UA 271 then AV 2354 at San Francisco
Washington → San Francisco → Denver
Timetable, San Francisco time
12:32UA 271 from Washington at the gatealso NZ 9180
05:00AV 2354 to Denver leaves the gate
16 h 28 apart on the timetable, overnight
AV 2354 leaves 16 h 28 after UA 271 arrives on the timetable: more than half a day, so not a connection we count.