July 14, 2025, 21:47:00 GMT
permalink Post: 11922533
I cant speak for how long it would take to connect the dots though.
8 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 14, 2025, 22:05:00 GMT
permalink Post: 11922543
I figure you are already well aware of the following, but I mention it to avoid others reading more into the words than was intended: the report doesn't confirm whether or not the CCTV still in Figure 15 is the first frame where the RAT can be seen fully deployed.
2 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 14, 2025, 22:27:00 GMT
permalink Post: 11922550
Switching off the engines would cut power. (the RAT deployed before they overflew the end of the runway) The HUD would go blank. As would most of the display units. The lighting would change. The hissing of conditioned air would stop. Various 'noises' would cease. The engines sound would change dramatically, and they would feel the deceleration. The one EICAS screen remaining would be generating all sorts of messages. It would be obvious that power was lost.
I cant speak for how long it would take to connect the dots though.
I cant speak for how long it would take to connect the dots though.
https://data.ntsb.gov/Docket/Documen...man-Master.PDF )
Last edited by D Bru; 14th July 2025 at 22:39 .
4 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 15, 2025, 16:59:00 GMT
permalink Post: 11923087
Having read through most of the posts in this and the other threads, and the preliminary report a few times in parts, am mystified by this:
The Preliminary Report states: "The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed during the initial climb immediately after lift-off (fig. 15). No significant bird activity is observed in the vicinity of the flight path. The aircraft started to lose altitude before crossing the airport perimeter wall."
Does this mean the RAT deployed "immediately after" in the sense of within 1 second after lift-off?
We, as a group, certainly seem to be interpreting the "immediately thereafter" in a prior paragraph to mean that the E1 and E2 fuel cutoff switches went RUN -> CUTOFF within 1 second or so after max airspeed of 180kts at 08:08:42.
The prior paragraph for quick ref:
"The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, 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. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off."
Additionally, have to say, this PR has a few major weaknesses in it:
- no timestamp for RAT deployment, though RAT hydraulic power coming online has one; also is it for initial power or rated power?
- no timestamp for the pilot conversation about 'cutoff', though it is provided for the MAYDAY.
- no timestamps for E1/E2 Fuel Cutoff Switches going from RUN -> CUTOFF, though they're provided for CUTOFF -> RUN.
The Preliminary Report states: "The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed during the initial climb immediately after lift-off (fig. 15). No significant bird activity is observed in the vicinity of the flight path. The aircraft started to lose altitude before crossing the airport perimeter wall."
Does this mean the RAT deployed "immediately after" in the sense of within 1 second after lift-off?
We, as a group, certainly seem to be interpreting the "immediately thereafter" in a prior paragraph to mean that the E1 and E2 fuel cutoff switches went RUN -> CUTOFF within 1 second or so after max airspeed of 180kts at 08:08:42.
The prior paragraph for quick ref:
"The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42 UTC and immediately thereafter, 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. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off."
Additionally, have to say, this PR has a few major weaknesses in it:
- no timestamp for RAT deployment, though RAT hydraulic power coming online has one; also is it for initial power or rated power?
- no timestamp for the pilot conversation about 'cutoff', though it is provided for the MAYDAY.
- no timestamps for E1/E2 Fuel Cutoff Switches going from RUN -> CUTOFF, though they're provided for CUTOFF -> RUN.
Last edited by T28B; 15th July 2025 at 17:15 . Reason: formatting errors fixed.
3 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 15, 2025, 17:40:00 GMT
permalink Post: 11923111
Since the preliminary report neglected including when the RAT deployment occurred, I've tried to estimate it based on the picture they did include:
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 16, 2025, 00:30:00 GMT
permalink Post: 11923360
Since the preliminary report neglected including when the RAT deployment occurred, I've tried to estimate it based on the picture they did include:
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
I'm equally impressed by how quickly No1 engine recovered. I think it's safe to say that this situation is not recoverable, but a truly impressive piece of engineering all the same.
3 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 16, 2025, 01:55:00 GMT
permalink Post: 11923383
Since the preliminary report neglected including when the RAT deployment occurred, I've tried to estimate it based on the picture they did include:
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
Baro altitude should be around 150ft; using the public cctv video, I estimate this picture was taken between 4-7 seconds after rotation. A wide range, but that was the best estimate I could come up with. Maybe someone else could narrow it down further.
1. ADSB readouts - according to FlightRadar24, the last ADSB transmission was at 71ft AGL. Is that significant given the RAT is seen already deployed at 150ft AGL per the estimate above? At 71ft AGL, the wheels are about 40-50ft off the ground, assuming aircraft attitude is unchanged between there and this image. Is that 1 or 2 seconds after rotation? Does this imply electrical issues?
