Posts about: "RAT (All)" [Posts: 607 Pages: 31]

1stspotter
2025-06-14T18:27:00
permalink
Post: 11901706
Originally Posted by Compton3fox
We can debate over a poor quality photo but the audio evidence presented earlier today is pretty conclusive.. The RAT was out.
Extremely likely the RAT was out:

1. there are multiple frames of the video showing ' something' at the position where the RAT is located under the fuselage
2. the sound in the video which is very similar to a deployed RAT
3. the sound analysis posted here by multiple people
last but not least
4. the aircraft stopped transmitting ADSB data shortly after the rotating. This indicates an electrical failure. Other aircraft ADSB data was picked up by FR24 receivers indication there is a good reception of the signal in that area.

8 users liked this post.

fdr
2025-06-14T18:52:00
permalink
Post: 11901729
Originally Posted by Kraftstoffvondesibel
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.
Originally Posted by Compton3fox
That leads to the next question.. Is there any system on the 787 that CAN shutdown the engines. We know there is at least one... But the A/C needs to be ground mode. However, if would not be the 1st time a system that should not deploy when the A/C is airborne, does! LaudaAir out from BKK is one example...
Agree with most of your comments, but Lauda 004, the B763ER/PW4060 aircraft, no evidence was developed to indicate a G/A sensing fault. The report is available on line,

Lauda Air B767 Accident Report

Lauda 004 taught that the flight test of reverse had some assumptions that were not accurate. The reduction in lift from the flow interaction with the wing was not recognised before Lauda 004, and before that was discovered, there were a lot of flight departments that were rather judgemental of the event due to their own ignorance. Just because our sims say it is so doesn't mean that the aircraft agrees.

Investigation of the accident disclosed that certain "hot-short" conditions involving the electrical system occurring during an auto-restow command, could potentially cause the DCV to momentarily move to the deploy position. However, no specific wire or component malfunction was physically identified that caused an uncommanded thrust reverser deployment on the accident airplane.

Testing identified hypothetical hydraulic system failures that could cause the thrust reverser to deploy. However, no specific component malfunction was identified that caused an uncommanded thrust reverser deployment on the accident airplane.

No specific Lauda Air maintenance action was identified that caused uncommanded thrust reverser deployment on the accident airplane.

The design changes recommended by Boeing and thereafter mandated by U.S. Federal Aviation Administration Airworthiness Directive 91-22-09 for the B767/PW4000 thrust reverser system should effectively prevent in-flight deployment even after multiple failures.
Shep69
2025-06-14T19:26:00
permalink
Post: 11901751
Originally Posted by go-around flap 15
We're all shouting each other down with two main different theories on why the aircraft lost lift so shortly after takeoff.

1) Incorrect flap retraction causing the aircraft to lose lift and unable to recover the energy in time. (Not unheard of and plenty of reports where this has happened - albeit usually not to a crash).

2) Loss of engine thrust backed up two potential pieces of evidence that back up the RAT was deployed (apparent RAT sound, potential RAT seen on low res video).

It is impossible to know which of these is the case. Considering this summary of memory items is there the potential for a combination of both theories to have taken place?

Inadvertant flap retraction by PNF leading the PF to sense a sink and loss of lift. Pushes the thrust levers forward to the firewall and still the aircraft sinks. PF looking through the HUD and so very much 'outside focused' and doesn't realise that PNF has instead moved the flaps. PF defaults to memory items for loss of thrust on both engines before PNF can realise or communicate to PF what they've done, start switches are cut off which drops the RAT and from that point they're only heading one way. This would satisfy the strongly held belief that the RAT was extended, whilst also following the more likely initial cause of an action slip by PNF starting the sequence, rather than a dual engine failure.
This to me makes more sense; perhaps I`ve got it wrong but in the video the trailing edge flaps definitely look up. Maybe there`s more and they weren`t.

