Ethiopian airliner down in Africa

[infrequentflyer789]

Originally Posted by 737 Driver

All this being said, one of the causal factors of these accidents is that the pilots let the aircraft so far out of trim in the first place. It is absolutely clear from the data (both ET302, and both LA610 flights) that the pilot actuated stab trim stopped and reversed the MCAS trim input every time it was used. As powerful as MCAS was, it could not overcome the strength inherent in the Captain's left thumb - if he had chosen to use it.

What do you make of this from ET:

05:40:27 - the Captain advised the First-Officer to trim up with him

Bearing in mind preceding it is an ineffective (in timing and duration compared to 1st MCAS input) period of manual ANU trim, and following it is a period of manual trim that both interrupts the 2nd MCAS input, is constant/continuous and reverses it (but doesn't reverse the first MCAS input).

It sounds (to this non-pilot engineering type) awfully like the Captain's left thumb (or it's switch) does not have the Captain's confidence, and not at all like he has just not "chosen to use it".

Or, put another way, under what circumstances as a 737 driver would you ask your co-driver to "trim up (or down) with you"? If the answer is "don't know any circumstances " or "would never do that", then WTF was going on in the ET cockpit to trigger that request?

[FrequentSLF]

Originally Posted by infrequentflyer789

What do you make of this from ET:

05:40:27 - the Captain advised the First-Officer to trim up with him

Bearing in mind preceding it is an ineffective (in timing and duration compared to 1st MCAS input) period of manual ANU trim, and following it is a period of manual trim that both interrupts the 2nd MCAS input, is constant/continuous and reverses it (but doesn't reverse the first MCAS input).

It sounds (to this non-pilot engineering type) awfully like the Captain's left thumb (or it's switch) does not have the Captain's confidence, and not at all like he has just not "chosen to use it".

Or, put another way, under what circumstances as a 737 driver would you ask your co-driver to "trim up (or down) with you"? If the answer is "don't know any circumstances " or "would never do that", then WTF was going on in the ET cockpit to trigger that request?

Very good point!
i would also ask to the experts, what the FDR records? The thumb switch? The manual command to the brushless motor? Or the effective running of the motor?
Furthermore, since the MAX was the first aircraft with MCAS which agency should oversight the FDR signals recording? Spoilers are FBW, MACS is lingering in the background... how difficult will be for investigators to interprete recordjngs?

[737 Driver]

Originally Posted by Bend alot

With respect-

You were the only pilot that responded to what "would you do" that maintained the flying pilot position. You gave very little tasks to the non flying pilot and you even did not acknowledge the input that they would have given you. Your feed back was of a one man crew.

Both others that replied handed over to the FO to fly, I expect as they had the accurate instruments not just air speed but pitch - the pilots pitch was incorrect!

Again the pilots pitch was incorrect.

With respect -

As prelude, we need to correct one misunderstanding here. There was nothing wrong with the attitude indicators. The only manner in which the Captain’s pitch was incorrect or not was whether he established the correct pitch or not on his fully functioning attitude indicator.

There is no single right answer to this malfunction. Much depends on how quickly the crew perceives what is actually transpiring, what is working, and what isn’t. The major test of what responses were acceptable is whether those actions ultimately resulted in the safe landing of the aircraft.

The setup for this scenario was what would I have done if I were placed in the Ethiopian Captain’s position. May I remind you that he was given not only a malfunctioning aircraft but also a 350-hour First Officer? One of the important decisions a Captain must make, once the situation is stabilized, is to designate the flying and non-flying pilot. Yes, with a reasonably experienced First Officer, it would have been prudent to designate that person as the flying pilot once it was determined that he had the better instruments. However, it should be stated that there are certain real challenges to flying an aircraft with an AOA that is generating an erroneous stall signal due to the various ancillary system effects (I won’t detail them here, so you just need to accept my word on that). Unless this particular 350-hour FO had previously demonstrated to me that he had strong hand flying skills, then it is very likely that I would have continued to fly the aircraft for much of the remaining flight.

[737 Driver]

Originally Posted by wheelsright

"No evidence" is a commonly used phrase used to justify all manner of absurdity (usually by politicians). The absence of evidence does not rule in or rule out anything.

