Nepal Plane Crash
(PAX). From my position of layperson ignorance, I find it a bit odd that the 'pilot monitoring' gets to move controls. Is the 'pilot flying' meant to monitor the ' pilot monitoring' for these actions ? In this case, from what I can see, the initial pf didn't do much in the way of monitoring either after control was handed over to the previous pm.
Is the task of landing so onerous that the pf can't manipulate flaps and gear under the watchful gaze of the pm ? Genuinely puzzled .
Is the task of landing so onerous that the pf can't manipulate flaps and gear under the watchful gaze of the pm ? Genuinely puzzled .
In general the pilot flying manipulates the primary flight controls and power levers. As that will take the most attention the pilot monitoring 'monitors' flight path as well as operates ancillary controls and radios etc when called for by the PF. This also means any call for flaps, gear etc can be checked by both pilots as both pilots are involved in the operation. If you give the PM too little to do they tend to get distracted as well.
This is where a good disciplined approach to operating the systems should be built by the airline check and training department. Pushing a methodical approach to something as simple as setting flap, eg, you can place your hand on the flap lever when called for, visually check you have the correct lever, check the speed is below the limit for that setting, move the lever incrementally to the desired setting (this reduces the chance of flap asymmetry). Immediately check the flap indicator is moving in the correct direction, and in unison, keep your hand on the lever until the desired setting is indicated as called for.
My take on what possibly happened is in a training environment the trainer will be watching the flight path and alignment with the runway. He has skipped some final crosschecks whilst fixated on the runway and approach path the flying pilot is following. As a result grabbed the wrong lever, never visually checked, never confirmed settings. The lack of power from both engines suddenly would startle any pilot, especially for no apparent reason. Sully saw the geese coming, so the recognition of loss of power was fairly quick and then they kicked into a response to it. The PF especially would not really expect both engines to suddenly not produce any torque, but still indicating running status, I can understand why she would have been very confused, and they just didn't have excess time to go through a methodical check of why, with the ground approaching fast.
My take on what possibly happened is in a training environment the trainer will be watching the flight path and alignment with the runway. He has skipped some final crosschecks whilst fixated on the runway and approach path the flying pilot is following. As a result grabbed the wrong lever, never visually checked, never confirmed settings. The lack of power from both engines suddenly would startle any pilot, especially for no apparent reason. Sully saw the geese coming, so the recognition of loss of power was fairly quick and then they kicked into a response to it. The PF especially would not really expect both engines to suddenly not produce any torque, but still indicating running status, I can understand why she would have been very confused, and they just didn't have excess time to go through a methodical check of why, with the ground approaching fast.
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Little war story: On one of my first fights in a small aircraft (just before I began my own training), at the completion of the 150nm cross-country we ended up a bit high on final.
The newly-minted (and thus very current in training) pilot in the left seat reached over to pull back the C152's throttle and reduce power. Which he did very successfully - the engine and prop stopped altogether. He had grabbed and pulled the MIXTURE knob all the way back. Despite it being 1) screaming RED in color, and 2) having a push-button lock to prevent inadvertent movement.
At which point the excess altitude became very useful - as we glided to a perfect touchdown on the runway.
Pilots at all levels of experience can do (and have done) the darndest things. Which is why, whenever I see an argument that "No pilot would ever......," I carefully fold it four ways and deposit it in the trash-basket.
Had we crashed, the investigators would no doubt have found the mixture lever at cutoff, just as the investigators here found the condition levers at feather.
There may be two condition levers - but they are intentionally set very close together (cheek by jowl), because they are usually moved as one to maintain symmetrical engine conditions.
The newly-minted (and thus very current in training) pilot in the left seat reached over to pull back the C152's throttle and reduce power. Which he did very successfully - the engine and prop stopped altogether. He had grabbed and pulled the MIXTURE knob all the way back. Despite it being 1) screaming RED in color, and 2) having a push-button lock to prevent inadvertent movement.
