June 12, 2025, 22:02:00 GMT
permalink Post: 11899778
OK, I promised some informed speculation when I got back, so here goes:
Disclaimer: never worked the 787, so my detailed knowledge is a bit lacking.
First off, this is perplexing - especially if the RAT was deployed. There is no 'simple' explanation that I can come up with.
GEnx-1B engines have been exceptionally reliable, and the GE carbon composite fan blades are very robust and resistant to bird strike damage (about 15 years after the GE90 entry into service, I remember a GE boast that no GE90 (carbon composite) fan blades had needed to be scrapped due to damage (birdstrike, FOD, etc. - now that was roughly another 15 years ago, so is probably no longer true, but it shows just how robust the carbon composite blades are - far better than the more conventional titanium fan blades).
Not saying it wasn't somehow birdstrike related, just that is very unlikely (then again, all the other explanations I can come up with are also very unlikely
).
Using improper temp when calculating TO performance - after some near misses, Boeing added logic that cross-compares multiple total temp probes - aircraft TAT (I think the 787 uses a single, dual element probe for aircraft TAT, but stand to be corrected) and the temp measured by the engine inlet probes - and puts up a message if they disagree by more than a few degree tolerance - so very, very unlikely.
N1 power setting is somewhat less prone to measurement and power setting errors than EPR (N1 is a much simpler measurement than Rolls EPR) - although even with EPR, problems on both engines at the same time is almost unheard of.
The Auto Thrust (autothrottle) function 'falls asleep' at 60 knots - and doesn't unlock until one of several things happens - 250 knots, a set altitude AGL is exceeded (I'm thinking 3,000 ft. but the memory is fuzzy), thrust levers are moved more than a couple of degrees, or the mode select is changed (memory says that last one is inhibited below 400 ft. AGL). So an Auto Thrust malfunction is also extremely unlikely. Further, a premature thrust lever retard would not explain a RAT deployment.
TO does seem to be very late in the takeoff role - even with a big derate, you still must accelerate fast enough to reach V1 with enough runway to stop - so there is still considerable margin if both engines are operating normally. That makes me wonder if they had the correct TO power setting - but I'm at a loss to explain how they could have fouled that up with all the protections that the 787 puts on that.
If one engine did fail after V1, it's conceivable that they shut down the wrong engine - but since this happened literally seconds after takeoff, it begs the question why they would be in a big hurry to shut down the engine. Short of an engine fire, there is nothing about an engine failure that requires quick action to shut it down - no evidence of an engine fire, and even with an engine fire, you normally have minutes to take action - not seconds.
The one thing I keep thinking about is someone placing both fuel switches to cutoff immediately after TO. Yes, it's happened before (twice - 767s in the early 1980s), but the root causes of that mistake are understood and have been corrected. Hard to explain how it could happen (unless, God forbid, it was intentional).
Disclaimer: never worked the 787, so my detailed knowledge is a bit lacking.
First off, this is perplexing - especially if the RAT was deployed. There is no 'simple' explanation that I can come up with.
GEnx-1B engines have been exceptionally reliable, and the GE carbon composite fan blades are very robust and resistant to bird strike damage (about 15 years after the GE90 entry into service, I remember a GE boast that no GE90 (carbon composite) fan blades had needed to be scrapped due to damage (birdstrike, FOD, etc. - now that was roughly another 15 years ago, so is probably no longer true, but it shows just how robust the carbon composite blades are - far better than the more conventional titanium fan blades).
Not saying it wasn't somehow birdstrike related, just that is very unlikely (then again, all the other explanations I can come up with are also very unlikely
).
Using improper temp when calculating TO performance - after some near misses, Boeing added logic that cross-compares multiple total temp probes - aircraft TAT (I think the 787 uses a single, dual element probe for aircraft TAT, but stand to be corrected) and the temp measured by the engine inlet probes - and puts up a message if they disagree by more than a few degree tolerance - so very, very unlikely.
N1 power setting is somewhat less prone to measurement and power setting errors than EPR (N1 is a much simpler measurement than Rolls EPR) - although even with EPR, problems on both engines at the same time is almost unheard of.
The Auto Thrust (autothrottle) function 'falls asleep' at 60 knots - and doesn't unlock until one of several things happens - 250 knots, a set altitude AGL is exceeded (I'm thinking 3,000 ft. but the memory is fuzzy), thrust levers are moved more than a couple of degrees, or the mode select is changed (memory says that last one is inhibited below 400 ft. AGL). So an Auto Thrust malfunction is also extremely unlikely. Further, a premature thrust lever retard would not explain a RAT deployment.
TO does seem to be very late in the takeoff role - even with a big derate, you still must accelerate fast enough to reach V1 with enough runway to stop - so there is still considerable margin if both engines are operating normally. That makes me wonder if they had the correct TO power setting - but I'm at a loss to explain how they could have fouled that up with all the protections that the 787 puts on that.
If one engine did fail after V1, it's conceivable that they shut down the wrong engine - but since this happened literally seconds after takeoff, it begs the question why they would be in a big hurry to shut down the engine. Short of an engine fire, there is nothing about an engine failure that requires quick action to shut it down - no evidence of an engine fire, and even with an engine fire, you normally have minutes to take action - not seconds.