On a flap 5 takeoff the FMS could be programmed to select climb power at flaps 1 which would seem like an apparent loss of thrust. Same as for F15 to F5 or further.

I`m not sure if they would have cycled the FCS switches or not. But the airplane certainly would have experienced a loss of lift would the flaps been inadvertently retracted. As well as perceived loss of thrust.

OTOH any castastophic failure which left the gear down would have essentially left the flaps where they were. They are hydraulically activated with electrical backup but it`s wayyyyy slow.
Flatiron220
2025-06-14T19:59:00
permalink
Post: 11901781
Standard SLF disclaimer goes here-

I\x92m +1 for the RAT theory- having watched the video numerous times on phone speakers and headphones, the noise as the aircraft flies over the balcony is very strongly reminiscent of hearing T-6s (fast propeller aircraft) at an air cadet camp at Valley a few years back and, having recently been at the Frankfurt airport viewing deck, nowhere close to the noise I\x92ve heard from a departing Dreamliner. They\x92re quiet aircraft but not that quiet!

One more pondering and I apologise for this\x85 a recent BA flight into LHR had the captain rapidly flashing the seatbelt sign during his welcome announcement, explaining that if he did this we should return to our seats immediately. Eyewitness testimony is famously unreliable, and the \x91flickering\x92 of the green exit lights could mean many different things. Dreamliner drivers, you are the experts. Is it plausible that the flight deck crew could have tried to flash the emergency lights in lieu of a \x91brace for impact\x92 call similar to the ONA ditching in the Caribbean?
GANovice
2025-06-14T20:30:00
permalink
Post: 11901803
Originally Posted by Flatiron220
Standard SLF disclaimer goes here-

I\x92m +1 for the RAT theory- having watched the video numerous times on phone speakers and headphones, the noise as the aircraft flies over the balcony is very strongly reminiscent of hearing T-6s (fast propeller aircraft) at an air cadet camp at Valley a few years back and, having recently been at the Frankfurt airport viewing deck, nowhere close to the noise I\x92ve heard from a departing Dreamliner. They\x92re quiet aircraft but not that quiet!

One more pondering and I apologise for this\x85 a recent BA flight into LHR had the captain rapidly flashing the seatbelt sign during his welcome announcement, explaining that if he did this we should return to our seats immediately. Eyewitness testimony is famously unreliable, and the \x91flickering\x92 of the green exit lights could mean many different things. Dreamliner drivers, you are the experts. Is it plausible that the flight deck crew could have tried to flash the emergency lights in lieu of a \x91brace for impact\x92 call similar to the ONA ditching in the Caribbean?
No.

Flashing the seatbelt lights to get people back to their seat quicker, while somewhat unreliable, is for doing exactly that.

It is not to tell the passengers to brace for impact! That\x92s ridiculous.
NWSRG
2025-06-14T20:36:00
permalink
Post: 11901810
Originally Posted by kristofera
Just a thought regarding the possibility of some kind of sensor failure: mud wasps.

Since this was a short stopover, perhaps pitot covers were not used. Mud wasps can build their nests in a very short timespan, and they have been known to block pitot tubes and static pitot ports in the past.

Just throwing this out there as one additional possible hole in one of the slices of cheese.
This thought had crossed my mind...but then the RAT suggests a loss of the electrical system. And I'm not sure how the two could be linked?

2 users liked this post.

Flatiron220
2025-06-14T20:40:00
permalink
Post: 11901814
Originally Posted by NWSRG
This thought had crossed my mind...but then the RAT suggests a loss of the electrical system. And I'm not sure how the two could be linked?
Others have been asking if there were potentially a number of deferred items on the MEL, not the most outlandish possibility given some of the AI stories on here and elsewhere. But as you\x92ve said, a failure mode that goes from blocked pitots to a dual engine failure at takeoff sounds like the plot of a bad film
tdracer
2025-06-14T20:48:00
permalink
Post: 11901821
Another hour spent sifting through the stuff since last night (my sympathies to the mods ). A few more comments:

"Real time engine monitoring" is typically not 'real time' - it's recorded and sent in periodic bursts. Very unlikely anything was sent from the event aircraft on this flight.

