would never have allowed the stabilizer to go full nose down (*), but these were young, "playstation" kind of pilots, they got lost the moment their xbox went nuts, and failed to keep under control 1) the speed (**) and 2) the control surfaces, a.k.a. the #1 rule: fly the plane.
(*) There's a dial next to the stabilizer wheel => you can see the angle and you are seeing it spinning in the wrong direction to further nose down => a self confident Sully kind of pilot would have just grabbed and stopped it immediately. The reason why it's got a clutch is to allow you to do exactly that.
(**) They totally neglected air speed, too.
-
Had the pilot been a Sully, he would never have allowed the stabilizer to go full nose down (*), but these were young, "playstation" kind of pilots, they got lost the moment their xbox went nuts
I think you need to sit down and shut up, old man, and learn about what pilots actually learn before you go badmouthing them.
-
https://leehamnews.com/wp-content/uploads/2019/04/Preliminary-Report-B737-800MAX-ET-AVJ.pdf
What I find very curious in this preliminary report:
There are a couple instances where the report states the duration of the MCAS trim adjustments in seconds and in units.
But there are NO instances, anywhere in this doc, were the duration of the pilots' manual power trim inputs are ever reported. The only thing that is reported is the corresponding movement of the stabilizer.
In addition:
At 05:40:41, approximately five seconds after the end of the ANU stabilizer motion, a third instance
of AND automatic trim command occurred without any corresponding motion of the stabilizer,
which is consistent with the stabilizer trim cutout switches were in the ‘’cutout’’ position
This statement suggests that
1. The data recorder doesn't know the position of the stab cutout switches
2. The data recorder doesn't know if/when the trim motors are actually powered or not; the conclusion is made based on the actual movement of the stabilizer.
So we can't know if the power trim was working, properly, in this plane under these conditions, from the info in this report. Either this info was omitted/withheld intentionally, or it was not recorded.
AFAIC, it is completely possible that the pilots did not make appropriate trim inputs under the conditions. It is also completely possible that they did, but the stabilizer did not make the corresponding change. It is further possible they grabbed the trim wheel and successfully stopped the wheel from turning further down... but the stabilizer/jackscrew moved, anyway. Pulling back on the yoke puts a high force that wants to push the entire stabilizer into a further nose down position (ref Alaska Air 261)*. AFAIC, this mechanism is probably belt driven, and at some point belts slip. Gears or chains are possible, but not likely, IMO (and a snapped jackscrew or chain is also no good). There is potentially a point where cutting stab trim is the only way to prevent the MCAS from moving the trim further down despite grabbing the wheel, physically.... and that there is no way to move the trim back up without doing a roller coaster maneuver.
*I picture the stabilizer rotating around an axle that is near its midpoint. As long as the elevator is neutral, it doesn't matter what load is on the stabilizer; it can still rotate freely under power or manual trim. But an extreme elevator position can put enough torque that the stabilizer cannot be rotated against this force, anymore... though it might still be possible that the motor (MCAS) could turn the stabilizer in the other direction.
-
Had the pilot been a Sully, he would never have allowed the stabilizer to go full nose down (*), but these were young, "playstation" kind of pilots, they got lost the moment their xbox went nuts
I think you need to sit down and shut up, old man, and learn about what pilots actually learn before you go badmouthing them.
And you should stop watching the TV because there are professional pilots saying just that in forums all over the internet, e.g. at pprune.org
-
https://www.youtube.com/watch?v=zGM0V7zEKEQ (https://www.youtube.com/watch?v=zGM0V7zEKEQ)
-
^I'm curious where this guy gets his information. How does he know this stuff? Particularly the part about pilots not being able to tell the difference with MCAS off... and why can you disable MCAS in a simulator and not in an actual plane?
Anyhow
1. "MCAS isn't antistall... it just gives the plane a little nose down nudge to make it handle like the NG."
10 seconds and 2.6 degrees of trim every 5 seconds is not a small nudge.
2. "This proved too big. In simulator testing it (when fired erroneously, I presume) can put the plane into an unrecoverable situation in as little as 40 seconds."
According to the Seattle Times article, Boeing initially told FAA that the stabilizer adjustment was only 0.4 degrees. But they had to increase it based on real test flights. Boeing didn't increase this response, by over 4x without informing the FAA, for no good reason.
At an actual high AOA, that huge amount of trim has been (presumably) shown to actually be needed in real test flights. But when it happens erroneously, at lower AOA, this adjustment is obviously enormous. This is to be expected due to how the aerodynamic problem caused by the engine manifests. The nose up force increases as the AOA increases. At high AOA, you need an extreme stabilizer position. At normal AOA, this stabilizer adjustment will be ridiculous. Is what it is. "Small nudge" is optimistic.
-
Only Boeing shills will push the "blame the pilots" narrative.
No system should be so obfuscated, undisclosed to pilots, and ultimately such a shit design.
"... Boeing is now working on and testing changes to the software “because the original software was designed in a hideous manner.” as the Pilots Association says. “MCAS was a monster”.
How about the class action lawsuits against Boeing:
"...claims the plane maker “effectively put profitability and growth ahead of airplane safety and honesty.”
"Boeing withheld necessary safety features from the Boeing 737 Max unless airlines purchased them as ‘extras’ or ‘optional features’ in order to keep the price down” to compete with Airbus.
How about Trump desperately tweeting “FIX the Boeing 737 MAX, add some additional great features, & REBRAND the plane with a new name.”
Anything to save the huge political donations Boeing gives the Republican Party, and the thousands of jobs at risk.
He has no idea that it takes a very long time to engineer out the bullshit and may not even be possible, if the aircraft needs hardware changes.
-
Oh, it is possible that it was pilot error, but we don't know that. As a conspiracy theorist, I can imagine
1. Jakarta was potentially a true accident and might have been partly due to pilot error.
2. ET302 was crashed intentionally. I can't guess the motive other than some damage to the US and/or the UN. (Many UN members were onboard). And the pilots were both in their twenties... young men are most susceptible to being martyrs for idealistic reasons. You could even wonder if it really comes down to money... Airbus investors involved.
This is seemingly ridiculous, but wherever hundred of billions of dollars hang in the balance, every angle must be investigated to the very end. Let alone the deaths of the 150 people onboard.
-
They and Boeing, both are to blame. It's hard to have to blame the poor dead pilots too, but they didn't do it right. Sorry but that's the sad truth. Hundreds of lives lost due to 1) Boeing and 2) two young pilots who should have known better after the Lion Air 610 crash.
-
It's hard to have to blame the poor dead pilots too, but they didn't do it right. Sorry but that's the sad truth.
If you know that, great. I don't know it, despite anything you or any "real" pilot has posted. Jakarta: yeah, let's say they shoulda cut the stab trim. But even if the pilots had cut the stab trim, it still doesn't mean the plane would not have subsequently crashed.
-
They were incapable to (un)trim and to keep the speed within limits, when the means to untrim and to control the speed were there. Had your son been in that plane, you'd call that a fail, wouldn't you?
-
They and Boeing, both are to blame. It's hard to have to blame the poor dead pilots too, but they didn't do it right. Sorry but that's the sad truth. Hundreds of lives lost due to 1) Boeing and 2) two young pilots who should have known better after the Lion Air 610 crash.
You can't move the stabilizer once you shut off power. You get a few seconds after switching stab trim power on, until MCAS takes over again. I think this is why ET302 kept flipping power on and off, trying to stop the dive.... after the emergency procedure failed them. The manual trim wheels need the Hulk to turn them.
I can't fault the pilots for something so complicated, secretive and ultimately a futile endeavour.
-
They and Boeing, both are to blame. It's hard to have to blame the poor dead pilots too, but they didn't do it right. Sorry but that's the sad truth. Hundreds of lives lost due to 1) Boeing and 2) two young pilots who should have known better after the Lion Air 610 crash.
You can't move the stabilizer once you shut off power. You get a few seconds after switching stab trim power on, until MCAS takes over again. I think this is why ET302 kept flipping power on and off, trying to stop the dive.... after the emergency procedure failed them. The manual trim wheels need the Hulk to turn them.
I can't fault the pilots for something so complicated, secretive and ultimately a futile endeavour.
No, no... please re-read the preliminary report it's here: https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2321457/#msg2321457 (https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/msg2321457/#msg2321457)
At 5:40:00 they should have corrected trim with the yoke's trim button (electrical trim) and then flip the cutout switches to off for the rest of the flight and they would all be still alive.
-
As a conspiracy theorist,
https://en.wikipedia.org/wiki/Conspiracy_theory (https://en.wikipedia.org/wiki/Conspiracy_theory)
A conspiracy theory is the fear of a nonexistent or alleged conspiracy or the unnecessary assumption of conspiracy when other explanations are more probable. Evidence showing it to be false, or the absence of proof of the conspiracy, is interpreted by believers as evidence of its truth, thus insulating it from refutation.
closely related to, in more modern terminology:
https://www.urbandictionary.com/define.php?term=Trolling (https://www.urbandictionary.com/define.php?term=Trolling)
Trolling – (verb), as it relates to internet, is the deliberate act, (by a Troll – noun or adjective), of making random unsolicited and/or controversial comments on various internet forums with the intent to provoke an emotional knee jerk reaction from unsuspecting readers to engage in a fight or argument
The real question is how useful and/or desirable this behavior is.
-
At 5:40:00 they should have corrected trim with the yoke's trim button (electrical trim) and then flip the cutout switches to off for the rest of the flight and they would all be still alive.
GoJ: I realize the thread was started 5 months ago, and that it started due to this Jakarta crash. But the big hubbub is over the more recent Ethiopian airlines crash that occurred just 5 months after Jakarta. And AFTER airlines and pilots were given specific training on how to handle an AOA sensor failure causing erroneous MCAS activation. ET302 pilots reportedly received this training.
Nusa, lol. :palm:
-
GoJ: I realize the thread was started 5 months ago, and that it started due to this Jakarta crash. But the big hubbub is over the more recent Ethiopian airlines crash that occurred just 5 months after Jakarta. And AFTER airlines and pilots were given specific training on how to handle an AOA sensor failure causing erroneous MCAS activation. ET302 pilots reportedly received this training.
The report I'm referring to is of the ET302 crash, at 5:40:00 they should have (un)trimmed but they did not do it. That was their first chance to save the plane, but not the only one nor the last.
-
^My bad, I just read "jakarta" in that link and thought you were talking about the other crash.
As for "they shoulda untrimmed," if you look carefully at this report, there's nothing in it that proves the pilots did not do what you are suggesting they should have done. The report does not include the duration of the pilots' trim inputs. Only the resultant change at the stabilizer. It is quite possible that the pilots pressed the button appropriately, but the stabilizer did not move the amount that would be expected, due to extreme elevator load. It appears they may have "neglected" to switch the power back off, though.
After the Alaskan Airlines 261 accident, the NTSB has suggested that in a case where the trim is not working, properly, that no further attempt should be made to correct the trim. So what they "should have" done is not exactly clear without having been there, unless you have a crystal ball. Even if there were able to maintain level flight at that point, with no further trim adjustments, that doesn't guarantee the plane could bank to return to the airport without losing too much altitude or that they could land the plane, safely, in this condition. They may have had to land at a much higher than normal speed, and they might not be able to stop on the runway or they might break the front landing gear. Depending on the airport, this might mean crashing into buildings or a mountain... or falling off the edge of a cliff. This airport has been described as a shoebox in the mountains.
*I find it rather curious that the report states the duration of the MCAS response a couple of times, but nowhere does it state the length of trim input from the pilots. I find it hard to believe this is not recorded by the black box. Perhaps the response was not appropriate, and the airline is intentionally omitting this information to keep this data hidden for a bit longer.
-
Had the pilot been a Sully, he would never have allowed the stabilizer to go full nose down (*), but these were young, "playstation" kind of pilots, they got lost the moment their xbox went nuts
I think you need to sit down and shut up, old man, and learn about what pilots actually learn before you go badmouthing them.
And you should stop watching the TV because there are professional pilots saying just that in forums all over the internet, e.g. at pprune.org
Aww, honeybear, I literally do not even have TV. (I do not have cable or antenna, nor do I subscribe to any internet TV service. Just netflix for movies, and youtube.)
My point was, at no point EVER has flying been like video games. Are younger pilots more inexperienced? Sure. Age lets you gain experience. But it’s complete and utter bullshit to act as though pilots today are not trained well. If you actually followed working airline pilots, and not just general aviation pilots, you’d know this.
-
... and why can you disable MCAS in a simulator and not in an actual plane?
If you just think for a second, that should be extremely obvious.
Simulators are used for training - and that includes training for adverse situations. Flick a switch and you can have an engine fire to deal with - or a failed instrument - or a faulty hydraulic system. I don't think these will be options on a real plane.
Same way you could flick a switch to kill the MCAS, but not affect anything else.
Simples.
-
Had the pilot been a Sully, he would never have allowed the stabilizer to go full nose down (*), but these were young, "playstation" kind of pilots, they got lost the moment their xbox went nuts
I think you need to sit down and shut up, old man, and learn about what pilots actually learn before you go badmouthing them.
And you should stop watching the TV because there are professional pilots saying just that in forums all over the internet, e.g. at pprune.org
I also think that bringing up the pilot’s age can't serve for any judgement.
Experienced pilots make fatal mistakes as well -> Captain Lutz with close to 20k hours flight experience crashed Crossair 3597
https://en.wikipedia.org/wiki/Crossair_Flight_3597
-
istr that brown guy admitted they used to leave auto throttle on because they were so much comfortable with it, so he admitted he is one of the lazy arse. anyway, everybody can pick side but i still stand with my logic, forget about what the "PAID" pilots said... same pilots before, regardless of experienced or new... this tragedies never happening before, esp on experienced pilots... ok some pilots managed to disable MCAS and live the life to tell the story. but this is not an excuse of why they can and others cant. again, this type of bugs never happening before. so either its boeing, faa or anything on their side who have introduced this bugs into the new airplane, hence it is them who are at fault. now you people can continue killing (bashing) each other.
-
Interesting post on reddit from an ex- Boeing employee :
https://www.reddit.com/r/videos/comments/bdfqm4/the_real_reason_boeings_new_plane_crashed_twice/ekyyd9g/ (https://www.reddit.com/r/videos/comments/bdfqm4/the_real_reason_boeings_new_plane_crashed_twice/ekyyd9g/)
-
It's my understanding that in the more recent 737-8 max incident the pilots failed to follow the first item in the aviate, navigate, communicate checklist. The aircraft was at some absurd speed, >500kts while they tried to recover the aircraft.
The swiss cheese model really stinks after these two incidents
-
Interesting post on reddit from an ex- Boeing employee :
https://www.reddit.com/r/videos/comments/bdfqm4/the_real_reason_boeings_new_plane_crashed_twice/ekyyd9g/ (https://www.reddit.com/r/videos/comments/bdfqm4/the_real_reason_boeings_new_plane_crashed_twice/ekyyd9g/)
If true, that is horrible!
I have similar experiences with car companies around the world but getting stranded with a car is nothing compared to falling out of the sky.
-
My point was, at no point EVER has flying been like video games. Are younger pilots more inexperienced? Sure. Age lets you gain experience. But it’s complete and utter bullshit to act as though pilots today are not trained well. If you actually followed working airline pilots, and not just general aviation pilots, you’d know this.
From that thread at reddit that Mike has posted above:
AA had a great series of training videos posted on YouTube under the flightcrewguide.com account, but unfortunately the one named "Children of Magenta" was deleted. This one was all about the instructor warning against the trends he was seeing of airlines training people to be computer operators first and pilots second. He related a story about how he'd take people up in a simulator inline with a runway and told to land the plane. He gave them a perfect sunny day with not a cloud in the sky, the most perfect conditions there could possibly be, and then introduced some sort of small problem causing them to slightly begin to deviate from expected flight. New pilots would immediately drop down to the computer and start typing away, making sure they've got the right parameters entered in, frantically trying to figure out why the computer wasn't flying the plane right, and eventually they'd get things under control.
He'd then pause the simulation and go "that's OK, but did you ever think of... flying the plane?" In each scenario the pilots were so caught up with trying to figure out what the autopilot or autothrottle or whatever else was doing but they never thought to look out the window, grab the controls, and land the plane.
I don't want an automation engineer behind the controls, I want a fucking pilot
-
As a conspiracy theorist,
https://en.wikipedia.org/wiki/Conspiracy_theory (https://en.wikipedia.org/wiki/Conspiracy_theory)
Please dont cite Wiki as a definitive fact source.
Conspiracy theorists is one or a group of people who theorises/hypotises/analyzes the facts they found on
another group of people who conspire/d to achieve something such as the Clinton Charity fraud or JFK murder.
Wikipedia is full of trolls who wants to bend the content their way.
-
AA had a great series of training videos posted on YouTube under the flightcrewguide.com account, but unfortunately the one named "Children of Magenta" was deleted. This one was all about the instructor warning against the trends he was seeing of airlines training people to be computer operators first and pilots second. He related a story about how he'd take people up in a simulator inline with a runway and told to land the plane. He gave them a perfect sunny day with not a cloud in the sky, the most perfect conditions there could possibly be, and then introduced some sort of small problem causing them to slightly begin to deviate from expected flight. New pilots would immediately drop down to the computer and start typing away, making sure they've got the right parameters entered in, frantically trying to figure out why the computer wasn't flying the plane right, and eventually they'd get things under control.
He'd then pause the simulation and go "that's OK, but did you ever think of... flying the plane?" In each scenario the pilots were so caught up with trying to figure out what the autopilot or autothrottle or whatever else was doing but they never thought to look out the window, grab the controls, and land the plane.
To play devils advocate: Sounds good to me? Esp the part about eventually getting things under control. You take that pilot that grabs the stick and doesn't know how to use the automation. That is great until the first day with no visibility. We increasingly need pilots that can tackle abstract computer/software problems in emergencies without calling tech support. The automation is there for safety reasons, not for convenience so the pilot can make coffee instead of flying the plane. The layers of abstraction are absurd, if you watch the MP video of a simulation of an untrained passenger landing a plane, directed by a voice over the radio. Flipping through menus and clicking buttons, lol. It looks awful, but if I don't suppose it would be allowed to get that way if it didn't hold up to be statistically safe.
The pilot should doubt his own human part of the equation, sometimes, and double check his settings if given the time/conditions. You could think that this is a great opportunity to take the plane in, manually, being under perfect visual conditions. It's also perhaps a good opportunity to test your command of the computer menus and settings under some level of duress, even if manually landing the plane is trivial under these conditions; that might also save your life someday.
We need pilots who trust the automations and sensor information as much as their own ability to input the information correctly the first time and/or to fly the plane, manually. Rather than (sometimes incorrectly) abandoning the automation at the first scare. It is silly to trust Tesla autopilot with your life, but at some point it is perhaps going to be safer than a human driver. It's possible that airplanes have already gotten to that point. Even the best pilots in the world have probably almost killed themselves more than once through errors that a computer would not have made. (Famous fly-by story of a top SR-71 pilot comes to mind). It's just human nature that after we do something many times without dying, our comfort zone increases. Most pilots have had close calls or gotten lucky and have learned from that. Airlines can't afford to let pilots learn the hard way with 100 million dollar airplanes. Increasingly, pushing buttons and flipping through menus IS flying the airplane.
There is a good argument that Sully made a bad decision, BTW. He executed the water landing perfectly, though, and that counts for a lot.
-
We increasingly need pilots that can tackle abstract computer/software problems in emergencies without calling tech support.
Careful how this comes across. We do not need pilots that can take on the task of identifying the cause of the problem. That will take time and even if the cause is discovered, it may not help with resolving the problem. What we DO need are pilots that can deal with emergencies and take timely action in order to get the aircraft safely on the ground.
-
"Bjorn’s Corner: Why did Ethiopian Airlines ET302 and Lion Air JT610 crash?"
https://leehamnews.com/2019/03/22/bjorns-corner-the-ethiopian-airlines-flight-302-crash-part-2/
The similarity with Lion Air JT610 crash
The data from the Flight Data and Voice Recorders have been read out by the French Bureau d’Enquetes et d’Analyses (BEA) and sent to the Ethiopian authorities, who lead the investigation.
The Ethiopian transport minister said the data shows “clear similarities” to the Lion Air crash six months ago.
The conclusion is then we have another Angle of Attack (AoA) fault of 22 degrees, which invokes stall warning at rotation and subsequently MCAS trimming once flaps are retracted.
The trim jack of ET302 was also found with the trim position full nose down. Why the crew didn’t switch the trim system off we will know in due time.
How JT043 was saved
We now know the crew which did switch the trim switches off, the flight before JT610, did so because a third Pilot from the sister company Batik air, flying clap seat in the JT043 cockpit, could observe the cacophony of actions an AoA disagree of 22 degrees invokes.
He had a free head as he had no flight role. He was the one which proposed switching the trim switches off after having seen the usual trimming from Speed Trim after takeoff not stopping. It was also trimming in the wrong direction (Speed Trim helps the Pilot with the feel of the aircraft by trimming in the background during takeoff and initial climb, mostly trimming nose up).
The Captain switched the trim off, check how this felt, then switched it on again and finally decided the switches off were better. He did not reach this conclusion because he observed a trim runaway.
The constant trimming in the background when flying manually is a normal state for a 737, especially after takeoff. Speed Trim is at work. Trim Runaway is when the trim is running full speed in one direction only. This did not happen, neither when Speed Trim was active (before flaps up) nor when MCAS took over.
What the JT610 Pilots worked on until they crashed
We now know the Captain of JT610 was calm during the fatal flight. He flew the aircraft and asked the First Officer (FO) to go through the Quick Reference Handbook (QRH) which contains the Emergency checklists, to find the relevant emergency procedure for the strange behavior of the aircraft.
As the FO couldn’t find anything which fitted to their situation, the Captain handed the FO the control of the aircraft (after line A in Figure 2) and took the QRH to see if he could find a cure for the sick aircraft.
The Captain had successfully counter trimmed MCAS 21 times and probably told the FO to do the same. The FO trimmed, but he did it in too short periods, B in Figure 2. Gradually the MCAS got the trim moved more and more nose down (the top A in Figure 2).
Figure 2. The Flight Data Recorder traces released to the parliament for JT610 crash. Source: Indonesian authorities.
I know from pilots who have tested to fly a 737 in the simulator that you can keep the nose up with the Pilot controlled elevator, even against a full nose down trimmed horizontal stabilizer.
So why did JT610 and ET302 dive and crash? The pilots held against as the simulator pilots did? We know this for sure for JT610 where we have the Column force traces (C in Figure 2) and can assume this for ET302.
MCAS didn’t crash the aircraft, Blowback did.
The cause of the final dive has bugged me since the Flight Data Recorder (FDR) traces from JT601 were released. I couldn’t find a plausible answer. I tried different theories but none was convincing.
This week a poster in the Professional Pilot’s forum revealed the Boeing 737 has a blowback elevator problem at high dynamic pressures (thanks Dominic Gates of the Seattle Times for pointing me to this post). Now the penny dropped.
I know all about blowback problems of elevators. It was the most dangerous shortcoming of the fighter I flew, the SAAB J35 Draken. Even more dangerous than its famous “Super stall”, a Pugachev Cobra like deep stall behavior the aircraft would only exit from if you “rock it out” of the stall (more on this some other time). While “Super stall” is scary, Blowback is deadly.
Blowback means the elevator is gradually blown back to lower and lower elevation angles by the pressure of the air as the speed increases. The hydraulic actuators can’t overcome the force of the air and gradually back down if the force of the air grows too strong.
If a blowback phenomenon is confirmed for the 737 at the speeds and altitudes flown, this is what happened at the end of the JT610 flight and probably ET302.
When a pilot experiences a stall warning like a stick shaker, his reaction is to lower the nose and increase the speed. He wants to build a margin to an eventual stall. If he simultaneously has “Unreliable airspeed” warning, the built margin will be larger.
In both of these cases, the pilots are flying faster than normal at the low altitudes they flew (5,000ft pressure altitude for JT610, 9,000ft for ET302). This is to build a safety margin while sorting out stall warning and flight control problems.
As they pass 300kts they enter the area of elevator blowback according to the poster. As the FO is losing the nose due to short counter trims against MCAS at B in Figure 2, the speed increases at the same time as more angle is required to keep the nose level.
As blowback stops him from getting the elevator angle he needs, the aircraft started a dive at D and speed increased further. The FO pulls harder but nothing happens (C in Figure 2). The Captain now stops reading the QRH and pulls as well. It’s too late. The elevator is gradually blown down to lower and lower angles as the speed increases and the dive deepens.
What could have been done?
The only remedy to the blowback induced dive would have been a full nose up trim application, for a long time (throttles to idle and air brake would also have helped). But the reaction to trim is slow and the aircraft was now heading for earth. The reflex is not to trim but to pull for all there is, by both pilots, you have seconds to stop the dive. It didn’t help.
If this is confirmed as the scenario for the end of both JT610 and ET302 I wonder why the danger of flying to fast at low altitude, while sorting out a raiding MCAS, was not communicated when the MCAS Airworthiness Directive was released after the JT610 crash.
MCAS forcing the horizontal stabilizer to full nose down should not have doomed JT610 or ET302. Their applied speed margins did.
The JT610 crew knew nothing about MCAS and a potential blowback problem. The ET302 crew knew about the MCAS problem but not about the danger of flying to fast while sorting MCAS.
I have checked with longtime pilots of the 737. They have not heard of a Blowback problem when flying at elevated speeds at low altitude. And before MCAS there was no reason to, it was beyond normal flying practice.
But the JT610 investigators saw what can happen when you run into the MCAS rodeo. Why didn’t they warn to keep speeds within normal speed range for the altitude?
-
From that: "...the Boeing 737 has a blowback elevator problem at high dynamic pressures".
It seems to be like a "super stall" except you are in a fast dive and the elevator is ineffective? ET302 stayed at 94% throttle (N1) throughout, and 500kts at the end, it was fast.
"The new {MCAS} software load [P12.1] has triple-redundant filters that prevent one or both angle-of-attack (AOA) systems from sending erroneous data to the FCCs that could falsely trigger the MCAS. It also has design protections that prevent runaway horizontal stabilizer trim from ever overpowering the elevators. Boeing showed pilots that they can always retain positive pitch control with the elevators, even if they don’t use the left and right manual trim wheels on the sides of the center console to trim out control pressures after turning off the trim cut-out switches.
"Most important, the MCAS now uses both left and right AOA sensors for redundancy, instead of relying on just one. The FCC P12.1’s triple AOA validity checks include an average value reasonability filter, a catastrophic failure low-to-high transition filter and a left versus right AOA deviation filter. If any of these abnormal conditions are detected, the MCAS is inhibited.
Three secondary protections are built into the new software load. First, the MCAS cannot trim the stabilizer so that it overpowers elevator pitch control authority. The MCAS nose-down stab trim is limited so that the elevator always can provide at least 1.2g of nose-up pitch authority to enable the flight crew to recover from a nose-low attitude. Second, if the pilots make electric pitch trim inputs to counter the MCAS, it won’t reset after 5 sec. and repeat subsequent nose-down stab trim commands. And third, if the MCAS nose-down stab trim input exceeds limits programmed into the new FCC software, it triggers a maintenance message in the onboard diagnostics system."
https://aviationtroubleshooting.blogspot.com/ (https://aviationtroubleshooting.blogspot.com/)
-
GoJ, it sounds like you are beginning to entertain the possibility the pilots did not screw up? I was wondering why the pilot can overcome the stabilizer at low speeds without any problem but this that changes at higher speed. I assumed it was because at a certain speed, the airflow over the highly angled elevator starts to delaminate. But now there's another potential reason to consider.
And before MCAS there was no reason to, it was beyond normal flying practice.
This is still something that should be investigated and disclosed, regardless if MCAS can or cannot put the plane here, after the changes. Whether or not it is beyond normal, it ought to be something that that pilots are aware of, methinks.
The conclusion is then we have another Angle of Attack (AoA) fault of 22 degrees, which invokes stall warning at rotation and subsequently MCAS trimming once flaps are retracted.
This is another reason why extending the flaps might have helped, although the pilots of the Jakarta flight would not have been aware of this reason. And it seems doubtful that pilots of a 737 should/could do things that are not explicitly in their training. Treating the flaps like a "takeoff/landing" thing, only, seems like it is perhaps short-sighted, IMO. Changing the lift and drag of the wings should be an inherently useful feature in other scenarios, in my mind... the mind of a non-pilot.
We now know the crew which did switch the trim switches off, the flight before JT610, did so because a third Pilot from the sister company Batik air, flying clap seat in the JT043 cockpit, could observe the cacophony of actions an AoA disagree of 22 degrees invokes.
He had a free head as he had no flight role. He was the one which proposed switching the trim switches off after having seen the usual trimming from Speed Trim after takeoff not stopping. It was also trimming in the wrong direction (Speed Trim helps the Pilot with the feel of the aircraft by trimming in the background during takeoff and initial climb, mostly trimming nose up).
This is the one documented case that was fixed in time. I have heard others state there were multiple cases where (Americian) pilots have cut the stab trim in time, but I have not seen any proof of this. I'm also skeptical because AOA sensors are supposed to be pretty reliable, and the plane has only flown for a couple of years.
Floorbydust: good find on the details on the software-side changes.
It seems to be like a "super stall" except you are in a fast dive and the elevator is ineffective?
My impression is that "super stall" is just a regular stall, but the plane does not have enough control to get out of it by just pressing forward on the stick and/or trimming. So the plane has to be shimmied side to side to rock out of the stall. Or I suppose it could fall out of it sideways, like a stunt plane, if there were enough altitude and if the plane has enough vertical rudder/yaw control to regain control without just spinning the wrong way around. So IOW, nothing like the 737 crashes. Although the aerodynamic issues of the MAX might mean it is a plane that also stalls in a super way.
-
GoJ, it sounds like you are beginning to entertain the possibility the pilots did not screw up?
No... :-)
(https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Tail_of_a_conventional_aircraft.svg/500px-Tail_of_a_conventional_aircraft.svg.png)
They could not put it nose up by pulling on the yoke because past certain stabilizer angle the elevator doesn't respond anymore. But I still think they should have trimmed back to normal stabilizer angle and then flip the cutout switch. I'm sure a Sully would have done that instinctively, in a sec, immediately, without hesitation, at the first sign of a runaway trim event.
(and of course keep an eye on the speed which they did not)
-
They could not put it nose up by pulling on the yoke because past certain stabilizer angle the elevator doesn't respond anymore.
This post is a hypothesis. We don't know for sure that it is correct. But if we assume it is right, the stabilizer angle is incidental. What this means is that beyond a certain speed, the maximum deflection of the elevator is no longer possible to achieve. So if the stabilizer is angled down to the max, you would need to use near maximum elevator to overcome it and beyond a certain speed this would not be possible.
If the forces are so high that the hydraulics can't move the elevator all the way up... and we're just hypothesizing at this point... is it not unreasonable to think that the forces are also so high that the stabilizer cannot be untrimmed? Hydraulic pump and mechanical advantage vs motor and step down pulley/gearing. Tomato tomato. There's some limit in this whole setup, and the first part that fails should not be the stabilizer mechanism breaking, leaving the stabilizer and elevators flapping in the wind.
Speed factor: we do not now what speed at which this occurs, exactly. It has been stated as a fact that at "low speeds" the plane can be flown with full nose down stabilizer. What about "regular speeds?" The extreme overspeed of the plane at the very end is the result of the pilots increasingly losing battle, perhaps, of keeping the nose up, and at the very end the plane is way nose down. That extreme end reading is not very meaningful. And cutting throttle does not immediately help this situation. It initially makes it worse. Despite the altitude of 14K feet, the plane never got above 7-8K feet AGL, and this is not even considering any nearby mountains/obstacles. This is a fairly low altitude should anything go wrong. A stall is possibly not even recoverable from here unless you are carrying some extra speed. Altitude and speed are like money in the bank to a pilot. I posit that it may be extremely counter-intuitive for a pilot to cut throttle when struggling to keep a plane in the air.
-
They could not put it nose up by pulling on the yoke because past certain stabilizer angle the elevator doesn't respond anymore.
This post is a hypothesis. [...]
No, it's not. The angle of the elevator is relative to the angle of the stabilizer, past a certain (excessive) stabilizer angle, the elevator can only vary the rate of nose dive but can't revert the situation to a nose up.
-
No, it's not. The angle of the elevator is relative to the angle of the stabilizer, past a certain (excessive) stabilizer angle, the elevator can only vary the rate of nose dive but can't revert the situation to a nose up.
Ok, you might be missing the entire point of that pilot's post.
The point is that the elevator at full up CAN overcome the stabilizer. This has been demonstrated on at least a 737 simulator at low speeds. But at high enough speed, the pilot has theorized that the 737 may experience blowback or blowout or w/e he calls it.... where the elevator CANNOT actually sustain this full up position, because the wind load overpowers the hydraulics. The initial response might be near 100%, but then the elevator wilts like old lettuce under the load.
Imagine either the hydraulic pressure isn't enough to get the stabilizer up and/or after it's full up, the force is so high that the hydraulic pump is not fast enough to maintain the peak pressure (against normal/expected leakage) with the actuators being fully opened and exposed to this high of a sustained load ... and the elevator wilts back towards neutral. And now the plane is totally fucko'd. This explains why the downwards angle is so severe at the end of each crash. I theorized the pilots might have at the last decided to try the roller coaster maneuver. But it is also possible they actually progressively lost elevator control in the upwards direction as the hydraulics were gradually overpowered and/or leaked/failed. Unlike in Alaskan Air 261, where the pilots could have sustained level flight indefinitely by pulling on the yoke with 130 lbs of force (if the entire linkage hadn't eventually snapped), if this pilot's theory is correct the pilots would have pulled back on the yoke with 130 lbs, but to no avail. After initially leveling the plane, the nose would progressively drop... faster and faster... despite their continued effort at the yoke/elevator.
According to this pilot, this was scarier than a stall. No, this is scarier than a "super stall."
-
If the forces are so high that the hydraulics can't move the elevator all the way up... and we're just hypothesizing at this point...
It is not about ability of hydraulics. At high speeds angle of attack of stabilizer which have bigger surface area will dominate over (whatever you do with) elevator.
-
^Then why doesn't the stabilizer, with its larger surface area, dominate at lower speeds, too? The stabilizer is larger, but the total angle of the stabilizer is limited to about 4.6 degrees. The elevator is presumably capable of moving more than 4.6 degrees, allowing it to overcome the stabilizer... if the elevator can actually achieve/sustain its max up position. Many pilots have stated as a fact that the 737 MAX can actually be flown with full stabilizer down... at "low speed."
I thought maybe that the aerodynamics changed at higher speed, but this pilot's "blowout" experience on another plane puts more food for thought on the table.
-
^Then why doesn't the stabilizer, with its larger surface area, dominate at lower speeds, too?
Mentour Pilot said in his video that at high speeds stabilizer dominates, thou he did not comment about low speeds. BTW there is other factor at *high* speeds - transsonic airflow.
-
True, all that. I bet the plane was out of control/lost well before transsonic speed was reached, though. It only scratched at this speed at impact. And GoJ and I were discussing this new theory that he posted about another pilot's experience/theory regarding
"blowout." "blowback."
Blowback is deadly.
Blowback means the elevator is gradually blown back to lower and lower elevation angles by the pressure of the air as the speed increases. The hydraulic actuators can’t overcome the force of the air and gradually back down if the force of the air grows too strong.
If a blowback phenomenon is confirmed for the 737 at the speeds and altitudes flown, this is what happened at the end of the JT610 flight and probably ET302.
The only remedy to the blowback induced dive would have been a full nose up trim application, for a long time (throttles to idle and air brake would also have helped). But the reaction to trim is slow and the aircraft was now heading for earth. The reflex is not to trim but to pull for all there is, by both pilots, you have seconds to stop the dive. It didn’t help.
It's just a theory. If it can happen, though, I'd like to see the 737 training that covers this ^.
-
[...] The stabilizer is larger, but the total angle of the stabilizer is limited to about 4.6 degrees. The elevator is presumably capable of moving more than 4.6 degrees, allowing it to overcome the stabilizer... if the elevator can actually achieve/sustain its max up position. Many pilots have stated as a fact that the 737 MAX can actually be flown with full stabilizer down... at "low speed."
I thought maybe that the aerodynamics changed at higher speed, but this pilot's "blowout" experience on another plane puts more food for thought on the table.
From Bjorn's ("blowback") blog post:
I know from pilots who have tested to fly a 737 in the simulator that you can keep the nose up with the Pilot controlled elevator, even against a full nose down trimmed horizontal stabilizer
From http://www.b737.org.uk/mcas.htm (http://www.b737.org.uk/mcas.htm) :
There are three significant changes to MCAS software being worked on by Boeing:
To give the system input from both angle-of-attack sensors, Currently MCAS only uses data from the angle of attack sensor on the side of the active FCC, (see AoA source). The system will have split vane monitor and Mid Value Select (MVS) input. This will both enhance detection of erroneous AoA vane behaviour and the MVS signal selection will pick the average of ADIRU L & R and the previous MVS output. If the output of the two AoA vanes differ by more than 5.5 degrees MCAS will be disabled.
To limit how much MCAS can move the horizontal stab to guarantee sufficient handling capability using elevator alone. In its original report, Boeing said that MCAS could move the horizontal stabilizer a maximum of 0.6 degrees. However, after the Lion Air crash, it told airlines that MCAS could actually move it 2.5 degrees, or half the physical maximum. Boeing reportedly increased the limit because flight tests showed that a more powerful movement was needed at high AoA rather than at high Mach.
A modification to the activation and resynchronisation schedule. MCAS will be limited to operate only for one cycle per high AoA event, rather than multiple. At present it will operate for 10s, pause for 5s and repeat for as often as it senses the high AoA condition is present. Furthermore the logic for MCAS to command a nose up stab trim to return to trim following pilot eletric trim intervention or exceeding the forward column cutout switch, will also now be improved.
Sounds somewhat contradictory to me... which one's right?
-
BTW this is interesting, a 737 NG "users manual":
https://www.737ng.co.uk/B_NG-Flight_Controls.pdf (https://www.737ng.co.uk/B_NG-Flight_Controls.pdf)
I can't find the one for the MAX 8/9. It seems that with the flaps extended the electric trim button on the yoke would have trimmed twice as fast.
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=708495;image)
-
BTW this is interesting, a 737 NG "users manual":
https://www.737ng.co.uk/B_NG-Flight_Controls.pdf (https://www.737ng.co.uk/B_NG-Flight_Controls.pdf)
I can't find the one for the MAX 8/9. It seems that with the flaps extended the electric trim button on the yoke would have trimmed twice as fast.
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=708495;image)
When flaps are in use MCAS is disabled, this was stated somewhere above -double win. Now as for how good idea to use flaps at high speeds is an other question...
-
A good article in IEEE spectrum (hopefully not posted previously?!)
https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-737-max-disaster-looks-to-a-software-developer (https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-737-max-disaster-looks-to-a-software-developer)
-
A good article in IEEE spectrum (hopefully not posted previously?!)
https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-737-max-disaster-looks-to-a-software-developer (https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-737-max-disaster-looks-to-a-software-developer)
I’m bothered by the author’s apparent ignorance of the MAX’s design. He implies it’s gone full-on fly-by-wire, which is simply not true. (Wiki says just one control surface is now fly-by-wire.) He appeals to tradition about the benefits of traditional mechanical linkage, despite the fact that this is in fact how the MAX is implemented. He also doesn’t seem to know that the nose gear was indeed raised.
This makes me question his credibility overall, with regards to the hardware side of things. I don’t think he’s as knowledgeable as he wants to appear.
-
I find it a poor article, no mention of functional safety requirements nor S/W testing and application engineering.
His creds are questionable "software executive" "software developer" sounds self-proclaimed. He's got a 1979 Cessna. The story has ADHD, it's all over the place. Yuck.
-
Yes, Tooki. This part was a surprise to read. I don't know what to think about this:
When the flight computer trims the airplane to descend, because the MCAS system thinks it’s about to stall, a set of motors and jacks push the pilot’s control columns forward. It turns out that the flight management computer can put a lot of force into that column—indeed, so much force that a human pilot can quickly become exhausted trying to pull the column back, trying to tell the computer that this really, really should not be happening.
Indeed, not letting the pilot regain control by pulling back on the column was an explicit design decision. Because if the pilots could pull up the nose when MCAS said it should go down, why have MCAS at all?
It read the entire thing, but I must have missed the part about the nose gear.
This part was kind of "rewarding" to me, because I've speculated this, myself. But to hear it stated so unequivocally makes me wonder how he knows this is a fact that only fighter jets are dynamically unstable, at all. I imagined there would be degrees to this that could be detectable/demonstrable but still considered safe enough.
Pitch changes with increasing angle of attack, however, are quite another thing. An airplane approaching an aerodynamic stall cannot, under any circumstances, have a tendency to go further into the stall. This is called “dynamic instability,” and the only airplanes that exhibit that characteristic—fighter jets—are also fitted with ejection seats.
no mention of functional safety requirements nor S/W testing and application engineering.
Yeah, I expected something about that from his 40 years of being a software developer. There was no real insight, here, and indeed, he doesn't even demonstrate any software fault of the plane. Design choices, management shortcuts, lack of oversight... not software faults. It is a bit simplified where he suggests that software developers are lazy because they can push patches. Software requires patches for the same reasons he is explaining that failures should be considered a natural part of complex systems. Software can get really complicated, and no human can fully understand all the ramifications of even a moderately complex piece of software. They can understand this bit or that bit. But then there are hundreds of bits all working together, and things just get complicated. He also seems to blame the software developers for doing something well beyond their scope, lol. If Boeing lets a software company fix their plane without specifying the way in which it should be done, and then they don't even check that it meets normal safety criteria, then who is making the mistake?
In absence of any real data, mind you, I would assume that the software engineers made MCAS do exactly what Boeing employees specified, and how they specified it. They might even have made several suggestions for improvements and/or expressed safety concerns that fell on deaf ears, and they just deferred to the experts (and the customer). Even if the software guys were out of their league... if someone hands you a check and asks you to do something you have no experience or expertise in and says, "just figure something out," with no specific parameters, I'd cash the check and figure something out, and I'd detail what exactly the software does. I'd assume it's up to the customer to determine if it is suitable for his purposes or not. Unless my company includes 737 test pilots and I'm given a fleet of test planes and a really big check to cover accidental deaths and insurance for 100 million dollar planes, I'm not really the end judge of these things.
Overall it reads like one of them 60 Minutes old-dude-rants about the good old days. He is obviously painting a narrative. But it was an easy read and included some valid points and insights from a pilot.
-
Given the shaky factual foundation upon which it’s written, I don’t think any of his “insights” can be given the benefit of the doubt, as far as validity...
-
His experience in recertifying his plane after installing an autopilot is interesting. I noticed he had to do a lot of paperwork, mostly. He didn't mention how much this cost. And it came with an extensive manual, but I don't see where he had to take some sort of test. Also, when his friends fly the plane, the only thing they apparently have to do is take a lesson from the owner of the plane and to demonstrate they understand what they need to.
Also in this rant, he has been suggested that if they had disclosed MCAS from the start, the problem would have come from.... the 737 pilots, themselves. Earlier in the history of the 737, I have read that the plane was initially not popular with domestic airlines because pilots and their unions demanded that the plane have a crew of 3 pilots. In other countries, they flew with 2. And this eventually happened in the US after the union capitulated.
It's ironic that, perhaps, the very persons who could use the information is the person you have to hide it from, for cost reasons.
So all these airline pilots who are saying, "easy, peezy. You just flip the switches, tada, and no problem" is one thing. But the problem as far as the airlines/Boeing was concerned might have been that the pilots union refuses their pilots to fly this new plane until they are promised X hours of training/certification per pilot (at $X per hour). So this is what happens when politics mixes with safety? The pilots union is perhaps in some way indirectly responsible for the political situation that led to this. >:D
I know from people in the industry stories of mechanics basically not doing their jobs unless incentivized with lucrative overtime hours. But in an orchestrated and overt/open gaming of the system, let's say... like government workers at a feeding trough full of borrowed money with not enough oversight. And airlines going into bankruptcy from this Lord of the Flies atmosphere where the management lost control.
-
Given the shaky factual foundation upon which it’s written, I don’t think any of his “insights” can be given the benefit of the doubt, as far as validity...
Hmmm. Think actually you are quite wrong. There is nitpicky stuff which I completely agree with that the article fails (probably) to get right. I think the bigger lesson is correct, its about how to manage and *not* manage life critical projects.
There is a basic engineering truth here--namely the iron triangle.
http://kevinharrisarchitect.com/iron-triangle/ (http://kevinharrisarchitect.com/iron-triangle/)
(Stuck in a better link here after original posting).
I was taught this early in my career and have found it to be mostly true. Boeing picked fast (fixed deadlines) and cheap (totally cost constrained) that means good *had* to suffer. The devil is in the details, the writing was on the wall, etc. etc. As soon as I read in the Seattle times that the two things were paramount--fast&cheap-- the broad strokes of the rest becomes obvious. Boeing management probably picked up some hefty bonuses for managing those d*mn engineers so well. But 347 people died as a result. So, yes, heads need to roll.
-
Safety critical software updates do not get released as a "patch" :palm:
There is a formal engineering change order, FMEA assessment, coding, peer review, testing, validation, verification and regulatory assessment. The S/W update goes through an entire approval process. The quality management system (i.e. ISO 9001) is also involved. A lot of meetings, paperwork and hoops before anything gets released to end users. There is full traceability with the paper trail.
