Posts about: "RAT (All)" [Posts: 683 Pages: 35]

One has to assume that, given the seeming lack of lateral deviation from the flight path, and with no obvious yawing or rudder input visible on the videos, there's only two realistic conclusions here? Simultaneous dual engine failure of unknown cause if the RAT was indeed deployed; or flaps reduced too early leading to a stall if the RAT wasn't deployed.

Evidence in this thread would lean me toward the RAT deployed and therefore dual engine out scenario. As for the cause of that, well, only a couple of likely scenarios exist that could cause simultaneous shutdown of both engines, including mistaken or intentional use of the fuel cutoff levers.

So what is known at the moment?

- The flight crew consisted of an experienced Captain and a First Officer with a little more than 1000 hours. Whether or not this flight was a training event appears not yet determined.

- The aircraft departed from Ahmedabad, using full length of the runway, lifting off at an appropriate distance from the departure end and reaching an altitude of less than 1000ft before descending again to an impact. It therefore got out of ground effect. Also, the power selected for takeoff was sufficient to get the aircraft airborne within the constraints of the field.

- The landing gear was left down much longer than usual and remained so for the whole duration of the flight.

- Flaps appear to have been extended normally to a setting not triggering any pre-takeoff configuration warning. On the 787, extended TE flaps are not as obviously visible as on other types, especially with low quality pictures, but a gap between the flaps and the wing proper was visible, showing a glimpse of the engine nacelle through it.

- Whether or not the RAT was out appears not entirely clear, although there are strong indicators of it being deployed. If this is confirmed, this seems to point to a major engine or electric issue.

- Engine noise is surprisingly low on the available videos, either drowned out by environnmental noise (the 787 is not a noisy bird) or due to lack of power produced.

- Descent was at a very high AOA and appears not intentional. The crew did not decide to push the nose down.

- The aircraft appears to have been structurally intact with nothing issuing from it. No debris, smoke, fumes or liquids were in trail, no parts were observed to have been lost or dropped.

- There seems to have been a mayday call from the aircraft, possibly indicating power issues.


The crew seems to have found no reason to abort the takeoff before V1. Whatever befell them must have struck past that speed and given them cause not to retract the landing gear. Whether the lever was not moved or the systems did not react to it is not determined yet.

The aircraft had enough energy to climb to about 600, in any case less than 1000ft altitude. Ahmedabad seems not to call for a specific NADP, but whether it was NADP1, 2, A or B that was flown, it is fairly safe to assume that its normal regime would have been takeoff power and takeoff flap settings at that time.

Multiple other aircraft departed from or arrived at Ahmedabad before the accident, of which at least one must in all probability have taken onboard the fuel from the local bowsers in substantial amounts and used it without troubles, or else there would have been other flights in trouble due to this.

I am awaiting the preliminary report from the authorities and the readout of the data recorders with much interest.

I\x92d like to ask a legitimate question here regarding the runway footage.
there seems to be little to no change in aircraft attitude from point of lift off until just before impact.
I have no experience on commercial jets, so I am waiting to be corrected, but first thing in engine failure after take off is lower the nose? If RAT deployed they should have at least been able to do so?
The fact the attitude remains unchanged, would this not suggest they at least thought they had a chance of flying their way out of this situation?



im sure 787 is not prone to pitot/static blockage?

time will tell, until then we can only speculate I guess.

Every 757/767 built has a RAT. When you did your walk arounds it was the large rectangular panel near the right aft wing root. Normally it was outlined in red and we were advised not to walk under it. If for some reason it extended the extension was somewhat violent and you would not want to be under it. Where were your ground schools?

SLF ... does this not seem pertinent, given the discussion about RAT deployment?

We haven't thought about it because it didn't happen. We have a video of the plane with no engine sound and the RAT clearly audible. The RAT is also visible in the video. The pilot sent a mayday mentioning loss of power. The only survivor says the cabin went dark and lights were flickering. It's pretty compelling no?

Why are people still talking about flaps and incorrect takeoff data settings?

Well of course they didn't understand what's going on. Something happened to them that has happened to a handful of people in history and is supposed to be essentially impossible. They didn't have the 'luxury' Sully had of a few thousand feet safety of altitude margin to think about it either.

Of course the didn't know why they'd lost power, they just knew they'd lost it. Yeh they would have felt pretty helpless 200 feet above the ground surrounded by tall buildings. My heart goes out to them being by that point no more than passengers to their own death. At least the actual passengers didn't have to watch the building coming at them knowing there was no escape. It's unthinkable.

So I don't know how on earth you think this suggests the flap theory. You're reading an awful lot into the words of a man who was likely processing the fact he's about to die in a horrific way.

Can we just forget about flaps? We have pictures of the wing at the crash site with flaps extended. The plane is on video with no engine noise and the RAT audible and visible. The pilot sent a mayday saying they'd lost thrust. The only survivor says the lights were flickering and the cabin went dark. Why are some people so desperate to pin this on a pilot mistake there is zero evidence for?

