DFDR Page: 5 of 5

sabenaboy
July 17, 2025, 09:36:00 GMT
permalink Post: 11924222

Quote:

Originally Posted by barrymung

You forget, circumstances are different.

It has taken a while to get the "golden" flight recorder shipped, for instance, to recover the data.

I could understand that it took more then 48 hrs. But a month? And then still be vague about it?

Subjects DFDR

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JustusW
August 01, 2025, 20:02:00 GMT
permalink Post: 11932029

The only new information I could find is this: https://www.msn.com/en-in/news/India...be/ar-AA1JFQJo

Quote:

The Aircraft Accident Investigation Bureau has roped in human factors specialists to assist with its ongoing investigation into the AI-171 Ahmedabad crash, the government told Parliament on Thursday.“B787 type-rated experienced pilots, type-rated engineers, aviation medicine specialists, human factor specialists, and flight recorder specialists have been taken on board as subject matter experts to assist the investigation," Minister of State for Civil Aviation Murlidhar Mohol said.

This move follows multiple reports in Western media blaming the senior pilot for the fatal crash.

Subjects AI171 DFDR Human Factors

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Someone Somewhere
November 28, 2025, 20:11:00 GMT
permalink Post: 11997382

Quote:

Originally Posted by Musician

original source: https://thefederal.com/category/busi...failure-217674

Quote:

The Emergency Locator Transmitter (ELT), a critical post-crash distress beacon, was never activated, as per the AAIB report. It was recovered intact in the wreckage, yet it was silent.A CCS/core network failure would not by itself stop the transmission from an ELT’s automatic g-switch — which is a gravity (g) switch with a sensor that detects sudden changes in acceleration (g-forces) that typically occur during a crash.

That is, unless the ELT’s antenna and wiring had melted in a fire — and one possible pointer to that is a Category A fault logged on AI 171’s Nitrogen Generation System (NGS), a safety feature Boeing added to prevent fuel tank fires in the aftermath of the Trans World Airlines Flight 800’s midair explosion due to a central fuel tank ignition in 1996.

The NGS works by continuously flooding the tail fuel tank’s ullage (the empty space above the fuel) with nitrogen-rich air, displacing oxygen and thereby preventing the build-up of flammable vapours.

If the NGS were not functioning, the oxygen levels around the aft-fuel tank bay may have been dangerously high. In that scenario, even a small spark—possibly from an electric arc or surge—could ignite a localised fuel-air vapour fire. That would have burnt the wiring and antenna of the ELT and wiring, connectors, and housing of tail-section black box or the aft Enhanced Airborne Flight Recorder (EAFR). And this scenario would be in line with the AAIB report, which shows the tail section was more structurally intact compared to the nose.

We're back to this rubbish.

There's a good 20m of cabin between the centre fuel tanks (there is no 'aft fuel tank bay' on a 787) and the ELT/aft EAFR which are IIRC more-or-less above the rear doors.

The rest isn't much better.

I also see no mention of the fact that virtually everything in the CCS/CDN/CCRs is at least duplicated.

Last edited by Senior Pilot; 29th November 2025 at 03:07 . Reason: Add source of the quote

Subjects AAIB (All) DFDR EAFR

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EDML
December 23, 2025, 22:30:00 GMT
permalink Post: 12010160

Quote:

Originally Posted by VicMel

This led me to think - could the Air India 171 crash be due to solar radiation?

Like all theories that have been around so far it does not explain crucial parts of the accidents.
Most important: Why did the DFDR record a fuel shutoff commanded by the switches on the flight deck.

Furthermore: There is more than one source for the Air/Ground logic for the TCMA. There are two engines with two FADECs each. A bit flip, which might be very remotely possible, is not enough to trigger that sequence of events. Furthermore they were more or less on the ground - the A320 affected by solar flare was at FL350 which makes a huge difference.

Last edited by T28B; 23rd December 2025 at 22:49 . Reason: removed the so called 'theory' and bolded the salient point...

Subjects DFDR

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Musician
December 24, 2025, 11:27:00 GMT
permalink Post: 12010358

Quote:

Originally Posted by Den2020

Hi @ all,
does someone has more information about the so-called 'Golden Chassis'? Does only Boeing has it or are there several of them, which are not owned by Boeing, worldwide available? How does this Chassis work and can the readout be counter-checked? And is it possible to manipulate them?
Regards

Boeing is not involved.

https://www.taxtmi.com/news?id=49252

Generally, data from damaged flight recorders is downloaded after sourcing Golden Chassis and relevant download cables from other accident investigation authorities.

