On 2007-02-07, BDS wrote:
I didn't listen to the tape but the descriptions that mentioned a sudden out
of control dive sure sound like a tailplane stall to me. It can take a
tremendous amount of force on the yoke to recover, and recovery technique is
not intuitive because it is not the same as the technique(s) used for a
normal wing stall.

Other nasty things can happen in icing too. You may remember the
incident with the ATR in Roselawn, Indiana (which has a substantially
similar airfoil to a Caravan, I'd imagine). Ice built up behind the
area behind the deicing boots in a ridge. The aircraft was on autopilot.
When the autopilot disconnected, the ailerons underwent a "hinge moment
reversal" - so instead of wanting to remain neutral, snapped to full
control deflection very suddenly. The plane went inverted, and the crew
split-S'd out of it. Unfortunately, the aircraft disintegrated during
the split S from the G forces.

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