The visual evidence of the RAT being deployed (or not) is a bit dubious, but the audio evidence is pretty solid. It's also corroborated by the best eye witnesses we have, the pilots, explaining that they had lost power in their mayday call. And corroborated again by the second best eye witness we have, the passenger who survived, commenting on the 'green flickering lights' of the emergency exit signs indicating power loss. And corroborated again by the (now confirmed) posts on social media from the previous set of passengers complaining that aircon, entertainment, lights etc on the plain weren't working.

The idea that the flaps weren't set for take off also seems incredibly dubious given that in several frames of the original footage you can see the engines through the wings, on both sides, something not explainable by grainy footage or compression artifacts, and only possible if the flaps are down.

Edit to add: the reports on social media from the previous passengers complaining about non-functional electronics have been confirmed

One thing which could cause simultaneous unexpected idle power is the autothrottle. I'm thinking about this, leading to a crew too startled to retract the gear and too distracted to push the thrust levers forward, as a possible cause. As others have said, the RAT could have been manually deployed - an action which would make sense to pilot convinced that he was about to lose both engine driven generators.

I would rule out bird strike for lack of audio visual signatures of such an event and fuel contamination due to symmetry of events. Due to my trust in the profession and my distrust in modern engineering practices, my money is on Seattle.

Especially when the video is clearly taken on the ground, when you could easily expect source switching due to shutting down an engine for single-engine taxi, then switch to APU, then ground power.

IIRC the CVR battery (in this case EAFR battery) is required to power at least the cockpit area microphone, if not the pilots' mics.

Once the RAT deployed at least some data should have come back.

This has been discussed upthread and has happened before (on a 777 IIRC) but did not result in a crash.

It does not explain the RAT and generally you would expect crews to shove the thrust levers fully forward.

If the fuel was cut off, how long would it take until the engines spooled down? How long would it take, given wind-milling etc, for that to result in a loss of power? I'd love to see a timeline of the flight with the fuel being cut off that is remotely compatible with the events we saw, because I don't think it's possible.

I had wondered about TCMA being involved. Software is extremely complex and there have
been examples in the past where it does something it wasn't supposed to do, causing an incident.

Edit: How do we know it happened at 100ft?

I'm trying to explain the appearance of the RAT and the onboard green/white flashing lights. The alternatives right now are dual engine failure with no birds around.

There would be way much going on for anyone to even think about deploying the RAT. They've literally just left the ground and find themselves in a state where the plane is not climbing for a currently unkown reason. If you haven't thought to advance the thrust levers fully you definitely won't be looking up to the overhead panel to press deploy the ram air turbine during a critical phase of flight.

What? No, no, and no. Just no. On many levels. Stick to reading

I said below 100 feet, it didn't get higher than that. Are there any memory items, or indeed emergency checklists, to complete between V1 and 400 feet?

It looks like you recall correctly. This skybrary PDF document "Fade Free Memory" describes the EAFR

https://skybrary.aero/sites/default/...shelf/2955.pdf

I quote from it:
That seems to indicate that as long as the forward EAFR is powered, the datastream from the cockpit area microphone will be available to both EAFRs (assuming the network to the aft EAFR is available and working).

The whole document is worth reading to glean more details.

Sigh. That about wraps it up for CRM then?

JG1 In the many hours it's taken me to read every post, there seems to be a few major areas of confusion that just keep running, repeatedly, in parallel.

The You Tube captain in his red and white box seems to be logical, but not much is gained. However, he does state quite categorically that the cloud of white dust is showing the aircraft to be unsticking very near the end of the paved surface. I think it's vital that this thread gets some very basic issues agreed on or a universal agreement that we don't know.

What echoes clearly in my mind is Mike Lithgow's crash footprint. The BAC 1-11's shape was clearly recognisable after the deep stall.

The bang mentioned by the survivor. If the RAT becomes a disc before being fully out, it would snap sharply into its locked position. I can well imagine this being audible. However, the timing of this leaves my mind open for another reason for the noise. I don't think the RAT would be out that soon, but I don't know.

Having time and again run the video from left rear, where it goes behind the little wooden structure, I'm convinced it was powered one moment, and totally un-powered, the next. Yes, it leaves one with some very uncomfortable scenarios as possibilities. But that's all they are. Pulling into a deeper stall in the last moments is just being human.

Related question: I asked earlier at what speed the 787's RAT becomes effective in providing hydraulic power. Is it possible that by the time the RAT deployed, the aircraft had lost airspeed to the point that it would have struggled to produce an adequate amount of pressure? Taking the Gimli Glider incident as an example, my understanding (could be wrong, this was from a magazine article) is that as they bled off speed to land, they ended up short enough of hydraulic power that they started to experience control difficulties, with the plane responding fairly sluggishly. If that's the case and this poor crew was going through something similar, it might explain why they seem to do very little about their situation.