June 12, 2025, 10:16:00 GMT
permalink Post: 11898915
The FR24 track is extremely limited
, but it appears to show the aircraft not backtracking to use the full length of runway 23. If correct, it attempted to take off with only 1,800 metres (\xb16,000 feet) of runway.
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FlightRadar24
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June 13, 2025, 00:07:00 GMT
permalink Post: 11899822
Flight Radar 24 has now posted granular data, including the AGL corrected for density altitude: (flightradar24.com/blog/flight-tracking-news/major-incident/air-india-171-crashes-shortly-after-take-off-from-ahmedabad/ - I can't link)
I can't include the photo, but it appears to show the following sequence:
I can't include the photo, but it appears to show the following sequence:
- 08:08:46 - Rotation at around 184 knots near taxiway Charlie
- 08:08:50 - Climb to 71ft AGL near the runway threshold, 172kt
- No further data received after that point
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June 14, 2025, 20:20:00 GMT
permalink Post: 11901748
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
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ADSB
AI171
FlightRadar24
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June 14, 2025, 21:00:00 GMT
permalink Post: 11901782
People really need to stop using FR24 data if they don't understand it.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
Not sure how permanent the content at this URL is, but here's a link to FR24's update which has a CSV with all frames received https://www.flightradar24.com/blog/f...rom-ahmedabad/
Last edited by nachtmusak; 14th June 2025 at 21:04 . Reason: Added a link to the more extensive ADS-B data
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ADSB
AI171
FlightRadar24
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June 14, 2025, 21:07:00 GMT
permalink Post: 11901788
There are more data messages than that, which FR24 shared on the day of the accident and which have been posted a few times in this thread. I'm pretty sure there's also been a comparison of this + previous flights posted in this thread that shows that while the coverage at the airport itself is spotty, it's reasonable to expect further messages to have been received before impact.
Not sure how permanent the content at this URL is, but here's a link to FR24's update which has a CSV with all frames received https://www.flightradar24.com/blog/f...rom-ahmedabad/
Not sure how permanent the content at this URL is, but here's a link to FR24's update which has a CSV with all frames received https://www.flightradar24.com/blog/f...rom-ahmedabad/
Somebody on this forum did some analysis with FR24 data of this flight and other AI171 B787 flights.
See this article for an overview of all scenarios. It all looks very like to an commanded dual engine shutdown. Why nobody knows.
Subjects
AI171
Dual Engine Failure
Engine Failure (All)
Engine Shutdown
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June 14, 2025, 21:08:00 GMT
permalink Post: 11901790
People really need to stop using FR24 data if they don't understand it.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
While those still have the 4\xbd minute gap while the aircraft was presumably backtracking, they resume during the latter part of the takeoff roll where reception is clearly better.
There is little doubt that when they abruptly cease after the aircraft is airborne it's because the plane has stopped transmitting.
Subjects
ADSB
AI171
FlightRadar24
Takeoff Roll
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June 14, 2025, 21:13:00 GMT
permalink Post: 11901794
https://www.flightradar24.com/blog/f...rom-ahmedabad/
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ADSB
FlightRadar24
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June 14, 2025, 21:19:00 GMT
permalink Post: 11901798
People really need to stop using FR24 data if they don't understand it.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.
The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.
The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...
Subjects
ADSB
AI171
FlightRadar24
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June 14, 2025, 21:59:00 GMT
permalink Post: 11901827
Flightradar24 published the CSV with all received data. It had EIGHT datapoints of the aircraft after its rotation showing its altitude.
https://www.flightradar24.com/blog/f...rom-ahmedabad/
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ADSB
FlightRadar24
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June 16, 2025, 07:59:00 GMT
permalink Post: 11903161
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)
Source: https://www.thetimes.com/world/asia/...rash-vhqw6b7v3 (paywalled)
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.
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ADSB
FlightRadar24
Takeoff Roll
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June 17, 2025, 16:00:00 GMT
permalink Post: 11904376
The only thing I would add is the limited ADS-B data I have seen shows the a/c decelerating rapidly from the first data point onwards. It is possible the shutdown occurred when the a/c was on the ground (e.g. after V1). This may seem unlikely given the distance flown, but you can do the maths - a fast a/c has a lot of stored kinetic energy.
