Attitude + Power = Performance Not Valid for Stall Recovery
AF447 has contributed substantial hindsight on this situation.
Three pilots over three minutes could not identify the stall problem; they thought they had another problem, likely overspeed, and were trying to solve that one.
It seems the VSI indication was dismissed.
But they did identify decreasing altitude at 9000 and 8000 and became rightly concerned. At that time the fifth digit had dropped from view. Perhaps that got their attention.
How is it that the altimeter display did not get their attention earlier?
As has been mentioned, on a round altimeter the winding hands would be quite obvious.
But an abnormal descent rate on a flat panel display does not grab the pilots' attention as well as a round altimeter.
Should we be coloring the altitude display red or orange for abnormal descent rates?