Posts about: "V1" [Posts: 122 Pages: 7]

Alty7x7
July 13, 2025, 00:24:00 GMT
permalink
Post: 11920958
Takeoff thrust loss

Originally Posted by Mrshed
On a slight tangent, I think the saddest thing about the report is learning that the plane was starting to recover.

how far off avoiding this do we think they were? 5-10 seconds?
Takeoff performance assumes a single engine loss - 50% of thrust for a twin - at V1, assuming V1 occurred at the correct time and place on the runway (before that, RTO). It is really an integral or area under the curve issue.

With about 10 seconds between to-Cutoff and back-to-Run, it.is hard to see recovery with any terrain or obstacles present. Perhaps, assuming accidental Cutoff, they were restored within a second or two, the Quick Relight could have restored thrust rapidly as the engines were still spooling down - then it is a matter of the built-in margins in the takeoff performance. But the report said the engines both were sub-idle when the Quick Relight logic would have reactivated with the restoration to Run.

I doubt it was close - up to 10 seconds with 100% thrust loss. It could easily be evaluated in a Simulator, but not sure it matters now.
MaybeItIs
July 13, 2025, 04:15:00 GMT
permalink
Post: 11921010
Originally Posted by slats11
You want these switches within reach of both pilots, in a position where hands are not constantly passing over them, able to be actioned quickly, to be internally guarded (= require 2 distinct actions to move) as well as externally protected (side guards). It also seems logical to have them near the thrust levers.

Boeing have achieved all this.

It feels like it would be an error to try and redesign these switches in light of this incident. The switches operated as they were commanded.
Sorry, I have to seriously disagree, in the nicest possible way, I hope.

The switches must be accessible - Yes
They are where hands regularly pass over them - a No. As I see it, a certain expression regarding the back end of a male dog comes to mind!
Able to be actioned quickly - arguably, currently, it's much too quickly, IMHO.
Guarded - when it comes to Cerebellum (Yes, please search that word in this thread)-generated actions, that makes zero difference. When the Cerebellum has been trained and learned, it will repeat the most complex sequences you can think of - without you having to think of them. That's the REAL problem that needs to be solved.
Logical - Yes, but really No! Putting them close together can more easily result in the wrong action at times of high stress, confusion, fear, danger, urgency, whatever.

I say they need a major, i.e. Total redesign.

But one of the big problems is that these two switches are used at least a couple of times on every flight. So, they are true Cerebellum Fodder.

However, here's one suggestion. The modern plane is full of sensors, interlocks and logic devices. Use them a bit smarter, I say!

When the plane is on the ground, allow the Fuel Switches to be turned On and Off without debate. But using Air/Ground and /(or?) WoW, when the plane is in the air, the process must be made markedly different. At the very LEAST, make them properly guarded, so a flap must be lifted to action them. And as soon as the flap gets lifted in flight, a very loud alarm and maybe a light is triggered. Then, everybody knows, no need for guessing. Until you or your fellow pilot presses the Confirm button somewhere nearby, the switches can't be moved - or are disabled, or something.

If you don't regularly use this procedure, the Cerebellum won't be so likely to Run It Automatically in a panicked rush. The different process from what you did just at the start of the flight will trip up the cerebellum somewhat, and trigger the Higher Brain to start thinking...: "What? Is this correct?"

How about this?

Subsequent thoughts: The Confirm button would only remain live for a short period, say 3 seconds, during which time, you can operate the switch. Then it resets.
Another idea: Leave the Fuel Cutoff switches right where they are, as they are. But, when in Flight, totally disable them. Alarm if moved. Put the In-Flight Shutoff switches in the overhead panel, with the same kind of aural/visual Confirmation-required warning system permanently operative.

P.P.S. That may not be enough, maybe there needs to be a Takeoff speed transition added - i.e. Before Rotate. Maybe just after V1?

Last edited by MaybeItIs; 13th July 2025 at 04:48 . Reason: add the subs.
Mrshed
July 13, 2025, 10:13:00 GMT
permalink
Post: 11921202


Not sure if this is helpful for anyone or not but I thought a visual view of the timeline of events might be useful, in seconds since V1.

