2025-06-15T19:20:00
permalink Post: 11902742
Have never flown 787. Comment only about the investigation which is underway.
With GE and Boeing sending expert reps to India (engine and aircraft manufacturers respectively) digging into the details should inform them of what occurred, but as I understand the process, the public information flow will come from the Nation whom they are assisting.
Have any of you who have done investigations at this level seen it work out otherwise?
Aside: five of my work colleagues were either born in Gujarat, or their parents were. I asked
"I realize that India is a very big place, but are you concerned about any relatives being among the casualties?"
I got four head shakes (no) and one reply that got me to almost spill my coffee.
"Nobody in my {extended} family would live near to an airport. It's too noisy."
It took me a second to register that as a "no" presented in a way that I wasn't expecting.
Subjects: None
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2025-06-17T20:35:00
permalink Post: 11904634
Last edited by Lonewolf_50; 17th Jun 2025 at 21:17 .
Subjects: TCMA (All)
2025-06-21T23:36:00
permalink Post: 11908151
That is what you are missing.
Also, so far there is no evidence I've seen regarding the 'chicken-egg' problem, did the engines fall below idle (fuel, stall...) and this caused an electrical blackout (-> battery, RAT...) or did an EE problem cause the engines to reduce thrust (FADEC, SW bug...). And where is the common cause in all this? There has to be a systematic error common to both engines, an external failure affecting both or a dependent fault with one affecting the other within seconds. This is the only thing I think everyone agrees here. And I refuse to beleave the external failure or dependent fault was sitting in the cockpit.
I think it is something not common to every aircraft type for the last 50 years.
Based on the mishap investigations I did, more than one of which involved fatalities, there is a whole family of maintenance / company culture errors possible that seem to me to get short shrift in the discussion here: thread number 1 and thread number 2.
But here's the problem: Air India, for very understandable reasons, isn't about to open the kimono until they are forced to.
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2025-06-22T00:41:00
permalink Post: 11908191
Procedures - There's the (at my airline weekly I think) procedure to 'sump' the tanks. There are drain points in the tank. Valves that you can push in with a tool and fluid drains. As described earlier (and videos exist on YouTube), you drain about a gallon of fluid and examine it for water. Most often in temperate climates (my experience), there's a few 'beads' of water in the bottom of the jug, moving about like mercury.
Except when there's more.
Sometimes there's a clear line in the jug, half water, fuel above. And sometimes a gallon of water, that smells like fuel. You drain it until you are sure there's no water.
Except when there's more.
Sometimes there's a clear line in the jug, half water, fuel above. And sometimes a gallon of water, that smells like fuel. You drain it until you are sure there's no water.
Could 'that much' water have condensed in the tank? Well - There's the question. I guess the basis of the theory is that on descent into DEL, the wing tanks picked up some very humid air, which settled water into the tanks through the night. Then, as the theory I posited must work, the wing pumps must have circulated and suspended that water into the fuel.
By design, the water from the CDG-DEL arrival should have been consumed in the DEL-AMD Sector.
But desperately clinging to defending my theory (I appreciate this is a hole), lets assume that at DEL the pumps were running for a long time.
Lets assume that the pumps allowed the water to be dispersed within the tank prior to being used through the engines. Then - in the DEL-AMD sector, the wing tanks could have picked up more water.
How much water would cause a sustained flameout?
I never posited a sustained flameout. I posited a significant reduction in thrust. Listening back to the rooftop video, which at first we were all listening for evidence of RAT, there's also a rhythmic pop-pop-pop of engines struggling.
I think the engines were running, albeit badly.
Heavily water contaminated fuel will do that. It doesn't have to be 100% water. Just enough water to make the engine lose thrust. Your 2 gallons per second figure assumes the engine running at full flow.
I'm not a figures man, I'll not challenge that, I do recall flowmeters at max thrust spin like crazy. But an engine struggling due to a high percentage of contamination, is that using 2 gal/sec? or just trying to? What happens if there is e.g. 20% water in the fuel?
There are also reported incidents of engine flameout / thrust reduction that have all happened at altitude. Incidents that have been recovered due to the altitude and time available. I Posited that the engines would have eventually regained full thrust once the contamination worked though. But 30 seconds of rough engine is very different at 40,000 feet than it is at 100 feet.
The theory also relies on a second part - the electrical failure.