It easily adds x10 factor for development time compared to basic embedded system software. Many months are needed to properly do a S/W change or add a module.
The need for MCAS might have come very late in the project - during test flights where the aircraft's handling issues arose. This would make it a last minute panic, rush to implement and deploy something.
Keeping MCAS specifications "over-simplified" would be one way to add it quickly and not delay the project.
It's still shocking how Boeing and Collins bungled this software or covered up it's critical nature in order to also skirt giving pilots additional training.
Canada is demanding "pilots should experience the fixes Boeing is devising in simulators" instead of an iPad session, which is against what the FAA is saying.
-
Earlier in the history of the 737, I have read that the plane was initially not popular with domestic airlines because pilots and their unions demanded that the plane have a crew of 3 pilots. In other countries, they flew with 2. And this eventually happened in the US after the union capitulated.
It was never a Boeing or FAA requirement, it was about United Airlines union contracts requiring 3-man crews in larger aircraft back in the 1960's, since they were the only US airline flying the 737 in significant numbers at the time. Also, that third man wasn't a pilot, he was a flight engineer. In the 737 he was a glorified secretary. He had a seat with no console and nothing to do other than simple stuff like routine radio traffic and paperwork. It wasn't until about 1972 that UAL got rid of that 3rd man in the cockpit. In commercial aviation, the flight engineer is a near-dead position these days, since most older aircraft that needed them are no longer in service.
So even though you chose to mention it in the same paragraph as MCAS, I rather doubt the the fact there's only been a 2-man crew in the 737 for the last 47 years is relevant in any way. But don't let me stop a good conspiracy theory!
-
Earlier in the history of the 737, I have read that the plane was initially not popular with domestic airlines because pilots and their unions demanded that the plane have a crew of 3 pilots. In other countries, they flew with 2. And this eventually happened in the US after the union capitulated.
It was never a Boeing or FAA requirement, it was about United Airlines union contracts requiring 3-man crews in larger aircraft back in the 1960's, since they were the only US airline flying the 737 in significant numbers at the time. Also, that third man wasn't a pilot, he was a flight engineer. In the 737 he was a glorified secretary. He had a seat with no console and nothing to do other than simple stuff like routine radio traffic and paperwork. It wasn't until about 1972 that UAL got rid of that 3rd man in the cockpit. In commercial aviation, the flight engineer is a near-dead position these days, since most older aircraft that needed them are no longer in service.
So even though you chose to mention it in the same paragraph as MCAS, I rather doubt the the fact there's only been a 2-man crew in the 737 for the last 47 years is relevant in any way. But don't let me stop a good conspiracy theory!
Are you sure the 737 was operated with a flight engineer? The only seat available in the flight deck is the jump seat, and when deployed it is blocking the flight deck door. The bulkhead with the circuit breakers is right behind the pilots seats.
It was the Boeing 767 that had been designed with a flight engineer position only because at least one union was pushing for this. Unfortunately for the union, the 767 was designed for a crew of two, and the flight engineer had nothing to do.
:)
-
I rather doubt the the fact there's only been a 2-man crew in the 737 for the last 47 years is relevant in any way. But don't let me stop a good conspiracy theory!
Thanks! Everything else you stated supports the point I made, fantastically. Then there's this nonsensical statement for which I forgive you. >:D
-
https://www.youtube.com/watch?v=aoNOVlxJmow (https://www.youtube.com/watch?v=aoNOVlxJmow)
-
New York Times (https://www.nytimes.com/2019/04/20/business/boeing-dreamliner-production-problems.html): Claims of Shoddy Production Draw Scrutiny to a Second Boeing Jet. Workers at a 787 Dreamliner plant in South Carolina have complained of defective manufacturing, debris left on planes and pressure to not report violations.
At the North Charleston plant, the current and former workers describe a losing battle with debris.
That describes the situation I have in my workroom: " a losing battle with debris".
-
https://www.nytimes.com/2019/03/14/business/automated-planes.html (https://www.nytimes.com/2019/03/14/business/automated-planes.html)
In nearly 100 million flights by United States passenger airlines over the past decade, there has been a single fatality. Other than most landings and takeoffs, the planes have largely been flying themselves.
But the recent crashes of Boeing 737 Max 8 jets in Indonesia and Ethiopia have raised questions about the downside of all that automation.
Pilots now spend more time learning these automated systems than practicing hands-on flying, so newer pilots are less comfortable with taking manual control when the computer steers them wrong, according to interviews with a dozen pilots and pilot instructors at major airlines and aviation universities around the world.
“The automation in the aircraft, whether it’s a Boeing or an Airbus, has lulled us into a sense of security and safety,” said Kevin Hiatt, a former Delta Air Lines pilot who later ran flight safety for JetBlue. Pilots now rely on autopilot so often, “they become a systems operator rather than a stick-and-rudder pilot.”
As a result, he said, “they may not exactly know or recognize quickly enough what is happening to the aircraft, and by the time they figure it out, it may be too late.”
In October, a Lion Air jet crashed in Indonesia, killing 189 people. Investigators now think the pilots struggled to control the Boeing aircraft after its automated systems malfunctioned, in part because they didn’t fully understand how the automation worked. The authorities are investigating what caused Sunday’s crash of the same model jet in Ethiopia, in which 157 people died.
While automation has contributed to the airline industry’s stellar safety record in recent years, it has also been a factor in many of the crashes that have still occurred around the world. A 2011 study by a federal task force found that in about 60 percent of 46 recent accidents, pilots had trouble manually flying the plane or handling the automated controls. Complicated automation systems can also confuse pilots and potentially cause them to take action they shouldn’t, pilots said.
President Trump weighed in on Tuesday, posting on Twitter that airplanes have become too technologically complex and that he wants “great flying professionals that are allowed to easily and quickly take control of a plane!”
https://thepointsguy.com/news/captain-sully-sullenberger-on-737-max-crash/ (https://thepointsguy.com/news/captain-sully-sullenberger-on-737-max-crash/)
We do not yet know what caused the tragic crash of Ethiopian 302 that sadly claimed the lives of all passengers and crew, though there are many similarities between this flight and Lion Air 610, in which the design of the Boeing 737 MAX 8 is a factor. It has been obvious since the Lion Air crash that a redesign of the 737 MAX 8 has been urgently needed, yet has still not been done, and the announced proposed fixes do not go far enough. I feel sure that the Ethiopian crew would have tried to do everything they were able to do to avoid the accident. It has been reported that the first officer on that flight had only 200 hours of flight experience, a small fraction of the minimum in the U.S., and an absurdly low amount for someone in the cockpit of a jet airliner. We do not yet know what challenges the pilots faced or what they were able to do, but everyone who is entrusted with the lives of passengers and crew by being in a pilot seat of an airliner must be armed with the knowledge, skill, experience, and judgment to be able to handle the unexpected and be the absolute master of the aircraft and all its systems, and of the situation. A cockpit crew must be a team of experts, not a captain and an apprentice. In extreme emergencies, when there is not time for discussion or for the captain to direct every action of the first officer, pilots must be able to intuitively know what to do to work together. They must be able to collaborate wordlessly. Someone with only 200 hours would not know how to do that or even to do that. Someone with that low amount of time would have only flown in a closely supervised, sterile training environment, not the challenging and often ambiguous real world of operational flying, would likely never have experienced a serious aircraft malfunction, would have seen only one cycle of the seasons of the year as a pilot, one spring with gusty crosswinds, one summer of thunderstorms. If they had learned to fly in a fair-weather clime, they might not even have flown in a cloud. Airlines have a corporate obligation not to put pilots in that position of great responsibility before they are able to be fully ready. While we don’t know what role, if any, pilot experience played in this most recent tragedy, it should always remain a top priority at every airline. Everyone who flies depends upon it
https://www.boeing.com/commercial/737max/737-max-software-updates.page (https://www.boeing.com/commercial/737max/737-max-software-updates.page)
https://www.youtube.com/watch?v=T2i3-rotFuQ (https://www.youtube.com/watch?v=T2i3-rotFuQ)
-
https://www.nytimes.com/2019/03/14/business/automated-planes.html (https://www.nytimes.com/2019/03/14/business/automated-planes.html)
In nearly 100 million flights by United States passenger airlines over the past decade, there has been a single fatality.
That statistic hasn't changed, since everything the rest of the article talks about were not United States passenger airlines, nor did they happen in the United States. Plus it didn't even mention that the single fatality had nothing to do with crashing or automation. Crappy journalism leading with that at all, since that's not what they wanted to talk about.
-
>> "Investigators now think the pilots struggled to control the Boeing aircraft after its automated systems malfunctioned, in part because they didn’t fully understand how the automation worked."
And the reason they didn't fully understand how the automation worked was because Boeing sold it as something that did not need to be understood and required no extra training. Because, you know, training costs time and money which could get in the way of sales.
So, basically, it is the fault of the pilots ... for trusting Boeing.
-
So, basically, it is the fault of the pilots ... for trusting Boeing.
Boeing :-- and pilots that crash it the minute something fails :-- too.
-
The pilots had no training for that scenario and the reason they had no training for that situation was that Boeing said no training was needed.
Who is responsible for the pilots not having been trained for that situation?
-
A cockpit crew must be a team of experts, not a captain and an apprentice. In extreme emergencies, when there is not time for discussion or for the captain to direct every action of the first officer, pilots must be able to intuitively know what to do to work together. They must be able to collaborate wordlessly. Someone with only 200 hours would not know how to do that or even to do that.
If real pilots are trained the way Mentour Pilot simulations go... boy, I think there's a conflict, here.
Capt: The plane appears to be crashing. Agree?
Copilot: Yes, I concur. Plane appears to be crashing.
Capt: Proceeding to memory items for crashing of plane. Please. Perform memory items for crashing plane.
Copilot: Memory items for crashing plane. Step 1, put head in ass. Permission to put head in ass?
Capt: Yes, please proceed with head in ass.
>:D >:D >:D :-DD >:D >:D >:D
It has been reported that the first officer on that flight had only 200 hours of flight experience, a small fraction of the minimum in the U.S., and an absurdly low amount for someone in the cockpit of a jet airliner... A cockpit crew must be a team of experts, not a captain and an apprentice.
I imagine this is important if the captain is incapacitated. But failing that, I hope a modern plane can be flown with one competent pilot and one "assistant" who can take orders and perform medial tasks as directed. Whose main reason d'etre is for redundancy/backup.
-
The pilots had no training for that scenario and the reason they had no training for that situation was that Boeing said no training was needed.
They should have known perfectly well how to handle that issue since november 6 2018, because "Following last week’s crash of a brand-new Lion Air Boeing 737 MAX 8 in Indonesia, the plane’s manufacturer has issued an emergency Airworthiness Directive, warning all the aircraft’s operators of a potential instrument failure that could force the plane to fly into a steep dive" and the FAA another:
https://duckduckgo.com/?q=737+emergency+directive+trim+runaway
-
They should have known perfectly well how to handle that issue since november 6 2018, because "Following last week’s crash of a brand-new Lion Air Boeing 737 MAX 8 in Indonesia, the plane’s manufacturer has issued an emergency Airworthiness Directive, warning all the aircraft’s operators of a potential instrument failure that could force the plane to fly into a steep dive" and the FAA another:
Yeah, that's why the crash was such a big deal. The pilots WERE aware, but they still lost control of the plane.
I can't remember where I read this. Initially, the "roller coaster maneuver" was described in the operating manual of the 737. It was recommended to lift the nose as much as possible, then push the nose down while moving the trim. And repeating as many times as necessary. But later this was removed. There was still a warning that the stabilizer could potentially get stuck, but this was moved to a supplemental manual. And the description of how to handle this was completely deleted. It is unclear if this is still taught/trained to pilots or if it got relegated into obscurity, since the need never arose... until MCAS.
Then effect of speed was perhaps not obvious, either. The AD appears to cover the cutting out of the power trim after recognizing MCAS activation, but not including what you may have to do afterward.
-
But they did NOT need to do that (roller coaster maneuver), for the umpteenth time: they just had to (un)trim electrically and flip the cutout switch after that. Any Sully would have done that instinctively, immediately, in a sec, end of the problem.
-
So the planes were all grounded, worldwide, for no good reason except that all pilots, worldwide, are incompetent. I think I get it now.
-
GoJ, You still don't know that, though, do you? The prelim that Ethiopian Airlines released does not include the duration of trim inputs from the pilots. Did I miss something?
We have the info for the Jakarta flight recorders. The trim input was too little at the end. I have not seen this for ET302.
Also, why do you assume that the pilots would know that under-correcting a mistrim is a fatal error? In a world where planes fly themselves, the rule is to not do anything wrong. If the plane didn't crash yet, and you made it a bit better, you might think it will still not crash.
If you make it better, and it is better at first... but it can progressively gets worse very quickly in an exponential way... that is something that you might want to know in advance.
Any Sully would have done that instinctively, immediately, in a sec, end of the problem.
Apparently, Sully is no longer allowed to fly planes. Now the capt and copilot must verbally go through a checklist and announce their intentions and ask permissions before flipping switches and pressing buttons. This is at least what they would do if they are not aware of how fast this can go south. They may have thought the worst was over.
Unless you can clone Capt Sully and include one with every plane, that might not be a very good solution.
Just to be clear, and maybe I'm undertanding things incorrectly, the AD stresses MCAS as the issue and that the solution is to cut stab trim and then MANUALLY trim the plane. Furthermore, at a given initial speed, simply pulling up on the yoke is enough to correct the plane. So if you pull on the yoke, and the plane flies how you want it to, you think the emergency is over. You don't have to correct the trim ALL THE WAY, like you are saying would be automatic, 1 second, done by Sully. (ironically, it might take several long seconds with power). You've cut stab trim; let's further say you have disabled autothrottle. The plane is level, because you are pulling on the yoke. You are still in imminent danger... because of a level of MISTRIM of which pilots apparently do not much relevant experience and training... not because of the potential for further MCAS error.
-
So the planes were all grounded, worldwide, for no good reason except that all pilots, worldwide, are incompetent. I think I get it now.
Where in Spain do you come from? Your logic is flawed.
-
So the planes were all grounded, worldwide, for no good reason except that all pilots, worldwide, are incompetent. I think I get it now.
Where in Spain do you come from? Your logic is flawed.
Where in Poland do you come from? Your perception of sarcasm (https://www.merriam-webster.com/dictionary/sarcasm) is flawed.
-
GoJ, You still don't know that, though, do you? The prelim that Ethiopian Airlines released does not include the duration of trim inputs from the pilots. Did I miss something?
If it's true that the (electric) trim button overrides the MCAS trim commands it follows that they just had to keep pushing it longer. The emergency directive quite clearly suggests that too:
Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT.
-
If it's true that the (electric) trim button overrides the MCAS trim commands it follows that they just had to keep pushing it longer.
Yes, it is true that button overrides MCAS. It is clearly visible in the flight recorder data. Did they knew/notice or not - that's the question which is unanswered.
[edit] Illustration attached. Notice slightly shorter one of three MCAS long trims - because aborted by manual input. Those two graphs tells whole story of the tragedy - cause and possible solution as well.
-
Yes, it is true that button overrides MCAS. It is clearly visible in the flight recorder data. Did they knew/notice or not - that's the question which is unanswered.
But the emergency directive says... "Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT" Hadn't they read it?
-
But the emergency directive says... "Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT" Hadn't they read it?
Apparently not. Who knows. Anyway sitting in our armchairs we can only speculate or guess - what did they know and what did they think during those critical moments. Those answers are up-to professional investigators.
-
You really should stop invoking Sully. He's an excellent pilot, but the incident he's famous for didn't involve malfunctioning controls of any kind. What Sully did was handle one of the most-practiced problems in all of aviation (multiple engine failure) and live to tell the tale. If he'd been able to make it to an airport, it wouldn't even be that famous. Ditching in water is also a training scenario, so I'd suggest that most airline pilots would be able to pull that off if they had to.
-
If it's true that the (electric) trim button overrides the MCAS trim commands it follows that they just had to keep pushing it longer. The emergency directive quite clearly suggests that too:
Do you know that the stabilizer was responding to the button press like it should? Maybe they stopped pressing it because something was wrong. You assume only the manual method of trimming the plane can stick.
The ET302 prelim does NOT include the duration of the manual trim input button presses. We have that information for Jarkarta, not for ET302. This is strange. So we don't know how long they pressed the buttons.
At one point, the Capt requests the FO to press the trim up button with him, at the same time. This suggests that the Captain perceived that the trim was not responding the way he expected it to from his trim button. Was he confused by MCAS? Maybe. At this point the yoke/elevator is responding exactly like he expects. It is sufficient to control the plane, so far. And like a good Capt Sully, he relies on what works as expected. And perhaps he is unaware that this is going to be woefully inadequate in the very near future at the rate of acceleration of the plane in this attitude.
Do you know what happens if the pilots overcorrect the trim? Or let's say, do you know how much over-correction can be done without causing a new and dangerous problem? I don't either. There is perhaps a reason to be conservative in making this adjustment. And with the FO pressing the trim and the Capt pulling the yoke, the FO did not have that feedback and was conservative.
After initially running through the checklist, correcting the trim not quite enough, and doing stab trim cutout... The only thing left in the procedure it to manually trim. This did not work. If they knew how to do it (roller coaster maneuver), then they might have been able to perform manual trim rather than breaking protocol and turning stab trim power back on.
If copilot were allowed to touch buttons without a 30 second song and dance of verbal poetry and permissions, maybe he would have flipped stab trim power back off after correcting the plane the second time, without a second thought, like GoJ's perception of "a Sully." Perhaps Capt was tongue twistered out to figure out how to properly state the exact sequence fast enough in real-time and/or didn't even want it recorded on the voice recorder because he knew it was against protocol. And maybe the Captain left trim power on, on purpose, seeing as how he can "simply press the up button" to fix the problem according to GoJ simplified view... (at higher speeds and low enough altitude, this may not be the case).
-
The ET302 prelim does NOT include the duration of the manual trim input button presses. We have that information for Jarkarta, not for ET302. This is strange. So we don't know how long they pressed the buttons.
We *do* have manual trim information for ET302, graphs in page 26 of prelim report. You can estimate button press times quite precisely:
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=714159;image)
-
^Ahh ok, interesting. The most obvious oddity in this part of the recording is that they do not appear to realize when the MCAS re-activation occurs. There is no attempt to interrupt or to immediately correct it.
Perhaps the capt is hearing the clicks and believes that the copilot is making further up correction and/or vice versa? Too many chefs in the kitchen? The Captain's perception and communication that his trim control is not working as expected and the sharing of responsibility over trim control to the FO who has no yoke feedback was perhaps a significant domino in this outcome. Copilots of both crashes may have underestimated the danger of mistrim, as well. Seeing how calm the captain handled it (breaking out the manual even, in the Jakarta case) but not realizing how the increase in speed has affected things and increased the stakes.
I'd like to try corelate the button presses with the resulting trim changes as measured at the elevator, but I can't find the link. Gonna dig back through this thread to find it and try that later.
-
Do not recall - link was in this thread or not. :-\
Here it is: http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+,(ET-AVJ).pdf (http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+,(ET-AVJ).pdf)
-
Do you know what happens if the pilots overcorrect the trim? Or let's say, do you know how much over-correction can be done without causing a new and dangerous problem? I don't either. There is perhaps a reason to be conservative in making this adjustment. And with the FO pressing the trim and the Capt pulling the yoke, the FO did not have that feedback and was conservative.
There's a dial next to the stabilizer trim wheel, if they didn't know the proper takeoff trim range (how the hell can a pilot NOT know that?), it's marked in green so they could have looked at it. Obviously, should have kept pressing nose up until the dial was well into the green... then flip cutout, end of problem.
(https://qph.fs.quoracdn.net/main-qimg-1dc99dbe662c71d7c470cf1bb873a8ff.webp)
BTW, see the flap lever next to the trim wheel? Could also have put that in position 1 to accelerate the (un)trim and disable MCAS.
-
Funny I was just typing a post about this.
In this low altitude with mountainous terrain, perhaps the copilot is incorrectly fixating his view out the windshield rather than on the controls. The view of the controls are very cramped, and I imagine it is disorienting to change view/focus between miles and inches.
In a fighter jet, the navigator has no view out the front of the plane, at all. Perhaps some sort of electrically darkening windshield (yeah, what could go wrong?) would be useful in a commercial plane so that both pilots don't redundantly fixate on the horizon/terrain. Copilot would have nothing better to look at than the controls and instruments. To see which way wheel is turning, where the trim indicator is at, and what the air speed and pitch is. This could perhaps also improve instrument-only flight competence/confidence. Like blinders for a horse. Don't worry about things that the other guy has control over.
Obviously, should have kept pressing nose up until the dial was well into the green... then flip cutout, end of problem.
MP simulation:
https://youtu.be/xixM_cwSLcQ?t=1154
Captain doesn't specify numbers/rotations/duration. Neither pilot ever looks down at the indicator. All very relative and by feel. I think it is possible pilots develop a habit of not looking at the trim indicator or the wheel during flight. It's an awkward location and the wheel turns rather frequently with the autopilot on. It's perhaps something that has been habituated. I.e., totally ignored. Heck, reading the amount of trim isn't even part of the memory items.... the only criteria is if the wheel is moving by itself or not. The only communication relating to absolute trim position in this video is "it's getting quite heavy, now."
-
You really should stop invoking Sully. He's an excellent pilot, but the incident he's famous for didn't involve malfunctioning controls of any kind. What Sully did was handle one of the most-practiced problems in all of aviation (multiple engine failure) and live to tell the tale. If he'd been able to make it to an airport, it wouldn't even be that famous. Ditching in water is also a training scenario, so I'd suggest that most airline pilots would be able to pull that off if they had to.
Thank you! I, too, was tiring of GotJ's constant invoking of Sully as some kind of aviation deity*. Skilled pilot? Yes. Lucky? Lucky as hell.
*Reminds me of how non-tech-historians "discovered" Nikola Tesla a few years ago (thanks, Elon... ::) ) and ascribe to him things that go far beyond his (already significant) legitimate accomplishments. (And yes, I resent the "cool" kids evoking Tesla's good name for hipster points, even though when I was a kid, they bullied me for being a nerd who knew about people like Edison, Watt, Marconi... and Tesla.)
-
It's sad, but you don't have to be a Sully to understand that they royally screwed up. Very very sad. As they say, shit happens.
-
It's sad, but you don't have to be a Sully to understand that they royally screwed up. Very very sad. As they say, shit happens.
I don’t think you realized that the comment above (and the one I quote) are talking about you. Enough with the Sully.
-
I don’t think you realized that the comment above (and the one I quote) are talking about you. Enough with the Sully.
Oh, yes, I do realize, perfectly! And I wonder what makes some people think they can go around telling others to shut up. Tip of the day: If you disagree with someone, that's alright, get over it, life is like that.
Sincerely,
Have a nice day!
-
It's sad, but you don't have to be a Sully to understand that they royally screwed up.
You don't know anything about Sully except he was put in a tough situation and he ended up making a questionable decision. Some people believe he had time to make a better estimate and actually land at an airport.
Sully throws shade at Ethiopian Airlines, suggesting that the copilot's 200 hours was unacceptable in the US. He also suggests that the pilots have to be experienced enough to read each other's minds. In order be able to handle a situation that a single sensor failure can lead to, you need two greatly experienced pilots with ESP? What if one of those pilots had been incapacitated? Personally, i'd rather be on a plane that doesn't do this. Give me two average professional pilots and a debugged plane, and you can have Capt Sully and his ESP flying partner personally flying you around on a plane that has been grounded. Maybe Goose is available.
GoJ, most everyone following this thread understands that the pilots probably could have saved the plane if they had reacted differently. Let's even say that this is the most likely scenario. No one needs Capt Obvious to paint this narrative, so we owe you a thanks for repeatedly doing it, anyway. It's god's work, my friend. Keep it up.
I have made a lot of reaching speculations. At least some, if not all, of which will prove to be wildly wrong. I'm not trying to paint a narrative as if I know what happened. It's possible we find out more in the next 9 months. I can still imagine scenarios where Boeing is morally vindicated (but the damage has already been done).
-
It's sad, but you don't have to be a Sully to understand that they royally screwed up.
You don't know anything about Sully except he was put in a tough situation and he ended up making a questionable decision. Some people believe he had time to make a better estimate and actually land at an airport.
afaiu it was shown in the simulator that he could made it the airport and landed, but only just, so it required he instantly take the decision and getting it wrong could results in a crash in a populated area
-
It's sad, but you don't have to be a Sully to understand that they royally screwed up.
You don't know anything about Sully except he was put in a tough situation and he ended up making a questionable decision. Some people believe he had time to make a better estimate and actually land at an airport.
afaiu it was shown in the simulator that he could made it the airport and landed, but only just, so it required he instantly take the decision and getting it wrong could results in a crash in a populated area
This ^^^^
So much could have gone wrong so the safest plan was the Hudson.
-
^ And he would have had only one chance at it. Come in too steep, and you have to make the best of it. At least the Hudson was the longest landing strip in the area. I don't think he made a bad decision, but it was not like the alternative was only better because of the cost of the plane and evacuation.
He also wasn't sure that everyone would make it off the plane. There could be people with disabilities. There could have been some panic in the egress. There could have been damage to the plane in the landing. He could have bugsplatted a couple crazy college kids in a canoe.
He knew he could land the plane in one piece on the Hudson. And he knew that perhaps a majority of the passengers could egress before the plane sank or caught fire, including himself if it came to it.
I think he made the right call, but there was nothing heroic about it. A pilot concerned only for his own life would have done the same thing. Usually, this decision is always going to be the same. This is why we don't give the pilot an ejection seat. No one should ever have to make that kind of choice. But notice in this case, the cabin is pretty damn close to an exit. I would also bet Capt Sully knows how to swim.
-
But notice in this case, the cabin is pretty damn close to an exit. I would also bet Capt Sully knows how to swim.
Now you're actually being rude in trying to turn historical fact into unfounded speculation. Sully was one of the last people to leave the plane after the water landing. He even checked the plane himself to make sure everyone was out. Plenty of witnesses. You should know this unless you were completely brain-dead to the news ten years ago.
But since you're measuring distance from the exit: there are actually TWO window exits in the cockpit that are intended for emergency egress, one for each pilot. There are even ropes so they don't have to jump.
-
Of course if the plane isn't in immediate danger, the captain will heroically be the last person to leave. Of course, he has every intention of being the last guy off the plane, even while it is sinking. Even if everybody was not going to make it. But that didn't happen. He didn't get to find out what he would have done. Intentions != actions, and I don't think you can accurately predict what anyone will do when that push comes to shove. Capt Sully had that option. He gets to stand right next to the exit, breathing freedom, whilst heroically intending to be the last guy off the plane. If the plane isn't sinking, do you think it takes a hero to do that? The guy tucked in the back of the plane away from an exit and waiting for the line of people in front of him to move... for that old lady to frikkin jump, already, and start swimming... he didn't have that option. If he did, he would trade places in a hearbeart, and he would stand there next to the exit, being a hero, too. At least right up until the last second where not everyone makes it. Then we don't know what he will do anymore than Capt Sully.
Capt Sully didn't do anything wrong. He performed under pressure, he executed, he kept control. Good and good and good. But he never had to really make a heroic decision. I bet Sully would be the first person to say it. He is just a pilot who did his job. The airline wants him to be a hero, because it's good for their reputation and lawsuits.
The helicopter tour pilot made it out alive after a perfectly executed water landing. Nothing wrong with that. If he couldn't save his passengers, why should he die?
-
They had to react quickly, that's why experience counts, they had not much time to guess the proper sequence of actions. Here in a forum we have all the time in the world...
-
"Guessing"? Just what exactly do you think pilots do in their pilot training?? It's all about practicing how to deal with the unexpected, so that when it happens, they already know what to do and how to do it, because they've practiced it a bunch of times.
-
And that's exactly why I said guess
-
Sully has said as much himself, he did his job, he's a highly competent and experienced pilot who remained calm during an emergency and did what he was trained to do. There was also a significant amount of luck involved, he had enough speed and altitude to get to a suitably open space to put it down, had he been elsewhere things would not have turned out as well. His performance was admirable but I don't think I'd go so far as to call him a hero. He did exactly what any competent pilot would try to do, and he pulled it off almost perfectly.
-
And that's exactly why I said guess
So, then, you really have no idea what pilots do...
-
They had to react quickly, that's why experience counts, they had not much time to guess the proper sequence of actions. Here in a forum we have all the time in the world...
And that's exactly why I said guess
Ok, going back to ET302:
The only way a pilot would have significant experience with solving this problem is if they had been so incompetent to begin with that they had screwed up the trim way out of whack.* They would have gotten this experience by allowing a plane to become dangerously close to losing control... probably with a load of passengers on board. This grossly out of trim problem is so rare, they moved the diagnosis to a supplemental reference and deleted the solution, entirely, some decades ago. I suppose they figured anyone who would need the deleted info should really just not fly planes. Since the pilot is now experiencing it for the first time, with an intermittent runaway trim on top, and they don't have "all the time in the world" the way you do, do you think it's at least possible that Capt Sully and his experienced copilot could also have botched it?
*It's not like the pilots have many/any opportunities to intentionally pull stunts with their employers' 737's, even on the rare occasion they are flying a near empty plane with just a few other crew.
Also, the reason they undercorrected is perhaps not so strange. Every pilot is fully aware of the dangers of overcorrecting in this scenario. Some pilots are apparently unaware, at this point in time, of any significant danger of undercorrecting, thinking they can just eventually get the trim into adjustment in stages, without being aware of the other parameters which must be considered. Hopefully this is no longer the case.
I don't see any obvious reason Sully would have known any better. He was an experienced commercial passenger pilot, not a stunt pilot. This is like thinking an experienced bus driver will know what to do when the bus goes into a slide. We pick bus drivers that don't slide the bus in the first place. This trim problem is so far out of the regular "lines" it doesn't normally exist. And if we only let experienced Indy car racers drive buses, I don't think it would make travelling by bus any safer. Personality type and temperament might increase the accident rate.
GoJ: we've been around and around, so I will also say this:
The memory item says nothing about looking at the trim indicator and putting it back to green band by using the trim button before powering it off. It says the button CAN be used to correct trim before stab cutout. That makes it sound like it's optional. And that the "correct" amount of trim is just a judgement call which is not necessarily of vital importance but more for convenience of the pilot. Maybe the pilot has some other additional training/education that covers this stuff in more detail, and perhaps that additional education and training should have been adequate. But the emergency procedure should perhaps better cover the actual emergency and not just the malfunction that can lead to this emergency in the first place. Going back to Jakarta, the captain did not appear to realize how close he was to losing control of the plane. Like you, he thought, well, just press the up button. Give control to the copilot and start reading a manual.
-
To my mind, any pilot that gets everyone back down on the ground alive after a major in-flight disaster is a hero - whether they did it by the book, or by being creative.
It is far too easy to second-guess decisions after the fact... even if the decisions seem simple, anyone who has ever been in a real life or death emergency knows how hard it is to think straight under those circumstances. We all like to think that it would be no problem for us - just like more than half of drivers think they are above average...
-
Sully has said as much himself, he did his job, he's a highly competent and experienced pilot who remained calm during an emergency and did what he was trained to do. There was also a significant amount of luck involved, he had enough speed and altitude to get to a suitably open space to put it down, had he been elsewhere things would not have turned out as well. His performance was admirable but I don't think I'd go so far as to call him a hero. He did exactly what any competent pilot would try to do, and he pulled it off almost perfectly.
A significant amount of luck involved... Yes.
That was a dual engine flame out at 3000 ft, in initial climb.
The meteorological conditions were day VFR. In night VFR conditions it would have been much more difficult to locate a suitable landing area. In IFR conditions, it would have been impossible for the crew to locate a suitable landing area.
The elapsed time between dual engine flame out at 3000 ft, and touch down was probably three minutes, maybe less.
GeorgeOfTheJungle is right, the crew had no time to guess anything; they barely had time to react.
Also, I am not aware of any airline crew training for a dual engine flame out at 3000 ft, in initial climb. The fact that North American pilots typically grind their teeth in General Aviation for several thousand of hours before joining an airline make all the difference in the world.
:)
-
Geschäftsführer Boing Adolf Muilenburg runs some marketing blubber and not answer questions properly! MCAS does not need any pilot training he says. That was new one!
https://www.youtube.com/watch?v=r0MIPMbRFDM (https://www.youtube.com/watch?v=r0MIPMbRFDM)
Former Boing employees now Blowerwistles says AOA damaged during assembly!
https://www.youtube.com/watch?v=Ba5eJGNuoCc (https://www.youtube.com/watch?v=Ba5eJGNuoCc)
-
https://www.youtube.com/watch?v=NhZ0D-JRtz0 (https://www.youtube.com/watch?v=NhZ0D-JRtz0)
-
You really should stop invoking Sully. He's an excellent pilot, but the incident he's famous for didn't involve malfunctioning controls of any kind. What Sully did was handle one of the most-practiced problems in all of aviation (multiple engine failure) and live to tell the tale. If he'd been able to make it to an airport, it wouldn't even be that famous. Ditching in water is also a training scenario, so I'd suggest that most airline pilots would be able to pull that off if they had to.
And even he (and the rest of the crew) didn't get it all right - they didn't operate the “ditching switch” which closes all the apertures which would allow water to flood the plane. Not that it was his fault, the crew didn't have enough time to reach that item which was well down the checklist, though no doubt someone will claim he should have known about that switch.
If the situation was slightly different, with rescue boats being further away, things could have turned out much worse because of that missing step.
-
You really should stop invoking Sully.
I agree. It's just silly. There is plenty of evidence by now that Boeing is very gravely at fault. Maybe a different pilot or a stroke of luck could have saved some people but that does not change the fact that the accidents were caused by Boeing.
-
https://www.youtube.com/watch?v=KB4lCbT5oX8 (https://www.youtube.com/watch?v=KB4lCbT5oX8)
-
https://www.youtube.com/watch?v=NDbf6G8V4YQ (https://www.youtube.com/watch?v=NDbf6G8V4YQ)
-
More Boing MCAS crap seeping out (WARNING!! its from CNN but anyway).
https://www.youtube.com/watch?v=VkO_NL3t4lI (https://www.youtube.com/watch?v=VkO_NL3t4lI)
-
I agree. It's just silly. There is plenty of evidence by now that Boeing is very gravely at fault. Maybe a different pilot or a stroke of luck could have saved some people but that does not change the fact that the accidents were caused by Boeing.
Machines fail. The pilots are there among other things to take over when something fails. But they have to know what to do... and do it quickly enough.
The Boeing 737 MAX 8 Crashes: The Case for Pilot Error
https://www.linkedin.com/pulse/boeing-737-max-8-crashes-case-pilot-error-vaughn-cordle-cfa (https://www.linkedin.com/pulse/boeing-737-max-8-crashes-case-pilot-error-vaughn-cordle-cfa)
A Detailed Review of the Ethiopian And Indonesian Preliminary Accident Reports
By Vaughn Cordle, CFA and Don McGregor, USAF Maj Gen (Ret)
April 8, 2019
In our previous article, “Boeing’s Grounding: Catastrophic Crashes, and Questions about Boeing’s Liability and 737 MAX Aircraft Viability,” we wrote about the many issues surrounding the recent 737 MAX 8 crashes and connected disparate elements into a preliminary review. One of our early observations was that “pilot error” was the largest contributing factor in both accidents—not the only one but the most consequential factor. The second largest contributing factor for the Lion Air accident was Boeing’s failure to disseminate critical MCAS characteristics to both the FAA (especially during the safety analysis required for certification) and all regulatory bodies and MAX series aircraft operators worldwide.
Since the release of the Ethiopian Aircraft Accident Investigation Preliminary Report, numerous articles and analyses have surfaced that appear to put the blame on the manufacturer. We do not dispute Boeing’s possible culpability but feel it is important that the major contributing factors are put into proper context and weighed appropriately.
Culpability is the central issue of the manufacturer-versus-pilot-error controversy and our new analysis of the crashes and the accident reports point to pilot error being the most important contributing factor.
Before we begin, we will present our analysis of Ethiopian Airlines (ET) Flight 302 since it is the most recent report and has produced some unfortunate controversy. We will follow with a review of the Lion Air accident, the plethora of MCAS information and lessons learned, which, had they been known, should have prevented the Ethiopian crash.
Pilot Errors in Ethiopian Airlines Flight 302
There are two critical and fatal pilot errors that were not properly identified and discussed in the Ethiopian preliminary report’s Initial Findings and Safety Recommendations. The report falls short in terms of properly identifying or prioritizing the primary causes and their relationship to the ultimate effect—the crash. We believe that our analysis of the report’s findings and “ET302 Preliminary FDR [Flight Data Recorder] (DFDR) Data” provides strong evidence that supports our view.
We divide our analysis of why ET 302 crashed into essential and critical arguments that identify the two fatal pilot errors.
Critical Arguments
1. The pilots (crew) mismanaged engine thrust and airspeed
2. Excessive airspeed rendered manual trim ineffective
3. The crew deviated from the emergency procedure
4. Crew experience and competency a major contributing factor
Pilot Errors
1. Mismanagement of engine thrust and airspeed
2. Deviation from company and Boeing procedures
We realize that simplification of a complicated accident is difficult but after a careful analysis of the Ethiopian Accident Investigation Bureau report, we are confident that our original conclusion is correct. The Ethiopian accident report findings and safety recommendations lack context and insight to adequately explain why the aircraft crashed, resulting in the loss of eight crew and 149 passengers on board. We provide that context and additional insight.
Why ET Flight 302 Crashed
The Ethiopian preliminary report confirms, in the appendixes, that Boeing and the FAA issued bulletin recommendations and directives dealing with the potential MCAS problem and how to diagnose and properly handle potential faulty AOA sensor issues. Ethiopian airlines received Boeing’s Flight Crew Operations Manual Bulletin number TBC-19 dated November 6, 2018—116 days before Flight 302 crashed.
After takeoff, the AOA’s faulty inputs showed up in various [left side] flight indicators
Shortly after takeoff, there were several indications and warnings presented to the pilots, much like Lion Air Flight 43 and the fateful Lion Air Flight 610 some months earlier. In fact, according to the report, “shortly after liftoff, the left and right recorded AOA values deviated. Left AOA decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the left AOA value reached 74.5° in ¾ seconds while the right AOA reached a maximum value of 15.3°.” In addition, the reports states, “the airspeed, altitude and flight director pitch bar values from the left side noted deviating from the corresponding right side values”—a variance that should have displayed an ALT DISAGREE alert.
The problems compound
According to the report, “At this time, the left stick shaker activated and remained active until near the end of the recording.” Also, adding to their problems, the master caution warning along with an ANTI-ICE light came on alerting them to an anti-ice system problem. Toward the end of the flight, another master caution illuminated, this one was associated with an L ALPHA VANE light. This indicated that there was an AOA vane heat failure—the AOA vanes are heated (on after engine start) and are part of the PROBE HEAT system.
Why this is important
The warnings and alert indications highlight the immediate problems the pilots experienced—but also highlights Boeing’s bulletin, issued to Ethiopian Airlines on November 6th, describing that these types of indications (i.e., problems) were the result of “erroneous AOA inputs” and their relationship to an impending runaway trim.
An erroneous AOA can cause some or all the following indications and effects:
· Continuous or intermittent stick shaker on the affected side only
· Minimum speed bar (red and black) on the affected side only
· Increasing nose down control forces
· Inability to engage the autopilot
· Automatic disengagement of the autopilot
· IAS DISAGREE alert
· ALT DISAGREE alert
· AOA DISAGREE alert
· FEEL DIFF PRESS light
However, to have that many aircraft warnings and indicators going off is highly unusual and when presented during a critical phase of flight, like takeoff or during climb, can create a very stressful and time-compressed situation. It is during these situations that pilots make the most mistakes and why we rely heavily on our training and following—standard operating procedures (SOPs)—emergency procedures. It should be noted the entire flight lasted only 6 minutes and 45 seconds before the plane slammed into the ground killing all aboard.
Let’s begin with four critical arguments
1) Pilots mismanaged engine thrust and then allowed airspeed to exceed certified aircraft speed limit (critical error #1)
After takeoff, the left and right recorded AOA values deviated and the left stick shaker activated (remained active until the end of the recording). At 400 feet above the ground (AGL), the captain called for the co-pilot to engage the autopilot and an autopilot warning is recorded.
At 1000 feet AGL, the left autopilot was engaged but disengaged 33 seconds later. Erroneous AOA signals can cause automatic disengagement of the autopilot. The pilots retracted the flaps and selected “Level-Change” mode, which controls the aircraft’s pitch and also, via the autothrottles, the engine thrust (power and speed). In this case, the thrust was set to 94% (N1 Reference), a normal high-power setting for climb-out. At the same time, and a requirement for Level-Change mode, the pilots manually put 238 knots airspeed in the airspeed window.
The first indication of a problem
Once the flaps retracted and the autopilot disengaged, faulty AOA signals to MCAS drove the stabilizer nose-down (AND), causing a loss in altitude and subsequent “DON’T SINK” alert in the cockpit—an aural ground alert for potentially hazardous flight conditions that could result in the aircraft hitting the ground. To recover, the pilots pulled back on the yoke (moves the elevators) but also initiated yoke mounted electric trim to move the stabilizer pitch to a nose-up position.
The elevator is the smaller flap surface attached to the much larger horizontal stabilizer on the tail of the aircraft. The horizontal stabilizer is automatically trimmed for this phase of flight and the pilots use the yoke control column to move the elevator to fly (in pitch along the lateral axis) the aircraft (Figure 1, 2).
While this was occurring, the auto-throttles remained at the 94% (N1 Reference) climb thrust setting. The selection of the Level-Change pitch mode caused the autothrottles (in a climb phase) to reference climb thrust or in this case 94%—thrust remained at 94% for the entire flight. What’s important is that Level-Change is a pitch mode, which means the airspeed is controlled by pitch, not by the autothrottles (they remain in a climb thrust position).
In Level-Change the flight computer generates a “flight-director” reference on the primary flight display that guides the pilots in pitch. With the autopilot disengaged (bad AOA inputs) the pilot must manually follow the guidance. If the pilots maintain the aircraft symbol (small square nose position reference) below the flight director or not superimposed on the center, then the aircraft will accelerate past the selected airspeed (Figure 3).
In this case, together with the autothrottles remaining at 94%, and the fact that MCAS was driving the aircraft symbol reference well below the flight director, the aircraft rapidly accelerated past the pilot-selected airspeed of 238 knots. In fact, the pilots most likely never followed the flight director (pitch guidance) or reduced the thrust which in turn resulted in excessive airspeeds—so excessive that the airspeed clacker alert sounded warning the pilots they had accelerated past the airspeed limit (VMO is 340 knots) for the aircraft—more on this later.
For unexplained reasons—probably because the pilots were overwhelmed trying to deal with the runaway trim—the flight director, power setting, and excessive airspeed were ignored by the pilots. Worse, they made no attempt during the flight to slow down the aircraft. In hindsight, they should have turned off the autothrottles, manually retarded the throttles, and reduced the speed—these critical mistakes (pilot error) would ultimately doom the flight. Moreover, if the aircraft had been slowed to a safe, below flap-extend, speed, extending the flaps would have disabled MCAS auto trim and allowed the pilots to easily manually trim the horizontal stabilizer with the manual trim wheel—an MCAS disabling condition highlighted in Boeing’s bulletin.
Having covered in detail the pilot’s mismanagement of airspeed and power, we should point out that one action might still have saved the day. During climb-out with an emergency, it is standard procedure to level off at an intermediate altitude to address the problem—remember, the pilots had set 32,000 feet in the altitude window. Interrupting the climb profile by leveling off at a lower altitude allows pilots to focus on what needs to be done but, more importantly, prepare them for an immediate return to the airport.
If the pilots had requested a lower altitude after recognizing they had runaway trim and made the initial correction, the aircraft would have leveled off. What would have happened then? The autothrottles would have retarded because the aircraft was in the Level-Change mode and leveling the pitch would have kept the airspeed at 238 knots, which the pilots had set in the airspeed window. The result would have been a much a slower airspeed with significantly less aerodynamic forces on the aircraft’s tail and most likely a more effective use of the manual trim. Whether this would have changed the outcome is uncertain, but it would have controlled the aircraft’s airspeed and eliminated one problem from the pilots’ frenetic agenda.
2) Manual trim became ineffective after the pilots initiated runaway trim procedures
After the pilots recognized the runaway trim, they executed the runaway trim emergency procedure by moving the stabilizer trim switches to cutout (autopilot and electric trim off). For the next two and a half minutes (up to 40 seconds before impact), “the stabilizer position gradually moved in the AND [auto nose-down] direction from 2.3 units to 2.1 units. During this time, aft force was applied to the control columns [drives the elevators] which remained aft of neutral position [because of the heavy nose down force being felt on control column yoke],” as stated in the report. Further, “The left-side indicated that the airspeed increased from approximately 305 kt to approximately 340 kt (VMO)”—the already mentioned certified airspeed limit for the 737 aircraft. But the right side (the correct airspeed) reported an airspeed that was 20-25 knots higher. The correct (right-side) airspeed finished 40 knots (380 knots) above VMO when the final and fatal MCAS-actuated nose-down trim reached its near limit of 40 degrees.
This highlights two critical issues
First, the pilots most likely attempted to use the manual trim wheel(s) (Figure 4), which is part of the runaway stabilizer trim checklist. However, the stabilizer position only moved .02 units to 2.1 units of trim—a very small change. This is not unusual since the trim wheel only makes incremental changes compared to the faster electric trim. The point is that to make enough of a change in the stabilizer position (nose-up) required an aggressive use of the manual trim wheel.
