BA 349 then BA 171 at Heathrow
Nice → London → Pittsburgh
Timetable, London time
21:05BA 349 from Nice at the gate
15:55BA 171 to Pittsburgh leaves the gate
18 h 50 apart on the timetable, overnight
BA 171 leaves 18 h 50 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.