Last edited by lighttwin2; 18th June 2025 at 09:51 .
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ADSB
V1
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June 18, 2025, 02:02:00 GMT
permalink Post: 11904814
Originally Posted by
Squawk7700
"The Air India Boeing 787-8 Dreamliner that tragically crashed on June 12, 2025, reached a maximum altitude of approximately 625 feet above sea level—about 425 feet above the airport’s elevation of 200 feet—before it began descending. Other reports indicate the aircraft may have reached up to 825 feet before losing lift."
https://www.flightradar24.com/blog/f...rom-ahmedabad/
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FlightRadar24
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June 18, 2025, 02:33:00 GMT
permalink Post: 11904830
Have a look at the latest data from FR24 (from post 439 in the previous thread).
https://www.flightradar24.com/blog/f...rom-ahmedabad/
https://www.flightradar24.com/blog/f...rom-ahmedabad/
Edit to add - I have made no attempt to correct the raw ADS-B altitude data. There is no need to make any correction to see altitude gain.
Last edited by EXDAC; 18th June 2025 at 02:54 . Reason: revise image to add missing data point
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ADSB
FlightRadar24
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June 18, 2025, 05:34:00 GMT
permalink Post: 11904895
climb rate
FR24 did do that raw ADS-B data comparison. Remember the GPS position and barometric altitude are sent by the aircraft itself. The altitude is sent in 25 ft intervals, so a shallow curve that is smooth in reality looks janky in the data, due to the rounding of the numbers. From https://www.flightradar24.com/blog/f...rom-ahmedabad/ :
We’ve taken data from AI171 departures for the month prior to the accident flight—including two previous operations by VT-ANB—and overlaid their departure paths on the data from AI171 on 12 June. The accident flight is in red, while all other flights are the blue paths. The data shown here is the uncalibrated barometric altitude, so the data is not above ground level, but it is consistent to itself.
Obviously the altitudes are all uncorrected for barometric pressure, which would've varied with the weather on that day; you kind of have to mentally shift the lines vertically downward. Now I looked for, but couldn't find, the post in the old thread where the rotation was triangulated\xb9, but I remember that it was near the turnoff to the high-speed taxiway, so a few seconds ahead of this ADS-B capture. We only have the video to show us what occurred then.
That means the ADS-B data doesn't really tell us whether the first few seconds of the climb were normal or not.
When we compare the red line to the blue lines, the data tells us the climb rate had already decayed significantly before the accident aircraft passed over the end of the runway, because the red flight path is much more shallow than the blue flight paths.
Please correct me if I'm wrong: to my eye, the data alone does not show that the engines must have failed after rotation, because the data does not demonstrate a normal climb rate.
But likewise, the engines can't have failed much before rotation:
This aircraft has got airborne well within the requirements of FAR 25 under which it was certified. It has over 1250m ahead of it passing around 35' based on the video from behind, so the FMC data was not incorrect, the thrust up until after TO was not incorrect, and the CG is not out of range, the time to rotate is within expected range, and the attitude at liftoff is not excessive, the plane is not heavier than expected.
-----
\xb9 I found one of them, anyway. The reference is the CCTV video:
You can triangulate the camera location using the aircraft holding short for takeoff and the road sign. Then draw a line from there just to the right of the instrumentation building and you'll find the aircraft rotated with about 4000 feet of runway remaining (11000+ runway length).
Last edited by Musician; 18th June 2025 at 18:43 . Reason: footnote 1
Subjects
ADSB
AI171
CCTV
Engine Failure (All)
Engine Shutdown
FlightRadar24
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June 18, 2025, 14:57:00 GMT
permalink Post: 11905272
FR24 did do that raw ADS-B data comparison. Remember the GPS position and barometric altitude are sent by the aircraft itself. The altitude is sent in 25 ft intervals, so a shallow curve that is smooth in reality looks janky in the data, due to the rounding of the numbers. From https://www.flightradar24.com/blog/f...rom-ahmedabad/ :
The red line is the accident flight, and it covers approximately 4.3 seconds.
