July 09, 2025, 18:40:00 GMT
permalink Post: 11918572
Theory alert : If you don\x92t have, or delete the cruise altitude in the FMC the aircraft will command a level off at 400ft, with the thrust levers reducing thrust significantly (I\x92ve seen it in the sim and happened at least once for real to my operator). It\x92s easy to do when loading the descent winds if you hit the wrong button. Could this have been confused with a loss of thrust?
And I would say the cut off switches do make a fairly unique click when being moved - I can hear it in my head as I write this!
And I would say the cut off switches do make a fairly unique click when being moved - I can hear it in my head as I write this!
July 09, 2025, 19:05:00 GMT
permalink Post: 11918581
Edit: And here it is:
July 09, 2025, 19:23:00 GMT
permalink Post: 11918592
Muscle memory is a strange and (usually) wonderous thing. It allows us as humans to perform amazing things without actually thinking about what we are doing. Professional Athletes have perfected this to a high art, but the rest of us do things using muscle memory on a regular basis. Back when I was still racing, I happened to look down at my hands on the steering wheel in fast, bumpy corner, and I was simply amazed at the large, rapid steering inputs that I was making to compensate for the bumps - with absolutely zero conscious thought. Muscle memory at its best.
However, it can also bite us. The Delta dual engine shutdown during takeoff from LA (referenced way back when in the 1st accident thread) was caused by muscle memory - the pilot reached down to set the EEC switches (located near the fuel On-Off switches) but muscle memory caused him to do something else - set both fuel switches to OFF. Fortunately, he quickly recognized his error, placing the switches back to RUN and the engines recovered in time to prevent a water landing (barely).
It is conceivable that a pilot - reaching down to the center console to adjust something unrelated - could have muscle memory cause him to turn the fuel off to both engines. While all new engines are tested for "Quick Windmill Relight" - i.e. the fuel switch is set to CUTOFF with the engine at high power - and the engine must recover and produce thrust withing a specified time (memory says 60 or 90 seconds) - it takes a finite amount of time for the engines to recover (spool down after a power cut at high power is incredibly fast - plus moving the switch to CUTOFF causes a FADEC reset, which means it won't do anything for ~ 1 second). Doing that at a couple hundred feet and the chance that an engine will recover and start producing thrust before ground impact is pretty much zero
However, it can also bite us. The Delta dual engine shutdown during takeoff from LA (referenced way back when in the 1st accident thread) was caused by muscle memory - the pilot reached down to set the EEC switches (located near the fuel On-Off switches) but muscle memory caused him to do something else - set both fuel switches to OFF. Fortunately, he quickly recognized his error, placing the switches back to RUN and the engines recovered in time to prevent a water landing (barely).
It is conceivable that a pilot - reaching down to the center console to adjust something unrelated - could have muscle memory cause him to turn the fuel off to both engines. While all new engines are tested for "Quick Windmill Relight" - i.e. the fuel switch is set to CUTOFF with the engine at high power - and the engine must recover and produce thrust withing a specified time (memory says 60 or 90 seconds) - it takes a finite amount of time for the engines to recover (spool down after a power cut at high power is incredibly fast - plus moving the switch to CUTOFF causes a FADEC reset, which means it won't do anything for ~ 1 second). Doing that at a couple hundred feet and the chance that an engine will recover and start producing thrust before ground impact is pretty much zero
It's ironic that cognitive science arguably started with 'The Cambridge Cockpit'; an attempt to make sense of, and mitigate, pilots doing this sort of thing when tired, stressed and so on. This kick started an ergonomics revolution which appears to have come full circle. Now we have cognitive science offering Bayesian accounts of neural function that might explain how innocent but unfortunate priming of 'muscle memory' when practicing for emergencies could, almost predictably, lead to this sort of complex, protection overriding, error.
As non consciously executing a complex, well practiced, but unintended, action is a fairly common experience in less critical situations, I'm surprised that there isn't already a more effective ergonomic fix than the safety switches fitted.