"It is absolutely clear from the data (both ET302, and both LA610 flights) that the pilot actuated stab trim stopped and reversed the MCAS trim input every time it was used. As powerful as MCAS was, it could not overcome the strength inherent in the Captain's left thumb" It is not absolutely clear at all. The FDR does not track the thumbswitch position as far as I know. Thus, it cannot be said with certainty that there were not additional electric trim up inputs that had no effect. Your assumption seems to be based on the accuracy of Boeings publications. I do not think that any pilot, even a very bad pilot, would not make further electric trim up corrections under the circumstances. For these reasons there remain doubts in my mind. In the case of ET302 it seems the crew reactivated electric trim in desperation... following that action it is difficult to believe that they did not do so to apply constant electric trim up via the thumb switch. It is a puzzle what actually happened, but unless you KNOW what the pilots ACTUALLY did it is mere speculation rather than being "absolutely clear".

The DFDR traces show not only pilot and automation inputs on separate tracks, they also show whether the stab moved in response. There is even one example where MCAS is shown trying to make an input but the stab does not move because the stab trim switches were in the cutout position. Otherwise, every time that either the pilot or the automation made a stab trim input, then the stab moved as one would expect. I do not know whether the DFDR picks up the pilot trim signal directly from the switch or from somewhere else, but there were plenty of pilot inputs that corresponded to a stab movement. To conclude that the yoke trim switch suddenly stopped working requires a much greater leap of faith than a conclusion that it was used ineffectually.

[737 Driver]

Originally Posted by infrequentflyer789

What do you make of this from ET:

05:40:27 - the Captain advised the First-Officer to trim up with him

Bearing in mind preceding it is an ineffective (in timing and duration compared to 1st MCAS input) period of manual ANU trim, and following it is a period of manual trim that both interrupts the 2nd MCAS input, is constant/continuous and reverses it (but doesn't reverse the first MCAS input).

It sounds (to this non-pilot engineering type) awfully like the Captain's left thumb (or it's switch) does not have the Captain's confidence, and not at all like he has just not "chosen to use it".

Or, put another way, under what circumstances as a 737 driver would you ask your co-driver to "trim up (or down) with you"? If the answer is "don't know any circumstances " or "would never do that", then WTF was going on in the ET cockpit to trigger that request?

There is abundant information here to show that this crew was absolutely overwhelmed by the circumstances they faced. There are many, many head scratchers that simply defy explanation if your going in assumption is that the crew was in control of the situation. They were not. Rather, the situation was clearly in control of them. So you must pardon me if I do not attempt to provide a rational explanation for many of their actions.

[MemberBerry]

Earlier I was comparing Boeing's MCAS with Volkswagen's emissions test defeat device. I found this old New Yorker article, from 2015, hypothesizing how Volkswagen may have got there:

https://www.newyorker.com/business/c...swagen-scandal

They say it may not have necessarily been an explicit management decision saying "let's cheat", but many small incremental changes that individually didn't seem a big deal (normalization of deviance):

If the same pattern proves to have played out at Volkswagen, then the scandal may well have begun with a few lines of engine-tuning software. Perhaps it started with tweaks that optimized some aspect of diesel performance and then evolved over time: detect this, change that, optimize something else. At every step, the software changes might have seemed to be a slight “improvement” on what came before, but at no one step would it necessarily have felt like a vast, emissions-fixing conspiracy by Volkswagen engineers, or been identified by Volkswagen executives. Instead, it would have slowly and insidiously led to the development of the defeat device and its inclusion in cars that were sold to consumers.

Initial reports mentioned that at least 30 Volkswagen managers were involved. And now, 4 years later, some of them have already been sentenced to jail time. So, at least in Volkswagen's case, it seems it was a bit more than just "normalization of deviance".

[737 Driver]

Originally Posted by fdr

The crew did try to fly the plane, they didn't recognise the problem, they didn't comprehend what the situation was promptly, and when breaking the manual trim process they did not project the state forward as a result of that action, due to inadequate information and training. Were they flying the plane? they were, but they didn't know they had brought a knife to a gun fight.

Which is precisely why, when presented with an undesired aircraft state, unknown or ambiguous malfunction, or a loss of situational awareness, the flying pilot must be ready and able to Turn off the magic, Set the Pitch, Set the Power, Trim the aircraft, Monitor the performance, and Move the aircraft to a safe altitude. You do not have to know what is going on. You do need to know how to stabilize the aircraft and place it in a safe position so you then have the time to figure out what is going on.

