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| Sailvi767
July 18, 2025, 02:32:00 GMT permalink Post: 11924794 |
Apologies for the delay in responding to your posts. I see that you and others have stepped in, thanks.
I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself." 08:08:46.55 ... 575ft ... 21ft ... 184kt 08:08:48.14 ... 600ft ... 46ft ... 179kt 08:08:48.61 ... 600ft ... 46ft ... 177kt 08:08:49.01 ... 600ft ... 46ft ... 177kt 08:08:49.46 ... 625ft ... 71ft ... 177kt 08:08:49.92 ... 625ft ... 71ft ... 174kt 08:08:50.39 ... 625ft ... 71ft ... 174kt 08:08:50.87 ... 625ft ... 71ft ... 172kt From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that. What's interesting is that the ADSB data covers: - 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment) - 50ft of altitude gain - Declining airspeed from the 1st reading to the last in this final segment from the runway. Big questions in my mind: 1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds? 2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd. 3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF. It's just weird . The widely watched video shows a very normal initial rotation and climb. Subjects
ADSB
FlightRadar24
Fuel (All)
Fuel Cutoff Switches
Hydraulic Failure (All)
Parameters
RAT (All)
RAT (Deployment)
RUN/CUTOFF
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| appruser
July 18, 2025, 04:43:00 GMT permalink Post: 11924815 |
I am not sure why 50 feet in 4 seconds seems odd right after liftoff in a heavy aircraft. That corresponds to 750 FPM. Seems entirely normal to me. The rate would have been increasing as the timeline advanced. I would also point out that RAT deployment verses the rat coming online fully are two different times. When that RAT is singled to deploy it bangs out nearly instantly. It begins producing its rated electrical and hydraulic power sometime after deployment.
The widely watched video shows a very normal initial rotation and climb. Since the preliminary report states E2 cutoff after 3-4 seconds after lift-off, if that cutoff corresponds to ADSB interruption and which itself was only transmitting for 4 seconds, then 50ft after liftoff is a bit anemic? But if we include the first 25ft after rotation but before lift-off, then, because the ADSB duration is only 4 seconds, it means that ADSB was interrupted before the E2 FCO operation. I don't know if there is a sliding window - part after rotation, part after lift-off that might meet all of these constraints. That still leaves unexplained the declining airspeed seen in the ADSB data... did prior discussions on the ADSB data cover this? is there a good explanation? Last edited by appruser; 18th July 2025 at 05:03 . Reason: fixed heights Subjects
ADSB
Fuel (All)
Fuel Cutoff Switches
Hydraulic Failure (All)
Preliminary Report
RAT (All)
RAT (Deployment)
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| Mrshed
July 18, 2025, 06:07:00 GMT permalink Post: 11924844 |
Apologies for the delay in responding to your posts. I see that you and others have stepped in, thanks.