I've assumed 1Hz for the switch sampling rate and >1Hz for everything else (could be wrong) to give windows for the switch state changes.

I've also added in the ADS-B relevant data, although made no attempt to work out whether these timestamps are synchronised or not, so take them as you will.

I have assumed the cutoff is in chronological order from the report, albeit I have ignored the RAT supply timestamp in terms of chronology from the CVR recording, as that statement in the report at that time may just be due to contextual nature of the statement, rather than it happening prior to the RAT power supply. This gives a window for potentially when that statement was made (assuming also that it was made prior to reversing cutoff).

Don't think it neccessarily adds anything for me, other than:

- Would we expect ADS-B data to stop on engine transition to run? Note that ADS-B data was received between 08:08:43 and 08:08:51, so apparently only received in the time window that the switches were in "cutoff"
- The window between the switches being shut off and moved to run could be as short as 8 seconds, and the window between engine 1 and engine 2 being moved to run could be as short as 2 seconds
- The statement on the CVR could be a wide range of timepoints.

The ADS-B data is in my view odd, albeit this might be my lack of understanding. Yes, not synchronised, but unless the timestamps are way out (like 10 seconds out, and given the timestamp of max altitude, this feels incredibly unlikely), ADS-B data was transmitted without issue during phase 2 (both engines off, no RAT), and phase 3 (both engines off, RAT)...but NOT phase 4 (both engines firing back up, presumably still with RAT?). Bear in mind that phase 4 is almost half of the short flight. Also it would appear no data during phase 1 (both engines on), including during takeoff, despite receiving data during taxi?

*EDIT* - having looked into some other historical ADS-B data for this airport, albeit a bit cursory, it definitely appears that the lack of data in "phase 1" that I've outlined above is solely a coverage issue, with no other flights I can see having coverage in that area either. It's harder to determine the "phase 4" element as obviously no airplanes in a normal mode are in that geographical region at the altitude in question, but it does appear to be a reasonably safe bet that the missing datapoints are coverage related.

Last edited by Mrshed; 13th July 2025 at 11:47 .
unworry
July 13, 2025, 10:23:00 GMT
permalink
Post: 11921207
Originally Posted by Mrshed


Not sure if this is helpful for anyone or not but I thought a visual view of the timeline of events might be useful, in seconds since V1.

I've assumed 1Hz for the switch sampling rate and >1Hz for everything else (could be wrong) to give windows for the switch state changes.

I've also added in the ADS-B relevant data, although made no attempt to work out whether these timestamps are synchronised or not, so take them as you will.

I have assumed the cutoff is in chronological order from the report, albeit I have ignored the RAT supply timestamp in terms of chronology from the CVR recording, as that statement in the report at that time may just be due to contextual nature of the statement, rather than it happening prior to the RAT power supply. This gives a window for potentially when that statement was made (assuming also that it was made prior to reversing cutoff).






Thank you for the diagram. Picture = 1000 words

Really highlights how knowing precisely when the why did you cutoff" question was asked might have provided more clarity and less speculation as to how those fateful seconds played out

And it would have helped to know if Positive rate / Gear Up was called ... and when

Last edited by unworry; 13th July 2025 at 12:19 .
safetypee
July 13, 2025, 11:12:00 GMT
permalink
Post: 11921236
'Normal' Accidents

From the CVR, the switch position was noticed, questioned, and with understanding selected to Run; the crew apparently had a quick understanding of what would be a very surprising situation - startle, mind numbing, thought restricting conditions.

It is reported that P2 was handling; in this case the Captain might guard the thrust levers until V1, moving his hands away, but not onto the control wheel - rearwards, … thence with cuffed sleeve …

A speculative scenario of inadvertent switch operation of 'unguarded' switches.

A combination of most unlikely - unbelievable factors, which came together at that time. Yet such rarities and combinations litter the wreckage of past accidents; and with hindsight they were 'normal'.
Normal SOP for P2 takeoff; errant switches escaped SAID checks - 'normal' for that aircraft.

