BA 349 then UA 15 at Heathrow
Nice → London → Newark
Timetable, London time
21:05BA 349 from Nice at the gate
15:10UA 15 to Newark leaves the gate
18 h 05 apart on the timetable, overnight
UA 15 leaves 18 h 05 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.