Last edited by Subsy; 9th July 2025 at 21:58 .
July 09, 2025, 21:34:00 GMT
permalink Post: 11918651
A bit of a pedantic point, but the locking lever in the photo above is not the right action for the fuel cut off switches on the 787. The switch above has two locked positions and a biased further position. You could say ON-OFF-BIASSED. There are some photos earlier in the thread (assuming they are still there) of the correct Honeywell switch and its gate.
Edit: And here it is:
Edit: And here it is:
For those unfamiliar with cockpit controls in general, I\x92ll leave my \x93schematic\x94 image to show the principle of \x93lift-and-move\x94 the toggle vice just pushing the toggle in a desired direction.
Cheers,
PJ2
Last edited by PJ2; 9th July 2025 at 21:45 . Reason: for context
July 09, 2025, 22:25:00 GMT
permalink Post: 11918671
July 8 (Reuters) - A preliminary report into the deadly crash of an Air India jetliner in June is expected to be released by Friday, three sources with knowledge of the matter said, with one adding
the probe had narrowed its focus to the movement of the plane's fuel control switches.
But this is starting to devolve into a hamster wheel again.
Last edited by Chernobyl; 10th July 2025 at 04:32 .
July 09, 2025, 23:20:00 GMT
permalink Post: 11918695
There has been discussion recently about a procedure that involves moving the fuel switches to CUTOFF and then back to RUN following a dual engine failure.
Attached is an image of a page from the Air India 787 Training Manual that discusses this procedure.
I am submitting this without comment or opinion.
Attached is an image of a page from the Air India 787 Training Manual that discusses this procedure.
I am submitting this without comment or opinion.
July 10, 2025, 00:08:00 GMT
permalink Post: 11918713
As a 787 operator I can observe a couple of things......
Deliberately cycling the Engine Cutoff switches just after rotate, in response to a dual power loss is inconceivable. You are way too low and slow for it to have any effect and your attention is better devoted to aiming for the flattest area ahead to crash into. Commencing the Dual Eng Fail/Stall checklist memory items is conditional upon both engines being at sub-idle and the aircraft being within the in-flight relight envelope. Neither of those conditions existed.
Deliberately cycling the Engine Cutoff switches just after rotate, in response to a dual power loss is inconceivable. You are way too low and slow for it to have any effect and your attention is better devoted to aiming for the flattest area ahead to crash into. Commencing the Dual Eng Fail/Stall checklist memory items is conditional upon both engines being at sub-idle and the aircraft being within the in-flight relight envelope. Neither of those conditions existed.
July 10, 2025, 00:21:00 GMT
permalink Post: 11918716
Obviously, because it's going to require quick action to catch high RPM. And maybe that's what they tried.
It also seems to be indicating that fuel switch resetting should be attempted if the restart has failed to start the engine?
July 10, 2025, 00:57:00 GMT
permalink Post: 11918722
A
very
cursory review of the FDR data will indicate if the fuel switches were cycled as a response to an engine rundown, or if the engine rundown was in response to the fuel switches being cycled.
July 10, 2025, 01:30:00 GMT
permalink Post: 11918727
I don't have any comment on it other than to note that the manual is not specific to Air India. My B787-9 FCTM is identical as far as I can tell. The actual memory item for dual failure is to reset the fuel switches and start the RAT. It is also conditional on the engines being sub idle as noted by the other poster.
July 10, 2025, 01:41:00 GMT
permalink Post: 11918730
I don't have any comment on it other than to note that the manual is not specific to Air India. My B787-9 FCTM is identical as far as I can tell. The actual memory item for dual failure is to reset the fuel switches and start the RAT. It is also conditional on the engines being sub idle as noted by the other poster.
* (Or to be fair, these guys, this cockpit team were...)