If the switches were inadvertently moved, the realisation, even subconsciously, might support the apparent quick understanding and action.

… waiting for: a report on the condition of the cutoff switches condition wrt guarded operation …

njc
July 13, 2025, 11:43:00 GMT
permalink
Post: 11921256
Originally Posted by Mrshed
Not sure if this is helpful for anyone or not but I thought a visual view of the timeline of events might be useful, in seconds since V1.
Very helpful, thanks! One recommendation for change: since we don't know what words were used by the pilots, how about using "CVR: query cutoff" rather than "why did you cutoff"?
Originally Posted by Capn Bloggs
@Maybeitis, how about we leave the total redesign of the fuel switch locations and operation (which have been moved billions of times in thousands of aircraft without a hitch) until the final report is out.
These were deliberately moved. It wasn't a brain-fart. Unless the interim report omits crew calls which turn the scenario on it's head.
Most of your comments in the thread are extremely sensible but I take issue with both points you made in this post.

Firstly, you'll have seen plenty of things to disprove the "without a hitch" in this thread alone , and as a professional pilot you'll no doubt know of many others - including switches moved in-flight as a brain-fart , or switches moved by things like falling objects. Waiting for the final report may tell us if it would have made a difference in this case, but the lower tier of the safety pyramid (non-severe outcomes) is definitely already populated with plenty of examples of "hitches".

Secondly, I'm absolutely inclined to agree that the switches were moved deliberately (though perhaps absent-mindedly), but I'm genuinely shocked and baffled that you are already willing to assert that "It wasn't a brain-fart". Perhaps those words were typed in haste and you didn't re-read what you had written? (A brain-fart, in other words.)
Originally Posted by B2N2
You don\x92t \x93flick switches in the Sim\x94 for no apparent reason.
Even Indian sources are now reporting on the possibility of intent.

https://www.ndtv.com/india-news/air-...-probe-8864239
That interview has a series of very poorly judged comments by someone who should certainly know better, and IMHO adds nothing of value. It doesn't even acknowledge the possibility of an action-slip/brain-fart/execution-error as cause, and the interviewee voices his suspicion about a cover-up based on the identities of the speakers of key remarks not being shared at this point. Surreal.
double-oscar
July 13, 2025, 14:45:00 GMT
permalink
Post: 11921364
It would have been useful if more of the CVR data had been released so as to see the crew interaction. Also the language used on what was released seems to refer to a third person.
However, from an operator perspective. Captain PM, FO PF. PF selects TOGA and follows the thrust levers, Captain confirms Thrust Set and replaces FO hands on the Thrust Levers. 80Kt call by PM, acknowledged by PF. Aircraft calls V1, Captain should withdraw hands from Thrust Levers and calls Rotate at Vr. PM is looking for confirmation the aircraft is climbing and calls Positive Rate. PF confirms and calls Gear Up. At this point the PF will be looking through the HUD looking to follow the flight director, the PM would be checking LNAV had engaged and at 400\x92 checking THR REF and VNAV SPD. However, at this point a loss of thrust occurred. So how was this apparent to the PF who would have been looking out with both hands on the control wheel. Reduction in pitch? GPWS call-out? Decreasing N1 on the engine instruments? EICAS ENG SHUTDOWN? What did the PM see? Who called out the situation? Were any actions called for? At some point as the generators went off line all the FO instruments would have blanked. Did the Captain assume control? I don\x92t think I would have been thinking about the Fuel Cut-Off switches at that point, yet they were specifically mentioned which does mean the switches were moved and it wasn\x92t some internal fault.
Hopefully, as the CVR is further analysed some more information will come to light.
Mrshed
July 13, 2025, 15:38:00 GMT
permalink
Post: 11921398
Originally Posted by AfricanSkies
It may equally well be 4.99 seconds.
MrShed will have to redo his drawing.
I think the drawing is correct, you just cant count the window as the total possible elapsed time, rather that its within a 1 second window within that broader window (that in all liklihood spans seconds and doesnt tick over exactly as a second ticks over). There's a difference here between reporting timeliness, which is what we are discussing here, and reporting accuracy - both are factors in the possible actual event window.

