Posts by user "FullWings" [Posts: 20 Total up-votes: 64 Pages: 1]

FullWings
2025-06-12T12:12:00
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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
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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)

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FullWings
2025-06-13T07:36:00
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Post: 11900111
Originally Posted by m0nkfish
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.
As has already been pointed out, these deployments were deliberate for test purposes and the approaches were done into airfields used by manufacturers for trials. Unless the Air India crew thought it would be fun to see what happened if they deployed the RAT shortly after takeoff, we are looking at something triggered by one or more of:

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)

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FullWings
2025-06-14T07:18:00
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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
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Post: 11901205
Originally Posted by Someone Somewhere
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.
That was included to discount the possibility that it was an autothrottle failure or some kind of mode issue - none of these would cause the engines to go sub-idle/fail, leaving the busses unpowered and triggering the RAT. Only a deliberate action or something affecting both power plants at the same time would cause what appears to have happened, so that seems to be the area where most speculation is required?

Subjects: Flaps (All)  Flaps vs Gear  Generators/Alternators  RAT (All)

3 users liked this post.

FullWings
2025-06-14T08:09:00
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Post: 11901235
Originally Posted by Greenlights
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 ,?
The answer is: it depends. Modern aircraft and the performance software used to generate thrust settings and v-speeds have a complex interplay between regulatory requirements, engine wear, runway length, obstacles, Company policy, etc. Without knowing the entirety of what the calculations were based on it would be hard to say for sure. Also, remember the performance is predicated on losing half the thrust at V1 and continuing the takeoff: if you have had both engines running for a while after that and you retract the flaps early, you are already well above the net single-engined minima, both in terms of speed and altitude, so some fat in the system. Also, if the V2 has been increased artificially, you may have adequate manoeuvre margin after retraction and be far enough along the drag curve for it not to be too problematic. All that said, it is definitely a bad idea to do this off-schedule!

Subjects: Flaps (All)  Flaps vs Gear  V1  V2

FullWings
2025-06-14T16:33:00
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Post: 11901629
Originally Posted by Four Turbo
Has the rest of the fleet been grounded? If not they must have a fair idea of what caused this. And it is not something that is about to happen elsewhere.
AFAIK no groundings yet but we do not know for sure that there has been a successful readout of the DFDR. If it sustained damage or the interface electronics are non-functional, it\x92s not unusual for them to be taken to a secure lab at a *AIB where experts can attempt recovery using whatever advanced methods they have available. This may take time as they don\x92t want to lose data in rushing to extract it.

Subjects: DFDR

FullWings
2025-06-14T21:17:00
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Post: 11901843
Originally Posted by LTC8K6
IIRC, you would get a warning if you try to retract the flaps too early in the 787.

The gear and flap controls are not easily confused in the 787. They look nothing alike and are not near each other.
Agreed. Also, given an almost 100% likelihood that the RAT deployed pretty early on and the ramifications of this, flaps and gear have almost lost relevance as they wouldn\x92t be able to be moved much after that point during the brief airborne period, even if commanded?

Subjects: RAT (All)  RAT (Deployment)

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FullWings
2025-06-14T22:21:00
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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
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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?

Subjects: DFDR  RAT (All)

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FullWings
2025-06-16T09:47:00
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Post: 11903332
Originally Posted by Icarus2001
My information differs to yours, We do know the EAFR was recovered on Saturday. Are you suggesting that it sat in a room for three days?
As mentioned several times in this thread:

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

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FullWings
2025-06-18T08:46:00
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Post: 11905031
Originally Posted by brokenenglish
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.
I think the minimum autopilot engagement height is a FCOM limitation but not necessarily a limitation of the system, i.e. you can engage the AP lower than that but it hasn\x92t been technically qualified to work in all circumstances, although it might actually do that. Much like autolands on the B777 which specify F20 or F30 - it works fine with F25 in the field but it\x92s not certified. I know from personal experience that the AP on the 777 will engage below 200\x92 as I did it myself when the cockpit started filling with acrid smoke during rotation and needed to get the mask on ASAP. You used to be able to engage it on the ground (there was an RTO some while back due to \x93stuck controls\x94) but that might be inhibited now.

