Posts by user "appruser" [Posts: 18 Total up-votes: 29 Pages: 1]

appruser
2025-06-13T17:43:00
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Post: 11900730
Originally Posted by DogTailRed2
If you rotated and then lost all power wouldn't you put the nose down?
Yes, this is the odd part - from the videos it didn't look like there was any attempt to put the nose down for best glide, and even the pitch up (if presumably from fear) was not very pronounced. It basically came down in the same attitude as during the takeoff. That has me wondering if they even had any controls at all. Very low probability, true, but then both engines out is also a low probability event. 'RAT Push and hold 1 second' seems to be a dual-engine fail memory item on a 787, so both engines out would explain the loss of thrust and the RAT deployment.

The lack of obvious debris/smoke during takeoff might indicate it was something other than a birdstrike, and combined with the loss of adsb (per FR24) right over the runway threshold at 70ft agl, maybe it is indicative of something else causing the simultaneous loss of thrust.

Subjects: FlightRadar24  RAT (All)  RAT (Deployment)

appruser
2025-06-13T18:28:00
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Post: 11900785
Originally Posted by Sailvi767
Why would you lower the nose and violently slam the aircraft into ground. The crew flew the aircraft exactly like you should in that situation. They traded angle of attack for descent rate and put the aircraft on the ground with the best chance of survival. Unfortunately with at least 110,000 lbs of fuel and buildings on the decent path the outcome was never going to be good. Doing so also bought them time to try and resolve the engine malfunction.
Nose down would be to get best glide - longest time in the air and max distance. Raising the nose up leads to a stall and brings the aircraft down faster than best glide. It's counter-intuitive, hence the tendency to pull the nose up in a stall or loss of power has to be trained out of pilots.

Subjects: None

appruser
2025-06-13T19:02:00
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Post: 11900816
Originally Posted by Raffael with FF
Although the gear bogie isn\x92t in the initial post-liftoff position, if you can see the retraction mechanism operating in a 787 It first tilts the bogie forward. I\x92d therefore consider that a \x93gear up\x94 switch was activated but the action failed \x97most likely due to hydraulic pressure loss. In the second video (left-side view), I could interpret that gear retraction begins around 24 s and then halts before 27 s, exactly when the aircraft stops climbing.

Just my two cents, from the perspective of an aircraft engineer with a background primarily in Airbus.​​
Thank you, and to HI288 too! this combined with the FR24 blog post about adsb loss just over the runway threshold, and the latest DGCA ask for Air India 787 maintenance adds more weight to the theory, IMO, that there was a major technical issue in play here.

Subjects: DGCA  FlightRadar24  Gear Retraction  Hydraulic Failure (All)  Hydraulic Pumps

appruser
2025-06-13T19:20:00
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Post: 11900831
Originally Posted by AerocatS2A
Firstly, I don\x92t think an inadvertent selection of flaps up caused this accident. I think it\x92s a red herring that seemed plausible initially but it is not consistent with the RAT being deployed, and the evidence for the RAT is strong.

To answer your broader question though, how could such an error happen? It happens because us simple humans learn how to do actions to the point where we don\x92t have to think about them anymore. This allows us to effectively automate routine tasks and save our brains for more novel tasks. The problem arises when we trigger the wrong automatic action in response to a cue. You ask for gear up, I know I need to select the gear up, I know where the gear handle is and what it looks and feels like, yet something goes wrong in the wiring of my body and instead, the flap-up automatic action is run. It\x92s run before I have consciously thought about it.

Sound far fetched? Well it has happened numerous times. I\x92ve seen someone do exactly that, select the flap instead of the gear, and there are incident reports publicly available. All modern passenger jets have a similar layout of the flap lever and the gear lever with the gear looking like a wheel and the flap looking like a wing, yet this error can still happen.

Have you ever gone to put something in the fridge that should\x92ve been put in the cupboard? I\x92d bet that most people have made that weird error at some point in their lives, and yet the fridge doesn\x92t look like the cupboard and they\x92re nowhere near each other.
Neurotypically an error in an automatic action will occur when the routine that encompasses that action is changed. Hence babies being left in back seats of cars, and probably a factor for the sterile flight deck rule. Any reason to think that might have been in play here?