In the current investigation, AAIB on Saturday said the Golden Chassis or the identical EAFR unit and download cables required to download data from EAFR were sourced from the US National Transport Safety Board (NTSB).

https://www.flightradar24.com/blog/a...-an-air-crash/

The crash-survivable memory unit (CSMU) is the most critical component, as it stores the valuable flight data. If necessary, specialists transfer data chips into a golden chassis, a specialized device that prevents further data loss while allowing a safe download. “We have in the laboratory every western-made flight recorder, ordered from the manufacturers with one simple modification: a modification that turns off any further writing of data,” Payne explained.

https://safetycompass.wordpress.com/...-recorder-lab/
[img alt="A shelf unit housing nearly every known type of flight data recorder.
These surrogate recorders are known as 'Golden Chassis'."]https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1280x2000/recorders_copy_d214c286ab80e3503be1845ff4dd875d18f362b1.jpg[/img]

A shelf unit housing nearly every known type of flight data recorder. These surrogate recorders are known as “Golden Chassis”.

I believe the French BEA have a similarly well-stocked store of flight recorders. Other agencies might, as well.

Subjects AAIB (All) DFDR EAFR

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VicMel
December 24, 2025, 12:22:00 GMT
permalink Post: 12010375

Only 1 Failure

Quote:

Originally Posted by EDML

The Landing Gear System I am familiar with determined and set WoW status, as well as computing aircraft weight from a load cell situated on the LG structure. Only one system, only one bit for WoW status, just one failure; then the TCMA does the rest. I read somewhere that the Pilots tried to do an engines restart by recycling the fuel cutoff switches, so I have no idea where the switches might have ended up - but TCMA does not care!

Last edited by VicMel; 24th December 2025 at 12:25 . Reason: missed out "with"

Subjects DFDR Fuel (All) Fuel Cutoff Fuel Cutoff Switches Relight

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Someone Somewhere
January 23, 2026, 08:10:00 GMT
permalink Post: 12025591

I would be embarrassed to submit a document of that quality internally, let alone to Government.

The shown images look like overheating at terminals and that tends to be the cause of electrical fires. Could certainly be workmanship or design/underspecification issues and a concern.

There isn't the slightest chance that either could cause failure of self-powered engines during the takeoff roll, let alone cause the flight recorders to record not just no data, but credible false data.

It's like saying your car crashed into a bridge support at 220km/h because of a recurring slow leak in one tire.

Subjects DFDR Takeoff Roll

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Someone Somewhere
January 24, 2026, 20:21:00 GMT
permalink Post: 12026564

Quote:

Originally Posted by Musician

Non-paywalled version: https://www.aol.com/articles/sabotag...060100148.html
There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:

"The aft EAFR burned before the crash" was I believe originally an attempt to tie it to the aft battery fires the 787 had more than a decade ago, as they're both 'aft'. Never mind that the aft electronics bay (APU battery) is under the floor near the wheel well while the aft EAFR is above the ceiling near the rear doors.

Quote:

Originally Posted by Ver5pen

whilst intentional action is the most obvious explanation one can’t ignore data and technical grounds if one is also going to dismiss counter theories on technical grounds

I still don’t believe we have got a clear answer on the recording interval of the engine cutoff switch channel, if it’s 1s then the ‘debunking’ by saying it can be done very quickly is moot as (near) instant would record as 1s I believe

It's one second intervals but not necessarily recorded simultaneously. The NTSB has a few FDR reports from previous 787s that should show roughly what you would expect. I don't see any discrepancy.

Quote:

and the RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs were recorded as moved is obviously hugely consequential

RAT out would be recorded on the EAFR I believe, they just haven't explicitly specified when it happened.

The engines ran down after the switches were recorded moving. Even if the RAT deployed, that does not suggest that the crew switched the engines off because of an engine failure.

No crew is going to shut down the engines down simply because a RAT deploys unexpectedly.

