Comment by ummonk
2 days ago
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.
Is it possible to rest the switch on the notch? Does the switch make contact if the switch is in the RUN position but the switch is not completely down?
That is, is it possible they flipped the switches over to RUN but did not seat the switches properly, and instead leaving them on top of the notch, with later vibration causing the switches to disengage?
Just trying to think of some semi-plausible non-active causes.
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.
Well in the murder-suicide scenario it makes sense for the culprit to turn them off as quickly as possible. The longer time to turn them on could plausibly be a struggle or simply needing to fly the plane while reaching for each switch individually.
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> 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 workload is pretty high during the takeoff phase. The engines react right away when fuel flow is stopped. The engine displays can have some lag before data is updated.
Relighting an engine at low speed is not feasible - most need 230-250kts IAS before attempting the operation. Maybe you could do it if the APU was still running and could provide compressed air, but it takes about 20-30 seconds to start up amd then probably 5-10 more to spool up to full thrust. I am speculating here a bit, but the pilot did not have enough time to save the plane even if he did everyting right and as fast as humanly possible.
All this aside is overshadowed by the limited amount of time the pilot flying (I would assume the captain in this case since there was only one ATPL pilot in the cockpit) had to troubleshoot the issue of a dual engine failure - as this is what would have felt to him - during takeoff.
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There's a good photo of them here; https://theaircurrent.com/aviation-safety/ai171-investigatio...
You can do them both with one hand.
Are you completely sure you can considering that they are spring loaded and they are like 7-10cm apart judging by the size of other controls?
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I wonder if they could theoretically rest on top of the notch, not fully locked into either position and flip accidentally. No idea how the switches behave when not all the way up or down, but the notch looks pretty long and flat so it could be possible.
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Those switches are the size of a thumb. No one is moving those - separately, mind you - and not realize what is going on.
If you do them both with one hand, would they not be moved at the same instant rather than 1 second apart?
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Is there just one set of switches? Or do both pilots have their own set?
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