AA 3546 then AA 1779 at Boston
St Louis → Boston → Washington National
Timetable, Boston time
13:44AA 3546 from St Louis at the gate
19:58AA 1779 to Washington National leaves the gate
6 h 14 apart on the timetable
The last days
AA 3546 and AA 1779 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.