I wore my Crocs on a flight last month. In fact, I'll be wearing them again next month for our Disney trip. They are very easy to get off and on at the x-ray machine - nothing to tie, buckle, etc. Crocs do not have gel in them at all so there are "legal." If you have gel inserts in your shoes (i.e. the Dr. Scholl inserts you buy and put in your sneakers), you have to put them in your checked bag. They're not allowed through security.