2025-06-13T06:15:00
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.
Subjects: Flap Setting Flaps (All) RAT (All) RAT (Deployment) TOGA V2
2 users liked this post.
2025-06-13T06:43:00
permalink Post: 11900069
You are quite correct. Every wide body Boeing (and Airbus) twin plus the 747-8 has a RAT - Some drive a generator and/or some drive a hydraulic pump. The reason for the 748 having a RAT is that for a 3 or more engine flameout (Boeing speak for a 4 engine flameout) the EDP’s are depressurised to unload the gearbox for ease of windmilling. Hence, no engines = no hydraulics. Edited to clarify the different reasons for the RAT. Edited to add every “wide body”
Last edited by aeo; 13th Jun 2025 at 08:04 .
Subjects: Generators/Alternators Hydraulic Failure (All) Hydraulic Pumps RAT (All)
2025-06-13T07:00:00
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.
Subjects: Bird Strike CCTV Condolences Fuel (All) Fuel Contamination RAT (All) RAT (Deployment) V2 VNAV
1 user liked this post.
2025-06-13T08:02:00
permalink Post: 11900133
Subjects: None
2025-06-14T14:05:00
permalink Post: 11901513
I agree it is helpful to seek a consensus on some of these matters.
The most productive responses would be along the lines of:-
(1) I too have read all previous posts and agree that your summary reflects the current consensus,
(2) I too have read all previous posts and agree your summary reflects the consensus HOWEVER I challenge that consensus because... [ [i]EITHER (a) reference to previous post that merits greater credence, OR (b) new evidence supplied],
(3) I too have read all previous posts but I do NOT agree your summary reflects the consensus [explanation required].
It is not necessary for everyone who thinks (1) to say it (although some initial feedback would be useful!). However, if any of the more experienced and informed PPRuNers are thinking either (2) or (3) then it would be instructive to hear that.
FWIW, yours strikes me as a reasonable summary of the best consensus I have been able to discern (as of ~30 minutes ago). There are multiple caveats to each line item, but I presume you've deliberately left those out for the sake of readability, so I'll do the same!
The only comments I would add are:-
- It's a stretch to say the RAT is seen or heard "conclusively". Doubts have been expressed about the video quality and there are dissenting views regarding the audio. If a few more people were able to wade in on the audio point in particular, this could be very beneficial in moving the discussion forward because the presence or otherwise of the RAT is significant to several competing theories.
- On the subject of audio, I am surprised there has not been more discussion regarding engine noise. In the primary eye witness video the (alleged) RAT can be heard distinctly, as can the sounds of distant impact. If the engines were working as expected when overflying the camera and then flying directly away from it, do we really not think the engine noise would be more conclusive, i.e. louder (notwithstanding quiet engines and derated takeoffs)?
Whichever way readers are leaning in the flaps versus power loss debate, surely these two points are pivotal, and we have actual evidence available to discuss?
- Gear bogies: I'm not sure a consensus has yet been reached regarding the angle of the bogies. (I am not personally qualified to comment on this - I am purely saying I don't see a clear consensus just yet among those who are)
- Mayday call: I don't recall seeing a confirmed source for the widely reported mayday. Others have brought this up in the thread but nobody appears to be able to confirm one way or the other. If accurate, its contents are informative. Am I right to presume that you have left it out of your summary due to a lack of confirmation?
The most productive responses would be along the lines of:-
(1) I too have read all previous posts and agree that your summary reflects the current consensus,
(2) I too have read all previous posts and agree your summary reflects the consensus HOWEVER I challenge that consensus because... [ [i]EITHER (a) reference to previous post that merits greater credence, OR (b) new evidence supplied],
(3) I too have read all previous posts but I do NOT agree your summary reflects the consensus [explanation required].
It is not necessary for everyone who thinks (1) to say it (although some initial feedback would be useful!). However, if any of the more experienced and informed PPRuNers are thinking either (2) or (3) then it would be instructive to hear that.
FWIW, yours strikes me as a reasonable summary of the best consensus I have been able to discern (as of ~30 minutes ago). There are multiple caveats to each line item, but I presume you've deliberately left those out for the sake of readability, so I'll do the same!
The only comments I would add are:-
- It's a stretch to say the RAT is seen or heard "conclusively". Doubts have been expressed about the video quality and there are dissenting views regarding the audio. If a few more people were able to wade in on the audio point in particular, this could be very beneficial in moving the discussion forward because the presence or otherwise of the RAT is significant to several competing theories.
- On the subject of audio, I am surprised there has not been more discussion regarding engine noise. In the primary eye witness video the (alleged) RAT can be heard distinctly, as can the sounds of distant impact. If the engines were working as expected when overflying the camera and then flying directly away from it, do we really not think the engine noise would be more conclusive, i.e. louder (notwithstanding quiet engines and derated takeoffs)?
Whichever way readers are leaning in the flaps versus power loss debate, surely these two points are pivotal, and we have actual evidence available to discuss?
- Gear bogies: I'm not sure a consensus has yet been reached regarding the angle of the bogies. (I am not personally qualified to comment on this - I am purely saying I don't see a clear consensus just yet among those who are)
- Mayday call: I don't recall seeing a confirmed source for the widely reported mayday. Others have brought this up in the thread but nobody appears to be able to confirm one way or the other. If accurate, its contents are informative. Am I right to presume that you have left it out of your summary due to a lack of confirmation?
