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FullWings
2025-06-12T12:12:00 permalink Post: 11899143 |
How horrible. From what has surfaced so far, it does appear that the aircraft became airborne and got to a reasonable height and groundspeed, within parameters for a normal takeoff. The video with RAT-like audio and the snapshot from another video showing hints of RAT deployment seem to be the biggest clues so far: flaps and gear are a minor issue compared with a serious power loss, although loss of electrical power would trigger the RAT if it uses the same logic on the 787 as earlier Boeings.
That you can hear the RAT on the video over what should be engines at takeoff thrust at that point adds credence to the theory, as does reports of a MAYDAY. Subjects: Mayday Parameters RAT (All) RAT (Deployment) |
FullWings
2025-06-13T06:43:00 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.
Subjects: Dual Engine Failure Engine Failure (All) Fuel (All) Fuel Cutoff RAT (All) RAT (Deployment) 3 users liked this post. |
FullWings
2025-06-13T07:36:00 permalink Post: 11900111 |
People on here seem convinced the RAT was deployed because they\x92ve seen it/heard it so many times before. They may be right. But if they are, then it means the RAT has deployed countless times before without both engines having failed, so it doesn\x92t definitively tell us anything.
System-wide electrical issues Double engine failure Selection of fuel switch and/or fire switch on both engines Any speculation about gear, flap, runway, etc. is redundant if the RAT did auto-deploy as it points to a very serious technical issue with the airframe rather than what was done with thrust levers or what the pilots had for breakfast. I haven\x92t seen what the 787 cockpit looks like on battery power only but on the 777 it gets pretty dark with only the essential P1 instruments and VHF1 available until the RAT comes online, which is a measurable amount of time after deployment is triggered. Subjects: Dual Engine Failure Engine Failure (All) Engine Shutdown Fuel (All) Fuel Cutoff RAT (All) RAT (Deployment) 2 users liked this post. |
FullWings
2025-06-14T07:18:00 permalink Post: 11901188 |
A summary of the more certain things we know about the accident so far:
The takeoff run was from the full length and appeared normal, even after comparing with the same flight on previous days. This very much reduces the likelihood of it being a performance issue, e.g. wrong flaps, derate, ZFW/TOW, etc. Shortly after takeoff, the gear started retracting but stopped in an early intermediate position. At the same time the aircraft climb rate dropped off, then it started a shallow descent. This is consistent with a loss of electrical power causing a loss of hydraulic pressure and total engine thrust from both engines reducing below that generated by one engine at the takeoff setting. The position reporting also went offline at that moment, indicating that it was likely load shed due to an electrical malfunction. What exactly caused the engine/electrical issues remains speculative. An action slip mistaking flaps for gear seems much less likely as due to the above, the correct selection was probably made. From the videos of the last moments, there is strong evidence that the RAT was deployed, which has a very short list of possible triggers. The sole eye witness from inside describes power issues which lends credence. Taken together, it seems that there was an event (or events) shortly after rotation that compromised both engines and the electrical system. There is no evidence yet of birdstrikes and continued engine operation *should* not be affected by the aircraft electrical system as they are independently/internally powered, so logic would have the engines failing first leading to a cascade of other problems. Something that affects all engines pretty much simultaneously is a rare beast but it has happened in the past; outside of a deliberate selection of the fuel and/or fire switches for both power plants there is fuel contamination, FOD and not much else. Its seems at least one FDR has been recovered so depending on where they take it for read-out, we should get some initial facts fairly shortly. Subjects: FDR Fuel (All) Fuel Contamination Hydraulic Failure (All) Hydraulic Pumps RAT (All) RAT (Deployment) 14 users liked this post. |
FullWings
2025-06-14T07:36:00 permalink Post: 11901205 |
Only on the electrically-powered centre system (which does gear and flaps). Left and right have engine-driven pumps which will provide plenty of power for flight controls provided the engines remain above maybe 30-40% N2.
