From HN39:
A propos stall warning. In Interim Report #2 BEA explains that stall warning starts when the AoA exceeds approx. 10 degrees at M=0.3, and at approx. 4 degrees at M=0.8. The update now provides a third datapoint of 6 degrees at M=0,633 (extrapolated backwards from 185 kt 15 seconds later). These points relate to alphamax as shown in this graph.
That shows neatly how Stall Warning incidence is a function of Mach Number, so when the ADRs went belly up, what happened to the M input to the stall warning system, and what did the latter think the corresponding warning incidence (AOA) should be? Does it use the last valid IAS/M value as the rudder limiter system does?
Secondly the BEA states that right at the start of the sequence :
From 2 h 10 min 05 , the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row.
Does anyone know why the warning sounded at this stage? It's not obvious. Could it have been an indication of moderate or worse turbulence, because, after all, this was before the dramatic and inexplicable zoom climb, and before the sustained nose up side stick inputs that caused the THS to reach 13 deg airplane nose up? The aircraft should have been in a normal cruise condition at this earlier stage. Among lots of things the BEA hasn't chosen to reveal yet, is the general level of turbulence experienced before and during the upset. For that matter they haven't said whether there were any stall warnings before it all went wrong.
Note that in the Air Caraibes blocked pitot event they also reported a 10 second stall warning about 30 secs after the AP disconnect and start of the general brouhaha. The crew decided this was false, in accordance with advice in the <<ADR CHECK PROC>>, though the ACA report notes that elsewhere the crew are told to ignore that advice and respect the stall warnings. Confused? Those issues don't seem to have been resolved, at least not in readily available documents or posts here.