I've traveled on flights frequently for over a decade, and I've never had an airline refuse to seat me for a flight I had a ticket for. I don't use frequent-flyer, and just buy the cheapest tickets available on Expedia. The only saving grace I can think of is that I always get to the airport way before anyone else does. Have I just been getting lucky all this time? Short of being a frequent flyer or buying expensive tickets, is there any way I can make sure I don't get bumped off a plane I have tickets for?