Posts about: "DFDR" [Posts: 81 Pages: 5]

John Marsh
June 19, 2025, 15:06:00 GMT
permalink
Post: 11906098
Flight recorders

Reuters :
The government said in a statement that the decision on where the decoding of the recorders would take place would be made after India's Aircraft Accident Investigation Bureau (AAIB) has made a "due assessment" of all technical, safety and security considerations.

AAIB's Director General GVG Yugandhar told Reuters earlier in an emailed response that the Economic Times report was "factually incorrect", but gave no further details.

The government statement did not explicitly rule out the possibility of the flight recorders being sent to the United States.

It asked for people not to speculate on what it called sensitive matters and stressed the crash probe was progressing with all necessary support from local authorities and agencies.
rigoschris
June 19, 2025, 16:54:00 GMT
permalink
Post: 11906193
Originally Posted by mh370rip
SLF Engineer(electrical -not aerospace) so no specialised knowledge of any kind.
The TCMA discussions on here seem clear that in normal operation the TCMA functions should not
operate in air mode and the TCMA has multiple inputs from various sensors (Rad alts, WOW sensors).
My query is to how these signals are routed to the engines, are they compared/aggregated in or routed through
the EE bays. If they are present in the EE bays then fdr's idea of a water leak at rotate into the EE bays
could generate shorts from the HV buses to the TCMA units.
Are the TCMA units designed to cope with 400V AC inputs where a low voltage input is expected.
I appreciate that the TCMA has to physically power a valve closed but applying high voltage to low voltage
logic circuitry might have unexpected consequences.
The TCMA runs on the FADECs (Full Authority Digital Engine Control). There is one per engine, located inside the nacelle. Each one has a dual channel design inside, to compare computations, inputs etc. and generally provide redundancy (but I don\x92t know further details on the design/logic).

The sensors and actuators related to that engine (pressure, temperature sensors, various valves etc.) are most likely directly connected to it. The two throttle position sensors per engine are also directly cabled to it according to tdracer. No idea how other inputs like WoW and RADALT are connected. The FADECs don\x92t necessarily need much else, as apparently Autopilot etc. always move the actual thrust lever.

There must also be a communication channel back to the flight recorders. No idea if it gets thrown into a comms bus or there is direct wiring.

In terms of power, each FADEC has its own alternator driven by the engine. But there\x92s a failover connection to the AC bus of the plane. Not sure if there\x92s a physical relay keeping it disconnected in normal operations.
jdaley
June 19, 2025, 20:35:00 GMT
permalink
Post: 11906349
slf/ppl here - with a respectable amount of experience in software delivery for real-time/embedded/safety critical systems. Software development in this area really is an engineering discipline and bears no resemblance to common practice in other areas. Couple that with the requirements for function duplication/triplication, harness separation et al then IMHO the chances of FADEC etc software errors are effectively zero.


I'm commenting to make that point but also to link the videos and the FR-24 dataset - (below with my deltas for height/time added)



Extract from FR24 csv dataset


As noted in both threads to date everything was normal until it wasn't - the two values for fpm above are subject to FR24 variance of +/- 25' so even these suggest a normal climb at this stage of flight ca 2,000fpm. FR24 Lat/Longs all follow the centre line.


On this data the climb stops at around 70' AGL and electrical failure around 2s later. Again, as noted in the threads, this aligns with when gear up might have been expected. If the climb stopped because of fuel shutoff then 2s for spool down to electrical failure isn't out of the question.


Looking at the two videos.

The CCTV video indicates a total flight time, from rotation, of about 32s, subjectively levelling off ~14s after rotation.

The rooftop video has a flight time ~14s suggesting the video starts ~18s after rotation.


The rooftop video evidences the RAT as deployed from the beginning - meaning it must have been deployed by at least 16s after rotation - which aligns with the ADS-B indicated electrical failure.


If the forward flight recorder really is being sent to the US for recovery then it's reasonable to assume that the rear recorder contains nothing after the electrical failure and they are hoping the forward recorder captured something from the cockpit in the final 16s.


