Originally Posted by IceTrojan
I don't know about trying for a standby flight, but the general rule is that if you don't cancel your tix before your scheduled flight, you lose the value of the fare... you have to tell AA before your flight takes off.
Right, and by requesting the standby on a later flight, you are de facto telling AA you are cancelling your originally-scheduled flight, hence preserving the value of the ticket (less any change fee). So I still don't get how the ticket expires, as two other posters claim.