July 12, 2025, 20:23:00 GMT
permalink Post: 11920812
Question - For those of you with good simulator access.
What - Exactly - are the Flight Deck Effects that would be seen (and in what order?) in the scenario that PM Operated #1 then #2 to cutoff, whilst in flight with APU not running?
e.g. - What screens would blank? for how long? Master Caution? EICAS Messages? Chimes/Aural Alerts?
Intent behind this question is, If PF Does not see the switches operated, what reasonably is the amount of time it would take to look at those switches? Where is the attention initially directed?
What - Exactly - are the Flight Deck Effects that would be seen (and in what order?) in the scenario that PM Operated #1 then #2 to cutoff, whilst in flight with APU not running?
e.g. - What screens would blank? for how long? Master Caution? EICAS Messages? Chimes/Aural Alerts?
Intent behind this question is, If PF Does not see the switches operated, what reasonably is the amount of time it would take to look at those switches? Where is the attention initially directed?
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.
While I doubt the PF would be actively monitoring EICAS during TO, with the sudden audio change to the engine noise as well as the sudden loss of acceleration, I'd expect him to take a quick look at EICAS to see what the (
) the engines are doing. Plus, if the PF was in the right seat and his PFD blanked - I'd expect him to look across to see what's on either the standby or the left seat PFC, and perhaps EICAS.
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July 12, 2025, 20:28:00 GMT
permalink Post: 11920815
They don't have to be positively lifted if the detent rounded out due to wear or if the switch installed was one that the SAIB referenced with the locking feature disengaged. I can't discern a raised boss on the body of the left switch in Fig.13, page 10 of the AAIB report. I assume those switches have some internal over center locking mechanism also besides the spring on the lever that would not be needed if there was no detent. I do remember writing up a 767 switch a long time ago when the Captain noticed the detent was worn and he could shut down without lifting.
On the other hand pilots deciding to end their lives in a spectacular fashion is not inconceivable. In fact over the last 25 years it may be the single most numerous reason for a catastrophic loss of a transport category aircraft operated at a major airline.
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July 12, 2025, 20:34:00 GMT
permalink Post: 11920817
The accident report indicates that the aircraft had a STAB master caution warning on the previous sector. A maintenance action took place during the turnaround in AMD before the accident flight.
Noting that the two guarded stab cutoff switches are directly adjacent to the two guardedfuel run/cutoff switches at the base of the throttle quadrant ,
Noting that the two guarded stab cutoff switches are directly adjacent to the two guardedfuel run/cutoff switches at the base of the throttle quadrant ,
Since some posters seem focused on the theory that the fuel control switches didn't move - just the electric output did (and as I posted earlier, the FDR only knows electrical states, there is literally no other way for the FDR to monitor the switch position).
So I did a little thought experiment. Uncommanded engine shutdowns (for all causes) are already rare - a 10-6 event. Now, during my 40 year career, I can't remember ever encountering a case where the fuel shutoff was commanded without a corresponding movement of the fuel switch. However in this industry it's a good idea to 'never say never', so let's assume it's happened. It would take something like a hot short to cause it to happen ( moving the voltage from RUN to CUTOFF ) since an open circuit will simply leave the valves where they were. That would put its probability way out there - something like 10-8/hr.
So I did a little thought experiment. Uncommanded engine shutdowns (for all causes) are already rare - a 10-6 event. Now, during my 40 year career, I can't remember ever encountering a case where the fuel shutoff was commanded without a corresponding movement of the fuel switch. However in this industry it's a good idea to 'never say never', so let's assume it's happened. It would take something like a hot short to cause it to happen ( moving the voltage from RUN to CUTOFF ) since an open circuit will simply leave the valves where they were. That would put its probability way out there - something like 10-8/hr.
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
The other pilot responded that he did not do so
I would suggest starting with the maintenence engineer/crew who found 'no fault' after the STAB master caution was investigated immediately prior to this tragic flight. It would not be the first time that 'maintenance' caused an incident...
Also, I urge you all to consider how many accidents have been blamed on 'pilot error' (how convenient when billion-dollar companies are at risk) only for further information to come to light that then exonerates the pilots (these stories don't usually make the front page).
Try to stay open-minded folks. The investigation has a very long way to go.
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July 12, 2025, 20:49:00 GMT
permalink Post: 11920823
(The above posted as neither mod nor admin, to be clear).
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July 12, 2025, 21:17:00 GMT
permalink Post: 11920838
I believe the *inspection* was not conducted, and whether there was a fault with the configuration of the switch on the accident aircraft is not answered in the report.
If pilots were able to move this aircraft's cutoff toggles without lifting them, it seems that might have been reported at some point during its service. But then again, maybe the difference in operation between a correctly configured switch (requires lift to toggle) and incorrectly configured one (does not require lift, but lifting it still works as expected) is not noticeable.
I'd be curious to know if India Air has (finally) inspected these switches in their fleet since the accident.
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July 12, 2025, 21:20:00 GMT
permalink Post: 11920839
It is worth remembering that each switch has 4 poles. Think of a pole as a section of the switch. Each section controls a different function - reporting switch position to FDR, fuel cut off and so on. The chances of anything other than real physical switch movement (whether it be spilt liquid, wiring damage, loose canon plug or whatever) changing the status of all 4 sections is impossibly small. Then you have two switches.
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July 12, 2025, 21:20:00 GMT
permalink Post: 11920840
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.
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.
It’s also the norm for everyone operating the switches to give them a tug to insure they are in the detents.
It’s simply inconceivable that both switches failed in exactly the same way at almost exactly the same time and no pilot who flew the aircraft in the last year or so noticed the issues.
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".
Add to that the CVR statement and it’s beyond inconceivable.
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.
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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.
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.
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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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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.
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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.
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.
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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."
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July 12, 2025, 21:39:00 GMT
permalink Post: 11920855
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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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July 12, 2025, 21:43:00 GMT
permalink Post: 11920858
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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.
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.
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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.
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.
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July 12, 2025, 21:50:00 GMT
permalink Post: 11920866
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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.
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 .
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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.
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 .
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