TK 1989 then BA 1408 at Heathrow
Istanbul → London → Belfast City
Timetable, London time
14:15TK 1989 from Istanbul at the gate
18:10BA 1408 to Belfast City leaves the gate
3 h 55 apart on the timetable
The last days
TK 1989 and BA 1408 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.