AA 2142 then AA 3247 at Miami
Seattle → Miami → Boston
Timetable, Miami time
06:00AA 2142 from Seattle at the gate
09:55AA 3247 to Boston leaves the gate
3 h 55 apart on the timetable
The last days
AA 2142 and AA 3247 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.