[HN Gopher] Preliminary report into Air India crash released
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Preliminary report into Air India crash released
Report:
https://aaib.gov.in/What%27s%20New%20Assets/Preliminary%20Re...
Author : cjr
Score : 40 points
Date : 2025-07-11 20:23 UTC (2 hours ago)
(HTM) web link (www.bbc.co.uk)
(TXT) w3m dump (www.bbc.co.uk)
| rawgabbit wrote:
| Quote: As we just reported, the report says
| that according to data from the flight recorder both the fuel
| control switches, which are normally used to switch the engines
| on or off when on the ground, were moved from the run to the
| cutoff position shortly after takeoff. This caused both engines
| to lose thrust.
|
| The preliminary report suggests this is pilot error.
| lazharichir wrote:
| From my (limited) understanding you cannot really switch these
| off inadvertently as they require a couple of actions in order
| to be switched off. So it would mean one of the pilots switched
| these off (and they were a few seconds later switched on again
| but it was too late).
|
| But there was audio, too, and one pilot asked the other "why
| did you switch these off" and the second one said "I didn't".
|
| Was there are third one in the jump seat?
| rawgabbit wrote:
| The report only said the copilot was flying and the pilot was
| monitoring.
| fracus wrote:
| Sounds likely that one of them was sabotaging the flight.
| zihotki wrote:
| It does not suggest that. It only says they were turned off and
| no other conclusion given.
| mallets wrote:
| Well, shit. Suicidal?
|
| And this can't possibly be all the audio if the other pilot
| noticed the switch position, I would expect a lot more cussing
| and struggle.
|
| So they didn't notice the switch position? The switch was in the
| right position but not really? Is this a rarely used switch that
| one might not look at (or know where to look) during regular use?
|
| 10 seconds between OFF and ON.
| chupchap wrote:
| From what I've read, it comes on the display as a warning
| rwmj wrote:
| The India AAIB website (https://aaib.gov.in/) is not responding
| ... For anyone who read the report, was there information about
| the age & experience of the pilots?
| mtmail wrote:
| 56 years old, 15638 hours (8596 on this type) and 32 years old,
| 3403 hours (1128 on this type). Page 11 of the PDF report.
| foldr wrote:
| Report PDF here:
| https://aaib.gov.in/What's%20New%20Assets/Preliminary%20Repo...
| belter wrote:
| Not accessible. Have they heard about S3 ?
| foldr wrote:
| It loads for me, so I think the link will be useful for some
| people at least.
| shoghicp wrote:
| mirror
| https://web.archive.org/web/20250711203907/https://aaib.gov....
| d_silin wrote:
| Report page that matters:
| https://x.com/exodusorbitals/status/1943782924576309732
| decimalenough wrote:
| > _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 switches in
| question are also built so they cannot be triggered accidentally,
| they need to be unlocked first by pulling them out.
|
| > _In the cockpit voice recording, one of the pilots is heard
| asking the other why did he cutoff. The other pilot responded
| that he did not do so._
|
| And both pilots deny doing it.
|
| It's difficult to conclude anything other than murder-suicide.
| chupchap wrote:
| Or a mechanical failure
| ceejayoz wrote:
| Both switches, at slightly different times? Seems pretty
| unlikely.
| ceejayoz wrote:
| > 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.
|
| > As per the EAFR, the Engine 1 fuel cutoff switch transitioned
| from CUTOFF to RUN at about 08:08:52 UTC.
|
| Damn. That's pretty quick to diagnose and take action.
|
| Boeing's probably gonna have a big sigh of relief over this
| one.
| alephnerd wrote:
| > 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?
| ummonk wrote:
| You have to pull the switches out (against a spring) to be
| able to move them over a notch and flip them. Not really
| something you can just mistake for another switch or bump
| into by accident.
|
| I'd liken it to turning off the ignition by turning the key
| while driving your car. Possibly something that could happen
| if you're really fatigued, but requires quite a mental lapse.