- The bogie could be explained by the Flap/Slat priority valve giving priority to the flaps if the PM suddenly realised his mistake and quickly put the flap lever back to the TO position and then selected the gear lever to UP. Those systems are both heavy hitters and would\x92ve sucked the life out of the CTR hydraulic system pumps.
- There is no way loss of AC (alleged RAT deployment) could've caused a spool down of both engines. Think QF A380 incident in SIN - The entire #1 engine wiring harness in the wing was completely severed and yet it continued (by design) to run at its previous thrust setting. They had to shut it down using a fire truck!
- History and design would dictate that a big 180 minutes ETOP\x92s twin such as the 787 having a dual engine failure or significant power loss at such a critical phase of flight would be a billion to one chance at best. Only the Airbus A400 had a software issue causing all 4 engine fuel shutoff valves to close causing it to crash killing the flight test crew - But this was during its development and flt testing.
- Wide body twin\x92s delivering in the region of 60,000 to 115,000 lbs of thrust at TO rarely , if at all, flame out from multiple bird strike(s) like the baby Bus\x92s and Boeing\x92s. If anyone has seen the frozen chickens at TO power video would know what I\x92m talking about. And the Fan Blade being \x91blown off\x92 as well. In both cases the engine was was able to maintain full TOGA thrust for significantly longer than the AI aircraft.
But it\x92s early days and anything could happen. And nothing surprises me anymore.
Subjects: Bird Strike Dual Engine Failure Engine Failure (All) Flap Retraction Flaps (All) Gear Retraction Hydraulic Failure (All) Hydraulic Pumps Mayday RAT (All) RAT (Deployment) TOGA
3 users liked this post.
2025-06-14T14:15:00
permalink Post: 11901520
Subjects: None
2025-06-14T15:35:00
permalink Post: 11901582
What concerns me a little bit is if indeed AC power is lost, would the suction feed inlets in the wing tanks provide enough fuel flow to maintain TO thrust?
I know the system is designed to achieve this in a situation where all of the AC powered boost pumps are lost. But what about in a real situation...
Could this cause a degradation of thrust? Even the slightest decrease..
And if the Captain(?) mentioned power loss in his Mayday. Was he referring to electrical power loss?
I know the system is designed to achieve this in a situation where all of the AC powered boost pumps are lost. But what about in a real situation...
Could this cause a degradation of thrust? Even the slightest decrease..
And if the Captain(?) mentioned power loss in his Mayday. Was he referring to electrical power loss?
Subjects: Fuel (All) Fuel Pumps Mayday
2025-06-14T16:02:00
permalink Post: 11901606
Once the fuel LP and HP Shutoff valves are open, they stay there until commanded otherwise so an AC power failure will have no affect. They will remain in the last position at the time of the loss. They will then be on suction feed which, by design, should enable the engines to maintain their selected thrust level. They ‘should’ not suffer any loss of thrust.
Edit note: the engines have their own engine driven fuel pumps which can deliver anywhere up to and above 1,100 psi.
Subjects: Fuel (All) Fuel Pump (Engine Driven) Fuel Pumps
1 user liked this post.
2025-06-14T17:01:00
permalink Post: 11901660
Fair point Pip.
I just saw a picture of the tail (taken from above) and the APU door is partially open?
I believe the 787 has a similar APU automatic start function with loss of AC power just like the 777. It looks like the APU door was starting to open to allow for an auto start.. Similar situation to that BA 777 that landed short in LHR due to fuel icing.
Its looking more and more like an AC power loss.
Interestingly, the DGAC order for AI maintenance to check those random 787 systems are all associated in some way to an automatic RAT deployment.
I just saw a picture of the tail (taken from above) and the APU door is partially open?
I believe the 787 has a similar APU automatic start function with loss of AC power just like the 777. It looks like the APU door was starting to open to allow for an auto start.. Similar situation to that BA 777 that landed short in LHR due to fuel icing.
Its looking more and more like an AC power loss.
Interestingly, the DGAC order for AI maintenance to check those random 787 systems are all associated in some way to an automatic RAT deployment.
Subjects: APU RAT (All) RAT (Deployment)
5 users liked this post.
2025-06-14T17:07:00
permalink Post: 11901664
Subjects: APU
2025-06-15T01:21:00
permalink Post: 11902026
I can buy the AC power loss, but TCMA activation as well - That\x92s a stretch. TCMA is available on the ground and on approach and will activate if the engine thrust doesn\x92t follow the Thrust Lever command. On the ground it will shut the engine down (think RTO with engine stuck at T/O). On approach it will reduce the thrust if the engine doesn\x92t respond to the Thrust Lever command ala Cathay Pacific A330 (CMB - HKG) with the fuel contamination incident.
Subjects: Fuel (All) Fuel Contamination RAT (All) TCMA (Activation) TCMA (Air-ground Logic) TCMA (All)
5 users liked this post.
2025-06-15T02:40:00
permalink Post: 11902061
That APU door is clearly open (inflight position) indicating an autostart sequence had commenced which would only occur for a loss of all AC Busses
APU door open in the inflight position
APU door open in the inflight position
Last edited by aeo; 15th Jun 2025 at 02:43 . Reason: Remove duplication
Subjects: APU
3 users liked this post.
2025-06-15T02:46:00
permalink Post: 11902063
I thought that too JF but it’s held down by a very robust actuator.
Subjects: None
1 user liked this post.