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Gupeg
June 15, 2025, 02:11:00 GMT permalink Post: 11902052 |
Re FDR and CVR, remember the 787 uses EAFR(s) instead - one in tail and one in nose.
Comments above "they will already have been read" - suggest search and read India press links, and the (new) India AAIB lab ability to read data recorders, e.g. one timed at June 15, 2025 00:08 IST. It may well be the first 'political' issue about this accident in where the recorders are sent. If India is chosen, maybe they will take their time with a new lab, and watched over by the world and other AIB representatives? I believe the investigating state 'controls the release of information' (or not). Whilst the UK AAIB are there, as their website says they have 'expert' status, which I suspect means not a lot of involvement in the politics. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (UK) CVR FDR |
Gupeg
June 15, 2025, 16:46:00 GMT permalink Post: 11902623 |
Flightradar24 (I know, I know) has a short blog on the (very minimal) ADS-B data available. There's only around 4s of useful data available from 21ft o 71ft altitude (last packet received 0.8s later), But: it's odd seeing the speed DROPPING shortly after takeoff. Even if you calculate total energy (kinetic + potential) it's falling, i.e. the engines aren't producing thrust. (In fairness reported speed doesn't match my calculated speeds, but even with mine I don't see power). Also: if you assumed no thrust from 71ft AGL @ 172kt you'd reach 250ft at 160kt. Isn't that roughly where they ended up? Noisy data, but this suggests the engines stopped producing power almost as soon as the wheels left the ground. (If someone could download a CSV of another similar flight and send to me I can do a compare and contrast of Total Energy)
1. You might mathematically start at TE=0 at start of takeoff-roll, and treat drag as minimal until rotation. 2. Typically rotation will be to say 15deg nose up, but flight path will be much less (5deg? for heavy hot 787). Once that rotation is complete, aircraft will stop accelerating. Therefore engine thrust (energy gain) equals gain in PE - drag x time. 3. This might give a better insight into where energy gain/loss became unusual? Looking at the raw data in your post, and given the speeds are likely IAS based i.e. can be affected by wind, I don't see the IAS loss as equating to dual engine failure i.e. zero thrust - but could be wrong. Once a heavy airliner gets to lift off the acceleration is reduced (drag) and the decays to zero as PE gain kicks in. Ditto a time / distance to the crash site might give some energy info? Looks like the crash site is 50' (?) below the airfield (Google Earth will give more). I think you are doing an interesting study on the absence of other info ![]() Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB Dual Engine Failure Engine Failure (All) FlightRadar24 |
Gupeg
June 15, 2025, 17:01:00 GMT permalink Post: 11902634 |
Subjects: None |
Gupeg
June 30, 2025, 01:48:00 GMT permalink Post: 11913321 |
As per T28B but expanding:
Part 1: Fly the aircraft in Pitch such that ground impact occurred at minimum IAS compatible with minimum RoD. If 120KIAS is stall speed, roughly 130KIAS at zero RoD. Part 2: Fly the aircraft in Roll such that the distance flown from Part 1 was the least hazardous to aircraft occupants and people on the ground. Given the starting conditions I doubt if more than 10AoB would be practical? Part 3: Try and do whatever to restore thrust. At a guess Part 1 was attempted, Part 2 was hardly a choice to achieve much and Part 3 needs to await the investigation, but I surmise little could or was done. Subjects: None |
Gupeg
July 01, 2025, 03:07:00 GMT permalink Post: 11913998 |
787 Fuel System
![]() On the A320 if the centre fuel pumps are selected on pre-start, they run for 2 mins after start and then turn themselves off until Flaps selected to 0 (i.e. well after takeoff), when they turn themselves on. As far as the crew are concerned they were selected on from pre-start onwards [long retired A320 so forgive me if in error]. If certification demands this 'complexity' it would seem surprising the 787 does not have a similar system? Are we sure the 787 centre tank 'higher pressure' pumps are:
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Centre Tank FCOM Fuel (All) |
Gupeg
July 12, 2025, 08:15:00 GMT permalink Post: 11920329 |
(Admin/Mod)Folks, it appears that the message isn't getting through.
There were two professional pilots on that flight deck. It is not acceptable to effectively accuse both of a criminal act, because there is no evidence to identify which hand - if either - moved the fuel switches, or for what purpose or reason. Unless and until any such evidence is published by the relevant authorities, kindly desist from doing so out of respect for your professional colleagues. This preliminary report is just that, but maybe consider the issues the Indian AAIB have had to address in publishing it. They will have a similar concern to the pP mods, maybe more so since any apparent accusations directed at the pilots may lead to physical retribution. I therefore conclude great care has been taken to "sanitise" what the AAIB know, or at least strongly suspect, (from EAFR) into the report. They have conspicuously failed to identify which of the pilots was each half of the conversation they have not repeated the exact words, there's a lot missing (was positive rate ever called, was rotate ever called, any discussion about putting FC back to Run, who/how flying aircraft meanwhile). As a result we, the reader, should step back and not over-interpret this sanitised report. Secondly, given the mod statement above, if a criminal act is suspected by the AAIB, this will likely trigger all sorts of 'primacy' issues in the investigation i.e. police? AAIB? or joint? and all the history that involves (SAS Linate?) - in Europe we have 996-2010 Article 12 para 2, but India? Summary : For good reason I believe this report has been very carefully worded, sanitised with great care, and as such easy to inappropriately speculate what went on. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (India) EAFR Fuel (All) Fuel Cutoff Switches Preliminary Report Thread Moderation |
Gupeg
July 12, 2025, 19:01:00 GMT permalink Post: 11920757 |
...
