June 16, 2025, 09:48:00 GMT
permalink Post: 11903685
One thing we haven't discussed as a characteristic is how the AI recording moves from indirect sound with a shorter ambience, to direct sound, to a very much more ambient distant character in the same amount of time as the large aircraft moving overhead.
The moped/motorcycle in the sample, keeps about the same small street ambience throughout.
Notice how the harmonics are in different places with different spacing and with different relative intensity, the emphasis on the internal combustion engine is lower in frequency than the open Rat, but with added exhaust noise.
Thank you.
I also enclose a doppler distance
Subjects: None
June 14, 2025, 09:18:00 GMT
permalink Post: 11903720
I hesitate to chip in in these accident threads. Keep them clean. However, as as a few comments above brushes my audio expertise, I will comment.
A very simple audio analysis give me this:
The 3 segments horisontally, are of different videos of B787s passing overhead/landing. The vertical drop you see is the doppler effect.
In other words, these are spectrograms over time which makes these distinctions easier than a simple static spectrogram.
1. B787 landing with RAT extended.
2.Air india crash
3. B787 landing without RAT
It's a 5 minute laptop job, and it would look much prettier and clearer if I spent some time with it, (Gain to color match, and spectrally match to compensate for microphone placement and type),
but it is 85% conclusive even when done as simple as this IMO.
(I do have legal forensic audio experience)
The RAT was out judging from the audio evidence. You can see the the equally spaced overtones of the propelller match when passing overhead resulting in the Doppler effect, the difference in length of the doppler is caused by distance and the slightly varying frequencies shown in the starting point is caused by a difference in speed. But the harmonic content match.
In the 3rd segment you see none of these overtones at all.
A very simple audio analysis give me this:
The 3 segments horisontally, are of different videos of B787s passing overhead/landing. The vertical drop you see is the doppler effect.
In other words, these are spectrograms over time which makes these distinctions easier than a simple static spectrogram.
1. B787 landing with RAT extended.
2.Air india crash
3. B787 landing without RAT
It's a 5 minute laptop job, and it would look much prettier and clearer if I spent some time with it, (Gain to color match, and spectrally match to compensate for microphone placement and type),
but it is 85% conclusive even when done as simple as this IMO.
(I do have legal forensic audio experience)
The RAT was out judging from the audio evidence. You can see the the equally spaced overtones of the propelller match when passing overhead resulting in the Doppler effect, the difference in length of the doppler is caused by distance and the slightly varying frequencies shown in the starting point is caused by a difference in speed. But the harmonic content match.
In the 3rd segment you see none of these overtones at all.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): RAT (All) RAT (Deployment)
June 17, 2025, 10:10:00 GMT
permalink Post: 11904165
So, also as an outsider when it comes to cockpit engineering, there is one commmon "system" in the sense of the very close physical location, the two engine systems have in common, and that is the physical cut off switches and their behind the panel connections.
It wouldn't take a kids pool of liquid to intefere with those?
(I asked this question previuously, in the middle of a long text, but the discussion had a very different direction then.)
What are possible ways of a common failure/triggering of these contact points somewhere in their physical installation in the cockpit?
Remember when the A350 had to be modified only 5 years ago to not allow coffee spill to turn off engines.
What about the same location in the B787?
What are the actual switches? Are they purely traditional electromechanical contact switches? How do they make contact, ie. what are the actual gaps and dimensions? Are they digital in some sense? How are they protected? Are both installed the exact same way, or are they installed with different physical screening/protection/orientation as so to make the failure modes different? How are they physically kept apart, isolated from each other to avoid interaction and/or common failure. What is the physical distance involved there? What about the cables and connectors to them? separate or bundled in the same wiring harness? Or even in Mil or D-sub connectors? I find one description of them as a common(both in one box) line replaceable unit with quick connects. Both of them in the same unit with a common connector? Sounds wild if so!
Just had to ask, and hope it doesn't disturb the great discussion too much.
It wouldn't take a kids pool of liquid to intefere with those?
(I asked this question previuously, in the middle of a long text, but the discussion had a very different direction then.)