| joezydeco wrote:
| Report says the switches went to cutoff one second apart
| from each other. Can a human do the physical operation on
| two switches that quickly?
| snypher wrote:
| There's a good photo of them here;
| https://theaircurrent.com/aviation-
| safety/ai171-investigatio...
|
| You can do them both with one hand.
| zihotki wrote:
| Are you completely sure you can considering that they are
| spring loaded and they are like 7-10cm apart judging by
| the size of other controls?
| heisenbit wrote:
| The timing is really curious.
|
| 08:08:35 Vr
|
| 08:08:39 Liftoff
|
| 08:08:42 Engine 1 cut-off
|
| 08:08:42 Engine 2 cut-off
|
| 08:08:47 minimum idel speed reached
|
| ?? One pilot to other: why cut-off. Other: Did not do it
|
| 08:08:52 Engine 1 run
|
| 08:08:52 Engine 2 run
|
| 1 second to switch them both off and then 4 seconds to
| switch them both on. No one admitted to switch them off.
| They are probably going with fine comb over the audio and
| also the remains of the chared switches.
|
| Looks like the engines react very quickly to cut-off so
| it is not clear whether the question about the cut-off is
| prompted by a glance to the switches or the feel of the
| airplane.
|
| The big question is whether the switches were moved or
| something made it seem as if the switches were moved.
| xenadu02 wrote:
| 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 removed it pops up a "60s to shutdown dialog"
| that you can cancel. Even if you accidentally press SHUTDOWN
| it only switches to a 10s countdown with a "CANCEL" button.
|
| They could insert a delay if weight on wheels is off. First
| engine can shutdown when commanded but second engine goes on
| 60s delay with EICAS warning countdown. Or just always insert
| a delay unless the fire handle is pulled.
|
| Still... that has its own set of risks and failure modes to
| consider.
| lazystar wrote:
| 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
| supply or cutoff fuel to the engines. The fuel control switch
| has a locking feature to prevent inadvertent operation that
| could result in unintended switch movement between the fuel
| supply and fuel cutoff positions. In order to move the switch
| from one position to the other under the condition where the
| locking feature is engaged, it is necessary for the pilot to
| lift the switch up while transitioning the switch position. If
| the locking feature is disengaged, the switch can be moved
| between the two positions without lifting the switch during
| transition, and the switch would be exposed to the potential of
| inadvertent operation. Inadvertent operation of the switch
| could result in an unintended consequence, such as an in-flight
| engine shutdown. Boeing informed the FAA that the fuel control
| switch design, including the locking feature, is similar on
| various Boeing airplane models. The table below identifies the
| affected airplane models and related part numbers (P/Ns) of the
| fuel control switch, which is manufactured by Honeywell.
|
| > If the locking feature is disengaged, the switch can be moved
| between the two positions without lifting the switch during
| transition, and the switch would be exposed to the potential of
| inadvertent operation. Inadvertent operation of the switch
| could result in an unintended consequence, such as an in-flight
| engine shutdown
| barbazoo wrote:
| Same manufacturer, Air India 171 was a 787-8 though.
| shoghicp wrote:
| The affected table includes these models as well: 787-8,
| -9, and -10
| barbazoo wrote:
| Thanks for pointing it out.
| ggreer wrote:
| The only affected models were 737s with the 766AT613-3D
| fuel control switch. The bulletin recommended that other
| models be inspected and any defects reported. It's
| unclear if any 787s were discovered to have the issue.
| Also the preliminary report mentions that the switches
| were replaced in 2019 and 2023, after the 2018 bulletin.
| lazystar wrote:
| 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.
| cosmicgadget wrote:
| Cutting fuel just after takeoff leaves almost zero time
| for the other pilot to recover.
| tekla wrote:
| They don't mention the locking mechanism being disabled
| cosmicgadget wrote:
| Is it easy to inadvertantly move both switches in such a
| scenario?
