DL 3082 then DL 5815 at Dulles
Detroit → Washington → New York JFK
Timetable, Washington time
11:34DL 3082 from Detroit at the gate
18:20DL 5815 to New York JFK leaves the gate
6 h 46 apart on the timetable
The last days
DL 3082 and DL 5815 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.