AA 153 then AA 772 at O'Hare
Charlotte → Chicago → St Louis
Timetable, Chicago time
11:42AA 153 from Charlotte at the gate
18:03AA 772 to St Louis leaves the gate
6 h 21 apart on the timetable
The last days
AA 153 and AA 772 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.