Quote:

it’s easy to dismiss these narratives as vested interests but let’s be honest everyone has a vested interest here and blaming the pilots has been the go to when in doubt for a very very long time- probably as long as aviation has existed

in the absence of explicit evidence (does the CVR have more to tell?) of deliberate action or pre-planning this is a horrifically complicated investigation as there will always be plausible deniability on all sides and different courts/judges will rule on it very differently based on their own biases and views

It is very, very, very hard to argue that the EAFR records valid data for A/B/C/D but generates fake data for X/Y/Z, but the fake data is still externally and internally consistent. Which seems to be where we are now.

I don't think you can or will effectively prove whether it was intentional or some kind of an action slip, and by which pilot.

I think the accident report will be able to very clearly and with no reasonable doubt show that the switches were physically moved.

From the article:

Quote:

The alternative is too awful for them to contemplate : that one of the pilots murdered hundreds of people as collateral damage in a suicide.

And there you have the answer. If you refuse to consider the scary option, whatever remains must be the 'truth'.

Quote:

Because the aft flight recorder was destroyed, investigators cannot retrieve the one piece of information that it alone contained – the moment it stopped working, which might have provided a vital clue about a fire or electrical failure in the moments before the crash.

Have we had actual confirmation that the aft EAFR was completely unrecoverable? I don't believe so; the preliminary report said this:

Quote:

The aft EAFR was substantially damaged and could not be downloaded through conventional means. The CPM was opened to inspect the memory card. The damage was extensive.

The forward EAFR will have shown when each bus lost power and if they don't believe there's any unique data on the aft EAFR, attempting to recover data from it is basically an academic exercise.

Last edited by Someone Somewhere; 24th January 2026 at 20:32 .

Subjects APU Action slip CVR DFDR EAFR Electrical Failure Engine Failure (All) FDR Fuel (All) Fuel Cutoff Switches NTSB Preliminary Report RAT (All) RAT (Deployment)

