Originally Posted by Machinbird
Originally Posted by Takata
No-one can so far explain why switching at 0210 to ALT2, due to unreliable airspeed, would cause an immediate upset as none of the similar events ever caused one! After being switched to manual control, any manual imput could cause one in relation with other unknown factors (workload, weather, technical, etc.)
Perhaps this is stated backwards.
"Why would an upset cause unreliable airspeed indications??", might be a better question.
The answer is in the link below and subsequent discussion.
AF 447 Search to resume
Note: With the discovery of the wreckage virtually under its 2010 position, the case for an immediate loss of control becomes stronger. The key question becomes how can it happen?
Well, sure, this question maybe stated backwards as, in my opinion, it can't be totaly ruled-out so far. Nonetheless, the A330 operational records should speak by itself as the probability for an "upset" happening some time before 0210, while flying in automatic (protected) mode at cruise level (A/P and A/THR ON) is clearly very very close to zero if related to her systems behavior.
One should remember that the only "system glitch" recorded after more than 15 years of operational duty accross a fleet of several hundred long haul aircraft was QF72. One will also note that this aircraft used a different (faulty?) hardware and would remember that this issue was not an "upset" properly: in fact, even if this situation could have caused some serious harm to the passengers, it did not cause an "upset" as the aircraft did not departed from its safe flight envelope (which doesn't mean that this problem was not dangerous for the aircraft safety).
Now, that the weather alone would put suddendly this aircraft close to an "upset" attitude, while flying in automatic mode at Mach 0.82, would certainly disconnect everything the same way. Then, if this was followed immediately by the freezing of all the probes, this would be quite a serious situation for the crew to manage. In this case, this would mean that they were not aware of the weather situation as they were not flying in "turbulence penetration mode", having their A/THR still ON up to this point. This would also be contrary to the right AF procedure and any cautious weather management at this dangerous spot.
Tim Vasquez' weather analysis was good but it pictured an aircraft position which was wrong as he took the projected "0215" position as reference alongside a wrong 0210 position.
concerning the wreckage position, I still doubt the 5 minutes "flat spin theory" direct from FL350 at a rate of 7,000 ft/mn while she was still powered all along her "free fall" (as no dual flameout occured). But who Knows?
The "deep stall theory", from the same level, will certainly imply a quite different aiframe (with T tail) and much more distance covered from LKP. The crash time (based on ACARS sendings) was estimated by the BEA between 0214:26 and 0215:14.
But, of course, it may have happened later in time, if she was not powered anymore after this point, as nothing, so far, can rule-out also this possibility.
We'll see what is found in the deep sea.