Preliminary report into Air India crash released • Hacker News Board

Re: Preliminary report into Air India crash released

#921

Post by Emdeha2357 » Thu, Jul 17, 2025, 8:53 AM UTC

throwaway48476 wrote: post #804

blincoln wrote: post #712

Earlier quoted context omitted.

This. There are no flip-covers on the switches in any of the photos I've seen. Additionally, it looks like the side guards are only on the left and right sides of the pair of cutoff switches, not in-between the two switches. So if one bumped one switch, seems like it would be very easy to bump them both.

There's a metal nib on the switch and switch housing preventing it from being bumped. There's also a spring holding it down so it can't bounce up. The distance and required force makes switching them at the same time impossible, thus the 1 second difference. This was absolutely an intentional act.

Lookit the damn(ing) pictures:

https://www.xuefeiji.org/public/uploads/weixin_mpimgs/e3/e36...

One can easily switch them with two fingers at the same time. I tried (with similar switches.): Works. If the locking mechanism fails, even unintentionally. Getting loose, wristworn jewlery snatched and then pull: Works.

My question to Boeing is: Why did you cover the neighbouring (stabilizer cut-off, IIRC) switches with red springloaded flip-covers, but not the fuel cut-off switches?

Re: Preliminary report into Air India crash released

#922

Post by Emdeha2357 » Fri, Jul 18, 2025, 2:23 PM UTC

Emdeha2357 wrote: post #916

shoghicp wrote: post #24

Earlier quoted context omitted.

The affected table includes these models as well: 787-8, -9, and -10

Yes, the S.A.I.B. was about the switch, which is used in many airplanes, and _should_ be checked and replaced. But they didn't. Because it wasn't mandatory. So my guess is those 50-70€ per switch were too expensive for the airline? They reported that they replaced the whole middle console twice, so I cannot accept the 'it's pricey' or 'it's non-mandantory' as an excuse. Hackers gona hack, so I'd like to get my hands…

Correction, I quoted the wrong price: Honeywell's 4TL837-3D, which is the switch in the 787s according to the SAIB "EASA_SIB_NM-18-33_1-1.pdf", costs about 1300€. MIL-spec &c. certifications are costly. Still cheap enough to not risk killing hundreds of people with the flick of a wrist. Sorry about that.

Re: Preliminary report into Air India crash released

#923

Post by pertymcpert » Fri, Jul 25, 2025, 3:13 PM UTC

belter wrote: post #881

pertymcpert wrote: post #874

Earlier quoted context omitted.

That doesn't make sense. If a pilot wanted to deliberately cut off the engine there's no reason they couldn't do at that time. The time difference between the switches being one second shows it was more likely to be deliberate, not less. An accidental hit would result in both happening at the same time, not with a time delay.

The two switches changed in sequence, but within the same second and at max speed. Dont think a human can have such a timing. If you look at the timing it looks more and more like electronical or software triggers. Another possibility is a foreign object like a personal item sliding back during acceleration. I looked at both pilots background, and unless a story of medical depression on the part of the captain emerge…

FAA just announced they examined the switched and found no mechanical issues. The switches are not software controlled.

Seems like the evidence is starting to become fairly one sided…

Re: Preliminary report into Air India crash released

#924

Post by belter » Sun, Jul 27, 2025, 3:10 PM UTC

pertymcpert wrote: post #923

belter wrote: post #881

Earlier quoted context omitted.

The two switches changed in sequence, but within the same second and at max speed. Dont think a human can have such a timing. If you look at the timing it looks more and more like electronical or software triggers. Another possibility is a foreign object like a personal item sliding back during acceleration. I looked at both pilots background, and unless a story of medical depression on the part of the captain emerge…

FAA just announced they examined the switched and found no mechanical issues. The switches are not software controlled. Seems like the evidence is starting to become fairly one sided…

I agree the evidence points to the Captain, but the report did not provide the full text of the pilots interaction. The timestamps shows they were cut, one after the other, but within the same second as max vspeed. Doubt humans can have that precision.

>> The switches are not software controlled.

That is what unethical people, like Captain Steeeve - Who changed his "accident clear cause" story four times since the accident - keep saying.

But on the 787, fuel switches are part of the electronic cockpit interface and toggling one sends a command via AIMS to the Engine Interface Unit, then over AFDX to the FADEC. The FADEC actuates the spar and engine fuel shutoff valves who are both electrically controlled with no mechanical linkage.

The switch itself doesn’t cut fuel, it initiates a command interpreted and executed by software. Additionally, software logic can override or block the command based on conditions like fire, overspeed, or sensor faults so its software-controlled end-to-end.

A faulty sensor could trigger even if so far evidence points to the Captain.

"Understanding the Boeing 787 Fuel Control Switch: Function, Operation, and Safety Mechanisms" - https://aeropeep.com/boeing-787-fuel-control-switch-explaine...

"How do the fuel cutoff switches on the Boeing 787 work?" - https://aviation.stackexchange.com/questions/110938/how-do-t...

"Full Authority Digital Engine Control (FADEC)" - https://skybrary.aero/articles/full-authority-digital-engine...

"Full authority digital engine controls have no form of manual override available, placing full authority over the operating parameters of the engine in the hands of the computer.

- If a total FADEC failure occurs, the engine fails.

- Upon total FADEC failure, pilots have no manual controls for engine restart, throttle, or other functions."