BA 1399 then BA 398 at Heathrow
Belfast City → London → Cairo
Timetable, London time
16:10BA 1399 from Belfast City at the gate
16:05BA 398 to Cairo leaves the gate
23 h 55 apart on the timetable, overnight
BA 398 leaves 23 h 55 after BA 1399 arrives on the timetable: more than half a day, so not a connection we count.