1a. The timings for ADSB transmissions outlined by MrShed are not in sync with the estimates above - people have talked about a time shift in this thread. I do believe ADSB timestamps are by the receiving station.
2. The preliminary report timings from the EAFR for E2 fuel cutoff switch RUN -> CUTOFF to the RAT supplying hydraulic power disagree with the lower end of the 4-7s estimate above, and are only consistent if this picture was taken 6-7 seconds after rotation, in my opinion, because of the time (4-5s) it would take to cut off the fuel to E2, spool down to where the VFSGs stop providing AC power, and RAT deployment.
3. The Preliminary Report mentions that the RAT deployed "immediately after" lift-off. Again, I have to wonder, why didn't they provide the RAT deployment timestamp, even relative to rotation? If this is in fact the case, does this imply electrical issues, in line with the last ADSB altitude reading?
FR24 article https://www.flightradar24.com/blog/f...rom-ahmedabad/
Last edited by appruser; 16th July 2025 at 01:57 . Reason: Added link to FR24 blog post
1 user liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 16, 2025, 03:52:00 GMT
permalink Post: 11923409
This was posted sometime ago, but if anyone would still find it useful to pinpoint the location of the aircraft in the 'new' photo from the Preliminary Report (with RAT deployed) I made a crude attempt which placed it roughly midway between the two sets of identical touchdown zone markings, ~245m (803 ft) from the displaced threshold of RW05.
The deemed position of the CCTV camera is only an estimate, based on visual cues. I'm happy to share my workings, should anyone find it useful to cross-reference this with other data they are working on, but I will avoid cluttering up the thread any further until/unless it becomes relevant.
You're looking for the point where the LEFT of the two white lines intersects the runway (ignore the white dots):
The deemed position of the CCTV camera is only an estimate, based on visual cues. I'm happy to share my workings, should anyone find it useful to cross-reference this with other data they are working on, but I will avoid cluttering up the thread any further until/unless it becomes relevant.
You're looking for the point where the LEFT of the two white lines intersects the runway (ignore the white dots):
Generally don't think it's a good idea to reply to own posts, but in this case wanted to keep things in context. A few interesting items of note:
1. ADSB readouts - according to FlightRadar24, the last ADSB transmission was at 71ft AGL. Is that significant given the RAT is seen already deployed at 150ft AGL per the estimate above? At 71ft AGL, the wheels are about 40-50ft off the ground, assuming aircraft attitude is unchanged between there and this image. Is that 1 or 2 seconds after rotation? Does this imply electrical issues?
1a. The timings for ADSB transmissions outlined by MrShed are not in sync with the estimates above - people have talked about a time shift in this thread. I do believe ADSB timestamps are by the receiving station.
2. The preliminary report timings from the EAFR for E2 fuel cutoff switch RUN -> CUTOFF to the RAT supplying hydraulic power disagree with the lower end of the 4-7s estimate above, and are only consistent if this picture was taken 6-7 seconds after rotation, in my opinion, because of the time (4-5s) it would take to cut off the fuel to E2, spool down to where the VFSGs stop providing AC power, and RAT deployment.
3. The Preliminary Report mentions that the RAT deployed "immediately after" lift-off. Again, I have to wonder, why didn't they provide the RAT deployment timestamp, even relative to rotation? If this is in fact the case, does this imply electrical issues, in line with the last ADSB altitude reading?
FR24 article https://www.flightradar24.com/blog/f...rom-ahmedabad/
1. ADSB readouts - according to FlightRadar24, the last ADSB transmission was at 71ft AGL. Is that significant given the RAT is seen already deployed at 150ft AGL per the estimate above? At 71ft AGL, the wheels are about 40-50ft off the ground, assuming aircraft attitude is unchanged between there and this image. Is that 1 or 2 seconds after rotation? Does this imply electrical issues?
1a. The timings for ADSB transmissions outlined by MrShed are not in sync with the estimates above - people have talked about a time shift in this thread. I do believe ADSB timestamps are by the receiving station.
2. The preliminary report timings from the EAFR for E2 fuel cutoff switch RUN -> CUTOFF to the RAT supplying hydraulic power disagree with the lower end of the 4-7s estimate above, and are only consistent if this picture was taken 6-7 seconds after rotation, in my opinion, because of the time (4-5s) it would take to cut off the fuel to E2, spool down to where the VFSGs stop providing AC power, and RAT deployment.
