AC 4121 then UA 520 at San Francisco
Ontario → San Francisco → Tampa
Timetable, San Francisco time
17:50AC 4121 from Ontario at the gate
12:00UA 520 to Tampa leaves the gate
18 h 10 apart on the timetable, overnight
UA 520 leaves 18 h 10 after AC 4121 arrives on the timetable: more than half a day, so not a connection we count.