AA 640 then UA 445 at Denver
Charlotte → Denver → Boston
Timetable, Denver time
13:27AA 640 from Charlotte at the gate
17:56UA 445 to Boston leaves the gate
4 h 29 apart on the timetable
The last days
AA 640 and UA 445 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.