3. The Preliminary Report mentions that the RAT deployed "immediately after" lift-off. Again, I have to wonder, why didn't they provide the RAT deployment timestamp, even relative to rotation? If this is in fact the case, does this imply electrical issues, in line with the last ADSB altitude reading?
FR24 article https://www.flightradar24.com/blog/f...rom-ahmedabad/
Note that the good folks at FR24 did not apply temperature correction to the barometric altitude (they corrected for air pressure and runway elevation); pilots on pprune have done the corrections themselves and arrived at slightly different values, so take those altitude numbers with a grain of salt. Note also that the 787 sends altitude in 25 ft. increments, and I don't know how these are rounded (up, down, nearest).
We do not know how long the RAT has been deployed in this photo, we only know it can't have been deployed later. I have learned on this thread that the CUTOFF switch will also cause the VFSGs to disconnect, i.e. the B787 systems will electrically isolate the engine from the power buses before it has spooled down. With a dual failure, this would leave the main buses unpowered in short order, so if all of this is correct, the RAT would have clonked into place very soon after the second engine was cut off. This would not depend on the turbine speed.
I personally do not know what items are logged on the flight recorder, but I imagine RAT deployment was not among them. If so, the conditions for its deployment would be logged, but it requires an analytical step to conclude it did, and a preliminary report typically has no analysis at all. Hydraulic pressure to the flight controls is likely logged, so the RAT delivering hydraulic power would be a matter of record.
Where is the RadAlt antenna on a 787? Is it in the nose, or further back between the main gears?
Last edited by Musician; 16th July 2025 at 04:02 .
3 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 16, 2025, 07:14:00 GMT
permalink Post: 11923479
The deployment of RAT has announced Double Engine failure. Also the AutoStart of APU pretty much indicates the same thing . Release of CVR will definitely help.
1 user liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 16, 2025, 07:16:00 GMT
permalink Post: 11923480
1 user liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 16, 2025, 13:57:00 GMT
permalink Post: 11923742
As I've previously posted, there is the fact that the ADS-B data (in your diagram) continues long after electrical power from the engines would have been lost. Someone recently posted that the engines don't even need to run down for this to happen, saying that operation of the FCS to cutoff would shut down the engine VFSG's.
https://fliphtml5.com/quwam/qhdw/Boo...cs_Electrical/ (page 96)
I don't know if the transponder is on the captain's instrument bus, but if so, it would have power from the main battery while the RAT is being deployed.
We are definitely seeing the loss of thrust in the ADS-B data.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 16, 2025, 22:37:00 GMT
permalink Post: 11924040
The recorded switch position data, the recorded engine performance data, the aircraft performance and trajectory after take off, the RAT deployment and open/ing APU inlet, the cockpit voice recording that has been selectively and carefully paraphrased in the preliminary report and the physical and electrical design and separation of the switches and the wiring for each system prove, to whatever standard of proof anyone wants to nominate, that BOTH fuel cut off switches were physically switched OFF 'shortly' after take off, then BOTH switches were physically switched back ON 'shortly' thereafter.
Give the FSC switch/wiring defect theory away, hamsters.
Give the FSC switch/wiring defect theory away, hamsters.
13 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 18, 2025, 00:25:00 GMT
permalink Post: 11924773
So I've looked again and I think that basically the ADS-B data is 5 seconds out.
So in the diagram (can't modify right now but I will), the blue bar starts at 5 and ends at 13, max altitude marker at 8.
That would tie in with loss of power.
It would put, interestingly, engine cutoffs right at the earliest opportunity within the window available with sampling etc.
(Incidentally an apology to Musician who I incorrectly told earlier that such a movement would be inconsistent with max altitude record, I can see clearly now this isn't the case!).
So in the diagram (can't modify right now but I will), the blue bar starts at 5 and ends at 13, max altitude marker at 8.
That would tie in with loss of power.
It would put, interestingly, engine cutoffs right at the earliest opportunity within the window available with sampling etc.
(Incidentally an apology to Musician who I incorrectly told earlier that such a movement would be inconsistent with max altitude record, I can see clearly now this isn't the case!).
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 .
Last edited by appruser; 18th July 2025 at 00:41 . Reason: added a comma for clarity
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 18, 2025, 01:32:00 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 .
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.
2 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 18, 2025, 03:43:00 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.
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 04:03 . Reason: fixed heights
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
July 18, 2025, 05:07:00 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 .
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 .
2 users liked this post.
Reply to this quoting this original post. You need to be logged in. Not available on closed threads.