The direct cause of 447's crash will not be "direct". To get to a single vector is impossible.
A starting point would be the untoward (and shamefully anticipated) dump of the a/c control into the hands of the PF. It had happened, though likely not ever in such piss poor conditions. This makes the foot dragging inexcusable.
There are no explanations, only excuses. Because all the precautions, all the preventions, were inadequate. How about that, then? One cannot focus on a single iteration; they were without exception, re-iterative.
In a perfect World? OK. PARK IT. FIX IT. Won't happen. I cannot say it cannot, but it won't.
That is why TRAINING is such a whine. And since it is a whine, it is dishonest, and arguably criminal. It is also self incriminating, the Pilot group does not self train.
Airframe?
The two or three glaring problems won't be fixed, too expensive.
What was known, and when did it become so? Ask that question of Socrates, or some modern day Solomon. It will be ignored.
PITOT. STALLWARN. THS. UAS Procedure. (This last, alone, food for an action at LAW that would cripple the players, and indict the Authority.)
When "corrections" can be applied before the engines have cooled, does one not think that the problem was a priori?