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First_Principal
2025-06-12T22:07:00 permalink Post: 11899780 |
... Specifically, I live in Lynnwood, Washington directly under the approach path for Paine Field's runway 34 Left, and I've been there since 2007. I lived in Mukilteo from 2000-2007, which is more next to the runway than under it... Boeing manufactures the 777 and 787 at Paine field....The RAT is deployed and tested during EVERY SINGLE first flight of every aircraft Boeing produces that has a RAT installed. And sometimes it requires a re-test on subsequent flights.
So yeah, I have heard a deployed RAT, from the ground, HUNDREDS of times. I've heard it while preflighting my airplane, I've heard it while mowing my lawn, I've heard while lying in bed. And this is exactly what they always sounds like.... NOT especially getting at you slacktide , indeed thanks for the followup and presenting your experience/reasoning, however, to assist everyone, including *relevant* background/support detail with one's post is to be encouraged! If you don't have this, or are just speculating from a position of little experience or knowledge, maybe the best contribution would be to sit on your hands for a bit and learn from others? FP. Subjects: RAT (All) RAT (Deployment) 9 users liked this post. |
First_Principal
2025-06-14T09:19:00 permalink Post: 11901297 |
There has been much discussion here about RAT deployment. Various claims either way have been made, based on individual perspectives of available video and audio.
I am very mindful of just how awful a tragedy this is, and have significant misgivings about disproportionate interest in others misfortune where it carries no purpose, but also recognise that for some people knowing and learning what happened ASAP could be very important, particularly given the present circumstances. Thus while I sincerely hope that early detail from investigators will give some clarity, in an effort to reduce needless speculation regarding RAT deployment I have taken: (1) an audio sample from the video of AI171 passing by in which people claim to hear a RAT (2) an audio sample from a 787 video with RAT deployed on test by Boeing (3) an audio sample from a JAL 787 video with RAT deployed And passed these through a FFT in order to gain a more quantitative view of the noise spectra from each event. A spectrogram of the results is presented below. I hesitate to make any conclusions per se, but observe that there are similarities as well as divergences between them. In all three samples there is a relatively consistent signal roughly centered in the range 113-146Hz that could be what gives the characteristic 'buzz' sound of (apparently) a RAT in operation. JAL ~141Hz Test ~146Hz AI171 ~113-134Hz (prob doppler variation here) ![]() Spectral comparison AI171, B787 with RAT, JAL 787 with RAT ![]() Spectral comparison #2 AI171, B787 with RAT, JAL 787 with RAT These frequencies seem consistent(ish) with what I got from this video [[url]https://www.youtube.com/watch?v=O1r3CuRwjPc] in which a 787 RAT is being tested - albeit in this case the blades are hydraulically powered and not driven as a turbine. This test showed a fundamental frequency of 135Hz with relevant harmonics above (the second harmonic at 270Hz is higher SPL, no weighting): ![]() It's important to note that the initial recordings are necessarily different; these are not controlled conditions, the recording equipment is probably quite diverse and almost certainly not ideal, and the environmental conditions will also be different. Moreover all of these audio samples have come from video files referenced here, one has no way of determining the provenance or veracity of these sources and, crucially, I have no prior experience of analysing/extracting RAT acoustic fingerprints (nor have I sampled 'control' audio of a 787 passing by /without/ RAT!). Additionally it's been quite a long time since I did any work with [turbine] noise so given these and other variables I'm not prepared to make any declarations per se, but perhaps more knowledgeable people could. That said, my feeling from what I see is that RAT deployment is not dis proven, and that the apparent fundamental frequency difference between the samples may be explainable by - amongst other things - difference in a/c airspeed, bearing in mind that AI171 was on TO, the others were landing. Ultimately what I've done here is extremely rudimentary and while it would be possible to go into much more depth I'd hope that more definitive answer would be forthcoming by then, however if anyone wants to discuss specific methodology etc off-line please PM, no wish to add to noise on this thread. FP. Subjects: AI171 Audio Analysis RAT (All) RAT (Deployment) 18 users liked this post. |
First_Principal
2025-06-15T00:01:00 permalink Post: 11901977 |
Further on RAT deployment noise and acoustic analyses
Just commenting on the earlier acoustic analyses of RAT deployment conducted by
Kraftstoffvondesibel
and myself.