What are possible ways of a common failure/triggering of these contact points somewhere in their physical installation in the cockpit?
Remember when the A350 had to be modified only 5 years ago to not allow coffee spill to turn off engines.
What about the same location in the B787?
What are the actual switches? Are they purely traditional electromechanical contact switches? How do they make contact, ie. what are the actual gaps and dimensions? Are they digital in some sense? How are they protected? Are both installed the exact same way, or are they installed with different physical screening/protection/orientation as so to make the failure modes different? How are they physically kept apart, isolated from each other to avoid interaction and/or common failure. What is the physical distance involved there? What about the cables and connectors to them? separate or bundled in the same wiring harness? Or even in Mil or D-sub connectors? I find one description of them as a common(both in one box) line replaceable unit with quick connects. Both of them in the same unit with a common connector? Sounds wild if so!
Just had to ask, and hope it doesn't disturb the great discussion too much.
Last edited by Kraftstoffvondesibel; 17th June 2025 at 10:34 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches
June 18, 2025, 23:36:00 GMT
permalink Post: 11905621
But what about whats inside and behind the switches? How is the signals from them transmitted to the valves? Analog? Digital? Software? They seem to be part of the same LRU, what does it look like on the inside? same multi-cable harness too? Same multi-connector? I believe this has not been touched upon.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Switch Guards
June 19, 2025, 12:16:00 GMT
permalink Post: 11905976
Switches fail sometimes. I have changed lots of lots of malfunctioning toggle switches in my day.
But both at the same time?
It has to be a common thing happening at the same time.
Someone slipping both switches into a worn middle detent is such a thing though, that is one habit that could be developed. A slight bump at takeoff and they both go to cutoff.
Or they are worn and theres an iphone behind the throttles, as someone mentioned.
The switches themselves are on-on 4 pole toggles, and doesn\x92t fail into one position over the other, and gravity would prefer the cutoff position in this design.
I mentioned I have used my share of switches, knobs and buttons. In much larger quantities than what you find in aircraft, but without the life and death factor, and thus no SOP.
Unexpected things happen, no one dies, but I myself brodcasted jolly sounding very inappropriate intro music over a very dark news report on the unravelling Joseph Frietzl case by dropping my phone on a switch. Several million viewers, a good chunk of which called to complain.
Grave errors can be banal.
Other than that, common connectors, the harness itself, I have seen a large amount of unexpected electronic things happen when those get bendt the wrong way.
Last edited by Kraftstoffvondesibel; 19th June 2025 at 12:30 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches Fuel Cutoff Switches (detent)
June 19, 2025, 12:33:00 GMT
permalink Post: 11905988
Absolutely. Like a badly tightened connector, or a harness short waiting to happen. I only mentioned some possibilities.
Subjects: None
June 19, 2025, 12:47:00 GMT
permalink Post: 11905992
I guess it depends on the model, as there are three position versions where the center position is valid, but that uses a different cam profile. For the one here, just confirmed, the toggle always finds one side or the other. The cam profile is circular, and it doesn't seem possible to balance in the middle. The cam section is separate to the threaded section. Might be a press fit initially, but is also staked either side. Have seen one of these where the cam section was loose, but still not possible to override the cam. A simple, but very effective bit of design work, IMHO.
Subjects: None
June 19, 2025, 12:56:00 GMT
permalink Post: 11906002
The extended
spec sheet
for these switches shows that there are versions with a center indent, and others without. But the
picture up above
which is said to be of the 787/8 actual switch seems - to me - to
not
have a center indent option. Ie, it is either on or off, with a spring loaded lift of about 2mm needed to move it from one position to another.
It seems the design, function and placement of these switches might have been \x93grandfathered\x94 over several generations of cockpit design.
Subjects: None
June 19, 2025, 16:28:00 GMT
permalink Post: 11906174
(re:skwdenier and the photo of the switch. )
And those wires, which all i can find points to having (non-english speaker) screw terminals. within the LRU shared by both switches. Those things go bad over time even when installed in non-movable equipment.
