AF 447 Elevator trim
Is there a determination of how the elevator trim came to be so high, nose up? The trim has more authority than the elevator and I doubt it is possible to recover from a deep stall with the trim full, or nearly full, in the nose up condition. My reading of the Airbus control laws is that automatic pitch trim is "available" in the Alternate Law mode. Did the trim go to the nose up position from pilot input or is there some envelope protection or other reason for it?
In the jet upset cases, it is hypothesized, that an updraft or headwind increase from penetrating an upper frontal boundary caused the aircraft to pitch up; the pilot pushed over but also trimmed nose down then the aircraft developed a steep descent with the pilot pulling hard to resist; the elevator force was sufficient to jam the elevator trim jackscrew so nose up trim could not be accomplished; the aircraft developed a steep dive which could not be corrected. Is it possible in this case, the pilots were attempting to cause a nose down condition and the elevator force was sufficient to jam the elevator trim?
There is a dynamic stall condition, discussed by S.S. Horner in his book on Fluid Dynamics where the AOA at which airflow re-attaches to the upper surface of the wing is significantly less than the AOA at initial stall.