United.com is a bit confusing on this, so I just want to make sure. My understanding is that I can standby for a later flight and pay a $75 change fee (assuming non-refundable ticket and no status), but won't be asked to pay a fare difference. The good old days of getting to the airport late due to traffic and being put on a later flight for free are long gone. Is this correct? What if I cannot tell them in advance that I would be late, for example because I'm on another flight with no way to communicate? I think elsewhere they say that you forfeit your ticket if you don't cancel before departure...? Thanks in advance for clearing this up!