Engine 1 transition to RUN, reported at 08:08:52, which is 19 seconds post V1. However, at 1Hz this change could have occurred up to 1 second before, i.e. 18 seconds post V1.
Engine 2 transition reported at 08:08:56, 23 seconds post V1, but same logic, so either 22 seconds post or 23 seconds post.

This does indeed give a maximum window of 4.99 seconds, although this is still approximate as it presumes that both switches are sampled at the same point in time, and it also ignores the fact that a second isnt a discrete point in time, but its close enough.

Note that if both switches arent sampled at the same point in time, which I'd assume they probably aren't, this makes the maximum possible actually 5.98 seconds, and the minimum possible elasped time just 2.02 seconds.

e.g. Engine 1 switch is sampled at the 990th ms per second, hence recording the time as 08:08:52, but this was actually 08:08:52.99, and assume this is when the switch actually changed. Engine 2 samples exactly on the second, but changed 990ms ago. Recorded as 08:08:56, but actually occurred t/f at 08:08:55.01. This makes the difference 2.02.

This assumes the timing is recorded as "within" the second in question, rather than rounding to the nearest second, but I'd strongly presume it does this as its fundamentally how computer clocks work.

Basically, when looking at two 1Hz samples and comparing, you need to add +/- 1.98 seconds to the timestamp differences to give true range. Of course, assuming stochastic sampling and assuming that the events are independent to clocks (i.e. are not triggered by a time event), then on average the most likely difference in time between them by the distribution will be exactly what it says on the tin - i.e. 4 seconds. But other time differences are possible across the distribution.

It should be noted though that under these assumptions, the probability of an actual time difference of <3 seconds reporting as 4 seconds is pretty vanishingly small (less than 0.01%), although the chances then increase significantly. But an actual 4 to 4.5 second time difference only has about 68% chance of being *reported* as a 4 second time difference, so the time deltas here do have only around a two thirds accuracy given the time granularity reported in the report.

Last edited by Mrshed; 13th July 2025 at 16:12 .
Contact Approach
July 13, 2025, 18:03:00 GMT
permalink
Post: 11921494
Originally Posted by double-oscar
It would have been useful if more of the CVR data had been released so as to see the crew interaction. Also the language used on what was released seems to refer to a third person.
However, from an operator perspective. Captain PM, FO PF. PF selects TOGA and follows the thrust levers, Captain confirms Thrust Set and replaces FO hands on the Thrust Levers. 80Kt call by PM, acknowledged by PF. Aircraft calls V1, Captain should withdraw hands from Thrust Levers and calls Rotate at Vr. PM is looking for confirmation the aircraft is climbing and calls Positive Rate. PF confirms and calls Gear Up. At this point the PF will be looking through the HUD looking to follow the flight director, the PM would be checking LNAV had engaged and at 400\x92 checking THR REF and VNAV SPD. However, at this point a loss of thrust occurred. So how was this apparent to the PF who would have been looking out with both hands on the control wheel. Reduction in pitch? GPWS call-out? Decreasing N1 on the engine instruments? EICAS ENG SHUTDOWN? What did the PM see? Who called out the situation? Were any actions called for? At some point as the generators went off line all the FO instruments would have blanked. Did the Captain assume control? I don\x92t think I would have been thinking about the Fuel Cut-Off switches at that point, yet they were specifically mentioned which does mean the switches were moved and it wasn\x92t some internal fault.
Hopefully, as the CVR is further analysed some more information will come to light.
Very good post and just as I expect. The PF is busy, the PM is not. Had the PF moved the switches it would not have taken all that time to get them back into run. Had the PM moved the switches then it will take the PF a few seconds to figure out what on earth is going on.

Interestingly ENG 1 was cut off first\x85
Mrshed
July 13, 2025, 18:39:00 GMT
permalink
Post: 11921522
Originally Posted by andihce
I would like to raise a subject that I don't believe has been discussed here since the Preliminary Report was published, namely what happened to the aircraft's electrical systems as a consequence of the dual engine rollback and thereafter (RAT deployment, partial engine recovery, etc.). Apologies if I've missed posts on this topic here, but I have tried to review all of this thread quickly after previously reading most of it in detail.