That the electrical failure causes the fuel supply to switch, a few seconds after the failure. We go, at the point of electrical failure from a pumped centre tank supply to a sucked wing tank supply. It takes time for that different fuel to reach the engine.
By design, the water from the CDG-DEL arrival should have been consumed in the DEL-AMD Sector.
But desperately clinging to defending my theory (I appreciate this is a hole), lets assume that at DEL the pumps were running for a long time.
Lets assume that the pumps allowed the water to be dispersed within the tank prior to being used through the engines. Then - in the DEL-AMD sector, the wing tanks could have picked up more water.
How much water would cause a sustained flameout?
I never posited a sustained flameout. I posited a significant reduction in thrust. Listening back to the rooftop video, which at first we were all listening for evidence of RAT, there's also a rhythmic pop-pop-pop of engines struggling.
I think the engines were running, albeit badly.
Heavily water contaminated fuel will do that. It doesn't have to be 100% water. Just enough water to make the engine lose thrust. Your 2 gallons per second figure assumes the engine running at full flow.
I'm not a figures man, I'll not challenge that, I do recall flowmeters at max thrust spin like crazy. But an engine struggling due to a high percentage of contamination, is that using 2 gal/sec? or just trying to? What happens if there is e.g. 20% water in the fuel?
There are also reported incidents of engine flameout / thrust reduction that have all happened at altitude. Incidents that have been recovered due to the altitude and time available. I Posited that the engines would have eventually regained full thrust once the contamination worked though. But 30 seconds of rough engine is very different at 40,000 feet than it is at 100 feet.
The theory also relies on a second part - the electrical failure.
That the electrical failure causes the fuel supply to switch, a few seconds after the failure. We go, at the point of electrical failure from a pumped centre tank supply to a sucked wing tank supply. It takes time for that different fuel to reach the engine.
Not sure if you are right, and not familiar enough with 787 to check the fuel flow logic, but a friend of mine dead-sticked a single engine trainer into a field due to water in the fuel ... 20 minutes after takeoff.
It could have happened earlier.
Subjects: Centre Tank Electrical Failure Fuel (All) Fuel Pumps RAT (All) RAT (Deployment)
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2025-06-28T22:49:00
permalink Post: 11912706
NYT illustrated the story, drawing the same conclusions as this thread so far:
https://www.nytimes.com/interactive/...ash-cause.html
https://www.nytimes.com/interactive/...ash-cause.html
Yeah, that's a concern that one can do nothing about, but I recall Egypt Air 990 having that same sort of obstacle to the investigation (cultural/political). (No, I am not saying that the causes are the same). My point is that each nation's transparency varies, regardless of what ICAO calls for.
From two threads I see this: a sudden loss of thrust was the initiating event after a successful take off - all of this other electronic stuff was a result of that.
What I will be paying close attention to is what information comes out as regards maintenance and ground handling for that particular hull...and what isn't said. (I guess that may be a while in coming - and I do agree in the general sense that giving the benefit of the doubt is a good position to take at this point in time).
Subjects: New York Times
5 users liked this post.
2025-06-29T12:57:00
permalink Post: 11913019
As per my training, don't let communicate interfere with aviate. If you can do both simultaneously, go ahead. For me, "communicate" could be taking your mind away from task to formulate and interact in discussion. So yes, we don't allow a complex discussion to preempt flying the plane. For me, pressing a mic switch and calling Mayday is more instinctive and muscle memory, than distracting. If a pilot got a Mayday out, good for them! I can't see it helping much for the doomed flight, other than being a valuable "very soon after the event" indicator that the pilots knew that something very bad was happening. I've known pilots to wrestle control for seconds/minutes in an effort to regain control, before issuing a Mayday. Okay, tasks in priority. But in this case, it appears that a pilot issued a Mayday even before control was actually lost - a valuable timestamp on the order of events for investigation.
In a pedantic sense: if you make control inputs, and the aircraft won't or can't respond to them, you are in out of control flight .
The whole event happened pretty quickly. How far into "we are doomed" that his senses told him they were can have informed his decision to say something about it. (the human mind is an interesting thing).
There's also the matter of temporal distortion which can happen during stress or high adrenalin events. (I experienced that during the course of an aircraft accident: not on topic for this thread).
As to conformance with ICAO, not all investigations make good on that.
Spoiler
I sincerely hope that this one does.
(Note: some of what I refer to as out of control flight seems to be called upset in commercial transport jargon).
