UA 6239 then AA 5643 at Charlotte
Washington → Charlotte → Savannah
Timetable, Charlotte time
14:22UA 6239 from Washington at the gate
14:06AA 5643 to Savannah leaves the gate
23 h 44 apart on the timetable, overnight
AA 5643 leaves 23 h 44 after UA 6239 arrives on the timetable: more than half a day, so not a connection we count.