Compromising both engines inherently compromises the electrical system: dropping below idle N2 (plus some safety margin) disconnects generators. Subjects: Flaps (All) Flaps vs Gear Generators/Alternators RAT (All) 3 users liked this post. |
FullWings
2025-06-14T08:09:00 permalink Post: 11901235 |
hello guys,
I'm pilot but not on a heavy one, so I may have a naive question but eh..;depends on planes right ? -let's imagine, the PM raise the flaps instead of gear (on 787). Is it really a big issue that could lead to a lose of 200/300 feet ? I mean, you still have take of power ar at least climb power right ? sure you decrease the lift by raising the flaps (at constant speed though ) and lose some height, but the plane keep accelerating ,? Subjects: Flaps (All) Flaps vs Gear V1 V2 |
FullWings
2025-06-14T16:33:00 permalink Post: 11901629 |
Subjects: DFDR |
FullWings
2025-06-14T21:17:00 permalink Post: 11901843 |
Subjects: RAT (All) RAT (Deployment) 1 user liked this post. |
FullWings
2025-06-14T22:21:00 permalink Post: 11901900 |
I think it needs to be said again that pretty much anything can happen to the aircraft systems and the engines will carry on running - this is by design as they have independent FADEC and power supplies and at sea level fuel will get through without boost pumps. You could almost saw the wing off the fuselage and the engine would still produce thrust, TCMA notwithstanding.
We don\x92t know yet what actually triggered the RAT from the relatively short list but every item on it means there is a serious/critical failure(s). The flight path suggests that it was a double engine failure or shutdown (commanded or uncommanded) as anything else should have left the aeroplane in a poor state but able to climb away. Subjects: Dual Engine Failure Engine Failure (All) FADEC Fuel (All) Fuel Pumps RAT (All) TCMA (All) 6 users liked this post. |
FullWings
2025-06-16T00:05:00 permalink Post: 11902993 |
OK, technical questions for those who might know the answers: I think many on this thread are expecting the DFDR data to give clear answers to what happened to this flight, but due to the likely electrical power loss, what would actually have been recorded?
AFAIK
the 787 DFDRs have an internal battery but if the power is off to the rest of the aeroplane, what data, if any, is going to make its way to the units? Is anything recorded while on battery power? Does the RAT coming online after a pause restore some of the recording functionality?
1 user liked this post. |
FullWings
2025-06-16T09:47:00 permalink Post: 11903332 |
a) It might be damaged and they are going to need to use forensic techniques to recover the data. This can take time. b) They could have read it out but due to lack of power to the rest of the aircraft and associated sensors at the time, it hasn\x92t recorded very much, like in the Jeju crash, so the investigation continues. Subjects: EAFR 3 users liked this post. |
FullWings
2025-06-18T08:46:00 permalink Post: 11905031 |
Most? The Airbus I'm familiar with is 100' AGL or 5s after liftoff and I think this is common to all Airbus FBW. The B787 & B777 appear to be 200' AGL but I'm taking this from online FCOM extracts. The
B737
does appear to be 400'. Company limitations may be higher.
As mentioned elsewhere both EK and Air NZ have had messy low level mis-set altitude capture incidents with the B777, but in isolation, obviously, this wouldn't cause RAT extension. About airport cameras. Someone pointed out on the other thread that airports have more coverage than they would necessarily advertise. Presumably available to investigators but not to the public or press. The ideas of mis-set MCP, AT modes, etc. were worth exploring but by this point, like the gear/flap/performance ones, there is enough convincing evidence now that a) the takeoff was normal until it suddenly wasn\x92t and b) none of the above would cause RAT deployment and a glide into the ground. Subjects: FBW FCOM RAT (All) RAT (Deployment) 3 users liked this post. |
FullWings
2025-06-18T09:22:00 permalink Post: 11905053 |
That\x92s interesting and different from the 777 logic. Have you actually tried this in the sim or otherwise?
Subjects: None |
FullWings
2025-06-18T10:26:00 permalink Post: 11905114 |
Subjects: V1 |
FullWings
2025-06-18T13:12:00 permalink Post: 11905236 |
Given that there are >1,100 787s in service, you would be losing a significant part of the World\x92s air transport infrastructure if you grounded them. Also, if you\x92re still nowhere near understanding what caused it, how would you \x93unground\x94 the fleet if you don\x92t get answers for some time? It\x92s obviously something rare/unique, given the 14 years of operation without such an accident, so statistics should be on your side if you did nothing until you had more surety as to where the problem(s) lay? Subjects: Fuel (All) Fuel Contamination 4 users liked this post. |
FullWings
2025-06-19T08:44:00 permalink Post: 11905837 |
Thank god someone has pointed out the absolute cobblers some people who claim to have some experience of this type (and other completely unrelated types) have been spouting. And if anyone else wants to erroneously compare the 757/767 low level EPR ALT CAP scenario , that keeps the TO thrust on, it doesn\x92t reduce it! This is truely one of the worst of these accidents threads I\x92ve read in a long time, I pity the mods.