Firstly it will be clear that we posted our respective audio analyses about the same time. There was no collaboration I assure you, and in fact I'd been waiting all day to see if someone else with more recent or pertinent experience than me would do something. When I hadn't seen anything I spent a little time and came up with what I did, however I think Kraftstoffvondesibel's work is probably more useful than mine given their specific plot methodology and that they included a non-RAT 'control' pass. I was in the process of acknowledging this when the thread was closed; late at night for me which is why this post is now some hours on. At the time I posted I was fairly circumspect for the reasons given but, with the similarities between our results and along with some other detail that's come to light in PM, I am now more persuaded that the acoustic print we both observed is most likely to be from a RAT (although until this is confirmed a question must necessarily remain). FWIW, and in part answer to a later post enquiring about the noise of a RAT dropping into position, this also aligns somewhat with the survivor's apparent observation of a noise ('bang'?) prior to impact, and an earlier post by DaveReidUK stating that RAT deployment results in a 'humungous' bang. FP. Subjects: RAT (All) RAT (Deployment) Thread Closure 25 users liked this post. |
First_Principal
2025-06-15T02:23:00 permalink Post: 11902057 |
Calculation of a/c speed from audio analysis
Further to the audio analysis of a deployed RAT; given an audio print, known noise source [RAT] frequency, location of a receiver and relative location + direction of moving object, and using the principles of doppler effect etc, it should be possible to calculate [ground]speed of a passing aircraft.
Thus, having been informed that the source frequency of a RAT is 145Hz (thank you that person - please ID yourself if you wish), and with regard to the [assumed] RAT acoustic print available for AI 171 we are close to being able to determine an approximate airspeed during descent (given the video from which we get this acoustic data appears to start during the descent). There are several variables in play here that we don't know exactly (the positions of observer and aircraft, height agl of observer and aircraft etc), and some I will ignore for the moment (effect of air temperature/pressure for example) but if one makes an educated assessment from the visual cues in the video I calculate an initial relative airspeed of circa 120kn. Necessarily this is an extremely rough number, in fact the range (making various positional assumptions etc) appears to be between ~100kn to ~150kn, but if it turned out be either side of this I wouldn't be completely surprised. As with the initial audio analysis to determine whether a RAT was deployed or not I offer this for those to whom this sort of data may be important. Not sure if it's of any real use or not, and I wouldn't hang your hat on it, but here it is in case it assists. Should it matter I expect some sort of corroboration could be obtained by making an assessment of vertical speed from the variously available videos and extrapolating from there. My previous caveats over veracity of source data etc remain. FP. Last edited by First_Principal; 15th Jun 2025 at 03:17 . Reason: Update range upon further analysis - remains difficult to determine accurately Subjects: Audio Analysis RAT (All) RAT (Deployment) 1 user liked this post. |
First_Principal
2025-06-15T23:22:00 permalink Post: 11902953 |
First of all Kraftstoffvondesibel and I did our work completely without knowledge of each other. We reached the same conclusions more or less, most likely using different software (I used four different methodologies) and in subsequent discussions between us we've found our specific results (frequency etc) match very closely - including the doppler shift that we've also both commented on. While this doesn't absolutely prove the RAT scenario (I was, at least initially, somewhat more circumspect on this matter as anyone reading my first post would find) it does go some distance towards reconciling our respective methodologies and outcomes. Given the confluence and discussion I am now more satisfied that the RAT was deployed than I was before - although for the reasons espoused earlier I totally recognise the [scientific] challenges to this view. In this regard I too would not 'mind' if our view regarding RAT deployment were proven incorrect. What Kraftstoffvondesibel and I have done is simply use a little science and apply a quantitative analysis to the available data that many