Posts by user "BrogulT" [Posts: 46 Total up-votes: 0 Pages: 3]

BrogulT
June 20, 2025, 14:02:00 GMT
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Post: 11906995
Originally Posted by Feathers McGraw
VT-ANB flew DEL-AMD, approximately 1hr 15 minutes, before its fatal departure from AMD.

Does anyone know if fuel was added at AMD or was the total fuel required to LGW already aboard on departure from DEL?
I think that even if the DEL-AMD leg were flown totally empty for repositioning that it still would have been over MLW if it carried enough fuel for AMD-LGW. And we know from witnesses that the DEL-AMD leg was not empty. AMD is a regular stop for AI and has fuel, why would they tanker it in?

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BrogulT
June 21, 2025, 19:48:00 GMT
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Post: 11908009
Originally Posted by GroundedSpanner
30+ years of my experience as an aircraft engineer that forms a plausible (IMO) explanation of what may have happened.

That wing tank fuel could have picked up a fair amount of water.

It is conceivable to me that the suction tube pickup could have been immersed in water, settled out from the fuel in the wing tanks.
A supply likely heavily water contaminated. It would take a few seconds for that contaminated fuel to actually reach the engines, but when that contaminated fuel hit, Thrust would have been significantly reduced. The EEC's would have been doing their best to maintain the thrust, firewalling the throttles would probably have little effect at that exact moment. The engines would have likely worked through that bad fuel in a shortish period of time, but a period of time that our crew did not have.
I don't want to refute your theory, but given your 30 years of experience---presuming it is relevant--I'd ask you to clarify a few things.

First, water in fuel is not a novel concept and I would presume that the designers of the 787 knew about it. You've simply stated that water might collect and settle out, but how much water might you expect under those conditions (57% humidity doesn't seem terribly high to me) and what features and procedures are already there to mitigage water contamination issues? Your theory would imply that there basically aren't any. IDK how the tank venting system works, but the idea that some huge amount of water could have condensed in the tank from the outside seems preposterous.

Second, how much water do you think it would take to cause a sustained flameout in one of those engines? Remember that they have automatic continous relight, so you're going to have to sustain your flame suppression long enough for them to wind down completely. I think those engines were probably using something like 2 gallons per second of fuel along with 250lbs of air heated to over 1100F. Any fuel in the mix would burn and the water would be converted to steam so you'd need mostly water for a long time. So if you think a hundred gallons of water could have gotten into each tank then perhaps I'd buy your theory--which, btw, does fit the known facts pretty well. But I think that short of some woeful neglect, Boeing and AI already know about and have methods of dealing with water contamination. At least I hope so.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Relight

BrogulT
June 21, 2025, 20:48:00 GMT
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Post: 11908045
Originally Posted by ManaAdaSystem
It\x92s quite possible that they carried economy fuel on this sector.
What is "economy fuel"?

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BrogulT
June 22, 2025, 00:03:00 GMT
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Post: 11908164
Originally Posted by Lead Balloon
Perhaps my earlier post was incredible and that's what prompted the SLF's question.
Whichever the design and outcome, there will be benefits and there will be risks.
What boggles my mind (if my understanding is correct) is that you have redundant systems that use that redundancy not to make sure that they never accidentally shut down an engine improperly but rather to make sure they never fail to shut down an engine if even one channel thinks it should. AFAIK engines not returning to idle have not killed anyone yet (the engine can typically be just turned off or the fire handle pulled once the crew decides they want the engine to die) but engines shutting off at a bad time are an obvious hazard.

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BrogulT
July 10, 2025, 15:01:00 GMT
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Post: 11919078
Originally Posted by Magplug
Propellerhead You are correct, a low level altitude capture would back off the throttles as the FMA goes into ALT.
Would the throttles really roll back right away even at that low airspeed?