| mdavid626 wrote:
| Well, can you move it back, when accidentally activated?
| joshAg wrote:
| at least one of the pilots did. according to the
| preliminary report, the switches were only in the cutoff
| position for 10 seconds before being switched back to the
| run position and the engines started to spin up again
| sillysaurusx wrote:
| 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 was a mass murder.
| ummonk wrote:
| Yeah and the other pilot flipped the switches back on and one
| of the engines started spooling up but it was too late.
|
| Murder-suicide looks like the likely conclusion, given that
| flipping the cutoff switches requires a very deliberate action.
| That said, it's not entirely impossible that due to stress or
| fatigue the pilot had some kind of mental lapse and post-flight
| muscle memory (of shutting off the engines) kicked in when the
| aircraft lifted off.
| breadwinner wrote:
| > _post-flight muscle memory (of shutting off the engines)
| kicked in_
|
| Possible, and if so it is too early to conclude it was
| murder-suicide.
|
| See also: https://www.thehindu.com/news/national/dgca-
| slaps-80-lakh-fi...
| Jtsummers wrote:
| 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.
| bgwalter wrote:
| 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 days of
| limited storage are over.
| tekla wrote:
| Yes there is.
| ssl232 wrote:
| > EDIT: Why is there no Cockpit Video Recorder? The days of
| limited storage are over.
|
| Pilots unions are dead against it.
| dcreater wrote:
| 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
| cosmicgadget wrote:
| Murder-suicide has happened on a few occasions. How many
| times has your malfunction occurred on an aircraft fuel
| system?
| __turbobrew__ wrote:
| 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.
| pigbearpig wrote:
| There are pictures of them in the report.
| joshAg wrote:
| there's a picture of their condition on page 10 of the report
| bob1029 wrote:
| > The EGT was observed to be rising for both engines indicating
| relight. Engine 1's core deceleration stopped, reversed and
| started to progress to recovery. Engine 2 was able to relight but
| could not arrest core speed deceleration and re-introduced fuel
| repeatedly to increase core speed acceleration and recovery.
|
| I know it's probably not worth the hazmat tradeoff for such a
| rare event, but the F-16 has an EPU powered by hydrazine that can
| spool up in about a second.
| ceejayoz wrote:
| I suspect any civil aviation engineer who goes "let's add
| hydrazine!" to fix problems has a fairly short career, lol.
| ChrisArchitect wrote:
| More discussion: https://news.ycombinator.com/item?id=44536691
| cosmicgadget wrote:
| The report says the co-pilot was flying so it's most likely the
| pilot cut the fuel?
| sillysaurusx wrote:
| Correct. Which means it's the older of the two.
| sillysaurusx wrote:
| Since everyone seems to be dancing around the issue, here are the
| facts as they stand:
|
| - There is no chance that the fuel switches were turned off by
| accident.
|
| - They were off for about five seconds. One pilot asked "why did
| you turn them off?" and the other said "I didn't."
|
| - They were flipped back on five seconds later. So, ten seconds
| of off time total.
|
| - It takes a long time for jet engines to spool up; it's not like
| a propeller, where the thrust comes back instantly. Ten seconds
| at 600ft was a death sentence.
|
| - This was not suicide, or murder-suicide; it was one of the most
| horrific mass murder in history, in which the guy that did it
| happened to lose his life in the process.
|
| So the big question is, who was flying? The report doesn't say.
|
| In the cockpit, one person is designated "pilot flying" and the
| other "pilot monitoring." During takeoff, the pilot flying is
| completely focused on takeoff. This would be the perfect
| opportunity to betray your colleague as the pilot monitoring.
|
| - The younger of the two was pilot flying. That means the older
| person was pilot monitoring.
|
| - This person was also a few flights away from retirement.
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(page generated 2025-07-11 23:00 UTC)