Subjects: RAT (All) RAT (Deployment) 2 users liked this post. |
FullWings
2025-06-20T09:43:00 permalink Post: 11906781 |
Although it seems inconceivable that they did not firewall the thrust levers, it will be interesting to know if and when this happened. The aircraft clearly did not have enough thrust for the flight regime with the gear extended etc. But does this imply a total loss of thrust on both engines?
I would be very surprised if the thrust levers were not firewalled early on, in fact with such determination that they went through the instrument panel! On a wider observation, professional commercial pilots like the Air India ones in this accident go through regular simulator training according their own SOPs, which when dealing with things like thrust loss during or after the takeoff roll are likely pretty similar or even identical to the manufacturer\x92s guidelines; if they did differ it would be because they were more conservative in application. Boeing standard is to do nothing until 200\x92AGL other than control the aircraft in yaw, pitch and roll. Above 400\x92AGL you can start doing some drills, if applicable. This assumes, of course, that you can get to these heights in the first place. I would put forward that in this accident, the crew immediately found themselves in what Boeing call \x93Special situations\x94 or \x93Situations beyond the scope of normal procedures\x94. We don\x92t know yet whether there was a thrust loss or total failure at the outset; we don\x92t know if the RAT deployed due to sensed failures or control operation. As a trainer, the captain would have known the implications of actioning the dual engine failure memory items, especially near the ground, but if you\x92ve tried everything else and are still going down then what is there to lose? This is not to suggest this is what happened, just to fill in the blanks in terms of possibilities. Whatever did occur likely put them outside the realm of SOPs in short order, which is a difficult situation at the best of times, especially as for your whole flying career you have been trained and assessed at your ability to conform to those SOPs as accurately as possible in the takeoff phase. Subjects: Dual Engine Failure Engine Failure (All) Generators/Alternators Hydraulic Failure (All) Hydraulic Pumps RAT (All) RAT (Deployment) Takeoff Roll 9 users liked this post. |
FullWings
2025-06-21T07:19:00 permalink Post: 11907541 |
The possibility that one engine failure occurred at a critical point in the take off and that possibly the wrong engine fuel cutoff switch was pulled.
Where the meme has come from that jet pilots have to shut down engines as quickly as possible I don\x92t know but it is incorrect. If you left a failed engine without securing it for 5 minutes, little to no harm would come of it. Even if it was on fire (which is not necessarily flames, just higher than normal temperatures inside the nacelle) they are certified to be in this condition for some considerable time before it becomes a problem. Yes, I think the phrase \x93without undue delay\x94 could be used for a fire indication but that\x92s a minimum of 400\x92AGL in Boeings and does not absolve you of all the cross-checking and CRM that should happen with an engine shutdown. This is practiced/checked at the least every 6 months in EASA land and any attempt to rush a shutdown at low level would lead to a debrief and more training/checking. To put it this way, control of the aeroplane and lateral/vertical navigation is far more important than doing stuff with a failed power plant. Something like an ET should be absolutely prioritised over engine drills. Subjects: Engine Failure (All) Engine Shutdown Fuel (All) Fuel Cutoff Wrong Engine 8 users liked this post. |
FullWings
2025-06-22T19:59:00 permalink Post: 11908793 |
Subjects: None 5 users liked this post. |
FullWings
2025-07-01T06:45:00 permalink Post: 11914044 |
Perhaps a result of being too dense, in these threads I have not understood whatsoever the discussions on L/D, best glide, AOA, stall speed, angles, whatever, as being relevant to this flight. I assume that the pilot flying was flying, i.e. stick and rudder. I give him/her the benefit of the doubt on account of being a pilot. Professional or not.
The real question is why this happened when engines and their associated systems are, by design and regulation, as independent as possible. The top runners at the moment are (in no particular order): pilot action, simultaneous hardware/software malfunction and massive fuel contamination. They are all very unlikely (and cogent technical arguments can be made against each of them) but so is the event that followed. Subjects: ADSB Fuel (All) Fuel Contamination Lift/Drag Ratio |
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