Last edited by MaybeItIs; 10th July 2025 at 01:55 . Reason: grammar (still bad, never mind), a bit better 2nd time
July 10, 2025, 08:26:00 GMT
permalink Post: 11918827
It is not inconceivable to me that a human being who THINKS they've had a dual engine failure at possibly the worst time imaginable (correctly or incorrectly) and has not taken the time to confirm, or take it all in and has immediately launched into memory items. I could certainly foresee one being rather startled by the energy state and the rapidly approaching buildings.
I'm not saying that this happened to this crew but it certainly could happen to someone. People do weird !!!! under high stress. There is an initial "oh !!!!, what's going on" then the training kicks in. Often at super fast rate and the challenge becomes slowing it all down.
The bloody master warning on the Airbus for smoke in the forward Lav used to get me everytime. Was always at night over the ocean too.
I'm not saying that this happened to this crew but it certainly could happen to someone. People do weird !!!! under high stress. There is an initial "oh !!!!, what's going on" then the training kicks in. Often at super fast rate and the challenge becomes slowing it all down.
The bloody master warning on the Airbus for smoke in the forward Lav used to get me everytime. Was always at night over the ocean too.
July 10, 2025, 08:59:00 GMT
permalink Post: 11918849
A couple of points if I may......
I don't see it written in the 787 FCOM but I have always been told that the action of resetting the Engine Cutoff switches in the event of a dual engine failure, is merely backing up what the FADECs have already done. If there is an 'engine event' the FADECs will manage ignition and fuel-flow to restore the thrust that was demanded before the event. If that management has failed then the manual resetting may be more successful. (The same holds true for the RAT, manual selection is merely backing up the auto-deployment).
Any airline pilot will tell you that executing an in-flight relight on a big engine, no matter if it is by electric start, windmilling RPM or cross-bleed assisted, can take between 1 and 3 minutes to restore power. This aircraft was airborne for less that 30 seconds. No pilot in his right mind would prioritise an in-flight relight procedure, in a situation where they had neither the time, the height nor the speed for it to succeed. I have no doubt the crew focussed entirely on pointing the aircraft at the clearest area they could see, to mitigate what would inevitably follow.
I don't see it written in the 787 FCOM but I have always been told that the action of resetting the Engine Cutoff switches in the event of a dual engine failure, is merely backing up what the FADECs have already done. If there is an 'engine event' the FADECs will manage ignition and fuel-flow to restore the thrust that was demanded before the event. If that management has failed then the manual resetting may be more successful. (The same holds true for the RAT, manual selection is merely backing up the auto-deployment).
Any airline pilot will tell you that executing an in-flight relight on a big engine, no matter if it is by electric start, windmilling RPM or cross-bleed assisted, can take between 1 and 3 minutes to restore power. This aircraft was airborne for less that 30 seconds. No pilot in his right mind would prioritise an in-flight relight procedure, in a situation where they had neither the time, the height nor the speed for it to succeed. I have no doubt the crew focussed entirely on pointing the aircraft at the clearest area they could see, to mitigate what would inevitably follow.
July 10, 2025, 09:36:00 GMT
permalink Post: 11918879
[emphasis added]
D Bru : if that were actually the scenario, would they not instead be focusing on why "for some extraordinary reason [they were] confronted with both engines out on lift off", rather than having "narrowed its focus to the movement of the plane's fuel control switches", which would just be a side effect not a root cause?
But this is starting to devolve into a hamster wheel again.
D Bru : if that were actually the scenario, would they not instead be focusing on why "for some extraordinary reason [they were] confronted with both engines out on lift off", rather than having "narrowed its focus to the movement of the plane's fuel control switches", which would just be a side effect not a root cause?
But this is starting to devolve into a hamster wheel again.
Anyway, the other thread is open at the moment, maybe this should be moved there.
