AA 2851 then AA 2054 at O'Hare
Denver → Chicago → Boston
Timetable, Chicago time
10:30AA 2851 from Denver at the gate
11:00AA 2054 to Boston leaves the gate
30 min apart on the timetable
The last days
AA 2851 and AA 2054 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.