I think for various reasons the ADSB data's absolute values are offset by some amount, for possibly all of the parameters. But there should be consistency in the deltas for the timestamp (by receiving station), the raw baro altitude, the Flightradar24 AGL values, and the airspeed. Flightradar24 themselves note that for altitude " ... the data is not above ground level, but it is consistent to itself." 08:08:46.55 ... 575ft ... 21ft ... 184kt 08:08:48.14 ... 600ft ... 46ft ... 179kt 08:08:48.61 ... 600ft ... 46ft ... 177kt 08:08:49.01 ... 600ft ... 46ft ... 177kt 08:08:49.46 ... 625ft ... 71ft ... 177kt 08:08:49.92 ... 625ft ... 71ft ... 174kt 08:08:50.39 ... 625ft ... 71ft ... 174kt 08:08:50.87 ... 625ft ... 71ft ... 172kt From the Preliminary Report's airport cctv picture, the RAT was seen deployed at, by my estimate here , 150ft baro altitude, between 4-7 seconds after rotation. So the ADSB readings have to be prior to that. What's interesting is that the ADSB data covers: - 4-5 seconds of time (let's approximate 4 seconds from 46.55 to 50.55, ignoring the 0.32s for the moment) - 50ft of altitude gain - Declining airspeed from the 1st reading to the last in this final segment from the runway. Big questions in my mind: 1. If the loss of ADSB corresponds to the E1/E2Fuel Cutoff switches being moved from RUN -> CUTOFF, why is the airspeed declining for the prior 4 seconds? 2. In 4 seconds, why is there only 50ft of altitude gain? that seems odd. 3. To account for only 50ft of alt gain, if we assume the 1st reading is on the runway just before rotation, the intermediate +25ft alt gain is at rotation (Nose up but MLG still on the runway), and the last 4 readings are in the air (nose up an additional 25ft), that means that 1 second or less after lift-off, ADSB was lost - this is before E1/E2 FCO RUN-> CUTOFF. It's just weird . Subjects
ADSB
FlightRadar24
Fuel (All)
Fuel Cutoff Switches
Parameters
RAT (All)
RAT (Deployment)
RUN/CUTOFF
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| Pilot DAR
December 23, 2025, 22:27:00 GMT permalink Post: 12010158 |
Let's recall what the AI-171 preliminary accident report said:
.....the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec.
Subjects
AI171
Fuel (All)
Fuel Cutoff
Fuel Cutoff Switches
RAT (All)
RAT (Deployment)
RUN/CUTOFF
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| AAKEE
December 24, 2025, 10:07:00 GMT permalink Post: 12010314 |
Let's recall what the AI-171 preliminary accident report said:
That's caused by a person's hand, not a bit flip affecting a circuit board. Other automated actions (RAT deployment) after that seemed to operate as intended. Sure, bit flips are a thing, but not this thing... Subjects
AI171
RAT (All)
RAT (Deployment)
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| Leonakua
December 24, 2025, 17:48:00 GMT permalink Post: 12010481 |
Correction... The report was "switches
t
ransitioned to CutOff". Given the Ambiguous nature of the prelim in general, the team may have meant "valves transitioned to cut off". Which is what happened. I wouldn't bother with this, but what is posted tends to become gospel. I think the report is sloppy, and quite possibly purposefully so. So basing a discussion on it is a waste of time. 2\xa2
Yeah, just give me a 01 second.... Oh yeah, "Why did you Cut Off?" ( Fuel not mentioned ) And, wasn't RAT deployed prior to "transition" ? Last edited by Leonakua; 24th December 2025 at 18:00 . Subjects
Fuel (All)
Fuel Cutoff Switches
Pilot "Why did you cut off"
RAT (All)
RAT (Deployment)
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| tdracer
December 24, 2025, 19:19:00 GMT permalink Post: 12010502 |
Correction... The report was "switches
t
ransitioned to CutOff". Given the Ambiguous nature of the prelim in general, the team may have meant "valves transitioned to cut off". Which is what happened. I wouldn't bother with this, but what is posted tends to become gospel. I think the report is sloppy, and quite possibly purposefully so. So basing a discussion on it is a waste of time. 2\xa2
Yeah, just give me a 01 second.... Oh yeah, "Why did you Cut Off?" ( Fuel not mentioned ) And, wasn't RAT deployed prior to "transition" ? When you need invent stuff (or new meanings) for your hypothesis to work, it's time come up with a new hypothesis... Last edited by tdracer; 24th December 2025 at 19:41 . Subjects
Fuel (All)
Fuel Cutoff Switches
Pilot "Why did you cut off"
Preliminary Report
RAT (All)
RAT (Deployment)
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| Musician
December 24, 2025, 19:38:00 GMT permalink Post: 12010507 |
The RAT was deployed after the switches transitioned.