had qualitatively argued over. One might hope that, amongst other things, it could have dispelled the RAT/no RAT question to some degree and reduce thread noise, but unfortunately it seems some haven't read the thread through, or perhaps lack analytical reasoning. This site isn't the place for a full academic paper+peer review and for me the real subject of this thread is the tragedy of AI 171 and what might determinable from what we know in the hope it will be useful to those closer to the coal face. If you are a physicist, scientist or engineer and have the capability then the same data we used is also available to you to do your own analysis. Should you do so we'd welcome hearing the outcome - whether it concurs with our results or not - as this is the scientific way. If you want to include the full nitty-gritty detail of how you've gone about then for a very small percentage of us that might be interesting, but it'd be peripheral to the main issue - and bear in mind that RAT deployment itself is merely an indicator of other potentially more serious issues. It is not likely to be the cause per se ! To conclude, I understand it's a long thread but as far as the RAT question is concerned, I'd encourage you to read the relevant posts at least and if you remain unconvinced, and you have the skills, then why not conduct your own analysis and let us know the results? Otherwise perhaps as a group we could move on from this, remembering that this is a terrible event which at the very least deserves informed useful discussion rather than wild and/or repetitive speculation. FP. Subjects: Audio Analysis RAT (All) RAT (Deployment) 55 users liked this post. |
First_Principal
2025-06-16T00:57:00 permalink Post: 11903017 |
From the detail in this video: " Just a short video of the Boeing 787 RAT being driven by an attached hydraulic motor. This test is performed to check the RAT's hydraulic pump and electrical generator are functioning correctly. The motor that is bolted onto the back of the RAT is driven using an external hydraulic rig that is feeding the motor with hydraulic fluid at 4200psi at 40GPM ." FP. Subjects: Generators/Alternators Hydraulic Failure (All) Hydraulic Pumps RAT (All) 22 users liked this post. |
First_Principal
2025-06-16T05:22:00 permalink Post: 11903102 |
Why the RAT acoustic print is unlikely to be from a motorcycle.
There are various reasons why the signatures we obtained are not that likely to be from a motorbike, but to answer briefly - and pictures being 1000 words 'n all that - here's a quick comparative [visual] analysis. At the top is a motorbike passing by away from the observer, the other is AI 171 doing the same thing: ![]() I expect the difference will be clear. That said one could level a number of criticisms at the method I've used to show this, the sources obtained etc (eg. this is motorbike, not a moped as I couldn't find one in the time available), and if you really wanted to fake it one could, but I doubt that's occurred here. Would say more but I'm short of time and think this is sufficient clear for now. FP. Subjects: Audio Analysis 9 users liked this post. |
First_Principal
2025-06-12T22:07:00 permalink Post: 11903703 |
... Specifically, I live in Lynnwood, Washington directly under the approach path for Paine Field's runway 34 Left, and I've been there since 2007. I lived in Mukilteo from 2000-2007, which is more next to the runway than under it... Boeing manufactures the 777 and 787 at Paine field....The RAT is deployed and tested during EVERY SINGLE first flight of every aircraft Boeing produces that has a RAT installed. And sometimes it requires a re-test on subsequent flights.
So yeah, I have heard a deployed RAT, from the ground, HUNDREDS of times. I've heard it while preflighting my airplane, I've heard it while mowing my lawn, I've heard while lying in bed. And this is exactly what they always sounds like.... NOT especially getting at you slacktide , indeed thanks for the followup and presenting your experience/reasoning, however, to assist everyone, including *relevant* background/support detail with one's post is to be encouraged! If you don't have this, or are just speculating from a position of little experience or knowledge, maybe the best contribution would be to sit on your hands for a bit and learn from others? FP. Subjects: RAT (All) RAT (Deployment) 2 users liked this post. |
First_Principal
2025-06-14T09:19:00 permalink Post: 11903721 |
There has been much discussion here about RAT deployment. Various claims either way have been made, based on individual perspectives of available video and audio.
