AA 2282 then UA 639 at Denver
Philadelphia → Denver → Los Angeles
Timetable, Denver time
11:22AA 2282 from Philadelphia at the gate
15:59UA 639 to Los Angeles leaves the gate
4 h 37 apart on the timetable
The last days
AA 2282 and UA 639 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.