Posts by user "Gupeg" [Posts: 13 Total up-votes: 0 Pages: 1]

Gupeg
June 15, 2025, 02:11:00 GMT
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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
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Post: 11902623
Originally Posted by NOC40
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)
If you wanted to an analyse this further:
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
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Post: 11902634
Originally Posted by DaveReidUK
They are groundspeeds.
Thanks for that... makes the energy analysis more accurate/relevant

Subjects: None

Gupeg
June 30, 2025, 01:48:00 GMT
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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
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Post: 11913998
787 Fuel System

Originally Posted by Sailvi767
Both engines run from the center tank on takeoff if it has fuel in the tank which was the case on this flight.
It would be good to get an FCOM reference for this, and/or definitive answer from a current 787 pilot (if they know ).

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:
  1. Actually running on takeoff?
  2. If running, they are providing centre tank fuel directly to both engines, and not, say, centre tank fuel to wing tanks, and then wing tanks to engines?

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
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Post: 11920329
Originally Posted by Saab Dastard
(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.
The Mods have stuck to this principle, which I shall try to adhere to.
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
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Post: 11920757
Originally Posted by za9ra22
...
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.
With all due respect I disagree I think the prelim report was very sanitised to achieve the aim of a prelim report (are there any urgent safety actions relevant to this accident to be addressed?) whilst avoiding 1) Extreme public reaction 2) Addressing potential criminal behaviour - which the AAIBs are not experts in, nor the correct investigatory authority.
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
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Post: 11921303
Originally Posted by LTC8K6
Remember that engine 1 had actually relit and began to recover and engine 2 had also relit.
To me it's amazing that those big engines were able to do that in the time allotted.
I'm not sure it is amazing? All I read into the report's words is that the FCSs were turned on, I assume that this will see fuel flow to the combustion chambers and ignitors within 1s, and if the fuel ignites (why not?) EGT rises and the report records this as "relit".
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).

Originally Posted by LTC8K6
Why would a suicidal pilot even allow the attempt to restart within 10 seconds?
As a wild guess, if he knew it would not succeed (and it true, was correct and recovery was not even close to being possible)

Originally Posted by LTC8K6
Why wouldn't he yell out the other pilot's name and ask "What are you doing?" for the CVR theater performance?
To be frank, we do not know he did not. The report has been (IMHO) carefully sanitised to remove any evidence indicating it was (or not) a suicide attempt, which pilot said what, when they said it, no indication these were the exact words, and no indication that there is not plenty more conversation available.

If we want to speculate in this area, one could ask (my best guess):
  1. Do the AAIB know who said "why" and who "I did not"? (Yes)
  2. Are they the exact words? (No) Or a 'summary'? (Yes)
  3. Were other words spoken by one of both pilots? (Yes)
  4. Do the AAIB know whether there were or were not other cockpit occupants? (Yes) Were there? (No - since to fail to mention it casts assertions on just 2 named individuals)
  5. Are the AAIB fairly certain of the root cause of this accident (Yes i.e. mechanical issue, unintentional HF, unlawful interference) If yes, have the AAIB deliberately sanitised this report to conceal both the root cause, and other information that would lead to uninformed speculation that does not further flight safety (Yes)

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
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Post: 11921617
Quote: Originally Posted by Contact Approach
But there is evidence, pretty clear evidence!
Originally Posted by OldnGrounded
Is there? Is there evidence for the scenario that you have endorsed, that the Captain deliberately, intending to crash the airplane, moved the fuel control switches to CUTOFF and then accused the FO of doing that? What is that evidence?
The "evidence" might be available, but I disagree it is available to us. I assert the prelim report has been deliberately sanitised to prevent us (i.e. everybody outside the AAIB circle) being given enough 'evidence' to make certain conclusions.

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
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Post: 11921971
Originally Posted by directsosij
what is the big deal about flight deck cameras? if it is treated the same way as the FDR then what is the problem?
For historical reasons, adding CVRs (Voice/Audio) to aircraft was a controversial subject. I think there was a particular accident that led to their introduction, but involved the 'buy-in' from pilot's unions, who were able to play their part in the legislation and installation. For instance, each cockpit (at least until 10 years ago) has a CVR erase button.
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.
i.e. the 787 EAFRs appear to have the crash protected ability to record images/video, but not (yet?) the cameras etc. to do it.

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
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Post: 11922163
Originally Posted by slats11
One pilot leaving the cockpit (we believe) and the act of switching off communications would have been streamed. That may (I say may) have provided sufficient deterrence.
Sorry - disagree. Even with FDRs and CVRs, pilots are ultimately controlling the aircraft, including power to the CVR/FDR etc (and CVR erase).
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
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Post: 11922431
Originally Posted by OPENDOOR
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.
There is a huge difference between Starlink letting the SLF watch videos and WhatsApp their mates, and using it to stream regulated data... in the latter case, once mandated, whenever Starlink has a glitch, or cannot logon, the flight is grounded.
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
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Post: 11922470
Originally Posted by MechEngr
The proposal is to -also- stream to Starlink or the equivalent. No need for grounding for an optional accident investigation data stream that in no way affects safety of flight.
If it is optional, no airline will install it. Nil advantages - they have long had QAR data to review post flight. Before you say "live data" is an advantage, no pilot went into management to monitor flights real time at night, weekends or holidays

Subjects: None