At which point the excess altitude became very useful - as we glided to a perfect touchdown on the runway.
Pilots at all levels of experience can do (and have done) the darndest things. Which is why, whenever I see an argument that "No pilot would ever......," I carefully fold it four ways and deposit it in the trash-basket.
Had we crashed, the investigators would no doubt have found the mixture lever at cutoff, just as the investigators here found the condition levers at feather.
There may be two condition levers - but they are intentionally set very close together (cheek by jowl), because they are usually moved as one to maintain symmetrical engine conditions.
He asked me if that had ever happened before to which I replied, no. Would it stop me doing it again ? I used to think no but as I gained experience, I realised that wasn't necessarily the case....
Thank you. Looks like the call for flaps didn't get monitored too well here. In this case there seems to be an odd isolation/disconnect between them. Not sure how the pf recognised no thrust but did nothing about it. As a non pilot it is a surprise how quickly a situation can deteriorate to unrecoverable. Thanks again.
The PF heard the engines making power, just as they had been.
There would have been terrible confusion when the speed loss was noted and adding more power didn't change the speed, but I expect it was too late to scan all the instruments before finally getting to the prop feather levers.
While one might think that would be the first place to look, what would have been the action that would have changed their position that the PF would have based that scan on? At the same time the PF had no doubt been confused by the requirement to ask for the flap setting a second time as that trim change (or lack of it after the first request) would have been noticeable. The PF depended on the experienced PM to do what was agreed upon and not make a horrible screw-up.
As I mentioned earlier - those levers should have a related voice recording overriding every other sound the cockpit can make with "FEATHER 1 FEATHER 2" because the results of unexpected feathering are devastating.
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Yes but according to grizzled who posted this memo , it was leaked on Jan 30th , and we know now that the CVR/FDR were not read in Nepal and well after this date. reading it again , especially the first line of it : The existing approach procedure for domestic air operators was critically reviewed ,,etc.. and continues saying : all airplanes in Nepal oerating in STOL airfields , etc..
On second toughts it looks like this satement was probably in pipeline before the accident and the Team used the accident to leak it , to show they were on top of things, but I doubbt it was written, at least not in its totality, especially for this Yeti ATR accident .But maybe it was , we;ll see when the final is out.
@Lookleft
Incredible seen the difference in shape, and operation. . I must revise my human factors list of ergonomics nightmares.stories ...
@Parkfell :
indeed and we could add Asiana 777 in SFO which also stalled with 3. But to be fair on many other incidents a 3rd or even 4th ( QF32 ) saved the day.
On second toughts it looks like this satement was probably in pipeline before the accident and the Team used the accident to leak it , to show they were on top of things, but I doubbt it was written, at least not in its totality, especially for this Yeti ATR accident .But maybe it was , we;ll see when the final is out.
@Lookleft
Incredible seen the difference in shape, and operation. . I must revise my human factors list of ergonomics nightmares.stories ...
@Parkfell :
indeed and we could add Asiana 777 in SFO which also stalled with 3. But to be fair on many other incidents a 3rd or even 4th ( QF32 ) saved the day.
I applied aviation principles to an IT environment a few years ago and once we had created a safe environment where team members felt comfortable to talk, we were all amazed at what came up at our 1st near miss meeting! This was all prompted by someone accidentally shutting down a production server instead of a test one. Out of 20 people in the meeting, 75% said they had nearly done the same thing! We also looked at factors at play when these near misses took place and the usual suspects were there but for a significant minority, we could not identify the potential 'why'...
Simply writing it off as stupidly, laziness, mind not on the job, unprofessional behaviour is, well stupidity IMHO.
Last edited by Compton3fox; 9th Mar 2023 at 01:49.
