AC 4121 then UA 2803 at San Francisco
Ontario → San Francisco → Denver
Timetable, San Francisco time
17:50AC 4121 from Ontario at the gate
13:00UA 2803 to Denver leaves the gatealso AC 4049, CA 7309, NH 7310, VA 8338, NZ 9056
19 h 10 apart on the timetable, overnight
UA 2803 leaves 19 h 10 after AC 4121 arrives on the timetable: more than half a day, so not a connection we count.