This is because RAT deployment is automatic when both engines are shut down. See https://paulross.github.io/pprune-th...oyment-10.html Subjects
RAT (All)
RAT (Deployment)
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| Musician
January 24, 2026, 09:01:00 GMT permalink Post: 12026247 |
Very interesting article in the Daily Telegraph.
The over riding impression I get is one of vested interests protecting their own position rather than following the evidence. https://apple.news/AHSrBmul0Tv-yToeImigXTA There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:
Just 15 minutes before take-off, the aircraft\x92s bus power control units (BPCUs), which manage the electrical systems, sent real-time signals to Boeing and Air India indicating malfunctions with both BPCUs.
In isolation, none of these problems is classed as major issues, but taken together, according to some experts they show a pattern of electrical problems that point to issues with the core network.
According to reports in India, in the minute before the aircraft took off, and almost certainly as it was heading down the runway, the 787\x92s aircraft communications addressing and reporting system sent a fault code to Boeing and Air India which indicated that the Fadec was receiving corrupted data from an engine monitoring probe.
Pierson says: \x93That aircraft was sending out fault messages before it took off. That is a big red flag. The aircraft health management system was also sending real-time data to Air India and Boeing so they had that information before the fires were even put out. None of that information was included in the preliminary report.
Last edited by Musician; 24th January 2026 at 11:14 . Subjects
FDR
Preliminary Report
RAT (All)
RAT (Deployment)
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| Ver5pen
January 24, 2026, 18:30:00 GMT permalink Post: 12026533 |
Non-paywalled version:
https://www.aol.com/articles/sabotag...060100148.html
There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:
Just 15 minutes before take-off, the aircraft\x92s bus power control units (BPCUs), which manage the electrical systems, sent real-time signals to Boeing and Air India indicating malfunctions with both BPCUs.
In isolation, none of these problems is classed as major issues, but taken together, according to some experts they show a pattern of electrical problems that point to issues with the core network.
According to reports in India, in the minute before the aircraft took off, and almost certainly as it was heading down the runway, the 787\x92s aircraft communications addressing and reporting system sent a fault code to Boeing and Air India which indicated that the Fadec was receiving corrupted data from an engine monitoring probe.
Pierson says: \x93That aircraft was sending out fault messages before it took off. That is a big red flag. The aircraft health management system was also sending real-time data to Air India and Boeing so they had that information before the fires were even put out. None of that information was included in the preliminary report.
I still don\x92t believe we have got a clear answer on the recording interval of the engine cutoff switch channel, if it\x92s 1s then the \x91debunking\x92 by saying it can be done very quickly is moot as (near) instant would record as 1s I believe and the RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs were recorded as moved is obviously hugely consequential it\x92s easy to dismiss these narratives as vested interests but let\x92s be honest everyone has a vested interest here and blaming the pilots has been the go to when in doubt for a very very long time- probably as long as aviation has existed in the absence of explicit evidence (does the CVR have more to tell?) of deliberate action or pre-planning this is a horrifically complicated investigation as there will always be plausible deniability on all sides and different courts/judges will rule on it very differently based on their own biases and views Subjects
CVR
FDR
Fuel (All)
Fuel Cutoff Switches
Preliminary Report
RAT (All)
RAT (Deployment)
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| AAKEE
January 24, 2026, 19:54:00 GMT permalink Post: 12026552 |
RAT deployment
RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs
The ones trying to state otherwise either try very hard to make a case with *another* agenda behind or just lacks the knowledge to use the available data correctly. There is not even a slightest doubt that this matches the described sequence and for example the pictures in the report. Subjects
Hydraulic Failure (All)
RAT (All)
RAT (Deployment)
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| FullWings
January 24, 2026, 19:55:00 GMT permalink Post: 12026553 |
What a load of rubbish. Some of it would seem plausible without detailed knowledge of how aircraft systems work but most industry professionals would be able to poke holes in the posited theories, for instance: pinning everything on the fact that the RAT takes exactly 6 seconds to deploy and produce power. I don’t have intimate certification knowledge but I would bet a quid or two on the spec being ‘maximum 6 secs under the most adverse conditions’ and that at the airspeed and density altitude of the accident it might have deployed quicker. Who knows but it’s not something to hang your hat on and it makes every further assumption down the chain invalid. Engineers understand tolerances, hacks don’t.