For those that argue that these are some kind of very special switches. They aren't. Sure they are really nice switches, but that series is available through normal distributors like mauser or elfa-distrelec in europe for, and the price isn't sensationally high compared to other switches.
I am curious as to how the LED light power is threaded through to the switch top. Why do they have a LED, in the first place? Seems a bit gimmicky.
Since they have such inherent damage potential in systems that are otherwise carefully isolated through redundancies and physical seperation, why aren't they? Why aren't the 2 cut off switches placed in 2 different locations in the cockpit. Seems like such a cheap insurance.
Sorry if I am adding noise, I know these are just one of many possibilities, and I am not knowledgeable enough to weigh these different theories against each other, but this switch thing is just something I know personally have more failure potential than what I thought were acceptable for this application.
And those wires, which all i can find points to having (non-english speaker) screw terminals. within the LRU shared by both switches. Those things go bad over time even when installed in non-movable equipment.
For those that argue that these are some kind of very special switches. They aren't. Sure they are really nice switches, but that series is available through normal distributors like mauser or elfa-distrelec in europe for, and the price isn't sensationally high compared to other switches.
I am curious as to how the LED light power is threaded through to the switch top. Why do they have a LED, in the first place? Seems a bit gimmicky.
Since they have such inherent damage potential in systems that are otherwise carefully isolated through redundancies and physical seperation, why aren't they? Why aren't the 2 cut off switches placed in 2 different locations in the cockpit. Seems like such a cheap insurance.
Sorry if I am adding noise, I know these are just one of many possibilities, and I am not knowledgeable enough to weigh these different theories against each other, but this switch thing is just something I know personally have more failure potential than what I thought were acceptable for this application.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches
June 19, 2025, 16:48:00 GMT
permalink Post: 11906185
The
datasheet
does mention:
I guess the pictured wires may be the latter option, which would hopefully be more vibration-resistant than screw terminals (or solder lugs).
It's my understanding the LED in the switch illuminates in case of engine fire indication. In that case, it may be a way to reduce the chance of shutting down the incorrect engine.
I guess the pictured wires may be the latter option, which would hopefully be more vibration-resistant than screw terminals (or solder lugs).
It's my understanding the LED in the switch illuminates in case of engine fire indication. In that case, it may be a way to reduce the chance of shutting down the incorrect engine.
Subjects: None
June 19, 2025, 23:16:00 GMT
permalink Post: 11906475
If so , the likelyhood of this having anything to do with the switches, their harness, or connectors drops way down. (although most theories are dealing with statistical "impossibilities", what better time than after decades for such to occur.)
The switches are double on's or 4 pole, that means they are (can be) connected to 2 different systems individually. Anyone know how that system looks? Why 2 signals?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FADEC Fuel (All) Fuel Cutoff Fuel Cutoff Switches
June 20, 2025, 16:36:00 GMT
permalink Post: 11907117
Regarding the Recorders, obviously nothing to do with the cause, but still:
Given:
There were 2 recorders:
1/in the tail, likely to not be overly damaged, but might have stopped being powered at the moment the thrust was lost. Due to digital delay, it might not have catched interesting transient data of the cause.
It is too far removed from the cockpit to have independent analog feeds from microphones or other equipment.
2/ The one in the front, much more likely to have been damaged, and also more likely to be useful because it had an independent area microphone cockpit source.
I have 2 questions and a speculation:
Speculation: The front recorder also lost all data because the systems powered down, except it independently, and by analog direct means, powers the cockpit area microphone w/micpre and could continue recording that for a good amount of time on a small battery.
This then might be the recorder recieving special treatment and delayed read out, because of the damage, and because it contains audio from the cockpit, (while the other one, might already have been read by conventional means, but doesn't contain anything of use because this was a sudden event and digital latency. Or as I assume some might speculate, the tail recoder hinted to information leaving the decision on whether to read the front recorder abroad to someone much higher up)
Questions:
1/Would the recorders lose access to aircraft data streams when engine power is lost, at least temporarely making the cockpit area mic recorded by battery power on the front recorder the only source of information ?