I don't have any experience of flight deck CRM but I don't see how those timings allow problem identification/misidentification and subsequent action - ie it wasn't down to the crew.


However:

The maximum aircraft height in the CCTV video, as judged by wingspan, appears higher than 71' - though it is certainly less than a wingspan height at the beginning of the rooftop video.


I haven't seen, in the threads, any statement of what happens on the flight deck with a total electrical failure - is it a 4s blackout whilst the RAT deploys and systems restart? - or are there batteries that keep something alive?
thf
June 20, 2025, 14:21:00 GMT
permalink
Post: 11907014
Background info from "The Hindu", Ahmedabad plane crash: Aircraft Accident Investigation Bureau yet to decide where black box data will be decoded

Black Boxes
The government body investigating the Air India Boeing 787-8 crash in Ahmedabad last week will take a decision on where the black box data will be decoded \x93after due assessment of all technical, safety, and security considerations,\x94 the Ministry of Civil Aviation said on Thursday (June 19, 2025).

The statement said two different sets of black boxes were recovered from the crash site, one on June 13 and another on June 16. Each black box unit comprises the Digital Flight Data Recorder (DFDR) and Cockpit Voice Recorder (CVR).
Preliminary Report
A government official closely involved with the probe said there would be a preliminary report. Interestingly, during the only other airline crash investigated by the AAIB (which was formed in 2012), after the Mangalore crash of May 2010 \x97 i.e. Calicut accident \x97 only the final report was published within a year.

Officials, past and present, explained that the rules under which the AAIB carries out an investigation do not specify a timeline for a preliminary report, even though the UN aviation safety watchdog, the International Civil Aviation Organisation\x92s Annex 13 requires one within 30 days. A similar rule is not part of the Aircraft (Investigation of Accidents and Incidents) Rules, 2017 formed under the principal law, the Bharatiya Vayuyan Vidheyak, 2024.
(...)
One of the above mentioned officials said the Calicut probe team didn\x92t release a preliminary report because the Rules don\x92t lay down a timeline for it and require such a report to only categorise the nature of the mishap. He added that the team involved in the drafting of the Rules held the opinion that such a report could be vastly different from the final investigation report, which may result in public criticism and media backlash.
AirScotia
June 21, 2025, 13:57:00 GMT
permalink
Post: 11907776
The situation with reading the flight recorders seem increasingly suspicious to me. As of yesterday, they're still dithering about whether to send them to the USA? Is this about India not wanting to reveal their smart new facility can't do the job? Or unwillingness to trust the US/Boeing? Or some other kind of argument? It seems ridiculous to me that no decision has been made about the boxes nine days after the crash and the rapidly discovered recorders.

India to decide on overseas analysis of Air India crash flight recorders
T28B
June 21, 2025, 14:05:00 GMT
permalink
Post: 11907781
Originally Posted by AirScotia
The situation with reading the flight recorders seem increasingly suspicious to me. As of yesterday, they're still dithering about whether to send them to the USA? Is this about India not wanting to reveal their smart new facility can't do the job? Or unwillingness to trust the US/Boeing? Or some other kind of argument? It seems ridiculous to me that no decision has been made about the boxes nine days after the crash and the rapidly discovered recorders.

India to decide on overseas analysis of Air India crash flight recorders
I am not from India, nor associated with this investigation.
Note this excerpt from your linked article:
India's Aircraft Accident Investigation Bureau (AAIB) is yet to decide whether flight data and cockpit voice recorders from the Air India flight that crashed last Thursday will be sent overseas for decoding and analysis. {remove crash generalities} Some media outlets reported that the black boxes are being sent abroad, but the ministry of civil aviation clarified that no final decision has been made.The ministry said the AAIB will determine the location for analysis after a "due assessment of technical, safety, and security factors".
I will defend their investigating team, and the release of information time line, based on at least these points:
1. They'd rather do things deliberately, and get it right, than to make a slight rush and get something wrong (even a little bit wrong)
2. The political leadership are sensitive to how the information age, and social media, amplifies even the slightest misstatement.
3. If they can do it in house then why not do it in house? Why add further delay by transferring the recorder and risk accidents in handling during transit?
4. They are under a timeline set by ICAO, not the time line that your, or my, or "the public's" hunger for information and impatience sets.