July 10, 2025, 09:59:00 GMT
permalink Post: 11918893
Ex 787 pilot here, I can confirm that the excerpt from the FCTM above is correct, and also confirm that the QRH memory items for Dual Engine Fail/Stall are:
Condition: Engine speed for both engines is below idle
Fuel Control Switches (both) \x85 CUTOFF then RUN
RAM AIR TURBINE switch \x85 Push and hold for1 second
Condition: Engine speed for both engines is below idle
Fuel Control Switches (both) \x85 CUTOFF then RUN
RAM AIR TURBINE switch \x85 Push and hold for1 second
July 10, 2025, 11:12:00 GMT
permalink Post: 11918942
The data recorder has all the information most are questioning. They already know if the fuel control switches were selected to cutoff and they know if this happened before or after the loss of thrust. Perhaps the sequence of events will be more clear tomorrow. I can tell you that from aircraft rotation to loss of thrust was a very short time period. Perhaps 8 seconds. I simply won’t believe in that time period the crew were taking any non deliberate actions that would have shut the motors down.
July 10, 2025, 11:14:00 GMT
permalink Post: 11918946
Ex 787 pilot here, I can confirm that the excerpt from the FCTM above is correct, and also confirm that the QRH memory items for Dual Engine Fail/Stall are:
Condition: Engine speed for both engines is below idle
Fuel Control Switches (both) \x85 CUTOFF then RUN
RAM AIR TURBINE switch \x85 Push and hold for1 second
Condition: Engine speed for both engines is below idle
Fuel Control Switches (both) \x85 CUTOFF then RUN
RAM AIR TURBINE switch \x85 Push and hold for1 second
July 10, 2025, 11:42:00 GMT
permalink Post: 11918961
787 pilots, If throttles are NOT at idle, will their respective fuel cut off switches still trigger a shutdown?
The above checklist procedure implies throttle lever angle and cutoff switches are independant for resetting FADECs.
If so, is it time for this convention from the days where throttles and cutoffs were mechanical systems, not resolvers and switches, to end?
Risk vs reward? Requires more coordination between PF and PM in cases where cutoff is not desired by PF- keep throttle/s up, cannot be surprised by a fuel cutoff.
The above checklist procedure implies throttle lever angle and cutoff switches are independant for resetting FADECs.
If so, is it time for this convention from the days where throttles and cutoffs were mechanical systems, not resolvers and switches, to end?
Risk vs reward? Requires more coordination between PF and PM in cases where cutoff is not desired by PF- keep throttle/s up, cannot be surprised by a fuel cutoff.
Last edited by moosepileit; 10th July 2025 at 11:53 .
July 10, 2025, 11:53:00 GMT
permalink Post: 11918969
787 pilots, If throttles are NOT at idle, will their respective fuel cut off switches still trigger a shutdown?
The above checklist procedure implies throttle lever angle and cutoff switches are independant for resetting FADECs.
If so, is it time for this convention from the days where throttles and cutoffs were mechanical systems, not resolvers and switches, to end?
The above checklist procedure implies throttle lever angle and cutoff switches are independant for resetting FADECs.
If so, is it time for this convention from the days where throttles and cutoffs were mechanical systems, not resolvers and switches, to end?
July 10, 2025, 11:58:00 GMT
permalink Post: 11918976
787 pilots, If throttles are NOT at idle, will their respective fuel cut off switches still trigger a shutdown?
The above checklist procedure implies throttle lever angle and cutoff switches are independant for resetting FADECs.
If so, is it time for this convention from the days where throttles and cutoffs were mechanical systems, not resolvers and switches, to end?
Risk vs reward? Requires more coordination between PF and PM in cases where cutoff is not desired by PF- keep throttle/s up, cannot be surprised by a fuel cutoff.
The above checklist procedure implies throttle lever angle and cutoff switches are independant for resetting FADECs.
If so, is it time for this convention from the days where throttles and cutoffs were mechanical systems, not resolvers and switches, to end?
Risk vs reward? Requires more coordination between PF and PM in cases where cutoff is not desired by PF- keep throttle/s up, cannot be surprised by a fuel cutoff.
