737 Stuck Manual Trim Technique
I confess I don't understand your objections to what I am saying. If a stall strip comes off an airplane in flight and then the pilot subsequently finds on approach that the wing is dropping, should he give up? Just let the airplane fly into the ground? I would posit that there are pilots out there just waiting for that opportunity. He does not have to know why the wing is dropping all he has to do is react and recover.
If a pilot gets ice on the tailplane and experiences tailplane stalling should he think "I have not been trained to handle this so I just give up?" If a pilot finds that after lift off his airspeed indicator is not working because of ice/tape/bugs/malfunction is he allowed to just give up and throw the airplane into the ground? He has a sudden engine failure, follows the drill but forgets to feather the prop should he just sit there and allow the airplane to roll itself up into a ball? Even distractions in flight have caused the pilot and his passengers to die. All these things have happened and hundreds of people have died as a result, often with professional pilots flying the aircraft.
If a pilot gets ice on the tailplane and experiences tailplane stalling should he think "I have not been trained to handle this so I just give up?" If a pilot finds that after lift off his airspeed indicator is not working because of ice/tape/bugs/malfunction is he allowed to just give up and throw the airplane into the ground? He has a sudden engine failure, follows the drill but forgets to feather the prop should he just sit there and allow the airplane to roll itself up into a ball? Even distractions in flight have caused the pilot and his passengers to die. All these things have happened and hundreds of people have died as a result, often with professional pilots flying the aircraft.
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Thats hardly giving up, is it ?
Last edited by Fly Aiprt; 29th May 2019 at 16:12. Reason: Typo
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No, but what they should have been doing at that stage was returning to land after completing the procedure that we all learned from the Lion air crash.
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Secondly it might have been what they should have been doing per procedure, but the only other crew to experience MCAS didn't turn back - and they (and their pax) are alive. Coincidence again, or causal?
Thirdly no 737 pilot should have been learning any procedure from Lion Air crash - no new procedures were created.
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According to the report they were turning back when the final LOC happened (and they certainly returned to land...). Lion air were also returning when they crashed. Coincidence? - probably, but I would want to look at the possibility that turning contributed in some way to final LOC.
Could it be that pilot input to change heading contributed to the AP disengagement ? Those events occurred around 05:39:48...
It is not important why the stab system failed. It could have been a myriad of things. All a pilot has to do is fly the airplane. It happens many times without a problem and we don't even hear about it. Engines fail and pilots do the right thing, they handle icing, mechanicals, recognize subtle incapacitation, low oil pressure, engine failures, prop runaways, incipient stalls, seat belts hanging out of the door, out of balance loading, bird strikes and more and don't decide to kill themselves and their passengers. That is what we expect and deserve from a professional pilot.
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If they fail, we have to be able to see that as not only a warning to build our airplanes better (add stall warning, anti ice equipment, better passenger restraint, fire bottles etc) but also recognize when pilot training has failed. And do better. But if we deny the pilot element and do nothing we better get ready for the body bag companies to increase their stock prices.
1. The JT crew didn't have any advice on the matter.
2. The ET crew had limited guidance provided by the OEM in his all operators notices.
3. The OEM notice didm't reinforce the issue of loss of trim capability on selecting stab trim cutout.
4. The ET crew followed initially the guidance material, and then for reasons to be investigated elected to return the stab trim operation, which then went pear shaped.
One can assume that this crew was trying their best with the information and training they had, and for some reason elected to return the stab to normal operation. I suspect we are going to find that the stab being defeated by airloads on the B737 is substantially worse on the Max/NG than any other type, and that it could even be marginal within the existing out of trim standard which is a lower level of mis-trim than the MCAS can and did result in.
It has taken some months of discussions to indicate the problems of airloads on the mis-trimmed stabiliser, and Max experience of that condition comes down to a single deceased crew, ET302, and possibly the OEM's TPs over the last 3 months. The simulator is stated to not reflect the event correctly, which leaves the MCAB and flight test as the only place that it is likely to evaluate how severe the mis-trim air loads problem really is.
Something caused the guys to reset the cutouts... and I would suggest that it is a mathematical certainty that no one on this forum other than an OEM TP has actual experience with the Max8 mis-trim airloads, so comments on competency, not fighting etc would seem to be unwarranted.
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Except they really didn’t. The closest they came was the FO shouting “Stab trim cutout”, and then someone flipped the cutout switches before there was any attempt to neutralize the trim. It is not even clear from the CVR transcript that they were executing any “guidance material.” That would have required actually calling for a checklist.
This is about the same level of competence as someone shouting “Fire” immediately followed by someone shutting down engines and firing off halon bottles without any attempt to identify, confirm, and execute the checklist in the way it was designed. There is a reason that we have very specific instructions on how to accomplish non-normal checklists. It has been proven many times in the past that rushing through an emergency procedure can have a bad outcome, and this case was no different.
