BA 1182 then BA 638 at Heathrow
New York JFK → London → Athens
Timetable, London time
11:10BA 1182 from New York JFK at the gate
17:35BA 638 to Athens leaves the gate
6 h 25 apart on the timetable
The last days
BA 1182 and BA 638 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.