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| X-37
July 12, 2025, 21:23:00 GMT permalink Post: 11920843 |
What can be gleaned?
The fuel control switches were moved to cutoff…..or the signal said that they were, the result being the same. Why is the subject of speculation. The CVR transcript has not been fully released. The World Wide 787 fleet has not been grounded. GE are not under suspicion. Crew actions are the likely cause. |
| skwdenyer
July 12, 2025, 21:28:00 GMT permalink Post: 11920844 |
I think the question is *how* fuel switches were accidentally turned off by flight crew, given what\x92s said about their protections?
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| Pilot DAR
July 12, 2025, 21:28:00 GMT permalink Post: 11920846 |
if you raise it up (to change its position) and you turn it slightly clockwise or counterclockwise before releasing it, it will operate normally, but the detents are now "crossing" the lock tab, and this one doesn't prevent a move-it-without-raising-it-first action.
If there were a fault with the locking feature of one of the toggle barrels, this would now be evidence on the initial report, as those parts can be seen to have survived in the photo in the report. |
| nachtmusak
July 12, 2025, 21:31:00 GMT permalink Post: 11920849 |
First, 10 seconds is not a long time. Second, I don't know where you are getting the idea that there was a 10 second gap between the pilots noticing or asking 'why did you cut off' and the switches being reset, because the report doesn't give a timestamp for either exclamation from the pilots. It may well have only been a couple of seconds between them noticing and resetting them, the report simply doesn't give that detail.
The truth will be in what was said after 'I didnt', but that's conspicuously absent from the report. Of course deliberate pilot sabotage has occurred in the past, nobody is disputing that. But personally I'm aware of far more cases of pilot mistakes without malice as the root cause of an accident than of all the confirmed and possible cases of sabotage put together, and I'm sure that there are even more cases of the former that I've never heard about (and I don't mean pilot error in general, I'm referring to things like e.g. taking off with an improper configuration). I think people are not actually thinking through how the situation would play out IF it was an honest mistake. Ten seconds is no time at all for either pilot to: - notice the degrading performance (and/or warnings) - scan the instruments and controls for the problem - see (on their display and confirm on the pedestal) that fuel has been cut off - ask the other pilot why they did that (because neither pilot would believe they were the one who did so - that is how action slips work) - get a response that they did not (again, see above) - snap out of confusion and actually do something about the situation Pilots have reacted with far less alacrity in plenty of accidents (even in cases where the day was ultimately saved) and it was not my impression that the aviation industry accused them of criminal intent for it. Surely there is a middle ground between robotic hyper-competence and literal murder? Don't get me wrong, there is a solid chance that it turns out to have been the deliberate murder of hundreds of people. But to me at least it seems extremely uncharitable to confidently declare that that's what happened off a very loose timeline, or to paint people who are considering the possibility of a mistake as just hiding from the truth. |
| remi
July 12, 2025, 21:37:00 GMT permalink Post: 11920852 |
Earlier today I watched Mentour Pilot's YouTube discussion, one of the things Petter said was "Brain fart of the century" regarding the erroneous selection of cut-off 3 seconds after leaving the ground. Somewhere else I saw this sort of thing described as a "Car keys put in the fridge" event.
I found my cellphone in a fridge once but someone else had put it in there "by mistake." |
| DaveReidUK
July 12, 2025, 21:39:00 GMT permalink Post: 11920855 |
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| Engineless
July 12, 2025, 21:42:00 GMT permalink Post: 11920857 |
Like I said,
if you take the preliminary report version of cockpit dialog at face value
, then if the fuel cutoff toggles were never physically turned off maybe they were not physically turned back on. Immediately prior to this flight the pilots reported a STAB master caution, which was investigated but 'no fault' was found. Intermittent electrical fault? Software/logic problem? Stranger things have happened. At least one maintenance engineer would have been in the cockpit immediately prior to this flight. The actions taken by this person(s) should also be part of the investigation.
