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1stspotter
2025-06-14T20:13:00 permalink Post: 11901794 |
https://www.flightradar24.com/blog/f...rom-ahmedabad/ 1 user liked this post. |
1stspotter
2025-06-14T20:19:00 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... ![]() 2 users liked this post. |
AirScotia
2025-06-14T20:20:00 permalink Post: 11901800 |
I've been 'watching' flights take off from Ahmedabad on FR24. Assuming that the bold dots on the track are where FR24 gets some real transponder data, it looks as if flights become visible at take-off, then FR24 interpolates the track until roughly 800m/1km from the end of the runway when it gets the next 'real' data block. So all we can conclude is that the transponder stopped transmitting somewhere in the 8 - 10 seconds between take-off and 1km.
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Mrshed
2025-06-14T20:31:00 permalink Post: 11901804 |
1) that the data stopped around about time of peak AGL - we knew this already. 2) that the flight path was much shallower *before* whatever event caused the data to stop (note that this data should be accurate in comparison even if not in absolute). The second point would presumably imply whatever the issue was, it wasn't solely something that happened instantaneously once the decline began, but rather at least two events (presumably not independent) - one that impaired flight, and one that stopped the data transmission (and also likely impaired flight further). 1 user liked this post. |
DaveReidUK
2025-06-14T20:42:00 permalink Post: 11901815 |
I've been 'watching' flights take off from Ahmedabad on FR24. Assuming that the bold dots on the track are where FR24 gets some real transponder data, it looks as if flights become visible at take-off, then FR24 interpolates the track until roughly 800m/1km from the end of the runway when it gets the next 'real' data block. So all we can conclude is that the transponder stopped transmitting somewhere in the 8 - 10 seconds between take-off and 1km.
For everyday flights, FR24 displays enough plot points to produce a reasonably smooth track, with plots typically at 6-8 second intervals, while suppressing intermediate points to save bandwidth. That's why the initial download for the accident flight only had 4 plot points. The supplementary "granular" data (FR24's description) contains plots towards the end of the takeoff roll at roughly 0.5 second intervals. So we can reasonably conclude that the aircraft's transponder stopped squittering within a second (probably less) of the final plot point. 1 user liked this post. |
SQUAWKIDENT
2025-06-14T20:59:00 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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DaveReidUK
2025-06-14T21:21:00 permalink Post: 11901849 |
What don't you believe in the published data? 5 users liked this post. |
Compton3fox
2025-06-15T07:34:00 permalink Post: 11902190 |
No evidence of engine failure
No evidence of RAT deployment from a poor image. No evidence of electrical failure. The teams of lawyers in the UK representing 53 grieving families will be working over the weekend to sign up said families to a class action. This is going to get messy. No evidence of RAT deployment from a poor image . - You can argue Not from the Image but...: 2 independent audio analysis of the video audio shows the sound comes from a deployed RAT plus JB's video. Plus the guys who live in SEA having heard 100's of RATs deployed during test flight have stated that the sound is a RAT. No evidence of electrical failure . - Not true. Reported cabin emergency lights going off, FR24 feed stopped just as in the 737 South Korea incident in December. APU intake door partially open at crash scene, suggesting an APU autostart. Now you can call into question the above evidence but to state there is none, is simply not true. Last edited by Compton3fox; 15th Jun 2025 at 08:23 . 12 users liked this post. |
MR8
2025-06-15T12:07:00 permalink Post: 11902414 |
Altitude reached AAL
No, they did not climb that high. Latest FR24 ADS-B report was indeed 625 ft, but that is based on 1013 (STD). With the local QNH being 1000, that 625ft becomes roughly 300ft MSL. Corrected for airport elevation, this is just above 100ft. The last recorded altitude of the aircraft was roughly 100ft AGL, which does not mean it didn\x92t climb a bit higher, but the aircraft reaching 400ft is pure speculation.