As I understand it from previous discussions, without the APU, all electrical power except for that DC power provided by battery to essential systems would have been lost.

With the copilot as PF, would he have lost his instrument displays? If so, possibly additional startle effect and workload for him.

Why did the ADS-B information keep going on for so long? My understanding from previous threads was that loss of ADS-B was considered an indication of loss of electrical power.

What else would be expected with loss of power?

Some general speculation: I find it hard to understand the long delay from what must have been the onset of obvious issues to the time the first engine is set to "RUN". I wonder if much more cockpit dialog intervened, e.g. PF requesting PM to turn the fuel switches back on (since he had his hands full), and eventually operating the switches himself, with the delay and time gap between the two switches being turned to "RUN" being attributable to being preoccupied with flying the aircraft under trying conditions.
These for me are very interesting questions.

There seems to be a period around second 12/13 post V1 where engines are (or should) be likely below idle, but prior to RAT power generation.

Note that the report explicitly states the RAT started providing hydraulic power 5 seconds after engine shutdown commenced. It doesn't reference electrical power. So we don't know whether this was at the same time - others may clarify re: RAT operation.

But either way, it would appear there would be a gap in power (which, incidentally, would tie in with the survivor commentary). But yet ADS data continued.

If in fact there was a momentary loss of power then that would contribute heavily to the startle and "delay" in refiring (although comments here make me think there wasn't really such a delay anyway).

(And incidentally would make what appears to be a really rather valiant attempt to save the aircraft even more impressive)
B2N2
July 13, 2025, 19:06:00 GMT
permalink
Post: 11921541
Originally Posted by Mrshed
These for me are very interesting questions.

There seems to be a period around second 12/13 post V1 where engines are (or should) be likely below idle, but prior to RAT power generation.

Note that the report explicitly states the RAT started providing hydraulic power 5 seconds after engine shutdown commenced. It doesn't reference electrical power. So we don't know whether this was at the same time - others may clarify re: RAT operation.
RAT can provide both hydraulic and electrical but will prioritize hydraulic to the Center Hydraulic System to keep the flight controls working.
If memory serves me right on the 777 the electrical output capacity of the APU is about 8-10 times the output capacity of the RAT.
It will likely be even more on the 787.
fdr
July 14, 2025, 00:33:00 GMT
permalink
Post: 11921803
Originally Posted by tdracer
While this is thread is still deeply into hamster wheel status, there are some valuable inputs being made. I'll try to continue with that...

Thrust lever position post-accident - it takes very little force to move the thrust levers, a little more than one pound-force at the knob. I'd be very surprised if the post impact position was the same as pre-impact (and lever angle is recorded on the FDR, so the investigators know where they were). In short - the post-accident lever position is not meaningful.

Fuel condition switch position detents - if the Indian investigators had any reason to believe that a failed or inoperative detent was a contributing fact, the authorities would have ordered a fleet-wide inspection (especially since it literally takes only seconds to do the inspection - the paperwork would take many times longer than the actual inspection).

Engine restart (i.e. "Quick Windmill Relight"): Even if the igniters were firing, at high power they won't actually spark (the electrical resistance or the air at several hundred psi prevents a spark) - so they won't spark until you get down somewhere near idle if you're close to sea level. Once the engine has dropped below the min idle, it takes a long time for it accelerate back to even an idle condition. At takeoff power, the compressor components get very hot - do a power cut the air coming in the compressor gets heated by the residual heat in the compressor. This in turn limits how fast you can add fuel in the burner without excessively back pressuring the compressor and causing a compressor stall. So it actually takes longer for the engine to accel to idle that it would during a normal (cold engine) start. The 5 seconds to 95% accel requirement referenced earlier is from a stable 'high' idle (we typically call it 'approach idle' since it's automatically selected when landing flaps are selected). Approach idle is ~10% N2 higher than the in-flight minimum idle, so that takes several more seconds. Bottom line, after initiating the Quick Windmill Relight, you're not going to have usable thrust for at least 30 seconds - probably closer to 60 seconds.