The one thing I keep thinking about is someone placing both fuel switches to cutoff immediately after TO. Yes, it's happened before (twice - 767s in the early 1980s), but the root causes of that mistake are understood and have been corrected. Hard to explain how it could happen (unless, God forbid, it was intentional).
Last edited by T28B; 12th June 2025 at 22:21 . Reason: white space is your friend, and is reader-friendly
June 12, 2025, 22:07:00 GMT
permalink Post: 11899780
... Specifically, I live in Lynnwood, Washington directly under the approach path for Paine Field's runway 34 Left, and I've been there since 2007. I lived in Mukilteo from 2000-2007, which is more next to the runway than under it... Boeing manufactures the 777 and 787 at Paine field....The RAT is deployed and tested during EVERY SINGLE first flight of every aircraft Boeing produces that has a RAT installed. And sometimes it requires a re-test on subsequent flights.
So yeah, I have heard a deployed RAT, from the ground, HUNDREDS of times. I've heard it while preflighting my airplane, I've heard it while mowing my lawn, I've heard while lying in bed. And this is exactly what they always sounds like....
So yeah, I have heard a deployed RAT, from the ground, HUNDREDS of times. I've heard it while preflighting my airplane, I've heard it while mowing my lawn, I've heard while lying in bed. And this is exactly what they always sounds like....
NOT especially getting at you slacktide , indeed thanks for the followup and presenting your experience/reasoning, however, to assist everyone, including *relevant* background/support detail with one's post is to be encouraged! If you don't have this, or are just speculating from a position of little experience or knowledge, maybe the best contribution would be to sit on your hands for a bit and learn from others?
FP.
June 12, 2025, 22:50:00 GMT
permalink Post: 11899809
So, looking around the interwebs it seems like the 787 RAT takes 8 seconds to deploy, and only provides full RAT power at 130 knots or better.
Does it seem like the RAT should already be deployed in the videos we have seen, given an 8 second deployment time, and adding in the time needed for the system or pilot to decide it should be deployed?
It must take a little time for the engines to spool down and the other power sources to fail after takeoff.
Does it seem like the RAT should already be deployed in the videos we have seen, given an 8 second deployment time, and adding in the time needed for the system or pilot to decide it should be deployed?
It must take a little time for the engines to spool down and the other power sources to fail after takeoff.
June 12, 2025, 23:12:00 GMT
permalink Post: 11899824
I'm reminded a little of Emirates EK321, back in 2021, where the pilots left the MCP altitude setting at 0ft.
https://simpleflying.com/emirates-bo...-long-takeoff/
However, that would have nothing to do with the RAT deployment.
However, that would have nothing to do with the RAT deployment.
June 12, 2025, 23:12:00 GMT
permalink Post: 11899825
So, I'm in no way connected with Aviation, but I am a bit of a data geek and hope it's an appropriate thing to post. I was interested to see how this flight related to others, so did a bit of data wrangling with FlightRadar and Google Earth. This obviously comes with some caveats:
- The data may not be reliable, coverage could be patchy and FlightRadar probably do some data processing that they don't reveal.
That said, what I did was for the past 7 days of this flight - i.e. 787s travelling to Gatwick I downloaded the raw .CSV data for each flight. From that I took the first sample with an altitude of >0 i.e. the first point that the flight looked to be airborne. On my picture (which I've tried to show in 3D as far as possible), these are labelled as 1-1, 2-1, 3-1 etc and orange. As I don't have enough posts to include the visualisation, here it is:
postimg.cc/gLW8zXDg
The flight from today is in red with a larger marker. As you can see, it appears to be in the same position in space as every other flight this week at the same point in time (with all the caveats above). It did, however, have a ground speed approx. 10knts less than any other flight this week. Is that significant? I don't know. It certainly isn't airspeed anyway, so may not mean much.
I remember reading a quote from FlightRadar somewhere in this thread that this was the last valid sample from this flight. Obviously, given the course of events we wouldn't expect many samples, so the next thing I did was to take the second valid row of data from each flight and plot that (in green 2-1, 2-2, 2-3 etc) - what this showed that all of the other flights in the last week did manage to transmit a data point before they flew over the crash site so had todays flight transmitted anything there is a reasonable chance that it would have been picked up in a similar location to the others. That is wasn't seems to suggest there is a good chance that the data wasn't sent. One possibility could be a loss of power, but I'm sure there are many other factors that could result in missing a data point.
I don't want to draw too many conclusions from this because the data is probably not that reliable but it does seem to suggest a fairly normal take off that didn't get close to over running the runway.
Does it correspond to the reported bang, RAT deployment, etc? Maybe.
- The data may not be reliable, coverage could be patchy and FlightRadar probably do some data processing that they don't reveal.
