Lion Air crash: Jakarta Boeing 737 'had prior instrument error'

[Mechatrommer]

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.

[mikeselectricstuff]

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/

[Hyper_Spectral]

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

[HighVoltage]

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/

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.
 

[GeorgeOfTheJungle]

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

[MT]

As a conspiracy theorist,

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.

[KL27x]

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.

[Brumby]

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.

[GeorgeOfTheJungle]

"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?

[floobydust]

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/

[KL27x]

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.

[GeorgeOfTheJungle]

GoJ, it sounds like you are beginning to entertain the possibility the pilots did not screw up?

No... :-)



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)

[KL27x]

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. 

[GeorgeOfTheJungle]

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.

[KL27x]

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."

[ogden]

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.

[KL27x]

^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.

[ogden]

^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.

[KL27x]

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 ^.

[GeorgeOfTheJungle]

[...] 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 :

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?

[GeorgeOfTheJungle]

BTW this is interesting, a 737 NG "users manual":
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.

[dzseki]

BTW this is interesting, a 737 NG "users manual":
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.

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...

[RandallMcRee]

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

[tooki]

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

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.

[floobydust]

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.