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| Xeptu
June 13, 2025, 10:14:00 GMT permalink Post: 11900293 |
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB FlightRadar24 MAYDAY |
| Xeptu
June 13, 2025, 11:53:00 GMT permalink Post: 11900411 |
Assumptions
30 secs to 100 kts from TO power set.and 200 kts after 60 seconds Impact occurred 30 secs after Vr 1 nm out, so about 120 kts and no more than 300ft The gear was not or could not be retracted. Without doubt the crew knew impact was inevitable at least 10 seconds prior to impact noted by body angle change in video evidence whether a Mayday Call was in fact made or not. I think that the only thing that would matter for any of us in that 20 seconds would be THRUST and everything it's got. Which occurred first, the loss of thrust on both engines causing all generators to go offline or a total electrical failure that caused flight Idle thrust. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Electrical Failure Generators/Alternators MAYDAY |
| Xeptu
June 13, 2025, 13:18:00 GMT permalink Post: 11900511 |
Out of interest about when did the RAT include a hydraulic pump, not that it would be sufficient to retract the gear anyway. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Generators/Alternators Hydraulic Failure (All) RAT (All) |
| Xeptu
June 13, 2025, 13:50:00 GMT permalink Post: 11900540 |
I think flap setting for takeoff is not in the equation because the aircraft became airborne and was seen in the video climbing away, the takeoff is over.
retracting the flap instead of the gear is a high possibility, yes there would be sink but the aircraft would still be accelerating, distance over time says an impact speed of about 120 kts. where it would have been 200 kts in this scenario. I also think it would be unmistakeable to those on the ground if the engines were at go around thrust at impact. Subjects: None |
| Xeptu
June 14, 2025, 03:06:00 GMT permalink Post: 11901102 |
Nose down would be to get best glide - longest time in the air and max distance. Raising the nose up leads to a stall and brings the aircraft down faster than best glide. It's counter-intuitive, hence the tendency to pull the nose up in a stall or loss of power has to be trained out of pilots.
Subjects: None |
| Xeptu
June 15, 2025, 01:53:00 GMT permalink Post: 11902043 |
Also a newcomer here, but an experienced private pilot, Software Engineer with a degree in Aerospace Computer Science and former Head of Quality for Satellites and Interplanetary Missions. We have already seen bad software solutions and the results thereof in the 737 MAX accidents, which makes me wonder, if the TCMA can reach a state, where unintended engine shutdown is possible.
There is one system implemented in the 787, that has the authority to shut down the engines, based on software subsystem decision. Interestingly - according to the description in the patent below - the same TCMA software package determines the shutdown decision, in both redundant subsystems. Excerpt from the Patent: "Malfunctions in aircraft power plant thrust control systems can result in uncontrollable high engine power levels that are potentially hazardous or catastrophic for aircraft operation. A particularly hazardous situation is when a thrust control system failure results in one of the aircraft's engines continuing to operate at a high power condition and not responding to a throttle command to reduce power during takeoff, approach or landing. Typically, when this failure mode occurs, the actual thrust either increases to a significantly higher than commanded thrust and/or remains at a high level when the thrust levers are set for low thrust.... In one preferred embodiment the present invention is directed to a system and method for detecting and correcting a thrust control malfunction in an aircraft engine. The system includes an electronic engine control (EEC) unit that includes a first processing subsystem and a second processing subsystem, and a thrust control malfunction accommodation (TCMA) circuit included in the first processing subsystem and the second processing subsystem. Additionally, the system includes a TCMA software package executed by the first processing subsystem and the second processing subsystem, thereby providing redundant execution of the TCMA software package. The method of the present invention compares the engine's actual power level with a threshold contour defined by the TCMA software package. When the TCMA software package determines that a thrust control malfunction has occurred, based on the engine's power level exceeding the threshold contour, the engine is shut down by the TCMA circuit. The present invention is still further directed to an electronic engine control (EEC) unit configured to detect and correct an aircraft engine thrust control malfunction using an active-active functionality. The EEC includes a first processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs, and a second processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs." Just my 20 cents Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Engine Failure (All) Engine Shutdown V1 |
| Xeptu
June 15, 2025, 02:57:00 GMT permalink Post: 11902067 |
Sorry about that. The reply was aimed at the OP. from a software writers perspective, as you rightly point out it does not imply an electrical event actually occurred. As you raised that query writing software routines (programming) is no different and that's what we're looking for.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): V1 |
| Xeptu
June 15, 2025, 10:28:00 GMT permalink Post: 11902330 |
Are we all forgetting the fact that the gear did not retract and so therefore didn't make it into the second segment, did it make it to 400 feet, probably not, regardless of what happened next whether the engines rolled back/stopped or some other butt squeezing distraction, there is only 15 seconds to impact remaining.