That said, what I did was for the past 7 days of this flight - i.e. 787s travelling to Gatwick I downloaded the raw .CSV data for each flight. From that I took the first sample with an altitude of >0 i.e. the first point that the flight looked to be airborne. On my picture (which I've tried to show in 3D as far as possible), these are labelled as 1-1, 2-1, 3-1 etc and orange. As I don't have enough posts to include the visualisation, here it is:
postimg.cc/gLW8zXDg
The flight from today is in red with a larger marker. As you can see, it appears to be in the same position in space as every other flight this week at the same point in time (with all the caveats above). It did, however, have a ground speed approx. 10knts less than any other flight this week. Is that significant? I don't know. It certainly isn't airspeed anyway, so may not mean much.
I remember reading a quote from FlightRadar somewhere in this thread that this was the last valid sample from this flight. Obviously, given the course of events we wouldn't expect many samples, so the next thing I did was to take the second valid row of data from each flight and plot that (in green 2-1, 2-2, 2-3 etc) - what this showed that all of the other flights in the last week did manage to transmit a data point before they flew over the crash site so had todays flight transmitted anything there is a reasonable chance that it would have been picked up in a similar location to the others. That is wasn't seems to suggest there is a good chance that the data wasn't sent. One possibility could be a loss of power, but I'm sure there are many other factors that could result in missing a data point.
I don't want to draw too many conclusions from this because the data is probably not that reliable but it does seem to suggest a fairly normal take off that didn't get close to over running the runway.
Does it correspond to the reported bang, RAT deployment, etc? Maybe.
June 13, 2025, 00:12:00 GMT
permalink Post: 11899855
From the airport CCTV video it looks to me like a normal takeoff and start of climb, until suddenly there's a loss of climb performance with no obvious upset at that point. From the picture of the wing post crash it looks like the flaps were still deployed (N.B. based on pre-accident photos that's the right wing so closest to the camera is aileron and flaps are further away, damage had me confused first time), so I'm going with loss of thrust rather than flap retraction.
From the videos from bystanders it looks like RAT deployment (both sound and zoomed in pictures) rather than thrust lever retard, and that would also explain failure to retract gear - if you are dealing with both engines out at that altitude then gear isn't your first thought. From the airport CCTV video I don't see anything that looks like bird strikes at that point in the climb i.e. no obvious flocks of birds, no smoke out of the engines, no slewing one way as one engine fails and then the other is cut by accident - plus you wouldn't cut the engine at that point, you'd climb on one engine and then sort it out.
Even fuel contamination or water build up in both tanks is likely to result in one engine failing a few seconds before the other. So I can't come up with anything other than both fuel cutoff switches that would result in loss of thrust and RAT deployment. Looking at a picture of the cutoff switches https://www.nycaviation.com/2013/08/...is-fired/30179 I don't see how they get hit by accident.
I'm confused, hope we get an FDR / CVR readout soon.
From the videos from bystanders it looks like RAT deployment (both sound and zoomed in pictures) rather than thrust lever retard, and that would also explain failure to retract gear - if you are dealing with both engines out at that altitude then gear isn't your first thought. From the airport CCTV video I don't see anything that looks like bird strikes at that point in the climb i.e. no obvious flocks of birds, no smoke out of the engines, no slewing one way as one engine fails and then the other is cut by accident - plus you wouldn't cut the engine at that point, you'd climb on one engine and then sort it out.
Even fuel contamination or water build up in both tanks is likely to result in one engine failing a few seconds before the other. So I can't come up with anything other than both fuel cutoff switches that would result in loss of thrust and RAT deployment. Looking at a picture of the cutoff switches https://www.nycaviation.com/2013/08/...is-fired/30179 I don't see how they get hit by accident.
I'm confused, hope we get an FDR / CVR readout soon.
June 13, 2025, 01:01:00 GMT
permalink Post: 11899888
June 13, 2025, 01:14:00 GMT
permalink Post: 11899895
Firstly, condolences to all those involved.
Secondly the above is a load of rubbish, as someone who also 'trains and checks' pilots and also has many years of Safety Investigation within large airlines it is a semi regular occurrence to depart with incorrect or no data.
Tiger took off in Sydney with NO data in the FMGC,
Singapore had a tail strike in AKL after inserting the ZFW as the TOW
Emirates almost crashed in MEL for similar reasons.
Not saying that this happened here
Air NZ a few years ago almost put a 787 in the water out of Rarotonga as they had 100' in the FCU, took off, engaged autopilot and the aircraft pitched down and thrust came off, pilots recovered it at 60agl.
Emirates has done similar, so these things happen.
Clearly we don't know what happened here but I think it fair to assume it went wrong at rotate given the gear stayed down which would suggest a distraction at that point.
Secondly the above is a load of rubbish, as someone who also 'trains and checks' pilots and also has many years of Safety Investigation within large airlines it is a semi regular occurrence to depart with incorrect or no data.
Tiger took off in Sydney with NO data in the FMGC,
Singapore had a tail strike in AKL after inserting the ZFW as the TOW
Emirates almost crashed in MEL for similar reasons.
Not saying that this happened here
Air NZ a few years ago almost put a 787 in the water out of Rarotonga as they had 100' in the FCU, took off, engaged autopilot and the aircraft pitched down and thrust came off, pilots recovered it at 60agl.
Emirates has done similar, so these things happen.