Subjects: None

BrogulT
July 11, 2025, 21:48:00 GMT
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Post: 11919853
Originally Posted by KSINGH
I doubt you\x92d have got such immediate positive intervention from most line crews faced with the same circumstances and time
I think most line pilots, upon noticing that the fuel levers were in cutoff right after rotation, would immediately turn them back on. I don't think it would take 10 seconds--or even 5--to get that handled as I imagine most professional pilots would quickly grasp the seriousness of the problem. The only explanation I can think of for even that short delay--one that may have made a big difference--is the authority gradient between Captain and FO. But the preliminary report doesn't give us the level of detail we'd all like to have so it probably isn't possible to 100% support any specific conclusion just yet.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Authority Gradient  Fuel (All)  Fuel Cutoff Switches  Preliminary Report

BrogulT
July 12, 2025, 00:16:00 GMT
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Post: 11920034
Originally Posted by medod
I imagine that what happened with engine 2 ("able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery") will be a major part of the investigation.
It won't be an issue, the cause is simply that they were below the airspeed needed for a successful airstart, the engine had spooled down too far to recover without being cranked and there was no power available from the APU yet. As far as knowing how long they were from #1 providing meaningful thrust, you'd need to have a lot more data to know. Another 30 seconds probably would have helped a lot.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU  Relight

BrogulT
July 13, 2025, 14:05:00 GMT
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Post: 11921344
Originally Posted by galaxy flyer
FDX jump seater was a disgruntled employee, not any kind of crew.
He was a former Navy pilot employed as a FedEx flight engineer. Obviously he wasn't part of the assigned crew on that flight, but he was a qualified crewmember not just some random FedEx forklift driver.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Jump Seat

BrogulT
July 13, 2025, 14:32:00 GMT
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Post: 11921359
Originally Posted by paulross

I'm not saying people intent on this behaviour are being rational but even by the laws of un-rationality it seems an unlikely way of trying to achieve your goal.
Analyzing the rationality of someone in this situation isn't easy but there are some common threads from past incidents like FDX 705 that may help. If you start with the idea that the person in question doesn't want to continue their life but wants to conceal their suicide to make it look accidental for reasons of legacy, life insurance or whatever, then you'll see that their options become much more limited. Also, unlike a terrorist, they may not specifically want to kill a planeload of people but they are somehow willing to accept that as collateral damage. Unless they are outright delusional as in the AA/Horizon inciident, I think that last part takes a particularly specific type of mindset that should be the subject of psychological study. I'm not an expert of any kind in this area, but I don't think simple depression or suicidal ideation would suffice.

If it was an action by the captain, then claims that the plan was unlikely to succeed are disproven by the fact that it did succeed and probably with at least a few seconds to spare. He would have known that it would take a short bit of time for the FO to fully figure out that both engines had stopped and why. He would have known that shutting down for more than 10 seconds would spool down the engines far enough to make a relight either slow or unlikely and if need be, he could take further action. He also would have known that a crash into urban Ahmedabad would be catastrophic. I'm not saying his plan was perfect, but it is "reasonable" considering the stated goals and options available.

Last edited by Senior Pilot; 13th July 2025 at 17:54 . Reason: Unacceptable accusation at this time

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Relight

BrogulT
July 13, 2025, 16:09:00 GMT
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Post: 11921411
Originally Posted by OldnGrounded
And I don't think we have any compelling evidence that the intent was to crash the aircraft and kill everyone aboard.
I would suggest everyone that wants to analyze the likelihood of particular actions on the part of the crew, whether referring to "muscle memory" or "brain farts" or whatever, simply add the phrase " during the initial climb " to their thoughts and see how that sounds. Without callouts for raising the gear and other than sleepwalking, what explanation is there for flipping the fuel cutoffs down in sequence? And further, doing so precisely in the time window where it was most likely to make the situation unrecoverable?

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Muscle Memory

BrogulT
July 13, 2025, 16:27:00 GMT
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Post: 11921424
Originally Posted by Mr Optimistic
I suppose this event will be a setback for any ambition for single pilot operation.
Well, it will be a single pilot plus the new HAL9000 system.

