DL 8839 then DL 5441 at Detroit
Philadelphia → Detroit → Louisville
Timetable, Detroit time
02:33DL 8839 from Philadelphia at the gate
08:35DL 5441 to Louisville leaves the gate
6 h 02 apart on the timetable
The last days
DL 8839 and DL 5441 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.