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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

#501

Post by shash »

crtified wrote: post #184
userbinator wrote: post #158

Earlier quoted context omitted.

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…

I agree, there's a significant distinction between "the switches were (physically) flipped" and "the circuit was opened/closed". In this case, it may be a moot distinction, particularly if no physical evidence of fault or tampering has been discovered in investigation. But, in theory, very important - there's a lot of potential grey-area between the two statements. The proximity of the incident to the ground may also…

My understanding from what we've been reading is that these are physical switches that cannot be moved using remote triggers. Wildly speculating, there _may_ be a possibility that the _effect_ of the switch may be triggered remotely, if it's a signal being read by a control unit or computer of some sort that then actuates the specific electromechanical components. But it would seem impossible to move a physical switch to do it.

As an analogy, if you have a smart lock, you can remotely trigger the _effect_ of turning the key using (let's say a bluetooth control), but if a key is inserted into the keyhole, unless there is two-way mechanical linkage, that key _will not turn_.

Re: Preliminary report into Air India crash released

#502

Post by jltsiren »

sailingparrot wrote: post #491
burnt-resistor wrote: post #326

Earlier quoted context omitted.

> cannot be mistaken for something else Assumption. Big ass assumption. Pilot are trained until actions are instinctual and certain memory items are almost unconscious. But pilots are still people and people are fallible and make mistakes, and sometimes act unreasonably. Intent cannot be determined without clear evidence or statements because that's now how thoughts locked away in people's minds work. > It's not arro…

> sometimes act unreasonably. Intent cannot be determined without clear evidence or statements because that's now how thoughts locked away in people's minds work. By this logic it would be impossible to ever find anyone guilty of murder (or any other nefarious action) with intent unless they explicitly state that it was in fact their intent. Obviously this is not how justice works anywhere, because at some point you…

Courts do not seek to establish the truth. They aim for a reasonable balance between false positives (innocents convicted of crimes they didn't commit) and false negatives (criminals allowed to go free). In practice, the false positive rate is probably around 5%, and innocents go to prison all the time.

Air accident investigations mostly deal with one-in-a-billion freak occurrences. Commercial aviation so safe and reliable that major accidents rarely happen without a truly extraordinary cause.

Re: Preliminary report into Air India crash released

#503

Post by shash »

userbinator wrote: post #454
__turbobrew__ wrote: post #49

Earlier quoted context omitted.

I wonder if the switches are still in tact after the crash? Can they verify that the switches are mechanically sound? If so, seems highly likely it was intentional.

I'd suspect the wiring leading from the switches to the engine controllers first, especially since it looked like both circuits cut out nearly at the same time.

This is speculation again since I don't really know, but my understanding of aviation engineering is that there would be two separate controllers for each engine connected to these two switches. At no point would they be connected to the _same_ control unit. The really short time (~1s) between the two being cutoff is the difficult thing to explain here.

Re: Preliminary report into Air India crash released

#504

Post by dxdm »

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.

> Again, it’s probably pointless but it’s an interesting thought exercise.

Coming up with ad-hoc solutions is easy, especially the less you know about a complex system and its constraints. I'd say it's not an interesting exercise unless you consider why a solution might not exist already, and what its trade-offs and failure modes are. Otherwise, all you're doing is throwing pudding against a wall, which can of course be fun.

Re: Preliminary report into Air India crash released

#506

Post by 7952 »

fosk wrote: post #472
Jtsummers wrote: post #39

Earlier quoted context omitted.

The report shows 0 flight hours during the prior 24 hours for both pilots, and 7 hours and 6 hours each for the previous 7 days. It seems they were both fresh pilots for this flight.

0.1% of airline pilots fly intoxicated, and probably many more fly hangover which is an undetectable condition. There is speculation that in the Air France flight 447 that crashed into the ocean en route to Paris, one or the pilots only had 1h of rest because of partying the night before. Of course it’s all speculative, and however unlikely it is, eventually it’s bound to happen that we get pilots with poor mental cl…

At some point I think we need to accept more control from automation. The model where ultimate authority reverts to a single input is a cop out. That could be pilot input, sensor input or even direction from ATC. They will all provide false data on occasions. When that data contradicts 99% of the other data then the safest option is to ignore it. And that doesn't just mean with compromised humans but with normal human weakness. Fully understanding the aircraft, its state, its systems and the minds of its crew is impossible.

In this case I wonder if the fuel cut off switches could be replaced by buttons for particular situations. Have an engine fire button or a shut down whilst on the ground button. Let the pilot provide input on state and let the automation decide what to do with that. Obviously this is not a solution to suicidal or murderous behaviour. But it could be a solution to all the low probability edge cases.

Re: Preliminary report into Air India crash released

#507

Post by VBprogrammer »

longos wrote: post #134
sillysaurusx wrote: post #50

Earlier quoted context omitted.

https://www.youtube.com/live/SE0BetkXsLg?si=LPss_su3PVTAqGCO Both of these extremely-experienced pilots say that there was near zero chance that the fuel switches were unintentionally moved. They were switched off within one second of each other, which rules out most failure scenarios. If it was an issue with the switches, we also would have seen an air worthiness directive being issued. But they didn’t, because this…

If this is what actually happened it would be the second in recent memory: https://en.wikipedia.org/wiki/Germanwings_Flight_9525 .

It feels quite uncomfortable to me. I remember using this exact example of why the changes after the German wings crash wouldn't prevent a murder suicide in the future.

Re: Preliminary report into Air India crash released

#508

Post by refulgentis »

Aeolun wrote: post #409
refulgentis wrote: post #240

Earlier quoted context omitted.

Free memento mori: you're both free-associating. There's 0 reason to conclude murder-suicide, there's an infinitude of things that could have the same result, and both pilots denied it to eachother: how is that presented as proof ? I hope I don't need to explain why the fact no one knew in advance the Las Vegas shooter was going to shoot has ~0 similarities with the situation as we know it, and banal similarities wit…

Using that reasoning all airplane crashes have a lot in common too. Doesn’t mean the ones where you cannot determine the reason and have to speculate don’t suck.

Could you explain more? There's too many negatives in that last sentence for my decaffeinated early morning brain. I'm titillated by the idea there's a way to justify making up things so I really want to parse it.

Re: Preliminary report into Air India crash released

#509

Post by tiahura »

ExoticPearTree wrote: post #313
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 both pilots deny doing it. > It's difficult to conclude anything other than murder-suicide. You’re trying to prove a negative here. I am not familiar with the 787 operations, but there are a few issues that need to be sorted out first: - altitude when pilots start the after takeoff checklist - if there are any other switches that are operated in tandem in the general vicinity of where the engine cutoff switches…

Have you ever turned your car off when you meant to turn on the windshield wiper?

Re: Preliminary report into Air India crash released

#510

Post by briandear »

lazystar wrote: post #17
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…

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…

You don’t inadvertently turn off both switches. The linked SAIB was in 2018 and addresses faulty installations, not a failure after use. And preflight over thousands of flights would have detected if the switches had a failed locking mechanism. And for both to fail at once? Practically impossible. Also the recommended inspection — that was almost 7 years ago. If a major airline didn’t comply with the SAIB, that’s on them, not Boeing. There hasn’t been a single reported instance of fuel switches being accidentally switched off on any Boeing airliner — in 320 million flight hours over the past 10 years.
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