Originally Posted by Machinbird
Bearfoil's concept is a wild hare and should be disregarded.
Many odd concepts are strangely resurfacing and some progress are unduely discarded while, at the same time, we are closer from knowing the truth from the inquiry. Hence, I'm a bit cynical and sceptical of the reaction if it won't fit those "deep stall from FL350" theories.
Originally Posted by Machinbird
We do have actual wreckage this time and it is located very close to LKP pretty much down track, and indicating a descent to the water that almost guarantees it was in a deep stall.
Maybe, maybe not, and I believe more the later.
But then, my point is that if she was in a "deep stall" situation, she certainly has not departed at once from cruise level (or even higher) at 0210 (or even earlier). A four minutes and half ride of "deep stalling" would have to start above 80,000 feet in order to fit with a crash time post 0214:26. Then how the hell would she have reached such a level flight?
At best, a single unrecoverable upset would have started 90 or 120 seconds later than 0210. But now, the distance finally covered would be puzzling (but who knows which exact track she has actually followed down to the sea!).
But those 90 to 120 seconds would have been all in ALT2 Law. Here, it is not so hard to understand that an aircraft deprived of most of its protections against "abnormal attitudes" might more likely "upset" in certain conditions than when it was flying in "fully protected mode" (before 0210).
Originally Posted by Machinbird
The aircraft is not supposed to fall out of the sky while in full cruise, and the flight control system is designed to guard against departures from controlled flight, so something undeniably happened that the flight control design folks did not forsee.
This "something not foreseen" is very likely the consequence of more than one event, a chain of events, rather than this simple "computer glitch" explanation which looks much more like a greviance against all those computerized automatisms, by principle, rather than a fully reasonned analysis. Hence, me being cynical/critical about this stance.
Originally Posted by Machinbird
Tubby's concept may be slightly over-elaborated but has significant potential to explain what happened. Your expectations of engine stall at high AOA may be unreasonable.
Tubby's concept is not only slightly over-elaborated, it just doesn't fit with many facts. My point about the possibility that engines would have experienced some notable troubles during such "4.5 minutes deep stall" is only one amongst many others in opposition to such conclusion.
The process of the pitots icing at cruise level is now well documented for the A330 family: no event ever caused an excess airspeed reading. In fact, the contrary: a drop of airspeed (down to 60 kts) followed by a possible (and false) low speed "stall" alarm. Hence, if a rogue C-3PO would become confused, it would trigger a nose down order instead of a zoom climb!
Anyway, he could only be confused by a very slow build up of ice, then he would never recognize the truth, then, never trigger an UNRELIABLE A/S at all.
Nonetheless, you would have the risk of a very different "upset" in perspective (an high speed stall) and not a "deep stall".
The recovered RTLU (Rudder Travel Limiter) settings are showing Mach 0.82 at 0210 (when it faulted due to this unreliable airspeed). It is neither Mach 1 nor 60 knots, but the current cruise speed planned at FL350. Consequently, we may be 99.9% sure that those faulty airspeed imputs were correctly detected by the system when the aircraft was not stalled in either way, being still at cruise level and not in an abnormal attitude up to this point. The following system action was then, as per design, to revert to ALT2 Law by turning off all those affected protections, Hence, avoiding to trigger a false "protection" due to those unreliable airspeed data.
Originally Posted by Machinbird
About the best we can do with the data we have is try to match endpoints and any event data that ACARS provided until we see actual aircraft data.
It all fits in a context. AF447 did not do the impossible. We just have to be clever enough to figure out how it did what it did.
Correct. Let's try it then.
S~
Olivier