This is about the same level of competence as someone shouting “Fire” immediately followed by someone shutting down engines and firing off halon bottles without any attempt to identify, confirm, and execute the checklist in the way it was designed. There is a reason that we have very specific instructions on how to accomplish non-normal checklists. It has been proven many times in the past that rushing through an emergency procedure can have a bad outcome, and this case was no different.
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Except they really didn’t. The closest they came was the FO shouting “Stab trim cutout”, and then someone flipped the cutout switches before there was any attempt to neutralize the trim. It is not even clear from the CVR transcript that they were executing any “guidance material.”
Except they really didn’t. The closest they came was the FO shouting “Stab trim cutout”, and then someone flipped the cutout switches before there was any attempt to neutralize the trim. It is not even clear from the CVR transcript that they were executing any “guidance material.” That would have required actually calling for a checklist.
This is about the same level of competence as someone shouting “Fire” immediately followed by someone shutting down engines and firing off halon bottles without any attempt to identify, confirm, and execute the checklist in the way it was designed. There is a reason that we have very specific instructions on how to accomplish non-normal checklists. It has been proven many times in the past that rushing through an emergency procedure can have a bad outcome, and this case was no different.
This is about the same level of competence as someone shouting “Fire” immediately followed by someone shutting down engines and firing off halon bottles without any attempt to identify, confirm, and execute the checklist in the way it was designed. There is a reason that we have very specific instructions on how to accomplish non-normal checklists. It has been proven many times in the past that rushing through an emergency procedure can have a bad outcome, and this case was no different.
Yoko, the OEB doesn't provide a checklist, it provides guidance material and procedures, which in this case had no information that would assist a crew faced with a manual trim overcome by airloads at low altitude in the AND case.
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page 11
You mean OEM as in “Boeing”? I thought you were referring to the runaway stab procedure, which is published and was discussed in the post-Lion Air AD. If you mean that there was no reference to the problems of manual trimming from a large out of trim state, then yes, that has not been in the 737 manuals for a very long time, and it ought to be restored. That being said the ET crew could have avoided the large out of trim state through the use of the pilot’s yoke trim switch. It was working, but it was not used effectively. If you wish to see what effective use looks like, look at the first Lion Air flight and the first seven minutes of the second Lion Air accident flight before the Captain transferred aircraft control to the First Officer.
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https://flightsafety.org/wp-content/...-AVJ.pdf#page9
page 11
You mean OEM as in “Boeing”? I thought you were referring to the runaway stab procedure, which is published and was discussed in the post-Lion Air AD. If you mean that there was no reference to the problems of manual trimming from a large out of trim state, then yes, that has not been in the 737 manuals for a very long time, and it ought to be restored. That being said the ET crew could have avoided the large out of trim state through the use of the pilot’s yoke trim switch. It was working, but it was not used effectively. If you wish to see what effective use looks like, look at the first Lion Air flight and the first seven minutes of the second Lion Air accident flight before the Captain transferred aircraft control to the First Officer.
page 11
You mean OEM as in “Boeing”? I thought you were referring to the runaway stab procedure, which is published and was discussed in the post-Lion Air AD. If you mean that there was no reference to the problems of manual trimming from a large out of trim state, then yes, that has not been in the 737 manuals for a very long time, and it ought to be restored. That being said the ET crew could have avoided the large out of trim state through the use of the pilot’s yoke trim switch. It was working, but it was not used effectively. If you wish to see what effective use looks like, look at the first Lion Air flight and the first seven minutes of the second Lion Air accident flight before the Captain transferred aircraft control to the First Officer.
At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and FirstOfficer confirmed stab trim cut-out.
Also note that the 'lion air emergency AD" casually mentions the possible problems with air loads in a note section and does not at all stress using pilot trim switches, which would be equally catastrophic if a 'stuck relay' trim run-away was happening...
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Murphy,
Care to enlighten us as to how many 737 checklists have the pilots use the stab trim cutout switches? And how many steps come before that particular action was supposed to be taken? I agree it was not random, and it may be a bit strong to say “panicked” (your word, BTW, not mine), but it was hasty, ill-considered, and ultimately fatal.
Care to enlighten us as to how many 737 checklists have the pilots use the stab trim cutout switches? And how many steps come before that particular action was supposed to be taken? I agree it was not random, and it may be a bit strong to say “panicked” (your word, BTW, not mine), but it was hasty, ill-considered, and ultimately fatal.
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I would submit that the Ethiopian MOT has a very strong bias against publishing anything that would call into question pilot training, certification, and/or competency issues. Thus, any statements issued by the MOT regarding flight crew actions or competency should be viewed with the same degree of skepticism as we give toward statements by Boeing regarding the safety of the 737 MAX design and statements by the FAA regarding the integrity of the certification process.
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As MurphyWasRight mentioned, the FO called out Cutout Switches, and the Captain agreed.
As a comparison, carefully reading a final report from the NTSB could help better understand what a CVR transcript is.
