Comment by alephnerd
2 days ago
> 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?
2 days ago
> 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?
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.
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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.
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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.
When your engine catches on fire/blows apart on takeoff you want to cut fuel as fast as possible.
If its both engines you're fucked anyway if its shortly after takeoff.
But I'm an advocate of KISS. At a certain point you have to trust the pilot is not going to something extremely stupid/suicidal. Making overly complex systems to try to protect pilots from themselves leads to even worse issues, such as the faulty software in the Boeing 737-MAX.
Was thinking this same thing. A minute feels like a long time to us (using a Garmin as the example said) but a decent number of airplane accidents only take a couple minutes end to end between everything being fine and the crash. Building an insulation layer between the machine and the experts who are supposed to be flying it only makes it less safe by reducing control.
Proposed algorithm: If the flight computer thinks the engine looks "normal", then blare an alarm for x seconds before cutting the fuel.
I wonder if there have been cases where a pilot had to cut fuel before the computer could detect anything abnormal? I do realize that defining "abnormal" is the hardest part of this algorithm.
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Delay is probably worse - now you're further disassociating the effect of the action from the action itself, breaking the usual rule: if you change something, and don't like the effect, change it back.
This makes me wonder. Is there no audible alarm when the fuel is set to cutoff?
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I'm doing it all the time while rebasing commits or force pushing to my branch. Sometimes I would just click the wrong buttons and end up having to stay late to clean the mess. It's a great thing I'm not a pilot. I would be dead by now.
[flagged]
Please don't sneer, including at the rest of the community.
https://news.ycombinator.com/newsguidelines.html
This is a place that puts "Hacker" in the name despite the stigma in the mainstream. Given the intended meaning of the term, I would naturally expect this to be a place where people can speculate and reason from first principles, on the information available to them, in search of some kind of insight, without being shamed for it.
You don't have to like that culture and you also don't have to participate in it. Making a throwaway account to complain about it is not eusocial behaviour, however. If you know something to be wrong with someone else's reasoning, the expected response is to highlight the flaw.
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Yeah, people shouldn't bat ideas around and read replies from other people about why those ideas wouldn't work. Somebody might learn something, and that would be bad.