BA 1399 then AY 1336 at Heathrow
Belfast City → London → Helsinki
Timetable, London time
16:35BA 1399 from Belfast City at the gate
16:15AY 1336 to Helsinki leaves the gate
23 h 40 apart on the timetable, overnight
AY 1336 leaves 23 h 40 after BA 1399 arrives on the timetable: more than half a day, so not a connection we count.