AA 2163 then UA 3395 at O'Hare
Hartford → Chicago → St Louis
Timetable, Chicago time
09:05AA 2163 from Hartford at the gate
13:00UA 3395 to St Louis leaves the gate
3 h 55 apart on the timetable
The last days
AA 2163 and UA 3395 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.