UA 821 then AA 3176 at LAX
Hong Kong → Los Angeles → San Francisco
Timetable, Los Angeles time
19:30UA 821 from Hong Kong at the gate
12:37AA 3176 to San Francisco leaves the gate
17 h 07 apart on the timetable, overnight
AA 3176 leaves 17 h 07 after UA 821 arrives on the timetable: more than half a day, so not a connection we count.