Obviously the altitudes are all uncorrected for barometric pressure, which would've varied with the weather on that day; you kind of have to mentally shift the lines vertically downward.
Wouldn't that only be true if the altimeter setting was the same on all the days those flights were made? Isn't that improbable?
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June 20, 2025, 13:13:00 GMT
permalink Post: 11906909
Flightradar24 and ADS-B
Thank you for your reply! There's a lot we agree on; unfortunately, I'll be cutting that from my response here.
Right. ADS-B is transmitted via radio, so reception can be patchy, or obstructed by someone else transmitting on the same frequency (e.g. other aircraft), so not every datagram that the aircraft sends gets received. When that happens, the live display of FR24 assumes the aircraft kept doing what it did, and when another datagram eventually comes in, it corrects the position. It also connects the locations of these datagrams, regardless of whether the aircraft actually went there. For example, in the AI171 there's a 4-minute gap between a datagram sent on the taxiway, and the next datagram sent when the aircraft was off the ground towards the departure end of the taxiway. FR24 then connected these points via the shortest route; but we know that the aircraft actually used the intervening 4 minutes to taxi to the approach end of the runway, where it then started its take-off run. So that was false. (Another source of errors is when different FR24 receivers don't have synchronised clocks, so a mixture of data from these can have weird artifacts as a result.)
However, the datagrams that FR24 actually received were correct. They contain the GPS position of AI171 and its unadjusted barometric altitude, as determined by its onboard instruments. This data is as reliable as the instruments themselves are. (An example here is that the NTSB wasn't sure that the altimeter on the Blackhawk that crashed at Washington-Reagan was accurate; if that is the case, the ADS-B data would also be affected.)
On their blog post at https://www.flightradar24.com/blog/f...rom-ahmedabad/ , FR24 have published the data that they actually received.
Have you ever seen a parabolic trajectory from "the short end"?
Yes.
Okay, didn't know that, I guess suggests means it's uncertain? Can you tell me from what height to what height it suggests this?
It's uncertain because the 787 rounds all altitudes it sends to the nearest multiple of 25. The altitudes sent were from 575 ft to 625 ft., but that's MSL and not adjusted for the weather: low air pressure makes that number higher than the actual altitude. FR24 adjusted this to 21ft climbing to 71 ft, but it could've been 30 to 60 or maybe 10 to 80, as it's rounded. I think it's fairly close to 50 feet of climb, though.
1) people taking the MSL altitude literally (625 ft)
2) people adjusting for airport elevation (189 ft), but not for pressure: 437 ft
3) people adjusting for pressure, some adjusting for temperature, get 71 to ~100 feet for the last recorded altitude.
But while ADS-B reception was lost then (or the transmitter lost power), the aircraft continued climbing; examine the cctv video, knowing the wingspan is ~200 feet, we see that the aircraft reached 200 feet but not much more.
The survivor likened the sound to a car engine revving up. If you've listened to a good version of the phone video, you'll have noticed the "vroom" sound at the start that some likened to a motorcycle. That sound is the RAT in action, and you can imagine what that would sound like when it rapidly spins up: like a driver stepping on the throttle with their car engine in neutral.
The RAT deploying is a consequence of a dual engine shutdown. It says nothing about whether the TMCA was involved.
[Now I just hope your post is still there as I post this.
]
Sure, actual data is usually more accurate than eyeballed stuff. But not always. In fact, it's often the eye that determines that something measured or calculated is "Off". How accurate is ADS-B data? I've seen FR24 tracks go way off course then suddenly get corrected / interpolated, frequently. The erroneous data seems to be "removed" by their algorithm, but where are the errors arising? Why this inaccuracy, and therefore, how accurate are the datagrams referred to? I know there were no datagrams received during the backtrack that I accept actually occurred, but that's completely different from receiving erroneous ADS-B data.
However, the datagrams that FR24 actually received were correct. They contain the GPS position of AI171 and its unadjusted barometric altitude, as determined by its onboard instruments. This data is as reliable as the instruments themselves are. (An example here is that the NTSB wasn't sure that the altimeter on the Blackhawk that crashed at Washington-Reagan was accurate; if that is the case, the ADS-B data would also be affected.)
