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Preliminary report into Air India crash released

bbc.co.uk

351–360 of 924 posts

Re: Preliminary report into Air India crash released

#351
post #92

Earlier quoted context omitted.

Cutting fuel just after takeoff leaves almost zero time for the other pilot to recover.

It's interesting to try to imagine a device that would prevent that, without causing more issues. My preliminary idea is a "fuel bladder" for take-off that inflates with enough fuel to get the plane to a recoverable altitude, maybe a few thousand feet?

Or you simply interlock the engine cutoff with the thrust lever position, any position other than idle prevents shutdown. This all goes through the flight computers already.

If there’s a fire or similar problem the fire handles will cut off fuel without the normal shutdown procedure, but the normal switches only need to be used at idle thrust.

I wonder if Airbus has this logic, since their philosophy is to override the pilot commands if they’d endanger the aircraft (which has its own issues of course) where’s Boeing will alert the pilots and still perform the action. I don’t have access to that information.

Re: Preliminary report into Air India crash released

#353
I'm completely ignorant about this matter, but why is it even possible to cut off fuel while taking off? Shouldn't there be a control that completely disables this? Is there actually a situation where cutting off both engines could be necessary and wouldn't lead to a catastrophe?

Re: Preliminary report into Air India crash released

#354
post #33

Earlier quoted context omitted.

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.

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.

Re: Preliminary report into Air India crash released

#355
post #205

Earlier quoted context omitted.

I can't put my car into reverse gear while driving down the freeway.

You also can't reverse a plane while flying it... This is a rather odd comparison. You can slam the brakes, yank the steering week, and do all sorts of things to intentionally make the car crash.

You can put the reversers on for a tactical descent though :P

Re: Preliminary report into Air India crash released

#356

Earlier quoted context omitted.

Is actuating the fuel cutoff switches something that is done routinely in these aircraft, to the extent it could reasonably become muscle memory? ETA: downthread it is mentioned that these switches are used on the ground to cut the engines

Seems akin to something like a parking brake. Something you only use at a stop, or rarely during an emergency.

Was amused to see they have one of those too, with "parking brake" written on it.

Re: Preliminary report into Air India crash released

#357

Earlier quoted context omitted.

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 re…

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?

Re: Preliminary report into Air India crash released

#358

Earlier quoted context omitted.

Fire isn't the only instantly severe problem with engines. Another is violent shaking if, say, part of the rotating assembly came off.

Yep. Fan blade off, shroud separation, HP disc separation, compressor stall, FOD ingestion/bird strike, EGT rise, oil system issues. Very unlikely events but still possible events that need a prepared response to and capabilities to manage the aircraft. The presumption is that the crew is trained, diligent, disciplined, and concerned with survival. Without that, aircraft would need to be unmanned and flown by AI lack…

I'm not sure you want a creative AI flying a plane anyway.

Re: Preliminary report into Air India crash released

#359

I'm completely ignorant about this matter, but why is it even possible to cut off fuel while taking off? Shouldn't there be a control that completely disables this? Is there actually a situation where cutting off both engines could be necessary and wouldn't lead to a catastrophe?

Engine fire requires you to cut fuel to the affected engine.

Re: Preliminary report into Air India crash released

#360
post #33

Earlier quoted context omitted.

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.

Those switches are the size of a thumb. No one is moving those - separately, mind you - and not realize what is going on.
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