For all the complaining about this preliminary report, it actually goes into more detail than is typical.

BTW, my money is still on the 'muscle memory/action slip' or whatever you want to call it. I can easily imagine a scenario along the line of 'why did you turn off the fuel' - 'I didn't - oh wait - oh ...
Well said TDR, the report expressly states that the T/R levers are bent but in the stowed position, so it is quite probable that the thrust lever angle is not as they were in flight pre impact.

The last line, is not a zero possibility, but at present the whole wiring system for the fuel control switches would need to be evaluated for any potential common fault that may be intermittent before I would lean towards the cognitive slip type error. The poor old FO would have both hands on the yoke from V1, irrespective of the company's SOP and so would have been rather unpleasantly surprised by the loss of performance. I think the 10 seconds in this case is remarkably fast observation-orientation-decision-action sequence, and that one engine had already started to recover towards operation is a credit to the design of the engine.

Yomama1999
July 14, 2025, 21:25:00 GMT
permalink
Post: 11922514
It's peripheral vision, it's baked in through millions of years of evolution for us to notice something in the corner of our eye.
It covers 190 degrees from left to right.


Not detail, but broad shapes and movement,
Not color, black and white will do.

Since after V1 there is nothing at the thrust quadrant to obscure anything, anything happening there is easily noticed.

It's because if any of your forefathers/mothers noticed something deadly out of the corner of their eye, they saw it, acted and survived.
DutchRoll
July 14, 2025, 22:12:00 GMT
permalink
Post: 11922547
Originally Posted by LTC8K6
I'm still not clear on something, no surprise there.

If you are the PF and you are just after rotation, and for whatever reason, the fuel control switches transition to "CUTOFF", when and how do you notice this?
Presumably your hands are on the yoke and you are looking very intently out the windshield. So, to me it seems unlikely that you saw whatever happened to the switches, however they moved.

Do you get a warning indication that the switches have moved? If so, then that would be what I needed to know. You got a warning and therefore you looked right at the switches.

If not, do you just notice that you have lost power? If that is the case, where do you look first? I presume it would be at the engine info gauges/displays.

What I'm getting at is what priority is given to looking at the fuel cutoff switches in this situation?
How long until you look at those switches as the possible cause of the engine problems?
Not a B787 pilot but many hours on its wide body predecessors.

It is conceivable that you could notice hand movement around the throttle quadrant in your peripheral vision (noone's hands are on the thrust levers between V1 and shortly after takeoff), however even if you didn't, you'd immediately notice the loss of performance. The instinctive reaction is big loss of performance -> quick glance across at instruments -> why are they winding back? Also if the fuel control switches were moved to cutoff you'd suddenly get EICAS messages saying the engines were shutdown. So there are immediate clues and it's only a minor head movement to see where the fuel control switches are because they're right down there behind the thrust levers. Then the immediate action for a dual engine failure, which would by then likely be obvious with both sets of instruments showing everything winding back, is "fuel control switches cutoff, then run". There is no significant pause in that action because it's only to reset the electronic engine controls, so the 10 second gap between setting them back to "run" is not explained by the dual engine failure procedure but perhaps by a startle factor. One way or another, your eyes are going to end up checking where those switches are.
hec7or
July 15, 2025, 10:39:00 GMT
permalink
Post: 11922817
Originally Posted by mr ripley
The only time that both fuel control switches are switched off together (and not immediately switched back on - Double Engine Failure) is at the end of the flight once parked on stand.
It is also part of the evacuation drill, as practiced regularly during recurrent training in the simulator. If a high stress situation had developed after V1, a "brain fart" may have resulted in the deliberate but unintended switch selection.
JustusW
July 15, 2025, 10:55:00 GMT
permalink
Post: 11922831
Originally Posted by hec7or
It is also part of the evacuation drill, practiced regularly during recurrent training in the simulator. If a high stress situation had developed after V1, a "brain fart" may have resulted in the deliberate but unintended switch selection.
One of the initially discussed variants was inadvertent operation of the Fuel Cutoff Switches instead of putting up the landing gear. There was some pushback against that idea based on the position of the landing gear. As far as I recall the observed position of the landing gear was ultimately deemed to be caused by loss of hydraulics, and not as caused by interruption of the raising operation, making it fully compatible with the preliminary report. It's curious that the report does not mention the positive rate and gear up call out, either for its absence or it being made. It does note that the landing gear lever was in the down position, which isn't unusual for a severe event just after V2 but also in line with the theory.

