AA 1509 then DL 712 at Atlanta
Cleveland → Atlanta → San Diego
Timetable, Atlanta time
09:08AA 1509 from Cleveland at the gate
17:59DL 712 to San Diego leaves the gate
8 h 51 apart on the timetable
The last days
AA 1509 and DL 712 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.