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| KSINGH
July 12, 2025, 21:43:00 GMT permalink Post: 11920858 |
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| Sailvi767
July 12, 2025, 21:43:00 GMT permalink Post: 11920859 |
I beg to differ: not from a pilot's point of view who didn't read the bulletin. Please see below about the recommended "tug".
Not a pilot, but electronics engineer here: I finally understood what's wrong with the "defective" switches: on such a switch, if you raise it up (to change its position) and you turn it slightly clockwise or counterclockwise before releasing it, it will operate normally, but the detents are now "crossing" the lock tab, and this one doesn't prevent a move-it-without-raising-it-first action anymore. As far as I can tell from the position of the switches, you have to extend your arm sideways and put some effort in your wrist to activate these switches: chances are that such a movement results in some amount of rotation. Agreed, but this "test" won't tell you if the detents are aligned or misaligned with the lock tab. If both switches are "defective" ones (remember, that doesn't mean they don't do their job, only that some specific action may put them in a state where protection against unwanted action is lost), the same action from the same pilot may well put both switches in the dangerous configuration. By the way, I find that the "check" recommended in the bulletin for a switch suspected from being "defective" is incredibly misleading. It will possibly detect a switch where the cap has already been turned, resulting in a misalignment of the lock tab with the detents, but it won't detect a switch waiting for a turn to put it in the dangerous configuration. The "check" should be "pull on the cap to raise it, try to turn it clockwise or counterclockwise while raised: if it can be turned, it's defective". On the contrary, according to the above scenario, anything interacting with the switches (which are close to each other) can move them unexpectedly (the "iPhone falling" case), and the CVR statement would reflect the surprise of a pilot who actually didn't do anything wrong. May I add that I consider the probability of such a scenario as very very thin, but I wanted to emphasize the fact that we must keep our minds open, instead of jumping to conclusions too early. |
| PC767
July 12, 2025, 21:47:00 GMT permalink Post: 11920865 |
Ladies and Gentlemen
The situation is simply that a human hand moved the fuel switches for reasons unknown. I clung on to the very thin chance that the reason could have been electrical with words such as 'transition', but tdracer's last post extinguished that slim posibility. From day one I have assumed the loss of thrust on both engines and that the only logical explanation could be fuel cut off switches. I've been a pilot for over 35yrs, 12 of which as a paid professional and around airlines in my earlier iteration as cabin crew. Book ending my aviation career I've been in law, as an investigator and now examininer of facts. There is a strong possibility that it will never be established why the switches were moved. My community/previous community will take the liability for this incident, I'd wager something or other on that. If there is ambiguity or a dearth of evidence to be challenged, the easiest target will be the pilots. The reputations of Boeing and Air India will be saved. At this time there is very little technical detail to be discussed on what happened and how it happened. Until either a substantive leak, a further report or the final report is out, I'm out of the thread. I'd suggest many others have the same patience. |
| Engineless
July 12, 2025, 21:50:00 GMT permalink Post: 11920866 |
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| mh370rip
July 12, 2025, 21:55:00 GMT permalink Post: 11920870 |
A query, the FO was pilot flying and the Captain was pilot monitoring. Is it SOP that pilot flying sits in the LHS at takeoff? As I understand it the situation on power failure is that the battery backup will keep the displays alive until the APU comes online but only on the LHS. Trying to maintain best gliding performance and look for best landing site without any instruments to show speed or attitude would be more difficult. Captain taking over and swapping roles at 200 feet mid crisis is disruptive. Tdracer has certainly explained that separation of cabling runs etc would have it very improbable that a single cable fault or short would impact both engines simultaneously in the same way. The CVR data is derived from local sensors with a dedicated battery backup, however all the FDR data and the fuel shut off commands are electrical signals which ultimately have a common source in the aircraft power buses. A water ingress into the EE bay at rotate which momentarily shorted all the low voltage buses to higher AC voltage is unlikely but is it unlikely to the same extent. |
| golfyankeesierra
July 12, 2025, 22:11:00 GMT permalink Post: 11920880 |
No simulator access, but I do know this much:
One EICAS and one PFD is on the battery (most likely the left seat PFD) - they might momentarily flicker but will not 'blank'. You get an EICAS message when you set the fuel switch to CUTOFF - something like "ENGINE X CUTOFF" (not sure of the 787 wording, but it would be something to that effect. And that would explain the weird (at least to me) question of the pilot to the other one “why did you do that” because normally, every time you see the message SHUTDOWN it is always a result of crew action (and that is quite often as you do that about every sim ride). Last edited by golfyankeesierra; 12th July 2025 at 23:10 . |
| AK1969
July 12, 2025, 22:25:00 GMT permalink Post: 11920886 |
1 second delay
Again, you can not conclude that from the report.