With what we know now from the preliminary report that option seems to be a good candidate as the source of initiation for an action slip. Both the PF instead of calling Gear Up Action Slipping and operating the Cutoff Switches, or the PM instead of calling Positive Rate doing so would fit that scenario and timeline.
Dimitris
July 16, 2025, 14:26:00 GMT
permalink
Post: 11923766
Originally Posted by tdracer
Not trying to be part of the on-going hamster wheel. But the discussions regarding the odds of this being pilot suicide based on historical rates are missing a very critical statistical point.
Let's just assume that rate of commercial airliner crashes due to pilot suicide is 1 in 100 million departures. Simply put, that means that if you get on a commercial aircraft to fly from point A to point B, the historical odds are that there is a 1 in 100 million chance that your flight will crash due to an intentional suicidal pilot act. However, the historical odds say that the odds of your flight crashing for any reason are several million to one. Since the turn of the century, the fatal cash rate has been something around 1 in 5 million departures.
Now, we know for a fact that the Air India 787 crashed - hence the probability of a crash for this particular flight is not 1 in 5 million - it's ONE! That means the historical odds of this crash being due to an intentional act by a pilot (i.e. suicide) is ~5%, not one in 100 million (obviously a rough number, but you get the idea).

Oh, another to consider with regard to a pilot having a monumental 'brain fart'. We don't know where the pilot's mind was at during the takeoff. Was he focused on the task at hand, or was he preoccupied with the health of his father and what he was going to do about it. About 35 years ago, my one-time fianc\xe9 left me for another guy. I was devastated. Some of my friends were worried that I might attempt suicide, but that never entered my mind. However, I was horribly distracted and my work performance suffered greatly since my mind was not on the tasks at hand. I could have easily done something really stupid that could have endangered my life - such as missing a stop sign while driving or running a red light because I wasn't paying attention.
Originally Posted by Xeptu
I have to say I'm really impressed with your work. It's no co-incidence that this image has been used noting that the rat is deployed which means the generators are already offline,
I'm equally impressed by how quickly No1 engine recovered. I think it's safe to say that this situation is not recoverable, but a truly impressive piece of engineering all the same.
SLF here with engineering background.

Regardless of what happened and why regarding the switches going to off, there is now a documented failure mode of the system that needs mitigation (?):
Fuel switches off at less than XXX ft lead to unrecoverable AC.

If fuel cut off during take off leads to unrecoverable at less than XXX ft or risk of error i.e. switching one vs the other, then inhibit them. I'm putting it too simplistically, but if after V1 the AC is GO and there is a range of altitude/speed that engines loss leads to unrecoverable some mitigation is needed.

In the meantime maybe ban jump seating during such phases of flight regardless of it is relevant to this accident. If there is intention for something like that, less people with access reduces the possibility of happening.

Too much discussion I think for the 10s to bring the switches back to on.... Pilots are not super humans. By that time the situation the AC was at must have been very clear, some hands shaking is expected...

I wonder if based on the data from the flight, sim-runs have been made to see if the situation would be more survivable had the AC 'slammed' itself back to the runway.

--> Any estimation of how many seconds in 'off' would not change the end result? If it is 2-3 seconds, its better to stop discussing if 10s response by pilots was ok or not. The 'why' and 'preventive' of going to 'off' is a lot more important.

Edit: Have been reading tdracer posts for many many years now. Thank you!

Last edited by Dimitris; 16th July 2025 at 14:31 . Reason: avoid post being regarded as 'dry' or confrontational to exceptional professionals on this forum
GarageYears
July 16, 2025, 14:36:00 GMT
permalink
Post: 11923772
Originally Posted by Dimitris
SLF here with engineering background.

