Pages 222/223 and 224 are probably the most important of this thread (for indisputable bottom lines):
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However we are getting this "illogical non-sequitur" rejoinder from a number of posters. i.e. Why would a high-speed autopilot disconnect and possible Mach Crit encounter terminate in a high descent rate, nose-up, wings-level, slow-speed arrival at the impact point? Perhaps some extracts from prior posts can clarify "how":
The Conundrum
#4433
....however I am having great difficulty in understanding how an overspeed induced departure will lead to other than a sky full of confetti.or a high speed impact with the water. The fact that AF447 arrived at the surface apparently essentially intact and apparently at low speed and 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.
and
#4461
The High-Speed-Event does IMHO not fit to the final touchdown in the ocean (Time, location, attitude, speed, sinkrate, found evidence), there must be something else.
==> the responses
#4428
Disorientation after a Mach Crit/Mach Tuck encounter inducing a loss-of-control could easily later lead to a nose high/stall entry type ituation. Why? See later (see #4430 et seq - below).
Personally not sure about the plausibility of a double flame-out (from a post-disorientation stall/spin scenario) and failure to relight - culminating in an attempted engines-off ditching (as an explanation for
the assumed wings level water-entry attitude, high RoD and low speed).
The 4 minutes (only) from height could be explained away by the high speed/high RoD required for relight attempts OR that those 4 minutes just represented the time from height to losing all useful electrics (to the ACARS) due to a LOC induced double flame-out.
#4430
Note 1: "Ok, lets follow that line of thought a bit further. The nose starts to tuck (i.e. drop) as trim limits are reached (because of the shifting center of pressure on the wing as you go transonic) and the nose starts to fall, altitude starts to unwind quickly and the crew reacts by reducing power and deploying speed brakes. Assuming they are successful in arresting the plunge, what is the next thing they would encounter? It would be a transonic pitch-up as they decelerate (caused by the center of pressure moving back to its normal subsonic position) as all the nose up trim makes itself felt. Say the aircraft bottomed out at FL 250 while pulling maximum permitted g, and just below M Crit. In an F-4 for example, this type of transition to subsonic could cause a 50% 'g' overshoot because it happens very quickly. Can the Airbus G protection mitigate this 'g' spike quickly enough to keep the wings from breaking (while in alternate law and with an aft cg)?
Would the wings stay on? I don't know since I don't have enough aircraft data, but if the wings did stay on, then you would probably soon find the nose pretty high in the air since the crew would be unlikely to have the presence of mind to drop a wing. Then you could get into a deep stall very quickly. But, can the critical Mach recovery even be made in Alternate Law?
#4434
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?
.
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 CRJ 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.
Conclusion: Yes Virginia, a loss of control, stall/incipient autorotation/spin could cause a double flame-out due to intake blanking. The ensuing high-rate/high-speed descent would quickly dump altitude (relights are notoriously unsuccessful at higher altitudes anyway). Eventually the crew would have to give up relight attempts for a controlled engine off arrival at sea-level.
There's a good chance that this would explain the condition of the recovered debris and bodies. Degraded flight controls, nil flap, nil L.E. devices and sea-state would have made any such attempted ditching valiant - but doomed to failure.