I am very mindful of just how awful a tragedy this is, and have significant misgivings about disproportionate interest in others misfortune where it carries no purpose, but also recognise that for some people knowing and learning what happened ASAP could be very important, particularly given the present circumstances. Thus while I sincerely hope that early detail from investigators will give some clarity, in an effort to reduce needless speculation regarding RAT deployment I have taken: (1) an audio sample from the video of AI171 passing by in which people claim to hear a RAT (2) an audio sample from a 787 video with RAT deployed on test by Boeing (3) an audio sample from a JAL 787 video with RAT deployed And passed these through a FFT in order to gain a more quantitative view of the noise spectra from each event. A spectrogram of the results is presented below. I hesitate to make any conclusions per se, but observe that there are similarities as well as divergences between them. In all three samples there is a relatively consistent signal roughly centered in the range 113-146Hz that could be what gives the characteristic 'buzz' sound of (apparently) a RAT in operation. JAL ~141Hz Test ~146Hz AI171 ~113-134Hz (prob doppler variation here) ![]() Spectral comparison AI171, B787 with RAT, JAL 787 with RAT ![]() Spectral comparison #2 AI171, B787 with RAT, JAL 787 with RAT These frequencies seem consistent(ish) with what I got from this video [[url]https://www.youtube.com/watch?v=O1r3CuRwjPc] in which a 787 RAT is being tested - albeit in this case the blades are hydraulically powered and not driven as a turbine. This test showed a fundamental frequency of 135Hz with relevant harmonics above (the second harmonic at 270Hz is higher SPL, no weighting): ![]() It's important to note that the initial recordings are necessarily different; these are not controlled conditions, the recording equipment is probably quite diverse and almost certainly not ideal, and the environmental conditions will also be different. Moreover all of these audio samples have come from video files referenced here, one has no way of determining the provenance or veracity of these sources and, crucially, I have no prior experience of analysing/extracting RAT acoustic fingerprints (nor have I sampled 'control' audio of a 787 passing by /without/ RAT!). Additionally it's been quite a long time since I did any work with [turbine] noise so given these and other variables I'm not prepared to make any declarations per se, but perhaps more knowledgeable people could. That said, my feeling from what I see is that RAT deployment is not dis proven, and that the apparent fundamental frequency difference between the samples may be explainable by - amongst other things - difference in a/c airspeed, bearing in mind that AI171 was on TO, the others were landing. Ultimately what I've done here is extremely rudimentary and while it would be possible to go into much more depth I'd hope that more definitive answer would be forthcoming by then, however if anyone wants to discuss specific methodology etc off-line please PM, no wish to add to noise on this thread. FP. Subjects: AI171 Audio Analysis RAT (All) RAT (Deployment) 2 users liked this post. |
First_Principal
2025-06-15T00:01:00 permalink Post: 11903723 |
Further on RAT deployment noise and acoustic analyses
Just commenting on the earlier acoustic analyses of RAT deployment conducted by
Kraftstoffvondesibel
and myself.
Firstly it will be clear that we posted our respective audio analyses about the same time. There was no collaboration I assure you, and in fact I'd been waiting all day to see if someone else with more recent or pertinent experience than me would do something. When I hadn't seen anything I spent a little time and came up with what I did, however I think Kraftstoffvondesibel's work is probably more useful than mine given their specific plot methodology and that they included a non-RAT 'control' pass. I was in the process of acknowledging this when the thread was closed; late at night for me which is why this post is now some hours on. At the time I posted I was fairly circumspect for the reasons given but, with the similarities between our results and along with some other detail that's come to light in PM, I am now more persuaded that the acoustic print we both observed is most likely to be from a RAT (although until this is confirmed a question must necessarily remain). FWIW, and in part answer to a later post enquiring about the noise of a RAT dropping into position, this also aligns somewhat with the survivor's apparent observation of a noise ('bang'?) prior to impact, and an earlier post by DaveReidUK stating that RAT deployment results in a 'humungous' bang. FP. Subjects: RAT (All) RAT (Deployment) Thread Closure |
First_Principal
2025-06-15T02:23:00 permalink Post: 11903724 |
Calculation of a/c speed from audio analysis
Further to the audio analysis of a deployed RAT; given an audio print, known noise source [RAT] frequency, location of a receiver and relative location + direction of moving object, and using the principles of doppler effect etc, it should be possible to calculate [ground]speed of a passing aircraft.
