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KSINGH
July 12, 2025, 18:33:00 GMT permalink Post: 11920737 |
One suggestion about why the report was sanitised and a fuller transcript was not provided could be to delay public reaction on this and avoid copycat events.
Jump seaters should be mandatory on all flights. On AS2059 the jumpseater maniac was overpowered by the other pilots. Two against one is better than pilot against pilot. The 10 second delay could be explained by a cabin altercation when one pilot saw the other one deliberately perform the cutoff. and frankly having spoken to some of these cabin crew who are quite open about their mental \x91struggles\x92 I can\x92t say I\x92d feel more secure with them sat out of my eye line but within reach of certain critical controls\x85. wasn\x92t the 2 person rule initiated after Germanwings and then quite quickly abandoned because many airlines saw the risks of cabin crew in the flight deck more routinely with a single pilot as more of a risk factor than the alternative? |
KSINGH
July 12, 2025, 18:37:00 GMT permalink Post: 11920741 |
as per the report- at *most* 1s apart, particularly significant given that it has been mentioned the recording interval of the DFDR is 1s
also I don\x92t know if we\x92ve had an adequate answer to the fact of what data streams the DFDR records, was it only detecting the electrical signal of fuel cut off or the actual position of the toggles- I don\x92t believe it would be the latter which opens an entirely different rabbit hole |
X-37
July 12, 2025, 18:46:00 GMT permalink Post: 11920744 |
A question from an accepted standpoint of relative ignorance - neither a pilot nor hugely familiar with 787s although have spent a lot of time around both.
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, is there any condition that could have led a pilot to reach for the stab cutoff at the critical moment? Recurrence of the tech defect from the previous sector or switches being left in the wrong position but not noticed under the red guards ? If that\x92s possible then accidental action of the fuel cutoff switches when the intent was some intervention with the stab switches seems more likely than a wilful pilot action to cut off fuel flow. Is that remotely possible, given the defect history? |
42go
July 12, 2025, 18:52:00 GMT permalink Post: 11920747 |
Rather confusingly, AvHerald carries this today
"On Jul 12th 2025 (UTC) India's media report that the investigation is NOT focussing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure." I have no idea what provenance to attach to that! |
BraceBrace
July 12, 2025, 18:54:00 GMT permalink Post: 11920749 |
Question:
What messages, if any, are displayed on-screen when the fuel cutoff switches are re-positioned (especially to OFF)? I'm wondering if the pilot who asked about the shutoff SAW the other pilot manipulate the switches or if he was alerted by a message... or perhaps he looked down at rollback and realized they were in the OFF position. I believe (long time ago experience) there is an EICAS alert popping up when the fuel control switches are moved to cutoff. However, Boeing has a philosophy of "inhibits" below 400ft the aural alert indicating an EICAS has popped up is one of them. So as PF you would have to look at the EICAS during rotation, read the alert, then look down at the switches instantly. |
andrasz
July 12, 2025, 18:55:00 GMT permalink Post: 11920750 |
Signal routing from cutoff switch ?
I see pages of deliberation on the physical position of the switches, but I have not seen a single post on how the signal from these switches is actually routed and processed. I have no knowledge of 787 systems, but I rather suspect that the signal is fed into the FADEC or some intermediate processor rather than directly opening/closing the fuel pumps relay switch ... ? Similarly the switch position signal is I presume captured and processed by a separate system which then writes it to the FDR. Anyone in the know whether there is any possible failure mode of the electronics that would simultaneously send the cutoff signal to FADEC and result in an OFF position for the switch at the same time without any actual physical movement of the switch ?
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Feathers McGraw
July 12, 2025, 18:59:00 GMT permalink Post: 11920753 |
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'm also reminded of the Moorgate tube train crash in 1975, no one has ever determined why an experienced driver who had driven the short out and return route 4 times that day suddenly accelerated while bringing his train into a terminus station with a closed tunnel beyond the platform end. As someone married to a person who suffers with epilepsy, I'm used to short term memory interruption events where my wife will have done something and then not remember doing it 10 seconds later. I suppose such a thing in a pilot is a possibility, a new sufferer may not even realise that they have this kind of condition or even know they have performed an action. I don't have anything else I can add to this, I read the preliminary report twice and checked every word. It doesn't offer any clear suggestions without expanding on the limited information provided. Undoubtedly the investigators have a lot more information they can examine but it will take time. One thing is that it doesn't mention a positive rate call, in the circumstances that suggests that this wasn't made and was replaced with the "Why did you cut-off?" question. I note that this crash might have been more survivable with a 15 degree change of heading to the left towards a more open area to the south of the 5 buildings involved, but of course there would be no reason for the crew to have done this or indeed any time to do it. |
sevenfive
July 12, 2025, 19:21:00 GMT permalink Post: 11920769 |
I don\x92t know if the FDR measures the switch position or the electrical signal. The latter is probably more likely, although there has been much discussion around potential scenarios involving accidental switch movement as well as possible causes of electrical glitches. Let\x92s assume that the switches were actually moved, and ignoring the \x93bad faith\x94 scenario, we need a situation that encompasses the switches being moved to Cutoff by one pilot, this action being queried by the other pilot and denied by the pilot who moved the switches.
