AA 1277 then AA 4480 at O'Hare
Denver → Chicago → Louisville
Timetable, Chicago time
18:19AA 1277 from Denver at the gate
19:00AA 4480 to Louisville leaves the gate
41 min apart on the timetable
The last days
AA 1277 and AA 4480 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.