AA 1809 then AA 866 at Boston
Charlotte → Boston → Chicago O'Hare
Timetable, Boston time
12:35AA 1809 from Charlotte at the gate
13:30AA 866 to Chicago O'Hare leaves the gate
55 min apart on the timetable
Boston’s board gives an arrival time for only about 58% of its flights, so many days show no gate time.
The last days
AA 1809 and AA 866 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.