But—and this is important—according to the report, “the stabilizer position gradually moved in the AND [nose-down] direction from 2.3 units to 2.1 units.” This movement is in the wrong direction. It appears that the first officer moved the manual trim wheel nose-down instead of nose-up, further aggravating a nose-down stabilizer position. It should be noted that the captain was the “flying pilot” and the co-pilot was the “monitoring” pilot. The monitoring pilot assists the flying pilot while he or she focuses on flying the aircraft.
Another important point is that the nose-down stabilizer trim position of 2.1 units requires the pilots to move the stabilizer 2-3 units just to get it back to a pre-emergency climb position of 5-6 units—very difficult to do, even with less aerodynamic forces acting on the stabilizer (less than the excessive airspeed force), which occurred in the fatal Lion Flight 610—more on that later. Further, the nose-down position of the stabilizer creates large forces on the control column requiring the pilots to maintain constant aft pressure on the yoke—not easy to maintain and tiring.
This type of emergency takes both pilots acting in concert to accomplish—one flying the aircraft and pulling back on the yoke (at times required by both pilots, as the report indicates) and the other aggressively moving the manual trim wheel. Not to mention, maintaining heading and altitudes, following air traffic control directions, and to the largest contributing [pilot error] factor in this accident—the pilots mismanaged the throttles and airspeed.
This raises the question of how, or whether, Ethiopian Airlines trained its pilots for this emergency
Second, as we have already alluded to, for some reason the pilots let the aircraft accelerate to excessive/extreme speeds. According to the flight control parameter data, the right-side indicated airspeed increased to 380 knots (40 knots above VMO) prior to the last and fatal MCAS-actuated nose-down pitch (Figure 5). We cannot emphasize enough how unusual it is for airline pilots to reach such extreme speeds at low altitude. A mistake that Lion Air flight 43 avoided by keeping their airspeeds below 250 knots, which allowed the pilots to better manage the manual trim—because of the significantly lower aerodynamic force on the large horizontal stabilizer.
At 380 knots, the aerodynamic forces acting on the tail portion of an aircraft (stabilizers and elevators) are enormous, especially at lower altitudes where the air is denser—the aircraft was between 9000 feet and 12,000 feet pressure altitude. The captain’s indications were 20-25 knots lower than the right-side due to faulty AOA signals.
In fact, to the pilots, it would seem like the manual trim wheel was ineffective. This is verified in the exchange between the captain and the first officer (FO) after the stabilizer trim switches were moved to cutout: “At 05:41:46 [one minute and thirty seconds after stabilizer trim cutout], the Captain asked the First Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At 05:41:54 [eight seconds later], the First-Officer replied that it is not working.”
Two major concerns with this exchange
First, was the first officer admitting that he tried to use the electric trim when it was disabled by the stabilizer trim switch being moved to cutout. He replied that “the trim was not working” when asked by the captain “if the trim was functional.” More confusing, he followed the answer with a question, whether he could “could try it manually.” What was the first officer doing for one minute and thirty seconds if he made it seem like he hadn’t used the manual trim? Was he (erroneously) using an ineffective electric trim switch on the control yoke? This trim would have been disabled with the stabilizer trim switches (STAB TRIM CUTOUT) in the off positions.
Second, did he waste one minute and thirty seconds not correcting the stabilizer nose-down position? Why was he not aggressively completing the rest of the runaway trim checklist by grasping the manual trim wheel and correcting the stabilizer? Or did he try to use it and, for some reason, when the captain asked, he made it seem like it hadn’t? Also, while this confusion was occurring, the airspeed had increased by almost 50 knots. Instead of correcting the problem, the pilots were making it worse.
Apparently, the captain didn’t realize that the first officer moved the manual trim wheel in the wrong direction, further aggravating the nose-down position and putting even more pressure on the control column. That mistake is most likely why they stopped using the manual trim wheel and failed to finish the runaway emergency checklist. The appearance of nothing working probably drove them to turn the stabilizer trim cutout switches back on—a desperate attempt to move the stabilizer nose-up but one that would assure their fate.
These subtle mistakes were the difference between flying and losing control of the aircraft
3) Pilots deviated from runaway trim emergency procedures (critical error #2)
After turning off the electric stabilizer trim, the pilots continued to battle for control of the aircraft. Approximately 3 minutes after the STAB TRIM switches were moved to cutout and only 1 minute from hitting the ground, the pilots in frustration (remember, manual trim was ineffective) decided to turn the stabilizer trim switches back on—deviating from the runaway trim emergency procedure, as previously mentioned.
This action would be their last in a series of mistakes
Once the electric stab trim was back on, they quickly initiated the electric yoke mounted trim to relieve pressure on the back stabilizer—remember, the last position of the stabilizer trim was 2.1 units or an aggravated nose-down position. This action was only somewhat successful since according to the report, “two momentary manual electric trim inputs are recorded in the ANU [nose-up] direction,” only moving the [yoke-mounted] stabilizer trim .02 units.
But, as we have highlighted already, MCAS resets five seconds after electric trim is released. So, five seconds after the pilots stopped electric trim, MCAS—still getting faulty AOA signals—initiated a nose-down trim signal to the stabilizer—grossly adding to an already nose-down stabilizer position and eventually creating such an exaggerated nose down trim position that it proved to be unrecoverable (ending up 40 degrees nose down).
Why did the pilots stop using electric trim? The yoke mounted electric trim switches interrupt MCAS and if the pilots had been informed and trained about MCAS as well as runaway trim, as Ethiopian Airlines claims, then they would have known this and aggressively used electric trim to counter the MCAS trim.
There were no more electric trim inputs with only the pilots pulling back on the yoke (elevators)—at this point due to extreme nose-down stabilizer position and excessive speeds, just pulling back on the yoke using the smaller control surface elevator was futile.
An important point, moments before the pilots turned the stabilizer trim switches back on they were still controlling the aircraft and climbing. In fact, they had been steadily climbing for over three minutes using the yoke (elevators). It would take less than 18 seconds after turning on the stab trim to lose complete control of the aircraft.
It begs the question if the pilots practiced the procedure during training at 250 knots or at a much higher speed, how did they incorporate the autothrottles into the emergency? Only Ethiopian Airlines can answer these questions.
4) Crew experience and competency was a major contributing factor
Pilots learn early that experience can make up for a lack of book knowledge and aircraft complexity. Years of empirical data obtained through countless takeoffs and landings provide a seasoned pilot with skill that is hard to quantify. Yet, rarely is it needed. The more technologically advanced and automated aircraft become, the less flying skill is required and the more automation management is needed. The requirement to know about the inner-workings of the aircraft systems are no longer essential because the pilot is disconnected from how computers and software fly the aircraft. However, flying skill and proficiency are still crucial even though, in reality, modern aircraft are forgiving and easy to fly, making the skies safer than ever before.
What happened in these accidents and the pilots’ errors highlight the need to understand the automation and the experience required to master it. Like flying skills, the ability to manage automation is critical for safe flying. Misunderstood or, worse, mismanaged, it can result in tragic accidents. Together, flying and handling the automation is the new norm for pilot experience, especially when the automation is not working correctly and both skills are needed in concert—it is a team effort and, ideally, the team should have similar experience levels. When things go awry, it is the pilot's experience—and standard operating procedures—that will save the day.
In an emergency, it takes one pilot to fly the aircraft and the other to monitor and manage the automation.
The first officer on ET Flight 302 had limited experience: 361 flight hours. This limited background placed additional responsibility (and workload) on the captain who was busy trying to maintain control of the aircraft. The captain depended on the first officer to manage the automation and monitor key tasks, making sure that what the captain asked for was done. Meaning, recognize the problem, go to the correct checklist and execute it, not to mention talking to air traffic control (ATC) and managing the warnings, alerts, messages, and automation—this crew was extremely busy.
When a pilot(s) gets into these high stress and time compressed situations, mistakes can happen. Some mistakes are acceptable but others can be fatal. Here are a few subtle errors that can be very telling about a pilot’s experience and competency—we are not saying the FO was incompetent (he had his hands full) but rather that with limited experience, competency became an important and relative term.
Shortly after takeoff, ATC issued a clearance to Flight level 340, but the FO put 32,000 in the altitude window—and as part of the normal crew coordination both should have verified it. They didn’t double check. It was never verified and only changed when they elected to level off early at 14,000 feet for the emergency.
Also, at the height of the problem, the FO was still answering ATC instructions and inputting heading changes, calling out AOA master caution anti-ice warnings and ignoring the overspeed warning, no doubt because he was overwhelmed. The overspeed warning is a loud aural tone to alert pilots that the aircraft has exceeded its maximum airspeed and is a non-normal checklist item requiring pilots to reduce power and slow down. In fact, by this time, both left and right overspeed warnings were sounding. It appears that the FO’s priorities were on less important issues rather than on assisting the captain with controlling the aircraft.
More importantly, as we have highlighted before but it’s worth repeating, once they recognized the runaway trim problem, the first officer appeared to have moved the manual trim in the wrong direction worsening the nose-down stabilizer position (Figure 6). It was apparent that these actions were not confirmed either, questioning the execution (or completion) of the checklist.
Lastly, as we have pointed out, the crew elected to deviate from the runaway trim checklist (most likely out of frustration, thinking the manual trim was ineffective) and returned the electric STAB TRIM CUTOUT switch to normal (back on)—in direct violation of company procedures. Even though it allowed them to try the yoke-mounted electric trim in a final desperate attempt to correct the nose-down stabilizer position, it also reset the same MCAS (ever-increasing trim reference position) nose-down trim problem. At no time after this did either pilot attempt electric trim.
What this should tell anyone examining this accident is that a lack of experience in one of the seats likely contributed to the final and fatal (pilot error) actions by the crew.
[...]
(continues in next post)
-
The Boeing 737 MAX 8 Crashes: The Case for Pilot Error
https://www.linkedin.com/pulse/boeing-737-max-8-crashes-case-pilot-error-vaughn-cordle-cfa (https://www.linkedin.com/pulse/boeing-737-max-8-crashes-case-pilot-error-vaughn-cordle-cfa)
Another observation
As the report states, “According to Ethiopian Civil Aviation Authority (ECAA) records, the Captain’s most recent simulator training experience was September 30, 2018, and his most recent simulator proficiency check was October 1, 2018.” Further, it states, “…737MAX differences training on 3 July 2018.” It should be noted that there were no dates reported for the MAX series updates provided by Boeing after the Lion Air Crash.
The first officer’s “most recent simulator event was listed as a proficiency check and occurred on December 3, 2018. His line training/check (conducted in the B737 aircraft) was completed on January 31, 2019.” He had only 361 hours of flying, a very low number of flight hours for a major airline. Most U.S. major airlines must have 1000-1500 hours of jet engine time just to apply and fly for a passenger-carrying airline. Pilots normally have thousands of hours before they are hired. Again, there were no dates reported for MAX series updates provided by Boeing after the Lion Air Crash.
What is significant about these dates?
The Lion Air crash occurred on October 29th, 2018. Boeing’s Flight Crew Operations Manual Bulletin for Ethiopian Airlines was issued November 5th, 2018. On March 21st, Ethiopian Airlines tweeted (see below):
Why would the captain’s or first officer’s credentials not reflect the FAA’s Air Worthiness Directive briefing dates or other Boeing information and recommendations sent to Ethiopian Airlines? It would seem prudent to provide these dates in the report to ensure compliance, as stated above.
Yet, the most mysterious missing piece of the Ethiopian accident is the fact that this week (2 April) the Wall Street Journal reported that “according to people briefed on the probe’s preliminary findings, “the crew couldn’t get the aircraft to climb and ended up turning it [stabilizer trim switches] back on [normal position] and relying on other steps before the final nose-down plunge.” Additionally, after further examination of the parameter slide (see Figure 6) it appears they were correct. However, it was never mentioned in the report—why?
There are many questions that need answers to ensure that all contributing factors to this accident are accounted for and properly weighed.
What Ethiopian Airlines Already Knew—Lessons Learned from the Lion Air Flight 610 (LA 610) Accident
The Indonesian preliminary Aircraft Accident Investigation Report is a more thorough review of the accident and provides useful “Findings” and “Safety Actions”—critical information that can help any airline avoid an MCAS-related accident. However, this does not clear Lion Air of pilot or procedural culpability that led to the accident. Like our review of the Ethiopian report, we believe that our analysis of the report’s “Factual Information”, “Aircraft Flight and Maintenance Log” history, and “FDR [Flight Data Recorder] (DFDR) Data” provides strong evidence supporting the view that pilot error was the largest contributing factor.
Like the Ethiopian accident, we can divide our analysis of the LA 610 crash into critical arguments culminating into two fatal pilot errors. Even though the accidents of Lion Air and Ethiopian Airlines have similarities with respect to MCAS issues, they are significantly different in the circumstances leading up to and during the emergency. Because of this, the format used to support these arguments and errors will be presented differently—yet reach the same conclusion: pilot error was the largest contributing factor.
Critical Arguments
1. Previous Lion Air Flight 43 did not pass on critical aircraft information
2. Previous Captains or Maintenance did not ground the aircraft
3. The pilots (crew) identified the wrong checklist
4. The pilots misdiagnosed the runaway trim problem
5. Inappropriate transfer of aircraft control during a critical phase of the emergency
Fatal Pilot Errors
1. Misdiagnosed runaway trim
2. Inappropriate transfer of aircraft control
Important Lessons Learned from the Previous Lion Air Flight 43 (LA 43)
It is important to note that both the captain and first officer of Flight 43 were experienced airline pilots and had almost 10,000 hours in the 737-type aircraft. However, according to reports, Lion Air pilots may not have had the recommended 737 MAX ‘differences training’ required by U.S. carriers.
Another notable point is that there was a third qualified pilot in the cockpit of Flight 43, sitting in the jump seat. These seats are normally reserved for observers when giving pilots ‘check rides’, but if empty can be used by a qualified pilot for travel. The fact that there was a jump seater on this flight would end up being a life-saving factor.
A short history of Lion Air 43 (the flight prior to the doomed Flight 610)
Shortly after takeoff, the report states, “At 400 feet, the PIC [pilot in command or Captain] noticed on the Primary Flight Display (PFD) that the IAS [Indicated Airspeed] DISAGREE warning appeared and the stick shaker activated.” The stick shaker is a physical movement of the control column, designed to alert pilots of an impending stall. In addition—and this was not in the captain’s comments—there was a “Takeoff Configuration Warning” indication, which is a warning designed to alert pilots that the aircraft is not properly configured for takeoff—a serious alert.
Reacting to the airspeed warning, the captain handed over control of the aircraft to the first officer and announced, “memory item airspeed unreliable,” driving both pilots to the “airspeed unreliable” emergency checklist. While this was happening, the first officer noticed after flap retraction that “the aircraft was automatically trimming aircraft nose down (AND),” as stated in the preliminary report. The first officer began fighting for control of the aircraft, by pulling back on the yoke with manual trim to counter the AND (auto nose-down) trim.
In fact, the report findings reveal that the first officer commented, “…the control column was too heavy to hold back,” even though this was never mentioned by the crew in any aircraft write-ups (an ominous similarity that occurred with the fatal Lion Air Flight 610). The result was that the plane immediately went from a state of climbing to losing 100-200 feet, which is significant during the initial climb-out phase of flight. Maintaining control of the aircraft quickly became the priority.
At this point, the crew engaged the autopilot, an action that was absent in the preliminary report “FINDINGS” and only identified on PK-LQP “flight control parameters” slides (refer to Figure 7: The Previous Lion Air Flight 43). The autopilot was most likely engaged to help control the aircraft, a normal procedure during an emergency which allows the pilots to focus on the problem.
No alt text provided for this image
Figure 7: The Previous LA 43: Examination of the Flight Control Parameters
Alone, this action appears routine for emergencies but a closer look at the flight data reveals that the autopilot was quickly disengaged—possibly because turning off the autopilot is the first step in the “airspeed unreliable” checklist. However, the significance of this action is that, as with flap retraction, it stopped the auto nose-down (AND) MCAS trim. For clarification, the MCAS system is activated only when the pilots are flying manually and the flaps are retracted, which is normal on climb-out but cannot be disengaged by only pulling back on the yoke. The crew would engage the autopilot one more time with the same results—and, again, this action disengaged the MCAS trim. The autopilot remained off for the remainder of the flight.
Disconcerting lessons
First, the captain’s transfer of control of the aircraft to the first officer at a very low altitude and before flap retraction is highly unusual. Transferring control in the middle of a developing emergency—during the “critical phase of flight” (initial climb out)—is considered unsafe by most U.S. airline pilots. Most are taught to (1) fly the aircraft and stabilize at a safe altitude, (2) identify the emergency, and (3) run the appropriate emergency checklist(s). Interestingly, the flight data recorder revealed that the stick shaker activated on liftoff, but the captain stated in the report that it came on at 400 feet.
Second, the crew started executing what they thought was the correct checklist based on the stick shaker and the IAS DISAGREE warning. Normally, this would be a good decision had it not been for the [MCAS-activated] auto nose-down trim and subsequent loss of altitude—but the more important issue was the first officer battling for control of the aircraft with a control column too heavy to hold back. Even though this was a complicated and challenging situation with multiple emergency warnings, pilots are trained to prioritize and control (fly) the aircraft first.
Third, (and to restate the importance of prioritizing emergencies, especially in a critical phase of flight) the “airspeed unreliable” procedure may be a memory item as stated by the captain, but, a “runaway trim” event is a higher priority requiring immediate action. It cannot be emphasized enough that when presented with multiple system and flight control problems, flying the aircraft is the priority and addressing lesser priority issues are secondary. This requires thorough training and good judgment. Good judgment comes with years of experience and great training.
Finally, the pilots committed a cardinal sin of aviating: problem-solving. If you get the desired state by moving a switch or control, then keep it there. If retracting the flaps or engaging the autopilot get an undesired condition, then put the switches or levers back where they were (this was a fatal mistake for Flight 610). In other words, once the desired outcome is achieved, leave everything alone.
More lessons from Lion Air 43
As identified in the LA 43 report, “After three automatic nose-down trim occurrences,” the first officer was losing the battle with the aircraft, which, we learned later, resulted in the loss of control and the crash of Flight 610. For LA 43, the good news was that the jump seater recognized the more critical and serious runaway trim problem and suggested moving the “STAB TRIM CUTOUT” switches to CUTOUT. This immediately relieved the problem and begs the question of why it took a jump seater to recognize not only the priority in the cockpit but also to remember the more significant memory item checklist that saved the day. The clear implication is that not all Lion Air pilots are proficient (or properly trained) in recognizing and dealing with a runaway trim problem.
Flying the aircraft and confirming the emergency are THE critical first steps during an emergency. The failure to identify the critical problem and safely control the aircraft (and its systems) is, by definition, pilot error.
Also, the Flight Data Recorder (FDR) revealed that faulty AOA sensors were already feeding bad data to the flight control computers during takeoff: faulty AOA signals on takeoff role; stick shaker on liftoff; Takeoff Configuration Warning after gear retraction; and IAS DISAGREE alert shortly after gear retraction. Together, these presented a complicated and challenging situation for the pilots—and an event that exposed the flight control problems of the MCAS and its MAX 8 AOA sensor logic.
As a fix, following the Lion Air crash, Southwest Airlines (the largest U.S. carrier of the 737 MAX) decided to include a new AOA indicator on the pilot Primary Flight Display (PFD) to safeguard against faulty AOA sensor data (Figure 8). The new indicator provides “continuous visual feedback to the Flight Crew allowing identification of erroneous AOA sensor input that could lead to un-commanded stabilizer trim actuation,” according to an internal message provided to Southwest pilots.
No alt text provided for this image
Figure 8: Primary Flight Display (PFD) with AOA indicator and disagree warning
However, after examining the indicator and where it is displayed in the cockpit, we can attest that it provides little value during an emergency when the electric stabilizer trim is running away and controlling the aircraft is in question. The indicator, along with an AOA disagree warning message, was an option (at additional cost) to the airlines. Most airlines—and this includes Lion Air and Ethiopian Airlines—decided not to purchase it and for good reason.
When presented with flight control problems, as was identified by the fatal Lion Air Flight 610 crew, pilots are trained to monitor and scan the primary flight indicators which are airspeed, altitude, and pitch (and at low airspeed the Pitch Limit Indicator shown above), not an AOA indicator. It is not a primary flight instrument and is only used as an additional reference (time permitting). It’s akin to wasting time referencing the oil pressure gauge when the pilot should be focused on recovering from an upset aircraft condition.
Moreover, the rationale for incorporating the AOA indicator and disagree light for identifying “erroneous AOA sensor input that could lead to un-commanded stabilizer trim actuation,” as stated in an internal message provided to Southwest pilots, could lead the general public (and media) to believe that it’s a critical indicator for flight.
In our view, we do not believe that this indicator, if installed, would help the pilots to identify and stop a runaway stabilizer trim—most airlines currently do not have this indicator installed on any of their aircraft—and airlines have already flown the MAX aircraft for thousands of hours accident-free. The AOA indicator option offered by Boeing has been touted in the media as a questionable (cost-saving) shortfall by carriers; the truth is that it doesn’t help the pilots fly the aircraft.
Review: AOA inputs for flight guidance on the PFD and HUD
The primary flight indicators for which the Angle of Attack (AOA) sensor provides input include the Pitch Limit Indicator (PLI), which is graphically displayed on the Primary Flight Display (PFD), and the Angle of Attack Limit, which is displayed on the head-up display (Figure 9).
The PLI graphically displays the proximity of the stick shaker activation point (nearing a stall speed pitch) in relation to the aircraft’s current pitch attitude for existing flight conditions. On the HUD, the distance between the Angle of Attack Limit symbol and the flight path vector symbol is the margin available to the stick shaker.
The flight path vector symbol is similar to that on the PFD, with some minor differences. Information, derived from the inertial sources, indicates where the airplane is going. The position of the center of the flight path circle relative to the pitch scale indicates the flight path angle.
No alt text provided for this image
Figure 9: Head-up display (HUD), flight director guidance cue and flight path vector symbol
The guidance cue (the small circle shown on the HUD display) is associated with the flight path vector symbol. Displayed when the flight directors are turned on, it provides flight director guidance. Positioning the circular body of the flight path vector symbol around the guidance cue causes the aircraft to follow the flight director guidance.
The angle-of-attack (AOA) limit symbol is referenced to the flight path vector symbol, whereas the pitch limit indicator on the PFD is referenced to the airplane symbol.
The distance between the AOA limit symbol and the flight path vector symbol represents the margin available to the stick shaker (Figure 10). It is displayed during any of the following: angle-of-attack is within 5° of the stick shaker, whenever the stick shaker is active, or whenever the wind shear (solid) guidance cue is displayed.
No alt text provided for this image
Figure 10: Head-up display (HUD), AOA limit indicator
Pilots are trained to look at the airspeed and pitch references on the PFD and the AOA limit symbol on the HUD to fly the aircraft—the new AOA indicator (and warning) on the PFD is NOT a flight indicator as some appear to believe. Southwest’s 737 MAX aircraft have the HUDs installed but not all operators have elected to install the drop-down glass screen. The optional AOA indicators are not activated on the airlines Next Generation (NG) 737 fleet.
Back to LA 43: Judgment
After noticing the warning lights, running through the lesser priority checklist, and the stabilizer trim being cutout (by the jump seater), the pilots still elected to continue to their destination. As major airline pilots, we can tell you that if there are known flight control problems and emergency checklists involved, then the best decision is to “plan to land at the nearest suitable airport”—even if it does not specifically say this in the checklist. It’s called judgment. Why was it absent? It is drilled into U.S. pilots, to the point of common sense.
The pilots disregarded their flight control problems and continued the flight
At cruising altitude, the Lion Air pilots reported to air traffic control an autopilot and altitude failure. This forced them to level off at 28,000 feet because, without the autopilot (the autopilot was disabled when the stabilizer trim cutout switch was moved to CUTOUT), they could not go above 29,000 feet in RVSM (Reduced Vertical Separation Minimum) airspace (another unusual pilot decision). RVSM reduces the vertical separation required between aircraft to allow more aircraft to travel in close proximity, but it requires equipment such as a functional autopilot. The pilots maintained this cruising altitude and proceeded to their destination disregarding the multiple emergencies that had occurred during the flight—essentially, they continued with a crippled aircraft.
More than a few mistakes were made by the Lion Air pilots
Good judgment suggests that the pilots should have landed at the nearest suitable airfield. Most emergencies in complex aircraft tend to have several related failures along with the primary issue. In other words, there are compounding problems, as was the case in LA 43. For U.S.-carrier trained pilots, this could be considered gross negligence.
So, why did the Lion Air pilots act differently than U.S. trained pilots? Why was this aircraft not grounded by the crew or maintenance? Why didn’t the captain write-up the runaway trim, excessive control forces, and the fact that the stabilizer trim cutout switches were moved to cut-out, which solved the problem? We will address these questions shortly.
Fatal flight: Lion Air 610
Like LA 43, the pilots of LA 610 experienced an aggressive nose down trim and a loss of several hundred feet. This occurred on climb-out and immediately after the flaps were retracted. The preliminary report states, “After the flaps retracted, the FDR recorded automatic aircraft nose down (AND) trim active for 10 seconds followed by flight crew commanded aircraft nose up (ANU) trim.”
As with the previous flight, during takeoff rotation, the left control column stick shaker activated and continued for the entire flight. Also, the same IAS DISAGREE warning appeared on the captain’s Primary Flight Display (PFD). We have already pointed out that a stick shaker on takeoff, even though it can be associated with an IAS DISAGREE warning, is troubling and should have led to the plane returning to the departure airport.
However, in defense of the pilots’ initial reaction to the problem, the combination of the IAS DISAGREE warning and stick shaker likely took them to a lesser priority checklist, just as it did with the pilots of LA 43. Had they also known about the MCAS system and that a faulty AOA, together with unreliable airspeed warnings, could drive both a stick shaker activation and a severe nose down trim, an early diagnosis of the real problem might have led to a different outcome. In other words, if the pilots had known about MCAS and its (anti-stall) purpose, as well as the effect of the faulty AOA signals, perhaps they would have been better prepared to handle a runaway stabilizer trim.
One further point concerning pilot judgment: according to the preliminary report, the pilots responded to nine heading changes by Air Traffic Control (ATC), four altitude requests, and one heading change initiated by the pilots for weather—all of which may have further distracted them. Again, it is not unusual for ATC or pilots trying to find an area (“some holding point”) to work declared “flight control problems” or to position them back for an immediate landing—but, instead of taking the initiative, declaring an emergency and being directive (in the U.S. ATC is very flexible when an aircraft declares an emergency, letting the pilots maneuver as needed), they continued to follow ATC directions while trying to maintain control of the aircraft.
The critical life-saving action that would have saved the passengers and crew
Running a lesser priority checklist and misdiagnosing the problem is serious enough, but the crew of the fatal crash did something that was highly unusual, which, if not done, might have saved their lives and the lives of everyone else on the aircraft.
After the flaps had retracted, the pilots put the flaps back down, guess what happened? The nose down trim stopped, as stated in the preliminary report: “After the flaps retracted, the FDR recorded automatic aircraft nose down (AND) trim active for 10 seconds followed by flight crew commanded aircraft nose up (ANU) trim. The flaps extended to 5 and the automatic AND trim stopped” (refer to Figure 11: The Fatal Lion Air Flight 610).
No alt text provided for this image
Figure 11: Lion Air Flight 610: Examination of the Flight Control Parameters
If this solved the problem, then why did the plane crash seven minutes later?
The pilots, once again, committed a cardinal sin of aviating: problem-solving. If you get an undesired state by moving a switch or control, in this case retracting the flaps, and it solves the problem, then leave it where it is. Why didn’t they extend the flaps to their original position, which would have returned the aircraft to the desired state by stopping the runaway trim? With the benefit of hindsight, the pilots should have slowed the aircraft and put the flaps back down, left them down and proceeded back to the airport for a (declared) emergency landing. Instead, they left the flaps up for the entire flight, battling the aircraft all the way to impact.
Sadly, it didn’t stop there
Based on numerous reports—although not identified in the Indonesian preliminary report—the captain, at the height of the nose-down trim problem, nearly a minute before the crash, handed over the flight controls to the first officer. To be fair, this alone is not unusual. In fact, it is standard practice for U.S. carriers during emergency situations. What is different (as with Flight 43) is that handing over the flight controls during a critical phase of flight, while fighting a severe flight control problem, especially one that had most likely developed into severe control column (yoke) pressure, is extremely poor judgment.
The mistake of transferring control
We believe that a typical U.S. trained pilot would not transfer control of the aircraft to another pilot if there was a serious flight control problem. The non-flying pilot would have no feel of the flight control (excessive at that time) or what the flying pilot might have been experiencing to get out of the dire situation. Even the flight data recorder shows, “the final control column inputs from the first officer were weaker than the ones made earlier by the captain.”
To make the point clear: it would be like flying upside down in an aircraft at low altitude, with little altitude to recover, and the other pilot blindfolded (remember, he was most likely head down, frantically trying to find the right checklist), handed the flight controls and told to recover. We believe that no experienced or properly trained pilot would have transferred control of the yoke to the non-flying pilot under these critical circumstances.
The previous four
The Indonesian preliminary report goes over the maintenance write-ups of the previous four flights of the fatal aircraft. Every one of these flights experienced similar problems that were documented in the maintenance flight log.
Here is a synopsis of the flight maintenance log write-ups
“The Aircraft Flight Maintenance Log (AFML) recorded that since 26 October 2018 until the occurrence date (29 October) several problems occurred related to airspeed and altitude flag appeared on Captain (left) Primary Flight Display (PFD) three times, SPEED TRIM FAIL light illumination and MACH TRIM FAIL light illumination two times and IAS (Indicated Airspeed) and ALT (Altitude) Disagree shown on the LA 610 Denpasar to Jakarta the day before the accident flight.”
Further, the captain on the previous LA 43 wrote up the problem, even mentioning the “STS [speed trim system] running in the wrong direction…” However, he didn’t mention the use of the STAB TRIM CUTOUT switches that solved the problem. Ironically, maintenance changed the AOA sensor, not because of multiple aircraft write-ups but because they couldn’t repeat the errors during maintenance checks and considered replacing the AOA prudent. A good decision.
Important Review: One major MCAS shortcoming is that Boeing designed the system to receive input from only one of the AOA sensors during each flight. The left and right sensors alternate between flights, sending AOA data to the Flight Control Computers (FCC) and the MCAS. Instead of designing a redundant system where the aircraft would use another AOA sensor in case of faulty data or failure, Boeing allowed only one sensor to send data.
The critical point is that after four previous flights had experienced similar problems that were written up and the fact that an immediate action procedure of runaway stab trim was used to solve the flight control problem, the captain failed to write-up the use of the stab trim switches. In fact, why were other significant problems with the aircraft not fixed or the aircraft grounded? It is one thing for maintenance to get a non-repeat test of the system once, but four times? Moreover, why didn’t successive captains, who are the last line of defense in ensuring an aircraft is safe to fly, address these critical problems with maintenance and ground the aircraft? Though not deliberate, such omissions would be considered negligent by U.S. airlines.
One final question and thought about Ethiopian Airlines Flight 302
After reviewing the Indonesian report, it begs the question: If Ethiopian Airlines had (1) all the pertinent information from the Lion Air accident report as well as (2) Boeing’s recommendations and MCAS information, then how could their pilots have crashed under similar conditions? How does one account for this—it’s a question that only Ethiopian Airlines can answer.
CONCLUSION
Examining both accidents separately provides valuable insights—it’s easy to understand how these unrelated airlines and crew may have responded in similar ways—but the overall conclusion in our previous article, “Boeing’s Grounding: Catastrophic Crashes, and Questions About Boeing’s Liability And 737 MAX Aircraft Viability,” still stands—the major contributing factor to these accidents was pilot error.
After a more comprehensive analysis of each of the two accidents, especially Lion Air Flight 610, we are persuaded more than ever that the case for pilot error—as well as inadequate training—are the dominant contributing factors in both accidents, not the only ones but the most serious factors.
The LA 610 accident is somewhat excusable since the pilots were not privy to MCAS and its challenges. Even so, there were surprising pilot practices and judgment shortfalls as well as concerns with appropriate MAX training. The Ethiopian accident, however, is more confounding since it was verified by the airline that the pilots were trained in accordance with Boeing (and FAA) recommendations. Perhaps the company’s training verification should be scrutinized.
As we have highlighted, the ET 302 pilots did follow the runaway trim procedure, at least initially. However, questions remain as to why the pilots mismanaged the airspeed and deviated from company and Boeing procedures. These actions led to an unrecoverable dive resulting in the loss of crew and passengers. We believe that the final accident report will (or should) reflect this finding.
We need to know why these accidents occurred
Thousands of planes with hundreds of thousands of passengers fly each day. Every accident, tragic as it is, is a learning moment for pilots and the airlines that train them. You can be sure that every airline pilot has now looked at the manuals for runaway trim to make sure they know the procedures as well as they can. If we seem hard on pilots, we are! The profession is not for the faint of heart or thin of skin. In those rare instances when things go wrong, the lives of hundreds of people depend on the pilot’s quick thinking, knowledge, experience, and skill—in a word, expertise.
Equally important, pilots depend on the aircraft manufacturer’s design of the flight control systems and automatic features that actuate when required. These systems and their designs are critical for safe flight. This is why Boeing must be held accountable for any [safety analysis] 737 MAX certification shortcuts that may have occurred. We know that Boeing did not test the MAX to gauge how pilots would react in the event that a malfunctioning sensor triggered the automated system—according to acting FAA Administrator Daniel Elwell when he testified in front of a Senate panel recently. The flying public and airline crews need to know why the MCAS was not more fully tested during the safety analysis required for certification. Only Boeing and the FAA can address this issue.
Piloting is a complex profession with strict rules, standard operating procedures, and training. Pilots have sole responsibility for their passengers and crew, which is why they spend so much time training for the unexpected. Problems need to be identified and corrected in seconds, sometimes in fractions of a second. When pilots most need it, time is never plentiful.
Safety is every pilot’s priority—everything else is secondary.
-
Does this guy shit on his bench? It looks disgusting.
https://www.youtube.com/watch?v=NhZ0D-JRtz0 (https://www.youtube.com/watch?v=NhZ0D-JRtz0)
-
It is always expedient to blame the pilot or train engineer when they are dead.
Witness The wreck of the Old 97 (https://en.wikipedia.org/wiki/Wreck_of_the_Old_97).
There was a deadly derailment in Spain in 2013 (https://en.wikipedia.org/wiki/Santiago_de_Compostela_derailment). A high speed train going at twice the posted speed derailed killing 80. The engineer was blamed for not lowering the speed. Fortunately or unfortunately he survived. All the blame was put on the engineer but the fact is that the engineer had warned that the automatic speed limiting system present in other parts should be implemented there or an accident was bound to happen. The engineer was distracted because he was talking business on the phone with the train conductor as part of his job. The whole system was messed up by the railway trying to save money and they should have installed the automatic speed limiting system and had a helper with the engineer.
https://youtu.be/tQDq_gr2qTY?t=1
And, of course, the trial put all the blame on the engineer and none on the company. The engineer was charged with 79 counts of manslaughter caused by professional recklessness and an undetermined number of counts of causing injury by professional recklessness, for which he was sentenced to 4 years in jail. We live in a fucked up world.
Boeing was trying to save time and money and gain sales so they cut corners. The 737 Max are grounded worldwide and that speaks volumes. If the planes are not at fault why have they been grounded by every country?
-
Jesus Christ! The pilots kept accelerating moar and moar and trimmed it even further nose down. Name a thing they did well please.
-
It is always expedient to blame the pilot or train engineer when they are dead.
Witness The wreck of the Old 97 (https://en.wikipedia.org/wiki/Wreck_of_the_Old_97).
There was a deadly derailment in Spain in 2013 (https://en.wikipedia.org/wiki/Santiago_de_Compostela_derailment). A high speed train going at twice the posted speed derailed killing 80. The engineer was blamed for not lowering the speed. Fortunately or unfortunately he survived. All the blame was put on the engineer but the fact is that the engineer had warned that the automatic speed limiting system present in other parts should be implemented there or an accident was bound to happen. The engineer was distracted because he was talking business on the phone with the train conductor as part of his job. The whole system was messed up by the railway trying to save money and they should have installed the automatic speed limiting system and had a helper with the engineer.
https://youtu.be/tQDq_gr2qTY?t=1 (https://youtu.be/tQDq_gr2qTY?t=1)
And, of course, the trial put all the blame on the engineer and none on the company. The engineer was charged with 79 counts of manslaughter caused by professional recklessness and an undetermined number of counts of causing injury by professional recklessness, for which he was sentenced to 4 years in jail. We live in a fucked up world.
Boeing was trying to save time and money and gain sales so they cut corners. The 737 Max are grounded worldwide and that speaks volumes. If the planes are not at fault why have they been grounded by every country?
Gaaaaah! You cant say that! Its forbidden! Its grounded because its the pilots fault! Always pilots faults newer big business, they are to holy, big time money, follow the money and blame everyone for what you are doing!
Deepstates rules! When hell is full the clowns will walk the earth! Honk Honk!
https://www.youtube.com/watch?v=Z4OhbzSFpnk (https://www.youtube.com/watch?v=Z4OhbzSFpnk)
-
The Boeing 737 MAX 8 Crashes: The Case for Pilot Error
< copy pasta wall of text possibly showing pilot mistakes>
How much is Boeing paying their shills now, to promote the narrative of blaming the pilots?
Boeing's multi-billion dollar turd needs a lot more perfume.
CEO Dennis Muilenberg needs to resign. He's not admitting to anything and is adamant they've done nothing wrong :bullshit:
-
I don't think they're paying anybody to write anything, but yeah, that CEO is a douchebag, reminds me of John Sculley.
-
Does this guy shit on his bench? It looks disgusting.
He's not an EE. He is a machinist. What else do you expect?
If he has a super neat, oil-free bench top, more likely than not he also has a bunch of corroded tools.
One reason I donated the right of use of my CNC to my workplace is for this exact reason.
It's just too messy at home, and it's a tiny one. AvE has a Haas in his backyard.
For the purpose of Youtube he is a content maker. A visit to a dollar store would give him a roll of 100 feet paper for a dollar. Just use a new clean piece for next video, bench hygiene problem is solved.
-
Does this guy shit on his bench? It looks disgusting.
He's not an EE. He is a machinist. What else do you expect?
If he has a super neat, oil-free bench top, more likely than not he also has a bunch of corroded tools.
One reason I donated the right of use of my CNC to my workplace is for this exact reason.
It's just too messy at home, and it's a tiny one. AvE has a Haas in his backyard.
For the purpose of Youtube he is a content maker. A visit to a dollar store would give him a roll of 100 feet paper for a dollar. Just use a new clean piece for next video, bench hygiene problem is solved.
come on, it is basically a film set. The green mat is his signature and the marks and spots shows the history of previous experiments done on video
-
Jesus Christ! The pilots kept accelerating moar and moar and trimmed it even further nose down. Name a thing they did well please.
Maybe the reason they did not react correctly is because they had not trained for such an event. And maybe the reason they had not trained for such an event is because Boeing had said it could not happen and they had further said no further training was needed to pilot the 737 MAX?
And maybe the Air traffic administrations of all the countries in the wide world all agreed that the plane was not safe to fly by any pilots, no matter how good, and therefore all 737 MAX should be grounded?
And maybe they said the 737 MAX would not be allowed to fly until it was further certified. You know, the plane.
And maybe Boeing recognized the plane was unsafe and added sensors which until the day before the crash were considered and "optional luxury package".
But, hey, even though Boeing has admitted through its actions that they are at fault, you can keep defending them. I suggest you write Boeing and tell them they are wrong in doing that and they should insist their planes were safe and all this is a world wide confabulation against them.
-
To say that the pilots did it wrong, is not to defend Boeing.
-
Does this guy shit on his bench? It looks disgusting. https://www.youtube.com/watch?v=NhZ0D-JRtz0 (https://www.youtube.com/watch?v=NhZ0D-JRtz0)
It’s a running gag on the channel, calling his shop the “empire of dirt”.
-
The "rat" look is sometimes what people want. Metal chips, coolant, oil, grease are messy. AvE's slang also seems to be part of a rough, unrefined approach contrasting the precise works that he's looking at. I've seen a few youtubers take on a persona to stand out.
That particular AoA sensor is primitive engineering by any means.
The slip-ring on the Litton resolver looks like something out of a cheap toy motor, with a bit of gold plating. Why isn't it brushless?
Open gears? Put them in a gearbox so any particles don't jam the sensor. How about a double seal on some bearings.
I bet the thing is worth a small fortune but reliability isn't there. Something is wrong with the Rosemount/UTC AoA sensors on the max.
ET302 suspected a bird hit it and broke off the vane but the engine intake is nearby with no fan damage? and the erroneous readings are not consistent with a broken vane.
-
The "rat" look is sometimes what people want. Metal chips, coolant, oil, grease are messy. AvE's slang also seems to be part of a rough, unrefined approach contrasting the precise works that he's looking at. I've seen a few youtubers take on a persona to stand out.
That particular AoA sensor is primitive engineering by any means.
The slip-ring on the Litton resolver looks like something out of a cheap toy motor, with a bit of gold plating. Why isn't it brushless?
Open gears? Put them in a gearbox so any particles don't jam the sensor. How about a double seal on some bearings.
I bet the thing is worth a small fortune but reliability isn't there. Something is wrong with the Rosemount/UTC AoA sensors on the max.
ET302 suspected a bird hit it and broke off the vane but the engine intake is nearby with no fan damage? and the erroneous readings are not consistent with a broken vane.
how would you get power to the rotor without brushes? gearbox and bearing seals, why? it is a sealed unit
They have provably used the same sensor for 50 years with no issues
-
How Boeing’s 737 MAX Failed
The plane’s safety systems, and how they were developed, are at the center of the aerospace giant’s unfolding crisis
By Andy Pasztor, Andrew Tangel, Robert Wall and Alison Sider
Boeing Co. needed the redesign of its crucial 737 jetliner to go swiftly and smoothly, so it pursued a path that reduced regulatory scrutiny and accommodated its biggest customer by requiring as little new training for pilots as possible.
Many pilots now say Boeing’s choices for the 737 MAX left them in the dark about a new feature whose malfunctioning has been implicated in one deadly crash and is under scrutiny for a possible role in a second—disasters that claimed 346 lives.
Pilots flying the 737 MAX, which entered service in 2017, received no training on a new stall-prevention system and saw almost no mention of it in manuals, according to the pilots and industry officials. Most would get no visible cockpit warnings when a sensor used to trigger the system malfunctioned, and they had no access to simulators that could replicate the kinds of problems believed to have downed Lion Air Flight 610 in October.
Following the second crash, in Ethiopia this month, a picture is emerging that suggests Boeing, as it hurried to get the plane on the market, put too much faith in its design and engineering, particularly of the automated stall-prevention system that was supposed to make the plane safer, according to interviews with safety experts, industry officials, former Boeing employees and former regulators.
Many questions remain about Boeing’s handling of the redesign and what went wrong. The Justice Department and other federal agencies are investigating whether Boeing provided incomplete or misleading information to get the airliner certified as safe to fly.
Ethiopian investigators have yet to detail their preliminary findings, although authorities have cited similarities between both crashes. Ethiopian Airlines’ chief executive has said the stall-prevention system, called MCAS, appears to have played a role.
The first of what is expected to be a series of congressional hearings looking at the decisions of both Boeing and the Federal Aviation Administration began on Wednesday.
Boeing has said it would overhaul the flight-control system and make safety alerts that had been optional a standard feature. The fix has been undergoing flight trials since Feb. 7, Boeing said, before the Ethiopian airliner crashed.
A Boeing official said Wednesday the software change didn’t mean the original MCAS design was inadequate, but that the company “found a way to make it more robust.” He also said Boeing was conducting reviews of other MAX flight-control systems but hadn’t uncovered any potential problems.
There are indications that Boeing was aware that some 737 MAX models in the air lacked all the possible safety features available.
How the 737 MAX Became Boeing’s Fastest-Selling Plane
Boeing’s 737 MAX evolved to meet surging international demand for air travel and in the process became its top-selling plane. WSJ’s Jason Bellini looks at how the grounding of the fleet following the Ethiopian Airlines crash could have a significant impact on Boeing’s future. Photo: Getty
On Nov. 27, about a month after the first crash, Boeing executive Mike Sinnett told American Airlines ’ pilot union that their pilots wouldn’t experience the sort of problems that doomed the Lion Air flight, according to Dan Carey, union president. That's because American paid for an additional cockpit warning light that would have alerted them to the problem, while Lion Air and most other airlines didn’t.
Cockpit indicators
“This wouldn’t have happened to you guys,” Mr. Carey recalled Mr. Sinnett saying during the meeting. The cockpit indicators would have directed pilots to have the potential problem checked out on the ground. A Boeing spokesman said Mr. Sinnett didn’t recall making that statement, and was unavailable for an interview.
The Boeing spokesman said the company followed “established and accepted assumptions and processes” in designing and certifying the new stall-prevention system. He said Boeing “determined that a pilot would be able to counteract erroneous system input” by following established procedures for which pilots have received training previously.
Boeing said the FAA considered the system’s final design during its certification of the aircraft and concluded that it met all regulatory requirements.
