PR 3897 then UA 2278 at San Francisco
Los Angeles → San Francisco → Chicago O'Hare
Timetable, San Francisco time
18:02PR 3897 from Los Angeles at the gate
22:45UA 2278 to Chicago O'Hare leaves the gate
4 h 43 apart on the timetable
The last days
PR 3897 and UA 2278 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.