Edit: Ninja’d by AAKEE but the point stands. Subjects
RAT (All)
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| Someone Somewhere
January 24, 2026, 20:21:00 GMT permalink Post: 12026564 |
Non-paywalled version:
https://www.aol.com/articles/sabotag...060100148.html
There's the old "the RAT deployed early" (assuming it always takes a full 6 seconds to spool up), the water leak, the "can't move both switches in a second", and new "the aft FDR looks like it burned before the crash". And this, which is as yet unsubstantiated, and is likely not relevant at all:
whilst intentional action is the most obvious explanation one can’t ignore data and technical grounds if one is also going to dismiss counter theories on technical grounds
I still don’t believe we have got a clear answer on the recording interval of the engine cutoff switch channel, if it’s 1s then the ‘debunking’ by saying it can be done very quickly is moot as (near) instant would record as 1s I believe
and the RAT element is obviously very relevant, if RAT deployment is not recorded then one has to infer when it deployed based on when it delivered hydraulic/electric capability. And this will come down to counting seconds, any indication that the RAT may have deployed before the fuel cutoffs were recorded as moved is obviously hugely consequential
The engines ran down after the switches were recorded moving. Even if the RAT deployed, that does not suggest that the crew switched the engines off because of an engine failure. No crew is going to shut down the engines down simply because a RAT deploys unexpectedly.
it’s easy to dismiss these narratives as vested interests but let’s be honest everyone has a vested interest here and blaming the pilots has been the go to when in doubt for a very very long time- probably as long as aviation has existed
in the absence of explicit evidence (does the CVR have more to tell?) of deliberate action or pre-planning this is a horrifically complicated investigation as there will always be plausible deniability on all sides and different courts/judges will rule on it very differently based on their own biases and views I don't think you can or will effectively prove whether it was intentional or some kind of an action slip, and by which pilot. I think the accident report will be able to very clearly and with no reasonable doubt show that the switches were physically moved. From the article:
The alternative is
too awful for them to contemplate
: that one of the pilots murdered hundreds of people as collateral damage in a suicide.
Because the aft flight recorder was destroyed, investigators cannot retrieve the one piece of information that it alone contained – the moment it stopped working, which might have provided a vital clue about a fire or electrical failure in the moments before the crash.
The aft EAFR was substantially damaged and could not be downloaded
through conventional means.
The CPM was opened to inspect the memory card. The damage was extensive.
Last edited by Someone Somewhere; 24th January 2026 at 20:32 . Subjects
APU
Action slip
CVR
DFDR
EAFR
Electrical Failure
Engine Failure (All)
FDR
Fuel (All)
Fuel Cutoff Switches
NTSB
Preliminary Report
RAT (All)
RAT (Deployment)
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| scard08
January 25, 2026, 02:54:00 GMT permalink Post: 12026713 |
Subjects
RAT (All)
RAT (Deployment)
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| nikplane
February 01, 2026, 19:49:00 GMT permalink Post: 12030813 |
Technical aspects
Hello everyone.
There's this rumor and/or question going around: Someone was promoting the idea that a diode failure in the backup battery had disabled the battery and both buses. He claimed that the FDR inputs from the switch sensors were coming from opto-isolators, and since they had lost power, they showed the switches going into the open state until power returned from the RAT. For this theory to be valid, a single diode failure would have had to disable the entire aircraft. Please, - just comments on technical aspects? - It's unclear this refers to the forward EAFR backup battery or the Hot Battery Bus (Hot BB). Thanks Last edited by nikplane; 1st February 2026 at 20:04 . Subjects
EAFR
FDR
RAT (All)
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| Pilot DAR
February 01, 2026, 20:09:00 GMT permalink Post: 12030820 |
There's this rumor and/or question going around:
and since they had lost power, they showed the switches going into the open state until power returned from the RAT.