For consideration, here is a possible scenario that hasn\x92t been mentioned yet and encompasses the frailty of human performance. The report mentions that the flight crew on the immediately prior flight had written up a "STAB POS XDCR" status message, and that troubleshooting was carried out. I wonder if the scenario could be that the accident crew received a Stabiliser EICAS message on or around take-off and the Capt (who was PM) decided to action the first checklist item immediately from memory, by intending to move the Stab switches to Cutoff but moving the fuel switches instead. As in all modern Boeings, the Stabiliser Cutoff switches are immediately next to the Fuel Cutoff switches and operate in the same sense (i.e. down for Cutoff). They are guarded and never normally moved but, with an intent to move the stab switches, \x93muscle memory\x94 (cerebellum activation if you prefer) may have taken the Captain\x92s hand to the Fuel switches, which are operated on every flight. The FO (who is PF) is manually flying at this stage sees and queries it. The Capt denies it, as he doesn\x92t realise what he has done (confirmation bias perhaps). After a few seconds, the terrible mistake is realised, and the fuel switches are moved back to run, but sadly too late and the Capt makes a Mayday call. Perhaps a bit of a stretch but not as much of a stretch as many of the other scenarios in this thread. I think it is a real possibility. Sadly, the only other explanation that I can see is the deliberate \x93bad faith\x94 scenario, which we would all hope is incorrect. Fly Safe PJ88 |
tdracer
July 12, 2025, 19:29:00 GMT permalink Post: 11920772 |
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. The left and right engine wiring is physically isolated from the other engine - nothing gets routed in common bundles between the engines. Hence there is simply no way a localized issue could affect both engine's wire bundles. So we're talking two independent events that cause the switch output to electrical change state between RUN and CUTOFF without associated switch movement. So now were out in a 10-16/hr. territory. Now, these independent events both occur a second apart - 3,600 seconds/hr., so we've just added ~8 orders of magnitude to the dual failure probability number (10-24/hr.). Now, they both somehow return to normal withing a few seconds of each other - another ~8 orders of magnitude so we're talking 10-32. That means the probability of this happening at any time since the Big Bang is way less than one.... Space aliens look reasonable in comparison. So can we discuss things that might actually have happened? |
Mrshed
July 12, 2025, 19:37:00 GMT permalink Post: 11920779 |
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. The left and right engine wiring is physically isolated from the other engine - nothing gets routed in common bundles between the engines. Hence there is simply no way a localized issue could affect both engine's wire bundles. So we're talking two independent events that cause the switch output to electrical change state between RUN and CUTOFF without associated switch movement. So now were out in a 10-16/hr. territory. Now, these independent events both occur a second apart - 3,600 seconds/hr., so we've just added ~8 orders of magnitude to the dual failure probability number (10-24/hr.). Now, they both somehow return to normal withing a few seconds of each other - another ~8 orders of magnitude so we're talking 10-32. That means the probability of this happening at any time since the Big Bang is way less than one.... Space aliens look reasonable in comparison. So can we discuss things that might actually have happened? |
jimtx
July 12, 2025, 19:53:00 GMT permalink Post: 11920787 |
I flew the 777. The 78 switches are of similar design. They must be positively lifted and then moved with a robust over center block preventing them from moving after being bumped by something or other. Nothing I can think of in the cockpit could hit them with enough force to break the over center lock. IIRC none of our fleet had the side guard. It takes a conscious act to move them. The stabilizer trim cutouts are completely different red guarded switches.
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GroundedSpanner
July 12, 2025, 20:09:00 GMT permalink Post: 11920799 |
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? |
island_airphoto
July 12, 2025, 20:09:00 GMT permalink Post: 11920800 |
I know.......it could turn out to be some way out cause no one has thought off. A buddy went down with double engine failure in an Aztec, when he switched tanks water that had leaked into the airplane formed an ice ball that jammed the cables to the actual switches between tanks and cut off all fuel. If he hadn't landed in a field and gotten an A&P on it before the temps went above freezing maybe no one would have ever known why 2 engines with totally separate fuel systems died at the same time. Last edited by T28B; 12th July 2025 at 20:12 . Reason: split out the novel failure story in its own paragraph |
pampel
July 12, 2025, 20:12:00 GMT permalink Post: 11920803 |
In the case of (2) or (3), would the expected response be "Why did you cutoff"?
I would have thought a pilot would notice the engines spooling down, and comment on that. To immediately jump to the cutoff switches as the cause rather implies something drew attention to the switches. Then there is a 10+ second gap before the switches are set to run again. I can't think of any good reason why the PNF would have taken so long to correct an accidental or deliberate manipulation of the switches. The truth will be in what was said after 'I didnt', but that's conspicuously absent from the report. |
za9ra22
July 12, 2025, 20:16:00 GMT permalink Post: 11920805 |
It pretty much can and the odds are vastly in favor of a human hand on the switches. I *hate* the idea someone is either that clueless turning off random things or that evil, but the odds of anything else being the cause are rapidly approaching being hit by lightning after winning the lottery.
I know.......it could turn out to be some way out cause no one has thought off. A buddy went down with double engine failure in an Aztec, when he switched tanks water that had leaked into the airplane formed an ice ball that jammed the cables to the actual switches between tanks and cut off all fuel. If he hadn't landed in a field and gotten an A&P on it before the temps went above freezing maybe no one would have ever known why 2 engines with totally separate fuel systems died at the same time. |
njc
July 12, 2025, 20:18:00 GMT permalink Post: 11920807 |
as per the report- at *most* 1s apart, particularly significant given that it has been mentioned the recording interval of the DFDR is 1s
also I don\x92t know if we\x92ve had an adequate answer to the fact of what data streams the DFDR records, was it only detecting the electrical signal of fuel cut off or the actual position of the toggles- I don\x92t believe it would be the latter which opens an entirely different rabbit hole Regarding your second point: it has been noted by multiple posters that "the actual position" of the switch is a fairly meaningless concept for the EAFR data if you want to exclude the electrical signal arising from the switch itself. So I have to ask: what would you regard as a measurement of the "actual position of the switch", in this context? |
tdracer
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? 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 ( ![]() |
Sailvi767
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. |
Engineless
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 ,
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.
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 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. |
T28B
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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