On their blog post at https://www.flightradar24.com/blog/f...rom-ahmedabad/ , FR24 have published the data that they actually received.
Sure, the CCTV footage I've seen is very poor, a video, moved about and zoomed, of the CCTV screen. Not easy to judge, but still useful and could be analysed frame-by-frame to compensate for all the extraneous input. Anyway, it's obvious to me that the rate of climb dropped abruptly just before the flight attained its apex, as if thrust was suddenly cut off.
Knowing the momentum to altitude conversion, it might be possible to estimate whether that's true or not. The evident RAT deployment supports engine shutdown, not just engines to Idle, doesn't it? In that case, it would be useful to know at what altitude the engine shutdown took place.
(The ADS-B data suggests the speed diminished 7% for ~50 ft of climb.)
And why all the wrong figures for the height attained, quoted in previous thread? Can't all be the atmospheric conditions.
2) people adjusting for airport elevation (189 ft), but not for pressure: 437 ft
3) people adjusting for pressure, some adjusting for temperature, get 71 to ~100 feet for the last recorded altitude.
But while ADS-B reception was lost then (or the transmitter lost power), the aircraft continued climbing; examine the cctv video, knowing the wingspan is ~200 feet, we see that the aircraft reached 200 feet but not much more.
One fact that alters things substantially is whether the survivor's impression is correct that possibly the engines started to spool up again just before impact.
If that's the case then what does that do to the possibility or otherwise that the TMCA system caused a dual engine shutdown?
[Now I just hope your post is still there as I post this.
]
Last edited by Musician; 20th June 2025 at 13:26 .
Subjects
ADSB
AI171
CCTV
Dual Engine Failure
Engine Failure (All)
Engine Shutdown
FlightRadar24
Fuel (All)
Fuel Cutoff Switches
NTSB
RAT (All)
RAT (Deployment)
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July 12, 2025, 11:43:00 GMT
permalink Post: 11920474
SLF: I have a small observation but I'm not sure what it means or if it has any relevance to the accident.
Previously I had assumed that the ADS-B data cut out at the same time as power was lost, so I imagined that whatever caused the fairly clear loss of thrust would have happened not too long before. But this report throws a bit of a wrench in my understanding of that.
According to the report, the fuel cutoff switches transition from RUN to CUTOFF at or very shortly after 08:08:42 UTC. Both engines' N2 values pass below minimum idle speed and the RAT begins supplying hydraulic power at about 08:08:47. Does this not imply that the generators have already been lost? With the APU also being off (the APU inlet door is noted to start opening at 08:08:54), I would have expected ADS-B data to cut out at or before 08:08:47. But curiously FlightRadar24 at least claims to have received data frames from the aircraft until 08:08:51.640970, almost five seconds later and almost ten seconds after the transition to CUTOFF (though the last frame containing coordinates comes at 08:08:50.871005).
Could anyone with relevant experience confirm how long it would take for AC power to be lost in this situation? Also, is it usual/unusual for a preliminary report like this to mention if/when the flight recorder switched to its independent power supply? I imagine it would definitely be in the final report, but I'd hoped it would be easily observable enough to be in this one.
Beyond idle curiosity I'm asking because the report also says the no. 1 engine's cutoff switch transitioned from CUTOFF to RUN at "about 08:08:52", which oddly coincides with the last ADS-B data frame at 08:08:51.640970, and that seems important somehow. Or more likely I'm just ignorant of some quirk of the 787's electrical system.
For reference FR24's CSV containing all ADS-B frames supposedly received from the aircraft can be found in their post here: https://www.flightradar24.com/blog/f...rom-ahmedabad/
Previously I had assumed that the ADS-B data cut out at the same time as power was lost, so I imagined that whatever caused the fairly clear loss of thrust would have happened not too long before. But this report throws a bit of a wrench in my understanding of that.
