DL 5604 then DL 9974 at Boston
Memphis → Boston → Atlanta
Timetable, Boston time
10:03DL 5604 from Memphis at the gate
14:00DL 9974 to Atlanta leaves the gate
3 h 57 apart on the timetable
The last days
DL 5604 and DL 9974 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.