AA 2363 then UA 545 at O'Hare
Denver → Chicago → Philadelphia
Timetable, Chicago time
16:00AA 2363 from Denver at the gate
19:45UA 545 to Philadelphia leaves the gate
3 h 45 apart on the timetable
The last days
AA 2363 and UA 545 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.