AA 5490 then UA 1279 at Dulles
Charlotte → Washington → Boston
Timetable, Washington time
08:44AA 5490 from Charlotte at the gate
15:00UA 1279 to Boston leaves the gate
6 h 16 apart on the timetable
The last days
AA 5490 and UA 1279 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.