Subjects: Flap Retraction  Flaps (All)  Gear Retraction  RAT (All)  RAT (Deployment)

appruser
2025-06-13T23:21:00
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Post: 11900993
Combining all the bits and pieces of info from this thread so far, IMO we can theoretically sequence it thus using the video from the left:

00:18 Rotation. Normal takeoff config.
00:24 Gear up starts. per Raffael with FF.
......... FR24 ADSB last transmission (71ft, 172kt) just before runway threshold. Matches with video aircraft altitude at 1/2 wingspan.
......... ? Full power flameout leaves N2 ~ 60%; Airspeed < 200k so N2 will decay to 15% in 8-10s?
......... ? Takeoff EGT of 900C needs 25-35s to fall below 250C ?
00:27 Gear up stops. per Raffael with FF. Bogies tilted.
......... ? APU starts. 20-55s to 95%N?
......... Per 787 dual-engine fail/stall memory items, PM initiates Fuel Cutoff and Run.
00:28 Visible loss of thrust. Alt ~ 200ft using aircraft wingspan as measure.
......... Matches with eyewitness "within 5-10s ... it was stuck in the air".
......... Per 787 dual-engine fail/stall memory items, PM initiates RAT Switch for 1s. Whether auto or manual, the RAT initiates.
......... RAT "bang" heard by survivor
......... RAT coming online accounts for eyewitness "lights started flickering green and white".
......... Per 787 QRH below 1000ft, PF makes no change to Main Landing Gear and flaps, aircraft pointed straight for best glide.
00:31 Descending visibly, somewhere beyond the runway threshold. Alt ~ 200ft using aircraft wingspan as measure.
......... ? Because EGT > 250C FADEC blocks fuel (T-HOT hot restart inhibit?) so no relight though N2 > 15% ?
......... 787 glide ratio between 16:1 to 25:1 with MLG down, Flaps 5. About 15-20s and 3-5000ft of glide from 200ft?
......... Some flap accounts for the ground pictures.
00:34 ? N2 has presumably decayed to 15%, FADEC flips to X-START: airspeed outside envelope? No hope of relight now.
......... PM/PF transmits Mayday?
......... Video showing RAT deployed.
00:46 APU reaches some fraction of 95%N (APU sound accounting for survivor's perception of thrust?).
00:48 Impact. 4200ft from descent start, 3990ft from airport boundary road. 17s from visible descent start.

if this is a valid sequence, the only remaining question is why the dual-engine failure at ~200ft agl?

with condolences to the families and people affected.

Subjects: ADSB  APU  Condolences  FADEC  Flaps (All)  Flaps vs Gear  FlightRadar24  Fuel (All)  Fuel Cutoff  Gear Retraction  MLG (All)  Mayday  RAT (All)  RAT (Deployment)

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appruser
2025-06-14T00:52:00
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Post: 11901041
Originally Posted by TURIN
Regarding flickering lights.
The 787 has, as far as I know, a unique electrical system. When a light is selected on, either by pressing a button, flicking a switch or a touch screen selection there is no direct link to the lights. All instructions go through computers and are controlled by software.
As a consequence lights are either off or on. A 'dicky' power supply as has been suggested by some will not cause the lights to flicker.
This is not a 737.
As it turns out, the survivor just says that the light came on, green & white. No mention of flickering by him. Looks like a translation issue. Am not allowed to post the url yet; the interview is on X, DDNewslive.

Subjects: None

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appruser
2025-06-14T17:21:00
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Post: 11901674
Originally Posted by Xeptu
LoL have a think about what you just said. Below 200 feet normally in transition to flare, such a rafical body angle change is the very thing that had to be trained out of pilots, it's fatal.
So I called a 787 Captain to ask him about this - in dual-engine fail, at 200ft or below, 170kts, flaps 5, does the PF push the nose down for best glide, do nothing, or push nose up in transition to flare?

This is what he said - the PF *has* to push the nose down to prevent a stall and keep the aircraft flying, and if the PF won't, the aircraft will do so to prevent a stall. How much depends on the flap setting.

