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

[Kjelt]

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.

[djacobow]

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.

[KL27x]

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.

[Brumby]

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.

[Brumby]

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.)

[KL27x]

^ 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.

[julianhigginson]

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

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.

[Brumby]

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.

[djacobow]

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.

[KL27x]

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.

[Brumby]

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.

[MT]

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.

[KL27x]

In the words of Mike Tyson, "Everyone has a plan, until they get punched in the face."   

[tooki]

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.

[KL27x]

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.

[tooki]

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.

[KL27x]

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.

[Brumby]

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".

[KL27x]

^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.

[Nusa]

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.

[KL27x]

^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. 

[ogden]

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 This is criminal negligence from Boeing, regulators and airlines: https://www.aviationcv.com/aviation-blog/2019/shocking-facts-boeing-737max-crash

[BravoV]

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. 

[KL27x]

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.

[ogden]

At high angle of attack, the plane isn't flying nose first.

Right.