Subjects
RAT (All)
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| Someone Somewhere
February 01, 2026, 20:55:00 GMT permalink Post: 12030826 |
The switches IIRC have both 'run' and 'cutoff' contacts monitored. So if the switches are moved to cutoff, the 'run' contacts open, and the 'cutoff' contacts close.
If
(big if), instead, loss of power resulted in switches appearing open, you would see both 'run' contacts and 'cutoff' contacts as open, which would be a fault.
With no power, the RDCs reading those switch contacts would of course also be unpowered, so you would expect to simply get no data. If the switches appeared to close when the RAT came online, then how would you explain:
It's a nonsense theory with ChatGPT written all over it. It's been discussed at some length previously. Subjects
Fuel (All)
Fuel Cutoff Switches
RAT (All)
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| MechEngr
February 01, 2026, 22:10:00 GMT permalink Post: 12030848 |
Hello everyone.
There's this rumor and/or question going around: Someone was promoting the idea that a diode failure in the backup battery had disabled the battery and both buses. He claimed that the FDR inputs from the switch sensors were coming from opto-isolators, and since they had lost power, they showed the switches going into the open state until power returned from the RAT. For this theory to be valid, a single diode failure would have had to disable the entire aircraft. Please, - just comments on technical aspects? - It's unclear this refers to the forward EAFR backup battery or the Hot Battery Bus (Hot BB). Thanks Subjects
EAFR
FDR
RAT (All)
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| Musician
February 01, 2026, 22:18:00 GMT permalink Post: 12030849 |
Hello everyone.
There's this rumor and/or question going around: Someone was promoting the idea that a diode failure in the backup battery had disabled the battery and both buses. He claimed that the FDR inputs from the switch sensors were coming from opto-isolators, and since they had lost power, they showed the switches going into the open state until power returned from the RAT. For this theory to be valid, a single diode failure would have had to disable the entire aircraft. Please, - just comments on technical aspects? - It's unclear this refers to the forward EAFR backup battery or the Hot Battery Bus (Hot BB). Thanks Notwithstanding the fact that this failure mode is also technically implausible/impossible. Here's a 787 that landed with the battery on fire: https://skybrary.aero/accidents-and-...and-japan-2013
On 16 January 2013, a Boeing 787-8 (JA804A) being operated by All Nippon Airways (ANA) on a scheduled passenger flight from Yamaguchi-Ube to Tokyo Haneda in day Visual Meteorological Conditions (VMC) made an emergency diversion to Takamatsu after a main battery failure was annunciated climbing through FL320.
.
The original perpetrator of this idea is Jeremy John Thompson, with a Youtube video titled "How Air India AI171 B787 crashed - Lithium Battery Diode Module Failure" positing that the battery diode module failed, the battery overcharged and short-circuited, and disaster ensued. This was half a year ago. Last edited by Musician; 1st February 2026 at 22:41 . Subjects
AI171
EAFR
FDR
Fuel (All)
Fuel Cutoff Switches
RAT (All)
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| paulross
February 02, 2026, 12:21:00 GMT permalink Post: 12031064 |
Hello everyone.
There's this rumor and/or question going around: Someone was promoting the idea that a diode failure in the backup battery had disabled the battery and both buses. He claimed that the FDR inputs from the switch sensors were coming from opto-isolators, and since they had lost power, they showed the switches going into the open state until power returned from the RAT. For this theory to be valid, a single diode failure would have had to disable the entire aircraft. Please, - just comments on technical aspects? - It's unclear this refers to the forward EAFR backup battery or the Hot Battery Bus (Hot BB). Thanks Subjects
EAFR
FDR
Preliminary Report
RAT (All)
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