Subjects: Flap Setting  Flaps (All)

appruser
2025-06-14T17:41:00
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Post: 11901686
Originally Posted by a3twenty
The survivor mentioned that he felt the pilots are trying to give “race” to the engines but it wasn’t working, Presumably in car terms. The word is used predominantly in India in lieu of revving.
Thank you! the DDNewslive interview is posted on X, and seems to be mistranslated by most of the news agencies - no mention of "thrust" by the survivor, and he doesn't mention flickering lights either, just that a green & white light came on.

I think someone posted a green & white exit sign in the 787 cabin earlier in the thread.


Last edited by appruser; 14th Jun 2025 at 17:49 . Reason: removed speculative bit about APU coming online.

Subjects: None

appruser
2025-06-14T18:11:00
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Post: 11901703
Originally Posted by xetroV
Or he may have heard the RAT spooling up. Valuable as a witness account may be, we\x92ll have to wait for FDR and CVR data and/or wreckage analysis before drawing conclusions.
Good point. In the survivor's narrative, the sequence is: 5-10s after takeoff -> plane seemed stuck in the air -> green & white light came on -> they "gave race for more takeoff" (revved up) -> entered straight into (hostel).

Subjects: CVR  FDR  RAT (All)

appruser
2025-06-14T18:43:00
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Post: 11901720
Originally Posted by Alty7x7
There should not be a max pre-start EGT limit in-flight - that should only occur on the ground for a pilot-initiated Autostart where the starting EGT redlines are lower than for in-flight.

In-flight, the Autorelight function should attempt to restart the engine as soon as a flameout is detected, and for an engine flaming out at high power it might catch it before it even goes sub-idle. Generally, Autorelight will continue attempting until some cutoff N2 at which time it will stop attempting, or if the pilot move the fuel switch to Cutoff. And while the EEC is still powered (via its own PMA) down to roughly 10% N2, the ignition exciters required for Autorelight do get their power from the airplane.
Thank you for the correction.

Could this mean that because there doesn't seem to have been any recovery once descent started, there was no fuel flow to support autorelight? Or that there was fuel flow and autorelight may have succeeded but there wasn't enough thrust generated before impact? From the video total descent time was only 17-20s. I guess what I'm asking is what would be the total cycle time if the first autorelight succeeded: flameout -> autorelight -> useful thrust? And if the PM executed dual-engine fail memory item fuel cutoff to run, how would that change the sequence?

Subjects: Fuel (All)  Fuel Cutoff  Fuel Pumps

appruser
2025-06-14T22:11:00
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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!

Subjects: APU  RAT (All)

appruser
2025-06-15T01:40:00
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Post: 11902038
Originally Posted by nachtmusak
Question: regardless of the intricacies of various aircraft-specific systems, is it possible to establish from sheer aerodynamics what can/cannot have happened here? Or to put it another way - leaving aside any and all rumours, theories, plausible sights/sounds, and other extraneous details, and focusing solely on the flight path, can loss of thrust be conclusively ruled in or out? Several times now I've seen someone put forth the argument that it's impossible for the flight path to have been as short as it is if the flaps were retracted but the engines were still producing (even derated) takeoff thrust. It might be helpful to reach a consensus on whether this is true or not - if it's inconclusive then we're back to where we already are, but if a conclusion can be reached it would probably save everyone a lot of breath going down various theoretical rabbit holes.
IMO

In the CCTV video, the aircraft stops climbing at 00:28. 3 seconds after, it starts visibly descending. At peak altitude, using the 197ft wingspan as a measure, the altitude is around 200ft or below. The fireball is at 00:48, 17s after descent starts visibly.

Per google maps and the impact location mapped at avherald, the impact point is ~3990ft from the airport boundary road and about 4200ft from the midpoint of the runway threshold and the airport boundary road.

16:1 to 25:1 is what I could find for the 787 glide ratio range (unpowered) with main landing gear down and flaps 5. So the aircraft could cover 16 to 25 ft horizontally for every 1 ft of descent.