2 users liked this post. |
NOC40
2025-06-15T15:05:00 permalink Post: 11902536 |
Flightradar24 (I know, I know) has a short blog on the (very minimal) ADS-B data available. There's only around 4s of useful data available from 21ft o 71ft altitude (last packet received 0.8s later), But: it's odd seeing the speed DROPPING shortly after takeoff. Even if you calculate total energy (kinetic + potential) it's falling, i.e. the engines aren't producing thrust. (In fairness reported speed doesn't match my calculated speeds, but even with mine I don't see power). Also: if you assumed no thrust from 71ft AGL @ 172kt you'd reach 250ft at 160kt. Isn't that roughly where they ended up? Noisy data, but this suggests the engines stopped producing power almost as soon as the wheels left the ground. (If someone could download a CSV of another similar flight and send to me I can do a compare and contrast of Total Energy)
![]() ![]() ![]() 6 users liked this post. |
Gupeg
2025-06-15T16:46:00 permalink Post: 11902623 |
Flightradar24 (I know, I know) has a short blog on the (very minimal) ADS-B data available. There's only around 4s of useful data available from 21ft o 71ft altitude (last packet received 0.8s later), But: it's odd seeing the speed DROPPING shortly after takeoff. Even if you calculate total energy (kinetic + potential) it's falling, i.e. the engines aren't producing thrust. (In fairness reported speed doesn't match my calculated speeds, but even with mine I don't see power). Also: if you assumed no thrust from 71ft AGL @ 172kt you'd reach 250ft at 160kt. Isn't that roughly where they ended up? Noisy data, but this suggests the engines stopped producing power almost as soon as the wheels left the ground. (If someone could download a CSV of another similar flight and send to me I can do a compare and contrast of Total Energy)
1. You might mathematically start at TE=0 at start of takeoff-roll, and treat drag as minimal until rotation. 2. Typically rotation will be to say 15deg nose up, but flight path will be much less (5deg? for heavy hot 787). Once that rotation is complete, aircraft will stop accelerating. Therefore engine thrust (energy gain) equals gain in PE - drag x time. 3. This might give a better insight into where energy gain/loss became unusual? Looking at the raw data in your post, and given the speeds are likely IAS based i.e. can be affected by wind, I don't see the IAS loss as equating to dual engine failure i.e. zero thrust - but could be wrong. Once a heavy airliner gets to lift off the acceleration is reduced (drag) and the decays to zero as PE gain kicks in. Ditto a time / distance to the crash site might give some energy info? Looks like the crash site is 50' (?) below the airfield (Google Earth will give more). I think you are doing an interesting study on the absence of other info ![]() |
andihce
2025-06-15T18:32:00 permalink Post: 11902696 |
Flightradar24 (I know, I know) has a short blog on the (very minimal) ADS-B data available. There's only around 4s of useful data available from 21ft o 71ft altitude (last packet received 0.8s later), But: it's odd seeing the speed DROPPING shortly after takeoff. Even if you calculate total energy (kinetic + potential) it's falling, i.e. the engines aren't producing thrust. (In fairness reported speed doesn't match my calculated speeds, but even with mine I don't see power). Also: if you assumed no thrust from 71ft AGL @ 172kt you'd reach 250ft at 160kt. Isn't that roughly where they ended up? Noisy data, but this suggests the engines stopped producing power almost as soon as the wheels left the ground. (If someone could download a CSV of another similar flight and send to me I can do a compare and contrast of Total Energy)
For instance, what about induced drag (admittedly much complicated, I imagine, by varying ground effect) once rotation begins? A comparison with another 787-8 flight from the same runway and under similar conditions (meteorological, load, etc.) might be ideal. Are there not tools accessible to ordinary users for making detailed such simulations, rather than a back of the envelope calculation? I daresay Boeing has made such simulations already, and have a pretty good idea of whether and when thrust loss might have occurred. |
DIBO
2025-06-15T22:56:00 permalink Post: 11902931 |
According to Flightradar24 data, the aircraft ascended to a maximum barometric altitude of just 625 feet\x97around 425 feet above the airport\x92s 200‑foot elevation\x97before descending at approximately 475 feet per minute.
