AA 6276 then BA 1782 at San Francisco
Phoenix → San Francisco → Chicago O'Hare
Timetable, San Francisco time
10:03AA 6276 from Phoenix at the gatealso QR 9504
14:18BA 1782 to Chicago O'Hare leaves the gatealso AA 1948, AY 4140
4 h 15 apart on the timetable
The last days
AA 6276 and BA 1782 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.