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As I said before All FCU/MCP actions and movement of any control lever like flaps, gear, parking brake or anything else like the condition levers are not to be done from muscle memory or subconsciously. These are identify and do actions and as long as that's not done no ergonomics or colour schemes will work. More the experience or familiarity with the cockpit more you are likely to fall prey to it. Gear is shaped with wheel, flap looks like a wing they are not close by move differently but people have retracted wrong control. Keep those hands in the lap till something is ordered then think before you reach for it. There's simply no other way.
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They were descending. How much thrust would they need? The PM should have been noticing the drop in air speed.
The PF heard the engines making power, just as they had been.
There would have been terrible confusion when the speed loss was noted and adding more power didn't change the speed, but I expect it was too late to scan all the instruments before finally getting to the prop feather levers.
While one might think that would be the first place to look, what would have been the action that would have changed their position that the PF would have based that scan on? At the same time the PF had no doubt been confused by the requirement to ask for the flap setting a second time as that trim change (or lack of it after the first request) would have been noticeable. The PF depended on the experienced PM to do what was agreed upon and not make a horrible screw-up.
As I mentioned earlier - those levers should have a related voice recording overriding every other sound the cockpit can make with "FEATHER 1 FEATHER 2" because the results of unexpected feathering are devastating.
The PF heard the engines making power, just as they had been.
There would have been terrible confusion when the speed loss was noted and adding more power didn't change the speed, but I expect it was too late to scan all the instruments before finally getting to the prop feather levers.
While one might think that would be the first place to look, what would have been the action that would have changed their position that the PF would have based that scan on? At the same time the PF had no doubt been confused by the requirement to ask for the flap setting a second time as that trim change (or lack of it after the first request) would have been noticeable. The PF depended on the experienced PM to do what was agreed upon and not make a horrible screw-up.
As I mentioned earlier - those levers should have a related voice recording overriding every other sound the cockpit can make with "FEATHER 1 FEATHER 2" because the results of unexpected feathering are devastating.
The pilot flying is not expecting to hear "FEATHER" at 100 dBa. This is not what one would hear when the intended flaps are actuated and they would have, at that time, lost very little airspeed and both would focus on why there was a FEATHER announcement - the PM would still have his hand on the lever which would be a huge hint.
There didn't seem to be any stress on either pilot when the error was made - the PM was seemingly distracted, not stressed; the PM was simply not paying attention**. The flight was smooth enough, the day was nice, the weather was clear, the runway was in sight. The confusion and stress came later when they noticed the airspeed had dropped.
The problem with physical interlocks is they can prevent motion that is desired. It's also far harder to get the logic right versus the relative simplicity of adding a couple of relays, switches, and a pre-recorded message box.
**OK - I wasn't there, but wouldn't it have been acknowledged by the initial investigation if alarms and alerts had been going off when the PF asked for flaps and a terrified PM just grabbed controls at random in a panic?
There didn't seem to be any stress on either pilot when the error was made - the PM was seemingly distracted, not stressed; the PM was simply not paying attention**. The flight was smooth enough, the day was nice, the weather was clear, the runway was in sight. The confusion and stress came later when they noticed the airspeed had dropped.
The problem with physical interlocks is they can prevent motion that is desired. It's also far harder to get the logic right versus the relative simplicity of adding a couple of relays, switches, and a pre-recorded message box.
**OK - I wasn't there, but wouldn't it have been acknowledged by the initial investigation if alarms and alerts had been going off when the PF asked for flaps and a terrified PM just grabbed controls at random in a panic?
There didn't seem to be any stress on either pilot when the error was made - the PM was seemingly distracted, not stressed; the PM was simply not paying attention**. The flight was smooth enough, the day was nice, the weather was clear, the runway was in sight. The confusion and stress came later when they noticed the airspeed had dropped.
We all make mistakes, I just hope mine are limited to simple easy to fix things, in understanding that we all can err, we can then move forward and build up our own defenses against them.
