UA 4528 then AA 9785 at O'Hare
St Louis → Chicago → Philadelphia
Timetable, Chicago time
14:39UA 4528 from St Louis at the gate
21:00AA 9785 to Philadelphia leaves the gate
6 h 21 apart on the timetable
The last days
UA 4528 and AA 9785 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.