Here's a video from NASA about tailplane icing, which may well have caused the recent crash in the USA. Check out at about 11:00 where they take an aircraft up with bits of foam strapped to the hori stab to simulate icing. at 13:00 minutes they tell you not to try this yourself and about 15:00 they experience a full blown tail stall.
Good thing for all us to watch methinks..
http://video.google.com/videoplay?docid=2238323060735779946