On edit: and No, I doubt the preliminary report was written to avoid the risk of copycat actions or delay public reaction. The investigatory team are not at all likely to be considering that kind of audience in what is essentially a finding of fact. An altercation would have been caught on the CVR... and reported upon. ![]() Your final sentence similarly I doubt - I suspect the CVR does reveal a lot more - certainly the timings of the reported interactions. It's just sensitive information... The report was written at 4AM ish Indian time and released shortly afterwards, and I surmise most of the delay was not "what to include" but "what NOT to include" to (only) achieve the aims of a prelim report. I am not trying to be disrespectful, just put forward a different point of view, and you may well be right... Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR Preliminary Report |
Gupeg
July 13, 2025, 12:59:00 GMT permalink Post: 11921303 |
The low airspeed airflow through engine and HP RPM on Eng 1 were sufficient to allow HP RPM to increase. The longer delay between Eng 2 OFF then ON allowed HP RPM to decay more than #1, and although 'relit', I read a successful (unassisted) spool up was unlikely? (i.e. a detailed unassisted relight envelope including current HP RPM and IAS would have #1 in the envelope and #2 outside). If we want to speculate in this area, one could ask (my best guess):
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) CVR Fuel (All) Relight |
Gupeg
July 13, 2025, 20:27:00 GMT permalink Post: 11921617 |
Quote: Originally Posted by
Contact Approach
But there is evidence, pretty clear evidence! You/others might not like it, some might say it is obvious (I say not), but I think it is carefully worded enough to imply what might have happened, but nothing is clear - intentionally. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) Fuel (All) Fuel Cutoff Switches Preliminary Report RUN/CUTOFF |
Gupeg
July 14, 2025, 08:50:00 GMT permalink Post: 11921971 |
Recording images/videos is prevented by similar union/regulator agreements AFAIK . It might take this accident to change that, of note the GE EAFR fitted to the 787 has the capability:
The EAFR is capable of providing combinations of any or all of the mandatory crash protected recorder functions in a single Line Replaceable Unit (LRU). The EAFR functions include the Digital Flight Data Recorder (DFDR) function, the Cockpit Voice Recorder (CVR) function, the Data Link recording function,
and Image Recording function growth
Includes growth for Image recording (5 Gigabytes Crash Protected Memory) . The Image Recorder growth function is used to record visual images of the flight deck instruments, flight deck, the aircraft structures, and engines as required. The Image Recorder function is capable of receiving a digital 10/100 Mbit Ethernet data stream of cockpit images and stores this data in the Crash Protected Memory in a separate partition. Even though the image recording duration will be governed by regulations , the EAFR Crash Protected Memory capacity has the storage capacity for two hours of image data recording per EUROCAE ED-112 requirements. Data in the Image Recording Crash Protected Memory partition can only be downloaded when the EAFR is off the aircraft. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR DFDR EAFR FDR |
Gupeg
July 14, 2025, 12:35:00 GMT permalink Post: 11922163 |
You seem to be advocating a "pilot proof" recording and streaming system in real time? Whilst possible, it is a big step from today, and even if the regulators / airlines / unions agreed, it would be a long time before all aircraft flying were fitted. The current systems are designed for accident investigations, not unlawful interference by pilots. The cockpit door again is designed for unlawful interference by others than the crew (including cabin crew), and despite Germanwings and maybe MH370 (where the door was used by the crew unlawfully enabling the accident), no changes have (to my knowledge) been proposed. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR |
Gupeg
July 14, 2025, 18:55:00 GMT permalink Post: 11922431 |
A few years ago I'd have agreed with you but with many airlines now installing Starlink terminals on their fleet it is a relatively tiny amount of data to add.
There is no reason the data stream fed to the FDR's couldn't also be encrypted and sent to the operator for long term storage. It might prove very useful and not just after accidents. Of the 5 flights I have done where the carrier advertises me a sort of WiFi service, on 3 it has never worked, one I got to send a few messages then no more and on one it was sort of useful, some of the time... Subjects: None |
Gupeg
July 14, 2025, 20:10:00 GMT permalink Post: 11922470 |
![]() Subjects: None |
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