Clearly we don't know what happened here but I think it fair to assume it went wrong at rotate given the gear stayed down which would suggest a distraction at that point.
PPRuNe, mate, and that gating has long since ended - since about when Danny sold the site.
I empathize with your frustration, and you have no idea how much has already been scrubbed.
There are some wise engineers, ATC pros, and GE/RR experts who are not pilots but who do post here, and whom we'll not bar from discussion.
Do you understand why?
(Yes, we also have examples of Sturgeon's Law in action as well).
I empathize with your frustration, and you have no idea how much has already been scrubbed.
There are some wise engineers, ATC pros, and GE/RR experts who are not pilots but who do post here, and whom we'll not bar from discussion.
Do you understand why?
(Yes, we also have examples of Sturgeon's Law in action as well).
A low altitude in the MCP can become pretty interesting, as will a TAT probe failure to the ATR thrust limit. Both cases will have the thrust levers moving back rapidly. There is no obvious failure of the engines at this point save the question that the RAT may be deployed. A transient electrical fault tripping the logic for the RAT is hard to imagine, but that would possibly end up with an ATR fault and power coming back to idle. Fuel contamination is not impossible, but it is improbable, the engines would have been on their TO configuration from the engine start, and the taxi and turnaround takes enough time to flush the fuel lines, being longer than the selected tank sampling time that sits behind the SOPs. Boeing aircraft are easier for the crew to detect anomalous thrust commands compared to the Airbus, however, if the RAT is out... then more was happening.
The flaps are in the correct position, we are looking at a time critical failure for the crew, they appear to have around 10 seconds between onset and impact, and they have rotated the aircraft in the later stages, as any reasonable pilot would do, and that certainly does not indicate a crew initiated problem on the available information. Unlawful interference is unlikely, given the RT calls that have been made.
The IDGA AAIB is not known for rapid response, this event is of international importance, it appears that it is being treated as such by the authorities involved. The EAFRs on the 787 will tell all soon, and we need that information, this is a globally important aircraft type.
Spoiler
June 13, 2025, 01:27:00 GMT
permalink Post: 11899904
The pilot is being quoted as saying to ATC:
"Mayday...no thrust, losing power, unable to lift"
I don't think a pilot with over 8000 hours experience would mistakenly diagnose that. Also corroborates with the RAT being deployed. Question is how do both engines lose thrust. Bird strike is the obvious one. Fuel contamination seems unlikely.
I see a post above showing how its possible an electrical failure can result in power loss. Passengers on the flight before this said there were issues in the cabin; lights, displays and air con was not working. Again, seems v unlikely to be related.
"Mayday...no thrust, losing power, unable to lift"
I don't think a pilot with over 8000 hours experience would mistakenly diagnose that. Also corroborates with the RAT being deployed. Question is how do both engines lose thrust. Bird strike is the obvious one. Fuel contamination seems unlikely.
I see a post above showing how its possible an electrical failure can result in power loss. Passengers on the flight before this said there were issues in the cabin; lights, displays and air con was not working. Again, seems v unlikely to be related.
June 13, 2025, 01:30:00 GMT
permalink Post: 11899907
The pilot is being quoted as saying to ATC:
"Mayday...no thrust, losing power, unable to lift"
I don't think a pilot with over 8000 hours experience would mistakenly diagnose that. Also corroborates with the RAT being deployed. Question is how do both engines lose thrust. Bird strike is the obvious one. Fuel contamination seems unlikely.
I see a post above showing how its possible an electrical failure can result in power loss. Passengers on the flight before this said there were issues in the cabin; lights, displays and air con was not working. Again, seems v unlikely to be related.
"Mayday...no thrust, losing power, unable to lift"
I don't think a pilot with over 8000 hours experience would mistakenly diagnose that. Also corroborates with the RAT being deployed. Question is how do both engines lose thrust. Bird strike is the obvious one. Fuel contamination seems unlikely.
I see a post above showing how its possible an electrical failure can result in power loss. Passengers on the flight before this said there were issues in the cabin; lights, displays and air con was not working. Again, seems v unlikely to be related.
June 13, 2025, 02:18:00 GMT
permalink Post: 11899930
Determined to be an ergonomics problem with the switch layout in the flightdeck.
Early 767s (JT9D and CF6-80A) had a supervisory "EEC" (Electronic Engine Control - Boeing still uses "EEC" to identify what most people call the FADEC on modern engines). The procedure if an EEC 'failed' was to switch both EECs off (to prevent excessive throttle stagger - unlike FADEC, the engine could operate just fine with a supervisory EEC failed).
Problem was that the EEC ON/OFF switch was located on the aisle stand - right above the fuel cutoff switches. Turned out 'muscle memory' was when the pilot reached down there, it was usually to turn the fuel ON or OFF - which is what they did. Fortunately realizing what he'd done wrong, the pilot quickly restored the switches to RUN and both engines recovered. And yes, they continued on to their destination (RAT was still deployed since there is no way to retract it in-flight).
Previous event was with JT9D engines (United IIRC). In that case, only one engine recovered (second engine went into an unrecoverable stall), they simply came back around and did a single engine landing.
