Originally Posted by
bocastephen
you cannot ignore your ticket and let it go past departure time or that is a no-show and UA has no obligation to do anything for you.
If a flight is cancelled, no-show penalties don't apply. (You can't no-show a flight that didn't take off). However, I agree that if you want to cancel a ticket on a flight that's operating, you'll want to do it prior to departure, and budget 60+ minutes for hold time unless you have Premier status.