just gotta dig the front end down a bit or get the rear on some fresh snow. they dont get stuck easily.
heres a good video showing how much of a beast these things are.
http://www.youtube.com/watch?v=cCh59r-1RyQ
only reason i got stuck up there was the ski got caught in that barrel. and the track dug all the way down to the ground (4+ feet) giving it no snow to bite.