UA 8173 then AA 5519 at O'Hare
Cleveland → Chicago → Louisville
Timetable, Chicago time
10:54UA 8173 from Cleveland at the gate
14:42AA 5519 to Louisville leaves the gate
3 h 48 apart on the timetable
The last days
UA 8173 and AA 5519 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.