Subjects: Mayday
2025-06-29T19:00:00
permalink Post: 11913178
A jet upset is an undesirable aircraft state...ie stall, or severe turbulence causing the aircraft to flip upside down dive etc... Looking at the Air India incident, the aircraft was not in any of those situations... In fact, if you weren't aware, you would think it was landing. This is something else entirely.
That said, your pedantry from a different angle is accepted.
Back from early flying, when you were first trying it out, your instructor taught you that Power plus attitude equals performance. (While true enough, power plus attitude plus configuration is a more accurate formulation).
That reply to you offered, yes, your response is well put.
(Maybe it's my rotary wing experience that puts "power" into what controls flight, but no matter, we are discussing a 787-8).
Glad to hear that the Indian Government has a timeline for a prelim report. If it takes them a bit more time than ICAO wants, with alerts or bulletins issued as various things are confirmed, that probably serves the larger interest.
Mohol also stated that "sabotage" has not yet been ruled out at this stage of the investigation.
Spoiler
Subjects: None
2025-06-30T13:08:00
permalink Post: 11913613
We know that the right-hand GEnx-1B was removed for overhaul and re-installed in March 2025 so it was at “zero time” and zero cycles, meaning a performance asymmetry that the FADEC would have to manage every time maximum thrust is selected. If the old engine was still on the pre-2021 EEC build while the fresh engine carried the post-Service Bulletin software/hardware, a dual “commanded rollback” is plausible.
A latent fault on one channel with the mid-life core can prompt the other engine to match thrust to maintain symmetry, leading to dual rollback.
A latent fault on one channel with the mid-life core can prompt the other engine to match thrust to maintain symmetry, leading to dual rollback.
Originally Posted by
silverelise
He also confirmed that all the data from the recorders has been downloaded and is being processed by the Indian AAIB,
no boxes have been sent abroad.
The 30 day deadline for the preliminary report is July 12th.
The 30 day deadline for the preliminary report is July 12th.
Originally Posted by
the linked article
Investigators still haven’t ruled out the possibility of sabotage being behind the Air India crash in
Ahmedabad
earlier this month that
killed 274 people
, according to India’s aviation minister. The Aircraft Accident Investigation Bureau (AAIB) has confirmed that the aircraft’s flight recorders – known as black boxes – will not be sent outside the country for assessment and will be analysed by the agency, said Murlidhar Mohol, the minister of state for civil aviation.l
Subjects: AAIB (All) AAIB (IDGA) DFDR Dual Engine Failure Engine Failure (All) FADEC Preliminary Report
2025-06-30T13:20:00
permalink Post: 11913619
If rigorously applied, an "engine thrust balancer" would cause the good engine to fail if something happened to the other one. Surely there is some logic in there somewhere to give up and disconnect past a certain amount of adjustment??
* as for why not before, probably because it didn't happen that way or in Boeing's worst nightmare some weird corner case in the software that does this if certain parameters are in rare combination.
* as for why not before, probably because it didn't happen that way or in Boeing's worst nightmare some weird corner case in the software that does this if certain parameters are in rare combination.
(As I don't fly the 787, I may be missing something basic on how the systems work).
Subjects: Parameters
2025-06-30T15:52:00
permalink Post: 11913718
Subjects: FAA
2025-06-30T19:08:00
permalink Post: 11913852
@Sailvi767, thank you for that video. Nice illustration.
About the previous video regarding Air India Flight 171: when Geoffrey Thomas said that "the aircraft appears to hover" at about time 2:00, I wondered at what kind of aviation expert he is supposed to be.
The aircraft was in forward flight once it left the ground, and until the flight ended (unless it stalled near the bitter end...FDR should clear that up in due course...but my guess is that it didn't stall even then).
It stopped climbing, sure, but it didn't hover.
Concur with the assessment of "clickbait"
About the previous video regarding Air India Flight 171: when Geoffrey Thomas said that "the aircraft appears to hover" at about time 2:00, I wondered at what kind of aviation expert he is supposed to be.
The aircraft was in forward flight once it left the ground, and until the flight ended (unless it stalled near the bitter end...FDR should clear that up in due course...but my guess is that it didn't stall even then).
It stopped climbing, sure, but it didn't hover.
Concur with the assessment of "clickbait"
Last edited by Lonewolf_50; 30th Jun 2025 at 19:18 .
Subjects: Self Proclaimed Experts
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