One senior Boeing official said the company had decided against disclosing details about the system that it felt would inundate the average pilot with too much information—and significantly more technical data—than he or she needed or could realistically digest.
It is Boeing’s biggest crisis in years. The 737 has been the centerpiece of Boeing’s business for decades, and the MAX was intended to carry that on. Now the entire 737 MAX fleet is grounded. Industry executives and former regulators say it could take years for the company to rebuild trust among airlines, pilots and foreign regulators. The fallout could affect the way the FAA monitors the development and approval of new aircraft essential for airlines to meet soaring global demand for air travel.
Boeing needed the MAX to offer a fuel-efficient option for customers to avoid losing market share to chief rival Airbus SE . Boeing didn’t even wait for its board of directors to approve the design before offering it to American Airlines, which was on the cusp of buying planes from Airbus. Boeing’s board didn’t formally sign off on the MAX until a month later.
“Design, development and certification was consistent with our approach to previous new and derivative airplane designs,” Boeing said.
Boeing engineers realized the MAX needed engineering changes from the existing 737s to accommodate its larger, fuel-efficient engines. The engines made the new plane tougher to fly in certain conditions than the 737s already in service, according to people familiar with the plane’s development. To help pilots manage that, Boeing decided to add the MCAS stall-prevention system.
In the Lion Air crash, the stall-prevention system, based on erroneous sensor information, repeatedly pushed the plane’s nose down. According to a preliminary accident probe, the pilot battled the flight controls while facing a cacophony of alarms before losing control and plunging into the Java Sea.
Some former Boeing engineers, safety experts and pilots said that while the system was conceived to enhance safety, the design fell short.
Minimizing changes
Throughout the MAX’s development, Boeing was intent on minimizing design changes that could require extra pilot training, said Rick Ludtke, a former Boeing engineer who worked on 737 MAX cockpit features but not the MCAS system. Extra training could have added costs for airlines introducing the MAX into service.
The company had promised Southwest Airlines Co. , the plane’s biggest customer, to keep pilot training to a minimum so the new jet could seamlessly slot into the carrier’s fleet of older 737s, according to regulators and industry officials.
Mr. Ludtke recalled midlevel managers telling subordinates that Boeing had committed to pay the airline $1 million per plane if its design ended up requiring pilots to spend additional simulator time. “We had never, ever seen commitments like that before,” he said.
Southwest, which has ordered 280 MAX aircraft, declined to comment on the issue, as did Boeing. A Southwest spokeswoman has said the airline developed its 737 MAX training based on Boeing’s information and was a recipient of, not a driver of, the training mandates.
Boeing employees at the Renton, Wash., factory last year celebrated the 10,000th 737 to come off the production line. PHOTO: BOEING
It was difficult for Boeing to figure out what changes it could make without triggering the need for more training, Mr. Ludtke said, in part because of the FAA’s approval process.
According to Mr. Ludtke and a U.S. government official, the agency would evaluate the entire plane only after it was complete, and wouldn’t give step-by-step guidance on what would or wouldn’t lead to additional training demands. That added pressure on Boeing’s engineers to keep changes to a minimum, he said.
The FAA has said that the 737 MAX was approved as part of the agency’s standard certification process.
The MAX planes entered service before the first flight simulators were even ready for use by airlines, according to airline executives, and the few that have now been introduced can’t replicate the malfunction the Lion Air crew faced. The simulators are set to be enhanced to allow pilots to practice dealing with such failures, though the upgrade could be months away.
Following the Lion Air crash, Boeing said that pilots are routinely trained to respond to erroneous automated nose-down pushes regardless of the cause and turn off related systems. The company has told pilot groups and others that the system behaves similarly to the ones in an earlier generation of 737s. It said it discussed the MCAS system’s functions at several airline conferences in recent years and wrote manuals to include information it believed pilots needed to operate the aircraft safely.
Numerous pilots and safety experts interviewed by The Wall Street Journal said that in practice, amid the chaos of an aircraft lurching into a steep dive with emergency warnings blaring, it is unrealistic to expect pilots to recognize what is happening and respond almost instantaneously.
Debris from the crash this month of the Ethiopian Airlines Boeing 737 MAX. PHOTO: BAZ RATNER/REUTERS
Bryan Lesko, an airline pilot who wrote an article last year for his union’s magazine about the 737 MAX, repeatedly asked Boeing officials if there were any major new systems. The answer was no, according to a person who recently discussed the matter with him. The union declined to make Mr. Lesko available for comment.
Since the stall-prevention system emerged as a potential factor in the Lion Air crash, industry and government officials around the world have learned that the system can in certain situations push the plane’s nose down repeatedly, undercutting the pilot’s ability to regain control manually.
A software overhaul Boeing is set to distribute to airlines in the coming weeks will address that problem.
An earlier design decision by Boeing engineers was intended to make the stall-prevention system simple. It relied on data from a single sensor, rather than two, to measure the angle of the plane’s nose, Boeing said.
Safety experts, pilots and some former Boeing engineers say it is rare for aircraft to rely on just one sensor for almost any system whose failure could cause a crash. A sensor malfunction was implicated in the 2009 crash of Air France Flight 447, when an iced-up airspeed sensor triggered a series of events that caused the plane to plunge into the Atlantic.
“If your airplane needs such a Band-Aid, then it is incumbent on you to make sure it’s a good Band-Aid,” said Frank McCormick, a former Boeing flight-controls engineer who became a consultant to regulators and manufacturers before retiring.
Boeing 737 MAX airplanes were designed to be a fuel-efficient competitor to those of the company’s chief rival, Airbus. PHOTO: LINDSEY WASSON/REUTERS
The Boeing spokesman said the plane maker’s analysis determined that a pilot would be able to address the flight-control system misfiring with switches to counteract it or turn it off. “Single sources of data are considered acceptable in such cases by our industry, and additional changes to the system were not deemed warranted,” he said.
An FAA-sponsored panel of international safety experts years ago concluded that crew training tended to stress that computers typically handle unusual situations more smoothly and effectively than the pilots. “There is a natural reluctance to turn [systems] off, because it’s not clear what else is being turned off,” said Ray Valeika, a retired senior maintenance and engineering official at Delta Air Lines Inc.
Boeing is changing its approach to provide pilots with information about the sensors that measure the angle of a plane’s nose.
Boeing has long argued that such angle-of-attack information wasn’t necessary for crews to safely operate aircraft, and that other data such as altitude and airspeed were more relevant. Over the years, a few carriers, such as American Airlines and Delta, have pushed Boeing to provide its pilots additional angle-of-attack information, according to an airline official.
In the wake of the Lion Air and Ethiopian Air crashes, Boeing now is making the alerts standard on the MAX, rather than as a paid option.
The promised software fixes for the 737 MAX amount to reversal of key Boeing design decisions in developing the plane. With the new software in place, the stall-prevention system will rely on data from two sensors, not one, and won’t activate if the data from those angle-of-attack sensors doesn’t match.
—Ben Otto, Jim Oberman and Elisa Cho contributed to this article.
-
how would you get power to the rotor without brushes? gearbox and bearing seals, why? it is a sealed unit
Brushless resolvers work with the drive coil on the stator and the rotor is just a piece of steel shaped such that it alters the coupling between the drive coil and sense coils as it turns.
-
how would you get power to the rotor without brushes? gearbox and bearing seals, why? it is a sealed unit
Brushless resolvers work with the drive coil on the stator and the rotor is just a piece of steel shaped such that it alters the coupling between the drive coil and sense coils as it turns.
are you sure?
-
AoA sensors seem to experience wide temperature swings, water, ice, birds, lightning and static discharges - so they don't use semiconductors in them. Old Russian AoA sensors use a quad wirewound potentiometer.
My beef is any loose strand of wire, plastic or metal chip can get in the gears, stick to the lube and cause troubles. There's so much manual assembly that a flake of anything could get loose. Why is it constructed like a Grandfather clock?
I find setscrews are terrible for holding something to a shaft, like a gear on a shaft. Dissimilar metals, like steel and aluminum expand/contract at different rates and they work loose. There's no chromate finish or Alodine in the AoA sensor that AvE takes apart. I could go on, but the Rosemounts look cheap and antiquated.
AoA manufacturing error FAA directive for Cirrus jets with Aerosonic AoA sensor (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/448c46c035e93a6e862583e0007291d8/$FILE/2019-08-51_Emergency.pdf) where the vane setscrew was not properly tightened and no Locktite applied.
Oh look, another copy pasta wall of text. Just a reminder, the stance is:
"Muilenburg insisted that MCAS system “was designed per our standards” and followed proper certification procedures."
Boeing was unable to find any "technical slip or gap" in building its MCAS software.
Relying on one sensor is going to be interesting to defend, Mr. CEO.
-
The pilots are the last line of defense.
-
The pilots are the last line of defense.
And the first to blame, right? :o
-
The plane had a fault but did not have to crash... Blame Boeing for the fault, blame the pilots for their wrongdoing.
-
Russian style AoA sensor, 4 potentiometers:
https://www.youtube.com/watch?v=Yw39LGwxqBU (https://www.youtube.com/watch?v=Yw39LGwxqBU)
-
The plane had a fault but did not have to crash... Blame Boeing for the fault, blame them for their wrongdoing.
It would be interesting to see statistics about airplane incidents with percentages divided between:
where the plane...
- had "minor" fault and the pilots did not manage to solve the problem (but they "should" or "could").
- had NO fault, but the pilots still crached the plane.
- had major fault (there was no way to save the plane by pilots).
- had "minor" fault but the pilots saved the day.
I don't have any number at hand, but I feel that the great majority of the accidents fell into the first two categories.
-
I wasn't surprised at what AvE found in his teardown of a Lockheed C130 AoA sensor. Nearly 50 years ago I scored a cockpit direction indicator for not very much that I found in a scrap bin at a local electronics retailer. Made by Smiths Industries, it had two resolvers a rotary damper and a two phase motor lots of gearing and generally mechanical porn. The damper was just a copper cylinder mounted on a shaft with a permanent magnet stator to generate eddy currents and the 3 phase brushed resolvers were built in the same way as in AvE's teardown. The AoA sensor in AvE's teardown would have been electrically, pressure, humidity and temperature tested and probably a lot more. Maybe some of the design parameters would have been tested during development and would be "guaranteed by design", like a bird strike for example. The aircraft industry have been using 3 phase 400Hz resolvers for what must be 80 years or more without any problems.
-
Don't fall into the same trap Boeing is exploiting - some old design or product must be safe because of very few or no incidents over many decades.
The problem with that mindset is any engineering changes bring you back to square one, where you have to evaluate their impact on safety, from scratch. Even though it has the legacy model number, or uses proven physics, that one change can make something unsafe.
Re-evaluating or doing a new safety assessment is time consuming and expensive so it's best to workaround it. This is a common management ploy to rush getting product to market.
Another method is to under-categorize the system change as nothing important, doesn't affect safety, the pilots should be able to handle it, kind of thinking.
You end up with a non-redundant (sensor) MCAS system that flies under the certification radar and avoids the full safety assessment it required.
We don't know the AoA sensor changes over the years, but what cost-improvements have been done to them?
Since 2004, over 200 reports of AoA sensor problems, much fewer for Boeing: FAA Service Difficulty Reporting (https://av-info.faa.gov/sdrx/Default.aspx)
Why are they malfunctioning so often? Cheapness? Killer birds hitting them?
Or an industry content to sit on it's ass and do nothing to improve the design and manufacturing.
If only 0.001% of the litigation dollars was instead spent on R&D towards better AoA sensors.
-
The pilots are the last line of defense.
Which is why you would want them to get all the training they can use and yet Boeing denied any training was necessary because this NEW plane handled just like the OLD plane. Which was a lie. A lie that cost lives.
-
MCAS assisted by faulty AOC caused 737 Brax to slide into river! Its awful! Pilots rescued plane and passengers! Hallelujah!
https://www.youtube.com/watch?v=NcPISBXRNlc (https://www.youtube.com/watch?v=NcPISBXRNlc)
-
I believe the plane in Florida was a regular Boeing 737 and not a 737 MAX. It seems it skidded along the runway and into the river so it was not anything to do with flight. It landed in a storm on a wet runway and could not stop in time.
-
MCAS assisted by faulty AOC caused 737 Brax to slide into river! Its awful! Pilots rescued plane and passengers! Hallelujah!
No, I can guarantee you that the aircraft in question did not fail because of MCAS, because it didn't have MCAS, since it's not a 737 MAX, since the FAA has not un-grounded the MAX yet.
-
MCAS assisted by faulty AOC caused 737 Brax to slide into river! Its awful! Pilots rescued plane and passengers! Hallelujah!
Trump?
-
MCAS assisted by faulty AOC caused 737 Brax to slide into river! Its awful! Pilots rescued plane and passengers! Hallelujah!
What a stupid thing to say. Shows you have NO understanding. Your credibility is now officially zero.
-
The "rat" look is sometimes what people want. Metal chips, coolant, oil, grease are messy. AvE's slang also seems to be part of a rough, unrefined approach contrasting the precise works that he's looking at. I've seen a few youtubers take on a persona to stand out.
That particular AoA sensor is primitive engineering by any means.
The slip-ring on the Litton resolver looks like something out of a cheap toy motor, with a bit of gold plating. Why isn't it brushless?
Open gears? Put them in a gearbox so any particles don't jam the sensor. How about a double seal on some bearings.
I bet the thing is worth a small fortune but reliability isn't there. Something is wrong with the Rosemount/UTC AoA sensors on the max.
ET302 suspected a bird hit it and broke off the vane but the engine intake is nearby with no fan damage? and the erroneous readings are not consistent with a broken vane.
how would you get power to the rotor without brushes? gearbox and bearing seals, why? it is a sealed unit
They have provably used the same sensor for 50 years with no issues
Brushless resolvers are the industry-wide standard these days, used in many many servo-motors, where absolute position sensing is required.
-
Boeing Knew About Safety-Alert Problem for a Year Before Telling FAA
-
Boeing Knew About Safety-Alert Problem for a Year Before Telling FAA
So if I'm reading that right the AOA disagree alert was supposed to be a standard feature that just didn't work? I'm having difficulty with that concept. Not because it isn't plausible, but the enormity of what that actually means. "We knew it didn't work correctly (or at all), but we let it slide". Surely that's erroneous.
-
Also reported by the BBC: https://www.bbc.co.uk/news/business-48174797 (https://www.bbc.co.uk/news/business-48174797)
Boeing has admitted that it knew about a problem with its 737 Max jets a year before the aircraft was involved in two fatal accidents, but took no action.
The firm said it had inadvertently made an alarm feature optional instead of standard, but insisted that this did not jeopardise flight safety.
How do you 'inadvertently' turn a standard feature into an extra cost ($80k/plane) option? :-//
EDIT: A case of 'please don't request this option, it doesn't work', or 'please fund us to make it work on your plane'(as an individual variation of the standard s/w)?
-
Is it possible the Flight Control Computer is out of memory?
Guessing it's some 80x86 redundant, fault-tolerant clunker that was not redesigned for the 737 max in the rush to compete with Airbus.
This is the only reason I can come up with that the AoA DISAGREE annunciator does not work, known over a year ago and no fix issued. Optional AoA gauge. And the old MCAS kindergarten-grade software.
I've seen what happens when legacy embedded computers get dragged along into new products.
The clock speed is too slow, not enough RAM or FLASH- so adding features becomes a minefield. You have to cut some to make room for others.
-
MCAS assisted by faulty AOC caused 737 Brax to slide into river! Its awful! Pilots rescued plane and passengers! Hallelujah!
No, I can guarantee you that the aircraft in question did not fail because of MCAS, because it didn't have MCAS, since it's not a 737 MAX, since the FAA has not un-grounded the MAX yet.
Tooki have been Honk Honk'ed!
-
has been what?
-
Has been Trolled seems to fit.
-
MCAS assisted by faulty AOC caused 737 Brax to slide into river! Its awful! Pilots rescued plane and passengers! Hallelujah!
https://www.youtube.com/watch?v=NcPISBXRNlc (https://www.youtube.com/watch?v=NcPISBXRNlc)
There are no 737 Max AC permitted to fly outside of Boeing and there testing program -- this was not a 737 Max AC and thus did not have the MCAS system -- troll somewhere else!
Brian
-
MCAS assisted by faulty AOC caused 737 Brax to slide into river! Its awful! Pilots rescued plane and passengers! Hallelujah!
No, I can guarantee you that the aircraft in question did not fail because of MCAS, because it didn't have MCAS, since it's not a 737 MAX, since the FAA has not un-grounded the MAX yet.
Tooki have been Honk Honk'ed!
WTF do neonazi memes have to do with your stupid statement?
-
A thread about plane crashes is sure to crash. Even in aviation and pilot forums, the discussions went nutty. We've all been exposed to lead and smoke.
Judge Andrew Napolitano on Fox News:
"... The failure to comply with a legal obligation to inform the carrier, the airline, of a defect in the software when that failure arguably resulted in death is the definition of criminally negligent homicide.”
-
U.S. pilots warned about the problem long before the crashes.
U.S. pilots warned about Boeing 737 MAX 8 concerns in months leading up to Ethiopia crash
https://globalnews.ca/news/5055894/u-s-pilots-warned-boeing-737-max-8-ethiopia-crash/
-
Is it possible the Flight Control Computer is out of memory?
Guessing it's some 80x86 redundant, fault-tolerant clunker that was not redesigned for the 737 max in the rush to compete with Airbus.
This is the only reason I can come up with that the AoA DISAGREE annunciator does not work, known over a year ago and no fix issued. Optional AoA gauge. And the old MCAS kindergarten-grade software.
I've seen what happens when legacy embedded computers get dragged along into new products.
The clock speed is too slow, not enough RAM or FLASH- so adding features becomes a minefield. You have to cut some to make room for others.
I've seen some reaching in my time - but that's a whole new level...... :palm:
-
I'm just asking if the problem is not entirely corruption and criminal negligence, and has some engineering basis due to a hardware limitation.
Avionics computers are a decade behind electronics technology, due to the slow development cycle. MTBF, redundancy, fault-tolerance, testing to avionics standards is a huge burden and cost.
777 Primary Flight Computer is three dissimilar CPUs 80486, AMD29050, MC68040. Antiques now.
The 737 max 8 FCC seems to be Rockwell Collins 822-1604-151 which dates it back to 2002, when it replaced the Honeywell FCC.
Let's add bigger screens, move nav, and MCAS to a new aircraft with an old carry-over computer.
Otherwise, how can Boeing bungle implementing an AoA discrepancy annunciator, then sit on it for over a year? :-//
-
I'm just asking if the problem is not entirely corruption and criminal negligence, and has some engineering basis due to a hardware limitation.
Read the thread because it has been discussed and there are links to many articles. Boeing needed a new airplane to remain competitive with Airbus and did not have the time to develop such airplane so they came up with the brilliant idea of "upgrading" the 737 even though the "upgrade" was a major redesign of the frame because the engines needed to be moved forward and up. This affected the flight characteristics but they thought they could "hide" this from the pilots with the MCAS system. Recertification of airplane and pilots would have cost time and money they did not have.
A lot of people dropped the ball, both in Boeing and in the FAA.
So, no, no engineering basis, all human "error" (greed).
-
Turkish Airlines flight 1951 (https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1951) 737-800 crash in 2009, 9 killed.
Of two radio altimeters, Boeing's software relied on a single sensor for the autothrottle computer, and during landing it shut engines down to idle prematurely :palm:
They've learned absolutely nothing. This company is rotten to the core.
Boeing failed to apply safety lesson from deadly 2009 crash (https://www.seattlepi.com/business/article/Boeing-failed-to-apply-safety-lesson-from-deadly-13825891.php)
-
They've learned absolutely nothing. This company is rotten to the core.
Boeing failed to apply safety lesson from deadly 2009 crash (https://www.seattlepi.com/business/article/Boeing-failed-to-apply-safety-lesson-from-deadly-13825891.php)
That link is blocked in Europe and I had to use a VPN to see it:
The company said that it knew months before the Lion Air crash that a cockpit alert -- suggesting an angle-of-attack sensor may be malfunctioning -- wasn't working the way the company had told buyers of the jetliner. But it didn't share its findings with airlines or the FAA until after that plane went down off the coast of Indonesia.
Boeing's latest admission raised new questions about the 737 Max's development and testing - and the company's lack of transparency.
One reason for adding multiple sensors to aircraft is they can and do fail.
Pilots have for decades relied on the weather-vane-like angle-of-attack sensors to warn them when they near a dangerous aerodynamic stall.
-
https://www.youtube.com/watch?v=0eT9XakALwU (https://www.youtube.com/watch?v=0eT9XakALwU)
https://www.youtube.com/watch?v=QytfYyHmxtc (https://www.youtube.com/watch?v=QytfYyHmxtc)
-
Which vid is Blanco referring to? There are at least 3!
https://www.youtube.com/watch?v=oJYX58vJ42k (https://www.youtube.com/watch?v=oJYX58vJ42k)
-
That's happening irrespective of anything you're trying to do.
That's just happened whether you like it or not.
MCAS had malfunctioned and allowed the pilots five seconds intervals to regain control.
LOL. Who still watches TV? Who still believes a single word of the mainstream media? Only idiots...
An experienced pilot would have thought: "This damn thing wants to kill me, it's trimming nose down relentlessly again and again" and proceed to do whatever it takes to avoid that happening. There's a plethora of things that could have been done:
1) Grab and stop the trim wheel, by hand, yes, by hand Mr. playstation pilot, use the primitive human mechanical brute force because your life depends on it. 2) Push nose up on the trim button on the yoke (overrides MCAS). 3) Put the flaps in position 1 (disables MCAS). 4) untrim manually. 5) Flip the stabilizer trim power cutout switch. And perhaps some more that IDK because I'm not a pilot.
-
Libertarian Judge Napolitano on the juridical aspects of Boing behavior!
https://www.youtube.com/watch?v=QTgsapUmKaI (https://www.youtube.com/watch?v=QTgsapUmKaI)
-
Wallstreet Journal about Boing and FAA relationship.
https://www.youtube.com/watch?v=qifT9MBZm0k (https://www.youtube.com/watch?v=qifT9MBZm0k)
-
Boeing Altered Switches that might have saved Ethiopian Air.
https://www.heraldnet.com/business/boeing-altered-key-switches-in-737-max-cockpit/ (https://www.heraldnet.com/business/boeing-altered-key-switches-in-737-max-cockpit/)
-
^If Boeing's viewpoint is true, that there is no condition where a pilot should ever flip only one switch, then there could either be a single ganged switch* or there could be a physical bar that connects both switches during flight (which can be removed in case there's any condition where a mechanic/tech might need to flip just one).
*Or in this case, it appears they are both doing the same thing, anyway. So you could just remove one of them.
If the goal is to simplify the pilot's life, giving him two switches that secretly operate like an "and" (or an ior, depending on which direction you define the logic) and telling him that "under condition X, Y or Z flip both switches" is a bit obfuscating. Enough switches in the cockpit already without doing this. And leaving the end-user with these kinds of little loose ends and red herrings can build up into a problem. But in this case there was maybe some red tape in the way of doing the obvious. And deadlines.
Why not leave the ability to switch off just the FCC inputs? Perhaps they did not want to allow the plane to be flown with MCAS disabled, because the aerodynamic issue is pretty serious. So they turned it into an all or nothing, only to be cut in a serious emergency where subsequently accidentally stalling the plane is a relative minor consequence and acceptable risk.
This switch change is further evidence of where Boeing's main concerns were. They gave MCAS a huge authority/response. They changed the switches to prevent disabling of MCAS. Preempting/avoiding an aerodynamic stall was evidently the major concern. They made the change, because they thought it made the plane safer. And perhaps they were correct. If a 737 pilot can't even bring himself to press the trim up button for more than a few seconds when the plane is drying to nose into the dirt, I find it unlikely a pilot is going to immediately trim down for 9+ seconds if and when he/she were to ever get the plane into a severely high AOA. This is like expecting the captain of the Titanic to be able to slalom through traffic cones by making decisive and extreme course corrections that manifest in the proper behavior 2 minutes into the future.
-
Why not leave the ability to switch off just the FCC inputs?
While I do understand your point (and it would seem like a good idea) this is where you would enter into the "new type" situation. The cutoff switches were meant to kill the stabilser trim motor for any and all reasons. There was no intent to define WHAT conditions caused the unwanted stabliser trim action - just that, if it happened (for whatever reason) the pilots had a means to halt it.
Change the functionality of these switches and you add a whole new chapter in the operation of the aircraft. Just because you think such a change is a minor one, does not mean you are right. For example, say you did change these switches to disconnect from computerised control - and then there was a short in the driver circuitry for the stabliser trim motor. Your "cut out" switches don't cut power any more ... the stabilser goes full travel and the only thing you can do is put your head between your legs and kiss your arse goodbye.
Such differences in operation are the sort of thing that lead to a new type rating requirement if there's enough of them. This can happen if there are a sufficient number of "almost negligible" changes, which is why the passenger "No smoking" sign switch still exists in the cockpit of the 737, even though it's not been needed for decades.
-
While I do understand your point (and it would seem like a good idea) this is where you would enter into the "new type" situation. The cutoff switches were meant to kill the stabilser trim motor for any and all reasons. There was no intent to define WHAT conditions caused the unwanted stabliser trim action - just that, if it happened (for whatever reason) the pilots had a means to halt it.
But if the article is correct, that is exactly what Boeing *did*.
But as Boeing was transitioning from its 737 NG model to the 737 MAX, the company altered the labeling and the purpose of those two switches. The functionality of the switches became more restrictive on the MAX than on previous models, closing out an option that could conceivably have helped the pilots in the Ethiopian Airlines flight regain control.
Prior to the Max the two switches had different roles :
The Seattle Times found that the left switch on the 737 NG model is capable of deactivating the buttons on the yoke that pilots regularly press with their thumb to control the horizontal stabilizer. The right switch on the 737 NG was labeled “AUTO PILOT” and is capable of deactivating just the automated controls of the stabilizer.
Which is explains the quote you quoted :
Why not leave the ability to switch off just the FCC inputs?
-
The cutout switches, electric trim operating differently between 737 models is another Boeing design flaw.
They must have contracted Clown Co. to do the design. The basics of user-interface design: keep it simple, keep it consistent.
This is anything but a "blame the pilots" for yet another unnecessary complicated memory item.
"uncommanded movement of the {737} aircraft's rudder". (https://en.wikipedia.org/wiki/Boeing_737_rudder_issues) It was the same actuator valve as the elevator... so much for hydraulics being reliable.
"Testing revealed that under certain circumstances, the PCU's dual servo valve could jam and deflect the rudder in the opposite direction of the pilots' input. Thermal shock testing revealed that the uncommanded rudder movement could be replicated by injecting a cold PCU with hot hydraulic fluid. Thermal shock resulted in the servo's secondary slide becoming jammed against the servo housing, and that when the secondary slide was jammed the primary slide could move to a position that resulted in rudder movement opposite of the pilot's commands."
I wonder if other systems (elevator) flight control design was changed as a result of these incidents.
Too bad Boeing fired all the senior engineers that remembered this stuff.
-
^Scary. The plane doing the opposite of what is required and in a way that leaves the plane to nose dive, plus this happens for a control that is mostly used when landing!!! There were quite a lot of fatal accidents and close calls attributed to that. I guess the timing of these MAX accidents and the perceived 'shadiness' is what makes it such a bigger deal?
The Seattle Times found that the left switch on the 737 NG model is capable of deactivating the buttons on the yoke that pilots regularly press with their thumb to control the horizontal stabilizer. The right switch on the 737 NG was labeled “AUTO PILOT” and is capable of deactivating just the automated controls of the stabilizer.
Yep. I wonder if they got this right. I think the "master" (left) switch should probably kill the motor, completely. But I suppose it might just disconnect the pilots' controls, in case of a button/switch fault, so that the autopilot can still be used? And the other switch USED to enable/disable just the FCC/autopilot control over the motor. If I understand the article, correctly, both switches now cut all motorized trim movement. 00, 01, 10 all mean the motor is disabled. 11 = motors enabled and accessible to pilot manual trim button, autopilot, and MCAS. It's funny that they can't remove a switch due to red tape, but they can apparently rename it?
In any emergency, it seems you never do anything but cut both switches, so it shouldn't have any immediate effect on an emergency. But it means that after stabilization, a fault of any of these 3 controls means you can't re-enable any of the others after, say, further troubleshooting and/or call with maintenance crew. But I agree with the Times that if the pilots had the ability to flip off just MCAS/autopilot control and leave the manual trim buttons intact, and they knew this was available, that ET302 esp might have been ok. I think I posted something to that effect a week ago. These pilots apparently knew what they were doing when flipping stab trim back on, but maybe weren't prepared for the immediacy/scale of the MCAS response or the enormity of how much manual trim they really needed to apply, in addition to allowing the plane get too fast for the condition and not knowing or anticipating the effect that had on trim and elevator control of the plane. It sure seems like they were trying to fix the trim with the wheel and would surely have enabled only the manual trim control buttons if they had and were aware of that option. They had at that point realized there was a left alpha vane malfunction.
One thing that seems obvious in hindsight is some sort of notification when MCAS is activated. It might have just gotten lost in the other noise, stick shakers, clacker alerts, ground proximity warnings. But it is evident that when a plane is crashing, pilots don't necessarily look straight down between the seats. I imagine if they even heard/noticed the trim moving, they both thought the other pilot was trimming UP. If they had been aware, I bet even GoJ's "Playstation pilot" takes some corrective action, hopefully in time.
"uncommanded movement of the {737} aircraft's rudder". It was the same actuator valve as the elevator... so much for hydraulics being reliable.
Wonder if the extreme control surface forces/pressures in these accidents might be revealing some new, still unknown fault in the hydraulics?
Totally unrelated one of the strangest accidents I have come across. The ghost flight.
5 seconds too late, maintenance guy, "oh, yeah. Hey, can you check that switch I might have forgotten to flip back?"
Everyone in the plane puts on an oxygen mask except the pilots?
Autopilot continues doing its thing, ascending to 40,000 feet, even when the cabin has no pressure?
Flight attendant wakes up and is actually a pilot. But the fuel runs out 10 seconds, later?
-
https://www.youtube.com/watch?v=PQLT9GLDYt0 (https://www.youtube.com/watch?v=PQLT9GLDYt0)
-
Totally unrelated one of the strangest accidents I have come across. The ghost flight.
5 seconds too late, maintenance guy, "oh, yeah. Hey, can you check that switch I might have forgotten to flip back?"
Everyone in the plane puts on an oxygen mask except the pilots?
Autopilot continues doing its thing, ascending to 40,000 feet, even when the cabin has no pressure?
Flight attendant wakes up and is actually a pilot. But the fuel runs out 10 seconds, later?
afair the outcome of the investigation was to change the checklist for missing cabin pressure, putting "Put on oxygen masks!" as the first item so the pilots don't pass out while debugging the problem
-
It’s sad to see some congressmen and the FAA chief himself are in Boeing payroll after watching this part of video.
Its no secret for decades, the collusion & corruption level in there at the whole either country/legislative/executive, is comparable to those less developed world like in Africa or South America.
-
The engineering profession is continuing to get worse due to corporation's priority #1 being profit with the ensuing corruption :(
The former 737 max engineers basically confirming they laid off the experienced/management-bucking engineers, and flogged the remaining ones to meet cost and time targets.
“It was pretty intense low morale because of all the layoffs—constant, grinding layoffs, year after year".
"Boeing has reshaped its workforce in an all-consuming focus on shareholder value."
'The relentless message: Shareholders would henceforth come first at Boeing. The important thing was not to get “overly focused on the box,” [CFO] Hopkins said in a 2000 interview with Bloomberg. “The box”—the plane itself—“is obviously important, but customers are assuming the box is of great quality.” This was heresy to engineers, to whom the box was everything. The strike that year was formally over wages and benefits, but workers described it as a referendum on management.'
"Adam Dickson, a manager of fuel systems engineering for the 737 Max, retired in November after almost 30 years at Boeing—in part, he says, because of dismay over performance targets that risked sacrificing safety for profits. “It was engineering that would have to bend,” he says. The company’s priorities were expressed in annual performance reviews in which engineers were measured in part on how much their designs had cost."
Former Boeing Engineers Say Relentless Cost-Cutting Sacrificed Safety (https://www.bloomberg.com/news/features/2019-05-09/former-boeing-engineers-say-relentless-cost-cutting-sacrificed-safety)
-
The engineering profession is continuing to get worse due to corporation's priority #1 being profit with the ensuing corruption :(
This investigation video was made in 2014 ... 5 years ago.
Its produced by Al Jazeera, yes, I know & aware, some people here I believe will not trust this news agency.
And yes, in that video already pointed out that FAA already "delegated" it's authority to approve safety matter to Boeing for it's own certification, long ... long time ago.
PS : If you're bored, suggest to jump to about 42:00 and watch for just 5 minutes, to see some funny stunts by their top executive, which was a VP + GM grade executive, and he was trashed and bullied publicly by "higher" authority, in front of the news crews and few Boeing staffs, and its recorded. :-DD >:D
https://youtu.be/rvkEpstd9os
-
(https://static.seattletimes.com/wp-content/uploads/2019/05/Boeing-Wall-Street-ONLINE-COLOR-768x511.jpg)
-
A reasonable summary for people wanting to catch up...
https://www.bbc.co.uk/news/resources/idt-sh/boeing_two_deadly_crashes (https://www.bbc.co.uk/news/resources/idt-sh/boeing_two_deadly_crashes)
-
The engineering profession is continuing to get worse due to corporation's priority #1 being profit with the ensuing corruption :(
The former 737 max engineers basically confirming they laid off the experienced/management-bucking engineers, and flogged the remaining ones to meet cost and time targets.
IME, modern management seems to enjoy repeating buzzwords as if they have magical powers. They view successful exertion of their will as a success, regardless of the wisdom or result of the outcome. They like to take credit when they get lucky and ignore the failures they created despite engineers knowing (not guessing, not hedging) that they are making an irrefutable mistake. When an engineer attempts to explain reality to management, all that happens is their eyes glaze over. I've watched people set fire to millions of dollars despite being explained exactly how they were setting fire to millions of dollars.
It seems like people can't believe it when someone who makes less $$ than them actually understands things that they don't. When you're not able to understand something, I guess it's hard to figure out who to believe, and maybe this person sometimes just plug their ears and closes their eyes and... chooses to believe the outcome that will make them the most profit will somehow become reality.
I would not be surprised if Boeing engineers knew there were flaws and voiced their concerns/protests and were simply ignored.
-
Boeing admits 737 Max sims didn't accurately reproduce what flying without MCAS was like
https://www.theregister.co.uk/2019/05/20/737_max_flight_simulators_not_accurate_report/ (https://www.theregister.co.uk/2019/05/20/737_max_flight_simulators_not_accurate_report/)
-
Boeing Official Played Down Scenario That May Have Doomed Ethiopian Jet - WSJ
-
https://www.youtube.com/watch?v=n4qDLR4s45U (https://www.youtube.com/watch?v=n4qDLR4s45U)
-
Now a ""truly"" redundant system?! Oh, the days of rollacosta maneuver!
-
The engineering profession is continuing to get worse due to corporation's priority #1 being profit with the ensuing corruption :(
The former 737 max engineers basically confirming they laid off the experienced/management-bucking engineers, and flogged the remaining ones to meet cost and time targets.
IME, modern management seems to enjoy repeating buzzwords as if they have magical powers. They view successful exertion of their will as a success, regardless of the wisdom or result of the outcome. They like to take credit when they get lucky and ignore the failures they created despite engineers knowing (not guessing, not hedging) that they are making an irrefutable mistake. When an engineer attempts to explain reality to management, all that happens is their eyes glaze over. I've watched people set fire to millions of dollars despite being explained exactly how they were setting fire to millions of dollars.
It seems like people can't believe it when someone who makes less $$ than them actually understands things that they don't. When you're not able to understand something, I guess it's hard to figure out who to believe, and maybe this person sometimes just plug their ears and closes their eyes and... chooses to believe the outcome that will make them the most profit will somehow become reality.
I would not be surprised if Boeing engineers knew there were flaws and voiced their concerns/protests and were simply ignored.
In the mid 80's, when I worked at IBM, they had a major push for quality in a program wrapped around the 6-sigma thing. We were all called to large presentations and schooled on the importance of quality and to commemorate the program they handed out Cross Pens with IBM Six-Sigma on it. Over the next few months virtually all the pocket clips for the pens broke off -- they'd purchased cheap knock-offs. I would tell you how funny that was but even then I knew there was nothing funny about it. Bean counters have been in control for decades and to Wall Street that's just fine -- you can still make money in a company going south so long as cost are going south faster than income. And hey, once a company has screwed the pooch you put your money elsewhere. Workers ... pffft
Brian
-
It looks as if they've found another (cpu capacity?) problem now that they have pilots using the 737 Max simulator...
Boeing suffers new 737 Max issue that could delay return
....
Reuters, which first reported the new issue, said during an FAA pilot simulation in which the stall-prevention system was activated, it had taken longer than expected to recover the aircraft.
Other sources said the problem was linked to the aircraft's computing power and whether the processor possessed enough capacity to keep up.
Boeing said "we are working closely with the FAA to safely return the Max to service" and that it believed a software fix would address the problem.
But the FAA will be looking into whether it is a hardware issue.
It's a shame they didn't have pilot simulator training in place before the crashes. :(
https://www.bbc.co.uk/news/business-48752932 (https://www.bbc.co.uk/news/business-48752932)
EDIT: Second thread already started here: https://www.eevblog.com/forum/chat/another-deadly-737-max-control-bug-just-found!/ (https://www.eevblog.com/forum/chat/another-deadly-737-max-control-bug-just-found!/)
-
It looks as if they've found another (cpu capacity?) problem now that they have pilots using the 737 Max simulator...
Boeing suffers new 737 Max issue that could delay return
....
Reuters, which first reported the new issue, said during an FAA pilot simulation in which the stall-prevention system was activated, it had taken longer than expected to recover the aircraft.
Other sources said the problem was linked to the aircraft's computing power and whether the processor possessed enough capacity to keep up.
Boeing said "we are working closely with the FAA to safely return the Max to service" and that it believed a software fix would address the problem.
But the FAA will be looking into whether it is a hardware issue.
It's a shame they didn't have pilot simulator training in place before the crashes. :(
https://www.bbc.co.uk/news/business-48752932 (https://www.bbc.co.uk/news/business-48752932)
EDIT: Second thread already started here: https://www.eevblog.com/forum/chat/another-deadly-737-max-control-bug-just-found!/ (https://www.eevblog.com/forum/chat/another-deadly-737-max-control-bug-just-found!/)
Despite the headlines, this story boils down to: The proposed software changes didn't pass testing, and more changes are needed. This "new problem" was never in service, so nobody was put at risk. In other words, the testing and verification system worked properly in this case!
Which means this is actually a positive story from the safety perspective. From the financial point of view it's not so good, since this causes a delay in returning planes to service.
-
Yeah but facts aren’t good as clickbait link titles!!!
-
https://www.youtube.com/watch?v=isy9yAU6ajQ (https://www.youtube.com/watch?v=isy9yAU6ajQ)
-
That guy just regurgitates second hand news, he's non-technical and I have to laugh- the term "microprocessor failure" and people not knowing if that's a software error, hardware problem, algorithm error etc. Each has huge differences and consequences.
It's Boeing's fault for sticking their head in the sand and not issuing press statements other than "at least 3 months to fix" to keep investors informed of this new problem.
-
Despite the headlines, this story boils down to: The proposed software changes didn't pass testing, and more changes are needed. This "new problem" was never in service, so nobody was put at risk. In other words, the testing and verification system worked properly in this case!
Which means this is actually a positive story from the safety perspective. From the financial point of view it's not so good, since this causes a delay in returning planes to service.
This problem has existed all along and still exist on all 737 max planes.
https://www.wsj.com/articles/faa-finds-new-software-problem-in-boeings-737-max-11561596917 (https://www.wsj.com/articles/faa-finds-new-software-problem-in-boeings-737-max-11561596917)
"The software issue involves an emergency procedure that would be used to counteract MCAS if it malfunctions, erroneously pushing the plane’s nose down, according to the people familiar with the matter. The FAA identified the problem last week during simulator tests, these people said, after an agency test pilot determined that the procedure took more time than was acceptable to execute.
The new problem is related to software that was original to the aircraft, not revisions in conjunction with changes to MCAS that were made after two fatal crashes of 737 MAX jets, according to one of the people familiar with the matter."
-
Despite the headlines, this story boils down to: The proposed software changes didn't pass testing, and more changes are needed. This "new problem" was never in service, so nobody was put at risk. In other words, the testing and verification system worked properly in this case!
Which means this is actually a positive story from the safety perspective. From the financial point of view it's not so good, since this causes a delay in returning planes to service.
This problem has existed all along and still exist on all 737 max planes.
https://www.wsj.com/articles/faa-finds-new-software-problem-in-boeings-737-max-11561596917 (https://www.wsj.com/articles/faa-finds-new-software-problem-in-boeings-737-max-11561596917)
"The software issue involves an emergency procedure that would be used to counteract MCAS if it malfunctions, erroneously pushing the plane’s nose down, according to the people familiar with the matter. The FAA identified the problem last week during simulator tests, these people said, after an agency test pilot determined that the procedure took more time than was acceptable to execute.
The new problem is related to software that was original to the aircraft, not revisions in conjunction with changes to MCAS that were made after two fatal crashes of 737 MAX jets, according to one of the people familiar with the matter."
I guess that could mean it also affects the 737NG in the case of runaway trim
-
https://www.youtube.com/watch?v=PQLT9GLDYt0 (https://www.youtube.com/watch?v=PQLT9GLDYt0)
Please provide some context when posting links or videos. I have no idea why this video is relevant or one should invest 15 minutes into it.
-
I'm not sure this one has been posted yet, but it provides a decent summary of what went wrong for what reasons and why Boeing's decision to withhold information about the MCAS system was so malicious. It's hard to imagine the lost trust being regained anytime soon.
https://m.youtube.com/watch?v=H2tuKiiznsY
-
...and why Boeing's decision to withhold information about the MCAS system was so malicious.
You could call it duplicitous, negligent, reckless, unethical, and irresponsible (just for starters), but it certainly wasn't malicious. (Malicious means specifically "with the intent to cause harm", and that certainly was not the case. Harm was caused, but since harm was not the intent, it is by definition not malice.)
-
"March 30, 2016, Mark Forkner, the Max’s chief technical pilot, sent an email to senior F.A.A. officials... Would it be O.K. to remove MCAS from the pilot’s manual?". (https://www.nytimes.com/2019/06/01/business/boeing-737-max-crash.html)
Forkner worked for Boeing but was a former F.A.A. employee and looked after F.A.A. related issues...
It's a pretty long read how MCAS came about, after test pilots complained about aircraft's handling and then Boeing hid it so no pilot simulator-training would be required. I think they only have a few 737 max flight simulators in North America. Even worse is Boeing moved to the term "technical pilot" who are no longer active pilots, yet working on the project. MCAS wasn't even part of the flight sim's software. It's systemic corruption across the board.
Negligent homicide or involuntary manslaughter might be a better term.
-
But MCAS (the Maneuvering Characteristics Augmentation System) per se is not the problem, the problem is whatever it is that makes it (mal) function not-as-intended, be it the sensors, the circuitry associated with the sensors, or a bug à la toyota in the software.
-
Surely if its design relies on too little (no?) sensor redundancy, then it is the problem.
-
Then the problem of the toyotas was that they had an accelerator pedal... ??
-
Maybe if it had an accelerator pedal with a single sensor, then yes. Aircraft redundancy rules on critical systems are rather different from automotive though.
EDIT: I think this is very much old ground though.
-
It is the reliance on a single sensor, and the antique flight control computer seems to be overrun now.
Apparently it was 50% utilization in the early 1990's and after STS and MCAS and other new features, the processor can't keep up and reboots while you are in a dive. This was the latest FAA gripe.
-
I doubt the problem was the AoA sensor because both were new/just replaced in the Lion Air 610 flight crash. It would seem they only fail so often in these MAX 8 planes... strange! Looks to me like if it were something else along the path from the sensor to the data in the program that results in a bad/corrupted value in AoA variable the program sees. A bug à la toyota, so to speak.
-
Saudi Arabian airline Flyadeal have just cancelled an order for 30 Boeing 737 MAX aircraft. The deal, which included an additional option to purchase 20 more 737 Max aircraft, was worth $5.9bn. The ailine will now operate Airbus A320's.
[/url]https://www.bbc.co.uk/news/business-48899588 (https://www.bbc.co.uk/news/business-48899588)[/url]
-
It was said (original) MCAS toggled between using the left or right AoA sensor, every flight. That would be another clown algorithm that could have confused the maintenance crew as to which sensor was malfunctioning. Imagine charging $80,000 for the AoA DISAGREE annunciator option which didn't even work.
At least the AoA sensors are on the list somewhere with the European regulator:
"EASA’s checklist includes a number of issues that have been disclosed: the potential difficulty pilots have in turning the jet’s manual trim wheel, the unreliability of the Max’s angle of attack sensors, inadequate training procedures, and a software issue flagged just last week by the FAA pertaining to a lagging microprocessor. But the agency also listed a previously unreported concern: the autopilot failing to disengage in certain emergencies."
https://www.bloomberg.com/news/articles/2019-07-05/europe-sets-out-demands-for-boeing-before-max-can-fly-again (https://www.bloomberg.com/news/articles/2019-07-05/europe-sets-out-demands-for-boeing-before-max-can-fly-again)
I have no idea what the new autopilot problem is about.
