B6 837 then DL 5491 at Detroit
Boston → Detroit → Louisville
Timetable, Detroit time
11:19B6 837 from Boston at the gate
15:50DL 5491 to Louisville leaves the gate
4 h 31 apart on the timetable
The last days
B6 837 and DL 5491 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.