AA 5510 then DL 1251 at Atlanta
Washington National → Atlanta → Tucson
Timetable, Atlanta time
23:23AA 5510 from Washington National at the gate
20:59DL 1251 to Tucson leaves the gate
21 h 36 apart on the timetable, overnight
DL 1251 leaves 21 h 36 after AA 5510 arrives on the timetable: more than half a day, so not a connection we count.