We arrived at the airport (CLT) to try to get on earlier flight this past sunday (about 25 minutes before that flight was to take off.

Got to ticket counter and agent asked us if we were checking any luggage...My dad was and after she clicked on her keys for a while she told him that she COULD check his luggage because the gate (i think she said gate) hadn't done a "last call".

It worked out wonderfull...we got to airport that close to flight time, I got platinum upgrade and my dad got companion upgrade and plane was FULL.