AA 4521 then B6 8439 at Boston
Rochester → Boston → New York JFK
Timetable, Boston time
06:30AA 4521 from Rochester at the gate
14:00B6 8439 to New York JFK leaves the gate
7 h 30 apart on the timetable
The last days
AA 4521 and B6 8439 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.