Let's give them the benefit of the doubt.

Last edited by T28B; 21st June 2025 at 14:13 . Reason: punctuation errors
OPENDOOR
June 21, 2025, 15:29:00 GMT
permalink
Post: 11907844
787 EAFR unit

The Enhanced Airborne Flight Recorder (EAFR) fitted in the forward and aft locations are interchangeable and appear to be able to record video.

As their power requirements are 28 VDC and just 20.5 watts it seems strange that only the forward mounted unit should have a battery backup.

T he 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.
https://www.geaerospace.com/sites/de...rder-3254F.pdf
Musician
June 22, 2025, 10:34:00 GMT
permalink
Post: 11908427
Originally Posted by Icarus2001
Always possible, however since a pilot made a radio call there was some emergency leve l power available, which suggests the EAFR would be powered.
VHF L is on emergency power, the EAFR are not ( see Air India Ahmedabad accident 12th June 2025 Part 2 ). The front EAFR has its own battery (RIPS) for that reason, the back EAFR has not. (The number of 787 events where this mattered is zero so far.)
The Jeju recorders were okay if I recall correctly, they just had no input, was that the case?
Different (older) aircraft, the flight recorders there did not have backup power iirc.

Last edited by Musician; 22nd June 2025 at 11:12 .
Musician
June 22, 2025, 11:41:00 GMT
permalink
Post: 11908473
Originally Posted by DIBO
in my first reply, I started typing, but then removed, 'one thing missing in the FDR's disaster survivability requirements, is 'politics resistance'. Not implying that in this case, except for some face saving moves, the 'thruth' is in danger.
I had thought consideration for the preservation of truth might underlie India's reluctance to send the flight recorders across the Pacific Ocean. But it could simply be that the foreign accident boards and India have different opinions on how trustworthy India's flight recorder lab is. Negotiations ensue? Anyway, this is idle speculation on my part.

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.

OPENDOOR
June 22, 2025, 14:57:00 GMT
permalink
Post: 11908601
Enhanced Airborne Flight Recorders (EAFR)

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?

The RIPS unit is a certificated device that just has to supply 20.5 watts for ten minutes so cost cannot be a consideration.

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.

quentinc
June 22, 2025, 15:21:00 GMT
permalink
Post: 11908618
Originally Posted by OPENDOOR
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?

The RIPS unit is a certificated device that just has to supply 20.5 watts for ten minutes so cost cannot be a consideration.

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.
The RIPS provides power to both the recorder and to the microphones in the cockpit.... If there's no power to the microphones, there is nothing to hear. If there's no power for systems in the aircraft.... then there's not going to be much for any recorder to record.
Musician
June 22, 2025, 16:20:00 GMT
permalink
Post: 11908657
Originally Posted by OPENDOOR
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.
You'd still have to search for the CVR, so...
za9ra22
June 22, 2025, 18:25:00 GMT
permalink
Post: 11908740
Two minor points regarding competence and who gets the task of data extraction from the data recorders: Firstly, that it's the AAIB (India) which will decide where and when to hand over the data recorders, and secondly, the supposed comment attributed to the Ministry of Civil Aviation in the press release dated June 19 ( https://www.pib.gov.in/PressReleaseP...x?PRID=2137718 ), that "t he decision regarding the location for decoding the flight recorders will be taken by the AAIB after due assessment of all technical, safety, and security considerations " would likely have been phrased rather differently if the lab in India were not considered capable of the work involved.

On edit:
And mods, apologies, this is getting rather more tangential to the incident than I intended!
First_Principal
June 28, 2025, 05:47:00 GMT
permalink
Post: 11912344
In keeping with PilotDAR's request, here is some possibly useful information regarding the type of Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) likely installed in the Air India B787 (using long names etc for those who may be unfamiliar with various acronyms).

