Preliminary report into Air India crash released • Hacker News Board

Re: Preliminary report into Air India crash released

#611

Post by ufmace » Sat, Jul 12, 2025, 2:41 PM UTC

yallpendantools wrote: post #340

ls-a wrote: post #148

Earlier quoted context omitted.

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

I know this thread runs the gamut of armchair experts, pretend experts, and actual experts and there's no telling who is which but I really want to know why the downvotes and why this is not a good idea. The idea is to notify for crucial settings, replace vocal confirmation (probably) already in the SOP anyway, reducing mistakes in bad faith or otherwise. Don't some planes already have an automated announcement for s…

Pretty obviously a bad joke and a bad idea IMO. I did not personally downvote, but I think it deserves its current score.

Look at the timeline of the events. The switches were shut off, noticed to be shut off, and restored to the proper position within 10 seconds with the current system. Insufficient notification that the switches have been turned off was clearly not a problem in need of a solution. It would be slower and more challenging to understand an automated verbal announcement than the surely extremely obvious sudden lack of thrust and all engine dials rapidly dropping to zero.

So it wouldn't contribute at all to solving this particular case, would only be a slightly annoying distraction in the more normal case of normal aircraft shut-down after completing its flights, and would be a potentially hazardous distraction in the intended emergency case of engine is on fire and fuel must be cut off immediately, where there's probably a bunch of other extremely important and urgent things to pay attention to and do other than a silly automated warning telling you what you just did.

Re: Preliminary report into Air India crash released

#612

Post by anton-c » Sat, Jul 12, 2025, 2:43 PM UTC

bravesoul2 wrote: post #533

timeon wrote: post #415

Earlier quoted context omitted.

You know what? I'm just not going to fly - ever.

Your choice but safer to fly than drive the same journey. Commercial airliners anyway.

Yes I acknowledge this. But I also retain control to the very last moment. I don't have to bank on the driver of my vehicle not being suicidal. If I feel another driver is dangerous, I can just stop. This obviously doesnt prevent all accidents but I've never been in a serious one.

That being said ive flown plenty of times. My fear comes from lacking any control and just finding out mid-flight were going down through no fault of my own. I wouldn't want to know, but then again air France 447 is terrifying too.

Re: Preliminary report into Air India crash released

#613

Post by agubelu » Sat, Jul 12, 2025, 2:46 PM UTC

zarzavat wrote: post #561

Mawr wrote: post #453

Earlier quoted context omitted.

That's a ridiculous analogy. The pilots aren't sitting in front of a uniform set of keys that they need to press in a specific order with a specific timing. The mistake equivalent to what the pilot supposedly did would be if the pianist accidentally stuck a finger up his nose instead of playing the notes or something.

Quite, but the point is that even after doing something correctly a thousand times, someone can make a mistake that seems unbelievable. The cutoff switches are operated every flight so the muscle memory is there, ready to be triggered at the wrong time. All we know is that something went wrong in the pilot's head in at least a single moment that caused him to perform a ground action during takeoff. Depressive murder-…

I keep reading "muscle memory" but the theory that one pilot shut down the engines instead of performing another action has nothing to do with muscle memory.

Muscle memory allows you to perform both actions effectively but doesn't make you confuse them. Especially when the corresponding sequence of callouts and actions is practiced and repeated over and over.

All of us have muscle memory for activating the left blinker in our car and pulling the handbrake, but has anyone pulled the handbrake when they wanted to signal left?

Re: Preliminary report into Air India crash released

#614

Post by fosk » Sat, Jul 12, 2025, 2:50 PM UTC

labcomputer wrote: post #602

fosk wrote: post #493

Earlier quoted context omitted.

This is actually very clever and elegant!

Well.. except that it means you can’t turn off the engines if the throttle encoder fails.

Actually the parent comment was wrong:

You can physically cut off fuel without pulling the thrust lever to idle, because the two are separate controls.

However, it’s against procedure to do so - even dangerous. Throttle should always be at idle before pulling the cutoff switch, because otherwise excessive pressure can be created in the fuel system.

Essentially this is just a best practice, but there is no interlock between throttle and fuel cut off.

Then I got intrigued by your comment in case the throttle encoder fails. Turns out there is double redundancy on the throttle encoder (if one computer fails, the next one takes over), and if both fail the airplane will run on the last known setting at which point the only possible action that can be taken is to cut off the fuel (or keep it running with the last known throttle level).

In this regard both Boeing and Airbus follow the same implementation and there is no difference whatsoever between them.

