Did mine with BASP (British Association of Ski Patrollers).
The knot tying took about 2 seconds, does it work, yes, move on.
Brilliant outdoor secenario role play and lots of, if you found this bloke wrapped round a tree and his bike down there what would you do (strip his bike and leave him for dead is not an acceptable answer, apparently)?
Mind you i did mine at Glenmore Lodge although i guess BASP will do them where there are ski areas.