Let's try and take this a piece at a time:
Beginning of the incident (first 11 seconds) -
"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. The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS)."
- I would expect pitot icing to be a gradual process. Why is there a "sharp fall" of 215 kts in IAS at this point?
I don't doubt the probes were iced, I'm just wondering how that alone would drop the indicated speed so rapidly. If the pitots are blocked, this is not a "real" speed change, correct?
If the pitots are blocked and trapping pressure, a climb should result in an increase in indicated speed as static pressure drops. Correct? (That is not apparently what happened).
If the pitots are blocked, a descent would result in a drop in indicated speed as static pressure increases. Correct?