Posts by user "DaveReidUK" [Posts: 55 Total up-votes: 202 Pages: 3]

Originally Posted by ATC Watcher

from the EASA statement yesterday :

No mention of UK

Originally Posted by dbenj

I agree. It is intriguing that we have none of the radio communication released.

Originally Posted by QDM360

People really need to stop using FR24 data if they don't understand it.
This FR24 recording of AI171
https://www.flightradar24.com/data/f.../ai171#3ac3097
only consists of 4 unique ADS-B data messages. The first two were on the apron/taxiway. Then one at the runway intersection. And the fourth and last one just after the aircraft became airborne. That's all.

The two last ADS-B data messages are more than 4 minutes apart. It was 8:04 UTC when they entered the runway at the intersection. The next and last data point was received at 8:08 UTC.

The map view connects these dots, so it looks like a proper track. But in reality the ADS-B receiver barely received anything. It's therefore silly to argue the aircraft stopped transmitting ADS-B data based on this poor recording. The only thing you can say with certainty is that FR24's ADS-B receiver at Ahmedabad has really, really poor coverage...

Originally Posted by AirScotia

I've been 'watching' flights take off from Ahmedabad on FR24. Assuming that the bold dots on the track are where FR24 gets some real transponder data, it looks as if flights become visible at take-off, then FR24 interpolates the track until roughly 800m/1km from the end of the runway when it gets the next 'real' data block. So all we can conclude is that the transponder stopped transmitting somewhere in the 8 - 10 seconds between take-off and 1km.

Originally Posted by SQUAWKIDENT

Please stop posting information from this commercial aircraft spotter site. It is frequently inaccurate. ADS-B site free to use and more accurate IMHO.

Originally Posted by tdracer

Another hour spent sifting through the stuff since last night (my sympathies to the mods ). A few more comments:

"Real time engine monitoring" is typically not 'real time' - it's recorded and sent in periodic bursts. Very unlikely anything was sent from the event aircraft on this flight.

Commanded engine cutoff - the aisle stand fuel switch sends electrical signals to the spar valve and the "High Pressure Shutoff Valve" (HPSOV) in the Fuel Metering Unit, commanding them to open/close using aircraft power. The HPSOV is solenoid controlled, and near instantaneous. The solenoid is of a 'locking' type that needs to be powered both ways (for obvious reasons, you wouldn't want a loss of electrical power to shut down the engine). The fire handle does the same thing, via different electrical paths (i.e. separate wiring).

As I've noted previously, a complete loss of aircraft electrical power would not cause the engines to flameout (or even lose meaningful thrust) during takeoff. In the takeoff altitude envelope, 'suction feed' (I think Airbus calls it 'gravity feed') is more than sufficient to supply the engine driven fuel pumps. It's only when you get up to ~20k ft. that suction feed can become an issue - and this event happened near sea level.

Not matter what's happening on the aircraft side - pushing the thrust levers to the forward stop will give you (at least) rated takeoff power since the only thing required from the aircraft is fuel and thrust lever position (and the thrust lever position resolver is powered by the FADEC).

The TCMA logic is designed and scrubbed so as to be quite robust - flight test data of the engine response to throttle slams is reviewed to insure there is adequate margin between the TCMA limits and the actual engine responses to prevent improper TCMA activation. Again, never say never, but a whole lot would have had to go wrong in the TCMA logic for it to have activated on this flight.

Now, if I assume the speculation that the RAT deployed is correct, I keep coming up with two potential scenarios that could explain what's known regarding this accident:
1) TCMA activation shutdown the engines
or
2) The fuel cutoff switches were activated.
I literally can come up with no other plausible scenarios.

In all due respect to all the pilots on this forum, I really hope it wasn't TCMA. It wouldn't be the first time a mandated 'safety system' has caused an accident (it wouldn't just be Boeing and GE - TCMA was forced by the FAA and EASA to prevent a scenario that had never caused a fatal accident) - and there would be a lot embarrassing questions for all involved. But I personally know many of the people who created, validated, and certified the GEnx-1B TCMA logic - and can't imagine what they would be going through if they missed something (coincidentally, one of them was at my birthday party last weekend and inevitably we ended up talking about what we used to do at Boeing (he's also retired)). Worse, similar TCMA logic is on the GEnx-2B (747-8) - which I was personally responsible for certifying - as well as the GE90-115B and the 737 MAX Leap engine - the consequences of that logic causing this accident would be massive.

Originally Posted by FullWings

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

Originally Posted by VR-HFX

Yes indeed. I strongly leant toward the incorrectly set AAI and VNAV capture and level off as the a/c reportedly reached max alt of 625ft or about 450ft AGL.

Originally Posted by CurlyB

The long runway roll in the tagline has not been proven, as seen many times in this thread

Originally Posted by Aerospace101

This is an important distinction because the Center hydraulics which is solely electrically pump driven (not engine) only had enough power to tilt the bogey, not open the doors.

Originally Posted by fox niner

Then the gear.
When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again.

Originally Posted by MaxRange120

https://www.gov.uk/government/news/a...a-flight-ai171

UK AAIB Link here for updates

Originally Posted by Gupeg

Looking at the raw data in your post, and given the speeds are likely IAS based i.e. can be affected by wind

Originally Posted by modcat

Heard about CM1 seat runaway and thr levers moved back?

Originally Posted by EXDAC

But as previously posted a recorder is only as good as the systems that provide the data to it. If those systems, or some of those systems, are not powered the data is simply not available to be recorded. You need the DFDAU (or equivalent) to be powered and you need the systems that feed data to the DFDAU (or equivalent) to be powered and operational.

Edit to add - RIPS will likely maintain CVR function.

Originally Posted by Barney Rock

Me thinks one cannot depend on ADS-B da6a at such low altitude. Lots of errors.

Originally Posted by OldnGrounded

Thanks for the heads up. The story also says, "No cause has yet been identified for what would be an extremely rare power loss from both engines, but on Sunday the Indian civil air authority (DGCA) began urgent pre-flight inspections of fuel systems, electronic engine controls and other systems on Indian Boeing 787s."

And it quotes Juan Browne (Blancolirio): \x93There was something terribly wrong with this 787 jet and we need to find out really quickly what went wrong because we\x92ve got a thousand of these operating today and operators need to find out what happened.\x94

Originally Posted by dragon6172

One comment here, and maybe I am mis-understanding your comment, but the landing gear only operates via the center hydraulics. It does not matter whether the Left/Right engine driven hydraulic systems are operative or not. The RAT will only pressurize the primary flight control portion of the center hydraulics.

Originally Posted by Icarus2001

Should we talk about the RAT being an electrical generator? No? Okay then, carry on.

Originally Posted by Lord Bracken

Absolutely. This confidence that the EAFR has already been read is misplaced. It’s a specialist piece of equipment and probably can’t even be downloaded in India. It’s most likely on its way to the NTSB, the BEA or the AAIB (UK) for analysis which will be done under strict conditions (for obvious reasons).