Thus, having been informed that the source frequency of a RAT is 145Hz (thank you that person - please ID yourself if you wish), and with regard to the [assumed] RAT acoustic print available for AI 171 we are close to being able to determine an approximate airspeed during descent (given the video from which we get this acoustic data appears to start during the descent). There are several variables in play here that we don't know exactly (the positions of observer and aircraft, height agl of observer and aircraft etc), and some I will ignore for the moment (effect of air temperature/pressure for example) but if one makes an educated assessment from the visual cues in the video I calculate an initial relative airspeed of circa 120kn. Necessarily this is an extremely rough number, in fact the range (making various positional assumptions etc) appears to be between ~100kn to ~150kn, but if it turned out be either side of this I wouldn't be completely surprised. As with the initial audio analysis to determine whether a RAT was deployed or not I offer this for those to whom this sort of data may be important. Not sure if it's of any real use or not, and I wouldn't hang your hat on it, but here it is in case it assists. Should it matter I expect some sort of corroboration could be obtained by making an assessment of vertical speed from the variously available videos and extrapolating from there. My previous caveats over veracity of source data etc remain. FP. Subjects: Audio Analysis RAT (All) RAT (Deployment) |
First_Principal
2025-06-15T23:22:00 permalink Post: 11903726 |
First of all Kraftstoffvondesibel and I did our work completely without knowledge of each other. We reached the same conclusions more or less, most likely using different software (I used four different methodologies) and in subsequent discussions between us we've found our specific results (frequency etc) match very closely - including the doppler shift that we've also both commented on. While this doesn't absolutely prove the RAT scenario (I was, at least initially, somewhat more circumspect on this matter as anyone reading my first post would find) it does go some distance towards reconciling our respective methodologies and outcomes. Given the confluence and discussion I am now more satisfied that the RAT was deployed than I was before - although for the reasons espoused earlier I totally recognise the [scientific] challenges to this view. In this regard I too would not 'mind' if our view regarding RAT deployment were proven incorrect. What Kraftstoffvondesibel and I have done is simply use a little science and apply a quantitative analysis to the available data that many had qualitatively argued over. One might hope that, amongst other things, it could have dispelled the RAT/no RAT question to some degree and reduce thread noise, but unfortunately it seems some haven't read the thread through, or perhaps lack analytical reasoning. This site isn't the place for a full academic paper+peer review and for me the real subject of this thread is the tragedy of AI 171 and what might determinable from what we know in the hope it will be useful to those closer to the coal face. If you are a physicist, scientist or engineer and have the capability then the same data we used is also available to you to do your own analysis. Should you do so we'd welcome hearing the outcome - whether it concurs with our results or not - as this is the scientific way. If you want to include the full nitty-gritty detail of how you've gone about then for a very small percentage of us that might be interesting, but it'd be peripheral to the main issue - and bear in mind that RAT deployment itself is merely an indicator of other potentially more serious issues. It is not likely to be the cause per se ! To conclude, I understand it's a long thread but as far as the RAT question is concerned, I'd encourage you to read the relevant posts at least and if you remain unconvinced, and you have the skills, then why not conduct your own analysis and let us know the results? Otherwise perhaps as a group we could move on from this, remembering that this is a terrible event which at the very least deserves informed useful discussion rather than wild and/or repetitive speculation. FP. Subjects: Audio Analysis RAT (All) RAT (Deployment) 7 users liked this post. |
First_Principal
2025-06-16T00:57:00 permalink Post: 11903734 |
From the detail in this video: " Just a short video of the Boeing 787 RAT being driven by an attached hydraulic motor. This test is performed to check the RAT's hydraulic pump and electrical generator are functioning correctly. The motor that is bolted onto the back of the RAT is driven using an external hydraulic rig that is feeding the motor with hydraulic fluid at 4200psi at 40GPM ." FP. Subjects: Generators/Alternators Hydraulic Failure (All) Hydraulic Pumps RAT (All) 4 users liked this post. |
First_Principal
2025-06-16T05:22:00 permalink Post: 11903741 |
Why the RAT acoustic print is unlikely to be from a motorcycle.
There are various reasons why the signatures we obtained are not that likely to be from a motorbike, but to answer briefly - and pictures being 1000 words 'n all that - here's a quick comparative [visual] analysis. At the top is a motorbike passing by away from the observer, the other is AI 171 doing the same thing: ![]() I expect the difference will be clear. That said one could level a number of criticisms at the method I've used to show this, the sources obtained etc (eg. this is motorbike, not a moped as I couldn't find one in the time available), and if you really wanted to fake it one could, but I doubt that's occurred here. Would say more but I'm short of time and think this is sufficient clear for now. FP. Subjects: Audio Analysis 1 user liked this post. |
First_Principal
2025-06-18T02:51:00 permalink Post: 11904853 |
Lest we forget...