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sabenaboy July 17, 2025, 09:36:00 GMT permalink Post: 11924222	Quote: Originally Posted by barrymung You forget, circumstances are different. It has taken a while to get the "golden" flight recorder shipped, for instance, to recover the data. I could understand that it took more then 48 hrs. But a month? And then still be vague about it? Subjects DFDR Links are to this post in the relevant subject page so that this post can be seen in context. 2 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
JustusW August 01, 2025, 20:02:00 GMT permalink Post: 11932029	The only new information I could find is this: https://www.msn.com/en-in/news/India...be/ar-AA1JFQJo Quote: The Aircraft Accident Investigation Bureau has roped in human factors specialists to assist with its ongoing investigation into the AI-171 Ahmedabad crash, the government told Parliament on Thursday.“B787 type-rated experienced pilots, type-rated engineers, aviation medicine specialists, human factor specialists, and flight recorder specialists have been taken on board as subject matter experts to assist the investigation," Minister of State for Civil Aviation Murlidhar Mohol said. This move follows multiple reports in Western media blaming the senior pilot for the fatal crash. Subjects AI171 DFDR Human Factors Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
Someone Somewhere November 28, 2025, 20:11:00 GMT permalink Post: 11997382	Quote: Originally Posted by Musician original source: https://thefederal.com/category/busi...failure-217674 Quote: The Emergency Locator Transmitter (ELT), a critical post-crash distress beacon, was never activated, as per the AAIB report. It was recovered intact in the wreckage, yet it was silent.A CCS/core network failure would not by itself stop the transmission from an ELT’s automatic g-switch — which is a gravity (g) switch with a sensor that detects sudden changes in acceleration (g-forces) that typically occur during a crash. That is, unless the ELT’s antenna and wiring had melted in a fire — and one possible pointer to that is a Category A fault logged on AI 171’s Nitrogen Generation System (NGS), a safety feature Boeing added to prevent fuel tank fires in the aftermath of the Trans World Airlines Flight 800’s midair explosion due to a central fuel tank ignition in 1996. The NGS works by continuously flooding the tail fuel tank’s ullage (the empty space above the fuel) with nitrogen-rich air, displacing oxygen and thereby preventing the build-up of flammable vapours. If the NGS were not functioning, the oxygen levels around the aft-fuel tank bay may have been dangerously high. In that scenario, even a small spark—possibly from an electric arc or surge—could ignite a localised fuel-air vapour fire. That would have burnt the wiring and antenna of the ELT and wiring, connectors, and housing of tail-section black box or the aft Enhanced Airborne Flight Recorder (EAFR). And this scenario would be in line with the AAIB report, which shows the tail section was more structurally intact compared to the nose. We're back to this rubbish. There's a good 20m of cabin between the centre fuel tanks (there is no 'aft fuel tank bay' on a 787) and the ELT/aft EAFR which are IIRC more-or-less above the rear doors. The rest isn't much better. I also see no mention of the fact that virtually everything in the CCS/CDN/CCRs is at least duplicated. Last edited by Senior Pilot; 29th November 2025 at 03:07 . Reason: Add source of the quote Subjects AAIB (All) DFDR EAFR Links are to this post in the relevant subject page so that this post can be seen in context. 4 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
EDML December 23, 2025, 22:30:00 GMT permalink Post: 12010160	Quote: Originally Posted by VicMel This led me to think - could the Air India 171 crash be due to solar radiation? Like all theories that have been around so far it does not explain crucial parts of the accidents. Most important: Why did the DFDR record a fuel shutoff commanded by the switches on the flight deck. Furthermore: There is more than one source for the Air/Ground logic for the TCMA. There are two engines with two FADECs each. A bit flip, which might be very remotely possible, is not enough to trigger that sequence of events. Furthermore they were more or less on the ground - the A320 affected by solar flare was at FL350 which makes a huge difference. Last edited by T28B; 23rd December 2025 at 22:49 . Reason: removed the so called 'theory' and bolded the salient point... Subjects DFDR Links are to this post in the relevant subject page so that this post can be seen in context. 5 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
Musician December 24, 2025, 11:27:00 GMT permalink Post: 12010358	Quote: Originally Posted by Den2020 Hi @ all, does someone has more information about the so-called 'Golden Chassis'? Does only Boeing has it or are there several of them, which are not owned by Boeing, worldwide available? How does this Chassis work and can the readout be counter-checked? And is it possible to manipulate them? Regards Boeing is not involved. https://www.taxtmi.com/news?id=49252 Generally, data from damaged flight recorders is downloaded after sourcing Golden Chassis and relevant download cables from other accident investigation authorities. In the current investigation, AAIB on Saturday said the Golden Chassis or the identical EAFR unit and download cables required to download data from EAFR were sourced from the US National Transport Safety Board (NTSB). https://www.flightradar24.com/blog/a...-an-air-crash/ The crash-survivable memory unit (CSMU) is the most critical component, as it stores the valuable flight data. If necessary, specialists transfer data chips into a golden chassis, a specialized device that prevents further data loss while allowing a safe download. “We have in the laboratory every western-made flight recorder, ordered from the manufacturers with one simple modification: a modification that turns off any further writing of data,” Payne explained. https://safetycompass.wordpress.com/...-recorder-lab/ [img alt="A shelf unit housing nearly every known type of flight data recorder. These surrogate recorders are known as 'Golden Chassis'."]https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1280x2000/recorders_copy_d214c286ab80e3503be1845ff4dd875d18f362b1.jpg[/img] A shelf unit housing nearly every known type of flight data recorder. These surrogate recorders are known as “Golden Chassis”. I believe the French BEA have a similarly well-stocked store of flight recorders. Other agencies might, as well. Subjects AAIB (All) DFDR EAFR Links are to this post in the relevant subject page so that this post can be seen in context. 2 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
