DL 1540 then DL 8925 at Detroit
Philadelphia → Detroit → Washington
Timetable, Detroit time
07:50DL 1540 from Philadelphia at the gate
14:00DL 8925 to Washington leaves the gate
6 h 10 apart on the timetable
The last days
DL 1540 and DL 8925 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.