AS 634 then UA 901 at San Francisco
Las Vegas → San Francisco → London
Timetable, San Francisco time
17:41AS 634 from Las Vegas at the gatealso QF 3697, FJ 5841, AA 7412, CX 7935, QR 8861
12:50UA 901 to London leaves the gatealso LX 3069, AC 5448, OS 7856, SN 9105, LH 9375, NZ 9830
19 h 09 apart on the timetable, overnight
UA 901 leaves 19 h 09 after AS 634 arrives on the timetable: more than half a day, so not a connection we count.