June 22, 2025, 13:14:00 GMT
permalink Post: 11908532
That aside, I think we're agreed that downloading an intact FDR/EAFR is probably several orders of magnitude easier than one that's been burnt, battered or bruised.
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.
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.
June 22, 2025, 15:21:00 GMT
permalink Post: 11908618
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 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.
June 22, 2025, 16:17:00 GMT
permalink Post: 11908653
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.
June 22, 2025, 16:37:00 GMT
permalink Post: 11908670
In reverse order, and the first one being very speculative: The type of battery will likely be highly specific for the usecase, here rugged before anything else. Likely specialized chemistry or one of those hybrid solid state ones. Commonly they trade capacity for other features.
Regarding the recording feature, there's three types of microphone commonly used nowadays: Condenser and Ribbon type are somewhat fragile and require power to record audio while Dynamic type is basically a reverse speaker and is considered rugged. There's an off chance that a Piezzo microphone would be used here as they are basically indestructible but usually reserved for recording while in contact with a large sound transducer. My guess based on that is that we're looking at a dynamic microphone with a run of the mill preamp.
Depending on the actual electric setup this would yield a handful of different possible installations:
1) The "Cockpit Area Microphone" (hereby christened CAM because I like abbreviations) is a self contained unit consisting of a Microphone, a preamp and AD converter. This would mean while provided power the digital recording could be passed to either EAFR.
2) The CAM is a self contained unit consisting of a Microphone and a preamp. This would mean while provided power it could send an analog audio signal to the forward EAFR no problem, but would potentially struggle generating enough of a signal to be picked up by the rear EAFR.
3) The CAM is just a Microphone. This would mean it requires either no or very little power (even Condenser Mics usually require only Milliwatts) but the signal would be very hard to send over long distances and would require the EAFR to have a preamp.
In general it is audio engineering 101 to place a preamp as close to the source as possible to avoid noise. Thus I would rule out 3. It has both ups and downs to convert the analog signal to a digital signal, and there is a possibility they'd do both. In either case I am confused from an audio engineering standpoint why the rear EAFR would not pickup audio from the CAM if the forward EAFR does. Unless the rear EAFR is fed (audio) data only via BUS, which would be an interesting choice.
Also keep in mind that historically the CVR was also located in the tail section and very much received an analog signal over the entire distance. There's really no technical reason this wouldn't be possible, I routinely use far longer cables when running audio signals at concerts and those can't use compression because it would dumpster sound quality.
So, yeah, I don't understand why there would be a mismatch between the recordings of either EAFR, unless there was something else preventing all signal transmission towards the rear EAFR. The CVR in the rear has been a thing for 80 years now.
Regards,
Justus
Regarding the recording feature, there's three types of microphone commonly used nowadays: Condenser and Ribbon type are somewhat fragile and require power to record audio while Dynamic type is basically a reverse speaker and is considered rugged. There's an off chance that a Piezzo microphone would be used here as they are basically indestructible but usually reserved for recording while in contact with a large sound transducer. My guess based on that is that we're looking at a dynamic microphone with a run of the mill preamp.
Depending on the actual electric setup this would yield a handful of different possible installations:
1) The "Cockpit Area Microphone" (hereby christened CAM because I like abbreviations) is a self contained unit consisting of a Microphone, a preamp and AD converter. This would mean while provided power the digital recording could be passed to either EAFR.
2) The CAM is a self contained unit consisting of a Microphone and a preamp. This would mean while provided power it could send an analog audio signal to the forward EAFR no problem, but would potentially struggle generating enough of a signal to be picked up by the rear EAFR.
3) The CAM is just a Microphone. This would mean it requires either no or very little power (even Condenser Mics usually require only Milliwatts) but the signal would be very hard to send over long distances and would require the EAFR to have a preamp.
In general it is audio engineering 101 to place a preamp as close to the source as possible to avoid noise. Thus I would rule out 3. It has both ups and downs to convert the analog signal to a digital signal, and there is a possibility they'd do both. In either case I am confused from an audio engineering standpoint why the rear EAFR would not pickup audio from the CAM if the forward EAFR does. Unless the rear EAFR is fed (audio) data only via BUS, which would be an interesting choice.
Also keep in mind that historically the CVR was also located in the tail section and very much received an analog signal over the entire distance. There's really no technical reason this wouldn't be possible, I routinely use far longer cables when running audio signals at concerts and those can't use compression because it would dumpster sound quality.