-
MCAS toggled between both AoA sensors before each flight? Wow, those 9$ programmers really wanted to retaliate for their bad salary...
I can imagine how the MCAS software got bloated up so much that it would slow down the computers it runs on: model based design. Drag and hack together the control system in Matlab/Simulink and then use the auto-generated code. I don't know if Boeing does this on their civil airliners, but it is a trend in the industry.
-
MCAS toggled between both AoA sensors before each flight? Wow, those 9$ programmers really wanted to retaliate for their bad salary...
This is pretty stupid, yeah. Doing it like this means that the more sensors you have, the more the chance of a malfunction. If MTF is 100,000 flights, then 1 sensor might be good for 10,000-1,000,000 flights. 2 sensors, and the MTF that 1 of them will fail will decrease.
You could have 100 sensors, and it means that if 99 of them are good, you're eventually gonna crash the plane.
This is essentially using a $100 million plane and 100+ souls as an AOA sensor tester.
I doubt this has anything to do with the $9/hr coders, though. They would surely not be in charge of designing the algorithm. You don't ask a coder to design an airplane anti-stall system, do you? You pay them to implement it to w/e specs your team of airplane engineers and test pilots and/or the FAA have deemed best/necessary, right? And $9.00 an hour is probably a pretty good wage in India. So it was 99.9% white guys that fucked this up.
-
Found the source:
"Since MCAS is an FCC function, the AoA source for MCAS is that of the FCC in use; ie FCC 1 uses the Captains AoA probe and FCC 2 uses the F/Os AoA probe. When the 737 is powered up the FCC used is FCC 1 for that flight, this changes for each subsequent flight until the aircraft is powered down. Therefore the AOA sensor that is used for MCAS changes with each flight post power-up." http://www.b737.org.uk/mcas.htm#aoa (http://www.b737.org.uk/mcas.htm#aoa)
"... it [MCAS] starts on the left, then alternates between left and right on each flight." Reuters
So, after a cold-boot MCAS is going to use the left AoA sensor. Russian roulette has better odds.
In JT043 (and previous flight), JT610, ET302 it was the left AoA sensor that had problems. It's strange, almost as if the left resolver-to-digital has issues.
After JT043, the left (Captain's) AoA sensor had errors and apparently was replaced by a refurb, sensor came from a repair shop in Florida, XTRA Aerospace Inc. (https://www.bloomberg.com/news/articles/2019-04-02/faulty-737-sensor-from-lion-air-crash-linked-to-u-s-repair-shop)
Bloomberg seems to sensationalize the stories and not correct conflicts, earlier saying the sensor was not actually repaired/replaced, just a reboot to clear trouble codes.
-
Then the problem of the toyotas was that they had an accelerator pedal... ??
This is a bit off-topic, but people get that wrong a lot...
The problem with the Toyotas was that they had no kill switch or other emergency bypass.
With any other vehicle, there is always a way to kill and/or disengage the engine from the rest of the drive train- and almost always both. Simply depress the clutch (or put it into neutral in an automatic or manual) or turn the physical key off- two emergency solutions. Hell, even on cheap dirt bikes and kids' go-karts there are kill switches and/or dead-man switches. In that 'keyless' model of Toyota, there was neither way to physically turn the engine off nor disengage the engine from the rest of the drive drain in the event of a runaway engine. For some reason, the engineers decided to lock the engine and drive train while throttle was being depressed- making it impossible to physically force it out of gear. There was no emergency cutoff to kill the engine at all, or any other way to kill the engine or stop the vehicle. In competing models from other brands, there are ways to disengage the engine under load. The engine might die, but you won't.
There was some marketing scapegoat BS they shoveled out about some stupid "floor mat", but that is irrelevant (if it was true at all). If the vehicle had standard safety capabilities (such as those mentioned above), that family would still be alive. There are a lot of causes for an engine to lock at full throttle, but there is no excuse to remove any way to safely deal with that problem when it comes up. Toyota got cocky by removing those critical safety features and it backfired hard. Then they deflected the blame to the innocent deceased police officer (the driver). Toyota can suck a fat one.
/rant
-
Then the problem of the toyotas was that they had an accelerator pedal... ??
This is a bit off-topic, but people get that wrong a lot...
The problem with the Toyotas was that they had no kill switch or other emergency bypass.
With any other vehicle, there is always a way to kill and/or disengage the engine from the rest of the drive train- and almost always both. Simply depress the clutch (or put it into neutral in an automatic or manual) or turn the physical key off- two emergency solutions. Hell, even on cheap dirt bikes and kids' go-karts there are kill switches and/or dead-man switches. In that 'keyless' model of Toyota, there was neither way to physically turn the engine off nor disengage the engine from the rest of the drive drain in the event of a runaway engine. For some reason, the engineers decided to lock the engine and drive train while throttle was being depressed- making it impossible to physically force it out of gear. There was no emergency cutoff to kill the engine at all, or any other way to kill the engine or stop the vehicle. In competing models from other brands, there are ways to disengage the engine under load. The engine might die, but you won't.
There was some marketing scapegoat BS they shoveled out about some stupid "floor mat", but that is irrelevant (if it was true at all). If the vehicle had standard safety capabilities (such as those mentioned above), that family would still be alive. There are a lot of causes for an engine to lock at full throttle, but there is no excuse to remove any way to safely deal with that problem when it comes up. Toyota got cocky by removing those critical safety features and it backfired hard. Then they deflected the blame to the innocent deceased police officer (the driver). Toyota can suck a fat one.
/rant
Yes throttle sticking is nothing new and can happen to any engine/vehicle, I had that happen to me back in the mid 70's with a MK2 Jaguar the cable jammed with the throttle half open in the centre of Cambridge while in 2nd gear I was up to nearly 60MPH before I turned the ignition switch off. So kill switches are an imperative at all times.
-
FAA let Boing sign their own safety certs! :popcorn:
https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max (https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max)
https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html (https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html)
-
Reverse Monty hall.
-
FAA let Boing sign their own safety certs! :popcorn:
https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max (https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max)
https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html (https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html)
A double-edged sword. That would also hand off all responsibility to Boeing.
I bet it's not going to end up very pretty.
-
FAA let Boing sign their own safety certs! :popcorn:
https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max (https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max)
https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html (https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html)
Hows that being the news? This was known from day 1. :-//
-
FAA let Boing sign their own safety certs! :popcorn:
https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max (https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max)
https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html (https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html)
Hows that being the news? This was known from day 1. :-//
No idea , maybe MSM after all just ""fake news""? :-// ... :popcorn:
-
FAA let Boing sign their own safety certs! :popcorn:
https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max (https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max)
https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html (https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html)
De-regulation has been a major thing for 4 decades and this is the logical consequence of this mindset. The FAA has been impeded in there regulatory efforts by a combination of this push to de-regulate and the controls on there purse strings that limit the number of people that might otherwise investigate and test things. When you have too few people it makes sense to outsource this testing and regulatory work and who better to do that then the people designing and building the planes -- I mean, who know the system better than them. So, the long-term consequence of this de-regulation mania is that we put the fox in the hen house with predictable results.
Brian
-
But MCAS (the Maneuvering Characteristics Augmentation System) per se is not the problem, the problem is whatever it is that makes it (mal) function not-as-intended, be it the sensors, the circuitry associated with the sensors, or a bug à la toyota in the software.
partially agree..
As a side note: to keep nose within a certain angle tolerance, the system obeys the PID controller rules.
There's a complex issue there, I guess;
-unknown external factor(s) which is just swinging that system based on PID controller rules (here could be many sub-items)
- attack angle sensor is OK, however, in certain conditions its signal cannot be processed properly by system (air flow whirl at place where sensor(s) mounted, micro/macro swinging of fuselage or whatever)
- attack angle sensor is NOK, low reliability
- PID controller is not capable to process exceeding certain limits incoming values, due to wrong coefficient settings or so;
- it is not possible in principle to design an appropriate PID system, due to exceeding all limits external factors (e.g. much unbalanced fuselage)
-missing of elementary redundancy (that not the case, I think, it's aviation);
-influence redundand control channels on each other, somehow (code, conception mistake);
-a lack of option to override that system (code, conception mistake);
-no docs and corresponding training program on that system behaving and misbehaving;
BR
Generally speaking, the PID regulation rules it's foundation of automation based on 'higher mathematics' and constant head ache by students.
-
FAA let Boing sign their own safety certs! :popcorn:
https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max (https://www.zerohedge.com/news/2019-07-27/faa-let-boeing-sign-its-own-safety-certifications-737-max)
https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html (https://www.nytimes.com/2019/07/27/business/boeing-737-max-faa.html)
De-regulation has been a major thing for 4 decades and this is the logical consequence of this mindset. The FAA has been impeded in there regulatory efforts by a combination of this push to de-regulate and the controls on there purse strings that limit the number of people that might otherwise investigate and test things. When you have too few people it makes sense to outsource this testing and regulatory work and who better to do that then the people designing and building the planes -- I mean, who know the system better than them. So, the long-term consequence of this de-regulation mania is that we put the fox in the hen house with predictable results.
Brian
Sorry, don't mean to derail, its just can't help it to think about "other" safety/regulatory bodies that are in charge for simpler daily stuffs, say like ... food safety ? tap water ? medicine ? construction ? etc ...
Well, may be its just me, I had goose bumps just to think about it.
-
It is probably a balancing act between reasonable regulation and "getting in the way of progress".
Striking a good balance in anything is always a challenge...
-
But MCAS (the Maneuvering Characteristics Augmentation System) per se is not the problem, the problem is whatever it is that makes it (mal) function not-as-intended, be it the sensors, the circuitry associated with the sensors, or a bug à la toyota in the software.
partially agree..
As a side note: to keep nose within a certain angle tolerance, the system obeys the PID controller rules.
There's a complex issue there, I guess;
-unknown external factor(s) which is just swinging that system based on PID controller rules (here could be many sub-items)
- attack angle sensor is OK, however, in certain conditions its signal cannot be processed properly by system (air flow whirl at place where sensor(s) mounted, micro/macro swinging of fuselage or whatever)
- attack angle sensor is NOK, low reliability
- PID controller is not capable to process exceeding certain limits incoming values, due to wrong coefficient settings or so;
- it is not possible in principle to design an appropriate PID system, due to exceeding all limits external factors (e.g. much unbalanced fuselage)
-missing of elementary redundancy (that not the case, I think, it's aviation);
-influence redundand control channels on each other, somehow (code, conception mistake);
-a lack of option to override that system (code, conception mistake);
-no docs and corresponding training program on that system behaving and misbehaving;
BR
Generally speaking, the PID regulation rules it's foundation of automation based on 'higher mathematics' and constant head ache by students.
From the descriptions given, the MACS system is much simpler than PID, more like a simple on/off if hitting the limit. Per se this may not be a problem - though for me as a non pilot I don't see how this would make the new plane to be more similar to the old one and avoid extra training. To me it makes things worse not better, even if working as intended. The real problem are additional faults - some of them really blatant:
1) not using redundancy, though redundant hardware is there.
There was the optional check program to indicate sensor discrepancy - but this did not work in most cases.
2) not checking for non plausible sensor inputs - especially important when using only 1 of the sensors.
3) not telling and instructing the pilots the system was even there. So to the pilots the system acts like a system male-function. There where even such reports. Telling the pilots would possibly need extra training - kind of negating the very reason the system was there.
4) the extra pilot information issued after the 1st crash was not very clear.
So there are 2 mistakes from the technical side and 2 from the instructions / information.
-
1) not using redundancy, though redundant hardware is there.
There was the optional check program to indicate sensor discrepancy - but this did not work in most cases.
2) not checking for non plausible sensor inputs - especially important when using only 1 of the sensors.
3) not telling and instructing the pilots the system was even there. So to the pilots the system acts like a system male-function. There where even such reports. Telling the pilots would possibly need extra training - kind of negating the very reason the system was there.
4) the extra pilot information issued after the 1st crash was not very clear.
Agree with all that. 1) and 2) are basic design mistakes IMO.
Point 3) is interesting. The system was meant to correct a plane design issue. I suppose that openly talking about it in details would have been problematic for Boeing marketing-wise. I personally think this is their main mistake here, and a very severe one. Not the fact they had to implement it. The fact they almost slid that under the carpet.
And point 4): this is indeed completely mind-boggling there was a second occurence.
-
Boeings killer Planes (2019) Panorama Documentary: https://www.dailymotion.com/video/x7eqscu (https://www.dailymotion.com/video/x7eqscu)
-
Further testing reveal more problems, more delays for Boeing; Cosmic ray "bit-flipping" at high altitudes also considered.
https://www.seattletimes.com/business/boeing-aerospace/newly-stringent-faa-tests-spur-a-fundamental-software-redesign-of-737-max-flight-controls/ (https://www.seattletimes.com/business/boeing-aerospace/newly-stringent-faa-tests-spur-a-fundamental-software-redesign-of-737-max-flight-controls/)
-
The text so says that the override switches in the instrument panel are disabled when mcas is active.
Very interesting..
-
After reading the Seattle Times article I was somewhat surprised to see that single bits are allegedly used to report the in flight status of critical systems. Common sense says that you can't rely on a single bit in a safety crital system. As for cosmic ray bit flipping, unlikely, but it has to be tested, both crashes were at low altitude. A cosmic ray will flip any bit anywhere and anytime, that could apply equally to instructions, status bits, address bits, data bits or any other bit. I think the Seattle Times article is journalism filling in the blanks. Boeing design space hardware so they know about the effect of cosmic rays.
-
Test pilots private conversations on 737 MAX:
https://www.youtube.com/watch?v=btZXVPfh-pE (https://www.youtube.com/watch?v=btZXVPfh-pE)
-
Prediction: The 737 Max will not fly again.
I stand by this prediction.
-
Prediction: The 737 Max will not fly again.
I stand by this prediction.
Too bad this isn't a gambling site. I'd take your money betting that it will fly again.
-
I also think it will fly again, but there is a high risk of delays. A LOT of work and testing will have to be completely squeaky cleanly completed first... by the book, dotting the i's and crossing the t's, by both Boeing and the FAA who are both in the searchlight. A very bright searchlight - almost more like X-rays than light... there just isn't going to be any give and take, perfect is the new official standard.
-
But this will relieve the pain a bit: https://www.ch-aviation.com/portal/news/82115-united-states-imposes-10-tax-on-airbus-aircraft (https://www.ch-aviation.com/portal/news/82115-united-states-imposes-10-tax-on-airbus-aircraft)
-
At this point, we just don't know what Boeing's strategy is going to be, and we don't know whether they can regain trust on this model.
The whole point will be whether it's economically viable for Boeing to do whatever it takes to make the 737 MAX fly again AND regain enough trust. Then again, if they give up on this model, their credibility (which is already damaged) will go down the drain... very challenging times for Boeing. We'll see if Boeing's current management is up to the task... but I have some doubts.
-
At this point, we just don't know what Boeing's strategy is going to be, and we don't know whether they can regain trust on this model.
The whole point will be whether it's economically viable for Boeing to do whatever it takes to make the 737 MAX fly again AND regain enough trust. Then again, if they give up on this model, their credibility (which is already damaged) will go down the drain... very challenging times for Boeing. We'll see if Boeing's current management is up to the task... but I have some doubts.
They may re-buy, upgrade and sell all the planes to military, still making $$.
-
Even if the MAX is abandoned, any new model from Boeing would still be going on a trip through the X-ray machine. Whereas if they fix the MAX and restore credibility all round, they may be able to launch a few more derivatives of that model in future, based on the work being done now - making it an investment for the future as well as recovering from a serious error.
-
I wonder how much it would take to get all of those planes back into the air now. It must be getting on for a year now. There are too many of them for airlines to have stored them in ideal 'laid-up' condition.
Most must have been sat completely unpowered on the tarmac (not to mention Boeing's car park) out in all sorts of weather, getting damp and musty. Taking a car as a trivial example, it's at least a new set of tyres, brake disks and batteries all round, before you even get started on the hydraulic systems and the engines. :-\
-
Imo, up to this stage, the only possible to fly is thru political maneuvers and backup by politicians, of course, compromises included ... nasty. >:D
Unless Boeing turning into non profit organization. :-DD
-
Imo, up to this stage, the only possible to fly is thru political maneuvers and backup by politicians, of course, compromises included ... nasty. >:D
Unless Boeing turning into non profit organization. :-DD
You have to factor in Trump's new tariffs on Airbus too, with it's consequential knock on effect on Scotch Whisky exports (Huh?).
https://www.bbc.co.uk/news/uk-scotland-scotland-business-49915034 (https://www.bbc.co.uk/news/uk-scotland-scotland-business-49915034)
-
Those 3 year old text messages tanked the stock almost 10% and pissed off the FAA.
Boeing's blowing it off as old simulator software. The Board met yesterday, and Muilenburg is in front of Congress in a couple weeks. He's only worried about eluding criminal charges.
They're going to have to halt production, can the CEO and conduct an enema of the corporation.
The fiasco has cost 346 lives and $8B so far.
It's the worst possible scenario- making an existing design safe and wonderful is usually impossible. You can't add in safety if fundamentally the plane's aerodynamics are unstable.
-
You can't add in safety if fundamentally the plane's aerodynamics are unstable.
In that regard all the fighter planes are much much worse, and fly wonderfully. Let's not forget what the problem's been: 50% software bug + 50% incompetence in the cockpit.
-
If the 737 Max doesn't fly, it'll cost Boeing ...
$100 million per aircraft, 387 aircraft = ~$38.7 billion in sales...
...in addition to unrealised support/parts revenue, loss of sales to Airbus and reduced customer confidence, cost of recycling the parts, plus the unrealised assembly & manufacture costs (they suddenly aren't making 5000 aircraft with those tools), and the entire program will be written off.
Could be a $100 billion write down once it is all considered... equal to their yearly revenue.
I don't think it will happen but it could easily sink the company or force a split/merger.
The US would never let Boeing properly fail (with Trump who knows, but in normal times it wouldn't happen) but it sure is going to be painful.
-
You can't add in safety if fundamentally the plane's aerodynamics are unstable.
In that regard all the fighter planes are much much worse, and fly wonderfully. Let's not forget what the problem's been: 50% software bug + 50% incompetence in the cockpit.
Fighter aircraft are deliberately made unstable so that they can maneuver faster, they then have computer control systems to stop them crashing but they still fall out of the sky, it is just that they dont get so fussed about that as it is normally over terrain where there is no one underneath and the pilot can bail out.
Not many passengers would fly again if the plane they were on got junked around the sky in the fashion a fighter plane does.
-
You also need to have some thrust to weight ratio handy with those unstable planes. The fighter jets get the T/W around 1.0, the passengers planes 0.2-0.3..
-
You can't add in safety if fundamentally the plane's aerodynamics are unstable.
And that is exactly the problem. No matter how many software fixes or hardware safety system bodges, the design is fundamentally aerodynamically flawed - the result of corporate greed overshadowing engineering common sense.
If they somehow convince/connive/bribe the FAA/politicians into allowing it to fly again with new and approved bodges, it will be a ticking time bomb.
-
The 737-Max is aerodynamically stable. It does not diverge from controlled flight in pitch on its own.
What it fails to pass is the certification requirement for sufficiently linear stick control forces.
https://www.law.cornell.edu/cfr/text/14/25.175 (https://www.law.cornell.edu/cfr/text/14/25.175)
The requirements have the form of "In configuration <XYZ>, the stick force curve must have a stable slope at all speeds within a range which is the greater of <range definition> above and below the trim speed."
It is this linear stick force curve requirement that was failing that MCAS was implemented to address. The airplane still has positive aerodynamic stability even with MCAS disabled.
-
^That's another way of saying "unstable."
Unstable doesn't necessarily mean the plane can't be flown without electronic aid, requiring 50 corrections per second. Instability can be slow/gradual.
The airplane still has positive aerodynamic stability even with MCAS disabled.
The MAX is unstable at higher AOA. It will fly just fine, as long as the pilot keeps one eye on his pitch/AOA while doing w/e else he has to do. When things go wrong, you don't want to have to juggle so many things, and it's during takeoff and landing that you generally have things going wrong and are flying at a high AOA. It would also come into play in bad weather with shifting up/down drafts.
Test pilots complained for reasons. No matter how you want to word it, the plane doesn't behave as well after the modification. "Requiring more corrective force" sounds benign, but the plane can even run out of elevator range (no matter how hard he presses on the stick? Still not enough!) before the pilot realizes it, which is what MCAS is for. MCAS adjusts the stabilizer to get the elevators back into range for condition, but then the hydraulics can become the weak link. The elevator didn't need to do as much in the original design. It didn't have this additional nose up force that appears and gets even stronger at higher AOA.
Ideally, horizontal stabilizer adjustment would be for convenience. It was never meant to be a main maneuvering surface. Once adjusted, the plane should be able to fly to its limits without having to touch it, again. For the MAX, this is apparently not the case.
-
"Instability" might be the wrong word for it - the nacelle's lift and mounting the engine in front of the wing, ahead of the plane's center of gravity - a positive feedback loop leading to a stall. How bad is it?
Some team at Boeing was in charge of MCAS, identifying the need for it, flew the plane with those settings and changes, and put that behavior into the flight sim, as well as the transgressions.
-
The horizontal stab trim is not a “merely for convenience” flight control in an airliner, but is rather a control surface that is trimmed for each substantial airspeed change. (It’s the “raar-raar-raar” spinning crank sound that you hear periodically on every approach as the aircraft slows. You can also sometimes hear it on takeoff and climb out, but there other noises sometimes dominate.)
-
^That's another way of saying "unstable."
No, it’s not.
Aerodynamic stability has a defined meaning.
At most, it’s insufficiently positive stable, but it still exhibits positive stability (does not go neutral or negatively stable) throughout its flight envelope.
The airplane still has positive aerodynamic stability even with MCAS disabled.
The MAX is unstable at higher AOA.
No, it’s not. https://www.quora.com/Is-the-Boeing-737-MAX-aerodynamically-unstable-I-have-read-that-the-new-heavier-and-higher-mounted-engines-have-changed-its-center-of-gravity/answer/Alan-Dicey (https://www.quora.com/Is-the-Boeing-737-MAX-aerodynamically-unstable-I-have-read-that-the-new-heavier-and-higher-mounted-engines-have-changed-its-center-of-gravity/answer/Alan-Dicey)
-
Apologies for stating opinion like fact. "Lower margin of stability," per the link. But still stable. And with the suggestion that it is perfectly airworthy, EXCEPT that it doesn't meet original cert? Ok, that sounds reasonable.
Per link, the higher the AOA, the more force the pilot has to exert in the original 737 (and is the goal in all planes). But in the MAX the force decreases. According to him, it doesn't increase less. It decreases from the force required at a more moderate AOA.
Unless the pilot has freak proprioception of large muscle groups, he can't tell the exact location of the yoke so much as how much force he is putting on it. In turbulence or extreme corrective maneuvering, it might even be hard to feel if/when the yoke is (net) moving. So while the plane might still be "aerodynamically stable," this is obviously undesirable for any plane, even if it were a new design. IMO.
-
Imo, up to this stage, the only possible to fly is thru political maneuvers and backup by politicians, of course, compromises included ... nasty. >:D
Unless Boeing turning into non profit organization. :-DD
You have to factor in Trump's new tariffs on Airbus too, with it's consequential knock on effect on Scotch Whisky exports (Huh?).
https://www.bbc.co.uk/news/uk-scotland-scotland-business-49915034 (https://www.bbc.co.uk/news/uk-scotland-scotland-business-49915034)
Afraid those are just precursors, more are coming like a carpet bombing the whole Europe.
Not sure bout you Brits though, assuming once you're detached from EU as in Brexit, the bargaining power will not be as strong as EU as the whole, like below "opinionated" column ...
Read thoroughly here -> China tariff deal was easy compared to the EU’s bazooka-proof trade walls (https://www.cnbc.com/2019/10/21/china-tariff-deal-was-easy-compared-to-eus-bazooka-proof-trade-walls.html)
Ok, enough off topics. ::)
-
But this will relieve the pain a bit: https://www.ch-aviation.com/portal/news/82115-united-states-imposes-10-tax-on-airbus-aircraft (https://www.ch-aviation.com/portal/news/82115-united-states-imposes-10-tax-on-airbus-aircraft)
What a coincidence... :palm:
-
I won't discuss the merits of tariffs or lack thereof (another topic entirely), but I just think, given the whole context, that it actually won't help Boeing whatsoever. It just conveys the idea that the only way to save Boeing now is to artificially help it through State meddling. Not something most Americans are fond of, AFAIK.
-
Actually the reason for the Airbus tariffs don't have to do anything with the 737Max, seriously, but with EU subsidies.
I beg to differ. It has everything to do with it IMO, on several levels.
First, it's obvious that it comes from Boeing difficulties, which ARE related (even though not only, I admit) to the 737 MAX debacle.
Second, the whole history of the 737 MAX itself mainly comes from the harsh competition with Airbus. Had Airbus not threatened Boeing as it does, the 737 MAX would never have seen the light.
What Boeing had done to counter Airbus on a significant market, namely the 737 MAX, has become a curse: worse than the previous state of things. So for the time being, and until things get ironed out, they are worse off than they were before.
The subsidies is just a pretext. As you just said, Boeing has been getting subsidies in various forms for decades. The US economic model may be a bit different, but the amounts, I'm not sure. I'd even venture that Boeing may have gotten more public money than Airbus from the start, but this is just a guess (don't have the figures). Just saying - this is all a pretext to try and save Boeing IMO. Sure it also comes from a general "economic war", but with a very concrete basis here.
-
The elephant in the room (re. tariffs) is that the USA has an unsustainable trade deficit - and has only recently woken up to the need for import tariffs to help manage the problem. Now that they have been implemented, we can be pretty confident that they are never going away again...
-
Oh, yeah. But since I don't really buy the "recently woken up", the interesting part is understanding why the trade deficit is suddenly becoming a problem.
-
USA probably hasn't "suddenly woken up" to the trade deficit, it is more likely that (especially in the wake of the financial crisis of '07) the powers that be have given up on the previous model that economic growth would solve this problem, so a change of strategy was called for. That which cannot possibly keep going on, won't... eventually.
Most countries / trading blocs use tariffs to manage financial flows, the USA is a laggard here and is only really beginning to do what everyone else does (probably for pretty much the same reasons).
-
In terms of keeping 737Max in the air, or not...
One significant factor that had not been mentioned is pilot certification. A pilot certified to fly on a certain variant needs to stay certified and to do so the pilot needs fly-time on the plane. Not so long ago, there was a news item titled something like "737 Max flies again, but...". It was an FAA authorized flight for pilot certification or to retain the pilot certification. I don't recall exactly, but there were other special circumstances. (If I recalled correctly) They needed to have at least some pilots capable of moving the grounded MAX around.
With 737-Max grounded for so long, I suspect many more pilots may need to fly a bit again to remain certified. Whether there is an increasing pilot certification flights granted may be the indicator if 737-MAX is staying alive or heading to the grave yard.
I am in the school of thinking 737-MAX will stay alive rather than left dead.
-
Seems like if the plane is stable and perfectly safe (just different) without MCAS, then the worst case would be remove MCAS and recertify as a new airframe?
I think it costs less than 8 billion dollars, but maybe I'm wrong. With all the grounded planes and customer recompensation accumulating, you would think recert would be peanuts. Unless MCAS is necessary to make the plane safe.
-
USA probably hasn't "suddenly woken up" to the trade deficit, it is more likely that (especially in the wake of the financial crisis of '07) the powers that be have given up on the previous model that economic growth would solve this problem, so a change of strategy was called for. That which cannot possibly keep going on, won't... eventually.
Most countries / trading blocs use tariffs to manage financial flows, the USA is a laggard here and is only really beginning to do what everyone else does (probably for pretty much the same reasons).
In my view, "Suddenly woken up" is an appropriate description. Bush II was preoccupied with 9/11 and the military actions after. Obama was preoccupied with "fundamentally changing America". So no one was caring about the trade deficit or the resulting joblessness. Most in the political world or journalism world did not expect a Trump victory. The pressure that was building up was missed by folks. So it appears sudden to many or even most.
Frankly, it is not surprising that those with a job would not see the trade deficit and the resulting joblessness being an issue. They go on with their lives thinking all is well, and I am sure it was for them. The ones in affected occupations would be largely invisible to the job-holders. Exception is the mail-delivery guys. About mid-way into Obama's second term, I was friendly with my former mail-delivery guy who is also former US Marine. He told me one in four households (on his route) were receiving unemployment benefit checks.
-
Seems like if the plane is stable and perfectly safe (just different) without MCAS, then the worst case would be remove MCAS and recertify as a new airframe?
I think it costs less than 8 billion dollars, but maybe I'm wrong. With all the grounded planes and customer recompensation accumulating, you would think recert would be peanuts. Unless MCAS is necessary to make the plane safe.
MCAS is necessary to meet the certification requirements under Part 25. I provided the link to the specific law above.
I don't think it's "perfectly safe" without MCAS; I do think that MCAS is an appropriate fix to ensure compliance with Part 25 rules.
-
USA probably hasn't "suddenly woken up" to the trade deficit, it is more likely that (especially in the wake of the financial crisis of '07) the powers that be have given up on the previous model that economic growth would solve this problem, so a change of strategy was called for. That which cannot possibly keep going on, won't... eventually.
Most countries / trading blocs use tariffs to manage financial flows, the USA is a laggard here and is only really beginning to do what everyone else does (probably for pretty much the same reasons).
In my view, "Suddenly woken up" is an appropriate description. Bush II was preoccupied with 9/11 and the military actions after. Obama was preoccupied with "fundamentally changing America". So no one was caring about the trade deficit or the resulting joblessness. Most in the political world or journalism world did not expect a Trump victory. The pressure that was building up was missed by folks. So it appears sudden to many or even most.
Frankly, it is not surprising that those with a job would not see the trade deficit and the resulting joblessness being an issue. They go on with their lives thinking all is well, and I am sure it was for them. The ones in affected occupations would be largely invisible to the job-holders. Exception is the mail-delivery guys. About mid-way into Obama's second term, I was friendly with my former mail-delivery guy who is also former US Marine. He told me one in four households (on his route) were receiving unemployment benefit checks.
Before the 2007 financial crisis, the growth model in the USA (and to a significant extent, also the UK) was based on selling houses to each other at ever increasing prices, while taking out loans based on property valuations to spend on consumption / import. That whole house of cards collapsed, as we know, and there is much less money to go round today as a result. This gave us Trump in the USA, and Brexit in the UK.
Getting Boeing "fixed" is a part of the cure, in my view. Getting back to a strong focus on "making real things" and "making them good" is a time honoured principle that beats financial voodoo in the long run. (See Japan/Germany today, and US/UK in the past)
-
Sokoloff:
So the Boeing is aerodynamically stable, but it does not demonstrate longitudinal stability?
And it is allowed to be fixed through electronic chicanery? Maybe if they put some rubber bands on the stick in just the right spots, it would also pass? :)
14 CFR § 25.175 - Demonstration of static longitudinal stability.
CFR
Everything I had read, prior, suggested that the Beoing needed MCAS ONLY so it would be "grandfathered in" under the original 737 cert. This sounds like it might be way more serious (which is what I suspect?).
-
:palm: It is aerodynamically stable (which, when unqualified, typically means "longitudinally stable", being one of three axes of stability and roll and yaw stability are rarely the concern), in the sense that it exhibits positive stability (as contrasted with the alternative adjectives: neutral or negative).
It does not demonstrate longitudinal stability consistent with that required by that certification part, which requires specific performance in order to demonstrate safe, predictable control forces. The fix is electronic control of a (slow-moving) mechanical control surface to meet certification requirements.
I'm not sure what's confusing. The airplane is stable. It's not stable "enough" for certification. Properly implemented MCAS is a perfectly good fix.
-
The identically designed Max would have required MCAS (or another fix) to meet certification requirements.
MCAS may have been designed the precise way that it was in order to qualify on the existing A16WE type certificate, but some fix (almost surely an aerodynamic one, whether MCAS or other) would be required to be certified under part 25 in any event.
-
^Thanks, really. Your post is covering concepts that are hard to convey in the readers digest or popular news.
So the MAX, even if it were certified as a new plane not connected to the 737-100, would not pass (without MCAS).
So as long as a plane is slightly positively stable, the airframe is ok? We can then use electronics to make it feel/behave MORE stable, longitudinally or otherwise, to the pilot, in order to meet the more stringent stability requirements. But we can't (with passenger planes) cross into neutral or negative aerodynamic stability and go fixing that with computers?
BTW, I edited my previous post while you were posting yours. I'll go back and put it back to how it was. Just added a few words.
-
Seems like if the plane is stable and perfectly safe (just different) without MCAS, then the worst case would be remove MCAS and recertify as a new airframe?
I think it costs less than 8 billion dollars, but maybe I'm wrong. With all the grounded planes and customer recompensation accumulating, you would think recert would be peanuts. Unless MCAS is necessary to make the plane safe.
Besides the MCAS problem, they found other problems with the control software. So they will have to do a fix if the system anyway. Fixing MCAS may very well be the easier part. Getting a complete new certification would need it to meat newer standards and also a lot of time. It is the delays that make the process expensive. Not the maybe 10 man-years for the specialists to rewrite the code - that is peanuts.
The usual planes are stable only for a limited AOA range. The changes to the airframe reduced the stable range - not sure if too much, but at least too much to get the same flight certificate.
If turning off MCAS would be the remedy to handle a single faulty sensor - the plane should be safe without and the pilots must be able to fly it without MCAS. So I can't follow the argument that an unreliable MCAS could bring the plane to the same type class. It is more like making the system more complicated needing extra training.
-
^Thanks, really. Your post is covering concepts that are hard to convey in the readers digest or popular news.
Thanks; that line means a lot. I have to admit I was getting a little frustrated at times during our exchange, but I tried to keep it civil and factual, because there's an awful lot of misinformation out there and decoding aviation speak isn't always easy (especially if the goal of many journalists is fomenting outrages and harvesting clicks). Boeing's not blameless here for sure, but neither do I think they acted like total idiots.
So the MAX, even if it were certified as a new plane not connected to the 737-100, would not pass (without MCAS).
100% right if they are constrained to keep the landing gear and wing of the 737.
But, if you look at it differently, if they were willing to go for a from-scratch certification, they would likely have created taller landing gear, providing for more underwing space to hang the larger engines farther back, moving the center of thrust rearward and center of pressure slightly rearward. It's possible that they might have managed to get the pilot type rating to crossover even without the airplane being built on the same type certificate. (The 757 and 767 are built on A2NM and A1NM TCDS, respectively, but share a common type rating: "B-757, B-767".)
All of that is fairly academic though as the 757 and 767 are the only airplanes to share a common type rating, it's not very likely that Southwest and the like would buy a 737-Max class airplane that wasn't on the A16WE TCDS, and such a 737 would probably look an awful lot like the 757, which Boeing already has...
So as long as a plane is slightly positively stable, the airframe is ok? We can then use electronics to make it feel/behave MORE stable, longitudinally or otherwise, to the pilot, in order to meet the more stringent stability requirements. But we can't (with passenger planes) cross into neutral or negative aerodynamic stability and go fixing that with computers?
I don't think there's anything to directly prevent the certification of an inherently unstable airplane with sufficient fly-by-wire mods to make it behave stably. Such fly-by-wire mods (and the associated power sources) would then become subject to mitigation against Catastrophic event severity, meaning you'd have to reduce the projected frequency of occurrence of such a failure to lower than 1 in 109 (1 [US] billion) flight hours. In practice, because there's no great advantage to making a passenger airliner unstable, airliners are stable inherently and have minor mods here and there to tweak performance and handling. Military aircraft which are inherently unstable rely on electronic controls and ejection seats as the ultimate backstop. They're also accepting of some amount of fatalities if that prevents greater fatalities in usage.
The airplane is certified as a system. That system must pass all certification requirements while everything is working as designed.
It must also have analysis done to consider the effects of degraded operation as various systems are inoperative. The effect of an MCAS system failure was judged (IMO reasonably) to be "hazardous", one level lower than catastrophic. This requires failure modes to exhibit themselves fewer than 1 in 10,000,000 flight hours (1 in 107 hours). Hazardous is characterized by a "Large reduction in safety margin or functional capability."
Boeing is going to wear a lot of this. It turns out that their analysis of frequency of failure was very likely wrong. It turns out that crews didn't react quickly and appropriately to the presentation of the MCAS fault. (NB: the guidance document provides a reminder: "Crew physical distress/excessive workload such that operators cannot be relied upon to perform required tasks accurately or completely") It turns out that the system was delivered with a higher control authority than originally contemplated (however that would still likely only result in a "hazardous" categorization). It turns out that crews could trigger multiple cyclic activations of MCAS, further increasing the authority of the stabilizer.
I have a certain amount of sympathy for Boeing engineers here. They screwed up, but I'm not nearly as convinced it was part of a diabolical scheme to separate airlines from their money and ship an unsafe product, but rather a drive to push a longer-range, more economical aircraft into a crowded market.
Ref - https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/risk_management/ss_handbook/media/chap3_1200.pdf (https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/risk_management/ss_handbook/media/chap3_1200.pdf)
-
[the Max fail was the result of...] a drive to push a longer-range, more economical aircraft into a crowded market.
It seems plausible that this is the reason, when all is said and done. But it is not a good reason... are there ever any commercial projects that are not under time pressure?
-
They're under economic pressure to compete. It's not like stretching type certificates for derivative models is a novel thing or Boeing-specific.
The 737-900 is leagues different from the 737-100.
The Airbus A318, A319, A320, and A321 are all built on a common type certificate (EASA.A.064) and I count 47 individual models/variants of airplanes built on that type certificate.
-
Ref - https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/risk_management/ss_handbook/media/chap3_1200.pdf (https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/risk_management/ss_handbook/media/chap3_1200.pdf)
Everything related to FAA is pointless, as its now considered no better than those easy to lobby, getting cozy ... to be bribed government regulatory/safety related institutions like in those piss poor developing countries.
Even Boeing managed to survive this event, the cost of selling any US made airplanes, not only from Boeing, will be sky high as now every developed countries need to re-certify it, as FAA's certification considered a junk now.
A bold move from gov. or politicians are desperately needed now than ever, especially for international markets.
-
They're under economic pressure to compete. It's not like stretching type certificates for derivative models is a novel thing or Boeing-specific.
The 737-900 is leagues different from the 737-100.
The Airbus A318, A319, A320, and A321 are all built on a common type certificate (EASA.A.064) and I count 47 individual models/variants of airplanes built on that type certificate.
Absolutely - and if the job had been done properly, nobody would have had a problem with it.
When all is said and done, Boeing and the FAA released a product that was - overall - flawed enough to be a real problem. They somehow failed to strike the right balance between financial interests and engineering realities. This can only be fixed by raising the level of play substantially to regain trust.
-
A BBC news report - it looks as if heads have started rolling at Boeing, prior to their Q3 results publication later today...
https://www.bbc.co.uk/news/business-50151573 (https://www.bbc.co.uk/news/business-50151573)
The Indonesian investigators final report on the Lion Air crash is expected to be published on Friday.
EDIT: The story and content have since been updated from the previous title and is now saying that Boeing expect the 737MAX to be flying again by the end of the year.
-
The FAA is going to say they need more taxpayers $ to do their job right... That's how the public sector works!
-
EDIT: The story and content have since been updated from the previous title and is now saying that Boeing expect the 737MAX to be flying again by the end of the year.
It's the only practical way to get them there. https://www.airplaneboneyards.com (https://www.airplaneboneyards.com)
-
Boeing is flying 737-Max under ferry permits or experimental flight test protocols now and has been for a while. They’re still building them and relocating them to other fields.
When the financial news media says “will be flying”, they mean in revenue service not merely leaving the ground.
-
They're under economic pressure to compete. It's not like stretching type certificates for derivative models is a novel thing or Boeing-specific.
The 737-900 is leagues different from the 737-100.
The Airbus A318, A319, A320, and A321 are all built on a common type certificate (EASA.A.064) and I count 47 individual models/variants of airplanes built on that type certificate.
Oh of course, this is common practice, and there's nothing fundamentally wrong with it.
I (along with many others) just think Boeing has gone a step too far with the 737MAX.
There's something to also consider here. Yes the 737 essentially competes with the A320 family. But the 737 was released in 1968. The A320 (first of the family AFAIK) in 1988, 20 years later. Sure both lines have evolved significantly, but still.
Impressive longevity, but I guess at some point it becomes unreasonable to keep milking the cow.
-
Boing flies into darker weather!
Spirit Florida orders 100 planes from AirBus
https://www.zerohedge.com/markets/boeing-backlash-begins-spirt-airlines-orders-100-new-airbus-planes (https://www.zerohedge.com/markets/boeing-backlash-begins-spirt-airlines-orders-100-new-airbus-planes)
India orders 300 planes from Airbus!
https://www.zerohedge.com/markets/boeing-backlash-indias-indigo-order-300-jets-airbus (https://www.zerohedge.com/markets/boeing-backlash-indias-indigo-order-300-jets-airbus)
Blancoliro says it 737Max will be certified and out fly soon, Senate hearing.
https://www.youtube.com/watch?v=QZO7sIbWrX8 (https://www.youtube.com/watch?v=QZO7sIbWrX8)
-
http://knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf (http://knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf)
The final report is out. It makes for a sobering read.
-
Indeed. Crew fights with electric trim from 23:25:27 through 23:31:46 activating nose up manual trim 32 times for 143 seconds (of the 379 elapsed seconds, or 38% of the time).
That's absolutely abnormal and yet the crew never recalls the runaway stabilizer trim memory items nor calls for the runaway stabilizer checklist.
They were dealt a confusing situation with the IAS DISAGREE and angle of attack difference. That may have contributed to their failure to identify the appropriate response.
-
That may have contributed to their failure to identify the appropriate response.
At least the captain (somehow, inadvertently) sensed that trim was being a problem, because he kept correcting it good enough, obeying the #1 rule fly the plane, but the FO...
At 23:30:48 UTC, the Captain asked the FO to take over control of the aircraft
...failed big time to fly the plane!
I too wonder why the captain didn't flip the stab trim cutout switch after all that fighting against auto trim, or put the flaps back to pos 1. He should have known to do that. I wouldn't expect the FO to grasp or infer any of that, much less in a sec, because there's a reason why they're still FOs and not captains: lack of experience.
-
This part says a lot though:
In the event of multiple MCAS activations with repeated electric trim inputs
by flight crew without sufficient response to return the aircraft to a trimmed
state, the control column force to maintain level flight could eventually
increase to a level where control forces alone may not be adequate to control
the aircraft. The cumulative mis-trim could not be countered by using
elevator alone which is contrary to the Boeing assumption during FHA.
-
That's absolutely abnormal and yet the crew never recalls the runaway stabilizer trim memory items nor calls for the runaway stabilizer checklist.
Warning! I’m not involved in aviation in any way. My posts may be mistaken.
My impression is that retrimming the plane is like breathing for a pilot. You climb, descend or turn and you retrim. A few minutes pass while on autopilot and you retrim. You scratch your belly and you retrim.
If you’re always adjusting the trim on instinct, what threshold do you need to notice that you are trimming more than normal?
A pilot’s insight would be enlightening. How often is normal for manual trimming? Also, how often does MCAS and the previous Speed Trim System normally activate?
My impression is that MCAS and STS would make detecting runaway stabilizer very difficult. You’re manually flying along and the trim motor activates briefly. Without hard guidelines of what’s normal, how would would you know if it’s too much?
-
It is close to breathing in terms of how much concentration it requires to activate, but it’s also quite normal that trimming occurs primarily around speed or configuration changes. Raise the flaps? Might need to trim. Accelerate to second stage climb, might need to trim. It’s not the case that you’d be trimming over and over, only to have the airplane trim against you (with associated audible and visual indications) right afterward.
With that amount of trim activity required without any associated configuration or speed change, it would be flagged as abnormal to most pilots.
For context only, I have about 1300 flight hours in several different high performance single and twin piston airplanes but only have somewhere around 20 jet hours, including around 5 in a level D full motion 737 sim.
-
Wow!
Thank you for your direct insight and knowledge.
The report suggested that the stab trim motor may have gone unheard due to the noise from the continuous stick shaker activation. I found that very alarming. Wouldn’t incorrect activation of the stick shaker be serious enough to declare MAYDAY right away?
The crew of the previous flight who successfully recovered the same faulty aircraft decided to fly the whole flight with the sticker shaker activated! That seems crazy to me.
-
To bring this report on topic on ”The biggest T&M forum on the net”, the incorrect use of an angle measuring instrument led to the faulty repair of the AoA sensor.
The approved instrument was substituted with one that had an extra switch labeled REL/ABS. If the instrument was switched out of absolute mode into relative mode by mistake, it would lead to an AoA sensor carefully aligned to a completely random incorrect angle.
-
The repaired AoA sensor left it with a 21 degree offset, which was not noticed by Lion Air's maintenance team.
Xtra Aerospace was not qualified to do the repair of the AoA sensor in the first place, now the FAA revoked their repair certification license.
https://www.aviationtoday.com/2019/10/28/lion-air-737-max-final-accident-report-cites-aoa-sensor-mcas-as-contributing-factors (https://www.aviationtoday.com/2019/10/28/lion-air-737-max-final-accident-report-cites-aoa-sensor-mcas-as-contributing-factors)
-
Xtra Aerospace was not qualified to do the repair of the AoA sensor in the first place, now the FAA revoked their repair certification license.
