Andy,

Let me reduce my original question to a specific situation. Suppose
you're flying in 60 degree weather, so no surface is contaminated with
ice. Suddenly, the nose pitches down and the stick stays where it
was.

My question is: how do you know if you've suffered a wing stall (where
the recovery is to push the stick forward), or a tail stall (where the
recovery is to pull the stick back).

-John

On Feb 20, 1:13 pm, Andy wrote:
I hate to risk adding to the obvious confususion but....

The NASA video deals with a specific case where a contamined tail
results in a uncommanded sudden downward motion of the elevator, which
in turn results in a forward stick motion, and a nose down pitch.

The situation would appear to be completely different from an
aerodynamic stall of an uncontaminated tail surface.

The use of the term "tail stall" for the icing induced pitch down
seems misleading to me since the tailplane could not be at critical
angle of attack if returning the elevator to its pre-displaced
position restores the downward tail force.

A significant difference between the two scenarios is the stick
motion associated with the event. Iced up tail - nose pitches down
as stick moves forward. Aerodynamic tail stall - nose pitches down
as stick moves aft or stay where it was.

Linking to the thread on stall awareness and recovery, the iced tail
situation that results in down elevator and uncommanded forward stick
motion may be hard to distinguish from a stick pusher event, and the
required recovery for these is exactly opposite.

Andy