Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Preliminary report into Air India crash released

bbc.co.uk

Post reply on HN
Print view View original

91–100 of 924 posts

Re: Preliminary report into Air India crash released

#91

Post by rogerrogerr »

acjohnson55 wrote: post #73
sillysaurusx wrote: post #65

Earlier quoted context omitted.

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.

What if he mistook the switch for a different switch?

It's an entirely different shape, different location, and different motion from any other switch they could be looking for. Suicide is a way more likely explanation.

And, it's _two_ switches.

Re: Preliminary report into Air India crash released

#92

Post by bombcar »

cosmicgadget wrote: post #51
lazystar wrote: post #44

Earlier quoted context omitted.

still, it at least shows that there's been issues with the locking mechanism in the past. inadvertently bumping something that was assumed to be locked is a simpler theory; i find it hard to believe that a murder suicider would take this route, when the china nosedive option is easier, faster, and has a higher chance of success.

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?

Re: Preliminary report into Air India crash released

#93

Post by anonymousiam »

rogerrogerr wrote: post #84
anonymousiam wrote: post #71

Earlier quoted context omitted.

The report says the co-pilot was flying. The report says the black box reports the fuel cutoff switches being activated. That doesn't necessarily mean that either of the two pilots activated them, it just means that the fly-by-wire system reacted to a fuel cutoff event. "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 fue…

> That doesn't necessarily mean that either of the two pilots activated them It does: 1. Those switches have physical interlocks and cannot be manipulated by any computer system. 2. The flight data recorder is measuring the position of the switches; they aren't inferring the position from some system state. There's a "position of this switch" channel. The switches were physically moved in the cockpit, that's basicall…

What is the path of the wires from the switch onward? Do they go into a digital input of the flight computer, or do they directly feed the fuel control valves?

https://simpleflying.com/boeing-787-technical-features-guide...

" Advanced electric controls

The 787 entered service with an improved fly-by-wire flight control system. Rather than mechanical processes, the systems convert flight deck crew inputs into electrical signals. Still, there were additional advancements with the type."

Re: Preliminary report into Air India crash released

#95

Post by arcfour »

sillysaurusx wrote: post #57

[flagged]

As someone with no qualifications on this beyond occasionally playing some flight simulators, I can't think of a reason you would ever intentionally move the switches in flight (barring an emergency like a leak or fire or something) and unintentionally doing so seems extremely unlikely since generally "switches meant to be operated on the ground" are located well out of the way of "switches meant to be operated in flight". Though I believe Boeing does have them by the thrust levers, every type of fuel control switch I've seen has some sort of guard or mechanism that makes it effectively impossible to move the switch by simply bumping it.

So I can't imagine how it could have been done accidentally.

Re: Preliminary report into Air India crash released

#96

Post by lazide »

stefan_ wrote: post #59
dcreater wrote: post #46

Earlier quoted context omitted.

Do you know if the mechanical position of the switch guarantees its electronic state without any possibility for hardware malfunction? If no, then you are claiming a person made one of the most grave acts of inhumanity ever. This sounds to me like an electronics issue - an intermittent, inadvertent state transition likely due to some PCB component malfunction

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

The other pilot likely flipped them back - but at that point, it was impossible to avoid crashing.

Re: Preliminary report into Air India crash released

#97

Post by [deleted] »

sillysaurusx wrote: post #80
janice1999 wrote: post #77

Earlier quoted context omitted.

> If I’m wrong, I’ll hang up my hat and never cover live news again. It easy to say that when you know there's likely no way to prove or disprove whether it as an accident or not. Unless a pilot left a note stating his future intentions, there's no way to determine their state of mind.

Someone took their hand, pulled one spring-loaded switch into the off position, and then did it the other switch moments later. Is there any way that could be accidental? If there was no mechanical failure, the only remaining possibility is deliberate action. And if it was mechanical failure, we’d see an emergency air worthiness directive being issued, which we haven’t.

[deleted]

Re: Preliminary report into Air India crash released

#98

Post by rogerrogerr »

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…

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.

Re: Preliminary report into Air India crash released

#99

Post by bombcar »

ssl232 wrote: post #35
bgwalter wrote: post #25

Earlier quoted context omitted.

Does the Flight Data Recorder consider the physical position of the fuel switches or does it get the information from some fly-by-wire part that could be buggy? The conversation would suggest that the switches were in CUTOFF position, but there is also a display that summarizes the engine status. There is no conversation that mentions flipping the switch to RUN again. EDIT: Why is there no Cockpit Video Recorder? The…

> EDIT: Why is there no Cockpit Video Recorder? The days of limited storage are over. Pilots unions are dead against it.

And now some pilots are dead.

Just allow cockpit video recorders, and if they're ever used for anything, the pilots (or their heirs) get $250k in cash.

Re: Preliminary report into Air India crash released

#100

Post by rogerrogerr »

codefeenix wrote: post #87
fsckboy wrote: post #72

it makes sense to me that the pilot who said "I did not do it" actually did do it without realizing it, was supposed to be putting the landing gear up when he committed a muscle memory mistake. it happened around the time the landing gear should be up, and this explanation matches what was said in the cockpit, and the fact that the landing gear wasn't retracted. I think this idea was even floated initially by the you…

even though that raising the gear is a up motion and fuelcut off is a down motion?

And fuel cutoff is _two_ down motions? That's the death knell for this theory, imo.
Post reply on HN