Commanded engine cutoff - the aisle stand fuel switch sends electrical signals to the spar valve and the "High Pressure Shutoff Valve" (HPSOV) in the Fuel Metering Unit, commanding them to open/close using aircraft power. The HPSOV is solenoid controlled, and near instantaneous. The solenoid is of a 'locking' type that needs to be powered both ways (for obvious reasons, you wouldn't want a loss of electrical power to shut down the engine). The fire handle does the same thing, via different electrical paths (i.e. separate wiring).

As I've noted previously, a complete loss of aircraft electrical power would not cause the engines to flameout (or even lose meaningful thrust) during takeoff. In the takeoff altitude envelope, 'suction feed' (I think Airbus calls it 'gravity feed') is more than sufficient to supply the engine driven fuel pumps. It's only when you get up to ~20k ft. that suction feed can become an issue - and this event happened near sea level.

Not matter what's happening on the aircraft side - pushing the thrust levers to the forward stop will give you (at least) rated takeoff power since the only thing required from the aircraft is fuel and thrust lever position (and the thrust lever position resolver is powered by the FADEC).

The TCMA logic is designed and scrubbed so as to be quite robust - flight test data of the engine response to throttle slams is reviewed to insure there is adequate margin between the TCMA limits and the actual engine responses to prevent improper TCMA activation. Again, never say never, but a whole lot would have had to go wrong in the TCMA logic for it to have activated on this flight.

Now, if I assume the speculation that the RAT deployed is correct, I keep coming up with two potential scenarios that could explain what's known regarding this accident:
1) TCMA activation shutdown the engines
or
2) The fuel cutoff switches were activated.
I literally can come up with no other plausible scenarios.

In all due respect to all the pilots on this forum, I really hope it wasn't TCMA. It wouldn't be the first time a mandated 'safety system' has caused an accident (it wouldn't just be Boeing and GE - TCMA was forced by the FAA and EASA to prevent a scenario that had never caused a fatal accident) - and there would be a lot embarrassing questions for all involved. But I personally know many of the people who created, validated, and certified the GEnx-1B TCMA logic - and can't imagine what they would be going through if they missed something (coincidentally, one of them was at my birthday party last weekend and inevitably we ended up talking about what we used to do at Boeing (he's also retired)). Worse, similar TCMA logic is on the GEnx-2B (747-8) - which I was personally responsible for certifying - as well as the GE90-115B and the 737 MAX Leap engine - the consequences of that logic causing this accident would be massive.

67 users liked this post.

Locking Nut
2025-06-14T20:59:00
permalink
Post: 11901828
Originally Posted by smith
Just remembered this video of a787 with its RAT deployed. You can certainly hear it. A lot of people said you could hear it in the AI video but I couldn\x92t.
Originally Posted by MyTH
RAT? Here\x92s an unprocessed frame from the video. I really don\x92t see that the RAT has deployed.
The point you think you are making here has recurred throughout the thread. To try and put it to rest:

Here\x92s an unprocessed frame from the video
The first omission/error here is in describing a definite article (i.e. the video), alongside claiming that the pic you posted is 'unprocessed". It might not be processed, it just isn't very good quality. Which you might not realise if you haven't seen the original, higher resolution version of the clip.

The are now numerous social media sources for copies of the flyby/crash smartphone video. Many of them are actually a repost (or possibly multiple independently made iterations) of a second generation recording - made via a smartphone filming the original video playing on a monitor and via the monitor's (likely very poor) speakers. This version has been incorrectly assumed to be (and described as derived from) "CCTV" in some posts. The "screen recorded" nature of this particular version of the video is obvious from the camera movement (including showing the bezel and edge of the screen it is filming), moire patterns etc. The original (or rather, what *appears* to be a first generation, but compressed, copy of the original) version of the video has *also* been posted on social media (and thereafter, here) with both then being dissemanated across multiple social media accounts and at varying video resolution and compression ratios.

