UA 1905 then UA 1665 at San Francisco
Los Angeles → San Francisco → Boston
Timetable, San Francisco time
11:17UA 1905 from Los Angeles at the gatealso VA 8554, NZ 9282
23:20UA 1665 to Boston leaves the gatealso VA 8306, NZ 9018
12 h 03 apart on the timetable
UA 1665 leaves 12 h 03 after UA 1905 arrives on the timetable: more than half a day, so not a connection we count.