So, yeah, I don't understand why there would be a mismatch between the recordings of either EAFR, unless there was something else preventing all signal transmission towards the rear EAFR. The CVR in the rear has been a thing for 80 years now.
Regards,
Justus
My understanding is that, as you say, the CAM has a preamp. That preamp can be powered by the RIPS that accompanies the forward EAFR.
In addition, I believe there is a single analogue connection from the CAM+preamp to the aft EAFR in addition to the analogue connection from the CAM+preamp to the forward EAFR. I believe, but am not sure,that the other flight-deck audio (headsets) is carried digitally over the fibre-optic network to the aft EAFR. The network may or may not be in operation in the event of an electrical failure: I simply don't know.
The publicly available information I can find is not stunningly clear about this.
AEROSAFETY WORLD, January 2008 - https://flightsafety.org/asw/jan08/a...47-48.pdf?dl=1
In the 787, the EAFRs store within their CVR-function memory partitions two hours of data from four audio channels and all data link messages. \x93The CVR function receives audio from three digital audio crew channels provided by the flight deck audio system and one analog audio channel from the cockpit area microphone and preamplifier,\x94 Elliott said.( Jim Elliott, a systems/applications engineer for the manufacturer. )
The Cockpit Voice Recorder function records the flight deck communications between crew members and also captures the general acoustical sound environment of the flight deck. The CVR function receives three analog audio crew channels provided by the Flight Deck Audio System and one analog audio channel from the cockpit Area Microphone and Preamplifier (AMP). The cockpit area audio and the three audio crew channels are recorded in both the forward and the aft installed EAFR recorders. The CVR recording duration is two hours minimum. Recorded audio can only be downloaded when the EAFR is off the aircraft.
https://data.ntsb.gov/Docket/Documen...ort-Master.PDF
Two EAFRs are installed on Boeing 787 aircraft, one forward and one aft. The forward and aft recorders are powered by the left and right 28V DC buses respectively. The forward recorder is equipped with a recorder independent power supply (RIPS) to provide backup power to the recorder for approximately 10 minutes once left DC bus power is lost. Both recorders record the same set of flight data independent of each other.
What I have been unable to determine is whether the right and/or left 28 V DC buses are powered from the main battery in case of failure of the AC power supply. To my untrained eye, it looks like the Captain's flight displays are powered from the main battery in extremis (28 V DC - C1), but that there are various circuit breakers, that could be automated, that may or may not allow or prevent other loads (such as the F/O's flight displays (28 V DC - C2), or the aft EAFR, being supplied by the main battery, (See link to diagram). There could well be very drastic automated load shedding.
https://kb.skyhightex.com/wp-content...l-1024x640.png
If the right 28 V DC bus was unpowered for any period, it follows that the aft EAFR was not recording for that period. This would make the forward EAFR important in case of a power failure that prevented the right 28 V DC bus from providing power.
All the information that is unclear to me will be transparently clear to the crash investigators. But it seems to me that the aft EAFR will not hold data for any period that the right 28 V DC bus is not operating. Whether that applies to this incident is an open question.
June 22, 2025, 17:50:00 GMT
permalink Post: 11908714
SLF here. Mods - please delete summarily if this does not contribute to the discussion, I have no wish to waste anyones time. No 'AI' was used in the preparation of this post.
My understanding is that, as you say, the CAM has a preamp. That preamp can be powered by the RIPS that accompanies the forward EAFR.
In addition, I believe there is a single analogue connection from the CAM+preamp to the aft EAFR in addition to the analogue connection from the CAM+preamp to the forward EAFR. I believe, but am not sure,that the other flight-deck audio (headsets) is carried digitally over the fibre-optic network to the aft EAFR. The network may or may not be in operation in the event of an electrical failure: I simply don't know.
The publicly available information I can find is not stunningly clear about this.
AEROSAFETY WORLD, January 2008 - https://flightsafety.org/asw/jan08/a...47-48.pdf?dl=1
GE Aviation: Consolidate and increase recording power with the 3254F EAFR. - https://www.geaerospace.com/sites/de...rder-3254F.pdf
As for power, this NTSB document describes the power set-up for the EAFRs
https://data.ntsb.gov/Docket/Documen...ort-Master.PDF
So the forward EAFR is powered from the left 28V DC bus with the possibility of being powered by the RIPS, and the aft EAFR is powered from the right 28 V DC bus.