[MemberBerry]

Originally Posted by 737 Driver

Which is precisely why, when presented with an undesired aircraft state, unknown or ambiguous malfunction, or a loss of situational awareness, the flying pilot must be ready and able to Turn off the magic, Set the Pitch, Set the Power, Trim the aircraft, Monitor the performance, and Move the aircraft to a safe altitude. You do not have to know what is going on. You do need to know how to stabilize the aircraft and place it in a safe position so you then have the time to figure out what is going on.

The first step in your mantra is "turn off the magic". What Boeing did by implementing MCAS severely undermines that first step, because they added an additional bit of "magic", that can't be turned off using the old procedures (A/P off, A/T off, FD off). Instead, turning off this bit of "magic" requires disabling manual electric trim as well, with the cutout switches.

I think it wouldn't hurt if Boeing would implement some way to disable automatic trim independently from manual electric trim. Something that can disable both STS and MCAS without forcing you to use the trim wheels for the rest of the flight.

Since making significant changes to the cockpit like adding switches is probably out of the question, maybe there should be a way to completely disable automatic trim, using existing switches. For example using the existing cutout switches. Placing them in the cutout position, waiting a few seconds, then switching them back to normal could be used as a way to disable automatic trim, but leave manual electric trim functional. That would require just a software change.

Then your mantra would work just fine, if you include this additional sub-step of "Auto-Trim Off" as part of "turn off the magic".

[FrequentSLF]

Originally Posted by 737 Driver

Which is precisely why, when presented with an undesired aircraft state, unknown or ambiguous malfunction, or a loss of situational awareness, the flying pilot must be ready and able to Turn off the magic, Set the Pitch, Set the Power, Trim the aircraft, Monitor the performance, and Move the aircraft to a safe altitude. You do not have to know what is going on. You do need to know how to stabilize the aircraft and place it in a safe position so you then have the time to figure out what is going on.

with all respect, Sir
turn off magic... that was possible on previous 737, before max... lets do not talk about AB.
MAX is different from any other 737, you cannot turn off magic... in case of trim stab... you turn off power! Not magic, Sir, turn off power, and manual wheel is smaller than in the 400s...hence higher force required to crank.
still with all due respect Sir, how hard is to move the trim manually on a MAX? (If you ever tried)

[737 Driver]

Originally Posted by MemberBerry

The first step in your mantra is "turn off the magic". What Boeing did by implementing MCAS severely undermines that first step, because they added an additional bit of "magic", that can't be turned off using the old procedures (A/P off, A/T off, FD off). Instead, turning off this bit of "magic" requires disabling manual electric trim as well, with the cutout switches.

I think it wouldn't hurt if Boeing would implement some way to disable automatic trim independently from manual electric trim. Something that can disable both STS and MCAS without forcing you to use the trim wheels for the rest of the flight.

Since making significant changes to the cockpit like adding switches is probably out of the question, maybe there should be a way to completely disable automatic trim, using existing switches. For example using the existing cutout switches. Placing them in the cutout position, waiting a few seconds, then switching them back to normal could be used as a way to disable automatic trim, but leave manual electric trim functional. That would require just a software change.

Then your mantra would work just fine, if you include this additional sub-step of "Auto-Trim Off" as part of "turn off the magic".

I assume that you are aware that there are other potential sources of uncommanded and undesired stabilizer trim movement besides MCAS? We do not have separate disconnects for them either. The runaway stab trim procedure is completely and absolutely agnostic as to the source of the uncommanded movement, nor should the flight crew waste precious time trying to diagnosis the source.

As to the mantra, you may have noted that one of the steps was “Trim the Aircraft.” At all times, the MCAS input could be stopped and reversed by the use of Main Electric Trim. The flying pilot was fully capable of countering every MCAS input until such time that the crew got around to executing the runaway stab trim procedure.

BTW, it is not procedural to fiddle with the cutout switches once they have been used.

[737 Driver]

Originally Posted by FrequentSLF

with all respect, Sir
turn off magic... that was possible on previous 737, before max... lets do not talk about AB.
MAX is different from any other 737, you cannot turn off magic... in case of trim stab... you turn off power! Not magic, Sir, turn off power, and manual wheel is smaller than in the 400s...hence higher force required to crank.
still with all due respect Sir, how hard is to move the trim manually on a MAX? (If you ever tried)

Please read and heed the entire mantra. The first step is to turn off the magic. A few steps later is “Trim the Aircraft”. That step is sufficient to take care of MCAS until the runaway trim procedure is executed. The manual trimming has always been a problem on multiple Boeings - if you let it get grossly out of trim. The crew had the ability to not let it get there.