Realizing the ergonomic issue, the EECs were relocated to the pilot's overhead (retrofit by AD).
To the best of my knowledge, there hasn't been a repeat of an inadvertent dual engine shutdown since the EEC switches were relocated. It's also very difficult to 'accidentally' move the switches as there is a locking detent - the switch must be pulled out slightly before it can be moved to CUTOFF.
Last edited by T28B; 13th June 2025 at 02:22 . Reason: again, broke up the text to be reader friendly, great input!
June 13, 2025, 02:34:00 GMT
permalink Post: 11899935
Would not be the first time that an accident has uncovered unintended consequences of a particular fallback configuration that was never able to be checked by either/any of Airbus, McDD or Boeing developmental test-pilots. Thinking of the automatic thrust augment/restoration on the MD81 (regn OY-KHO) that crashed 27Dec91 near Gottrora in Sweden (double engine failure). Design Boffins failed to realize that ice-sheet ingestion (sliding off the wings to be ingested by both rear-mount engines) would not benefit at all from each engine hiccup causing a continual uprating of the other (and vice-versa). To be found/uncovered in a simulator you would have to be testing various pilot inadvertencies (rather than rote expected actions). Then again, don't always believe the outcomes to be seen in a simulator. They don't necessarily faithfully emulate what would happen systems-wise in an aircraft... particularly when it comes to complex materiel failure modes or illogical sequiturs (e.g. MCAS)
So, if such an untestable circumstance were to happen to a competent crew and they were to inadvertently shut-down the wrong engine (and then/were in "clean-up mode":
a. The residual hyds would break the downlocks - but not retract the gear (and it would appear to be still selected down)
b. The alternate flaps might start to retract (gear downlocks not being now "made") once selected, but the slats remain out.
c. the RAT would deploy
The point at which all thrust ceases (and the climb vector flattens/reverses) is easily seen
in the video shot from the 6:30 clock position from about a km away. It's readily apparent.
An engine failure just off the runway after V1 in a fully loaded 787-8 in high ambient temperatures would assuredly have a crew thinking about a "toute suite" shutdown of a misbehaving donk. That's human nature. When the PERF is quite sluggish you will be thinking that a quick clean-up of the situation is certainly called for. That's just human nature unfortunately, particularly when you are under the time compression of dire circumstance (and the airframe is performing like a lame dog, just due to the environmentals and the early failure). I think that what the pilot reportedly said to ATC in his Mayday bears that out as being his instant mindset (quite clearly). Been in that "fools rush in" circ myself. You just have to "sit on your hands" and fly the beast.
But then again, if the RAT was NOT found deployed, then it's a case of the right seat mistakenly sucking in the flaps and slats... and that will do it... whatever the power/TOGA might be.
https://tinyurl.com/4zzkeeud
Rotation +33s
Mayday call +44s, circa 300 ft altitude (ADS-B)
Peak altitude +49s, 625 ft (Flightradar24)
Impact +58s, crash site 1.6 km from runway
So, if such an untestable circumstance were to happen to a competent crew and they were to inadvertently shut-down the wrong engine (and then/were in "clean-up mode":
a. The residual hyds would break the downlocks - but not retract the gear (and it would appear to be still selected down)
b. The alternate flaps might start to retract (gear downlocks not being now "made") once selected, but the slats remain out.
c. the RAT would deploy
The point at which all thrust ceases (and the climb vector flattens/reverses) is easily seen
in the video shot from the 6:30 clock position from about a km away. It's readily apparent.
An engine failure just off the runway after V1 in a fully loaded 787-8 in high ambient temperatures would assuredly have a crew thinking about a "toute suite" shutdown of a misbehaving donk. That's human nature. When the PERF is quite sluggish you will be thinking that a quick clean-up of the situation is certainly called for. That's just human nature unfortunately, particularly when you are under the time compression of dire circumstance (and the airframe is performing like a lame dog, just due to the environmentals and the early failure). I think that what the pilot reportedly said to ATC in his Mayday bears that out as being his instant mindset (quite clearly). Been in that "fools rush in" circ myself. You just have to "sit on your hands" and fly the beast.
But then again, if the RAT was NOT found deployed, then it's a case of the right seat mistakenly sucking in the flaps and slats... and that will do it... whatever the power/TOGA might be.
https://tinyurl.com/4zzkeeud
Rotation +33s
Mayday call +44s, circa 300 ft altitude (ADS-B)
Peak altitude +49s, 625 ft (Flightradar24)
Impact +58s, crash site 1.6 km from runway
Last edited by bbofh; 13th June 2025 at 07:53 .
June 13, 2025, 03:02:00 GMT
permalink Post: 11899948
OK, I promised some informed speculation when I got back, so here goes:
Disclaimer: never worked the 787, so my detailed knowledge is a bit lacking.
First off, this is perplexing - especially if the RAT was deployed. There is no 'simple' explanation that I can come up with.
GEnx-1B engines have been exceptionally reliable, and the GE carbon composite fan blades are very robust and resistant to bird strike damage (about 15 years after the GE90 entry into service, I remember a GE boast that no GE90 (carbon composite) fan blades had needed to be scrapped due to damage (birdstrike, FOD, etc. - now that was roughly another 15 years ago, so is probably no longer true, but it shows just how robust the carbon composite blades are - far better than the more conventional titanium fan blades).
