AA 2129 then AA 880 at Philadelphia
Miami → Philadelphia → Chicago O'Hare
Timetable, Philadelphia time
09:45AA 2129 from Miami at the gate
10:40AA 880 to Chicago O'Hare leaves the gate
55 min apart on the timetable
The last days
AA 2129 and AA 880 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.