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appruser
2025-06-16T06:59:00 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) 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. |
JustusW
2025-06-16T09:42:00 permalink Post: 11903330 |
Im a layman who knows nothing and am just a PPL and am fascinated by the technicals.So does the computer store the recommended flap setting given all the information entered and then decide whether the actual setting used is appropriate and spits out a warning of checklist complete?what would happen if use of the full runway was entered into the computer, but actually they entered at an intersection, surely the info would be wrong ?...
In addition the valid settings for takeoff flaps simply begin at 5\xb0, so anything less isn't even offered. The corresponding alarms will thus always trigger if you don't have at least 5\xb0 flaps set upon setting takeoff thrust, possibly requiring a higher setting depending on the calculated takeoff configuration. As mentioned before in this thread the loading of the accident aircraft should have been far below its maximums, so a 5\xb0 flaps takeoff is quite ordinary, and the aircraft left the runway well short of its end. Also the aircraft used the entire runway after backtracking along it since there are no taxiways going that far. This information has been corrected by FR24 a while ago and stems from the incomplete GPS positional data that is inherent in ADS-B tracking, especially on the ground. 1 user liked this post. |
JustusW
2025-06-16T09:42:00 permalink Post: 11903756 |
Im a layman who knows nothing and am just a PPL and am fascinated by the technicals.So does the computer store the recommended flap setting given all the information entered and then decide whether the actual setting used is appropriate and spits out a warning of checklist complete?what would happen if use of the full runway was entered into the computer, but actually they entered at an intersection, surely the info would be wrong ?...
In addition the valid settings for takeoff flaps simply begin at 5\xb0, so anything less isn't even offered. The corresponding alarms will thus always trigger if you don't have at least 5\xb0 flaps set upon setting takeoff thrust, possibly requiring a higher setting depending on the calculated takeoff configuration. As mentioned before in this thread the loading of the accident aircraft should have been far below its maximums, so a 5\xb0 flaps takeoff is quite ordinary, and the aircraft left the runway well short of its end. Also the aircraft used the entire runway after backtracking along it since there are no taxiways going that far. This information has been corrected by FR24 a while ago and stems from the incomplete GPS positional data that is inherent in ADS-B tracking, especially on the ground. |
Back office Penguin
2025-06-17T00:56:00 permalink Post: 11903897 |
Looking at the detailed ADS-B data released by FR24 and the June 10 AI171 data, I noticed that the two flights show the following data at similar points in the takeoff phase
Height :575ft Speed :182kts Even though it is impossible that the takeoff weight and outside air conditions are the same on the two flights, we guess that there was nothing wrong at this moment. |
Capn Bloggs
2025-06-17T14:17:00 permalink Post: 11904336 |
Originally Posted by
Squawk7700
Perhaps?
Originally Posted by
Squawk7700
"LNAV" - "VNAV" or "FLCH SPD" To ensure:
VNAV or FLCH was NOT engaged
after liftoff.
Pilot assumed A/T was managing thrust, but it wasn’t.
Pilot assumed A/T was managing thrust, but it wasn’t.
Thrust stayed fixed or decayed (if levers were moved).
​​​​​​​Speed decayed, aircraft climbed too steeply, energy bled off.
​​​​​​​Pilot assumed engine failure due to poor climb response.
Boeing SOPs typically include a callout at 400 ft like:
"LNAV" - "VNAV" or "FLCH SPD" To ensure:
You're clearly implying a complete ballsup by the crew, making multiple serious mistakes or errors of omission. Last edited by T28B; 17th Jun 2025 at 15:40 . Reason: formatting clean up 9 users liked this post. |
Capn Bloggs
2025-06-18T01:02:00 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/ 1 user liked this post. |
EXDAC
2025-06-18T01:33:00 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/ ![]() 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 Jun 2025 at 01:54 . Reason: revise image to add missing data point 1 user liked this post. |