June 20, 2025, 21:43:00 GMT
permalink Post: 11907342
The question is moot because the likelihood of it happening is miniscule.
Subjects: None
June 21, 2025, 06:21:00 GMT
permalink Post: 11907519
The 787 is very wide, and the wing tips are pretty much at the edge of the paved surface; the vortex would extend beyond.
That's good info on the triangulation!
Subjects: None
June 21, 2025, 06:37:00 GMT
permalink Post: 11907526
Rotation location triangulated by Hoover
He analyses the point of rotation looking at the airport layout and using the video with the shack showing the aircraft rotate behind it, in that case the aircraft rotates at a reasonably normal place.
camera angle with shack and suggested point of rotation
camera angle with shack and suggested point of rotation
I like that we have a picture now, and that Hoover illustrates how he made the determination.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Pilot Debrief
June 21, 2025, 21:08:00 GMT
permalink Post: 11908056
Subjects: None
June 22, 2025, 07:24:00 GMT
permalink Post: 11908318
It's either 2 things....
1. That happens from time to time and its the way things are done in India and it's only newsworthy now by association (not causation), or
2. The DGCA need to be seen to be doing something, and that's some low hanging fruit in an otherwise vacuum of information.
1. That happens from time to time and its the way things are done in India and it's only newsworthy now by association (not causation), or
2. The DGCA need to be seen to be doing something, and that's some low hanging fruit in an otherwise vacuum of information.
It's a speculation, but I'd be surprised if it didn't fit the facts.
Also, we can't draw any conclusions about the accident crew; the discovery could've been incidental, or the accident crew might be affected, but the investigation is ongoing, so that's not public yet. It will be in the report, perhaps in the preliminary report even. (I expect NTSB and UK AAIB insist on a preliminary report, but who knows.)
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (UK) DGCA NTSB Preliminary Report
June 22, 2025, 07:33:00 GMT
permalink Post: 11908325
https://mode-s.org/1090mhz/content/ads-b/1-basics.html :
When the aircraft is on the ground (or on the water), it does not transmit altitude.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB
June 22, 2025, 10:34:00 GMT
permalink Post: 11908427
The Jeju recorders were okay if I recall correctly, they just had no input, was that the case?
Last edited by Musician; 22nd June 2025 at 11:12 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): DFDR EAFR MAYDAY RIPS
June 22, 2025, 11:04:00 GMT
permalink Post: 11908445
* all MCAS can do is affect the trim
* if something goes wrong with the trim, the crew works the "runaway trim" checklist
* this cuts MCAS off from the trim
* therefore, MCAS failure of any sort is going to be contained
It just turned out that if a crew is stuck, shortly after takeoff, in an aircraft that wants to go down, and they have no clue why because "AOA disagree" indicators are considered a luxury item for Boeing and Boeing also did not want to train crews for this, the crew may not be in the right mindset to prioritise that checklist.
Today, everyone is aware, so it's no longer an issue.
TCMA was motivated by a similar observation: that crews can fail to shut down an engine that no longer follows command input. So the FAA requires aircraft to detect that condition and do it automatically when on the ground, where an engine running at significant thrust is a danger to people and movable objects in the vicinity. The safety consideration here is, if you're on the ground and the thrust reverser is not deployed, you're not going to need the engine that badly. (I think there are actually two more conditions that I don't remember right now.)
In safety, you kinda need to weigh the consequences of having this system (with a chance that it might malfunction) vs not having it. Also consider that the benefit of having it, all of the occasions where it correctly shuts an engine off, don't get reported in the press.
If a TCMA bug caused this accident, the investigation will find out.
But right now, we don't have any evidence that that's what happened.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FAA
June 22, 2025, 11:41:00 GMT
permalink Post: 11908473
While impatient media might lament the delay, I think it is right that some time is spent on ensuring that the end result of the investigation is trustworthy. Even if that involves diplomacy.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): DFDR
June 22, 2025, 16:17:00 GMT
permalink Post: 11908653
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR
June 22, 2025, 16:20:00 GMT
permalink Post: 11908657
Whilst we wait for any announcements from the crash investigators can anybody suggest the logic behind providing the front mounted Enhanced Airborne Flight Recorders (EAFR) with a
Recorder Independent Power Supply (RIPS) but not giving the identical aft mounted EAFR unit the same protection where it is less likely to suffer damage?
Can you point to a single incident where this would have made a difference?
Another debate that should now be had is real time telemetry. Given the number of airlines contracting with Starlink for internet services onboard their fleets uploading the data stream fed to FDR's wouldn't put a dent on the available bandwidth and the search and recovery process for FDR's would be a thing of the past.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR DFDR EAFR RIPS
June 22, 2025, 18:23:00 GMT
permalink Post: 11908738
Musician: CVR Data
I think you will find that the cvr data is digitised before reachng the recorder, so that could be starlink as well. Can see that happening in the future, but the main obstacle to that is the cost of bandwidth and data storage. Significant to include all a/c in the sky at any given time, though the data could be compressed into packets, sent in batches.
I think you will find that the cvr data is digitised before reachng the recorder, so that could be starlink as well. Can see that happening in the future, but the main obstacle to that is the cost of bandwidth and data storage. Significant to include all a/c in the sky at any given time, though the data could be compressed into packets, sent in batches.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR
June 27, 2025, 04:23:00 GMT
permalink Post: 11911631
A few days ago, I created a "wiki post" at the top of this thread, where I hoped we could collect "must-read" information. If you don't have the requisite 90 days/90 posts to edit it, feel free to PM me with what you'd like to have added.
https://www.pprune.org/recentforumwikiposts.php
https://www.pprune.org/recentforumwikiposts.php
Subjects: None
June 30, 2025, 06:32:00 GMT
permalink Post: 11913383
Searching the web, I found out that regulations concerning new FDR require parameter 35g "fuel cut-off lever position" to be recorded. I also found that for a 2003 event with a 757, this was recorded (as was fuel flow).