VicMel December 24, 2025, 12:22:00 GMT permalink Post: 12010375	Only 1 Failure Quote: Originally Posted by EDML Like all theories that have been around so far it does not explain crucial parts of the accidents. Most important: Why did the DFDR record a fuel shutoff commanded by the switches on the flight deck. Furthermore: There is more than one source for the Air/Ground logic for the TCMA. There are two engines with two FADECs each. A bit flip, which might be very remotely possible, is not enough to trigger that sequence of events. Furthermore they were more or less on the ground - the A320 affected by solar flare was at FL350 which makes a huge difference. The Landing Gear System I am familiar with determined and set WoW status, as well as computing aircraft weight from a load cell situated on the LG structure. Only one system, only one bit for WoW status, just one failure; then the TCMA does the rest. I read somewhere that the Pilots tried to do an engines restart by recycling the fuel cutoff switches, so I have no idea where the switches might have ended up - but TCMA does not care! Last edited by VicMel; 24th December 2025 at 12:25 . Reason: missed out "with" Subjects DFDR Fuel (All) Fuel Cutoff Fuel Cutoff Switches Relight Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
Someone Somewhere January 23, 2026, 08:10:00 GMT permalink Post: 12025591	I would be embarrassed to submit a document of that quality internally, let alone to Government. The shown images look like overheating at terminals and that tends to be the cause of electrical fires. Could certainly be workmanship or design/underspecification issues and a concern. There isn't the slightest chance that either could cause failure of self-powered engines during the takeoff roll, let alone cause the flight recorders to record not just no data, but credible false data. It's like saying your car crashed into a bridge support at 220km/h because of a recurring slow leak in one tire. Subjects DFDR Takeoff Roll Links are to this post in the relevant subject page so that this post can be seen in context. 3 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
Someone Somewhere January 24, 2026, 20:21:00 GMT permalink Post: 12026564	Quote: Originally Posted by Musician Non-paywalled version: https://www.aol.com/articles/sabotag...060100148.html There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all: "The aft EAFR burned before the crash" was I believe originally an attempt to tie it to the aft battery fires the 787 had more than a decade ago, as they're both 'aft'. Never mind that the aft electronics bay (APU battery) is under the floor near the wheel well while the aft EAFR is above the ceiling near the rear doors. Quote: Originally Posted by Ver5pen whilst intentional action is the most obvious explanation one can’t ignore data and technical grounds if one is also going to dismiss counter theories on technical grounds I still don’t believe we have got a clear answer on the recording interval of the engine cutoff switch channel, if it’s 1s then the ‘debunking’ by saying it can be done very quickly is moot as (near) instant would record as 1s I believe It's one second intervals but not necessarily recorded simultaneously. The NTSB has a few FDR reports from previous 787s that should show roughly what you would expect. I don't see any discrepancy. Quote: and the RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs were recorded as moved is obviously hugely consequential RAT out would be recorded on the EAFR I believe, they just haven't explicitly specified when it happened. The engines ran down after the switches were recorded moving. Even if the RAT deployed, that does not suggest that the crew switched the engines off because of an engine failure. No crew is going to shut down the engines down simply because a RAT deploys unexpectedly. Quote: it’s easy to dismiss these narratives as vested interests but let’s be honest everyone has a vested interest here and blaming the pilots has been the go to when in doubt for a very very long time- probably as long as aviation has existed in the absence of explicit evidence (does the CVR have more to tell?) of deliberate action or pre-planning this is a horrifically complicated investigation as there will always be plausible deniability on all sides and different courts/judges will rule on it very differently based on their own biases and views It is very, very, very hard to argue that the EAFR records valid data for A/B/C/D but generates fake data for X/Y/Z, but the fake data is still externally and internally consistent. Which seems to be where we are now. I don't think you can or will effectively prove whether it was intentional or some kind of an action slip, and by which pilot. I think the accident report will be able to very clearly and with no reasonable doubt show that the switches were physically moved. From the article: Quote: The alternative is too awful for them to contemplate : that one of the pilots murdered hundreds of people as collateral damage in a suicide. And there you have the answer. If you refuse to consider the scary option, whatever remains must be the 'truth'. Quote: Because the aft flight recorder was destroyed, investigators cannot retrieve the one piece of information that it alone contained – the moment it stopped working, which might have provided a vital clue about a fire or electrical failure in the moments before the crash. Have we had actual confirmation that the aft EAFR was completely unrecoverable? I don't believe so; the preliminary report said this: Quote: The aft EAFR was substantially damaged and could not be downloaded through conventional means. The CPM was opened to inspect the memory card. The damage was extensive. The forward EAFR will have shown when each bus lost power and if they don't believe there's any unique data on the aft EAFR, attempting to recover data from it is basically an academic exercise. Last edited by Someone Somewhere; 24th January 2026 at 20:32 . Subjects APU Action slip CVR DFDR EAFR Electrical Failure Engine Failure (All) FDR Fuel (All) Fuel Cutoff Switches NTSB Preliminary Report RAT (All) RAT (Deployment) Links are to this post in the relevant subject page so that this post can be seen in context. 3 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

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