Mike Ash wrote:

James Robinson wrote:

When the flaps are extended, and a tailplane stall results, the
aircraft immediately pitches down. There is no stall warning or
stick shaker activation.

In the case of the Buffalo accident, the nose did not drop, but the
stick shaker activated shortly after the flap setting was made. The
stick shaker is fired by low air speed, and is only a warning of
impending wing stall, with some airspeed margin. It is not an
indication of tailplane stall, or of an actual wing stall.
Therefore, the correct action when the stick shaker fired should have
been to push the nose down to keep speed up and reduce AOA. No
question.

Further, the Q400 supposedly will never see a tailplane stall in
icing, but the crew may not have known that. The Saabs the captain
previously flew are subject to tailplane stall in icing, and he might
have reacted based on his previous training and apprehension about
such stalls.

Ah hah, that makes sense. Given that the stick shaker had activated,
they should have known it was a regular stall and performed a regular
recovery. A tail stall would have happened abruptly with no stick
shaker. Is that about right? Makes sense if so.

The FDR data shows the following happening in quick sequence:

- Ice warning showing up on display for first time
- Flap handle setting increased
- Stick shaker activated

The flaps had only extended about 1 or 2 degrees when the stick shaker
fired, but was the crew somehow influenced by the ice warning and the
fact that the flaps setting had just been changed? They certainly took
the wrong action in response to the stick shaker. Why?