UA 3909 then UA 580 at San Francisco
Houston → San Francisco → Los Angeles
Timetable, San Francisco time
07:17UA 3909 from Houston at the gate
21:20UA 580 to Los Angeles leaves the gatealso CM 1067, VA 8560, NZ 9258
14 h 03 apart on the timetable
UA 580 leaves 14 h 03 after UA 3909 arrives on the timetable: more than half a day, so not a connection we count.