UA 3870 then UA 2278 at San Francisco
Xiamen → San Francisco → Chicago O'Hare
Timetable, San Francisco time
07:49UA 3870 from Xiamen at the gate
22:45UA 2278 to Chicago O'Hare leaves the gatealso VA 8105
14 h 56 apart on the timetable
UA 2278 leaves 14 h 56 after UA 3870 arrives on the timetable: more than half a day, so not a connection we count.