In fact their web site no longer appears to exist and their parent company, Wencor Group, has no mention of them on their website. Not surprising if you get your certification pulled I suppose.
-
Wouldn’t incorrect activation of the stick shaker be serious enough to declare MAYDAY right away?
Probably not Mayday, perhaps Pan-pan, or maybe a routine return to the departure airport. Particularly when combined with inappropriate trim activation with an unknown (at the time) cause, it's a matter of serious concern.
The crew of the previous flight who successfully recovered the same faulty aircraft decided to fly the whole flight with the sticker shaker activated! That seems crazy to me.
Yes, you aren't the only one who sees it that way.
-
The priorities, in order, are aviate, navigate, communicate.
Aviate: don’t crash the airplane
Navigate: take it where you want to go
Communicate: let ATC know what’s going on
In this case, saying or not saying Mayday has no practical effect. They were already getting everything they needed from ATC (nothing more would help). I doubt either pilot of either crew had any doubt that they were facing a serious emergency.
-
The report addressed this topic. Yes, the pilots should have ignored ATC and kept all their attention on handling the aircraft. Instead, the pilots responded to the eight heading instructions given by ATC.
Declaring PAN PAN or MAYDAY would have kept ATC quiet, reducing their workload. ATC would have gave them priority, keeping other aircraft out of their way.
-
Xtra Aerospace was not qualified to do the repair of the AoA sensor in the first place, now the FAA revoked their repair certification license.
This is aftermath, but the events leading up to the mistake are more subtle and insidious.
Xtra had to justify the substitution of the angle measuring equipment with documentation. The people who wrote the test equipment equivalency report were either incompetent or unqualified as they missed the extra mode switch and lower accuracy of the substitute equipment.
The report was accepted by the local FAA Flight Standards District Office, who also missed the problems.
-
Something to remember is that, in previous generations of the 737, a faulty AoA sensor could not cause the plane to crash. It would cause one AoA display to be wrong, and perhaps activate one stick shaker. That's not critical.
Only when MCAS was introduced did Boeing give a faulty AoA sensor the power to cause trim changes. And they didn't tell anyone about it, at least not pilots or operators.
So it's understandable that people who didn't know about MCAS would be a bit unconcerned about an AoA sensor.
-
and perhaps activate one stick shaker.
Reading these kinds of reports has made me appreciate the finer details. Yes, this kind of faulty sensor will signal a single computer out of two and activate a single stick shaker out of two. But, as mentioned in the report, both control wheels are physically linked. A single stick shaker will be felt on both wheels. It may not be possible to distinguish a single shaker versus a double shaker activation.
Only when MCAS was introduced did Boeing give a faulty AoA sensor the power to cause trim changes. And they didn't tell anyone about it, at least not pilots or operators.
So it's understandable that people who didn't know about MCAS would be a bit unconcerned about an AoA sensor.
The previous STS uses the same methodology as MCAS. Computer controlled trim is used to enhance control feel during manual flying. It does not use the AoA sensor as an input.
As fly-by-wire is becoming the norm, perhaps more work is needed to improve AoA sensors and fault detection. Airbus had a few upsets and one crash where two stuck AoA sensors caused the rejection of the third.
https://www.flightglobal.com/news/articles/analysis-how-airbus-fought-its-own-pitch-battle-457574/ (https://www.flightglobal.com/news/articles/analysis-how-airbus-fought-its-own-pitch-battle-457574/)
-
This isn't failed engineering, needing improving sensors and fault detection.
It's unbridled corporate greed and corruption, at the executive level.
MCAS had already been properly engineered. From Muilenburg's testimony before Congress this week:
"Michigan Republican Representative Paul Mitchell asked why the 737 Max’s version of MCAS had key differences from a midair refueling tanker Boeing supplies to the U.S. Air Force. He pointed out that the Pentagon required that the KC-46 tanker’s MCAS system activate only once, when the civilian application could -- and did -- fire repeatedly, he said.
“Why the difference? What motivated that?” the lawmaker said.
John Hamilton, chief engineer of Boeing Commercial Airplane division, cited specifications set by the Air Force. Muilenburg said the tanker’s MCAS system was designed for different flight scenarios than the 737 Max’s version. The Air Force has said the KC-46’s MCAS systems incorporated data from two angle-of-attack sensors, rather than one sensor as originally designed on the 737 Max."
When your customer tells you how to do airplane engineering safety |O
He's still among the highest paid CEO's at $23.4M, including a $13.1M bonus, 27% increase from the previous year.
Imagine getting paid that much despite killing 346 people and $9B in losses.
-
This isn't failed engineering, needing improving sensors and fault detection.
It's unbridled corporate greed and corruption, at the executive level.
MCAS had already been properly engineered. From Muilenburg's testimony before Congress this week:
"Michigan Republican Representative Paul Mitchell asked why the 737 Max’s version of MCAS had key differences from a midair refueling tanker Boeing supplies to the U.S. Air Force. He pointed out that the Pentagon required that the KC-46 tanker’s MCAS system activate only once, when the civilian application could -- and did -- fire repeatedly, he said.
“Why the difference? What motivated that?” the lawmaker said.
John Hamilton, chief engineer of Boeing Commercial Airplane division, cited specifications set by the Air Force. Muilenburg said the tanker’s MCAS system was designed for different flight scenarios than the 737 Max’s version. The Air Force has said the KC-46’s MCAS systems incorporated data from two angle-of-attack sensors, rather than one sensor as originally designed on the 737 Max."
--snip--
KC-46 pegasus is derived from a B767 and may have other significant mcas and pitch /trim response differences,
P-8 Poseidon is a more recent issue naval patrol, anti-sub aircraft derived from B737-800ERX, this would be a better comparable but I don't know if it has a modified MCAS.
-
After this saga, all fall back to a very simple fundamental question, how is Boeing better than -> Comac (https://en.wikipedia.org/wiki/Comac) ? :-DD
Example Comac C919, its intended to compete primarily with the Boeing 737 MAX, pretty confident its darn cheap compared to 737 MAX.
Quote : "In 2012 the C919 order book stood at 380 units worth US$26 billion, and averaging $68.4 million. FlightGlobal's Ascend market values in 2013 were $49.2 million for the Airbus A320neo, 51% less than its $100.2 million list price and $51.4 million for the Boeing 737 MAX-8, 49% less than its $100.5 million list price. In June 2015, the China National Radio predicted a $50 million price, cheaper than the B737 or A320 list prices."
(https://upload.wikimedia.org/wikipedia/commons/8/8b/COMAC_B-001A_May_2017.jpg)
Also if the China's FAA equivalent body is proven to accept bribe or made such mistakes, guilty parties for sure will be executed with death penalty, at least this bring more confident isn't it ? >:D
-
After this saga, all fall back to a very simple fundamental question, how is Boeing better than -> Comac (https://en.wikipedia.org/wiki/Comac) ? :-DD
Example Comac C919, its intended to compete primarily with the Boeing 737 MAX, pretty confident its darn cheap compared to 737 MAX.
Quote : "In 2012 the C919 order book stood at 380 units worth US$26 billion, and averaging $68.4 million. FlightGlobal's Ascend market values in 2013 were $49.2 million for the Airbus A320neo, 51% less than its $100.2 million list price and $51.4 million for the Boeing 737 MAX-8, 49% less than its $100.5 million list price. In June 2015, the China National Radio predicted a $50 million price, cheaper than the B737 or A320 list prices."
(https://upload.wikimedia.org/wikipedia/commons/8/8b/COMAC_B-001A_May_2017.jpg)
Also if the China's FAA equivalent body is proven to accept bribe or made such mistakes, guilty parties for sure will be executed with death penalty, at least this bring more confident isn't it ? >:D
That's easy. The 737 exists. The C919 doesn't, except for a few prototypes being used for testing. FIRST delivery isn't planned until 2021, and it'll take time to ramp up production. China internal customers will dominate the output for the next decade or more, assuming no serious flaws show up in service. Some of that market is built-in, since that's an obvious result of having a state-owned aircraft manufacturer and state-owned airlines. As for mistakes, are you sure we'd ever hear about most of them? Most of the media is state-owned as well.
Also, you stopped copying wiki text too soon. Allow me to continue, directly after what you quoted:
The Chinese airlines that have placed orders for the C919 already have either the Boeing 737 or Airbus A320 in their fleets.[66] In 2013, Chinese state-owned newspaper Global Times complained that an Aviation Week editorial about the bleak prospects for the aircraft "maliciously disparaged the future outlook for the C919".[67]
COMAC aims to take a fifth of the global narrowbody market and a third of the Chinese market by 2035.[8] It expects 2,000 sales in the next 20 years.[68] China considers it as a source of national pride.[69] The Financial Times states the C919 is outdated by 10–15 years compared to the latest versions of the A320 and Boeing 737, and will probably cost more to operate.[70] Its range of 2,200–3,000 nmi (4,100–5,600 km) falls short of the 3,400 and 3,550 nmi (6,300 and 6,570 km) of the A320neo and 737 Max 8, the C919 payload-range and economics are similar to the current single-aisles, but it will compete with the Neo and Max. FlightGlobal forecasts 1,209 deliveries: 687 standard and 522 stretched variants, for 85% in China.[31]
-
This 737Max saga cannot get any more sad, even if it is allowed to flight it really doesn't comply FAA rules fully, like clearance between control cables,
One issue is how FAA managers agreed during certification of the 737 MAX to give Boeing a pass on complying with a safety rule that requires more separation between duplicate sets of cables that control the jet’s rudder.
This is to avoid the possibility that shrapnel from an uncontained engine blowout could sever all the cables and render the plane uncontrollable.
The requirement was introduced when such a blowout caused the deadly 1989 crash of a United Airlines DC-10 in Sioux City, Iowa. The 737 has never been brought into line with the requirement
.....The story listed a series of legacy design details that have been repeatedly grandfathered into the latest model each time Boeing has updated the 737, which was originally certified more than 50 years ago.
All the issues in the list were flagged by FAA safety engineers as requiring fixes before the MAX could be certified. But each was waved through after managers on the Boeing side of certification insisted that these were non-issues and managers on the FAA side agreed to let it move ahead with the requirement unaddressed.
So basically Boeing is designing non-compliant and unsafe airplanes like nothing but since it is already designed how the hell is it not going to get certified, the costs would be tremendous!!!
https://www.seattletimes.com/business/boeing-aerospace/new-questions-raised-on-safety-of-both-737-max-and-787-dreamliner/ (https://www.seattletimes.com/business/boeing-aerospace/new-questions-raised-on-safety-of-both-737-max-and-787-dreamliner/)
I'd think a big part of this is just pointing fingers by FAA, as they want to appear to be the "good guys" now. The 737 family has an excellent track record in safety, in general.
Now they claim that the 737 does not comply a 30 year old rule, while obviously no accident was contributed to that non-compliance in that 30 years, come on!
-
[...] they claim that the 737 does not comply a 30 year old rule, while obviously no accident was contributed to that non-compliance in that 30 years [...]
If the rule is incorrect, it should be removed. Otherwise it should be adhered to.
There should be no rules that are arbitrarily ignored just because someone thinks not enough accidents are happening!
-
The problem now is not Boeing, forget any technicality talks, as its pointless.
Its just natural as they're just maximizing the profit, while the safety part is ignored heavily with the great aid and help by FAA.
For so many decades, can you imagine the bribe that FAA officials took ? And maybe politicians too for being quite all this time ?
And please don't be naive, that FAA didn't get or want any catch all by "surrendering" the certification to the Boeing to be "self-certifying" company. >:D
Even its pronounced & written as "Boeing" , still it has the meaning of "One Hung Low" brand inside.
-
[...] they claim that the 737 does not comply a 30 year old rule, while obviously no accident was contributed to that non-compliance in that 30 years [...]
If the rule is incorrect, it should be removed. Otherwise it should be adhered to.
There should be no rules that are arbitrarily ignored just because someone thinks not enough accidents are happening!
My 1965 Mustang doesn’t meet many current federal safety standards. Nevertheless, I can still drive it on the road. I’ve chosen to make a few upgrades (adding dual circuit brakes, not originally equipped, and will likely add three point belts [lap belts originally an option, shoulder belts not offered]), but didn’t have to.
That does not mean I think the shoulder belt or dual circuit braking or reverse lights requirements are bad laws, just that they don’t apply retroactively to machines certified or built before they were introduced.
-
My 1965 Mustang doesn’t meet many current federal safety standards. Nevertheless, I can still drive it on the road.
Lucky you. The bureaucrats in Brussels want to end with that in Europe.
-
Lucky you. The bureaucrats in Brussels want to end with that in Europe.
Rightly so. Why should the community bear the healthcare bills of individuals recklessly injuring themselves and others with unsafe cars?
That does not mean I think the shoulder belt or dual circuit braking or reverse lights requirements are bad laws, just that they don’t apply retroactively to machines certified or built before they were introduced.
This doesn't, shouldn't and has never applied to the aviation industry. As soon as anything is deemed unsafe or outdated, it needs to be changed. Would you let yourself or your loved ones fly on a "no worries mate, she'll be right"-airline?
-
Lucky you. The bureaucrats in Brussels want to end with that in Europe.
Rightly so. Why should the community bear the healthcare bills of individuals recklessly injuring themselves and others with unsafe cars?
Since when does "the community" pay our cars' insurance bills?
-
Since when does "the community" pay the insurance bills?
Most Europeans pay taxes that pay for healthcare, a greater number of car accidents mean more hospital visits and greater costs.
Air pollution & climate change also effect everyone.
-
Surely the point here is not that when the car or plane was first manufactured it complied with the relevant regulations then but that when subsequent models are made they comply with the regulations now pertaining, if you go with what Boing have apparently been doing Ford could lable all their cars Model T and forget about all modern regulations.
-
Since when does "the community" pay the insurance bills?
Most Europeans pay taxes that pay for healthcare, a greater number of car accidents mean more hospital visits and greater costs.
Bollocks. If you have an accident in your "Model T", it's your insurance company that pays the ambulance/hospital/medical care bills, not the NHS.
Air pollution & climate change also effect everyone.
And the polar bears.
-
I'm not a pilot and have only rudimentary knowledge about this. Hopefully not too much of a noob question.... but if a Pitot tube or aircraft speed sensor was blocked or malfunctioning, it would tell the pilot the aircraft is going too slow? So wouldn't they speed up the airplane? Wouldn't speeding up help keep it flying in the air? I would imagine the reverse would be worse, where the sensor is telling you that you are going fast and you slow down and stall.
It's a bit more complicated than that. There is a static port and a pitot port. Speed is reported based on the pressure differential between the two.
If the pitot tube is blocked, it will just report the speed it was reporting at the time it became blocked. Unless you descend, in which case it will start to show lower airspeeds, or if you ascend, in which case it will show higher airspeeds -- none of this having anything to do with your actual airspeed.
If the static port is blocked, but the pitot tube is clear, then you will get a indication of air speed, but as you ascend the speed indicated will be lower than your actual airspeed, etc.
It's a lot of "fun" to reason through when you are literally concerned that your pitot system is malfunctioning.
https://en.wikipedia.org/wiki/Pitot-static_system#Blocked_static_port
-
That does not mean I think the shoulder belt or dual circuit braking or reverse lights requirements are bad laws, just that they don’t apply retroactively to machines certified or built before they were introduced.
This doesn't, shouldn't and has never applied to the aviation industry. As soon as anything is deemed unsafe or outdated, it needs to be changed.
"Has never applied"? This absolutely does apply to the aviation industry. Today.
The airplane I fly was certificated under CAR-3, which was updated to Part 23 in 1965. My airplane was built in 1997 under a CAR-3 type certificate and the design did not need to be updated to any Part 23 rule changes. On transport jets, the same principle applies. 707s still flying need to meet the 707 type certificate, not any subsequent changes to certification (unless those are made mandatory by special FAR or airworthiness directive.) New 707s could still be built if there was economic demand for them.
Would you let yourself or your loved ones fly on a "no worries mate, she'll be right"-airline?
I don't let us fly on certain foreign carriers with a poor training record. I don't have any issue with any EU flag, Swiss, or CA/US/MX flag carrier and would readily let my family fly on any of those. I made an exception once on vacation for a day VMC flight on a carrier that I would not have been willing to use for a night or IMC flight.
Airline travel is almost incomprehensibly safe, even with the fact that airliners are not required to be continually changed and updated as certification rules evolve.
If they were made to be so, there would be pressure to not make incremental improvements to the certification rules (owing to the economic impact on airlines). It's not particularly different from evolving building codes or vehicle codes. We don't seize or make economically unviable people's old buildings or cars; we also don't do the same to airplanes.
-
We don't seize or make economically unviable people's old buildings or cars; we also don't do the same to airplanes.
Hear, hear !!
-
[...] My 1965 Mustang doesn’t meet many current federal safety standards. Nevertheless, I can still drive it on the road.[...]
Awesome car!
...The 2020 Mustang does obey 2020 regulations, though, and Ford does not pass it off as an extended 1965 model...
Is it not true that planes do get updated from time to time, if there are significant improvements that can be retrofitted? I seem to recall winglets being added to older planes at some point, for example.
It is pretty rare that cars get updated for current regulations (but it can happen - e.g. lead free gas required updating the older cars in some cases).
-
Bollocks. If you have an accident in your "Model T", it's your insurance company that pays the ambulance/hospital/medical care bills, not the NHS.
Up to a point in the UK, but only about £300 for emergency treatment and £400 per day in hospital up to £10k maximum. Source: Road Traffic (NHS Charges) Act.
That certainly doesn't even begin to cover the cost of specialist emergency care, prosthetics, dental rework, corrective plastic surgery etc.
-
Is it not true that planes do get updated from time to time, if there are significant improvements that can be retrofitted? I seem to recall winglets being added to older planes at some point, for example.
Yes. There is a generally optional process to modify airplanes such that they differ from their original type certificate. These are “Supplemental Type Certificates” (STCs) and can range from wing mods, avionics, lighting packages, engine modifications or replacements, gross weight increases, or basically anything.
My A36 has several: added turbo, increased gross weight, glass panel PFD/MFD, touch screen WAAS navigators, built-in O2, and probably a few others that I’m forgetting. (Edit to add: tip tanks for 40 gals more fuel and TKS [glycol] anti-ice system)
-
UK Channel 4 9pm tonight.
Boeing's Killer Plane: What Went Wrong?
This documentary unravels the events that led to two modern passenger jets falling out of the sky, and investigates how the fastest-selling aircraft in Boeing's history ended in tragedy
https://www.channel4.com/programmes/boeings-killer-plane-what-went-wrong (https://www.channel4.com/programmes/boeings-killer-plane-what-went-wrong)
-
UK Channel 4 9pm tonight.
Boeing's Killer Plane: What Went Wrong?
This documentary unravels the events that led to two modern passenger jets falling out of the sky, and investigates how the fastest-selling aircraft in Boeing's history ended in tragedy
https://www.channel4.com/programmes/boeings-killer-plane-what-went-wrong (https://www.channel4.com/programmes/boeings-killer-plane-what-went-wrong)
Interesting - although of course limited in what it could cover accessibly from a cold start in an hour.
A couple of takeaways that I hadn't heard...
- The AOA sensor vane was apparently taken off by a suspected bird strike before the second crash (not heard that one before!)
- Boeing engineers anticipated that Pilots would recognise an MCAS (trim?) runaway and hit the cutoff switches within 4 seconds in order to be able to manually re-trim the plane in a timely manner (at the specific altitude of the second flight? [EDIT: or just to still be able to overcome the mechanical resistance on the trim wheels?]). Too short given the number of distracting alarms, stick shakers etc.
- In a filmed simulator run of the second crash with a pair of instructors, it was physically impossible for the copilot to mechanically re-trim the plane due to aerodynamic forces on the elevator. The re-engaging of the cutoff switches appeared to be a last ditch dice throw once they were unable to mechanically unable to manually re-trim the plane and were heading into the ground anyway.
As I say, taken from the documentary, but based on the flight recorder data and Sim.
-
https://www.youtube.com/watch?v=vV_o9kTRXUY (https://www.youtube.com/watch?v=vV_o9kTRXUY)
-
It seems that Canadians are keeping a cool head and suggesting to sudo rm -rf MCAS
There are some (including me) who find that the exact opposite of keeping a cool head and acting fully rationally on facts and data. Maybe there’s no way for MCAS to be safe, but given the long successful history on Boeing aerial refueling tankers, I suspect there is a way. To close your mind to that possibility seems unusual and suboptimal, if not outright improper, for a regulator.
-
I wonder how many months of grounding are equivalent to the cost 737 Max saved on pilot training by introducing MCAS as a hidden feature in the first place.
PS. was MCAS a documented feature on the military planes?
-
I wonder how many months of grounding are equivalent to the cost 737 Max saved on pilot training by introducing MCAS as a hidden feature in the first place.
PS. was MCAS a documented feature on the military planes?
Both Boeing and the carriers affected must be in deep negative territory at this point when compared to the upfront spreadsheet savings management calculated when they made the sales pitch to American Airlines.
-
Maybe there’s no way for MCAS to be safe, but given the long successful history on Boeing aerial refueling tankers, I suspect there is a way.
While I agree with you in principle, my emotive side says "Yeah, but would you ever trust it?". Remember you are trusting both the system to "do the right thing" and the guys in the big hats up the front to recognise when it's "not doing the right thing" and knobling it before it (to mis-use a Billy Connolly quote) "sends it into the ground like a fucking dart".
Both of those elements have failed simultaneously twice now. They may (mostly) fix the first one, but given the poor training dished out in some of these schools/airlines I'm not sure I can be confident of the second.
-
I could be wrong.
1. The MCAS used in some military planes is not broken/flawed the way the one on the MAX was.
IIRC, the MCAS on the refuelling tanker plane relies on multiple AOA sensors.
2. Military planes have a different level of acceptable risk/redundancy
3. MAX trim adjustment system was not designed to handle the aerodynamics produces by the engine change. The MAX pushes the limits of what the plane's control system can achieve at its extreme limits and and still fly straight. This is very serious, because it means a loss of redundancy. If MAX is wrong, the pilots may not be able to undo the result of this faulty MAX by using the redudant/backup trim adjustment system.
4. Regarding the Canadian official comment, about removing MAX, completely; Sokoloff has stated that the MAX is likely not certifiable, at all, without MCAS, no matter how much additional training is provided to the pilots.
This last bit is curious. The American media has since the beginning made it out to sound like MCAS was a convenience item to make the plane more like the previous plane to reduce pilot workload, or something to that effect. To reduce training costs. This may have essentially been spin doctoring or damage control.
Considering the flight record of the MAX to date, it is conceivable that some tweaks to MCAS will make the plane statistically fine. But the reputation problem may be too big to overcome. The FAA was also exposed by these disasters, so there's no one left to say "safe now" and be taken seriously. This MAX will perhaps have to go through multiagency endorsement. The regulatory bodies in EU for instance may not like MCAS and they may be loathe to put their endorsement on it, but they also feel the pressure of getting these planes back in the air rather than turning into a gigantic IOU from Boeing that may never get paid.
Could Boeing go bankrupt?
-
I could be wrong.
... stuff I applied the previous statement to ...
Could Boeing go bankrupt?
We are in agreement.
COULD (point at any business) go bankrupt? The answer is YES. Not my fault you asked a silly question. Is it likely to? Different question.
Remember bankruptcy in a business the size of Boeing is usually more of a cash-flow crisis, and is almost never an actual going-out-of-business situation. The results of which range from "never mind" (after having frozen things in legal limbo for a while) to making partial payments to creditors in the interest of maintaining the industry and/or getting bailed out by the government. In any case, since it's the stockholders that usually get screwed the most in the latter case, you can use wall street to judge the odds of it happening in the first place.
-
4. Regarding the Canadian official comment, about removing MAX, completely; Sokoloff has stated that the MAX is likely not certifiable, at all, without MCAS, no matter how much additional training is provided to the pilots.
I am not a Boeing insider, but I believe that Boeing took the MCAS route by virtue of the unmodified airplane being unable to meet the requirements of FAR §25.173 (https://www.law.cornell.edu/cfr/text/14/25.173). I don't see any reason to think that a properly implemented/modified MCAS would not be certifiable.
This not a requirement that you can waive by pilot training. MCAS was not just a convenience / similarity to other airframes feature.
-
https://www.youtube.com/watch?v=S6dMlbCPmX0
Blanco Lirio channel from Aug30
If you start the vid at 3:25, it seems this is circular logic to prevent calling a spade a spade. If you have time, just listen from 3:25 onward for about a minute or 3. It's quite impressive.
"MCAS is ONLY there to make the plane behave like previous models. The plane is stable, because it meets FAR 25. FAR 25 is important so that the plane will behave predictably. The MAX does not behave correctly in two spots which are pretty important; namely high speed stall and low speed stall. So basically anywhere that the feel of the controls is especially important. So MCAS is added to fix this. Only to make the MAX behave like other 737's, not because it doesn't meet stability requirements of FAR 25. Now are you 100% confident?"
It seems like regulatory body red tape and doublespeak is replacing engineering either for legal reasons or an attempt to avoid public scare from key buzz words. It would be more reassuring if the industry PR's kept to logic.
;;;;;;;;;;;;;;;;
I've been mixed up a few times, before. But my current understanding, to date:
It sounds like Boeing added MCAS to make the control feedback feel right at normal cruising speed. Then they increased it 3-4 fold after finding out that at lower speed you need even more angle for the controls to feel right. Basically, that stunt that Airbus pulled with one of their planes, by doing the "low and slow" in front of a live press audience? If the plane were a 737 Max without MCAS, it wouldn't necessarily have crashed. But the pilot may have declined to perform it in the first place, not feeling it was safe to do on purpose. Esp so low, forcing him to distribute his attention across multiple variables while having less than ideal feedback on the control column. :-// I hope this is right. And no it doesn't sound terrible, as long as this part of the AOA envelope is fairly extreme and unlikely to ever be utilized in the course of duty, and even if, probably not intended to remain in this state for long.
-
"MCAS is ONLY there to make the plane behave like previous models. The plane is stable, because it meets FAR 25. FAR 25 is important so that the plane will behave predictably. The MAX does not behave correctly in two spots which are pretty important; namely high speed stall and low speed stall. So basically anywhere that the feel of the controls is especially important. So MCAS is added to fix this. Only to make the MAX behave like other 737's, not because it doesn't meet stability requirements of FAR 25. Now are you 100% confident?"
Your quotation/transcription is sufficiently inaccurate as to be misleading, IMO.
"We also want to clear up some common misconceptions that were initially promulgated by the mainstream media and spread through social media like wildfire by folks that really don't understand some of the basics about aircraft stability in aviation. Those basic misconceptions are this. One, the MCAS is an anti-stall system. I see/hear this all the time on media reports. The MCAS is not an anti-stall system. The pilots of Boeing designed aircraft are the ultimate anti-stall system. MCAS is a means to provide the pilots the control feel inputs that they need to recognize an impending stall and recover from it. The other common misconception is that the 737 is an inherently unstable aircraft because of the design change, the bigger engines. No, the 737 is not an unstable aircraft; it cannot be an unstable aircraft as per the FAR FAA design requirements for basic transport category aircraft stability. MCAS is not installed in the 737 Max to meet the requirements of FAR Part 25.171 ("Aircraft Stability")."
I think that everything he said there is correct.
Right after that though, he starts to wade into territory where he's saying things that are not backed by facts and range from opinion to likely misleading/false statements.
"Again, what MCAS is all about is an effort to get the new 737 Max to handle and feel like previous iterations of the 737 so that all of these aircraft can be operated on a single type certificate [sic] rating."
Confusing a type certificate with a type rating and opining about whether this is all about control feel and money without acknowledging that though the aircraft meets 25.171, it fails something in 25.173 or 25.175 is also misleading, IMO.
-
I also think that's just some flight instructor with a YouTube channel, not a Boeing spokesperson to my knowledge. (No way does counsel let him talk gibberish like the second part of that if he's in an official capacity.)
-
^Yeah, but he is a commercial pilot. Like Mentour Pilot. If these guys waded very far from their employers' agendas, they would probably hear about it.
I completely understand everything he said. Taken individually, each statement can be interpreted in a way that it is true, by itself. It just doesn't connect the way he suggests. It's like a big circular non sequitur, and it offends my brain to consider this video logical or illuminating. It's skirting around important legal issues, which is perfectly reasonable. There's no way these guys are going to put their jobs and reputations on the line to go there and make statements that could be used to point blame. But it's... disingenuous. That's the word. Or maybe you could call it PR or lawyer speak.
-
I also think that's just some flight instructor with a YouTube channel, not a Boeing spokesperson to my knowledge. (No way does counsel let him talk gibberish like the second part of that if he's in an official capacity.)
He's never claimed to be a spokesman for anyone, just a citizen reporter. He occasionally goes through his aviation history in videos, but I'm not going to hunt one down for you. Short story is he flew for the military, mostly large transport aircraft, then transitioned to civilian airline pilot decades ago. He identifies his employer as a large major airline in videos (open secret that it's American Airlines, however), and has many thousands of hours and type ratings in many of the aircraft they fly or flew, including the 737. His current gig is in the 777. Bottom line, he's far more qualified to opine than 99.9% of the people in this thread, including those of us who are some kind of pilot. Here's a short video from his day job that was easy to find. The caption in the youtube description is:
HKG-LAX 35,000. '84 Mach
A short clip from my day job...
https://www.youtube.com/watch?v=5s_VeOhiOr4 (https://www.youtube.com/watch?v=5s_VeOhiOr4)
-
"Boeing considers suspending or halting 737 Max production"
https://www.theguardian.com/business/2019/dec/16/boeing-737-max-production-faa (https://www.theguardian.com/business/2019/dec/16/boeing-737-max-production-faa)
On Thursday, Boeing abandoned its goal of winning approval this month to unground the 737 Max after its chief executive, Dennis Muilenburg, met FAA administrator Steve Dickson. Dickson said on Wednesday he would not clear the plane to fly before 2020 and disclosed the agency had an ongoing investigation into 737 production issues in Renton, Washington.
Dickson said there were nearly a dozen milestones that must be completed before the Max returns to service. Approval is not likely until at least February and could be delayed until March, US officials told Reuters last week.
-
This was to be expected.
That's gotten really bad for Boeing. How are they going to get out of this?
-
[...]
How are they going to get out of this?
By spending the time, care, attention, and professionalism that they didn't muster the first time round. They cannot regain trust any other way.
-
I don't think many people will want to fly in a 737 MAX never more. I would not want.
-
This was to be expected.
That's gotten really bad for Boeing. How are they going to get out of this?
Bribe FAA a bit more?
-
They don't need to bribe FAA. FAA and Boeing are in the same bed at this point. They both need to regain public trust. If FAA rushed and made another mistake, then it would be a real problem. So far it seems like Boeing stock is going along fine. Increase in executive bonuses this year for the good job in fixing MAX?
It seems like some kinda noise in the press and social media when people eventually start seeing "Boeing MAX" on their tickets is unavoidable, at this point. It's not like the old days when we had just live TV broadcast. So I think there is still some sort of PR challenge ahead.
I don't think many people will want to fly in a 737 MAX never more. I would not want.
If I were given a choice, I would certainly feel strange choosing a MAX, even if the statistics say it is safer than walking and chewing gum. But a choice between a direct flight on a MAX or a layover might be all it takes? I wonder how many people flew on a MAX before the grounding who don't even realize it? I didn't pay attention to plane models, before. I think confidence in Boeing's credit line will get people back on the planes. Heck, if Boeing is going to pay my family million dollars for my death, maybe I'll sign up for the first flight.
-
It's a whole new level scary :(
Shutdown likely (https://www.seattletimes.com/business/boeing-aerospace/shutdown-likely-at-boeing-renton-as-737-max-crisis-extends/) for 12,000 employees in the region. A lousy Christmas for them and suppliers too.
FAA probes 737 MAX production (https://www.reuters.com/article/us-boeing-airplane-idUSKBN1YF18G?)
"The manager, Ed Pierson, drew a link between faulty Angle of Attack sensors in two recent 737 MAX crashes that killed 346 people and what he called a “chaotic and alarming state” inside Boeing’s factory that undermined quality and safety.
“It is alarming that these sensors failed on multiple flights mere months after the airplanes were manufactured in a factory experiencing frequent wiring problems and functional test issues,” Pierson said at the hearing.
“I witnessed a factory in chaos,” he said. "
Boeing removed copper ground straps (https://www.seattletimes.com/business/boeing-aerospace/faa-engineers-objected-to-boeings-removal-of-some-787-lightning-protection-measures/) in the 787's fuel tanks... carbon fiber I guess lightning arcs across fasteners in the fumes, so they added a nitrogen gas system. Just silly complicated stupid way to save bucks on safety.
-
They don't need to bribe FAA. FAA and Boeing are in the same bed at this point. They both need to regain public trust. If FAA rushed and made another mistake, then it would be a real problem. So far it seems like Boeing stock is going along fine. Increase in executive bonuses this year for the good job in fixing MAX?
It seems like some kinda noise in the press and social media when people eventually start seeing "Boeing MAX" on their tickets is unavoidable, at this point. It's not like the old days when we had just live TV broadcast. So I think there is still some sort of PR challenge ahead.
I don't think many people will want to fly in a 737 MAX never more. I would not want.
If I were given a choice, I would certainly feel strange choosing a MAX, even if the statistics say it is safer than walking and chewing gum. But a choice between a direct flight on a MAX or a layover might be all it takes? I wonder how many people flew on a MAX before the grounding who don't even realize it? I didn't pay attention to plane models, before. I think confidence in Boeing's credit line will get people back on the planes. Heck, if Boeing is going to pay my family million dollars for my death, maybe I'll sign up for the first flight.
So you will give your life just for the "fiats" printed by FED? :o
They have been in beed for a long time but now neither side wants to sleep on the wet cold spot on the beed sheet.
Its about optics, what the dumbed down public is gonna be exposed to, a crash is difficult to cover up for so the optics are adjusted dependent on the things need to be covered up in the aftermath.
Well,apparently 787 workers dont want to fly on what they build. :-//
https://www.eevblog.com/forum/chat/boeing787-a-motherfucker!(words-from-boeing-assembler)/ (https://www.eevblog.com/forum/chat/boeing787-a-motherfucker!(words-from-boeing-assembler)/)
-
It's a whole new level scary :(
Shutdown likely (https://www.seattletimes.com/business/boeing-aerospace/shutdown-likely-at-boeing-renton-as-737-max-crisis-extends/) for 12,000 employees in the region. A lousy Christmas for them and suppliers too.
and airlines using 737, they all made plans expecting to get new planes and made contracts to sell off old planes etc.
-
It's a whole new level scary :(
Shutdown likely (https://www.seattletimes.com/business/boeing-aerospace/shutdown-likely-at-boeing-renton-as-737-max-crisis-extends/) for 12,000 employees in the region. A lousy Christmas for them and suppliers too.
FAA probes 737 MAX production (https://www.reuters.com/article/us-boeing-airplane-idUSKBN1YF18G?)
"The manager, Ed Pierson, drew a link between faulty Angle of Attack sensors in two recent 737 MAX crashes that killed 346 people and what he called a “chaotic and alarming state” inside Boeing’s factory that undermined quality and safety.
“It is alarming that these sensors failed on multiple flights mere months after the airplanes were manufactured in a factory experiencing frequent wiring problems and functional test issues,” Pierson said at the hearing.
“I witnessed a factory in chaos,” he said. "
Boeing removed copper ground straps (https://www.seattletimes.com/business/boeing-aerospace/faa-engineers-objected-to-boeings-removal-of-some-787-lightning-protection-measures/) in the 787's fuel tanks... carbon fiber I guess lightning arcs across fasteners in the fumes, so they added a nitrogen gas system. Just silly complicated stupid way to save bucks on safety.
Nitrogen and other fuel tank inerting systems have been required on apparently most airliners since 2008. As the article you link says, the nitrogen system was one of the three remaining safety components. So ALL 787s have it, not just the ones without the copper foil! Read carefully, mmkay? ;)
-
A shut-down of the 737 MAX production line is in the wind.... Will it happen?
https://www.youtube.com/watch?v=8HVnhrCM4Pk (https://www.youtube.com/watch?v=8HVnhrCM4Pk)
-
Boeing have still been making the MAX (though since the grounding they've reduced production by about 20%) - which begs the question: Where do you put them all?
Answer: Wherever they can find the space. (They can still be flown - but ONLY to a "parking" destination.)
(https://www.eevblog.com/forum/chat/lion-air-crash-jakarta-boeing-737-had-prior-instrument-error/?action=dlattach;attach=890906;image)
(That did make me smile)
-
Boeing could take 10 of these MAX planes sitting in parking lots, and loan them out.
... to stunt pilots they sponsor to put on air shows, doing dare-devil stuff.
Bad taste? Definitely. I still want to see it. And (as long as they could perform some cool stuff in close formation and don't crash, fingers crossed) that would instill some confidence to me, in the least. It's irrational, but seeing is believing.
-
How are they going to get out of this?
By spending the time, care, attention, and professionalism that they didn't muster the first time round. They cannot regain trust any other way.
Have doubt if Boeing will prioritize that path 1st, as it will take too much time and will piss off the share holders big time.
Only smart & quick maneuvering will help, and imo this already started, like the action on increasing the pressure at Airbus thru international tariff war, which is quite successful as WTO basically punished Airbus (EURO).
Next step is to do similarly to what NRA have been done for decades at the US senates, not very sure how this move extend to, maybe declare or campaigning "nationalism" by pressuring US airlines not to buy Airbus for initial stage ?
Or if the current administration shows a big chance will get elected in 2020, just give a fair share to one of the POTUS's family member and give a seat at the board of directors, this will be an "ideal" case as the orange dude is one of the best salesman on earth, and also has an ideal leveraging power on this matter internationally.
Yeah, I'm dreaming. :-DD
-
... Boeing removed copper ground straps (https://www.seattletimes.com/business/boeing-aerospace/faa-engineers-objected-to-boeings-removal-of-some-787-lightning-protection-measures/) in the 787's fuel tanks... carbon fiber I guess lightning arcs across fasteners in the fumes, so they added a nitrogen gas system. Just silly complicated stupid way to save bucks on safety.
Nitrogen and other fuel tank inerting systems have been required on apparently most airliners since 2008. As the article you link says, the nitrogen system was one of the three remaining safety components. So ALL 787s have it, not just the ones without the copper foil! Read carefully, mmkay? ;)
I didn't know aluminium-body aircraft first got nitrogen gas "inerting system" in the fuel tanks, I thought it was only newer for carbon-fiber bodies. Lightning can't generate arcs inside a metal fuel tank as a Faraday cage.
It was the fuel tank level-sensor as an ignition source, implicated in TWA Flight 800's (https://en.wikipedia.org/wiki/TWA_Flight_800) center tank explosion, that changed the rules and caused a fiasco for existing aircraft.
Carbon-fiber fuel tanks introduce a new risk but what's a little arcing inside the tank between fasteners...
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 120-98A.pdf (https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 120-98A.pdf)
-
I didn't know aluminium-body aircraft first got nitrogen gas "inerting system" in the fuel tanks, I thought it was only newer for carbon-fiber bodies. Lightning can't generate arcs inside a metal fuel tank as a Faraday cage.
It was the fuel tank level-sensor as an ignition source, implicated in TWA Flight 800's (https://en.wikipedia.org/wiki/TWA_Flight_800) center tank explosion, that changed the rules and caused a fiasco for existing aircraft.
Carbon-fiber fuel tanks introduce a new risk but what's a little arcing inside the tank between fasteners...
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 120-98A.pdf (https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 120-98A.pdf)
Not just carbon fiber planes/tanks:
http://www.aero-news.net/index.cfm?do=main.textpost&id=4b9ea1a9-bfd6-4967-9ee9-6d6c47298243 (http://www.aero-news.net/index.cfm?do=main.textpost&id=4b9ea1a9-bfd6-4967-9ee9-6d6c47298243)
-
Perhaps not just the MCAS system at fault. Boing pilot talking aboyt thrust control systems going berserk as well.
https://youtu.be/skbUDZb1Ybs
-
If the auto throttle software doesn't work because it's been overridden by something else that takes higher priorty then it's no wonder you can't manually trim the aircraft. Maybe a lot of pilots are used to the auto throttle doing it for you and intuitively wouldn't know what to do if the automation failed because they have zero hours flying manually. Automation for the most part is there to make the pilots job easier but when it doesn't work and you don't have enough hours flying manually then accidents happen.
Talking of thrust control systems going berserk
, Boeings Starliner just did the same thing but they got it home in the end.
-
https://www.space.com/boeing-ceo-muilenburg-resigns.html (https://www.space.com/boeing-ceo-muilenburg-resigns.html)
-
https://www.space.com/boeing-ceo-muilenburg-resigns.html (https://www.space.com/boeing-ceo-muilenburg-resigns.html)
Yep. I thought it would have happened earlier.
And now what... is Boeing going to also change names? ::)
-
I've seen many times a scumbag CEO cause irreparable damage to a corporation's culture, ethics and values. It takes years to turn it around, if even possible. Some companies never recover.
It's strange Muilenburg is an engineer but sure didn't show it, on any level. His replacement Calhoun's background is finance/marketing, yup sure he can turn things around :palm:
-
^If he is a good listener/leader, the background is perhaps not super critical at that level.
-
Who's going to stick out their neck and speak for safety with added costs, and risk losing their aerospace career? It's going to be hack and slash cuts until the 737 Max flies again.
-
He probably left with a big fat package on top of his 30mil a year salary.
-
He probably left with a big fat package on top of his 30mil a year salary.
but the emotional pain...
-
He probably left with a big fat package on top of his 30mil a year salary.
but the emotional pain...
Don't forget that CEO's have much higher rates of psychopathy than general public. Whether this is the case here is unknown, but it's fairly likely they are just fine despite being a part of killing people by negligence. If this wasn't the case, he would have likely left ages ago, or not taken the task at all.
-
He probably left with a big fat package on top of his 30mil a year salary.
but the emotional pain...
Don't forget that CEO's have much higher rates of psychopathy than general public. Whether this is the case here is unknown, but it's fairly likely they are just fine despite being a part of killing people by negligence. If this wasn't the case, he would have likely left ages ago, or not taken the task at all.
I was talking about the emotional pain coming from losing his highly paid position.
Of course lower levels of emotional empathy (closing to psychopathy) is to be expected of such positions.
-
Dennis Muilenburg is a psychopath, evidenced in the congressional hearing. He showed zero emotions and it was so bad that the families of the dead were scolding him and instructing him on the emotions he is missing. Just terrible to watch.
His golden parachute is expected to total around $60M. It seems surreal the guy does billions of dollars damage, hundreds killed and he gets to walk and live a rich life. CEO is a preferred job for the psychopath. (https://en.wikipedia.org/wiki/Psychopathy_in_the_workplace)
-
No one serves jail time, that is the main point of what the fuss all about. >:D
Imagining that Boeing is a Chinese company, and Dennis is a Chinese citizen working in China ...
-
https://www.space.com/boeing-ceo-muilenburg-resigns.html (https://www.space.com/boeing-ceo-muilenburg-resigns.html)
So what is it, resigns or was fired?
https://en.wikipedia.org/wiki/Dennis_Muilenburg (https://en.wikipedia.org/wiki/Dennis_Muilenburg)
"He was CEO from July 2015 until December 23, 2019, when he was fired after the aftermath of the two crashes of the 737 MAX"
"Boeing Fires C.E.O. Dennis Muilenburg"
https://www.nytimes.com/2019/12/23/business/Boeing-ceo-muilenburg.html (https://www.nytimes.com/2019/12/23/business/Boeing-ceo-muilenburg.html)
-
https://www.space.com/boeing-ceo-muilenburg-resigns.html (https://www.space.com/boeing-ceo-muilenburg-resigns.html)
So what is it, resigns or was fired?
https://en.wikipedia.org/wiki/Dennis_Muilenburg (https://en.wikipedia.org/wiki/Dennis_Muilenburg)
"He was CEO from July 2015 until December 23, 2019, when he was fired after the aftermath of the two crashes of the 737 MAX"
"Boeing Fires C.E.O. Dennis Muilenburg"
https://www.nytimes.com/2019/12/23/business/Boeing-ceo-muilenburg.html (https://www.nytimes.com/2019/12/23/business/Boeing-ceo-muilenburg.html)
Boeing's press release stated that, "The Board of Directors decided that a change in leadership was necessary to restore confidence in the Company moving forward as it works to repair relationships with regulators, customers, and all other stakeholders."
That sounds like a sacking to me. You can't fire me, I quit!
-
It is common practice that the board want's to fire a manager, but instead of a formal dismissal they ask the manager to resign. So formally the manager resigns to avoid getting fired.
-
The CEOs of today's large corporations are selected and hired by the Boards in the same manner and for the same reason as the actors are selected and assigned for the John McClane role in the "Die Hard X" movie. The job of the Board is to communicate towards the Markets the new John McClane will save the World, thus all the Markets will react positively. Such a role costs and the CEO's contract reflects that.
-
The CEOs of today's large corporations are selected and hired by the Boards in the same manner and for the same reason as the actors are selected and assigned for the John McClane role in the "Die Hard X" movie. The job of the Board is to communicate towards the Markets the new John McClane will save the World, thus all the Markets will react positively. Such a role costs and the CEO's contract reflects that.
The reason it took so long to let the CEO go, might have been that it takes time to find a good "actor" to take on a tough role with a complicated script.