The B787 was one of the first aircraft to receive a new type of FDR/CVR, known as an Enhanced Airborne Flight Recorder (EAFR). Some detail of the time may be found here:

https://www.flightglobal.com/boeing-.../67970.article
https://www.militaryaerospace.com/po...for-boeing-787

I don't believe it's absolutely confirmed yet but earlier posts (thank you V1... Ooops et al ) indicated that the unit in question may be a GE Aviation Model 3254F, the document here gives some good detail, along with another doc from Skybrary that has some relevant information.

And this one discusses more on the 'new' ARINC-767 protocol in use with these later units.

Some broader background into ARINC's role in determining the standards applicable to aviation can be seen in this video. While it doesn't specifically cover ARINC-767 (used by the B787 EAFR) the history and associated detail is interesting and may give a little useful background:




In terms of actual data recovery I had a look around but couldn't find any video that showed this from an EAFR, however this NTSB YT link gives insight into how data was recovered from an earlier FDR unit (mounted in a Bombardier CRJ700 ). While it's different to that installed in the 787 the nature of the work and how it's carefully carried out may give some insight.




Finally, this is a link to a short report re data recovered from an EAFR in a B787-9:

https://data.ntsb.gov/Docket/Documen...ort-Master.PDF

I claim no specific knowledge here, just providing references to detail I read while trying to learn more about these newer units.

FP.

za9ra22
June 29, 2025, 17:13:00 GMT
permalink
Post: 11913135
Originally Posted by EDLB
I find it very disconcerting that with downloaded recorders the investigators seem to have no clue how and why the dual engine shut down happened.
I don't see any direct confirmation that the flight recorder(s) have been read and their data determined, just that the AAIB have them in their custody, and they aren't going anywhere else.

To be honest, I don't see any detail in this reported conversation that tells me the Minister has any actual knowledge of the state of play in the investigation itself, just the process and a general round-up of what we basically already know.

My guess is that the investigation has not provided any feedback yet - or at least none that the Minister is able to pass on.
Lonewolf_50
June 30, 2025, 13:08:00 GMT
permalink
Post: 11913613
Originally Posted by The Brigadier
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.
Then why didn't that happen on the previous flight from Deli to Ahmedabad, or any of the previous flights since that engine install in March?
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.
Thanks for the update, and in particular that bolded bit.
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
artee
July 09, 2025, 07:04:00 GMT
permalink
Post: 11918167
Air India jet's fuel switches in focus, as crash preliminary report nears

From Reuters

Summary
  • Air India crash probe focuses on engine fuel control switches - source
  • Preliminary report expected by Friday - sources
  • Report could provide early details into world's worst aviation disaster in a decade
  • Probe has been dogged by questions over lack of information
  • India reversed course and now allowing UN specialist observer status - sources
July 8 (Reuters) - A preliminary report into the deadly crash of an Air India jetliner in June is expected to be released by Friday, three sources with knowledge of the matter said, with one adding the probe had narrowed its focus to the movement of the plane's fuel control switches.

The London-bound Boeing (BA.N) 787 Dreamliner, which started losing height after reaching an altitude of 650 feet, crashed moments after takeoff from Ahmedabad, India, killing 241 of the 242 people on board and the rest on the ground.

The investigation into the Air India crash is focusing on the movement of the engine fuel control switches following an analysis of the 787's flight and voice data recorders, along with a simulation by Boeing of the aircraft's final moments, one of the sources said.

The investigation has not raised any immediate concerns over mechanical failure, the source said, and there has been no bulletin to airlines recommending changes to 787 operations . Boeing declined to comment.

Aviation industry publication the Air Current first reported the focus on the fuel switches that help power the plane's two engines.

It was not clear what specific actions involving the fuel switches are being looked at by investigators. Sources told the Air Current that the available information on the black boxes could not rule in or out improper, inadvertent or intentional actions that preceded or followed the apparent loss of thrust before the aircraft crashed.

