Originally Posted by
HazelNuts39
One way to stall an airplane is to gradually reduce airspeed at approximately 1g. The speed at which the airplane then stalls is called the 1g-stall speed, or Vs1g. In the conditions of AF447, such deceleration would take of the order of 1.5 - 2 minutes.
During which time the Aircraft would travel a distance of roughly 10 - 15nm i.e. way beyond where it is supposed to have been found now.
On the other hand this would leave roughly 2,5 - 3 minutes for the descent to the sea which sounds quite plausible for a fully stalled A330 at cruise weight.
Finally, it should be said that a stall is a temporarily uncontrolled, but usually recoverable condition, provided the pilot recognizes it and takes the right actions. The stall is identified by buffet of increasing intensity, usually becoming so intense that, in regulatory language, it is an effective deterrent to further reduction of speed or increase of load factor. To 'unstall' the airplane, the AoA must be reduced below that at which it stalls.
That is the mysterious part about it: why would they let it get into a fully developped stall. In an Aircraft of the momentum and mass of the A330 going from normal flight via incipeint stall to fully developped stall is unlikely to happen in a fracture of a second.
At least in straight and level flight this process takes time.
And leaves time to react.
(we are not talking about a Cessna here)
All things combined, the conclusion could be that it is not likely that the airplane stalled at 2:10, and remained stalled all the way down to the surface.
I strongly tend to agree.
Given the fact that it took overall 5 minutes and brought the plane effectively ~6nm down and ~5nm forward from LKP, I strongly tend to agree.
In a straight line this amounts to ~8nm in 5 mins which equates to net ~100kts if it were to go down in a straight line starting at 2:10 at LKP.
Impossible in an airliner where both min horizontal (~350kts at 35k going down to ~200kts at S/L) and min vertical speed (~200kts at 35k going down to ~140kts at S/L) alone are much higher. This simplification even ignores the fact that it started probably at ~450kts at LKP, so the net average speed towards the end would have to be even lower.
My conclusion: The way down must have been significantly more complex.
A multi stall scenario seems more likely.
I still see the possibility of certain decelleration following the loss of Airspeed Information followed by an accelerated stall e.g. due to vertical gusts leading to a massive wing drop as a potential entry scenario into the disaster.