Different inputs are sampled at different rates. Some very basic info here: It's highly likely switch positions are only sampled at 1Hz, and not at 100 Hz. For engine parameters you'll likely want a higher sample rate, as the whole engine could go from perfectly fine to exploded in less than a second. If you had something like: 08:08:42.96 UTC: cut off switch 1 08:08:43.01 UTC: cut off switch 2 It would likely be recorded as: 08:08:42 UTC: cut off switch 1 08:08:43 UTC: cut off switch 2 Leading you to believe there was one second between these 2 actions, whereas it was actually only 50ms. Last edited by AK1969; 13th July 2025 at 00:41 . |
| sorvad
July 12, 2025, 22:28:00 GMT permalink Post: 11920888 |
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| skyrangerpro
July 12, 2025, 22:46:00 GMT permalink Post: 11920900 |
It seems to me that there must have been further dialogue after the bland "I didn't". To have nothing reported after that two-line exchange, until the MAYDAY at 08:09:05, is a highly suspect omission from the interim report. In a two-crew cockpit, facing a sudden dual engine rollback just after rotation, I find it very hard to believe that this two-line exchange was the only interaction captured.
Although published a little later than expected, it has now narrowed the speculator's focus from the wilder theories to the fuel switches. Air India is not grounded, Boeing engines are not grounded and there are no recommended actions to engine operators and manufacturers. Although a full verbatim transcript of the CVR could have been published, or even the recording itself, a decision has been made by the investigators not to do so. All we have is two bland paraphrases 'One of the pilots is heard asking the other why did he cutoff' (not even gramatically correct). 'The other pilot responded that he did not do so'. Sometimes reports are more about what is not in them rather than was is in them. It seems to me that the missing sections from the recording which would have revealed exact voice timings, language, tone, inflection and urgency which would have answered a lot of the questions on here have been deliberately withheld either temporarily or permanently. It is for the reader to infer why that might be. The investigators know much more but have chosen not to publicise it. I suspect they have more pieces of the jigsaw than we can see but probably not the full picture yet. Last edited by T28B; 12th July 2025 at 23:06 . Reason: Formatting for ease of reading and pulling out key points |
| LTC8K6
July 12, 2025, 22:55:00 GMT permalink Post: 11920905 |
I have not seen this question asked anywhere and I'm a software engineer (non-aviation), so felt I had to ask it:
Do these solid-looking mechanical fuel switches really act directly upon the fuel system or are they routed via the control system as logic (0/1) signals? It would certainly save a lot of copper and looming time to convert their output into a logic signal before it leaves the cockpit... If the former, ignore all that follows, as it is wrong. If the latter, a control software glitch or electrical noise/short could cause the fuel switches to appear to the control system as being briefly off, while the pilots see the physical switches are still in the on position. Even if such a noisy electrical signal rapidly reverted to correctly indicating fuel-switch on-state after even a few milliseconds, any control system might well have embarked upon a relatively slow relight/startup/engine-protection procedure. In such a scenario, the pilot who first noticed the engines spinning down would query it, while the other pilot would look at the physical switches and see that they were (still) on, and initially be non-plussed by the question. Need to ask the question now satisfied. Andy With that info, your scenario seems very unlikely. |
| verticallimit
July 12, 2025, 22:59:00 GMT permalink Post: 11920907 |
Fire extinguisher handles same function??