Now what was the crew doing, the same as any other crew maybe max thrust but mostly just waiting for impact, despite what you think you would do that's pretty much how it pans out in the sim too. Subjects: None |
| Xeptu
June 16, 2025, 06:59:00 GMT permalink Post: 11903160 |
Subjects: None |
| Xeptu
June 17, 2025, 13:12:00 GMT permalink Post: 11904292 |
Subjects: None |
| Xeptu
June 17, 2025, 14:39:00 GMT permalink Post: 11904356 |
Subjects: None |
| Xeptu
June 17, 2025, 15:39:00 GMT permalink Post: 11904404 |
There are several videos of the survivor being interviewed in India, all of them as one might expect, in the language of the country, with English subtitles. As Mr Ramesh is a British national, many years in the UK, I did wonder if there have been any interviews in English, in which I expect he is fluent. That might/should eliminate errors in translation and make his testimony more clear. I can't find any on the net.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Engine Failure (All) |
| Xeptu
June 18, 2025, 04:28:00 GMT permalink Post: 11904891 |
Thankyou I didn't know that and I'm not questioning you. I guess it doesn't matter electrically driven or engine driven, they cannot share the same power supply the gear must be retracted within 12 seconds. this in my opinion improves the argument for total electrical failure. Unless of course gear up was never selected..There must also have been a substantial loss of thrust on at least one engine.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Electrical Failure Hydraulic Failure (All) |
| Xeptu
June 18, 2025, 23:09:00 GMT permalink Post: 11905607 |
I need to correct one of my previous posts, I was going down the path of a mismanaged engine failure after V1, however it's been demonstrated to me that this aircraft will fly away on one engine even with the gear down with better than minimum climb gradient requirement. Quite astonishing actually.
That just leaves deliberate act not necessarily intentional, fuel vapour lock and automatically commanded engine shutdown. I hope the rat is found soon so we know for sure if both engines were in fact lost. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Engine Failure (All) Engine Shutdown V1 |
| Xeptu
June 19, 2025, 12:57:00 GMT permalink Post: 11906003 |
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 |
| Xeptu
June 20, 2025, 23:34:00 GMT permalink Post: 11907393 |
It sure is a head scratcher and when you think you're on the right track "BOOM"
I'm of the view that this was most likely a commanded shutdown of both engines that occurred at or between liftoff and gear up selection. That in the case of automatically that the conditions on the list of criteria were met and that one or more of those conditions was in opposite sense, weight on wheels would most likley be one of them. I believe that in at least the first 10 seconds from Vr the crew would have continued to do exactly what they were trained to do without deviation. For example Both Engines at Takeoff Thrust TL Position, Thrust Command, unknown or last known flight idle Gear Selector, Overriden UP Last edited by Xeptu; 21st June 2025 at 01:37 . Reason: extended Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Weight on Wheels |
| Xeptu
June 21, 2025, 22:20:00 GMT permalink Post: 11908113 |
So when people say "the FADEC software" (ie TCMA) has "failed" or "has a bug" what they're really saying is:
The conditions that were experienced in the real world by the system were incorrectly assessed in the system requirements and lead to an undesired output state when taking into account the real world result we would have preferred.
A bit of a mouth full, granted, but an important mouth full. This simply wouldn't be someone missing a semicolon somewhere in a thousand lines of code.
Regards, Justus Truth Table Line 101 = Service Terminated (licence agreement expired please contact your service provider) Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FADEC |
| Xeptu
July 12, 2025, 02:26:00 GMT permalink Post: 11920106 |
Regardless of how this happened I find it perplexing that a switch with such consequence in either position can be operated with a flick of the wrist.
Firewall shutoff switches are guarded, fire bottle switches are guarded or require both hands to operate, all require two deliberate actions to operate, except two switches in the middle of the console which do so many consrquential things.. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Switch Guards |
| Xeptu
July 12, 2025, 03:42:00 GMT permalink Post: 11920149 |
Ok, I use these switches today, you pull it out against spring pressure, move to opposite position and let go, the spring load snaps it back into position. Like a semi circle motion. When you have used them a few times like I have, I would describe ithat motion as a flick of the wrist. Is that a better explanation.
Subjects: None |
| Xeptu
July 12, 2025, 03:55:00 GMT permalink Post: 11920158 |
Again I agree with you, 3 seconds is about right for positive rate, I would be starting to lean over toward the gear handle about then. So did the start switches manually move to shutoff or not, if not then, they must have been manually cycled off to run 10 seconds later and what raised the "why did you" query, wouldn't that query be "dual engine failure"
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Dual Engine Failure Engine Failure (All) |