What I have been unable to determine is whether the right and/or left 28 V DC buses are powered from the main battery in case of failure of the AC power supply. To my untrained eye, it looks like the Captain's flight displays are powered from the main battery in extremis (28 V DC - C1), but that there are various circuit breakers, that could be automated, that may or may not allow or prevent other loads (such as the F/O's flight displays (28 V DC - C2), or the aft EAFR, being supplied by the main battery, (See link to diagram). There could well be very drastic automated load shedding.
https://kb.skyhightex.com/wp-content...l-1024x640.png
If the right 28 V DC bus was unpowered for any period, it follows that the aft EAFR was not recording for that period. This would make the forward EAFR important in case of a power failure that prevented the right 28 V DC bus from providing power.
All the information that is unclear to me will be transparently clear to the crash investigators. But it seems to me that the aft EAFR will not hold data for any period that the right 28 V DC bus is not operating. Whether that applies to this incident is an open question.
My understanding is that, as you say, the CAM has a preamp. That preamp can be powered by the RIPS that accompanies the forward EAFR.
In addition, I believe there is a single analogue connection from the CAM+preamp to the aft EAFR in addition to the analogue connection from the CAM+preamp to the forward EAFR. I believe, but am not sure,that the other flight-deck audio (headsets) is carried digitally over the fibre-optic network to the aft EAFR. The network may or may not be in operation in the event of an electrical failure: I simply don't know.
The publicly available information I can find is not stunningly clear about this.
AEROSAFETY WORLD, January 2008 - https://flightsafety.org/asw/jan08/a...47-48.pdf?dl=1
GE Aviation: Consolidate and increase recording power with the 3254F EAFR. - https://www.geaerospace.com/sites/de...rder-3254F.pdf
As for power, this NTSB document describes the power set-up for the EAFRs
https://data.ntsb.gov/Docket/Documen...ort-Master.PDF
So the forward EAFR is powered from the left 28V DC bus with the possibility of being powered by the RIPS, and the aft EAFR is powered from the right 28 V DC bus.
What I have been unable to determine is whether the right and/or left 28 V DC buses are powered from the main battery in case of failure of the AC power supply. To my untrained eye, it looks like the Captain's flight displays are powered from the main battery in extremis (28 V DC - C1), but that there are various circuit breakers, that could be automated, that may or may not allow or prevent other loads (such as the F/O's flight displays (28 V DC - C2), or the aft EAFR, being supplied by the main battery, (See link to diagram). There could well be very drastic automated load shedding.
https://kb.skyhightex.com/wp-content...l-1024x640.png
If the right 28 V DC bus was unpowered for any period, it follows that the aft EAFR was not recording for that period. This would make the forward EAFR important in case of a power failure that prevented the right 28 V DC bus from providing power.
All the information that is unclear to me will be transparently clear to the crash investigators. But it seems to me that the aft EAFR will not hold data for any period that the right 28 V DC bus is not operating. Whether that applies to this incident is an open question.
Having two combined recorders is already more backup than what had previously been the norm, in addition theres the independently powered area mic going analog to the front recorder.
The common models I have checked the sheets for also provides a digital output (which is probably sent to the aft recorder via normal busses.
Having a seperate analog line going to the aft recorder would be several Kg of extra weight, and probably a substantial amount of loom design and paperwork for what is then a backup to an already redundant system.
Hence, imho why this signal only goes to the forward recorder. It is already a \xabbonus\xbb.
The power for microphone and preamp is in the >1watt range range, completely insignificant.
I am still interested in reliable information as to what is expected to be on the recorder of an aircraft which has lost the generators, what about the battery powered prinary instruments? Does some systems and the aft recorder come online with the RAT or would everything be down to the one cockpit mic? Surely not?
June 22, 2025, 18:03:00 GMT
permalink Post: 11908723
But even then, if I may borrow part of previous quote:
Those are two drastically different things :
* I believe blindly that the " foremost global centres of IT hardware " can recover each and every bit on my drowned IPhone and would not hesitate for a second to handover my phone
* However, I would not trust and/or handover my damaged EAFR to any of those " centres of IT hardware", even just to look at it, let alone touch it, until it was proven that the centre in question, has all the approvals, certifications, qualifications, track record and whatever. So, moon landings or not, that does not prove anything.
June 22, 2025, 18:13:00 GMT
permalink Post: 11908726
No, no, I was thinking about the FDR data being downloadable from the EAFR through the aircraft's network. Be it with the Maintenance Laptop (which I presume) or any kitchen-grade laptop with a physical ethernet port (which I hope is not the case). But I have no clue on what an appropriate device is for such an operation.
Regarding the QAR, the 787 is or can be equipped with a WQAR, but I hate to type the W, as in Wireless, as the moment I hit the 'enter' button, Starlink interfaces will be devised and engineered on the spot....
