BA 52 then BA 638 at Heathrow
Seattle → London → Athens
Timetable, London time
07:10BA 52 from Seattle at the gate
16:15BA 638 to Athens leaves the gate
9 h 05 apart on the timetable
The last days
BA 52 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.