As for more mechanical locks, as said above there are then brings in issues when you really want to feather the props expeditiously. You don't want the asinine computer frustration of everything confirmed with "are you sure y/n" "are you really sure y/n" "and one last time are you really, really absolutely sure you don't want toast? y/n".
I think more bells and whistles would have helped here, the idea of aural feather alerts is a good one IMO. Is it possible in this case as well, if it was some weirdly ridiculous mechanical problem, that if they were alerted earlier to the feathered props that they could have altered flightpath to land on one of the runways nearby? We still don't know why the props feathered exactly, it does look most likely the PM did it, but there is a lot more data to be released before its certain. Then there is also the remote possibility the PM did it intentionally for whatever reason.... It may be we never really know why.
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We don't have enough information for that call just yet, that is to determine what the workload was like. Circuits, especially the latter part of downwind, base and final is very high workload in a large aircraft, the PF is very engaged with positioning, vertical profile, speed and configuration. In this case the aircraft was at very high weight, we known that as it was full, so the speeds would all be increased and the PM in a training environment would be keenly watching everything the PF does. I would say the PM was at high workload to give them the benefit of the doubt, add in the PF being off profile, wide or close, a bit fast or slow, vertical speed not to the PMs liking but within the acceptable range and so on... then add the PMs poor cross cockpit visibility of the turn to final so straining to see alignment you might see an urge then to keep the eyes on other things than something hes done a thousand times before like extend the flap.
We all make mistakes, I just hope mine are limited to simple easy to fix things, in understanding that we all can err, we can then move forward and build up our own defenses against them.
As for more mechanical locks, as said above there are then brings in issues when you really want to feather the props expeditiously. You don't want the asinine computer frustration of everything confirmed with "are you sure y/n" "are you really sure y/n" "and one last time are you really, really absolutely sure you don't want toast? y/n".
I think more bells and whistles would have helped here, the idea of aural feather alerts is a good one IMO. Is it possible in this case as well, if it was some weirdly ridiculous mechanical problem, that if they were alerted earlier to the feathered props that they could have altered flightpath to land on one of the runways nearby? We still don't know why the props feathered exactly, it does look most likely the PM did it, but there is a lot more data to be released before its certain. Then there is also the remote possibility the PM did it intentionally for whatever reason.... It may be we never really know why.
We all make mistakes, I just hope mine are limited to simple easy to fix things, in understanding that we all can err, we can then move forward and build up our own defenses against them.
As for more mechanical locks, as said above there are then brings in issues when you really want to feather the props expeditiously. You don't want the asinine computer frustration of everything confirmed with "are you sure y/n" "are you really sure y/n" "and one last time are you really, really absolutely sure you don't want toast? y/n".
I think more bells and whistles would have helped here, the idea of aural feather alerts is a good one IMO. Is it possible in this case as well, if it was some weirdly ridiculous mechanical problem, that if they were alerted earlier to the feathered props that they could have altered flightpath to land on one of the runways nearby? We still don't know why the props feathered exactly, it does look most likely the PM did it, but there is a lot more data to be released before its certain. Then there is also the remote possibility the PM did it intentionally for whatever reason.... It may be we never really know why.
The counter to all this is, has this ever happened before? And how likely is it to happen again vs. the potential other things that could go wrong with such a change.
Last edited by Compton3fox; 10th Mar 2023 at 03:20.
My concern with more aural callouts is that the brain may simply ignore them or hear what it expects to hear in what we suspect was a high workload phase. Good points made about my suggested protection for simultaneously feather of 1 and 2 in-flight. You would be able to feather 1 by one but not at the same time without doing something different to the normal process for feathering just before engine shutdown. So if you try to pull the condition levers when you meant to pull the flaps, chances are, you will use the process you normally use and you will not be able to move the levers. This would then prompt you to look down and see what was preventing them from moving which would show you your error. The process for a simultaneous airborne feather would be very rarely used so unlikely to be done subconsciously or via muscle memory. The risk is that if you did need to do it, would you remember how in the heat of the moment?
