I have done it several times from ORD with checked bags. After arriving from an international flight, the bag is in hand, and has to be *secured* by TSA before going back on the belt. I just check at the counter to see if there is and earlier flight available and if so, my bag is tagged for standby right there.
Edited to add:
Originally Posted by hillrider
The ability to standby for an earlier flight is determined by the fare you hold.
Is this a new policy for AA? I have never been told that standby elgibility depends on fare. And I have stoodby on a lot of cheap tickets.