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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

#211

Post by Epa095 »

userbinator wrote: post #158
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…

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 Or more precisely, the signals which come from them were found to behave as such. Without any audible record of turning the switches off, I wouldn't blame the pilots without first checking the wiring and switches themselves for faults. This reminds me of the g…

But from the audio recording it seems like one pilot is noticing them bering in the CUTOFF position, and asking why (and moving it back). If the switch was actually in RUN, but some other issue caused the signal to be sendt, the pilot would see it beeing in the RUN position, not CUTTOF.

Re: Preliminary report into Air India crash released

#213

Post by Epa095 »

userbinator wrote: post #193
ceejayoz wrote: post #15

Earlier quoted context omitted.

Both switches, at slightly different times? Seems pretty unlikely.

A rodent chewing on wires. Vibration-induced chafing. Tin whiskers causing an intermittent short. There are many possibilities, those came to mind first.

But why does the pilot then comment that they are in the CUTTOF position and move it to RUN? A mechanical failure would have to also move the physical switch in the cockpit for the audio recording to make sence.

Re: Preliminary report into Air India crash released

#214

Post by stephen_g »

bombcar wrote: post #154
cosmicgadget wrote: post #129

Earlier quoted context omitted.

I think engine fires are still more common than suicidal pilots and inadvertant fuel shutoff activations.

The idea would be something that is ONLY operational after V₁ and until some safe height. Or maybe a design that prevents both switches being off (flip flop?) for X minutes after wheel weight is removed? Again, it’s probably pointless but it’s an interesting thought exercise. Suicidal pilots are apparently more common than we’d want.

It’s a pointless exercise though - if one of the pilots wants to crash the plane, there’s almost nothing that can possibly be done. Only if someone can physically restrain them and remove them from the controls.

There’s always going to be many ways they could crash the plane, such a feature wouldn’t help. The pilots are the only people you can’t avoid fully trusting on the plane.

Re: Preliminary report into Air India crash released

#215

Post by sgentle »

dboreham wrote: post #171
baseballdork wrote: post #125

Earlier quoted context omitted.

Fire, probably. But also, how complicated would you make the system if you needed to prevent certain switches from working during certain times of flight? At some point... we're all just in the hands of the people in the cockpit.

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

Sure, but you can open the door, pull the handbrake, or turn the wheel so hard you lose control of the vehicle. These are all similarly preventable, but maybe not worth the risk of being unable to open the door, brake or steer if the safety mechanism fails closed, or if your situation is outside the foresight of its designer.

Also, you don't need multiple certifications and 1500 hours of experience to drive a car.

Re: Preliminary report into Air India crash released

#217

Post by p1mrx »

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.

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.

Re: Preliminary report into Air India crash released

#218

Post by userbinator »

Epa095 wrote: post #213
userbinator wrote: post #193

Earlier quoted context omitted.

A rodent chewing on wires. Vibration-induced chafing. Tin whiskers causing an intermittent short. There are many possibilities, those came to mind first.

But why does the pilot then comment that they are in the CUTTOF position and move it to RUN? A mechanical failure would have to also move the physical switch in the cockpit for the audio recording to make sence.

You have the exact CVR audio? The report says "one of the pilots is heard asking the other why did he cutoff" which I interpreted to mean one of them noticed the engines shutting down, and asked the other if he did that.

Re: Preliminary report into Air India crash released

#219

Post by groos »

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…

Suicide is quite a stretch without any supporting evidence from the pilots' backgrounds. I would take mental fog, cognitive overload, wrong muscle memory, even a defective fuel cutoff system over suicide.

Re: Preliminary report into Air India crash released

#220

Post by resist_futility »

deadbabe wrote: post #216
resist_futility wrote: post #209

In this YouTube short you can see the pilot switching both fuel cutoff to run https://www.youtube.com/shorts/bd4Bler36Nk

there's literally two other similar switches right next to those?

The switches on the lower panel that are switched, are the fuel cutoffs
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