B6 8622 then GF 6604 at JFK
Fort Worth → New York → London Heathrow
Timetable, New York time
15:58B6 8622 from Fort Worth at the gate
21:45GF 6604 to London Heathrow leaves the gate
5 h 47 apart on the timetable
The last days
B6 8622 and GF 6604 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.