UA 4345 then DL 951 at Detroit
Washington → Detroit → New York JFK
Timetable, Detroit time
10:19UA 4345 from Washington at the gate
19:01DL 951 to New York JFK leaves the gate
8 h 42 apart on the timetable
The last days
UA 4345 and DL 951 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.