DL 5684 then DL 9899 at Boston
Cleveland → Boston → New York JFK
Timetable, Boston time
08:02DL 5684 from Cleveland at the gate
12:00DL 9899 to New York JFK leaves the gate
3 h 58 apart on the timetable
The last days
DL 5684 and DL 9899 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.