Not saying it wasn't somehow birdstrike related, just that is very unlikely (then again, all the other explanations I can come up with are also very unlikely
).
Using improper temp when calculating TO performance - after some near misses, Boeing added logic that cross-compares multiple total temp probes - aircraft TAT (I think the 787 uses a single, dual element probe for aircraft TAT, but stand to be corrected) and the temp measured by the engine inlet probes - and puts up a message if they disagree by more than a few degree tolerance - so very, very unlikely.
N1 power setting is somewhat less prone to measurement and power setting errors than EPR (N1 is a much simpler measurement than Rolls EPR) - although even with EPR, problems on both engines at the same time is almost unheard of.
The Auto Thrust (autothrottle) function 'falls asleep' at 60 knots - and doesn't unlock until one of several things happens - 250 knots, a set altitude AGL is exceeded (I'm thinking 3,000 ft. but the memory is fuzzy), thrust levers are moved more than a couple of degrees, or the mode select is changed (memory says that last one is inhibited below 400 ft. AGL). So an Auto Thrust malfunction is also extremely unlikely. Further, a premature thrust lever retard would not explain a RAT deployment.
TO does seem to be very late in the takeoff role - even with a big derate, you still must accelerate fast enough to reach V1 with enough runway to stop - so there is still considerable margin if both engines are operating normally. That makes me wonder if they had the correct TO power setting - but I'm at a loss to explain how they could have fouled that up with all the protections that the 787 puts on that.
If one engine did fail after V1, it's conceivable that they shut down the wrong engine - but since this happened literally seconds after takeoff, it begs the question why they would be in a big hurry to shut down the engine. Short of an engine fire, there is nothing about an engine failure that requires quick action to shut it down - no evidence of an engine fire, and even with an engine fire, you normally have minutes to take action - not seconds.
The one thing I keep thinking about is someone placing both fuel switches to cutoff immediately after TO. Yes, it's happened before (twice - 767s in the early 1980s), but the root causes of that mistake are understood and have been corrected. Hard to explain how it could happen (unless, God forbid, it was intentional).
Disclaimer: never worked the 787, so my detailed knowledge is a bit lacking.
First off, this is perplexing - especially if the RAT was deployed. There is no 'simple' explanation that I can come up with.
GEnx-1B engines have been exceptionally reliable, and the GE carbon composite fan blades are very robust and resistant to bird strike damage (about 15 years after the GE90 entry into service, I remember a GE boast that no GE90 (carbon composite) fan blades had needed to be scrapped due to damage (birdstrike, FOD, etc. - now that was roughly another 15 years ago, so is probably no longer true, but it shows just how robust the carbon composite blades are - far better than the more conventional titanium fan blades).
Not saying it wasn't somehow birdstrike related, just that is very unlikely (then again, all the other explanations I can come up with are also very unlikely
).
Using improper temp when calculating TO performance - after some near misses, Boeing added logic that cross-compares multiple total temp probes - aircraft TAT (I think the 787 uses a single, dual element probe for aircraft TAT, but stand to be corrected) and the temp measured by the engine inlet probes - and puts up a message if they disagree by more than a few degree tolerance - so very, very unlikely.
N1 power setting is somewhat less prone to measurement and power setting errors than EPR (N1 is a much simpler measurement than Rolls EPR) - although even with EPR, problems on both engines at the same time is almost unheard of.
The Auto Thrust (autothrottle) function 'falls asleep' at 60 knots - and doesn't unlock until one of several things happens - 250 knots, a set altitude AGL is exceeded (I'm thinking 3,000 ft. but the memory is fuzzy), thrust levers are moved more than a couple of degrees, or the mode select is changed (memory says that last one is inhibited below 400 ft. AGL). So an Auto Thrust malfunction is also extremely unlikely. Further, a premature thrust lever retard would not explain a RAT deployment.
TO does seem to be very late in the takeoff role - even with a big derate, you still must accelerate fast enough to reach V1 with enough runway to stop - so there is still considerable margin if both engines are operating normally. That makes me wonder if they had the correct TO power setting - but I'm at a loss to explain how they could have fouled that up with all the protections that the 787 puts on that.
If one engine did fail after V1, it's conceivable that they shut down the wrong engine - but since this happened literally seconds after takeoff, it begs the question why they would be in a big hurry to shut down the engine. Short of an engine fire, there is nothing about an engine failure that requires quick action to shut it down - no evidence of an engine fire, and even with an engine fire, you normally have minutes to take action - not seconds.
The one thing I keep thinking about is someone placing both fuel switches to cutoff immediately after TO. Yes, it's happened before (twice - 767s in the early 1980s), but the root causes of that mistake are understood and have been corrected. Hard to explain how it could happen (unless, God forbid, it was intentional).
Very hot day, so far past breakpoint, N1 Max sensitive to TAT. Any TAT or DT latching (can't recall if) would be cleared - if at 400 ft AGL, which may not have been attained here.