-
The CEOs of today's large corporations are selected and hired by the Boards in the same manner and for the same reason as the actors are selected and assigned for the John McClane role in the "Die Hard X" movie. The job of the Board is to communicate towards the Markets the new John McClane will save the World, thus all the Markets will react positively. Such a role costs and the CEO's contract reflects that.
Exactly. They serve no other purpose really. They even have little (if any) operational role. They're mostly just a name and image. Sure they make craptons of money while it lasts (and also when they get fired, which is an integral part of the job), but they are mainly selling their name, not their work (as most other employees would). Changing CEOs when things go wrong is inevitable, but it obviously doesn't solve anything.
Sure there are a few exceptions but usually mostly CEOs that were also among the company's founders or close relatives.
And of course here "resign" or "fired" doesn't matter. CEOs are not common employees. It's just the same. It's just like for people with the higher political functions. The official take is alwats they "resigned", so as to keep both the person's professional image intact AND the image of the position (and that of the people above) as well!
-
https://www.youtube.com/watch?v=PlaMQBEg-9M (https://www.youtube.com/watch?v=PlaMQBEg-9M)
-
This was mentioned in The Keiser Report, about 8 mins in, sounded a bit tongue in cheek, comparing with financial algorithms. :o
https://youtu.be/vfazTPircVw?t=617
-
No one serves jail time, that is the main point of what the fuss all about. >:D
Imagining that Boeing is a Chinese company, and Dennis is a Chinese citizen working in China ...
So you suggesting he would been shoot, hanged then killed and chopped up in pieces then his organs been taken out for donation to top elites of the party while blamed for being a Falungong activist? No China isnt fascistic like psychopath Muillenburg and US justice system? No cant be.
The CEOs of today's large corporations are selected and hired by the Boards in the same manner and for the same reason as the actors are selected and assigned for the John McClane role in the "Die Hard X" movie. The job of the Board is to communicate towards the Markets the new John McClane will save the World, thus all the Markets will react positively. Such a role costs and the CEO's contract reflects that.
Which suggests not only are the board who selects CEO's and the Market who reacts to their decisions a bunch of psychopaths.
-
There's simply no end to this...
https://aviationweek.com/air-transport/boeing-fought-lion-air-proposed-max-simulator-training-requirement
-
He probably left with a big fat package on top of his 30mil a year salary.
but the emotional pain...
Don't forget that CEO's have much higher rates of psychopathy than general public. Whether this is the case here is unknown, but it's fairly likely they are just fine despite being a part of killing people by negligence. If this wasn't the case, he would have likely left ages ago, or not taken the task at all.
It's not just the board that pushes for sociopath types, the investor community (Wall Street, the Banking industry and the wealthy), the folks with the real clout, want a CEO that will have no problems closing a factory in one country in order to move production to cheaper places and a sociopath/psychopath is just more amenable to laying-off thousands of workers to do so. This is the era we live in and it's an era that the charts show began to have the desired effect around about 1973.
https://www.reddit.com/r/LateStageCapitalism/comments/7vsicm/the_most_important_graph_income_vs_productivity/ (https://www.reddit.com/r/LateStageCapitalism/comments/7vsicm/the_most_important_graph_income_vs_productivity/)
For thousands of years before the industrial revolution the average workers income barely moved and remained at near poverty levels, then, as the industrial revolution kicked in the standard of living for the middle class increased and did so quite dramatically. You can slice it many different ways, but what the industrial revolution really was was the application of science and technology to decrease unit cost and improve unit quality. And, as productivity increased so did workers wages and standard of living. However, when the investor class realized they could make far more money by cutting the workers out of there share of profits and the rules changed to permit it, then we had that inflection point about 1973 and workers incomes have flat-lined or trended down every since. If workers had been cut out of a share of profits that productivity gains provided since the beginning of the industrial revolution there would never have been an industrial revolution because the buying power of the middle class would not have risen and the volume of production would never have increased. I'm approaching my mid 60's and every day of my working life, now closing in on 45 years, has been in this era -- I've never known anything else.
Younger workers can point at 'boomers' as the root cause but that like blaming all white people for the sins of the few in power. Most boomers of my age will not be able to retire with the same comfort level, or at all, as older boomers who timed there exit a bit better so it's not just younger workers that have been shit on.
When politics is driven by money and the wealthy are permitted outsized influence then it should come as no surprise that, over time, we'd get to where we are. We've been in a de-regulation phase since right about the inflection point and no where is the consequence of this more apparent than the Boeing/FAA situation of the 737MAX.
What Boeing became is what most others companies have become.
Brian
-
If workers had been cut out of a share of profits that productivity gains provided since the beginning of the industrial revolution there would never have been an industrial revolution because the buying power of the middle class would not have risen and the volume of production would never have increased.
An example is Brit colonization of India. For some 60 years under British colonialism, India traded at a surplus but ended with a financial deficit. India benefited from law and order and culture and technology. But most of their profits were enjoyed by Britain. Not that certain individuals in India didn't profit, massively. (Not all that different from how Saudi Arabia enriches certain individuals in America in order for this club to massively profit at the expense of America's economy. The average Saudi citizen is a baller, but without this arrangement, Iran would come and take their lunch box).
There is actually nothing wrong with this system. It's how society advances. Slavery and/or disaparity in income is necessary. We don't have a better way. It doesn't exist. Communism is the same thing, only the ruling class will inevitably need to use excessive force and restrictions of freedom to maintain this order. In communism, you are born to the ruling class like nobility, and you sit in a room deciding what your peasants do and how to punish them. In capitalism, whoever has the money has the responsibility to protect their own and their peasants interests (and these people have the ability to lose all this money, too).
If your country shares better and is happy, it's not for long. Cuz the country that does not will have a bigger club and will take that tribute that your country was not collecting from its people to use for such things. The idea is for the wealthy to have its best interests aligned better with the peasants. Like a big protection racquet.
I think US is far from the worst to its peasants, and is one of the the least racist first world countries, IMO. Not that it's great, but there's lots worse.
People might look at Switzerland and say it's a peaceful country. The history behind that is that Swiss have strong geographical defenses and were historically very successful mercenaries. The regional European powers mutually agreed to leave Switzerland alone, otherwise if Switzerland takes a side, the other power would have to get their merc from somewhere else.
Sorry to get so far off topic.
-
If workers had been cut out of a share of profits that productivity gains provided since the beginning of the industrial revolution there would never have been an industrial revolution because the buying power of the middle class would not have risen and the volume of production would never have increased.
An example is Brit colonization of India. For some 60 years under British colonialism, India traded at a surplus but ended with a financial deficit. India benefited from law and order and culture and technology. But most of their profits were enjoyed by Britain. Not that certain individuals in India didn't profit, massively. (Not all that different from how Saudi Arabia enriches certain individuals in America in order for this club to massively profit at the expense of America's economy. The average Saudi citizen is a baller, but without this arrangement, Iran would come and take their lunch box).
There is actually nothing wrong with this system. It's how society advances. Slavery and/or disaparity in income is necessary. We don't have a better way. It doesn't exist. Communism is the same thing, only the ruling class will inevitably need to use excessive force and restrictions of freedom to maintain this order. In communism, you are born to the ruling class like nobility, and you sit in a room deciding what your peasants do and how to punish them. In capitalism, whoever has the money has the responsibility to protect their own and their peasants interests (and these people have the ability to lose all this money, too).
If your country shares better and is happy, it's not for long. Cuz the country that does not will have a bigger club and will take that tribute that your country was not collecting from its people to use for such things. The idea is for the wealthy to have its best interests aligned better with the peasants. Like a big protection racquet.
I think US is far from the worst to its peasants, and is one of the the least racist first world countries, IMO. Not that it's great, but there's lots worse.
People might look at Switzerland and say it's a peaceful country. The history behind that is that Swiss have strong geographical defenses and were historically very successful mercenaries. The regional European powers mutually agreed to leave Switzerland alone, otherwise if Switzerland takes a side, the other power would have to get their merc from somewhere else.
Sorry to get so far off topic.
Yes systems are still quite compact but the society is not advancing and that is the real reason of today's worst condition of most of the countries.
-
Hi,
This is a great thread....i read it, and all on google, but can anyone answer three questions...
1.... Why didnt the pilots put the plane into manual mode and land it at the nearest airport after they started having significant problems?
2...What exactly was the fault with the angle of attack sensor?
3...Regarding software failure systems in passenger aircraft...how many other ones are unknown to pilots other than EMACs used in 737 MAX?...ie, is this the first time in aviation history that a software system instigated a fault that caused death and the pilots never even knew about the particular software system and it characteristics? (ie like they never knew about EMACs in the 737 MAX)
-
1.... Why didnt the pilots put the plane into manual mode and land it at the nearest airport after they started having significant problems?
Well, there's no "manual mode". The instructions for runaway elevator trim is to turn off the computer-controlled elevator trim, but that also
shuts off the trim buttons on the control column. Then, you have to trim the trim wheel by hand. If you are already fighting extreme control forces due to mis-trimming of the elevator/stabilizer, you may not be able to take your hands off the column -- you need all 4 arms to counteract the control forces.
The problem is that the old software (not revealed to the pilots in the flight manual) wound continue to apply more nose-down trim every nine seconds, leading to ever increasing control forces, unless the pilot immediately applies a LONG countering nose-up trim. The crash pilots didn't counter the nose-down trim with a long-enough nose-up trim. So, the control forces became heavier and heavier with each repeat of the sequence.
2...What exactly was the fault with the angle of attack sensor?
These are easily damaged when moving air bridges and trucks around the aircraft. Apparently, the replacement sensor was improperly installed at the wrong angle, even though the bolt holes are designed to prevent this. One sensor apparently indictaed something like 40 degrees nose-up as soon as the aircraft started moving. Due to the airlines not wanting to permit ANY additional training for pilots moving to the Max, the flight control computers were set up to use ONLY ONE sensor at a time, depending on which FCC was the master. So, even though the aircraft had two sensors, it only looked at one or the other. There was no "alpha disagree" warning, even though the info was available to the computers. The reason was "that would require a change to the flight manual" which the airlines did not want.
3...Regarding software failure systems in passenger aircraft...how many other ones are unknown to pilots other than EMACs used in 737 MAX?...ie, is this the first time in aviation history that a software system instigated a fault that caused death and the pilots never even knew about the particular software system and it characteristics? (ie like they never knew about EMACs in the 737 MAX)
Nope, not even close to the first time. The Airbus A400M military aircraft took off with no calibration data loaded into the engine computers. This caused all 4 engines to shut off in the air, causing a crash. It seems the engine computers should have been programmed to do something rational, such as not even start, or not allow the engines to be advanced beyond ground idle.
I doubt these are the only cases.
Jon
-
Oh, another one I've heard of, not passenger plane, though. A flight of F-16 jets crossed through the international date line. All the aircraft immediately flipped upside down. There was a bug in the inertial reference software that dealt with which side of the earth you were on. This was quite some time ago.
Jon
-
Nope, not even close to the first time. The Airbus A400M military aircraft took off with no calibration data loaded into the engine computers. This caused all 4 engines to shut off in the air, causing a crash. It seems the engine computers should have been programmed to do something rational, such as not even start, or not allow the engines to be advanced beyond ground idle.
I doubt these are the only cases.
Deciding on the 'sensible' action to take with no data is not an easy question to answer. When a Qantas A380 (Qantas flight 32) had an uncontained engine failure in the number 2 engine (left side, inboard), it severed communications to the #1 engine (outboard). The engine's default was to "continue to do what you were last told", which at the time was initial climb power (likely 80-90ish %). When they landed the aircraft, they had to do so with one engine at close to takeoff power, and it required all 4000m of WSSS/SIN's runway to stop the aircraft. The fire department had to foam the engine for a considerable period of time to shut it down, and there was a conversation something like "Can you please shut down #1" from the FD and "It isn't?" from the pilots
-
These are easily damaged when moving air bridges and trucks around the aircraft. Apparently, the replacement sensor was improperly installed at the wrong angle, even though the bolt holes are designed to prevent this. One sensor apparently indictaed something like 40 degrees nose-up as soon as the aircraft started moving. Due to the airlines not wanting to permit ANY additional training for pilots moving to the Max, the flight control computers were set up to use ONLY ONE sensor at a time, depending on which FCC was the master. So, even though the aircraft had two sensors, it only looked at one or the other. There was no "alpha disagree" warning, even though the info was available to the computers. The reason was "that would require a change to the flight manual" which the airlines did not want.
IIRC the 2nd AOE sensor is actually an option, that not all airlines had opted for.
-
I just wonder why the not build some safty stuff into the System. Like when the lost the Link between the Cockpit and the Engine the Automatically power down (and get into a Idle Mode).
I would put some RF "emergency communication System in the hole Aircraft if a Wire connection fail (or all) the switch to an encrypt System who can control the Major Systems.
-
IIRC the 2nd AOE sensor is actually an option, that not all airlines had opted for.
No, they all have 2 sensors. One is normally being read by each flight computer, and the plane switches which computer is primary each takeoff. But, apparently, both sensors' data is available on the data bus to both computers. So, they COULD have compared the two sensors' readings.
The optional feature ($80,000) was a light and audible alarm for "AOA disagree". Few airlines ordered that option.
Jon
-
^Yeah, this seems like a bad thing.
Swapping flight computers/sensors every other flight seems sorta like using a plane with 200 live onboard as a computer/sensor tester. This only increases the chance of having a failure, and it reduces the MTF for the computer and the sensor.
Imagine if there are 1000 flight computers and sensors on there, and the plane rotates through them on each successive flight. Now your chances are way greater that you will have a fault on one of them. MTF for one computer/sensor might be 10 years, but now the MT for at least one or more to fail is like a matter of weeks.
"Darn. That computer/sensor worked perfectly fine, and everyone got back to the ground in one piece. Well, let's try the next one! All aboard!"
If the other set is a "backup" then there has to be some way to switch to it. In this case, there apparently isn't. AOA sensor malfunctioning? Just turn everything off, okey dokey, and use that wheel that doesn't turn.
Having two would be great, if they were both running in parallel, all the time. And the pilots could switch back and forth, instantly, anytime they wanted. Anything weird happening? Flip the switch and see if it doesn't go away.
-
^Yeah, this seems like a bad thing.
Swapping flight computers/sensors every other flight seems sorta like using a plane with 200 live onboard as a computer/sensor tester. This only increases the chance of having a failure, and it reduces the MTF for the computer and the sensor.
Yes, how the HELL this contraption got approved by the civil authorities in a bunch of countries is pretty hard to imagine. Boeing did conceal a bunch of stuff from the FAA, and they now have lots of egg on their face. The designated certification scheme really blew up on the Max.
Jon
-
I'm not an aviation engineer but it does leave me scratching my head as to why they'd decide to have two separate sensors but then not make some method of indicating a disagreement between the two as a standard feature. What's the point of redundancy if you're not going to detect a fault and alert the crew so they can act accordingly? It also strikes me as a very serious oversight that someone thought it was ok to make this MCAS system have so much authority that it could just keep pushing the nose down over and over beyond the ability of the flight controls to override. Surely there is some threshold where it should have been trivial for the software to determine "Ok we've pushed the nose down well beyond what we ever expect to need, something is probably wrong!"
-
I'm not an aviation engineer but it does leave me scratching my head as to why they'd decide to have two separate sensors but then not make some method of indicating a disagreement between the two as a standard feature. What's the point of redundancy if you're not going to detect a fault and alert the crew so they can act accordingly? It also strikes me as a very serious oversight that someone thought it was ok to make this MCAS system have so much authority that it could just keep pushing the nose down over and over beyond the ability of the flight controls to override. Surely there is some threshold where it should have been trivial for the software to determine "Ok we've pushed the nose down well beyond what we ever expect to need, something is probably wrong!"
I do agree with this. This was also my point right from the start, but I remember a few people replying to this that (IIRC):
- this was not as bad per se or as unusual as I thought;
- properly knowing what to do in case of sensors disagreement could be almost untractable;
- showing alerts was likely not a good idea, because overloading pilots with alerts was usually counter-productive.
(I probably forgot a couple other points.)
I do not agree with any of the above, but hey. YMMV. And for the 3rd point, there's a line between too little and too much.
As to adding a safety threshold as you suggested last - I also do agree, but it seems obvious (also from other discussions on related topics) that all this was just lacking in the written specifications for some reason, thus the developers just didn't implement any of this. Back to a discussion we had a while ago.
I'm still wondering why anyone at Boeing thought this system was so simple and so mundane that it didn't require any of these safety features. And not even any special training for the pilots. And not even any clear mention of its existence.
-
- properly knowing what to do in case of sensors disagreement could be almost untractable
I bet when the plane is actively trying to crash itself into the earth from less than 1000 feet, you would be willing to try the other one. I mean, the pilots were surely aware that the current setup was not working, correctly, even if they didn't have enough time to fully pinpoint the problem. Even without time to check out the "backup system," you would probably want to go with the odds of both "redundant" systems going screwy being relatively tiny. Esp when the odds of surviving the impending crash are going to be pretty close to nil.
This is like having a backup parachute that you don't pull, just in case it doesn't work. Well it's even worse. It's alternating parachutes on each jump, but when the one doesn't work, you give up on parachutes, altogether. Even though you carry two, and the other one worked fine on the previous jump.*
The arrangement they have made seems to be the opposite of redundancy. And is simply a doubling of the potential failure points.
*Boeing and/or FAA might not have considered the flight computer and AOA sensor (and w/e other stuff they are cleverly alternating/testing) to be as critical as a parachute. The plane may be very safe to fly without any of that, under most circumstances. But... whey carry and alternate between two "redundant" systems if you don't make them redundant?
edit: I suppose after regaining manual control of the plane, perhaps the pilots would attempt to boot up the backup computer/sensor? And having 2 AOA sensors, one would be able to know there's a disagree, even if an adverse event hadn't occurred, yet? I can see why using 2 AOA sensors will be helpful. But what's the point of alternating which one is the primary and which is the "ignored one?" i'd think after a sensor replacement/maintenance, you would set that newly changed sensor as the 2nd stringer, until it proved itself. And until the tried and true one started getting closer to pasture, regarding wear/age. Or.... just leave the left one primary, all the time! If someone does not notice the disagree (because they didn't spring for that upgrade, maybe?) you are ensuring they will be using the malfunctioning sensor on the very next flight, just in case they got lucky and it was on the secondary on this one. If you make the left one the primary, the right could fail and you could never even notice it (until you sprung for the upgrade warning light?). Even if the left/primary failed, you wouldn't switch to the other one, anyway, apparently, so you wouldn't even notice that your backup chute had a giant hole in it, for the past 3 years.
In summary, if you're not going to use the other sensor, you're not going to observe or act on the data from that sensor, then it's better, statistically, to have just 1 sensor than alternating between 2. You're just guaranteeing that if 1 of the 2 fails, you will be using that one for sure. And even if you're doing all of the above, diligently, I still see no tangible benefit from alternating which one is the primary. If there is any way to determine which of the two sensors is more likely to fail**, then alternating would have tangible cons, though.
** e.g., maybe one has worked perfectly fine for the last 1000 flights and is still in the prime of its service life, and the other one just got replaced, yesterday. I might have a slight preference, if I were to bet on one. But maybe this sensor has been through enough testing that there's an MTF graph to check, first, before I place any big money.
-
ISTR that one of the things Boeing is doing as part of fixing the Max, is to re-purpose the "dual computers" to become a true redundant system where both are active at the same time.
Anyone with software experience will tell you they probably underestimate by a factor 1000x how hard that is going to be, and the reason why the system was made the way it was, will become apparent!
-
I'm not an aviation engineer but it does leave me scratching my head as to why they'd decide to have two separate sensors but then not make some method of indicating a disagreement between the two as a standard feature. What's the point of redundancy if you're not going to detect a fault and alert the crew so they can act accordingly?
The point is that Southwest Airlines (biggest customer for the 737, it is all they fly) told Boeing that they would fine Boeing one million US Dollars per aircraft sold if their pilots needed even one minute in simulator training when moving to the Max. So, there must be NO new indictors or switches at all.
Boeing concealed the MCAS system from airlines in general, and partly from the FAA. Every procedure in the Max cockpit had to follow previous versions,
and there was a one hour tablet computer course for the differences.
It also strikes me as a very serious oversight that someone thought it was ok to make this MCAS system have so much authority that it could just keep pushing the nose down over and over beyond the ability of the flight controls to override. Surely there is some threshold where it should have been trivial for the software to determine "Ok we've pushed the nose down well beyond what we ever expect to need, something is probably wrong!"
Yes, that is pretty much the crux of the whole thing. First, Boeing told the FAA that it would only give nose-down trim for a few seconds at a time, then after some test flying the nose-high condigiton, Boeing decided they needed a lot longer nose-down trim when MCAS triggered. They decided NOT to TELL the FAA about that change! The flight computers know where the trim is, they could have easily bounded the system so it would NEVER push the stabilizer into abnormal ranges of trim. On the trim wheel, there is a green central band, with a larger range of motion to compensate when something is really wrong with the aircraft. One should never trim outside the green band unless you KNOW why you have to do this, such as improper center of gravity.
So, MCAS should have never gone out of this range, either.
The revised MCAS will apparently only command one nose-down trim movement of 9 seconds, and then NEVER do it again unless the nose too high AOA reading goes away and then occurs again.
Jon
-
*Boeing and/or FAA might not have considered the flight computer and AOA sensor (and w/e other stuff they are cleverly alternating/testing) to be as critical as a parachute. The plane may be very safe to fly without any of that, under most circumstances. But... whey carry and alternate between two "redundant" systems if you don't make them redundant?
Well, on previous 737 models, the AOA sensor was NOT a flight critical instrument. It did very little, and did NOT adjust any flight control surfaces.
BUT, on the Max, due to the much larger engines and their changed position, they needed a system to modify the flight handling characteristics at high angles of attack. So, the AOA sensors were moved up to a flight critical instrument, without anybody going back and reviewing what that really meant.
Really, if the FAA had been made aware of this very important change, I think they would have refused to certify the aircraft as it was. Most newer aircraft
with significant computer flight controls need triple-redundant computers and all instruments that feed them flight-critical data, and a complex system of voting out the bad instrument or computer. Not totally failsafe, there are cases where two instruments failed in similar manner, causing to one remaining good instrument to be voted out. But, that is getting pretty rare.
Jon
[/quote]
-
Anyone with software experience will tell you they probably underestimate by a factor 1000x how hard that is going to be, and the reason why the system was made the way it was, will become apparent!
I was thinking why this is, and I am guessing it has a lot to do with communication protocols/acknowledgements?
Make an alternate loop where the program is in standby. The standby computer will disable itself from all communications with sensors. The standby computer only receives sensor data from the active flight computer. The active flight computer will relay these updates, if and when it is not otherwise occupied with more important things. Outputs will of course be rerouted to software-only bookkeeping. When requested, by pilot input, the main computer will hand over the keys, at the earliest opportune time, perhaps with a forced time-limit for when to send the most recent update and prepare to standby, and the computers will switch roles. The new first-stringer will be working from the most recent update, while new information streams in. I'm sure it's more complicated than that. And there will have to be safeguards so that it is practically impossible for both computers to go into either standby or primary mode, together.
-
It's like you guys are starting from scratch, without having read the thread at all...
-
Forums are often a big write-only memory ;D
-
Something good is always worth doing again! ;D
-
No. Been read. Just overflowed the memory. And you gotta go thru all ^^^ this crap from the peanut gallery to read it, again. :)
Plus this one might go even better than how the expert knowitalls did it the first time. ;)
-
Plus this one might go even better than how the expert knowitalls did it the first time. ;)
Hang on, a lot of the posts were yours! :P
-
^ yeah, I remember some of it. And I'm not excluding myself from that comment. :-// >:D
If I remember correctly, this is usually where some dude comes in with "actually, you don't know what you're talking about. I fly a Cessna and I watch this guy Mentour Pilot, and...." then goes off on 99% tangent that barely touches on the current subject and simply derails it while (sometimes) correcting some minor semantics.
edit: I actually don't remember where this topic went. Regarding the alternating of the primary AOA sensor. From a hardware programmer perspective, this is of interest to me. There could be legit and observable reasons why Boeing's own engineers said things such as "MAX is designed by monkey supervised by clowns." But some folks just want to defend the industry without speculating on the specifics of the engineering fail. Perhaps if in their own culture at the FAA and Boeing, engineering could be discussed without being derailed by business politics and throwing-around-of-resumes, then the FAA could actually be useful.
There's a point where endlessly thwarted meetings and emails eventually end with people with legit still-unanswered engineering concerns to end up saying, well, fuck it. It's your funeral. And thus, the FAA becomes the dog-watching-TV.
-
I've no axe to grind. Just an observation. ;)
-
How quickly the MAX gets certified to fly again has become largely academic for the duration of the CV19 crisis, with airlines grounding large numbers of planes for lack of demand. The MAX story is now background noise in the news, if you can find it at all. More people dying of CV19 every single day than have died in MAX crashes, ever.
As for the facts, most of what's actually true in this thread is old news and not hard to find if you look. Even hitting the wiki will answer most of the questions being asked above:
https://en.wikipedia.org/wiki/Boeing_737_MAX
https://en.wikipedia.org/wiki/Maneuvering_Characteristics_Augmentation_System
-
You could argue that CV19 bought Boeing some much needed time...
-
It's a shame they continued building and filling up their car parks though - they'll have a tough time selling them now!
-
They don't have to sell them, though. The American taxpayers will be forced to buy them. Then we'll start a war. :)
-
Target selected... Engage MCAS!
Oh sorry, you mean a trade war. ;D
(Couldn't help myself)
-
No, I meant when our economy stalls, the US is gonna find a reason to drop some bombs on some people pretty soon. I.e., things will go back to the regular status quo. It's a hard job leading and driving a flawed global economy. To make this omelete, you have to sometimes break some eggs.
-
Ah yes, that's a tried and tested formula, works every time! Even for Thatcher (at least to distract the electorate).
-
Boeing and FAA didn't learn anything, still trying to fool around:
- Boeing 'inappropriately coached' pilots in 737 MAX testing: U.S. Senate report: https://www.reuters.com/article/us-boeing-737-max/boeing-inappropriately-coached-pilots-in-737-max-testing-u-s-senate-report-idUSKBN28S314 (https://www.reuters.com/article/us-boeing-737-max/boeing-inappropriately-coached-pilots-in-737-max-testing-u-s-senate-report-idUSKBN28S314)
- FAA punished whistleblowers, protected industry and covered up flaws, Senate report says: https://www.politico.com/news/2020/12/18/faa-punished-whistelblowers-boeing-senate-report-448550 (https://www.politico.com/news/2020/12/18/faa-punished-whistelblowers-boeing-senate-report-448550)
-
Regulatory bodies in other jurisdictions need to take testing more seriously too, instead of swallowing the FAA medicine raw (with or without coaching).
-
Boeing and FAA didn't learn anything, still trying to fool around:
- Boeing 'inappropriately coached' pilots in 737 MAX testing: U.S. Senate report: https://www.reuters.com/article/us-boeing-737-max/boeing-inappropriately-coached-pilots-in-737-max-testing-u-s-senate-report-idUSKBN28S314 (https://www.reuters.com/article/us-boeing-737-max/boeing-inappropriately-coached-pilots-in-737-max-testing-u-s-senate-report-idUSKBN28S314)
- FAA punished whistleblowers, protected industry and covered up flaws, Senate report says: https://www.politico.com/news/2020/12/18/faa-punished-whistelblowers-boeing-senate-report-448550 (https://www.politico.com/news/2020/12/18/faa-punished-whistelblowers-boeing-senate-report-448550)
This is enough to downgrade the FAA, which is a gov. agency that is corrupt like in those banana republic 's gov. agencies, no better like in those less developed country. ::)
Yet, Euro certification body passed and said its ok for 737 Max to fly again "in advance" of FAA, so which one is worst ? :-DD
-
Fits very well with the the philosophy of "acceptable risk" when fixing the tail issue was more expensive than paying the insurance compensation back then to slowly evolving to "killing people for profit" looks like.
-
It's a shame they continued building and filling up their car parks though - they'll have a tough time selling them now!
It's a great way of pressuring the FIA to smooth things over, or at least not make life impossible. No one wants to sink Boeing, right?
-
No one wants to sink Boeing, right?
One of the biggest player of the military–industrial complex ? Are you kidding ? >:D
-
One of the biggest player of the military–industrial complex ? Who are you try to kidding at ? >:D
They're too big to fail and don't want the MAX cancelled. Others may think the aircraft should go, so what do you do? You raise the stakes by building as many as you can. They're basically saying "What are you gonna do about it?" That should give anyone pause what Boeing's intentions and lessons learned really are.
-
One of the biggest player of the military–industrial complex ? Who are you try to kidding at ? >:D
They're too big to fail and don't want the MAX cancelled. Others may think the aircraft should go, so what do you do? You raise the stakes by building as many as you can. They're basically saying "What are you gonna do about it?" That should give anyone pause what Boeing's intentions and lessons learned really are.
The ease and profit of selling civilian product, non military planes like MAX before this fiasco, is much-much more preferable method in making money, much easier and much less stressful, rather than the prolong highly stressful environment, including constant head-ache on maintaining the bribe .. errr ... lobbying the Senate, House of Rep and top brasses at Pentagon and etc for military purchase even they're member of military industrial complex. Also compared to these bunch of big boys, "maintaining" just FAA top officials alone is a walk in the park.
-
I think the Max will be fine after this, the plane is mostly sound, it was just the idiotic design of that MCAS feature that doomed the two that went down. Other planes in that past have had teething pains, the DC-10 suffered several high profile crashes early on which it never fully recovered from, but it still went on to provide decades of reliable service once the kinks had been ironed out. I do not anticipate seeing any further 737 Max crashes related to MCAS, especially now that everyone is acutely aware of the system and what it does.
-
Have you forgotten that MCAS is the band aid for a make-it-cheap design problem?
-
Have you forgotten that MCAS is the band aid for a make-it-cheap design problem?
I thought it was just there to make the plane "feel" the same as an earlier model, to avoid recertification and retraining pilots?
-
I thought it was just there to make the plane "feel" the same as an earlier model, to avoid recertification and retraining pilots?
That's exactly what it's there for. The plane is completely flyable without it, but it has different characteristics than other 737 models so they added MCAS to automatically compensate for these differences so that a pilot trained to fly a 737 could in theory fly the Max without any additional training. Pilots are certified to fly specific aircraft types, different aircraft have different flight characteristics, that doesn't mean there's anything wrong with the plane, it just means the pilots have to be trained on the new model, or you need a system like MCAS to automatically compensate to make the new plane fly like the old plane from the pilot's perspective. There's nothing inherently wrong with this, it's not even a particularly difficult problem to solve, they just screwed up hugely, got cocky and complacent.
This has happened before, the DC-10 I mentioned had three independent hydraulic circuits, the calculated odds of all three systems failing were so low that there was no backup to these redundant hydraulic systems. Unfortunately they overlooked the fact that all three systems pass within close proximity to the #2 engine mounted in the vertical stabilizer and an uncontained engine failure could take out all three systems as happened to United flight 232.
Another classic textbook case of arrogance and complacency is the Therac-25 radiation therapy machine, calculated odds of software failing were so low that the machine lacked any sort of hardware interlocks, however they overlooked the possibility of bugs in the code and a race condition resulted in the horrific suffering, disfigurement and deaths of a handful of people by severe radiation burns before anyone realized what was going on. After fixing the software and adding hardware interlocks the Therac machines went on to provide decades of service without further injuries.
The same will be true of the 737 Max, I suspect the tragic accidents will hang over them forever and limit the popularity of the aircraft to much less than it could have otherwise been, but I have no doubt it will prove to be as reliable and safe as previous 737 variants. I would not hesitate to fly on one.
-
The new fuel efficient jet engines are larger and Boeing decided to move them in front of the wings to avoid a redesign of the landing gear which would harm the simplified certification process. That placement of the jet engines changes not just the flight characteristics, it also increases the probability of stalling. MCAS is meant to mitigate the risk of stalling. Media/press reported these details at the beginning of the investigations.
-
The new fuel efficient jet engines are larger and Boeing decided to move them in front of the wings to avoid a redesign of the landing gear which would harm the simplified certification process. That placement of the jet engines changes not just the flight characteristics, it also increases the probability of stalling. MCAS is meant to mitigate the risk of stalling. Media/press reported these details at the beginning of the investigations.
No, sorry, that's not correct. ALL jets that have the engines slung under the wings will tend to pitch up when throttle is increased, that is an inherent characteristic of this design. The Max moved the engines and has larger engines so it exhibits this characteristic to a greater degree. Excessive pitch up at low airspeed can induce a stall, but if the pilot is aware of how the aircraft handles then they know how to avoid doing this. The Max does not need MCAS to fly, it needs MCAS to have the same amount of pitch-up tendency under throttle as the earlier 737 models so that the different flight characteristics are transparent to the crew. ALL aircraft have unique characteristics that will get a person into trouble if they don't know what they're doing, that is precisely why pilots of large aircraft have to be certified to fly that specific model of aircraft. Boeing could have decided to skip MCAS entirely, then released exactly the same plane without it and it would have been perfectly fine aircraft, except crews certified to fly the earlier 737 models would require additional training to fly the new model and customers wished to avoid this.
This is one area where Airbus has an advantage because their planes are already entirely fly by wire so there is no need for a separate system, the human pilot already has no direct control over the control surfaces, the software is tuned to provide the desired handling characteristics.
-
This is one area where Airbus has an advantage because their planes are already entirely fly by wire so there is no need for a separate system, the human pilot already has no direct control over the control surfaces, the software is tuned to provide the desired handling characteristics.
With all sorts of fallback modes (automatic or commanded) that have to be learned for each major Airbus type (they have different type ratings, not one for all). It's very different from Boeings approach. Whether it's better is the subject of many discussions. Also, it's not quite right. Airbus does have final fallback mechanical mode on engines, trim tabs, and rudder, intended to give enough control to keep the aircraft level during a complete computer failure and reset. If they don't get at least one computer back fairly quickly, it's very serious.
-
The Max does not need MCAS to fly, it needs MCAS to have the same amount of pitch-up tendency under throttle as the earlier 737 models so that the different flight characteristics are transparent to the crew.
From https://en.wikipedia.org/wiki/Maneuvering_Characteristics_Augmentation_System:
The Maneuvering Characteristics Augmentation System (MCAS) flight control law was implemented on the 737 MAX to mitigate the aircraft's tendency to pitch up because of the aerodynamic effect of its larger, heavier, and more powerful CFM LEAP-1B engines and nacelles. The stated goal of MCAS, according to Boeing, was to provide consistent aircraft handling characteristics at elevated angles of attack in certain unusual flight conditions only and hence make the 737 MAX perform similarly to its immediate predecessor, the 737NG.
-
...
The same will be true of the 737 Max, I suspect the tragic accidents will hang over them forever and limit the popularity of the aircraft to much less than it could have otherwise been, but I have no doubt it will prove to be as reliable and safe as previous 737 variants. ...
The 737MAX could have been made to be as reliable and safe as previous 737 variants, right from the start; it is really unfortunate that Boeing chosen to fool the FAA, the airlines, the pilots and the flying customers.
:)
-
The Max does not need MCAS to fly, it needs MCAS to have the same amount of pitch-up tendency under throttle as the earlier 737 models so that the different flight characteristics are transparent to the crew.
An unfortunate choice of words. The one thing that ill conceived a implemented MCAS, and indeed the whole sordid matter of Boeing's behaviour during the investigation and recertification exercise hasn't been is "transparent". ::)
-
One of the biggest player of the military–industrial complex ? Who are you try to kidding at ? >:D
They're too big to fail and don't want the MAX cancelled. Others may think the aircraft should go, so what do you do? You raise the stakes by building as many as you can. They're basically saying "What are you gonna do about it?" That should give anyone pause what Boeing's intentions and lessons learned really are.
There's really not that big a problem. If the previous version of the 737 is OK, then the Max is OK, as long as EVERY pilot knows how MCAS works, what will set it off improperly (damaged AOA sensor) and how to recover (trim nose up, then hit the switches to disable automatic and electric trim).
And, DON'T disable electric trim with the aircraft badly trimmed, use your electric trim to override MCAS until the aircraft is properly trimmed BEFORE disabling the electric trim.
The real problem is that MCAS was NOT known to most pilots, and it behaved differently from a simple runaway trim that all pilots are trained for.
Thus, they didn't recognize this a a form of a trim runaway, and failed to react to stop it.
Jon
-
An unfortunate choice of words. The one thing that ill conceived a implemented MCAS, and indeed the whole sordid matter of Boeing's behaviour during the investigation and recertification exercise hasn't been is "transparent". ::)
Yes, it is pretty hard to understand how NOBODY ever asked "what happens if the AOA sensor fails, and nobody responds to that?"
It is going to kick in MCAS right after takeoff, a high workload time, and doesn't give much of an indication in the cockpit of the 737.
Without strong emphass on training for this condition, the flight crew would be taken totally by surprise. And, assuming they WERE
trained, would they remember that years later when the condition actually appeared? This whole scenario where they told almost NOBODY that this
system even EXISTED is totally amazing.
And, of course, Soutwest Airlines is quite complicit in this by fining Boeing $1 million per aircraft if there is any sim time required to learn the Max.
Boeing should have pushed back on that one.
Jon
-
... And, assuming they WERE trained, would they remember that years later when the condition actually appeared?
Assuming they were trained, that would have been covered during the recurring training, every six months.
And, of course, Soutwest Airlines is quite complicit in this by fining Boeing $1 million per aircraft if there is any sim time required to learn the Max.
Boeing should have pushed back on that one.
Boeing sales pitch to Southwest Airlines most probably covered the "saving" in training cost. Now, after this fiasco created by Boeing, Southwest Airlines is not "saving" as much, in training.
Boeing lied to everybody, Boeing will probably pay these penalties to Southwest Airlines.
I have a friend who became type rated on the 737MAX, two years ago, and he confirmed to me that all the technicalities surrounding the MCAS were kept secret, from the airlines, by Boeing.
:)
-
There's really not that big a problem. If the previous version of the 737 is OK, then the Max is OK, as long as EVERY pilot knows how MCAS works, what will set it off improperly (damaged AOA sensor) and how to recover (trim nose up, then hit the switches to disable automatic and electric trim).
And, DON'T disable electric trim with the aircraft badly trimmed, use your electric trim to override MCAS until the aircraft is properly trimmed BEFORE disabling the electric trim.
The real problem is that MCAS was NOT known to most pilots, and it behaved differently from a simple runaway trim that all pilots are trained for.
Thus, they didn't recognize this a a form of a trim runaway, and failed to react to stop it.
Jon
The whole point of MCAS was to keep the 737 the same as previous models. Requiring any retraining would be a big deal when the competitor does not have such a requirement and that's what Boeing tried to prevent, even at the cost of human lives. That in itself should tell us it's a considerable issue.
-
There's really not that big a problem. If the previous version of the 737 is OK, then the Max is OK, as long as EVERY pilot knows how MCAS works, what will set it off improperly (damaged AOA sensor) and how to recover (trim nose up, then hit the switches to disable automatic and electric trim).
And, DON'T disable electric trim with the aircraft badly trimmed, use your electric trim to override MCAS until the aircraft is properly trimmed BEFORE disabling the electric trim.
The real problem is that MCAS was NOT known to most pilots, and it behaved differently from a simple runaway trim that all pilots are trained for.
Thus, they didn't recognize this a a form of a trim runaway, and failed to react to stop it.
Jon
The whole point of MCAS was to keep the 737 the same as previous models. Requiring any retraining would be a big deal when the competitor does not have such a requirement and that's what Boeing tried to prevent, even at the cost of human lives. That in itself should tell us it's a considerable issue.
also if NG and MAX wheren't considered "the same" an airline that has a mix of NG and MAX can't move pilots around without the added cost and time to keep a dual type rating
-
Boeing 737 Max project is criminal conduct in a hundred ways, I don't expect this to go smoothly despite the politics.
We all know what happens when you roll out an ugly baby- a product with safety issues that are covered up to sneak through regulatory. When the problems come up (containment problem) you can't go backwards to make design changes. Hardware is like that. The "software fix" executives push for, very limited and can't cover much for deficient hardware.
Dennis Muillenburg is enjoying his $62M stock, pension , last paycheque and avoiding jail. There's no consequences.
“Boeing executives should be walking away in handcuffs, not with millions of dollars,” Zipporah Kuria, who lost her father, Joseph Waithaka, in Ethiopian Airlines flight 302, said in a statement.
Strange Volkswagen, Audi and Takata have a CEO and few token managers in criminal trial proceedings over their fiascos.
Not a peep about the AoA sensor's poor reliability, if that has been addressed. It was the problem in the first place.
The planes have been in storage an awful long time which adds new dangers.
Recent Dec. 22, 2020 Air Canada 737 Max taken out of storage, had problems "left engine low hydraulic pressure indication" (http://avherald.com/h?article=4e0ef146) then "indication of fuel imbalance", so they shut off that engine and PAN PAN landed :palm:
-
There's really not that big a problem. If the previous version of the 737 is OK, then the Max is OK, as long as EVERY pilot knows how MCAS works, what will set it off improperly (damaged AOA sensor) and how to recover (trim nose up, then hit the switches to disable automatic and electric trim).
And, DON'T disable electric trim with the aircraft badly trimmed, use your electric trim to override MCAS until the aircraft is properly trimmed BEFORE disabling the electric trim.
The real problem is that MCAS was NOT known to most pilots, and it behaved differently from a simple runaway trim that all pilots are trained for.
Thus, they didn't recognize this a a form of a trim runaway, and failed to react to stop it.
Jon
The whole thing was the perfect shitstorm of poor design decisions, poor software QA, politics, arrogance, complacency and carelessness that all came together and blew up. It almost any one of these things had been done differently the whole catastrophe could have been avoided. It would have been trivial to limit the authority of MCAS so that it could not wind the trim down beyond the range that could be overridden by the pilot's control input, that was an absolutely massive oversight that even a novice QA engineer should have caught. The ball was dropped at so many levels that a disaster was virtually guaranteed. If a system is intended to be fully automated to the degree that the crew is not even aware that it exists then it damn well better be rock solid with redundant everything and extensive testing. Even if no additional training is required to operate the aircraft, the crew should still be aware of the existence of the system that makes this possible.
-
Part of the problem solved ... a good sign for Boeing ... :-DD
-> U.S. fliers less familiar with Boeing 737 MAX crashes two years on, but wary when reminded (https://www.reuters.com/article/us-boeing-737max-travel-poll/u-s-fliers-less-familiar-with-boeing-737-max-crashes-two-years-on-but-wary-when-reminded-reuters-ipsos-poll-idUSKBN2920TU)
-
Part of the problem solved ... a good sign for Boeing ... :-DD
-> U.S. fliers less familiar with Boeing 737 MAX crashes two years on, but wary when reminded (https://www.reuters.com/article/us-boeing-737max-travel-poll/u-s-fliers-less-familiar-with-boeing-737-max-crashes-two-years-on-but-wary-when-reminded-reuters-ipsos-poll-idUSKBN2920TU)
That's not too surprising. The same happened with the DC-10, and that involved multiple incidents with several different iterations of "fixing" the cargo door and other problems. Eventually people were flying on them and the related MD-11 for many years. The MD-80 too, I flew on one about a year after the jackscrew failed causing that Alaska Airlines flight to crash, a guy who's office was a few doors down from mine and his wife both died on that. It crossed my mind when I sat down in the plane but it didn't stop me from flying on it. I've always been fascinated by airplanes and pay attention to exactly what kind of aircraft I'm on and occasionally I've chosen flights specifically to ride on a particular type of plane, but I suspect most people are probably only vaguely aware if they know at all.
-
Not a peep about the AoA sensor's poor reliability, if that has been addressed. It was the problem in the first place.
That's almost beside the point. AoA sensors are going to fail. Whether 1/1,000 hours or 1/1,000,000 hours, there are (or Boeing would hope there will be) enough of these birds in the air that failure is inevitable and must be handled gracefully. Obviously a high failure rate would be a concern, but it's hardly the biggest problem here, and warrants a far less aggressive regulatory response than not reacting to AoA failure appropriately does.
According to the report on the Lion Air flight, they are speculating that the AoA failure was not due to hardware failure per se, but a nonstandard (however, approved) calibration procedure in use at the re-manufacturer, and speculate that the operator had the test equipment in 'REL' mode, introducing a bias into the AoA signal. I'm not sure the Ethiopian investigation has speculated on what caused that failure.
I've been following this whole debacle closely since the first accidents, and it just keeps getting more and more :palm: on the Boeing side. It's really pretty egregious the level of engineering and particularly management failure that happened here. From negotiating a 'no training' deal with airlines before they even understood what training would/might be required, to actively discouraging customers from giving their pilots training, to covering up the existence of the system, to the software QA issues, to the 'oversight' of this deadly failure mode in their failure analysis, ignored QA problems in manufacturing, etc. etc. etc. it's just... malicious failure all the way down.
IMO the Final Order does enough to prevent future incidences like this one, I think the MAX will be safe from MCAS at least, once they get the return from storage issues ironed out. But all of this really doesn't make me want to get on a Boeing aircraft, both because who knows what other danger is lurking behind this management, and who wants their money going to such a company?
-
The AoA sensor is another shitstorm, hardware failure plus its undocumented relative calibration problem:
"...the output from Resolver 2 was correct when the internal heaters were operating but stopped working again when the temperature dropped.
