BA 349 then BA 191 at Heathrow
Nice → London → Austin
Timetable, London time
21:05BA 349 from Nice at the gate
12:10BA 191 to Austin leaves the gate
15 h 05 apart on the timetable, overnight
BA 191 leaves 15 h 05 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.