AA 3199 then UA 8219 at San Francisco
Phoenix → San Francisco → Chicago O'Hare
Timetable, San Francisco time
14:01AA 3199 from Phoenix at the gate
18:10UA 8219 to Chicago O'Hare leaves the gate
4 h 09 apart on the timetable
The last days
AA 3199 and UA 8219 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.