The investigation discovered that a loose loop of the very fine magnet wire from the primary rotor coil was trapped in the epoxy which was meant to hold the end cap insulator in place. The trapped magnet wire thus adhered to both the end cap insulator and the rotor shaft insulator which had very different coefficients of thermal expansion (CTE). As the wire expanded and contracted to the two different environments, the wire became fatigued and showed multiple ridges and cracks before breaking. The wire failure created an intermittent open circuit, dependent on temperature. The sensor worked fine at temperatures above 60°C (140°F) but failed at temperatures below that."
https://fearoflanding.com/accidents/accident-reports/lion-air-610-the-faulty-aoa-sensor/ (https://fearoflanding.com/accidents/accident-reports/lion-air-610-the-faulty-aoa-sensor/)
-
The AoA sensor is another shitstorm, hardware failure plus its undocumented relative calibration problem:
"...the output from Resolver 2 was correct when the internal heaters were operating but stopped working again when the temperature dropped.
The investigation discovered that a loose loop of the very fine magnet wire from the primary rotor coil was trapped in the epoxy which was meant to hold the end cap insulator in place. The trapped magnet wire thus adhered to both the end cap insulator and the rotor shaft insulator which had very different coefficients of thermal expansion (CTE). As the wire expanded and contracted to the two different environments, the wire became fatigued and showed multiple ridges and cracks before breaking. The wire failure created an intermittent open circuit, dependent on temperature. The sensor worked fine at temperatures above 60°C (140°F) but failed at temperatures below that."
https://fearoflanding.com/accidents/accident-reports/lion-air-610-the-faulty-aoa-sensor/ (https://fearoflanding.com/accidents/accident-reports/lion-air-610-the-faulty-aoa-sensor/)
I'm not sure what you mean by undocumented relative calibration problem. This was a problem, but it was a documented and allowed procedure that was used. The calibration issue was due to the remanufacturer using a nonstandard piece of test equipment and associated nonstandard procedure, with the approval of the FAA, which included this mode that was not part of the recommended test equipment. This procedure was documented and approved, it just failed to correctly deal with the setting of this REL switch. As this wasn't a recommended procedure, I don't think you can blame Boeing or the AOA vane subcontractor for that.
Yeah, the initial failure that triggered replacement with the miscalibrated sensor is certainly interesting, but it definitely doesn't strike me as a shitstorm. Possibly a QA issue, possibly just an unexpected consequence of the manufacturing process, should be easy to fix going forward and isn't obviously a result of malice. It's not made or designed by Boeing, and I haven't seen anything implicating the sort of management problems at Boeing at their subcontractors (yes, Collins failed to catch the AOA DISAGREE alert issue, as did Boeing, but they were then ordered not to fix the problem because ?????). These kind of manufacturing issues always come up with new aircraft in one system or another, get resolved, and because the designs are usually proper, don't result in crashes. Aircraft are incredibly complicated, and to expect no issues at all of this type isn't reasonable, which is why the engineering needs to account for occasional failures.
Indeed, what actually happened in this case - the problem was detected by the flight computers, the plane flew several legs safely (probably should have been grounded earlier, yet...), eventually the problem was isolated, and the part replaced - is what one would expect to happen. In fact, if I understand the fault correctly, I don't think it would be likely for this original failure to trigger MCAS at all, an open circuit is an outright failure that would be detected, and the sensor was otherwise providing correct readings. Ultimately (bar MCAS), the AOA vane is a non-critical and 'fault tolerant' system on the 737 - I can't easily find if the 737NG and 737MAX use the same AOA sensor part; I would guess that they do or one of very similar design, and NG has been flying in the 1000s without AOA vanes contributing to an accident for 20 years.
Even if you're right and this is a complete disaster of an AOA sensor design or manufacture for some reason, failure still shouldn't have had any effect on safety of flight, even complete loss of AOA data isn't an issue for any 737 (which is why it's only doubly redundant), so I think this is just an interesting footnote to the story. If the design of the system on the Boeing side wasn't such a clusterfuck, the inconsistent readings would be detected, trigger a disagree, and the faulty data wouldn't be used for anything.
-
It must be so easy (OK, it may sting a bit) to pay up to make it go away and [EDIT for Nusa's benefit: nobody] going to Jail.
Boeing has agreed to pay $2.5bn (£1.8bn) to settle US criminal charges that it hid information from safety officials about the design of its 737 Max planes.
https://www.bbc.co.uk/news/business-55582496 (https://www.bbc.co.uk/news/business-55582496)
-
It must be so easy (OK, it may sting a bit) to pay up to make it go away and not going to Jail.
Boeing has agreed to pay $2.5bn (£1.8bn) to settle US criminal charges that it hid information from safety officials about the design of its 737 Max planes.
https://www.bbc.co.uk/news/business-55582496 (https://www.bbc.co.uk/news/business-55582496)
Out of curiosity, exactly how would you put Boeing in jail, even if you wanted to?
-
...
https://www.bbc.co.uk/news/business-55582496 (https://www.bbc.co.uk/news/business-55582496)
Out of curiosity, exactly how would you put Boeing in jail, even if you wanted to?
The jail sentence would probably be for the high ranking management personnel and the Boeing employees (engineers?) who were acting as FAA representative. They definitively deserve criminal charge and jail time.
:)
-
...
https://www.bbc.co.uk/news/business-55582496 (https://www.bbc.co.uk/news/business-55582496)
Out of curiosity, exactly how would you put Boeing in jail, even if you wanted to?
The jail sentence would probably be for the high ranking management personnel and the Boeing employees (engineers?) who were acting as FAA representative. They definitively deserve criminal charge and jail time.
:)
Except you cant get billions out of individual employees, nor can you jail them without expensive trials with high burdens of proof. Even gross incompetence is arguably only a firing offence, not a crime. Enough for reasonable doubt in most cases, anyway.
Anyway, the point is even though there's a legal fiction that companies are "people", jail is a meaningless threat to such a "person".
-
Boeing is made of teflon, and actually can't be convicted of anything criminal :palm:
"...Critically, this avoids a potential criminal conviction of Boeing as a company. That’s important for Boeing as a key U.S. defense contractor; a conviction could have excluded it from future government contracts."
“The settlement sidesteps any real accountability in terms of criminal charges,” DeFazio said {U.S. House Transportation Committee Chair Peter DeFazio, D-Ore.} “From where I sit this attempt to change corporate behavior is pathetic … Senior management and the Boeing board were not held to account, and in fact, the former CEO skated out with more than $60 million."
https://www.seattletimes.com/business/boeing-aerospace/boeing-agrees-to-pay-2-5b-to-settle-criminal-fraud-charges-over-737-max/ (https://www.seattletimes.com/business/boeing-aerospace/boeing-agrees-to-pay-2-5b-to-settle-criminal-fraud-charges-over-737-max/)
-
The only way to gain trust, is to punished those who did the corruption either Boeing and FAA personnels with heavy punishment like long time jail.
I guess in China, these people will face death penalty. especially the fiasco involves own citizen's life.
-
It's disappointing, but to be expected. Boeing is systemically relevant for the US.
-
Another thig is that Boeing knew that these sensors were critical to operation, and made the flight computers capable of recognising and handling the failure of one of the sensors, but then made this programming an expensive "add on" price option, with no explanation as to what the system does, as far as the information buying clients were given.
Looks like sales gave some pie in the sky promises, as in make it exactly the same, irrespective that the plane is now twice the weight, twice the length and twice the capacity, but just can use the same gate design, as changing it would mean training pilots again how to park, and need a new gate ramp to allow the height difference. So the gate design, fixed in the early 1970's was the criteria, and keeping the cockpit the same, but shoving more in there, thus the manual controls were downsized to the point you would need a weightlifter to turn them at all, with the control surfaces unloaded. No extra training, as the simulators did not have any scenario where MCAS was failed built in them, as it would be "new training" again, not desired.
-
Well, that's a good thing that Boeing got charged for this fiasco.
But where will those 2.5 billion dollars come from? Who is really going to pay in the end?
Oh and, the new CEO put a major blame on his predecessor - which was deserved - but he better not get Boeing into a similar situation again. Talk is cheap.
And what is the former CEO going to face really?
-
And what is the former CEO going to face really?
Face ? How about "facing" the sky, sun bathing in private beach in covid era while sipping bozz, accompanied by rainbow in the sky and lives happily ever after ? :-DD
-> Crash victims' families 'sickened' by fired Boeing CEO's $90m payout (https://www.smh.com.au/business/companies/crash-victims-families-sickened-by-fired-boeing-ceo-s-90m-payout-20200114-p53r7m.html)
... and imagine one of your loved one, like parent, spouse or children is one of the victim.
-
Indeed, what actually happened in this case - the problem was detected by the flight computers, the plane flew several legs safely (probably should have been grounded earlier, yet...), eventually the problem was isolated, and the part replaced - is what one would expect to happen. In fact, if I understand the fault correctly, I don't think it would be likely for this original failure to trigger MCAS at all, an open circuit is an outright failure that would be detected, and the sensor was otherwise providing correct readings. Ultimately (bar MCAS), the AOA vane is a non-critical and 'fault tolerant' system on the 737 - I can't easily find if the 737NG and 737MAX use the same AOA sensor part; I would guess that they do or one of very similar design, and NG has been flying in the 1000s without AOA vanes contributing to an accident for 20 years.
Well, the difference is that in all 737's up through the NG, the AOA sensor is for information ONLY, it does not control ANY flight control surface.
It may be used to provide a correction factor to the air data computer. On the 737MAX, however, through MCAS, it DOES control the trimmable horizontal stabilizer, which moves it into a totally DIFFERENT class of sensor. In this case, much greater attention to failure modes SHOULD have been given.
Even if you're right and this is a complete disaster of an AOA sensor design or manufacture for some reason, failure still shouldn't have had any effect on safety of flight, even complete loss of AOA data isn't an issue for any 737 (which is why it's only doubly redundant), so I think this is just an interesting footnote to the story. If the design of the system on the Boeing side wasn't such a clusterfuck, the inconsistent readings would be detected, trigger a disagree, and the faulty data wouldn't be used for anything.
The AOA sensors on the MAX are NOT redundant! Only one is used at a time, although through the ARINC bus both flight computers can read both sensors. That's why there was an ($80K) optional AOA disagree light that could be purchased. Most airlines did NOT purchase this option, as then you had to TRAIN for what the light meant. So, the MAX has two flight computers. Only one is actively controlling flight control surfaces at any time. The active computer is switched every takeoff. The output of each computer drives the instruments on one side (captain / first officer), using the sensors (AOA, air data computer, etc.) on that side. So, while there is a "standby" redudant system of sensors, instruments and computers, it is NOT a dual redundant system. Most of the larger and newer commercial aircraft use triple-redundant systems with voting logic, so that any component that fails can be cut out of the control loops. Even the flight surface actuators have three separate actuators in series, so that any failure can simply be overridden by the other two.
But, not the 737.
As for the "several legs safely" comment, not quite true. (I'm getting the two 737 crashes confused, now.) So, first, every other flight, if the plane is left powered up, it switches which computer and sensors are being used. (If powered off, then it starts with computer #1 again.)
So, half the flights would APPEAR fine, but they had no backup computer/sensor set to fall back on. Then, at least one of the flights had the stick shaker and alarms going off for the ENTIRE flight! This, of course, is totally amazing, imagine the management pressure causing a pilot to complete an entire flight leg with this level of malfunction of the aircraft! That is clear mis-management, of course!
Jon
-
...
So, half the flights would APPEAR fine, but they had no backup computer/sensor set to fall back on. Then, at least one of the flights had the stick shaker and alarms going off for the ENTIRE flight! This, of course, is totally amazing, imagine the management pressure causing a pilot to complete an entire flight leg with this level of malfunction of the aircraft! That is clear mis-management, of course!
I suggest watching the movie "Whisky Romeo Zulu" to see how mis-management goes in some countries.
At this particular airline, among other things, the pilots were "trained" to ignore Fire Alarms.
Unfortunately, it ended up in a big fireball. There were operating 737, the Classic ones.
:)
-
Would you like to share a link to watch it somewhere with EN subtitles?
-
Would you like to share a link to watch it somewhere with EN subtitles?
I have it on DVD. It is in Spanish with English subtitles. I buy my movies on discs. Maybe it is available somewhere for download or streaming.
It seems to be available on Netflix (in some countries), but I do not use Netflix.
:)
-
Well, the difference is that in all 737's up through the NG, the AOA sensor is for information ONLY, it does not control ANY flight control surface.
It may be used to provide a correction factor to the air data computer. On the 737MAX, however, through MCAS, it DOES control the trimmable horizontal stabilizer, which moves it into a totally DIFFERENT class of sensor. In this case, much greater attention to failure modes SHOULD have been given.
It also controls the stick shaker/stall horn, and several other computed indications like the 'eyebrows', but yes it doesn't touch any flight controls. The addition of such functionality without properly considering the risks of bad AoA data was the problem, not the AoA sensor itself. I think we are in agreement here, I just don't see the AoA sensor component failure itself as anything significant in this story, but you seem to be pushing it as a major part of the issue. The fundamental problem was the failure of the aircraft to appropriately react to that failure.
The AOA sensors on the MAX are NOT redundant! Only one is used at a time, although through the ARINC bus both flight computers can read both sensors.
Yeah, I misspoke here, redundant is incorrect terminology, since it can't recover from failure, only (potentially) detect it. They are (intended to be) fault tolerant, in that bad sensors will be detected, indicated, and data discarded, regardless of the fact that the ADIRU only uses one source of data at any one time. In any case, the point was that the AoA data isn't necessary for safe flight, so they could 'get away with' this methodology - as long as they correctly discard bad data - not that their detection of bad data was sufficient. MCAS is also not required for safe flight, and depends on the AOA data. As much as I think MCAS is a gigantic kludge and this sort of thing should never be acceptable in the design of an aircraft, the logic does make sense.
That's why there was an ($80K) optional AOA disagree light that could be purchased. Most airlines did NOT purchase this option, as then you had to TRAIN for what the light meant. So, the MAX has two flight computers. Only one is actively controlling flight control surfaces at any time. The active computer is switched every takeoff. The output of each computer drives the instruments on one side (captain / first officer), using the sensors (AOA, air data computer, etc.) on that side. So, while there is a "standby" redudant system of sensors, instruments and computers, it is NOT a dual redundant system. Most of the larger and newer commercial aircraft use triple-redundant systems with voting logic, so that any component that fails can be cut out of the control loops. Even the flight surface actuators have three separate actuators in series, so that any failure can simply be overridden by the other two.
but then made this programming an expensive "add on" price option, with no explanation as to what the system does, as far as the information buying clients were given.
AOA DISAGREE was not an optional feature. An AOA (value) indicator was the expensive option. The problem here is that AOA DISAGREE was broken for years due to a software bug/misunderstanding that Boeing instructed Collins not to fix once it was discovered, and neglected to inform its customers or pilots about. The 737MAX was certificated with this indicator available, so for regulatory compliance, it MUST be present, but wasn't due to the unfixed bug.
But, not the 737.
This is because these modern aircraft are fly-by-wire and depend on AoA data for safety of flight. I absolutely agree that 737MAX should never have been certificated without a modern FBW system and cohesive envelope protection. But, again, that has nothing to do with the AoA sensor itself.
As for the "several legs safely" comment, not quite true. (I'm getting the two 737 crashes confused, now.) So, first, every other flight, if the plane is left powered up, it switches which computer and sensors are being used. (If powered off, then it starts with computer #1 again.)
So, half the flights would APPEAR fine, but they had no backup computer/sensor set to fall back on. Then, at least one of the flights had the stick shaker and alarms going off for the ENTIRE flight! This, of course, is totally amazing, imagine the management pressure causing a pilot to complete an entire flight leg with this level of malfunction of the aircraft! That is clear mis-management, of course!
What I'm talking about is that the Lion Air aircraft flew several legs with a faulty AoA sensor. This was detected, logged by the crews, and looked into by maintenance. None of these flights had any safety issue because the failure was a hard one - the resolver failed open as temperature fell, the flight computers detected this and knew the data was bad, so it didn't lead to any safety (or otherwise) issues. Eventually maintenance got around to replacing the sensor with the accident one that had a calibration bias. It was after this replacement that the flight you're mentioning occurred, where the crew experienced the same conditions as the accident flight, and just managed to deal with it better. This just shows that AoA *failure* is not a problem for this aircraft, the problem was that the sensor appeared to be functional as far as the flight computers could tell, but was producing biased indications, which wasn't something the Boeing design handled properly.
Don't get me wrong here. The level of incompetence, malfeasance on Boeing's part, and the extent of regulatory capture of the FAA is staggering, and the people who were documented to have mislead customers and pushed to cover this up absolutely deserve jail time. I just don't want people to think that AoA sensors failing is something we should really care about - because it is going to happen and the systems must be designed to tolerate any sort of failure, including a bias like this.
-
Don't forget the old adage from Segal's law (https://en.wikipedia.org/wiki/Segal%27s_law)- "with two clocks one can never know the correct time". The probability proof shows redundant watches (sensors) are useless.
You need a majority vote, one reason Airbus uses three pitot tubes and even then, having identical physical configuration means they like to fail the same way, bad heater design and ice included.
AF447 (https://en.wikipedia.org/wiki/Air_France_Flight_447) crash shows automation is lost without accurate sensor input. Try writing S/W that deals with sensor failures, it is a lot of math and at some point the machine needs the pilot to decide what action to take.
-
Don't forget the old adage from Segal's law (https://en.wikipedia.org/wiki/Segal%27s_law)- "with two clocks one can never know the correct time". The probability proof shows redundant watches (sensors) are useless.
You need a majority vote, one reason Airbus uses three pitot tubes and even then, having identical physical configuration means they like to fail the same way, bad heater design and ice included.
AF447 (https://en.wikipedia.org/wiki/Air_France_Flight_447) crash shows automation is lost without accurate sensor input. Try writing S/W that deals with sensor failures, it is a lot of math and at some point the machine needs the pilot to decide what action to take.
You need a majority vote if you need valid data for safe flight, as in an FBW aircraft, and especially for IAS which is quite critical both for manual and automatic flight in a normal regime. The concept of 737MAX design was (and still is) that AoA data (and by extension, MCAS) is not essential to the safety of flight, which I think is a fair assessment. Losing it changes effectively nothing except during approach to stall, which a transport aircraft should never encounter. If you accept that premise, two sensors is sufficient to detect a disagree and disable any (automated, at least) uses of the data. This is the basis under which the aircraft will be returned to service.
AF447 is almost the opposite case as 737MAX - the aircraft detected the problem, and degraded the automation as necessary to make safe recovery possible - this is exactly what should have happened with MAX (minus the inappropriate pilot response and ensuing crash, of course - but in the MAX case this wouldn't have changed the flight characteristics or indications in any meaningful way).
-
Yes and no! ;) The 737MAX can be operated without MCAS. But if you tell pilots that the 737MAX behaves the same like the 737NG MCAS becomes a critical system. WIthout MCAS the pilots would experience a non expected behavior in specific critical situations.
-
Yes and no! ;) The 737MAX can be operated without MCAS. But if you tell pilots that the 737MAX behaves the same like the 737NG MCAS becomes a critical system. WIthout MCAS the pilots would experience a non expected behavior in specific critical situations.
but I'd think in a critical situation a plane behaving different is much preferred to a plane that behaves unpredictable
-
Don't forget the old adage from Segal's law (https://en.wikipedia.org/wiki/Segal%27s_law)- "with two clocks one can never know the correct time". The probability proof shows redundant watches (sensors) are useless.
You need a majority vote, one reason Airbus uses three pitot tubes and even then, having identical physical configuration means they like to fail the same way, bad heater design and ice included.
AF447 (https://en.wikipedia.org/wiki/Air_France_Flight_447) crash shows automation is lost without accurate sensor input. Try writing S/W that deals with sensor failures, it is a lot of math and at some point the machine needs the pilot to decide what action to take.
yep, there have been cases where the one functional sensor was ignored because the two other sensors failed with the same wrong value
-
another one down (09 Jan 2021)
Boeing 737-524
https://www.nytimes.com/2021/01/09/world/asia/indonesia-plane.html (https://www.nytimes.com/2021/01/09/world/asia/indonesia-plane.html)
"another one" is misleading, since this thread is about the MAX.
The 737-500's were produced from 1990-1999. This particular one is a 27-year-old former United Airlines plane (no major operators still use them in the US). Way too early to say what went wrong.
https://aviation-safety.net/database/record.php?id=20210109-0 (https://aviation-safety.net/database/record.php?id=20210109-0)
https://avherald.com/h?article=4e18553c (https://avherald.com/h?article=4e18553c)
-
I think we are in agreement here, I just don't see the AoA sensor component failure itself as anything significant in this story, but you seem to be pushing it as a major part of the issue.
I think that may have been some other commenter. As a delicate vane sticking out the side of the aircraft, the AOA vane is quite susceptibel to damage, they get broken all the time during ground handling and jetway movement. And, the aircraft systems should be able to deal with crazy readings. If the vane is banged, it can easily give a jammed or just incorrect reading.
AOA DISAGREE was not an optional feature. An AOA (value) indicator was the expensive option. The problem here is that AOA DISAGREE was broken for years due to a software bug/misunderstanding that Boeing instructed Collins not to fix once it was discovered, and neglected to inform its customers or pilots about. The 737MAX was certificated with this indicator available, so for regulatory compliance, it MUST be present, but wasn't due to the unfixed bug.
Thanks for this clarification, I think my incorrect understanding of this has been coming from multiple sources, so I'm not the only one who got it wrong.
OK, so what, exactly, is the Collins bug on AOA disagree? Does it NEVER light up? Or, only in certain cases, but not this one?
This is because these modern aircraft are fly-by-wire and depend on AoA data for safety of flight. I absolutely agree that 737MAX should never have been certificated without a modern FBW system and cohesive envelope protection.
Well, I partially agree. It would have been a BETTER, and safer, plane with a triple-redundant fly by wire control system, 3 AOA sensors, etc. But that would have increased costs quite a bit. If the existing flight control system had a working AOA disagree and MCAS would not allow the stabilizer trim to automatically go into extreme positions, I don't really see a problem with the 737MAX. Sure, it IS old-school, but there are a TON of them flying pretty safely all over the world (since they got that nasty rudder actualtor issue solved about 30 years ago.)
Jon
-
I think that may have been some other commenter. As a delicate vane sticking out the side of the aircraft, the AOA vane is quite susceptibel to damage, they get broken all the time during ground handling and jetway movement. And, the aircraft systems should be able to deal with crazy readings. If the vane is banged, it can easily give a jammed or just incorrect reading.
Apologies then!
Thanks for this clarification, I think my incorrect understanding of this has been coming from multiple sources, so I'm not the only one who got it wrong.
OK, so what, exactly, is the Collins bug on AOA disagree? Does it NEVER light up? Or, only in certain cases, but not this one?
Basically it incorrectly got tied to the paid AOA indicator, which is where the confusion comes from, I think. This wasn't what the design intended, but due to a misunderstanding/miscommunication between Boeing and Collins on a related trouble report, it is what ended up being implemented. Collins actually found this bug some years ago, and informed Boeing, but it was requested that Collins hold off on a fix until a future anticipated firmware update or some such weak reasoning, and Boeing never informed its customers. This is documented in the Congressional report, I haven't really seen it discussed much elsewhere.
Well, I partially agree. It would have been a BETTER, and safer, plane with a triple-redundant fly by wire control system, 3 AOA sensors, etc. But that would have increased costs quite a bit. If the existing flight control system had a working AOA disagree and MCAS would not allow the stabilizer trim to automatically go into extreme positions, I don't really see a problem with the 737MAX. Sure, it IS old-school, but there are a TON of them flying pretty safely all over the world (since they got that nasty rudder actualtor issue solved about 30 years ago.)
Fair enough, I think 737MAX will be safe once the required changes are done, notwithstanding some other failures due to Boeing's just massive bungling of this project.
However, I strongly believe that this concept of 'update the 50 year old airframe on the same type certificate under relaxed rules and with minimal pilot training' is fundamentally flawed. It seems to create perverse incentives, discouraging safety improvements while simultaneously encouraging nasty (and fundamentally useless, other than to satisfy the similarity requirement) hacks like MCAS that are far more likely to lead to design flaws, as they aren't considered as part of a cohesive design process, but as a tacked on standalone project. As the industry matures and these old designs get older and older, we need to do something to push the industry forward without bandaid fix on top of bandaid fix. The 737NG already has some...weird...design choices due to this, and MAX just takes it too far. What next? Wasn't such a big deal 30 years ago, but now this design is over 50 years old and a lot has been learned since that should be integrated into every new plane coming off an assembly line. There was a lot else going on at Boeing that was problematic, but this is where I think the regulators really need to step up and redesign their type certification scheme.
-
Fair enough, I think 737MAX will be safe once the required changes are done, notwithstanding some other failures due to Boeing's just massive bungling of this project.
You seem to be out of date. The FAA lifted the grounding order in November, subject to a list of fixes for each aircraft and training for pilots. American, with 24 MAX-8's, has been flying revenue flights since December 29th. United took delivery of its 15th MAX-9 in December and is planning to start flying them on Feb 11th. Southwest, with 31 MAX-8's, is planning to resume using them in March.
-
Fair enough, I think 737MAX will be safe once the required changes are done, notwithstanding some other failures due to Boeing's just massive bungling of this project.
You seem to be out of date. The FAA lifted the grounding order in November, subject to a list of fixes for each aircraft and training for pilots. American, with 24 MAX-8's, has been flying revenue flights since December 29th. United took delivery of its 15th MAX-9 in December and is planning to start flying them on Feb 11th. Southwest, with 31 MAX-8's, is planning to resume using them in March.
I'm not sure how my comment is out of date, it doesn't relate to regulatory action at all, but was a comment on the safety of the aircraft itself...which comes from changes done to the aircraft itself, not the regulator requiring them.
The US FAA is the only major regulatory body to have ungrounded the 737MAX (and I am not in America); it remains grounded in Europe, Canada, Australia, China and I think most other countries, though that's expected to change in the next couple of months.
-
Twas simply your use the future tense of your statement, rather than past tense.
As for Canada, they accepted the changes to the MAX last month, although the airworthiness directive is still "soon". But you just said your comment had nothing to do with regulation part, so that's beside the point.
I'm not sure exactly where EASA is on approval for the EU, but I suspect it's not far in the future.
-
Basically it incorrectly got tied to the paid AOA indicator, which is where the confusion comes from, I think. This wasn't what the design intended, but due to a misunderstanding/miscommunication between Boeing and Collins on a related trouble report, it is what ended up being implemented. Collins actually found this bug some years ago, and informed Boeing, but it was requested that Collins hold off on a fix until a future anticipated firmware update or some such weak reasoning, and Boeing never informed its customers. This is documented in the Congressional report, I haven't really seen it discussed much elsewhere.
So, if you DON'T pay for the extra indicator, the AOA disagree light NEVER goes ON? YIKES! How could Collins just SIT on that malfunction??!!??
That seems like something they really NEEDED to report to the FAA pronto!
However, I strongly believe that this concept of 'update the 50 year old airframe on the same type certificate under relaxed rules and with minimal pilot training' is fundamentally flawed.
Yes, I understand how they got here, between pressure from SouthWest Airlines and just making incremental changes on a really successful product line, and wanting to just deliver a more fuel-efficient machine, quickly, to existing customers who were chomping at the bit for a lower fuel burn.
But, YES, you are right, that keeping adding more hacks to a 50 year-old design eventually needs to end!
There was a lot else going on at Boeing that was problematic, but this is where I think the regulators really need to step up and redesign their type certification scheme.
Well, they have got the MAX back into the air, with additional fixes on top of the MCAS fixes, and are probably going to crank out a bunch more of the MAX aircraft over the next few years. But, I suspect that there's going to be a LOT more scrutiny over ANYTHING Boeing comes up with next for certification. And, then, eventually, they will need to address the narrow body market, and I can't IMAGINE it well be another hack on the 737 carcass. But, I could be wrong.
Jon
-
Currently airborne in 737MAX (2021-01-10 1839Z)
3 American Airlines passenger flights
3 Aeromexico passenger flights
4 GOL (Brazil) passenger flights
1 COPA (Panama) passeger flights
2 SouthWest (USA) repositioning flights
[attachimg=1]
-
So, if you DON'T pay for the extra indicator, the AOA disagree light NEVER goes ON? YIKES! How could Collins just SIT on that malfunction??!!??
That seems like something they really NEEDED to report to the FAA pronto!
Yup. This is beyond my understanding of the legal situation, but my guess is that Collins isn't directly beholden to the FAA. They work for Boeing from Boeing's design requirements, and it's the entire aircraft that is subject to FAA certification, and honestly they probably don't really have experts on exactly what the regulations require of Boeing to address issues like that. Should someone at Collins have blown the whistle? Maybe, but I'm willing to cut them a bit of slack, it seems like an honest mistake and they reported it to Boeing as soon as it was discovered. How Boeing let that sit when it clearly meant there were planes flying around that didn't meet their certification basis though is beyond comprehension. How serious would it have been to at least notify customers and offer a firmware update FFS, even if it was only recommended. What is that, an hour of engineer time at most, that customers can probably slot in to the rest of their maintenance schedule? I just don't get what Boeing gains from denying this information and fix to customers and pilots, it's really worrisome how they arrived at this decision for such a relatively trivial thing.
And, then, eventually, they will need to address the narrow body market, and I can't IMAGINE it well be another hack on the 737 carcass. But, I could be wrong.
Let's hope so. As I understand it, they basically canned their next-gen narrowbody project to focus on 737MAX. Maybe they start a clean-sheet design today and it's flying in 20 years, but I'm not very optimistic about that...
-
https://www.youtube.com/watch?v=5b94ouECqsc (https://www.youtube.com/watch?v=5b94ouECqsc)
-
Let's hope so. As I understand it, they basically canned their next-gen narrowbody project to focus on 737MAX. Maybe they start a clean-sheet design today and it's flying in 20 years, but I'm not very optimistic about that...
Boeing have the problem that they've tried to use the 737NG and 737-MAX series to simultaneously replace the 1500 mi / 125 passenger 737-200 and the 4500mi 190-220 passenger 757-200/767-200 with the same airframe, and you're running into issues that it's hard to do both effectively.
I think if they go 'clean sheet', they may end up having to make two aircraft; or work with another vendor (Embraer?) to fill the smaller side.
Same thing is happening on the prop-side of the world, no one at all competes with ATR and the ATR42 at the 40-50 seat size, with DHC only making 75 seater DHC8-400s. And at the smaller 20 seat size, the only current production aircraft I can think of are the new Cessna 408 & DHC6-400s both of which are really special purpose (the former being a cargo hauler and the latter highly optimized for STOL/rugged operations), which isn't really ideal to replace things like the B1900s of the world.
-
Same thing is happening on the prop-side of the world, no one at all competes with ATR and the ATR42 at the 40-50 seat size, with DHC only making 75 seater DHC8-400s. And at the smaller 20 seat size, the only current production aircraft I can think of are the new Cessna 408 & DHC6-400s both of which are really special purpose (the former being a cargo hauler and the latter highly optimized for STOL/rugged operations), which isn't really ideal to replace things like the B1900s of the world.
Seems like a DC-3 would be a nice fit there, maybe they should put those back into production. Lots of planes are faster and bigger and more luxurious but nothing I can think of has really quite hit that perfect sweet spot that has kept dozens of DC-3 airframes in revenue service for ~80 years.
-
I thought that DC-3s are still flying because there were so many made that they'll never run out of old planes to take parts from. If we're talking about safety, I don't think a unpressurized plane built to safety standards from 80 years ago would be appealing to current operators.
I think there are a few companies that have rebuilt DC-3s and modernized them with turboprop engines. If they made sense for airlines, we would see them everywhere.
I haven't looked up the regulations myself, but I think there is a difference between small planes with up to 19 passengers versus the big airliners. This would explain the hole in the market between 19 and 50 passengers.
If an airline has to meet tougher safety standards and have higher levels of staffing per flight, it might be impossible to make money flying a 20 or 30 passenger plane.
-
They're already running out of parts, prices on used DC-3s have gone up sharply in recent years but they keep going because they are still relatively affordable for a plan of that size and capability. It probably wouldn't make sense to start producing them again, given all the regulations I'm guessing it would be impossible to build them the same as the old ones, I can dream though. It's hard to think of an aircraft that is more timeless and classic, it's the grandfather of modern airliners. A great many of the planes meant to replace it went out of revenue service decades ago, many have no airworthy examples remaining at all.
-
They're already running out of parts, prices on used DC-3s have gone up sharply in recent years but they keep going because they are still relatively affordable for a plan of that size and capability. It probably wouldn't make sense to start producing them again, given all the regulations I'm guessing it would be impossible to build them the same as the old ones, I can dream though. It's hard to think of an aircraft that is more timeless and classic, it's the grandfather of modern airliners. A great many of the planes meant to replace it went out of revenue service decades ago, many have no airworthy examples remaining at all.
The first plane I ever flew on was a DC-3. I was 5 and it was very exciting, flying alone - taken care of by a stewardess in full, impeccably pressed uniform, with impossibly shiny brass buttons and badges! I remember being awestruck at the thunder of the engines as they started and revved up, massive amounts of blue and black smoke (I guess fuel and piston oil control rings were "good enough for Australia" back then, and mufflers etc. was not something real men or women had any use for whatsoever)... I remember the feeling of the small miracle as the plane accelerated down the runway with incredible noise, watching the ground disappearing under the plane... I still feel that way at every take-off and always sit by the window for that reason alone, even if modern planes are a quite anodyne experience compared to a DC-3! :D
-
I thought that DC-3s are still flying because there were so many made that they'll never run out of old planes to take parts from. If we're talking about safety, I don't think a unpressurized plane built to safety standards from 80 years ago would be appealing to current operators.
I think there are a few companies that have rebuilt DC-3s and modernized them with turboprop engines. If they made sense for airlines, we would see them everywhere.
We're down to a few hundred in active service now, out of the 16000 DC-3/C-47 variants that were built. But they fill a niche. The tail-dragger configuration is simply superior at operating on short rough fields compared to modern aircraft of similar size. Rough fields were common in the era/war they were designed for.
As for turboprop conversions, the Jeopardy clue would be: This aircraft worth $300,000 is now worth $8,000,000. Answer: What is a DC-3 turbo-prop conversion?
Why? A lot more than the engine has to be upgraded to be properly certified, and it's nearly all hand labor...but you end up with a like-new aircraft you can fly another 50 years. So your commercial reality has to be pretty strong to invest that much to replace something that is still working.
Here's the longer story on that: https://www.youtube.com/watch?v=GfgC5DROP-M (https://www.youtube.com/watch?v=GfgC5DROP-M)
-
Don't the airframes have a limited number of take-offs and landings, like modern planes? Or are they simply so strong and over-engineered that it isn't an issue?
-
Don't the airframes have a limited number of take-offs and landings, like modern planes? Or are they simply so strong and over-engineered that it isn't an issue?
No, the DC-3 requires regular inspection and maintenance like every other aircraft. However, your implication that airplanes have to be discarded at a certain point is not correct. Barring obvious calamities, aircraft can be kept flying for generations, so long as they are properly maintained. Airlines get rid of old planes and buy new ones for economic/business/pilot training reasons, not because the old ones are suddenly unusable.
Modern or antique, there are all sorts of maintenance requirements triggered by hours of use, cycles, landings, age, or unusual events. All documented in the maintenance manual with updates from airworthiness directives over the years. Some things you just have to inspect, some things you test, some things you overhaul, some things you replace.
-
Hum, aircraft structure is designed and certified for a given number of cycles (a cycle is complete flight, with take-off and landing). Once this number is achieved, either the aircraft manufacturer make additional tests and computations to certify more cycles, either the aircraft is grounded for ever.
-
The old DC3 has no pressurized cabin, which reduces the stress on the structure. It was also made to land on not so good runways. The stress from landings can vary a lot - so a fixed number of cyles does not make much sense with those old planes. So here it is more like regular inspections until cracks can no longer relaired.
It can make sense for a modern plane build to weight, where the stress from the pressure change can be the limiting factor. There a limited number of cycles makes absolute sense.
With the current situation, there may not be much demand for additional new planes in the next 20 years and chances are the airlines are short on money too. With the current reduced fligh plans they can scrap the old ones without buying new. For Boing and Airbus it is likely more about canceled orders for the 737 and A320. They still have a lot one the books - but what is it good for if the airlines can't pay.
If at all it would be about more fuel efficient models, in case the oil price and maybe taxes would go up.
-
It can make sense for a modern plane build to weight, where the stress from the pressure change can be the limiting factor. There a limited number of cycles makes absolute sense.
Newer aircraft like the 787 seem to be going in the direction of a higher cabin pressure which seems to contradict the goal of reducing stress on the structure to reduce weight and increase lifetime. I would have thought that lowering the cabin pressure and then using an oxygen concentrator to increase the partial pressure of the oxygen would be a good way to go, would be interesting to find out if it's merely a cost issue or if the weight/power use of the oxygen concentrator cancels out the benefit.
-
Don't the airframes have a limited number of take-offs and landings, like modern planes? Or are they simply so strong and over-engineered that it isn't an issue?
The "limited number of take-offs and landings" you are referring to is the maximum flight cycles that is applicable pressurized aircraft.
Typically, an unpressurized aircraft does not have a limited number of flight cycles imposed by its type certificate.
:)
-
FAA safety engineer goes public to slam the agency’s oversight of Boeing’s 737 MAX: https://www.seattletimes.com/business/boeing-aerospace/faa-safety-engineer-goes-public-to-slam-the-agencys-oversight-of-boeings-737-max/ (https://www.seattletimes.com/business/boeing-aerospace/faa-safety-engineer-goes-public-to-slam-the-agencys-oversight-of-boeings-737-max/)
-
The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.
https://en.m.wikipedia.org/wiki/Gimli_Glider
-
The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.
https://en.m.wikipedia.org/wiki/Gimli_Glider
using that as a reason not to fly makes no sense, flying is statistically very safe compared to other forms of transport. And unlike
almost everything else every single accident and near accident is investigated to find the reasons and what measures to takes to
prevent it from happening again
-
The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.
https://en.m.wikipedia.org/wiki/Gimli_Glider
This incident was made into a movie, right? - The incident should never have happened, but what a save!
-
The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.
https://en.m.wikipedia.org/wiki/Gimli_Glider
That's a totally inappropriate comparison. The Gimli Glider was an out-of-fuel situation at high altitude with a controllable airplane that could still glide for 50+ miles, even without engines. The Challenger, which I watched live on a 32" TV (big-screen for 1986), was an explosion due to a failed seal on a solid booster rocket, and there was literally nothing the crew could do about it. Not the same thing at all!
A much better match to the Challenger would be TWA flight 800 ten years later. That was a fuel tank explosion that destroyed the 747. Nothing the crew could do about it, although they did notice crazy readings several minutes beforehand.
In any case, all of those things happened 25-35 years ago and the aircraft industry survived just fine. Recent events that mangled the travel industry have had a much bigger impact, but the aircraft industry is going to survive that as well.
-
The story of the Gimli Glider truly shows how fragile the whole commercial aircraft industry really is. Everyone screwed up in this story. The only reason it didn’t turn out like the Challenger disaster was sheer dumb luck and a cool under pressure crew. Read it and weep. This is why I have always refused to fly.
https://en.m.wikipedia.org/wiki/Gimli_Glider
You're in far more danger on the road from yourself, let alone everyone else, than you are on a commercial flight.
-
A much better match to the Challenger would be TWA flight 800 ten years later. That was a fuel tank explosion that destroyed the 747. Nothing the crew could do about it, although they did notice crazy readings several minutes beforehand.
With the benefit of hindsight they could have pulled the appropriate circuit breaker(s) to kill power to the center tank fuel pumps, but I can hardly fault them for not realizing what was going on at the time and taking that action. They couldn't reasonably have been expected to prevent the accident but they still had more control over the situation than the Challenger crew, who had no indication whatsoever that anything was wrong until it blew up.
-
It can make sense for a modern plane build to weight, where the stress from the pressure change can be the limiting factor. There a limited number of cycles makes absolute sense.
Newer aircraft like the 787 seem to be going in the direction of a higher cabin pressure which seems to contradict the goal of reducing stress on the structure to reduce weight and increase lifetime. I would have thought that lowering the cabin pressure and then using an oxygen concentrator to increase the partial pressure of the oxygen would be a good way to go, would be interesting to find out if it's merely a cost issue or if the weight/power use of the oxygen concentrator cancels out the benefit.
AFAIK it's the composite construction that allows for the higher cabin pressure. Composite materials have different fatigue characteristics than aluminum. I don't know how the lifespan compares but I assume they have calculated everything and can choose exactly how strong to make each individual component in order to achieve an acceptable number of flight cycles at the desired cabin pressure. Weight, lifetime, passenger comfort, pick any two to optimize for.
-
The first plane I ever flew on was a DC-3. I was 5 and it was very exciting, flying alone - taken care of by a stewardess in full, impeccably pressed uniform, with impossibly shiny brass buttons and badges! I remember being awestruck at the thunder of the engines as they started and revved up, massive amounts of blue and black smoke (I guess fuel and piston oil control rings were "good enough for Australia" back then, and mufflers etc. was not something real men or women had any use for whatsoever)... I remember the feeling of the small miracle as the plane accelerated down the runway with incredible noise, watching the ground disappearing under the plane... I still feel that way at every take-off and always sit by the window for that reason alone, even if modern planes are a quite anodyne experience compared to a DC-3! :D
When radial engines sit, oil tends to pool in the lower cylinders and slowly seeps past the rings. When starting the engine after it has rested you have to be careful to turn it over several rotations before turning on the magnetos so that you don't hydrolock a cylinder. The oil that has seeped past the rings ends up in the exhaust manifold so it's common to get a lot of smoke from a cold start. Jets are cool and all, but nothing comes close to those big old radial piston engines for me. The sound bristles the hair on the back of my neck, it's like a mob of Harley Davidson motorcycles. I've never had the fortune of a ride on one but I did get to sit in the pilot's seat of a DC-3 on the ground at an air show a few years ago and saw it flying later.
-
The first plane I ever flew on was a DC-3. I was 5 and it was very exciting, flying alone - taken care of by a stewardess in full, impeccably pressed uniform, with impossibly shiny brass buttons and badges! I remember being awestruck at the thunder of the engines as they started and revved up, massive amounts of blue and black smoke (I guess fuel and piston oil control rings were "good enough for Australia" back then, and mufflers etc. was not something real men or women had any use for whatsoever)... I remember the feeling of the small miracle as the plane accelerated down the runway with incredible noise, watching the ground disappearing under the plane... I still feel that way at every take-off and always sit by the window for that reason alone, even if modern planes are a quite anodyne experience compared to a DC-3! :D
When radial engines sit, oil tends to pool in the lower cylinders and slowly seeps past the rings. When starting the engine after it has rested you have to be careful to turn it over several rotations before turning on the magnetos so that you don't hydrolock a cylinder. The oil that has seeped past the rings ends up in the exhaust manifold so it's common to get a lot of smoke from a cold start. Jets are cool and all, but nothing comes close to those big old radial piston engines for me. The sound bristles the hair on the back of my neck, it's like a mob of Harley Davidson motorcycles. I've never had the fortune of a ride on one but I did get to sit in the pilot's seat of a DC-3 on the ground at an air show a few years ago and saw it flying later.
The "mob of Harley Davidsons" is about right. I was sitting behind the engine, on the left side of the plane. The exhaust was a HUGE letterbox shaped duct and the noise was incredible - would never be permitted today - normal conversation was not possible at any time during the journey! It was clear to me even as a child that we were dealing with serious horsepower when the engines were started - but even that did not prepare me for the incredible sheer energy of those engines during the take-off! I could see the smoke being blown by the propeller, I remember thinking the propellers were "rowing" in the air at incredible speed... a kind of high speed rowboat!
I sat with a silly grin the whole journey... the whole thing is seared in my mind, I recall vents opening on the engine cowl and closing again as the plane started take-off, presumably to allow more cooling when the plane is stationary. If I had been a bit older, I would probably have paid a little more attention to the pretty stewardess!
There have only been a few incidents since then where engines have made my hair bristle: one was a steam locomotive starting from a stand-still at the platform, pulling a very long train... the sheer brute force made the whole platform shake, you could literally see the locomotive straining at its leash as it leaned into its suspension with BRUTAL strength! Total awesomeness... I definitely 'get' steam train nuts...
-
I sat with a silly grin the whole journey... the whole thing is seared in my mind, I recall vents opening on the engine cowl and closing again as the plane started take-off, presumably to allow more cooling when the plane is stationary. If I had been a bit older, I would probably have paid a little more attention to the pretty stewardess!
There have only been a few incidents since then where engines have made my hair bristle: one was a steam locomotive starting from a stand-still at the platform, pulling a very long train... the sheer brute force made the whole platform shake, you could literally see the locomotive straining at its leash as it leaned into its suspension with BRUTAL strength! Total awesomeness... I definitely 'get' steam train nuts...
The vents are called cowl flaps and as you guessed are there to regulate cooling airflow to maintain proper operating temperature of the engines. They're controlled manually by the pilot or in the case of larger planes the flight engineer.
Pretty girls can be found almost anywhere, there are more interesting things to see on an airplane, especially back in the era where it was really something special.
Yeah steam locomotives and trains in general are pretty cool. I'm not what would be called a railfan but it's definitely something I'll stop and admire if I see one passing by. Railroad engineer is one of several careers that I think would be fun in another life. It's too bad it isn't the sort of thing you can really do for a few years and then go back to something else.