June 13, 2025, 05:15:00 GMT
permalink Post: 11900008
Just as an example of how many misconceptions, mistruths, half truths and complete BS there is in this, and any accident, thread consider this\x85
I am very sure the only variant of the 757/767 that had a RAT was the 767-400, which was not in production in 1986. I flew the 767-200 and -300 with 3 different engine combinations (around 30-40 different airframes and 2 airlines) and none of them had a RAT.
Happy to be corrected if this model 757 (or 767 as someone in a later post says) had a RAT.
I am very sure the only variant of the 757/767 that had a RAT was the 767-400, which was not in production in 1986. I flew the 767-200 and -300 with 3 different engine combinations (around 30-40 different airframes and 2 airlines) and none of them had a RAT.
Happy to be corrected if this model 757 (or 767 as someone in a later post says) had a RAT.
June 13, 2025, 06:15:00 GMT
permalink Post: 11900048
I tend to agree. I taught ground school for the 744, 748, 777, 320 and 330. I used to tell my students the most critical phase of flight is the 3 minutes after 100 knots. That\x92s when critical TO inhibits occur and ADP\x92s (777) come online etc etc. But the elephant in the room for me is thrust reduction. On the Boeing it can be an altitude or a flap setting where the AT will reduce thrust from derated TO to CLB. For the Bus it\x92s an altitude and the crew are prompted to move the TL\x92s to the CLB detent. If at positive rate (or climb) the PM selected one or two units of flap up instead of gear up would the thrust reduction explain the aircraft\x92s response? This would startle any PF and he wouldn\x92t (muscle memory) manually move the levers back to TOGA while trying to follow the FD Bars to maintain V2 and RWY heading.
If the RAT deployment is indeed confirmed then my theory is out the window\x85.
If the RAT deployment is indeed confirmed then my theory is out the window\x85.
June 13, 2025, 06:24:00 GMT
permalink Post: 11900055
Just as an example of how many misconceptions, mistruths, half truths and complete BS there is in this, and any accident, thread consider this\x85
I am very sure the only variant of the 757/767 that had a RAT was the 767-400, which was not in production in 1986. I flew the 767-200 and -300 with 3 different engine combinations (around 30-40 different airframes and 2 airlines) and none of them had a RAT.
Happy to be corrected if this model 757 (or 767 as someone in a later post says) had a RAT.
I am very sure the only variant of the 757/767 that had a RAT was the 767-400, which was not in production in 1986. I flew the 767-200 and -300 with 3 different engine combinations (around 30-40 different airframes and 2 airlines) and none of them had a RAT.
Happy to be corrected if this model 757 (or 767 as someone in a later post says) had a RAT.
That was the case where the plane ran out of fuel midflight due to miscalculations of metric/imperial and volume weights of fuel being loaded. The RAT deployed and they glided to land at the decommissioned Gimli airfield.
June 13, 2025, 06:42:00 GMT
permalink Post: 11900067
Such a terrible shame, condolences to all. It looks inexplicable from the CCTV.
Seems time for a visual evidence review.
There seems to be a RAT theory based on a hyper zoomed artifact and someone showing a RAT deployed on a different airframe. Not convinced about that, you might get a similar artifact from a belly antenna. The noise? CCTV doesn\x92t have noise and the other pictures I saw were from a car in traffic.
Others are are saying it climbed to 500\x92, not sure about that, the highest I have seen visually is less than 300\x92, QNH vs. QFE I suspect.
Flaps vs. Gear definitely a possibility and the AoA was increasing particularly after the descent started.
Double EF (If RAT deployment not a red herring) Fuel contamination? Would have to be deliberate as no other aircraft affected, unlikely. Maintenance or crew error, possible unlikely. Bird strike, no evidence.
MTOW error possible but it seemed to take off fine so no reason for the return to the ground.
What about the bang the survivor heard? I suspect you can treat the evidence of anyone involved in an air crash with a pinch of salt. Order of events are often out of sequence even when talking to trained observers in less stressful situations
MCP mis-setting to 100\x92. Engage AP early, often seen, thrust immediately commands to idle by ATHR, starts to sink, extreme startle and forget gear because it appears like a double EF.
I know where my money is but only time will tell, if they get the Black Boxes in good condition, the factual statement should clear it up quickly.
Seems time for a visual evidence review.
There seems to be a RAT theory based on a hyper zoomed artifact and someone showing a RAT deployed on a different airframe. Not convinced about that, you might get a similar artifact from a belly antenna. The noise? CCTV doesn\x92t have noise and the other pictures I saw were from a car in traffic.
Others are are saying it climbed to 500\x92, not sure about that, the highest I have seen visually is less than 300\x92, QNH vs. QFE I suspect.
Flaps vs. Gear definitely a possibility and the AoA was increasing particularly after the descent started.
Double EF (If RAT deployment not a red herring) Fuel contamination? Would have to be deliberate as no other aircraft affected, unlikely. Maintenance or crew error, possible unlikely. Bird strike, no evidence.
MTOW error possible but it seemed to take off fine so no reason for the return to the ground.
