UA 3851 then BA 284 at San Francisco
Rio De Janeiro → San Francisco → London
Timetable, San Francisco time
17:41UA 3851 from Rio De Janeiro at the gate
17:25BA 284 to London leaves the gatealso IB 3625, AS 5278, AY 5524, AA 6995, EI 8984
23 h 44 apart on the timetable, overnight
BA 284 leaves 23 h 44 after UA 3851 arrives on the timetable: more than half a day, so not a connection we count.