Regarding the QAR, the 787 is or can be equipped with a WQAR, but I hate to type the W, as in Wireless, as the moment I hit the 'enter' button, Starlink interfaces will be devised and engineered on the spot....
June 22, 2025, 18:17:00 GMT
permalink Post: 11908731
Err, it is not your EAFR. It belongs to an Indian company and is under the jurisdiction of India. But it is natural to believe that your country can do a better job than any foreigners.
June 22, 2025, 21:47:00 GMT
permalink Post: 11908831
No, no, I was thinking about the FDR data being downloadable from the EAFR through the aircraft's network. Be it with the Maintenance Laptop (which I presume) or any kitchen-grade laptop with a physical ethernet port (which I hope is not the case). But I have no clue on what an appropriate device is for such an operation.
Regarding the QAR, the 787 is or can be equipped with a WQAR, but I hate to type the W, as in Wireless, as the moment I hit the 'enter' button, Starlink interfaces will be devised and engineered on the spot....
Regarding the QAR, the 787 is or can be equipped with a WQAR, but I hate to type the W, as in Wireless, as the moment I hit the 'enter' button, Starlink interfaces will be devised and engineered on the spot....
June 26, 2025, 16:01:00 GMT
permalink Post: 11911339
https://www.pib.gov.in/PressReleseDe...x?PRID=2139785
Status Report on recovery and examination of data from Black Boxes – Air India Flight AI-171
Note the front EAFR is the one with RIPS battery backup.
Status Report on recovery and examination of data from Black Boxes – Air India Flight AI-171
On the evening of 24 June 2025, the team led by DG AAIB with technical members from AAIB and NTSB began the data extraction process. The Crash Protection Module (CPM) from the front black box was safely retrieved, and on 25 June, 2025, the memory module was successfully accessed and its data downloaded at the AAIB Lab.The analysis of CVR and FDR data is underway. These efforts aim to reconstruct the sequence of events leading to the accident and identify contributing factors to enhance aviation safety and prevent future occurrences.
June 26, 2025, 21:39:00 GMT
permalink Post: 11911519
https://www.pib.gov.in/PressReleseDe...x?PRID=2139785
Status Report on recovery and examination of data from Black Boxes \x96 Air India Flight AI-171
Note the front EAFR is the one with RIPS battery backup.
Status Report on recovery and examination of data from Black Boxes \x96 Air India Flight AI-171
Note the front EAFR is the one with RIPS battery backup.
1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss;
2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake.
Regards,
D Bru
June 26, 2025, 21:58:00 GMT
permalink Post: 11911531
Thx, this indicates at least two issues:
1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss;
2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake.
Regards,
D Bru
1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss;
2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake.
Regards,
D Bru
June 26, 2025, 22:05:00 GMT
permalink Post: 11911534
Really, Grumpy? If aft EAFR (not RIPS supported) would have had any data/voice after elec failure following T/O, I think the AAIB would have been more than happy to extract everything from that one since it was found earlier and most likely more intact than the front one. Regards
Last edited by D Bru; 26th June 2025 at 22:17 . Reason: Sorry but I didn't want to sound too "grumpy" ;)
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.
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.
June 28, 2025, 07:27:00 GMT
permalink Post: 11912371
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..
June 28, 2025, 13:13:00 GMT
permalink Post: 11912486
I suspect both recorders will contain the same data. Given the radio transmission after the loss of thrust the aircraft still had at least the emergency electrical bus powered. This should have kept both recorders online. It is however possible given the 10 minute battery backup that Boeing chose to put the the recorders on another bus but that\x92s not the norm.
CVR and FDR, och combined such is not needed for survival.
I would state that in general the CVR/FDR is shedded when on emergency electricity.
Its clear from earlier posts that the front EAFR have a battery backup for this reason and the aft has not.
June 28, 2025, 13:42:00 GMT
permalink Post: 11912496
Making a guess that the BBU EAFR being in the front is that it's closer to a lot of the data sources and less likely to lose data if there's damage to the long cable runs to the boot (?)
June 28, 2025, 15:54:00 GMT
permalink Post: 11912544
It's not clear to me that 787 EAFR even requires an external DFDAU. The GE EAFR does not -
"Provides Flight Data Acquisition function of ARINC 664 p7 data parameters – No need for a Digital Flight Data Acquisition Unit (DFDAU)."
ref https://www.geaerospace.com/sites/de...rder-3254F.pdf