AV 2104 then UA 8172 at San Francisco
San Luis Obispo → San Francisco → Boston
Timetable, San Francisco time
19:56AV 2104 from San Luis Obispo at the gate
12:45UA 8172 to Boston leaves the gate
16 h 49 apart on the timetable, overnight
UA 8172 leaves 16 h 49 after AV 2104 arrives on the timetable: more than half a day, so not a connection we count.