With a starting altitude of 200ft, that would imply it could have covered 3200ft.to 5000ft during unpowered descent.

The actual distance covered, around 4000ft, certainly seems to suggest that the descent was unpowered.

Subjects: CCTV  Gear Retraction

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appruser
2025-06-16T02:31:00
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Post: 11903067
Originally Posted by LH2000
The passenger specifically mentions the lights flickering green and white, this is a specific observation. Not the flickering which happens in the movies, but that they turned green. Boeing sky interior LEDs can turn green and orange (i call is Jamacan mode) during maintenace and trouble shooting (I was a LAME for 20 years). That points to power glitches and faults with the lights. The generaly public would not know Sky interior LEDs can trun green when they fail.
"Flickering" is a mistranslation that's made its way around the world's news services. He said 'light came on, green & white'.


The translation of 1:43 - 1:56 is: "after, in the plane, light came on, green & white; after, I don't know, to make the plane takeoff more, what do they say, gave it race, something like that; it straight entered at speed, where, what was it'. To which the reporter responds, 'it was a hostel' at 1:57.

Last edited by appruser; 16th Jun 2025 at 03:00 . Reason: removed a word "the" which can be misconstrued; there is no specificity about what light came on in the survivor's account

Subjects: None

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appruser
2025-06-16T06:25:00
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Post: 11903134
Originally Posted by Wannabe Flyer
a slight more precise translation as a native speaker. \x93After take off it felt as if we were still in one place & not moving. Then the sound of the engines racing (common Indian term for revving of engines on bikes & cars with the clutch depressed) & then green & white lights came on in the cabin as we hit something.\x94 In my opinion the race sound he talking about sounds like engine surges if compared to race.
May I make a friendly suggestion - might be best to avoid putting in our own interpretations/perspectives of what he said - for example, he doesn't mention "sound" anywhere - we would interpret 'sound' based on experience, but that isn't quite what he said - he only used the word 'race' (a.k.a 'revved' elsewhere). Another example would be interpreting that he said "we were still in one place & not moving" - what he really said was that it felt like they were "stuck" - his word, nothing about movement or standing still or one place. A third one would be 'green & white lights came on in the cabin as we hit something' makes those two events very close together or simultaneous, when his narrative doesn't actually do that, just that they hit something in the end, and before that they 'gave race', and before that a green & white light came on.

To break down the survivor's narrative into an interpretation, am including below a transliteration, direct translation, and the interpretation.


The survivor is a very fast speaker, so had to slow the video down to 0.5x through X's settings menu on the video to capture everything he said.

Video from 1:32 - 1:56

------------------
Transliteration:
------------------

Takeoff ke baad, ek minute ke andar hee, jab takeoff hua naa, to suddenly paanch das second kaise lagaa jaise stuck ho gaya woh. Baad mein (sirf mere ko???) lagaa kuchch hua, baad mein plane mein light on ho gayee, green aur white. Baad mein woh pata nahin woh plane takeoff jyadaa karne ke liye woh race, (do?) bolte hain kya, race diya waisa kuchch, woh seedha (re?) .. speed mein hee ghus gaya, jahan woh, woh (l??), kya tha woh

1:57
Reporter: woh hostel thaa ek, hospital ka

------------------
As direct a translation as feasible without significant rewording or putting in my own perspective on his wording:
------------------

After takeoff, within one minute, when takeoff happened, then suddenly 5-10 seconds what I felt like it got stuck. After, (only to me???) it felt something happened. After, in the plane, light came on, green & white. After, I don't know, to make the plane takeoff more they race, what do they say, gave race, something like that, it straight (1/2 spoken word 'race'?) in speed got into, where, what, what was it

Reporter: it was a hostel, of the hospital

------------------
Less literal translation, more intepretation:
------------------

After takeoff, within a minute, when takeoff occurred, then suddenly for 5-10 seconds it felt like it was stuck. After, it felt like something happened. After that, in the plane, a light came on, green & white. After, I don't know, to make the plane takeoff more they raced, what do they say - gave it race - something like that; it straight, with speed entered into, what was it -

------------------

Later on he describes the mechanics of his escape, and how he was able to get out through a broken door because there was some space on the outside on the ground floor where he landed, and on the opposite side there was a hostel wall that might have prevented others getting out.

