Engine-eer said: "When the system is in alternate law the auto-trim function is disabled. Pushing the stick forward only results in limited elevator motion. Trim must be addressed by the pilot in this mode, so simply pushing the nose down isn’t going to retrim, the pilot has to do it manually.
This still doesn’t address why the trim was moved to the 13 degree nose up position."
I'm a little uncertain about this horizontal stabilizer position of 13 degs nose-up (from an initial 3 degrees prior to A/P and A/T disconnect). Is it a trim-wheel setting or does it refer to the horizontal stabilizer being 13 degrees up at the leading edge (i.e. a nose-down couple setting). If it's the latter then perhaps the pilot was fighting the post A/P disconnect out-of-trim involuntary pitch-up by manually winding in some nose-down trim..... as he sought to oppose that pitch-up.
However if the Shadow's version of events leading to the zoom climb are correct, when the aircraft topped out circa FL380, it was sporting high power and entered its stall quite ballistically, whilst out of trim. I've a hunch that a stall entered thusly at a very high altitude is itself a very different kettle of fish ...... to the common garden variety level flight approach to a stall (the classic 1kt/sec deceleration). Try throwing (i.e. propelling) a paper airplane off a cliff and then compare its trajectory with one dropped in a level flight attitude. I know that propulsion isn't in that equation but you get the idea, right? What I'm leading up to is that it's not a flight-tested regime for airliners and it may well be embedded and unrecoverable at 40 degs AoA. You might have to try configuration changes or engine asymmetry to become aerodynamic again.
I could liken it to a fall into an inverted attitude from a hammerhead tail-slide stall with fwd stick (one of my favourite low-level aero routines). You needed to throw out the ventral airbrake to get a good rate of re-pitch to the downward vertical for recovery (looks very different with/without that airbrake inject - you can tell from the smoke). Without the airbrake, on a video you can see that invtd stall attitude remaining constant for the descent. That was a theory behind Skippy O'Dwyer's death whilst doing that same stunt.
Some dynamic and ballistic entries to stalls/spins can have surprising results. Anybody who's flown inspin aileron on a JP-5A spin entry will know to what I refer.
The BEA's contribution on 27 May was just a data-dump. It's too early to conclude anything about how those AF447 pilots coped with that sudden pitot-initiated maelstrom. But it is becoming apparent that weather and storms had little to do with the scenario. You can pick up ice crystals during a protracted cruise in smooth CirroStratus. That there was some weather around was not unusual for the ITCZ.