I’m sorry, but this is too much like the story of the kid who killed his parents and then requested mercy before the Court because he was an orphan. The lack of application of basic airmanship skills placed this aircraft in a situation where basic airmanship skills were no longer sufficient to save the ship. Too many people are looking at the five minute mark and declaring the aircraft to be unflyable without much regard as to what happened in the previous 4 minutes and 59 seconds.

[FrequentSLF]

Originally Posted by 737 Driver

Please read and heed the entire mantra. The first step is to turn off the magic. A few steps later is “Trim the Aircraft”. That step is sufficient to take care of MCAS until the runaway trim procedure is executed. The manual trimming has always been a problem on multiple Boeings - if you let it get grossly out of trim. The crew had the ability to not let it get there.

I’m sorry, but this is too much like the story of the kid who killed his parents and then requested mercy before the Court because he was an orphan. The lack of application of basic airmanship skills placed this aircraft in a situation where basic airmanship skills were no longer sufficient to save the ship. Too many people are looking at the five minute mark and declaring the aircraft to be unflyable without much regard as to what happened in the previous 4 minutes and 59 seconds.

grossly out of trim? I do not the FDR traces, but if i recall well was 2 MCAS events and trim was at 2.1. So 2 degrees, max 3 out of trim...
your mantra says turn off magic first.., so... how long before you decide to trun off? 9 seconds? 2.5 degress of trim... of you saying that you so brilliant that in 1 second can decide is a runaway trim and hit the cut off?
9 seconds and ypu are grosssly out of trim, and no power. You stated earlier, before cut off trim back...but how that works with turn off magic? Those are your words...turn off magic, but before cutting off power trim back... that is impossible on max.
maybe you need a new mantra

[MemberBerry]

Originally Posted by 737 Driver

I assume that you are aware that there are other potential sources of uncommanded and undesired stabilizer trim movement besides MCAS? We do not have separate disconnects for them either. The runaway stab trim procedure is completely and absolutely agnostic as to the source of the uncommanded movement, nor should the flight crew waste precious time trying to diagnosis the source.

As to the mantra, you may have noted that one of the steps was “Trim the Aircraft.” At all times, the MCAS input could be stopped and reversed by the use of Main Electric Trim. The flying pilot was fully capable of countering every MCAS input until such time that the crew got around to executing the runaway stab trim procedure.

BTW, it is not procedural to fiddle with the cutout switches once they have been used.

I'm aware there are other sources, like the A/P, but turning off the A/P is already possible, so I didn't mention it. I already mentioned STS, and suggested that there should be a way to disable both STS and MCAS, since they are still functional even when the A/P is off. And you should be able to do that without affecting anything else.

Of course you could also have a stabilizer runaway involving the manual electric trim, that would require disabling it with the cutout switches to stop it. But from what I read such a runaway is less likely compared to an MCAS runaway. I didn't hear anyone here saying they experienced such a stabilizer runaway on the 737.

As to not wasting time troubleshooting, actually the existing trim runaway memory items involve troubleshooting. First they tell you to turn off the A/P and A/T. If that doesn't work, use the cutout switches. If that doesn't work, hold and grasp the trim wheels. If they didn't want you to troubleshoot, they would just tell you to do all 3 steps immediately, without waiting after each step to see if it fixes the issue.

As to fiddling with the cutout switches after being used, it might not be procedural, although the memory items do not mention that explicitly. They do explicitly mention not reenabling the A/P and A/T. If not fiddling with them is so important, it should have been explicitly mentioned.

And, in any case, procedures are written by humans, and can and have been modified a lot of times in the past to make them better.

[Uplinker]

Originally Posted by 737 Driver

Which is precisely why, when presented with an undesired aircraft state, unknown or ambiguous malfunction, or a loss of situational awareness, the flying pilot must be ready and able to Turn off the magic, Set the Pitch, Set the Power, Trim the aircraft, Monitor the performance, and Move the aircraft to a safe altitude. You do not have to know what is going on. You do need to know how to stabilize the aircraft and place it in a safe position so you then have the time to figure out what is going on.