Subjects: None

BrogulT
July 13, 2025, 20:29:00 GMT
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Post: 11921621
Originally Posted by Mrshed
The question is what impact was had on attempts to recover the aircraft by the (presumed) lack of most or all electrical power.
From the point that the fuel cutoffs were switched back to run, the primary (perhaps only) relevant issues were time and altitude. The left engine was relit and recovering on it's own but the right would probably have needed cranking as it appears to have had a hung start because it was spooled down too far and the airspeed was too low. However, I'm pretty sure that even if the APU had already been running at takeoff, they still would have needed at least another 30 seconds if not longer for full thrust. Also, there was nowhere near enough time for the APU to start and come online here.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU

BrogulT
July 13, 2025, 21:18:00 GMT
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Post: 11921673
Originally Posted by galaxy flyer
It\x92s entirely possible, there was \x93positive rate\x94, \x93gear up\x94 exchange followed by the movement of the switches by the PM, followed by \x93why did you cut off\x94 by the PF who is soon without a PFD.
If that were the case I'd certainly concede that we might have a much different story here. But also, if that were the case I think it would reflect extremely poorly on the Indian AAIB (who I currently hold in high regard) and their preliminary report. That would be a truly monumental omission that would cause me to seriously question their motives. I also think it would leak pretty quickly. I know the Indian ALPA wanted observer status in this investigation but I'm not sure if they got it or not.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All)  AAIB (India)  Preliminary Report

BrogulT
July 13, 2025, 21:54:00 GMT
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Post: 11921706
Originally Posted by andihce
Meaning no disrespect to pilots (indeed, quite the opposite), and admittedly I'm no psychologist, but it strikes me that to postulate that a pilot might cause the crash of a large aircraft because of suicidal thoughts is to seriously understate the action taken , because such action also means the likely death of all passengers and aircrew, presumably all or most of whom are perceived as innocent bystanders by the actor. Whatever term you want to apply to that action, it is far more and far worse than individual suicide, and I would think it needs a pretty substantial and convincing body of evidence, including psychological evidence, to explain..
I agree that deliberately crashing a passenger airliner is something more than ordinary suicide. IMO it goes way beyond a despondent person that just doesn't consider the effect on their family or those that might be affected or injured when they crash their car or jump out of building. A pilot who does this is murdering a bunch of innocent people who trusted them to keep them safe. We don't have to explain it to know that it happens and whatever psychological state that causes it is real. And I think there is probably a big difference between someone that commits such an act without trying to create a plausible cover-up (Germanwings) vs someone who tries to make it look like an accident (FDX 705) or someone who may just be making some sort of point (MH370).

Unless we face up to, study and discuss these issues they'll keep happening occasionally, perhaps even more frequently. If we keep going with preventing pilots from getting assistance by giving them a choice to 1) pretend everything is OK or 2) immediately hand in their medical, we'll stay right where we are.

Subjects: None

BrogulT
July 13, 2025, 22:14:00 GMT
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Post: 11921727
Originally Posted by paulross
I assume something of the same happens in India. However, I can not find any evidence online that a criminal investigation has been launched there and it seems AAIB (India) continues to lead the investigation.
This suggests that, with all the evidence gathered by the investigators so far (which is substantial), there are no grounds to conclude that a criminal act had been committed.

In other words, this is an accident and not deliberate.
The difference is that Indian police agencies are often extremely reluctant to take cases unless they have to. There are varous reasons that I won't try to explain but I wouldn't take the fact that the IPS or other agencies haven't publicly taken over the investigation yet as having any meaning. I would hope for more transparency but I would not be shocked if this ends up with the Indian equivalent of what happened with China Eastern 5735. Or perhaps pressure will be applied in a positive direction and they'll take and crack the case.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All)  AAIB (India)

BrogulT
July 14, 2025, 04:36:00 GMT
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Post: 11921851
Originally Posted by skyrangerpro
The extract below shows that from Idle to 83% N1 took 5 seconds after the initiation of a TOGA, so I think your estimate of 30 seconds is probably too high. However, after reading that report, I am of the opinion that AI 171 had no chance of recovering. If the FCS switches had been set to Run within 5 seconds of being set to Cut Off, there might just have been a chance, but it is not at all certain.
As I understood the question, the issue was what impact the lack of electrical power had on the restart. In this case, without the APU (or the other engine) for power the right engine was apparently never going to start despite heroic efforts on the part of the FADEC. With the APU running it could have been cranked. However, going from flight idle to full thrust is one thing, going from so far below idle that the engine needs to be cranked to flight idle will take a lot more time. How much more IDK since exactly how far the N2 speed had dropped, actual airspeed, temperature, etc are all factors. My guess is that it would feel like the engine was taking a million years to start. But the APU was not running and the point is moot.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU  FADEC  Fuel (All)  Fuel Cutoff Switches  Relight  TOGA

