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Preliminary report into Air India crash released

bbc.co.uk

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Re: Preliminary report into Air India crash released

#141

Post by cjbprime »

darth_avocado wrote: post #85
lazystar wrote: post #17

Earlier quoted context omitted.

https://ad.easa.europa.eu/ad/NM-18-33 well hold your horses there... from the FAA in their 2019 report linked above: > The Boeing Company (Boeing) received reports from operators of Model 737 airplanes that the fuel control switches were installed with the locking feature disengaged. The fuel control switches (or engine start switches) are installed on the control stand in the flight deck and used by the pilot to sup…

One would assume a toggle like that would come with blaring alarms and blinking lights… right? Right?? Edit: It also seems like the engine cutoff is immediate after the toggle. I wonder if a built in delay would make sense for safety.

> I wonder if a built in delay would make sense for safety.

(Presumably delaying the amount of time before a raging engine fire stops receiving fuel would also have an impact on safety?)

Re: Preliminary report into Air India crash released

#142

Post by pixl97 »

xenadu02 wrote: post #40
alephnerd wrote: post #14

Earlier quoted context omitted.

> 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 re…

When your engine catches on fire/blows apart on takeoff you want to cut fuel as fast as possible.

Re: Preliminary report into Air India crash released

#143

Post by pixl97 »

dcreater wrote: post #140
stefan_ wrote: post #59

Earlier quoted context omitted.

And then 10s later the switches magically fixed themselves? The likely not electronically connected switches since that would compromise engine redundancy?

intermittent state switching is absolutely a thing in (poorly designed/manufactured/tested/QC'd) electronics

It is, and one would expect that a single switch failure would be far more probable, so how often have we had switch failure single engine cutoff in the 787?

Re: Preliminary report into Air India crash released

#144

Post by analog31 »

tim333 wrote: post #109
marze wrote: post #82

Earlier quoted context omitted.

You mention "brain fart". There is certainly a long history of pilots selecting the wrong lever, or wrong switch. So, it is possible the pilot who denied switching the fuel off thought he had switched something else.

If you look at the photo https://theaircurrent.com/aviation-safety/ai171-investigatio... it would be pretty hard to get them by mistake.

I have a couple of those type of switches, though smaller, in my parts bin. They were from some piece of surplus equipment that got junked. Where I've seen them used is in a crowded control panel where they might just get bumped. The two red plastic levers to the left are another type of safety switch: The lever is spring loaded, and covers the handle of a toggle switch.

In my view it would be quite hard to move them by accident, and probably not possible to move at once.

It would be interesting to know if the plane has any other switches of the same type, that are routinely activated.

Re: Preliminary report into Air India crash released

#146

Post by alvah »

sillysaurusx wrote: post #65
suyash wrote: post #62

Earlier quoted context omitted.

Is there a possibility that they got hacked and remotely toggled ?

Sadly not. It’s a physical switch with no capability of a remote toggle. The flight data recorder clearly shows one was toggled off within a second of the other, which rules out almost every non-intentional scenario.

Happily not. If this were possible, it would open up a whole universe of problems.

Re: Preliminary report into Air India crash released

#147

Post by bob1029 »

jeffbee wrote: post #119
comrade1234 wrote: post #112

Why can the pilot shut off the fuel during takeoff?

Suggest a system that would prevent this, but only this, without causing other risks.

Disable the fuel system cutoff controls during the takeoff climb phase of flight. Once the aircraft loses contact with the runway, these controls shouldn't function without tripping certain thresholds (speed & altitude), or following a two-man procedure that is physically impossible to execute solo. In any other flight regime, the controls function as originally designed.

The danger of a burning engine is irrelevant if you are heading into terrain.

Re: Preliminary report into Air India crash released

#148

Post by ls-a »

decimalenough wrote: post #11

> 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…

So you're telling me that those switches don't have a voice that says "fuel cutoff switches transitioned" like in the movies? That's bad design

Re: Preliminary report into Air India crash released

#149

Post by OneMorePerson »

pixl97 wrote: post #142
xenadu02 wrote: post #40

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…

When your engine catches on fire/blows apart on takeoff you want to cut fuel as fast as possible.

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.

Re: Preliminary report into Air India crash released

#150

Post by cosmicgadget »

mvdtnz wrote: post #135
cosmicgadget wrote: post #114

Earlier quoted context omitted.

Did you mean to say you can activate the switches with one hand simultaneously ? That is probably what the above commenter assumed you meant. Since lifting and twisting two switches simultaneously with one hand seems challenging.

It didn't happen simultaneously so this is irrelevant.

It is relevant to the interaction I replied to.
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