BA 1395 then BA 223 at Heathrow
Belfast City → London → Nashville
Timetable, London time
13:15BA 1395 from Belfast City at the gate
13:10BA 223 to Nashville leaves the gate
23 h 55 apart on the timetable, overnight
BA 223 leaves 23 h 55 after BA 1395 arrives on the timetable: more than half a day, so not a connection we count.