There are further posts of the "screen recorded" copy of the video in which AI enhancement and other filters have been used to try and "improve" the video quality. Anyone even attempting to filter the video in that way doesn't understand the way such filters operate (i.e. they are trying to make the picture "more watchable" rather than sharpen it/make it more *accurate*), and anyone trying to draw conclusions from such "enhanced" versions needs to think carefully about what they are looking at.

The framegrab you have posted above is clearly from the "screen recorded" video. The original version (with its attendant much higher video *and* audio quality) *does* appear to show an object beneath the airframe where the RAT hub would be - and also - albeit only for a handful of frames - appears to show the motion blurred impeller disc. The fact that this artifact is only visible for a few frames is explicable via the heavily compressed digital video but it is consistent.

The "full" video itself is also longer than the "screen recorded" version and starts earlier in the incident timeline. And a distinctive propeller-type beat *is* audible, both before *and* after the aircraft comes into frame, at near identical pitch to the various examples we've seen of a 787 passing a camera with the turbine deployed. One would imagine that the first generation copy of the video as it exists on the device that recorded it is noticeably better quality than *any* of the downsampled/overcompressed social media versions we have seen. And one also sincerely hopes that the Indian AAIB are already in possession of it.

The prevalence of smartphones and social media means this sort of footage is more immediately accessible and more easily dissemanated than at any time in the past. However, anyone trying to draw solid conclusions from a clip posted on social media - especiallly with limited quality, and even more, "enhancement", needs to remember the limitations of what they're seeing.

(Not a pilot, but a former aero electronics engineer with significant subsequent digital forensic experience)

13 users liked this post.

FullWings
2025-06-14T21:17:00
permalink
Post: 11901843
Originally Posted by LTC8K6
IIRC, you would get a warning if you try to retract the flaps too early in the 787.

The gear and flap controls are not easily confused in the 787. They look nothing alike and are not near each other.
Agreed. Also, given an almost 100% likelihood that the RAT deployed pretty early on and the ramifications of this, flaps and gear have almost lost relevance as they wouldn\x92t be able to be moved much after that point during the brief airborne period, even if commanded?

1 user liked this post.

WITCHWAY550
2025-06-14T21:22:00
permalink
Post: 11901851
That\x92s not a false conclusion if in fact hydraulics were lost. I dont think that was the case and if it was engine driven hydraulic pumps have normal output all the way down to idle and actually further. I dont think the RAT deployed for any reason and i am not sure that has been confirmed.
DaveReidUK
2025-06-14T21:27:00
permalink
Post: 11901855
Originally Posted by tdracer
Another hour spent sifting through the stuff since last night (my sympathies to the mods ). A few more comments:

"Real time engine monitoring" is typically not 'real time' - it's recorded and sent in periodic bursts. Very unlikely anything was sent from the event aircraft on this flight.

Commanded engine cutoff - the aisle stand fuel switch sends electrical signals to the spar valve and the "High Pressure Shutoff Valve" (HPSOV) in the Fuel Metering Unit, commanding them to open/close using aircraft power. The HPSOV is solenoid controlled, and near instantaneous. The solenoid is of a 'locking' type that needs to be powered both ways (for obvious reasons, you wouldn't want a loss of electrical power to shut down the engine). The fire handle does the same thing, via different electrical paths (i.e. separate wiring).

As I've noted previously, a complete loss of aircraft electrical power would not cause the engines to flameout (or even lose meaningful thrust) during takeoff. In the takeoff altitude envelope, 'suction feed' (I think Airbus calls it 'gravity feed') is more than sufficient to supply the engine driven fuel pumps. It's only when you get up to ~20k ft. that suction feed can become an issue - and this event happened near sea level.