Hopefully this might be somewhat useful, even if to only lay to rest some of the theories based on mistranslations of what he said.

It certainly helped me understand that the timeline here doesn't have enough information to line up his description of in-flight events with what's on the external videos.

For example, using the cctv video for timing, his 5-10s lines up with the takeoff and climb from 00:18 to 00:27, and the "felt like it got stuck" part could correspond to 00:28-00:31 where the aircraft appears to 'stop climbing and float horizontally, very little descent' as compared to after 00:31 when it's visibly descending.

The 'something happened' could be the RAT coming online (bang?) but we don't know because there isn't enough detail. Is the RAT even audible inside the cabin? And then the green & white light could be the ceiling light or the exit sign, we don't know, but there is definitely no flickering mentioned.

The 'giving race' part is mystifying - see earlier discussion in the thread - was it changing pitch in the constant-speed RAT due to declining airspeed, something else, engines spooling up? we just don't have enough info here. When did they 'give race' within that 17s descent from 00:31 to 00:48 impact? If we knew that it might help, but that detail isn't there in his description; not surprising since it was a short descent. I think we have to wait for the data from the recorders, or another external video, or maybe even a video from the cabin if somebody was live-streaming to facebook/instagram/x etc.

Last edited by appruser; 16th Jun 2025 at 07:24 . Reason: readability, added another example of potential error in translation, and question about RAT audibility inside the cabin

Subjects: RAT (All)

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appruser
2025-06-16T06:59:00
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Post: 11903161
Originally Posted by fgrieu
Based on the video taken from the left of the flight path, can we determine at what point of the runway rotation occurred? Is there positive confirmation that the takeoff roll started at the beginning of the runway ? Are the two indicative of trouble before rotation, as the Times states ?

Source: https://www.thetimes.com/world/asia/...rash-vhqw6b7v3 (paywalled)
IMO, I don't know if that is trustworthy - the FR24 ADSB data seems to show that the aircraft was at 21ft AGL between the 1500ft and 2000ft markers from the end of the runway.

https://www.flightradar24.com/blog/f...rom-ahmedabad/

I don't know if I'm allowed to post pictures - my last post with a picture didn't show up, so I'll try adding it separately from this one. It's basically an overlay of the FR24 blogpost map on a google maps satellite view of VAAH.

Subjects: ADSB  FlightRadar24  Takeoff Roll

appruser
2025-06-16T02:31:00
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Post: 11903738
Originally Posted by LH2000
The passenger specifically mentions the lights flickering green and white, this is a specific observation. Not the flickering which happens in the movies, but that they turned green. Boeing sky interior LEDs can turn green and orange (i call is Jamacan mode) during maintenace and trouble shooting (I was a LAME for 20 years). That points to power glitches and faults with the lights. The generaly public would not know Sky interior LEDs can trun green when they fail.
"Flickering" is a mistranslation that's made its way around the world's news services. He said 'light came on, green & white'.


The translation of 1:43 - 1:56 is: "after, in the plane, light came on, green & white; after, I don't know, to make the plane takeoff more, what do they say, gave it race, something like that; it straight entered at speed, where, what was it'. To which the reporter responds, 'it was a hostel' at 1:57.

Subjects: None

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appruser
2025-06-16T06:25:00
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Post: 11903744
Originally Posted by Wannabe Flyer
a slight more precise translation as a native speaker. \x93After take off it felt as if we were still in one place & not moving. Then the sound of the engines racing (common Indian term for revving of engines on bikes & cars with the clutch depressed) & then green & white lights came on in the cabin as we hit something.\x94 In my opinion the race sound he talking about sounds like engine surges if compared to race.
May I make a friendly suggestion - might be best to avoid putting in our own interpretations/perspectives of what he said - for example, he doesn't mention "sound" anywhere - we would interpret 'sound' based on experience, but that isn't quite what he said - he only used the word 'race' (a.k.a 'revved' elsewhere). Another example would be interpreting that he said "we were still in one place & not moving" - what he really said was that it felt like they were "stuck" - his word, nothing about movement or standing still or one place. A third one would be 'green & white lights came on in the cabin as we hit something' makes those two events very close together or simultaneous, when his narrative doesn't actually do that, just that they hit something in the end, and before that they 'gave race', and before that a green & white light came on.