U.S. aviation safety expert John Cox said a pilot would not be able to accidentally move the fuel switches that feed the engines. "You can't bump them and they move," he said.

Cox added that if a switch was shut off, the effect would be almost immediate, cutting off engine power.

Most air crashes are caused by multiple factors. The investigation is focusing at least partly on engine thrust , Reuters reported last month.

While the report from Indian investigators could be made public on Friday, the three sources cautioned to Reuters that plans could change and there was no clarity on how much information would be available in the document, which comes about 30 days after the June 12 tragedy.

The sources spoke on condition of anonymity because they were not authorised to speak to media.

India's Aircraft Accident Investigation Bureau, which is leading the probe under international rules , did not respond immediately to a request for comment outside normal business hours.

INFORMATION RELEASE

The probe has been dogged by questions over lack of information, after investigators took about two weeks to download flight recorder data after the crash. The Indian government held only one press conference on the incident, and no questions were taken.

However, India reversed course on an earlier decision reported by Reuters to prevent a U.N. aviation investigator from joining the probe, two senior sources said.

A specialist from the U.N.'s International Civil Aviation Organization (ICAO) was granted observer status, following an unusual request by the agency to offer its support.

ICAO declined to comment, adding in a statement that any public discussion of "cooperative arrangements," would require authorisation by the state.

The crash is challenging the Tata Group's ambitious campaign to restore Air India's reputation and revamp its fleet, after taking the carrier over from the government in 2022.

India is banking on a boom in aviation to support wider development goals, with New Delhi saying it wants India to be a job-creating global aviation hub along the lines of Dubai, which currently handles much of the country's international traffic.

A panel of Indian lawmakers will review safety in the country's civil aviation sector and has invited several industry and government officials to answer questions on Wednesday, with topics set to include the recent plane crash.

Reporting by Allison Lampert in Montreal and David Shepardson in Washington; Additional reporting by Dan Catchpole in Seattle and Kanjyik Ghosh in Bengaluru; Editing by Jamie Freed

za9ra22
July 09, 2025, 14:17:00 GMT
permalink
Post: 11918422
Originally Posted by The Brigadier
Unfortunately, it's looking like poster's concerns about political interference, national pride in using a brand new lab in India to extract 'black box' content and the desire not to damage the reputation of a 'flag carrier' are well founded.
Nonsense.

There isn't anything of a factual nature to tell us that the investigation is suffering 'political interference', or that there is any issue in the use of the new lab to extract data from the flight recorders. There's unsubstantiated and improbable speculation in the guise of reporting that the data recorders might get sent elsewhere, but no credible sign this was ever planned.

Plus... 'flag carrier'? Air India is a wholly owned subsidiary of Tata, not an organ of state. And prior to it's purchase by them, the Indian government didn't seem overly concerned about the airline or its future. Hard to see why they would now.

The only thing well founded will be found in the accident report.
Magplug
July 09, 2025, 14:45:00 GMT
permalink
Post: 11918435
As a 787 operator I can observe a couple of things......

Deliberately cycling the Engine Cutoff switches just after rotate, in response to a dual power loss is inconceivable. You are way too low and slow for it to have any effect and your attention is better devoted to aiming for the flattest area ahead to crash into. Commencing the Dual Eng Fail/Stall checklist memory items is conditional upon both engines being at sub-idle and the aircraft being within the in-flight relight envelope. Neither of those conditions existed.

The flight recorder will witness what came first - Power loss or Start Switches to Cutoff? It seems the 'Third Contingency' that I alluded to about a thousand posts ago, sadly now seems likely. Given the iron-grip that the government appears to have over the media, one wonders how the truth will ever surface?
Musician
July 09, 2025, 15:09:00 GMT
permalink
Post: 11918452
Originally Posted by AirScotia
Do the switches make an audible clicking sound, ie one that would be picked up by the cockpit recorders?
If the switches were operated after the power went out, they didn't cause the accident.
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 .