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Preliminary report into Air India crash released

bbc.co.uk

31–40 of 924 posts

Re: Preliminary report into Air India crash released

#31

Quote: As we just reported, the report says that according to data from the flight recorder both the fuel control switches, which are normally used to switch the engines on or off when on the ground, were moved from the run to the cutoff position shortly after takeoff. This caused both engines to lose thrust. The preliminary report suggests this is pilot error.

From my (limited) understanding you cannot really switch these off inadvertently as they require a couple of actions in order to be switched off. So it would mean one of the pilots switched these off (and they were a few seconds later switched on again but it was too late). But there was audio, too, and one pilot asked the other "why did you switch these off" and the second one said "I didn't". Was there are third on…

Sounds likely that one of them was sabotaging the flight.

Re: Preliminary report into Air India crash released

#32

> The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. So the fuel supply was cut off intentionally. The swi…

Does the Flight Data Recorder consider the physical position of the fuel switches or does it get the information from some fly-by-wire part that could be buggy? The conversation would suggest that the switches were in CUTOFF position, but there is also a display that summarizes the engine status. There is no conversation that mentions flipping the switch to RUN again. EDIT: Why is there no Cockpit Video Recorder? The…

[deleted]

Re: Preliminary report into Air India crash released

#33
post #22

Earlier quoted context omitted.

You have to pull the switches out (against a spring) to be able to move them over a notch and flip them. Not really something you can just mistake for another switch or bump into by accident. I'd liken it to turning off the ignition by turning the key while driving your car. Possibly something that could happen if you're really fatigued, but requires quite a mental lapse.

Report says the switches went to cutoff one second apart from each other. Can a human do the physical operation on two switches that quickly?

There's a good photo of them here; https://theaircurrent.com/aviation-safety/ai171-investigatio...

You can do them both with one hand.

Re: Preliminary report into Air India crash released

#34
post #4

The India AAIB website ( https://aaib.gov.in/ ) is not responding ... For anyone who read the report, was there information about the age & experience of the pilots?

56 years old, 15638 hours (8596 on this type) and 32 years old, 3403 hours (1128 on this type). Page 11 of the PDF report.

Re: Preliminary report into Air India crash released

#35

> The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. So the fuel supply was cut off intentionally. The swi…

Does the Flight Data Recorder consider the physical position of the fuel switches or does it get the information from some fly-by-wire part that could be buggy? The conversation would suggest that the switches were in CUTOFF position, but there is also a display that summarizes the engine status. There is no conversation that mentions flipping the switch to RUN again. EDIT: Why is there no Cockpit Video Recorder? The…

> EDIT: Why is there no Cockpit Video Recorder? The days of limited storage are over.

Pilots unions are dead against it.

Re: Preliminary report into Air India crash released

#37
post #19

> The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. So the fuel supply was cut off intentionally. The swi…

Yeah and the other pilot flipped the switches back on and one of the engines started spooling up but it was too late. Murder-suicide looks like the likely conclusion, given that flipping the cutoff switches requires a very deliberate action. That said, it's not entirely impossible that due to stress or fatigue the pilot had some kind of mental lapse and post-flight muscle memory (of shutting off the engines) kicked i…

> post-flight muscle memory (of shutting off the engines) kicked in

Possible, and if so it is too early to conclude it was murder-suicide.

See also: https://www.thehindu.com/news/national/dgca-slaps-80-lakh-fi...

Re: Preliminary report into Air India crash released

#38
post #22

Earlier quoted context omitted.

You have to pull the switches out (against a spring) to be able to move them over a notch and flip them. Not really something you can just mistake for another switch or bump into by accident. I'd liken it to turning off the ignition by turning the key while driving your car. Possibly something that could happen if you're really fatigued, but requires quite a mental lapse.

Report says the switches went to cutoff one second apart from each other. Can a human do the physical operation on two switches that quickly?

The timing is really curious.

08:08:35 Vr

08:08:39 Liftoff

08:08:42 Engine 1 cut-off

08:08:42 Engine 2 cut-off

08:08:47 minimum idel speed reached

?? One pilot to other: why cut-off. Other: Did not do it

08:08:52 Engine 1 run

08:08:52 Engine 2 run

1 second to switch them both off and then 4 seconds to switch them both on. No one admitted to switch them off. They are probably going with fine comb over the audio and also the remains of the chared switches.

Looks like the engines react very quickly to cut-off so it is not clear whether the question about the cut-off is prompted by a glance to the switches or the feel of the airplane.

The big question is whether the switches were moved or something made it seem as if the switches were moved.

Re: Preliminary report into Air India crash released

#39
post #19

Earlier quoted context omitted.

Yeah and the other pilot flipped the switches back on and one of the engines started spooling up but it was too late. Murder-suicide looks like the likely conclusion, given that flipping the cutoff switches requires a very deliberate action. That said, it's not entirely impossible that due to stress or fatigue the pilot had some kind of mental lapse and post-flight muscle memory (of shutting off the engines) kicked i…

> post-flight muscle memory (of shutting off the engines) kicked in Possible, and if so it is too early to conclude it was murder-suicide. See also: https://www.thehindu.com/news/national/dgca-slaps-80-lakh-fi...

The report shows 0 flight hours during the prior 24 hours for both pilots, and 7 hours and 6 hours each for the previous 7 days. It seems they were both fresh pilots for this flight.

Re: Preliminary report into Air India crash released

#40

> The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. So the fuel supply was cut off intentionally. The swi…

> It's difficult to conclude anything other than murder-suicide. Is it possible it could have been an accident or a mistake by one of the pilots? How intention-proofed are engine cutoffs?

It could be defective switch springs, fatigue-induced muscle memory error, or something else. The pilot who did it saying he did not may not have realized what he did. It's pretty common under high workload when you flip the wrong switch or move a control the wrong way to think that you did what you intended to do, not what you actually did.

That said Boeing could take a page out of the Garmin GI275. When power is removed it pops up a "60s to shutdown dialog" that you can cancel. Even if you accidentally press SHUTDOWN it only switches to a 10s countdown with a "CANCEL" button.

They could insert a delay if weight on wheels is off. First engine can shutdown when commanded but second engine goes on 60s delay with EICAS warning countdown. Or just always insert a delay unless the fire handle is pulled.

Still... that has its own set of risks and failure modes to consider.

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