2/The recorders only draw 20W, why is it the front have reserves only for 10 minutes? Can you even buy a battery that small giving 28VDC? Why is such a limited solution selected?
(And since they have a microphone input, and the units are interchangeable why don't they just stick a few grams worth of microphone in the back of the aircraft as well, just to catch mechanical noises that could help when data input is missing. Audio sensors seems underrated.)
( For reference, This battery could power the whole recorder for an hour: https://www.batteryspace.com/custom-nimh-battery-28-8v-800mah-23wh-with-tabs.aspx )
Given:
"The forward installed EAFR along with theCockpit Area Microphone and Preamplifier are typically connected to the Recorder Independent Power Supply (RIPS), providing a backup power source for 10 minutes in the event of power interruptions."
1/in the tail, likely to not be overly damaged, but might have stopped being powered at the moment the thrust was lost. Due to digital delay, it might not have catched interesting transient data of the cause.
It is too far removed from the cockpit to have independent analog feeds from microphones or other equipment.
2/ The one in the front, much more likely to have been damaged, and also more likely to be useful because it had an independent area microphone cockpit source.
I have 2 questions and a speculation:
Speculation: The front recorder also lost all data because the systems powered down, except it independently, and by analog direct means, powers the cockpit area microphone w/micpre and could continue recording that for a good amount of time on a small battery.
This then might be the recorder recieving special treatment and delayed read out, because of the damage, and because it contains audio from the cockpit, (while the other one, might already have been read by conventional means, but doesn't contain anything of use because this was a sudden event and digital latency. Or as I assume some might speculate, the tail recoder hinted to information leaving the decision on whether to read the front recorder abroad to someone much higher up)
Questions:
1/Would the recorders lose access to aircraft data streams when engine power is lost, at least temporarely making the cockpit area mic recorded by battery power on the front recorder the only source of information ?
2/The recorders only draw 20W, why is it the front have reserves only for 10 minutes? Can you even buy a battery that small giving 28VDC? Why is such a limited solution selected?
(And since they have a microphone input, and the units are interchangeable why don't they just stick a few grams worth of microphone in the back of the aircraft as well, just to catch mechanical noises that could help when data input is missing. Audio sensors seems underrated.)
( For reference, This battery could power the whole recorder for an hour: https://www.batteryspace.com/custom-nimh-battery-28-8v-800mah-23wh-with-tabs.aspx )
Last edited by T28B; 20th June 2025 at 18:25 . Reason: formatting
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Cockpit Area Audio EAFR RIPS
June 20, 2025, 19:10:00 GMT
permalink Post: 11907217
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
It is likely a mems-type microphone, moving coil, ribbon or traditional condenser microphones aren’t really used outside the stage or vintage recording studios these days. But something along these lines: https://pdf.aeroexpo.online/pdf/l3-t...html#open64169
Note the dual analog and arinc digital outputs.
One reason for not doing an analog line all the way to the tail would be weight, as you mention, quality or noise wouldn’t be an issue due common mode rejection.
Last edited by T28B; 20th June 2025 at 19:11 . Reason: punctuation and grammar assist
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air Worthiness Directives CVR Cockpit Area Audio EAFR
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?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR Electrical Failure Generators/Alternators NTSB RAT (All) RIPS Thread Moderation
June 26, 2025, 21:38:00 GMT
permalink Post: 11911518
Not quite sure if this thread is open again or not.
I wanted to bring something up.
Maybe I am out of touch, but the way we have talked about this accident, we have talked about it like it were doomed to be an unsurviveable high energy crash inferno.
I, at least, have been guilty of having this picture in my mind.
Wasn't this a, relatively speaking, a low energy impact scenario, comparable to Air France 269, SAS 751, BA038, or a number of other accidents including things like the hudson river event, which would have been somewhat surviveable except the impact with the buildings?
There looks to be more open areas in close proximity to the accident site that are as big, 150-250 meters, or larger than what either of those others had available or at least used.
