DL 1558 then DL 934 at Detroit
Washington National → Detroit → New York JFK
Timetable, Detroit time
11:22DL 1558 from Washington National at the gate
19:00DL 934 to New York JFK leaves the gate
7 h 38 apart on the timetable
The last days
DL 1558 and DL 934 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.