According to the report, the fuel cutoff switches transition from RUN to CUTOFF at or very shortly after 08:08:42 UTC. Both engines' N2 values pass below minimum idle speed and the RAT begins supplying hydraulic power at about 08:08:47. Does this not imply that the generators have already been lost? With the APU also being off (the APU inlet door is noted to start opening at 08:08:54), I would have expected ADS-B data to cut out at or before 08:08:47. But curiously FlightRadar24 at least claims to have received data frames from the aircraft until 08:08:51.640970, almost five seconds later and almost ten seconds after the transition to CUTOFF (though the last frame containing coordinates comes at 08:08:50.871005).
Could anyone with relevant experience confirm how long it would take for AC power to be lost in this situation? Also, is it usual/unusual for a preliminary report like this to mention if/when the flight recorder switched to its independent power supply? I imagine it would definitely be in the final report, but I'd hoped it would be easily observable enough to be in this one.
Beyond idle curiosity I'm asking because the report also says the no. 1 engine's cutoff switch transitioned from CUTOFF to RUN at "about 08:08:52", which oddly coincides with the last ADS-B data frame at 08:08:51.640970, and that seems important somehow. Or more likely I'm just ignorant of some quirk of the 787's electrical system.
For reference FR24's CSV containing all ADS-B frames supposedly received from the aircraft can be found in their post here: https://www.flightradar24.com/blog/f...rom-ahmedabad/
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ADSB
APU
DFDR
FlightRadar24
Fuel (All)
Fuel Cutoff
Fuel Cutoff Switches
Generators/Alternators
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Preliminary Report
RAT (All)
RUN/CUTOFF
Timeline (Preliminary Report)
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July 13, 2025, 22:06:00 GMT
permalink Post: 11921654
Thank you for your reply! I'm aware you know more about ADS-B than I do, and I'm happy to learn.
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Beware of comparing the speeds from ADS-B, which are groundspeeds, with those from the report, which are IAS.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
Last edited by Musician; 13th July 2025 at 22:36 .
Subjects
ADSB
APU
CCTV
Preliminary Report
RAT (All)
Timeline (Preliminary Report)
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July 13, 2025, 22:15:00 GMT
permalink Post: 11921667
Thank you for your reply! I'm aware you know more about ADS-B than I do, and I'm happy to learn.
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 808:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 808:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
Subjects
ADSB
APU
CCTV
RAT (All)
Links are to this post in the relevant subject page so that this post can be seen in context.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 14, 2025, 00:43:00 GMT
permalink Post: 11921782
Thank you for your reply! I'm aware you know more about ADS-B than I do, and I'm happy to learn.
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
As you know, I'm referring to the map view and data on https://www.flightradar24.com/blog/f...rom-ahmedabad/ .
That's what I thought at first, based on the time stamps.
08:08:50.87 last full ADS-B message (172 kts)
08:08:54 APU inlet door starts to open, per the report.
My problem here is that the report also says that the maximum speed was 180 knots IAS at about 08:08:42. And we have
2025-06-12T08:08:46.550875Z,8005ec,23.069138,72.625871,575
associated with 184 kts as the first ADS-B message in the sequence.
Given that the clocks of ADS-B receivers are sometimes off, I think this might actually represent the moment of maximum speed; but then the AFS-B clock would be 4 seconds fast.
And that's why I adjusted my times.
A way to cross-check would be to track the aircraft position over time from the point of rotation, or to use the new photo in the report that shows the RAT over the runway to triangulate where that was.
Yes.
Would low pressure and high temperature make IAS lower than ground speed, even with the 7 knot headwind?
Either way, if they were decelerating at approximately 3 knots per second, then they would've ended up at about 150 knots IAS, which is less than Vr.
When I look at the CCTV video, 13 seconds into the flight, the aircraft is just "over the hump" and starts descending, so that tracks.
At this point, I don't know what having the engines spool up instead of being dead weight would've done to that flight path; and how successfully the aircraft could've been recovered from that.
Maybe they had only 4 seconds to flip those switches, instead of 5 seconds?
Still, the best bet is to not ask questions, but flip these switches back ASAP, no?
Subjects
ADSB
APU
CCTV
Engine Failure (All)
Engine Shutdown
Preliminary Report
RAT (All)
Timeline (Preliminary Report)
Links are to this post in the relevant subject page so that this post can be seen in context.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.