I spent some time this morning doing a further quantitative analysis of the flight path of AI171, however I've come to the view that is of little real use to anyone, so I won't be presenting it at this time.
What I do want to say though, particularly after what I saw much earlier this morning, and what I recently read about the young man who took the video many have seen, is a heartfelt acknowledgment to anyone reading this thread who is a survivor, witness, relative, responder, or simply anyone directly affected by this tragedy. As someone who, unfortunately, has been in a not-dissimilar situation I want to tell you that it's *not* your fault , that it's normal to feel angry, or guilty, or sad, or even not to be able to feel anything at all. It's ok to want to cry at the oddest of moments, to want to kick the hell out of something, to be unable to sleep - or to just to curl up and go to sleep for a long time. This could hit you weeks from now, or it may never happen at all, it will worry you when it does - or not - but y'know, strangely, that's ok too. We can rarely control such strong emotion, it's simply the way we frail humans work, and we don't all feel, or express things, in the same way. People will tell you that time heals all. You may not believe that right now, and most of us will never be able to unfeel, unsee, unhear, or unsmell, but the passage of time will ease these things. It may take years, or not, but it's ok, there is a future. If you know someone that's involved, give them a hug, or don't give them a hug if that's what they need too. Space, peace, quiet, or conversely keeping really busy at work with people around are all mechanisms different people may use to cope. Keeping a watching eye and 'being right there' if/when you're needed is perhaps the best thing you can do, along with understanding if that person wants distance. And, it might seem unbelievably crass that we're discussing what happened to you, to your friends or relatives, but for some of us it's our way of helping - or coping - when we feel your tragedy so strongly. It's a practical way we can help ourselves and others understand, or learn, or even prevent someone else suffering the same way. There will be people on this forum who get this more keenly than others, but no-one intends to hurt. For those that are interacting here, it behooves us all to be aware of the humanity, to remember before we say anything that real people are hurting right now, and that on this public forum whatever we say could be read by anyone at any time, forever. Sincerely, FP. Subjects: AI171 29 users liked this post. |
First_Principal
2025-06-21T08:19:00 permalink Post: 11907566 |
"Boeing explained that the RAT will remain operational as the airplane decelerates through the minimum RAT design speed of 120 knots, not 130 knots. Boeing expressed that the performance of the RAT was shown to meet the Boeing Model 787 requirement that specifies 120 knots as the minimum RAT design speed. We agree that the RAT will remain operational as the airplane decelerates through the minimum RAT design speed of 120 knots, not 130 knots..." Again I'm not sure this is of any particular utility now, but is included here in the interests of ensuring as much factual data is available as possible. FP. Subjects: ADSB Audio Analysis FAA Lift/Drag Ratio RAT (All) Total Energy 5 users liked this post. |
First_Principal
2025-06-22T01:06:00 permalink Post: 11908202 |
Just in case it wasn't obvious, JustusW managed to make an excellent point twice in their post about FPGA's, software and bugs.
The above code has a bug, which I assume was deliberate in order to see how many of us were really reading what they had to say, and to drive that home. Well done you, it is a simple illustration of just how easy it is for issues to slip through and not be noticed. While this simple bug would have been picked up early on by a compiler there could well be other much more esoteric and subtle bugs that could take years in operation and require a very specific set of circumstances before they trip. I make no comment or assertion that's the case here for AI 171, but it is worth bearing in mind in any search for understanding and cause. FP. Subjects: None 7 users liked this post. |
First_Principal
2025-06-22T02:12:00 permalink Post: 11908230 |
Quite. Didn't want to get too literal, rather more thought it worth illustrating the point was well made and how it
might
be relevant here.
Also of interest was JustusW's assertion that FPGA's were potentially utilised in the system under discussion. I don't know if that's an authoritative view but you have well underlined some of the issues they could bring. FP. Subjects: None |
First_Principal
2025-06-28T05:47:00 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. Subjects: CVR DFDR EAFR FDR NTSB V1 3 users liked this post. |
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