Not matter what's happening on the aircraft side - pushing the thrust levers to the forward stop will give you (at least) rated takeoff power since the only thing required from the aircraft is fuel and thrust lever position (and the thrust lever position resolver is powered by the FADEC).

The TCMA logic is designed and scrubbed so as to be quite robust - flight test data of the engine response to throttle slams is reviewed to insure there is adequate margin between the TCMA limits and the actual engine responses to prevent improper TCMA activation. Again, never say never, but a whole lot would have had to go wrong in the TCMA logic for it to have activated on this flight.

Now, if I assume the speculation that the RAT deployed is correct, I keep coming up with two potential scenarios that could explain what's known regarding this accident:
1) TCMA activation shutdown the engines
or
2) The fuel cutoff switches were activated.
I literally can come up with no other plausible scenarios.

In all due respect to all the pilots on this forum, I really hope it wasn't TCMA. It wouldn't be the first time a mandated 'safety system' has caused an accident (it wouldn't just be Boeing and GE - TCMA was forced by the FAA and EASA to prevent a scenario that had never caused a fatal accident) - and there would be a lot embarrassing questions for all involved. But I personally know many of the people who created, validated, and certified the GEnx-1B TCMA logic - and can't imagine what they would be going through if they missed something (coincidentally, one of them was at my birthday party last weekend and inevitably we ended up talking about what we used to do at Boeing (he's also retired)). Worse, similar TCMA logic is on the GEnx-2B (747-8) - which I was personally responsible for certifying - as well as the GE90-115B and the 737 MAX Leap engine - the consequences of that logic causing this accident would be massive.
A TCMA bug just doesn't bear thinking about, I really hope that doesn't turn out to be the case.

5 users liked this post.

Compton3fox
2025-06-14T21:57:00
permalink
Post: 11901873
Originally Posted by LTC8K6
IIRC, you would get a warning if you try to retract the flaps too early in the 787.

The gear and flap controls are not easily confused in the 787. They look nothing alike and are not near each other.
Not to mention the fact the flaps were selected when you view pictures from the accident site. Dare I mention the RAT being deployed too? That does not happed if you select flaps up at the wrong time.
Compton3fox
2025-06-14T22:01:00
permalink
Post: 11901878
Originally Posted by WITCHWAY550
That\x92s not a false conclusion if in fact hydraulics were lost. I dont think that was the case and if it was engine driven hydraulic pumps have normal output all the way down to idle and actually further. I dont think the RAT deployed for any reason and i am not sure that has been confirmed.
Read the thread about the audio analysis. Its pretty conclusive. The RAT was almost certainly deployed. Plane crash near Ahmedabad..

1 user liked this post.

mec31
2025-06-14T22:05:00
permalink
Post: 11901882
RAT (???)

Originally Posted by neila83
We haven't thought about it because it didn't happen. We have a video of the plane with no engine sound and the RAT clearly audible. The RAT is also visible in the video. The pilot sent a mayday mentioning loss of power. The only survivor says the cabin went dark and lights were flickering. It's pretty compelling no?