Perhaps something they I have learned is that cutting off fuel during max throttle position (take off) may have damaged the fuel system of the Air India airplane because of big pressure in the lines and that may have interfered with the restart of the engines when the fuel valve was opened again.

Re: Preliminary report into Air India crash released

#615

Post by ufmace » Sat, Jul 12, 2025, 2:52 PM UTC

bob1029 wrote: post #147

jeffbee wrote: post #119

Earlier quoted context omitted.

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…

I don't think so. A moderately hard landing with an engine(s) smoldering because they were on fire but had their fuel cut off is probably survivable for most of the passengers. A moderately hard landing with the engine(s) a raging inferno pouring burning fuel all over the place because the fuel couldn't be cut off or took too long to do so is much less survivable.

Putting complex and fallible restrictions on safety-critical controls like fuel cutoff is usually a bad idea overall.

Re: Preliminary report into Air India crash released

#616

Post by agubelu » Sat, Jul 12, 2025, 2:53 PM UTC

potamic wrote: post #471

nottorp wrote: post #408

Almost 400 comments and no avherald link for reference? https://avherald.com/h?article=528f27ec

> On Jul 12th 2025 (UTC) India's media report that the investigation is NOT focussing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure. Service Bulletins by Boeing issued in year 2018 recommending to upgrade the fuel switches to locked versions to prevent inadvertent flip of the switches, as well as the FAA/GE issued Service Bulletin FAA-2021-0273-0013 Attachment 2…

Respectfully, media reports on what the investigation is focusing on should be taken with a grain of salt unless said media is known to be reputable and have credible sources.

If they had a credible indication of a technical failure that causes engines to randomly shut down, they would have already grounded 787 fleets, which hasn't happened.

Re: Preliminary report into Air India crash released

#617

Post by losvedir » Sat, Jul 12, 2025, 2:54 PM UTC

macintux wrote: post #245

747fulloftapes wrote: post #139

Earlier quoted context omitted.

The landing gear lever is rather prominently featured in the 787 in a panel central to the cockpit layout so that either pilot can easily reach it. For decades and across many manufacturers, the landing gear lever has traditionally featured a knob that deliberately resembles an airplane wheel. It's very hard to mistake it for anything else. It's actuated by simply moving it up or down. The fuel control switches are b…

> This idea strikes me as even more unlikely than someone shifting their moving vehicle into reverse while intending to activate the window wipers. I suspect you've never driven an older vehicle with the shifter on the steering column.

Or a Tesla. I've done this exact thing, although the car just beeped at me and refused to go into reverse, of course.

Re: Preliminary report into Air India crash released

#618

Post by agubelu » Sat, Jul 12, 2025, 3:02 PM UTC

jltsiren wrote: post #502

sailingparrot wrote: post #491

Earlier quoted context omitted.

> 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 re…

Yet Occam's razor still applies

Re: Preliminary report into Air India crash released

#619

Post by nottorp » Sat, Jul 12, 2025, 3:06 PM UTC

VBprogrammer wrote: post #535

potamic wrote: post #471

Earlier quoted context omitted.

> On Jul 12th 2025 (UTC) India's media report that the investigation is NOT focussing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure. Service Bulletins by Boeing issued in year 2018 recommending to upgrade the fuel switches to locked versions to prevent inadvertent flip of the switches, as well as the FAA/GE issued Service Bulletin FAA-2021-0273-0013 Attachment 2…

My concern would be that the investigation in this case is more likely to be biased towards a system failure. Disgracing a major flag carrier is something very few regulars have the independence and courage to get away with.

The way i read what avherald highlighted is that a part that the manufacturer said should be replaced wasn't and failed as the manufacturer said it will. So it would point to the airline maintenance right now.

What the bbc says is truncated and omits the info about the failing part, so people can point towards murder suicide because they don't have all the info.

Which is why you should always read avherald first...

Re: Preliminary report into Air India crash released

#620

Post by brookst » Sat, Jul 12, 2025, 3:15 PM UTC

malfist wrote: post #551

russdill wrote: post #124

Earlier quoted context omitted.

There is no possible way to confuse these two actions. There's a reason a wheel is attached to the gear lever.

The other day I was eating dinner while chatting with my partner. I finished eating and needed to pee and throw away the fast food container. I walked straight to the bathroom, raised the toilet lid and threw the fast food container right into the toilet. Weird mistakes can happen. My partner got a good laugh out of it

Yep, I’ve taken clean dishes from the dishwasher and put them “away” in the refrigerator.