Just a thought \x97 the fire extinguisher handles perform the same function as the fuel cut-off.
Could there have been a strap /booklet or something else that accidentally got under the fire handles and activated them when one of the pilots pulled on the item? The fire handles are not particularly well protected against something getting underneath them Is there any information on whether the fuel cutoff switches and fire handles register as separate events on the flight data recorder, or if both are logged under a common indication, such as 'fuel switch cut off'? |
| Mrshed
July 12, 2025, 23:05:00 GMT permalink Post: 11920909 |
If it resulted in an eicas message, then the confused conversation, leading to (several) cycling attempts to reset them successfully to RUN, those 10 seconds later doesn\x92t sound unreasonable at all to me.
Not been in that situation, obviously, but I have certainly been in stressed situations where somewhere, someone (or something) pressed the wrong button, and I need to find out which one. 10 seconds is really not a long time if it is unexpected. It is very short. Please also remember: -We have no idea of exactly what was said. Whether the conversation referred to a error message, engines spooling down or physical switch movement/position. Throw in possible translation inaccuracies, and we can conclude even less from the information about the conversation, or what the level of clarity or confusion were. -There is up to 2 seconds of margin of error in the time code of events because of the (speculated) sampling rate of 1Hz. I'm talking about an electrical failure (for example a short), which is already implausibly affecting both (independent) circuits, causing an issue in a circuit that as I understand it fails open anyway, then resolving itself to become functional again - incidentally in roughly the same time frame that a pilot would notice an issue and seek to correct. This doesn't require knowledge of the cockpit conversation or judgement on speed (or otherwise) of the recovery. It's purely that an already incredibly unlikely scenario (electrical failure) becomes even more unlikely with the spontaneous *and synchronised, but not perfectly so* removal of the fault state of whatever this failure was. *Edit* Given my previous post has been removed it would appear that the mods also misread this to do with timing of *pilots response*, which I find a little odd as it was in response to a comment about electrical failure... To be honest at this point for me we are immediately hamster wheeling again, and this time because any commentary around either electrical circuit issues (astronomical odds) or accidental device triggering cut off (no evidence nor can there be right now) are speculation in nature and have to be. Equally, while the obvious culprit is hands on the switches, any comments about why again are speculation and have to be. There's nothing more anyone can get to on this one until further CVR data is released in my view. Bowing out. Last edited by Mrshed; 12th July 2025 at 23:18 . |
| MikeSnow
July 12, 2025, 23:06:00 GMT permalink Post: 11920911 |
Tdracer has certainly explained that separation of cabling runs etc would have it very improbable that a single cable fault or short would impact both engines simultaneously in the same way. The CVR data is derived from local sensors with a dedicated battery backup, however all the FDR data and the fuel shut off commands are electrical signals which ultimately have a common source in the aircraft power buses. A water ingress into the EE bay at rotate which momentarily shorted all the low voltage buses to higher AC voltage is unlikely but is it unlikely to the same extent.
What bothers me is that message about the stab cutoff switches on the previous flight. It's a bit of a strange coincidence, since those switches are quite close to the fuel switches. I'm thinking that maybe some liquid could have been spilled during the previous flight over the area of the fuel switches and stab cutoff switches. Perhaps it initially affected just the stab switches. Then, during the accident flight, the acceleration and/or the rotation might have caused residual liquid to move and cause some issue for both fuel switches. Then, as the acceleration stopped after the loss of thrust and the aircraft stopped climbing, maybe the liquid moved again and the fuel switches recovered. But I admit this seems very unlikely. |
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