There have been comments of the docile trajectory of the aircraft being a sign of pilots giving up, and letting automation take over of sorts, but in reality, could it be they just did exactly the same as the crew on BA038 or SAS 751? Except the lack of luck?
In connection with this, why would the recorders be so damaged it has taken them weeks to access them. It seems that kind of impact should be well within the envolope for those designs.
If out of bounds or order, please delete.
I wanted to bring something up.
Maybe I am out of touch, but the way we have talked about this accident, we have talked about it like it were doomed to be an unsurviveable high energy crash inferno.
I, at least, have been guilty of having this picture in my mind.
Wasn't this a, relatively speaking, a low energy impact scenario, comparable to Air France 269, SAS 751, BA038, or a number of other accidents including things like the hudson river event, which would have been somewhat surviveable except the impact with the buildings?
There looks to be more open areas in close proximity to the accident site that are as big, 150-250 meters, or larger than what either of those others had available or at least used.
There have been comments of the docile trajectory of the aircraft being a sign of pilots giving up, and letting automation take over of sorts, but in reality, could it be they just did exactly the same as the crew on BA038 or SAS 751? Except the lack of luck?
In connection with this, why would the recorders be so damaged it has taken them weeks to access them. It seems that kind of impact should be well within the envolope for those designs.
If out of bounds or order, please delete.
Subjects: None
June 28, 2025, 20:11:00 GMT
permalink Post: 11912650
I think we have been through this several times just over the last few pages of the thread: the (front)recorder is battery powered for ten minutes, and it also independently powers, amplifies and records a cockpit area mic through it\x92s analog input. The recorder\x92s power consumption is only given for the unit as a whole and is incredibly low. You can hardly find a commercially available battery that is too small to power the thing for 10 minutes.
What potential other data reaches the recorder to be recorded in the first place in a emergency power situation, is the relevant question that has been asked about 30 different ways, but has not been answered. It might be none.
What potential other data reaches the recorder to be recorded in the first place in a emergency power situation, is the relevant question that has been asked about 30 different ways, but has not been answered. It might be none.
Subjects: None
June 29, 2025, 17:40:00 GMT
permalink Post: 11913148
Sabotage on the electrical fuels shut down:
Would require detailed knowledge about the wire routing, which is independent for both engine sides, so any "device" would be difficult to get into the electric harness. I would rule that out, unless they find foreign devices wired in on the wreck, because there are way simpler methods to get an airliner down.
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Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches
June 30, 2025, 23:23:00 GMT
permalink Post: 11913943
I did not find good enough material to compare to, and time was lacking a bit.
There is engine noise, or engine-like noise from there, somewhat comparable to an engine at idle, that fades out into the background noise at the same rate as the RAT. I don\x92t know if it comes from an engine at idle, windmilling, an engine producing some power, or if it is even just aerodynamic noise from the rest of the airframe.
I\x92ll give it another go if time allows.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): RAT (All)
July 10, 2025, 12:31:00 GMT
permalink Post: 11918989
The switch itself is 4-pole, or a double-on, double-on switch, capable of independentently signaling whrough completely isolated poles. The plot thickens. IF the switches really are involved, there is either some kind of shortcut in within the LRU/very messed up witing harness, some freak automated muscle memory thing or deliberate action.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Fuel Cutoff Switches Muscle Memory Spar Valves
July 11, 2025, 20:46:00 GMT
permalink Post: 11919773
So, yes, switches.
either
1/deliberately cut off by someone in the cockpit, or
2/placed in an intermediate gate position possible due to wear or wrong installation, happens during engine start, and then vibrates or bumps to cut-off during the take off roll or
3/some kind of liquid or other contamination in the LRU shorting both and cycling them after 8 seconds brought them electrically back to RUN.
Anyone got other ideas?
either
1/deliberately cut off by someone in the cockpit, or
2/placed in an intermediate gate position possible due to wear or wrong installation, happens during engine start, and then vibrates or bumps to cut-off during the take off roll or
3/some kind of liquid or other contamination in the LRU shorting both and cycling them after 8 seconds brought them electrically back to RUN.
Anyone got other ideas?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches RUN/CUTOFF