The counter to all this is, has this ever happened before? And how likely is it to happen again vs. the potential other things that could go wrong with such a change.
The counter to all this is, has this ever happened before? And how likely is it to happen again vs. the potential other things that could go wrong with such a change.
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If you add a mechanism which under some circumstances prevents a propeller being feathered then you have to factor in the risk that a failure of that mechanism prevents feathering when you need it. Adding complexity generally has a downside that needs to be considered.
has this ever happened before?
While the initial cause was different, the information differential was there. Interlocks only deal with initial cause; what needs to be managed is the information differential.
I'd say the Lion Air 737 MAX crash was also an information differential problem - the Captain had repeatedly completely reset the trim condition of the plane after each MCAS increment, but did not convey that information to the First Officer. The First Office allowed 50-90 pounds of pitch force to accumulate on the wheel but did not inform the Captain this was happening. AF447 crashed because one of the pilots was pulling nose up and holding a stall because, as near as I can tell, he had believed that an Airbus could never stall; this was an information differential with the other pilot who was forcing the nose down. Neither communicated to the other and the Airbus computers did not interrupt that silence.
I agree with you that when adding complexity, you need to consider the possible negatives. However I didn't say you should not allow feather when the AC is airborne, just that there should be a different mechanism to do so and only when both CLs are pulled at same time.
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On reflection, i agree. Its very rare, if at all this has happened in the past.
Almost all of the controls in an aircraft can have fatal consequences if moved incorrectly. To put an oral announcement on each of them would result in a continuous series of alarms going off.
On a previous post by 'Discorde'. The engine numbering scheme could also have problems..
Should we shut both engines down..?
No, just shut down One..
On a previous post by 'Discorde'. The engine numbering scheme could also have problems..
Should we shut both engines down..?
No, just shut down One..
Almost all of the controls in an aircraft can have fatal consequences if moved incorrectly. To put an oral announcement on each of them would result in a continuous series of alarms going off.
On a previous post by 'Discorde'. The engine numbering scheme could also have problems..
Should we shut both engines down..?
No, just shut down One..
On a previous post by 'Discorde'. The engine numbering scheme could also have problems..
Should we shut both engines down..?
No, just shut down One..
Should we shut both engines down..?
No, just shut down Number One..
Train for stupidity
We started with thorough training for mechanical failures. Later we added drills for incapacitation and windshear events.
But when something happens outside the curriculum (dropped checklist items are generally not covered, but bite hard), the crew may not catch on in time or improvise without success. I've witnessed glider writeoffs and a fatality where improvisation failed when the crew was faced with a situation outside the curriculum.
For one example, improperly latched side opening canopies are easily handled with a bit of rudder, but all too often pilots screw up and kill themselves or the tow pilot, or write off the glider. Common in these cases is the impulse to save a $6,000 canopy. Gliders with rear opening canopies do much better because a mislatched canopy is immediately lost and the pilot keeps his attention on flying the glider.
There are many more ways to screw up in a transport aircraft and it might help to train how to recognize and manage dropped checklist items or mishandled controls.
Errare humanum est.
But when something happens outside the curriculum (dropped checklist items are generally not covered, but bite hard), the crew may not catch on in time or improvise without success. I've witnessed glider writeoffs and a fatality where improvisation failed when the crew was faced with a situation outside the curriculum.
For one example, improperly latched side opening canopies are easily handled with a bit of rudder, but all too often pilots screw up and kill themselves or the tow pilot, or write off the glider. Common in these cases is the impulse to save a $6,000 canopy. Gliders with rear opening canopies do much better because a mislatched canopy is immediately lost and the pilot keeps his attention on flying the glider.
There are many more ways to screw up in a transport aircraft and it might help to train how to recognize and manage dropped checklist items or mishandled controls.
Errare humanum est.