Regardless of what happened and why regarding the switches going to off, there is now a documented failure mode of the system that needs mitigation (?):
Fuel switches off at less than XXX ft lead to unrecoverable AC.

If fuel cut off during take off leads to unrecoverable at less than XXX ft or risk of error i.e. switching one vs the other, then inhibit them. I'm putting it too simplistically, but if after V1 the AC is GO and there is a range of altitude/speed that engines loss leads to unrecoverable some mitigation is needed.

In the meantime maybe ban jump seating during such phases of flight regardless of it is relevant to this accident. If there is intention for something like that, less people with access reduces the possibility of happening.

Too much discussion I think for the 10s to bring the switches back to on.... Pilots are not super humans. By that time the situation the AC was at must have been very clear, some hands shaking is expected...

I wonder if based on the data from the flight, sim-runs have been made to see if the situation would be more survivable had the AC 'slammed' itself back to the runway.

--> Any estimation of how many seconds in 'off' would not change the end result? If it is 2-3 seconds, its better to stop discussing if 10s response by pilots was ok or not. The 'why' and 'preventive' of going to 'off' is a lot more important.

Edit: Have been reading tdracer posts for many many years now. Thank you!
The problem here with inhibiting the fuel cutoff is that what happens if you have an engine fire less than your XXX ft? You still need to turn off that engine, right? Now you could say turning off BOTH should be inhibited... what if they are both on fire and there's a nice flat space in front of you?

- GY
Dimitris
July 16, 2025, 15:57:00 GMT
permalink
Post: 11923826
I repeat: SLF here

Originally Posted by GarageYears
The problem here with inhibiting the fuel cutoff is that what happens if you have an engine fire less than your XXX ft ? You still need to turn off that engine, right? Now you could say turning off BOTH should be inhibited... what if they are both on fire and there's a nice flat space in front of you?

- GY
Not 'my' XXX ft (my bold in quote)
I read elsewhere in this thread that 'below 400ft (or whereabouts) no actions from the crew' as an SOP. What I read as SLF engineer --> between V1 and 400ft certification flies the AC unless there is failure outside certification bounds in which case we need the professional to attempt to save the day. So... what was the emergency IF hands were at switches area during that phase of the flight?

Originally Posted by EXDAC
I have seen no documentation of such a failure mode. There are many flight crew actions that can cause loss of the aircraft but these are not failure modes. In any event the need for mitigation of a catastrophic failure mode depends on the probability of its occurrence.
Read the part that both switches were set to 'off' in the report. Even if they were not and this is aliens, it is documented now.
I wrote that I'm SLF. For me the pilots or whoever is upfront is also a potential failure mode on the system.
I also wrote 'ban jump seating', you missed that.

Originally Posted by EXDAC
Pull the fire handle(s)? Or do those that want the fuel switches to be inhibited also want the fire handles to be inhibited?
How do you tell there is an engine fire from the cockpit? Same thing that tells you on the AC side can un-inhibit them. Or add a switch
If there is engine fire alarm at Vr what do SOP say?

FBW control law of AC has several modes that doesn't let pilots do stuff. How do you switch from the one to the other as a pilot? Same can go with engines control.

To avoid misunderstandings: I'm the type that wants human pilots at the front.
nrunning24
July 16, 2025, 18:15:00 GMT
permalink
Post: 11923900
Originally Posted by Dimitris
SLF here with engineering background.

Regardless of what happened and why regarding the switches going to off, there is now a documented failure mode of the system that needs mitigation (?):
Fuel switches off at less than XXX ft lead to unrecoverable AC.

If fuel cut off during take off leads to unrecoverable at less than XXX ft or risk of error i.e. switching one vs the other, then inhibit them. I'm putting it too simplistically, but if after V1 the AC is GO and there is a range of altitude/speed that engines loss leads to unrecoverable some mitigation is needed.
Boeing's whole differentiation from Airbus in design is they want the pilots to have more control. Also this would never pass certification muster. Adding more automation doesnt always make things safer, lots of unintended consequences. At some point you just have to accept when you fly your life is in the pilots hands for good or bad.