It would also show how investigators carefully search for any information before concluding as to the probable causes of the mishap and refrain of jumping to conclusions or putting blame on anyone.
Last edited by Fly Aiprt; 30th May 2019 at 07:49. Reason: Typo
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I just re-read that link and noticed something interesting to a data person, what does this mean? To me this indicates that the fan speed target was recorded as NAN (not a number) or some other error signal, and I can't figure out how that could be related to unreliable airspeed.
The N1 target indicated non data pattern 220 seconds before the end of recording.
Yoko.
One or several of the experienced 737 pilots that have posted along the line of pilots fault.
Said first thing is to hit the cut out switches - not trim to a neutral, them kill the switches.
These comments were made before the simulator deficiencies were made. So these pilots also could have hit the switches and found that it was too far out of trim, for manual trim wheel operation. So what to do now when you expect the wheel to move but it will not move?
You need to maintain power and pitch and your out of trim - with a frozen trim wheel and a few distractions going on. Do you start the "Yo-Yo" procedure at what is a low altitude or turn the switches on to try the trim?
Question - If the column trim switch is held trim up THEN the cut outs are turned back on, would it trim or does the column switch need to be "reset" to neutral then back to nose up?
Why would you turn the cut out trim switches back on, if you were not intending to trim?
One or several of the experienced 737 pilots that have posted along the line of pilots fault.
Said first thing is to hit the cut out switches - not trim to a neutral, them kill the switches.
These comments were made before the simulator deficiencies were made. So these pilots also could have hit the switches and found that it was too far out of trim, for manual trim wheel operation. So what to do now when you expect the wheel to move but it will not move?
You need to maintain power and pitch and your out of trim - with a frozen trim wheel and a few distractions going on. Do you start the "Yo-Yo" procedure at what is a low altitude or turn the switches on to try the trim?
Question - If the column trim switch is held trim up THEN the cut outs are turned back on, would it trim or does the column switch need to be "reset" to neutral then back to nose up?
Why would you turn the cut out trim switches back on, if you were not intending to trim?
Psychophysiological entity
This got split from Water pilot's post # 179 Which was:
Way back I'd noticed that though of a much shorter duration, the Fuel Flow of the JK flight was the highest it had been since take-off - just before the sudden climb.
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I just re-read that link and noticed something interesting to a data person, what does this mean? To me this indicates that the fan speed target was recorded as NAN (not a number) or some other error signal, and I can't figure out how that could be related to unreliable airspeed.
Quote:
The N1 target indicated non data pattern 220 seconds before the end of recording.
The N1 target indicated non data pattern 220 seconds before the end of recording.
Way back I'd noticed that though of a much shorter duration, the Fuel Flow of the JK flight was the highest it had been since take-off - just before the sudden climb.
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Last edited by Loose rivets; 30th May 2019 at 14:41.
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The above question was raised back on 05 May in another thread about the Ethiopian crash. That thread has since been closed, because it had accumulated a bazillion or so posts.
Cheers,
Grog
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Originally Posted by Bend alot;[url=tel:10482520
10482520]Yoko.
One or several of the experienced 737 pilots that have posted along the line of pilots fault.
Said first thing is to hit the cut out switches - not trim to a neutral, them kill the switches.
One or several of the experienced 737 pilots that have posted along the line of pilots fault.
Said first thing is to hit the cut out switches - not trim to a neutral, them kill the switches.
I don’t really see the crew errors as being a case of the pilots personally being at fault, but rather continued evidence that airlines around the world (including, sadly, mine) continue to underinvest in their pilots, by some combination of accepting ridiculously low experience (i.e. the ET302 First Officer) and/or minimal training that is heavy on managing the automation and checking off boxes in the sim and light on managing the aircraft (to include proficiency in hand-flying) and preparation for unusual, out of the box situations.
As far as use of the trim cutout switches, we have to assume the ET crew was either following an established procedure or not. If they were attempting to accomplish the runaway stab procedure (the only one that I know of that uses the cutout switches), then they did it incorrectly leaving the aircraft in a grossly out of trim condition. If they were not following a published procedure and merely grasping at straws, then they were grasping at the wrong straw. The immediate remedy to the MCAS inputs was the yoke trim switch, not the trim cutout switch. Once the trim had been neutralized (or at least close), only then would it have been appropriate to disable all electric trim.
These comments were made before the simulator deficiencies were made. So these pilots also could have hit the switches and found that it was too far out of trim, for manual trim wheel operation. So what to do now when you expect the wheel to move but it will not move?
You need to maintain power and pitch and your out of trim - with a frozen trim wheel and a few distractions going on. Do you start the "Yo-Yo" procedure at what is a low altitude or turn the switches on to try the trim?
Question - If the column trim switch is held trim up THEN the cut outs are turned back on, would it trim or does the column switch need to be "reset" to neutral then back to nose up?
Why would you turn the cut out trim switches back on, if you were not intending to trim?
Why would you turn the cut out trim switches back on, if you were not intending to trim?