BrogulT
July 15, 2025, 13:03:00 GMT
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Post: 11922916
Originally Posted by JustusW
There is a 10 second gap between cutting fuel and re-enabling it and a 4 second gap between switches during re-enabling. Is there a mechanical reason why these switches would be slower to operate in either direction? There are obviously reasons such as startle factor and stress that might negatively affect the speedy operation of switches by anyone, but I am nonetheless curious if this might not be a pointer to some sort of mechanical issue after all, such as asymmetric wear or FOD.
Originally Posted by etrang
The fuel switches were switched off with a gap of 1 second (allowing for 1Hz sampling, between 0 and 2 seconds).
They were switched back on, about 10 seconds later, with a gap of 4 seconds (between 3 and 5 seconds).
What might account for the much slower switch on, especially given the serious nature of the situation?
One possilble reason (of many) is that the switches were turned off by someone who was otherwise unoccupied but they were turned on by someone who was busy trying to fly an airplane. Unless there was some deliberate effort to gum them up or damage them, I can't imagine mechanical faults suddenly appearing in the switch locking mechanisms right at that moment.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All)  Fuel Cutoff Switches

BrogulT
July 15, 2025, 14:03:00 GMT
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Post: 11922970
Originally Posted by barrymung
There quite possibly are multiple contacts in use
"Quite possibly"? A qualified, informed person has taken the time the share exactly how the 4 sets of contacts work on this switch and how they are connected to the plane's electrical system. Go back and find that and read it. It's not an open question. Broken or shorted wires would show up as specific faults, not as just a misreported switch position.

As for the locking mechanism, I don't have this switch but I do have various electronic devices with multiple examples of locking toggle switches with similar functions. They all share a common attribute in that while you can sort of balance the toggle in the middle, the internal toggle mechanism will not snap and change state until you go past that point. So if the switch is in the OFF position, it will not turn on until you go over the hump--and vice versa. So to get the switch in that condition you'd have to first switch it on and then back it off to the middle position. IDK for sure how the specific switches in question behave, but snap-action toggle mechanisms are pretty universal so I'd assume they are similar unless someone with access to one says otherwise.

Last edited by BrogulT; 15th July 2025 at 14:59 .

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BrogulT
July 16, 2025, 18:08:00 GMT
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Post: 11923894
Originally Posted by JustusW
That being said, I fail to see the similarities of either case and the Air India accident. All known pilot suicides and all suspected ones happened in cruise, not during takeoff.
That's a not a very meaningful common characteristic to use for comparing these events. Anyone who studies human behavior should include the ability to adapt to their analyses. Bacteria adapt to antibiotics by evolving, armies adapt to new weapons by adopting new defensive techniques and suicidal people who want to jump off a bridge can adapt to a chain-link fence by bringing a wire cutters. The obvious hole in your anti-theory here is that part of the theory of most known or suspected pilot suicides involve getting the other crewmembers out of the cockpit. Now that many airlines have adopted policies to prevent anyone from being alone in the cockpit, anyone contemplating suicide by crash will have to come up with a new plan. Now add in the addtional requirement that they hope to "die heroically" as a someone has previously said and now you have an even narrower set of possibilities.

Last edited by BrogulT; 16th July 2025 at 22:05 . Reason: clarity

Subjects: None

BrogulT
July 16, 2025, 22:20:00 GMT
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Post: 11924037
Originally Posted by fgrieu
What type of switches are they: SPST, SPDT with 3 wires used ? For SPST or equivalent, is "cutoff" the "make" or "break" state ?
Is there a common connection for the two switches, like a ground return or common live?
From earlier and from the Honeywell datasheet these are 4PDT switches with all 4 section having the center as a common (ground AFAIK ) so that the FDR and other circuits can positively see that the switch is on one condition or the other--except for the brief time that both are open during switching. Snap toggles like this are most commonly break-before-make as tdracer confirms (but 50ms seems like a long time...). What this means practically is that a break or short in the wiring would cause a fault that would be recognized as such since a correctly operating circuit will have one or the other but not both of the circuits completed and there are 4 sets of circuits.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FDR  Fuel (All)  Fuel Cutoff Switches  Honeywell