I expect that this is also true for the 787. Can anyone confirm this?
I expect that this is also true for the 787. Can anyone confirm this?
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 Fuel Cutoff Switches
July 01, 2025, 05:56:00 GMT
permalink Post: 11914025
This is my latest attempt to square the circle using all the data points and minimal assumptions. The main shortcoming of the analysis is not knowing the maximum L/D and the speed for maximum LD with the gear down, flaps 5, and the RAT extended. However, if I use a reasonable number in my opinion for the L/D in that configuration and assume that the airplane is being flown at the speed for it, it will not get to the crash site. The distance from the runway of the crash site is from a previous graphic (1.55 km); the rotation point from fdr, permalink 314; 200 feet max height above the runway being generally accepted; crash site 50 feet below the runway elevation cited previously. An average speed of 180 knots is consistent with the dimensions given and 30 seconds flight time. A flare at 50 feet will briefly increase the L/D to 20, maybe even 30 (500 feet more than shown) but still not enough to make up the shortfall, In fact, with a head wind the L/D will be lower than assumed as well as if the speed being flown is higher or lower than required for maximum L/D in that configuration. In other words, there must have been some thrust available.
1) I had seen the "50 feet below runway" referenced as well, and double-checked on Google Earth, and could not confirm this. The terrain looks reasonably level. I'd be happy to see evidence for this claim, but until I do, I'll think it's false.
2) The maximum L/D is given for optimal speed, which remains constant throughout the glide. In the AI171 case, drag is balanced not just by loss of altitude (as it is in the optimal glide), but also by loss of speed. The speed decline provides energy, and I suspect that makes up the shortfall you assign to thrust.
Note that kinetic energy is proportional to v\xb2, i.e. a speed loss of 50 knots from 180 to 130 vs 50 to 0 provides 15500 vs 2500 units of energy, i.e. 6 times as much. If you hypothetically hurl a unpowered aircraft into the sky with a catapult (and if there was no drag), hurling it at 180 knots makes it go 6 times as high by the time its speed decays to 130 knots than it could ever go if you hurled it at 50 knots. Of course there's drag in reality, and that also varies with v\xb2, so this is a very theoretical consideration intended to calibrate your expectations.
I remember that someone used some kind of tool to confirm that the aircraft could've gone unpowered for as long as we assume it did, but of course I can't find it again now. :-(
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AI171 RAT (All) RAT (Deployment)
July 09, 2025, 13:09:00 GMT
permalink Post: 11918385
The idea is to set the switch to CUTOFF and then to ON as that resets the FADEC (the circuit that controls the engine) and hopefully clears any issues it might have. The hope is that the turbine is still rotating fast enough for the FADEC to restart it. I believe this works the same as the auto-relight feature.
The turbine rotation would also provide the electrical power for that.
Do a thread search on "detent" to learn more about the construction of these switches than you ever wanted to know.
There's also a section on them in paulross 's https://paulross.github.io/pprune-th...171/index.html , but it may not be up to date. (Still a great resource, though.)
Unfortunately the wikipost linking to it is gone, presumably a victim to the recent forum changes.
The turbine rotation would also provide the electrical power for that.
Do a thread search on "detent" to learn more about the construction of these switches than you ever wanted to know.
There's also a section on them in paulross 's https://paulross.github.io/pprune-th...171/index.html , but it may not be up to date. (Still a great resource, though.)
Unfortunately the wikipost linking to it is gone, presumably a victim to the recent forum changes.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FADEC Fuel (All) Fuel Cutoff Switches Fuel Cutoff Switches (detent) RUN/CUTOFF Relight
July 09, 2025, 14:58:00 GMT
permalink Post: 11918444
What are you talking about? Sources have already leaked information. NTSB (USA), AAIB (UK) and ICAO have sent people who have access, not to mention the aircraft and engine manufacturers. There's going to be a final report in about a year, and when that's out you can complain. (There has been precedent for a national accident board making a release about an investigation when the official report came up short, but I don't remember the details.) The ICAO-prescribed process is designed to produce this kind of participation, because air safety can't be a political issue.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) ICAO NTSB
July 09, 2025, 15:09:00 GMT
permalink Post: 11918452
If the switches were operated before the power went out, that's logged on the flight recorder.
It's possible that the CVR would record a pilot calling out as he operated the switches, though.
Last edited by Musician; 9th July 2025 at 15:48 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR DFDR
July 09, 2025, 15:37:00 GMT
permalink Post: 11918467
I've seen a quote saying, "In accordance with international protocols, release of information on the air crash probe rests solely with the Indian authorities." This means that while there are other parties to the investigation, India's AAIB has the final say over what goes in these reports, in accordance with Annex 13. But ICAO would not say that India has the option not to release a report.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) Annex 13 ICAO Preliminary Report
July 09, 2025, 16:47:00 GMT
permalink Post: 11918516
Theory alert : If you don\x92t have, or delete the cruise altitude in the FMC the aircraft will command a level off at 400ft, with the thrust levers reducing thrust significantly. It\x92s easy to do when loading the descent winds if you hit the wrong button. Could this have been confused with a loss of thrust?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CCTV