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)

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FullWings
2025-06-18T09:22:00
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Post: 11905053
Originally Posted by Roo
No it is actually a system limitation on the 787. A/P won't engage after TO below 200' rad alt. There is some form of interconnect/lockout in place. If you try engage at 195' you just get the AP disconnect tone.
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
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Post: 11905114
Originally Posted by Roo
Yep numerous times in the sim over the years. Typically when overly exuberantly trying to get AP in after a V1 cut. RA is right in your face on the HUD & if you don't wait til 200' RA, AP will not not engage.
That is even more interesting. On the triple, quite a bit is referenced to the altitude at the start of the takeoff run and uses barometric (which is effectively QFE), such as AA, Thrust reduction and EO. If the runway sloped down and/or the ground fell away at the end of the runway, as it does at many airports, you could engage the AP well below 200AAL on the 787?

Subjects: V1

FullWings
2025-06-18T13:12:00
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Post: 11905236
Originally Posted by The Brigadier
As I said in a previous post, every day that passes without a EAD suggest the cause was was specific to that aircraft (fuel contamination, maintenance failure, crew error - pick you own theory)
Yes and no. As the investigating teams are not issuing running updates (and neither should they) we don\x92t know what stage of the process they have got to - the DFDRs might still be in a lab somewhere with a team of experts working out how to get the data out without compromising it. Or they could have the data but be none the wiser as to the cause(s) of the accident - Jeju comes to mind.

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
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Post: 11905837
Originally Posted by StudentInDebt
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.
100%. As pointed out many times, this accident just doesn\x92t fit with either performance errors, flap/gear mis-selection or inappropriate AP/AT modes. The flightpath was as expected until shortly after liftoff, then we see/hear RAT deployment and an unpowered descent into the ground. There are still plenty of possible reasons as to why this occurred but to date we can\x92t really narrow it down any more.

Subjects: RAT (All)  RAT (Deployment)

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FullWings
2025-06-20T09:43:00
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Post: 11906781
Originally Posted by lederhosen
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?
Under most circumstances you would apply the benefit of the doubt but as the RAT deployed (something there is a lot of evidence for) it strongly suggests this. Yes, the RAT can deploy for other reasons but that would imply an even greater level of coincidence than two engines failing in a short period (3 hydraulic systems, 4 generators, etc.). The distance they went until ground contact also ties in with a loss of pretty much all thrust, as does the audio recording of idling/windmilling engines. There is also the fact, which may turn out to be an assumption, that any failure of other aircraft systems should not affect engine operation as a) the engines are effectively self-powered in flight and b) the engine controls on the flight deck are part of an isolated system powered by the FADECs.

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
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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.
It\x92s a possibility (as is virtually anything that doesn\x92t break the laws of physics) but all the training, practicing and checking would have been to emphasise SOPs, which are to leave all the engine controls where they are until you have done a proper interactive diagnosis at a safe height with the flightpath assured.

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
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Post: 11908793
Originally Posted by TURIN
How can that bug affect two independently controlled and powered engines, at almost exactly the same time?
That\x92s the nature of a common mode bug. If the software was vulnerable to Mars being in the house of Uranus, the scent of lilacs and the DOW being less than 42,000 then you\x92d expect the failure to occur everywhere when these conjoined. Same when an aeroplane\x92s systems and/or the environment present data that triggers an unplanned/unforeseen response in something like an EEC/FADEC. The experts still appear to think that this is unlikely but we have been presented with an unlikely occurrence...

Subjects: None

5 users liked this post.

FullWings
2025-07-01T06:45:00
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Post: 11914044
Originally Posted by 13 others
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.
Quite. If all we had to go on was the position of the crash site it might have made sense but we have video and audio of pretty much the whole thing, plus a bit of ADSB. You could almost say that we now know how far a 787 will go when it loses all useful thrust just after rotation.

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