Why are people still talking about flaps and incorrect takeoff data settings?
Like many (most?) here, I really don't have a theory/guess that I would call 'high confidence'. Among those who do, many of them seem to rely in part on RAT deployment. I can't say whether it was or not. I do not believe any of the available pictures and video confidently attest to the situation from a visual standpoint. Regarding 'RAT clearly audible' I would say that we do not know that either. That audio is taken from camera phone video. It seems entirely possible to me that the sound in question could very well be a scooter, or some other ground vehicle that is much closer to the camera than the plane is. So anyone who is confident of RAT deployment has to be equally confident that the sound we hear (I agree there is a sound) could not possibly be anything other than a RAT. That seems a bit of a heavy lift to me. Any number of audio sources not visually captured on the video could have produced that sound. I am certainly not intimately acquainted with the sound of every tuktuk, scooter, piece of construction equipment, etc. that are common on the ground in Ahmadabad. We'll know soon enough but the evidence we have only weakly suggests a deployed RAT.
appruser
2025-06-14T22:11:00
permalink
Post: 11901887
Originally Posted by Sev68
How could he know that they revved up if the engines were shut down, what noise could make him think so?
Have been thinking about this a bit in this thread. First I thought it might be the APU spooling up, but apparently the APU isn't very audible in seat 11A - good 787 sound insulation. Cabin Air Compressors are not started either if power loss induces APU start, so that might not be it either. Since his sequence doesn't give a good idea of when, is the RAT a potential source of this noise? would it be audible in the cabin? Apparently the RAT is variable pitch constant speed, so as the aircraft speed decayed from 170kt to 120kt, would it become louder as the RAT prop pitch adjusted to the lower airspeed?

It's a great question!
BrogulT
2025-06-14T22:17:00
permalink
Post: 11901893
Originally Posted by tdracer
Now, if I assume the speculation that the RAT deployed is correct, I keep coming up with two potential scenarios that could explain what's known regarding this accident:
1) TCMA activation shutdown the engines
or
2) The fuel cutoff switches were activated.
I literally can come up with no other plausible scenarios
Thank you for your qualified input! I had asked a question about the ability of the engines to suction fuel if the fuel pumps were inop. Specifically, I wanted to know whether that is ever tested and if so how often and by who. IOW, if due to wear, a maintenance mistake or whatever, if the engines were in fact NOT able to suction fuel, since the SOP is to run all of the pumps would that problem ever be noticed in normal operations? If not, then if both engines had that problem (imagine a faulty maintenance procedure that somehow caused this to happen to a lot of engines) then a sudden, complete collapse of the electrical system would cause the pumps to stop--and thus the engines. If any of that is even a possiblity then all of the other AI 787s should be checked.
FullWings
2025-06-14T22:21:00
permalink
Post: 11901900
I think it needs to be said again that pretty much anything can happen to the aircraft systems and the engines will carry on running - this is by design as they have independent FADEC and power supplies and at sea level fuel will get through without boost pumps. You could almost saw the wing off the fuselage and the engine would still produce thrust, TCMA notwithstanding.

We don\x92t know yet what actually triggered the RAT from the relatively short list but every item on it means there is a serious/critical failure(s). The flight path suggests that it was a double engine failure or shutdown (commanded or uncommanded) as anything else should have left the aeroplane in a poor state but able to climb away.

6 users liked this post.

framer
2025-06-14T22:34:00
permalink
Post: 11901910
Now, if I assume the speculation that the RAT deployed is correct, I keep coming up with two potential scenarios that could explain what's known regarding this accident:
1) TCMA activation shutdown the engines
or
2) The fuel cutoff switches were activated.
I literally can come up with no other plausible scenarios.
I\x92d like to give you another option to consider in what must be a worrying time;
Am I right in saying, from a mathmatical perspective, that dual engine flame out due biocide overdose would be more likely than a TCMA activation shutting down the engines? Considering we have examples of engines reducing to idle within seconds of each other in the past, but we have no examples of airborne TCMA issues I would have thought this to be the case. Likewise, nefarious intent also appears more likely statistically than a TCMA issue.
I have high-school level statistics under my belt so I pose that as a question for people much smarter than myself.
LTC8K6
2025-06-14T22:56:00
permalink
Post: 11901928
Originally Posted by BugBear
There was banging prior the failed generator in the 787 Emergency landing....plus loss of altitude, direction, and EE Does all elec load go to the opposite engine? Because if it does and that engine either fails or gets shut down mistakenly ....OOPS no Thrust, no Electrical power, only instruments from APU. If the APU started on climb, we know exactly what occurred....
Does the RAT make a banging noise on deployment?