OVERTALK,
Why the TCAS? It needs the static pressure to be in agreement (and good) for a highly accurate RVSM flight level maintenance.
Why was the ACARS TCAS FLT msg not explained by the BEA? Your logic is not in question, and the scenario you have promoted fits well with the assumed outcome.
mm43
TCAS derives its altitude information from the aircraft altimeter (i.e. its mode Charlie squawk that's continually being punched out in response to ATC and TCAS interrogation via the transponder). If the ADIRS is suddenly in WTF? rejection mode for increasingly divergent derived static pressures (due to the pitot blockage rate increasing), then two things must happen:
a. Autopilot baro hold will be corrupted and so the autopilot will kick out and....
b. TCAS will throw in the towel (and ACARS will be stimulated to tattle-tale that info also)
Same thing (essentially) happened when the BIZJet copilot placed the laptop on the center console over the Amazon jungle and its lid cancelled their transponder - effectively crippling their TCAS (which then showed a non-flashing and bland TCAS message on-screen)- for quite a while before their connecting with the GOL 737....
But then again, ACARS wasn't part of their bizjet repertoire. In their case their baro hold was good, but it was still the TCAS that had been fatally disabled. In Af447's case their TCAS merely lost that valid mode C input. ...and quit.
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and then Machinbird said:
The fact that AF447 arrived at the surface apparently essentially intact and apparently at low speed, high angle of attack, high sink rate and perhaps in as little as 5 minutes requires an involved process if one assumes an initial overspeed departure from controlled flight.
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Hmmm
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For a non T-tail, a sustained deep stall is not really on the cards. A flat spin maybe? Not really. The A330 aerodynamics don't support either proposition. A double flame-out due to a nose-high departure and auto-rotation following a Mach Crit encounter and loss of control? YES, most affirmatively. WHY?
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Well Airbus test-pilots don't test for any flame-out proclivities during stall or coffin corner auto-rotation, however the A330's engines would be quite vulnerable to that at cruise height (see recent Pinnacle Airline's example). My guess is that the AF447 crew were burning off height at a great rate attempting relights all the way down and then, logically, were eventually forced to give up on the relight attempts for an engine-off, best configured/best attitude/best speed arrival at ditching station "terra oceana". That's what could have happened to Air Transat's A330 - if the Azores hadn't been in their sights all the way down.
That explains it all via Occam's Razor first principles - as modified by arody logic (IMHO).
The links at:
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Part ONE:
Air France Flt 447
Part TWO:
The AF447, QF72 and 9M-MRG comparison
contain a quite convincing version of the likely AF447 event.
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