To break down the survivor's narrative into an interpretation, am including below a transliteration, direct translation, and the interpretation.


The survivor is a very fast speaker, so had to slow the video down to 0.5x through X's settings menu on the video to capture everything he said.

Video from 1:32 - 1:56

------------------
Transliteration:
------------------

Takeoff ke baad, ek minute ke andar hee, jab takeoff hua naa, to suddenly paanch das second kaise lagaa jaise stuck ho gaya woh. Baad mein (sirf mere ko???) lagaa kuchch hua, baad mein plane mein light on ho gayee, green aur white. Baad mein woh pata nahin woh plane takeoff jyadaa karne ke liye woh race, (do?) bolte hain kya, race diya waisa kuchch, woh seedha (re?) .. speed mein hee ghus gaya, jahan woh, woh (l??), kya tha woh

1:57
Reporter: woh hostel thaa ek, hospital ka

------------------
As direct a translation as feasible without significant rewording or putting in my own perspective on his wording:
------------------

After takeoff, within one minute, when takeoff happened, then suddenly 5-10 seconds what I felt like it got stuck. After, (only to me???) it felt something happened. After, in the plane, light came on, green & white. After, I don't know, to make the plane takeoff more they race, what do they say, gave race, something like that, it straight (1/2 spoken word 'race'?) in speed got into, where, what, what was it

Reporter: it was a hostel, of the hospital

------------------
Less literal translation, more intepretation:
------------------

After takeoff, within a minute, when takeoff occurred, then suddenly for 5-10 seconds it felt like it was stuck. After, it felt like something happened. After that, in the plane, a light came on, green & white. After, I don't know, to make the plane takeoff more they raced, what do they say - gave it race - something like that; it straight, with speed entered into, what was it -

------------------

Later on he describes the mechanics of his escape, and how he was able to get out through a broken door because there was some space on the outside on the ground floor where he landed, and on the opposite side there was a hostel wall that might have prevented others getting out.

Hopefully this might be somewhat useful, even if to only lay to rest some of the theories based on mistranslations of what he said.

It certainly helped me understand that the timeline here doesn't have enough information to line up his description of in-flight events with what's on the external videos.

For example, using the cctv video for timing, his 5-10s lines up with the takeoff and climb from 00:18 to 00:27, and the "felt like it got stuck" part could correspond to 00:28-00:31 where the aircraft appears to 'stop climbing and float horizontally, very little descent' as compared to after 00:31 when it's visibly descending.

The 'something happened' could be the RAT coming online (bang?) but we don't know because there isn't enough detail. Is the RAT even audible inside the cabin? And then the green & white light could be the ceiling light or the exit sign, we don't know, but there is definitely no flickering mentioned.

The 'giving race' part is mystifying - see earlier discussion in the thread - was it changing pitch in the constant-speed RAT due to declining airspeed, something else, engines spooling up? we just don't have enough info here. When did they 'give race' within that 17s descent from 00:31 to 00:48 impact? If we knew that it might help, but that detail isn't there in his description; not surprising since it was a short descent. I think we have to wait for the data from the recorders, or another external video, or maybe even a video from the cabin if somebody was live-streaming to facebook/instagram/x etc.

Subjects: RAT (All)

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appruser
2025-06-16T23:27:00
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Post: 11903870
Originally Posted by isenguard
Is there any chance he's saying the word 'brace' rather than 'race'?
Reviewed audio again both at normal speed and slowed down, with the potential word 'brace' in mind. He's definitely using the word 'race', in my opinion.

Have a listen - he uses the english word 'race' at 1:48, it isn't a translation:

Additionally, within context of "to make the plane takeoff more, they ____, what do they say - gave it ____ - something like that", the word 'race' is a much better fit than 'brace'. His hand gesture also appears to corroborate the takeoff intent.

Subjects: None

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