+1 Very well put

But this needs training and reinforcement in the SIM. It is not enough - in these days of CBTs and multiple choice exams - to assume that all pilots are capable of this without training. Sad but true. So much time is taken up with other things in SIM details that the basics are being assumed to be present rather than being actually tested and practised.

[737 Driver]

Originally Posted by MemberBerry

As to not wasting time troubleshooting, actually the existing trim runaway memory items involve troubleshooting. First they tell you to turn off the A/P and A/T. If that doesn't work, use the cutout switches. If that doesn't work, hold and grasp the trim wheels. If they didn't want you to troubleshoot, they would just tell you to do all 3 steps immediately, without waiting after each step to see if it fixes the issue.
.

All that “troubleshooting” takes less than 5 seconds.

[capngrog]

"05:40:27 - the Captain advised the First-Officer to trim up with him"

The above quote is from frequentflyer789's Post #4882; however, the quote itself is merely a narrative account of cockpit conversations and is not from a transcript of the actual cockpit conversations. Has anyone seen/read a transcript of the CVR tapes? Will such a transcript be forthcoming?

Cheers,
Grog

[VFR Only Please]

Originally Posted by 737 Driver

The Ethiopian Captain (…) was given (…) a 350-hour First Officer.

Apparently there are 200-hour pilots out there flying nuclear-armed aircraft. So I've heard. Simulators have come a long way, thousands of hours of teaching people to fly single-engine airplanes really isn’t the greatest preparation for airline flying, and the CVR shows it was the Ethiopian FO’s suggestion to hit the cutout switches in the first place.

Originally Posted by 737 Driver

It is not procedural to fiddle with the cutout switches once they have been used.

It also isn’t procedural having the terrain fast rising up out the window to smite thee. Desperate times maybe explain desperate measures.

At all events, there's 0.6% of the worldwide Max fleet gone in the space of five months. No survivors. My two cents: Boeing finally broke the 737 but good by dint of finally overtweaking it. Having done that, they took the stall-happy result and -- on the cheap -- hastily stuck a bandaid on it. Now they and their furious customers are wedded to this Frankenplane, so Boeing is working on a New & Improved Extra-Special Bandaid.
Onion News defined MCAS as "software designed to place all the blame on airline pilots".

[derjodel]

Originally Posted by 737 Driver

Okay, Sully wasn't piloting a 737, but let's say he did. Somehow I just don't think Sully would have allowed his stab trim to run for 9 continuous seconds (that would be 37 spins of the trim wheel) before doing something about it, say like hitting the yoke trim switch with his left thumb. I certainly don't think he would let that happen twice. Maybe we should also note that Sully wasn't piloting Lion Air 610 the day before the accident (same aircraft, different crew in the very first documented case of the MCAS malfunction), and yet they still managed to figure out that when an automated system puts in some stab trim you don't want, it is entirely possible to take it right back out again.

Perhaps one day Sully would offer his perspective. All we know with certainty is that he claims there is a „human factor“ which needs to be takin into account.

i wonder, in case he crashed, how many pilot s here would badmouth him to not turn to la guardia the second after the birdstrike. Well, luckily we won‘t know that.

but in case of ET, it‘s not exactly fair to say they did nothing. Captain called control problems immediatelly and pulled the stick back to counter the trim. At 5:39:55 AP disengaged and mcad kicked in. At 5:40:35 trim cotout was done. Not 35, but 40 seconds. Ok, their human factor was worse than Sullys. But it is nontheless, human factor. Humans are not machines and machines need to be designed in a way to anticipate delayed corrective response.

Btw, Sully switched APU on although it was NOT on the checklist. ET crew tried to re-engage AP. In case Sully failed, i bet he would have been crucified for not following the ckecklist.

very interesting thing, human bias.

[Kerosene Kraut]

Blaming the pilots for some imperfect systems layout sounds a bit unfair to me.

[derjodel]

Originally Posted by Kerosene Kraut

Blaming the pilots for some imperfect systems layout sounds a bit unfair to me.

for the pilots, it helps building the (false?) self- confidence. “Can’t happen to me”. The alternative is to develop fear of flying. So it‘s an understandable subconscious strategy.

for some other entities, the reason is simply monetary.