What about the bang the survivor heard? I suspect you can treat the evidence of anyone involved in an air crash with a pinch of salt. Order of events are often out of sequence even when talking to trained observers in less stressful situations
MCP mis-setting to 100\x92. Engage AP early, often seen, thrust immediately commands to idle by ATHR, starts to sink, extreme startle and forget gear because it appears like a double EF.
I know where my money is but only time will tell, if they get the Black Boxes in good condition, the factual statement should clear it up quickly.
Last edited by Bluffontheriver123; 13th June 2025 at 07:05 . Reason: Emphasis
June 13, 2025, 06:43:00 GMT
permalink Post: 11900068
If it is true that the RAT deployed during the flight, possibly from early on in the 30s of airborne time, and multiple independent pieces of evidence suggest that this is the case, then that narrows down things considerably. Double engine failure, massive electrical issues or fuel control switches / fire switches on both engines are all I can think of that could cause this. Gear/flaps etc. are a red herring. During the period after the power loss and before the RAT came online (up to 8s
AFAIK
), almost everything would have been load shed as battery power only.
June 13, 2025, 07:00:00 GMT
permalink Post: 11900081
Such a terrible shame, condolences to all. It looks inexplicable from the CCTV.
Seems time for a visual evidence review.
There seems to be a RAT theory based on a hyper zoomed artifact and someone showing a RAT deployed on a different airframe. Not convinced about that, you might get a similar artifact from a belly antenna. The noise? CCTV doesn\x92t have noise and the other pictures I saw were from a car in traffic.
Others are are saying it climbed to 500\x92, not sure about that, the highest I have seen visually is less than 300\x92, QNH vs. QFE I suspect.
Flaps vs. Gear definitely a possibility and the AoA was increasing but only after the descent started.
Double EF (If RAT deployment not a red herring) Fuel contamination? Would have to be deliberate as no other aircraft affected, unlikely. Maintenance or crew error, possible unlikely. Bird strike, no evidence.
MTOW error possible but it seemed to take off fine so no reason for the return to the ground.
What about the bang the survivor heard? I suspect you can treat the evidence of anyone involved in an air crash with a pinch of salt. Order of events are often out of sequence even when talking to trained observers in less stressful situations
MCP mis-setting to 100\x92. Engage AP early, often seen, thrust immediately commands to idle by ATHR, starts to sink, extreme startle and forget gear because it appears like a double EF.
I know where my money is but only time will tell, if they get the Black Boxes in good condition, the factual statement should clear it up quickly.
Seems time for a visual evidence review.
There seems to be a RAT theory based on a hyper zoomed artifact and someone showing a RAT deployed on a different airframe. Not convinced about that, you might get a similar artifact from a belly antenna. The noise? CCTV doesn\x92t have noise and the other pictures I saw were from a car in traffic.
Others are are saying it climbed to 500\x92, not sure about that, the highest I have seen visually is less than 300\x92, QNH vs. QFE I suspect.
Flaps vs. Gear definitely a possibility and the AoA was increasing but only after the descent started.
Double EF (If RAT deployment not a red herring) Fuel contamination? Would have to be deliberate as no other aircraft affected, unlikely. Maintenance or crew error, possible unlikely. Bird strike, no evidence.
MTOW error possible but it seemed to take off fine so no reason for the return to the ground.
What about the bang the survivor heard? I suspect you can treat the evidence of anyone involved in an air crash with a pinch of salt. Order of events are often out of sequence even when talking to trained observers in less stressful situations
MCP mis-setting to 100\x92. Engage AP early, often seen, thrust immediately commands to idle by ATHR, starts to sink, extreme startle and forget gear because it appears like a double EF.
I know where my money is but only time will tell, if they get the Black Boxes in good condition, the factual statement should clear it up quickly.
June 13, 2025, 07:24:00 GMT
permalink Post: 11900099
My theory on this is a wrong weight/temperature entry, too much derating, attempted take-off in too low an energy state and subsequent departure stall.
From the airport cam video, the aircraft seems to stick off just at the end of the runway.
Both engines are working at full blast until at least obstacle clearance height, they kick up unusual amounts of dust for a take-off.
Theoretical sequence of events:
1. Pilots entered the wrong take off perf data
2. During the take-off roll they realize that the aircraft isn't picking up enough speed but too late to reject and firewall the throttles
3. They use up the whole runway and get the aircraft off the ground in ground effect
4. Ground effect ends and they fail to maintain a positive rate of climb, hence gears stay down
5. Aircraft stalls and sinks into the ground
Textbook departure stall and failure to pitch down to recover from it.
From the airport cam video, the aircraft seems to stick off just at the end of the runway.
Both engines are working at full blast until at least obstacle clearance height, they kick up unusual amounts of dust for a take-off.
Theoretical sequence of events:
1. Pilots entered the wrong take off perf data
2. During the take-off roll they realize that the aircraft isn't picking up enough speed but too late to reject and firewall the throttles
3. They use up the whole runway and get the aircraft off the ground in ground effect
4. Ground effect ends and they fail to maintain a positive rate of climb, hence gears stay down
5. Aircraft stalls and sinks into the ground
Textbook departure stall and failure to pitch down to recover from it.