AC 4121 then AC 4154 at San Francisco
Ontario → San Francisco → Tucson
Timetable, San Francisco time
17:50AC 4121 from Ontario at the gate
12:10AC 4154 to Tucson leaves the gatealso UA 5736, NH 7008, NZ 9748
18 h 20 apart on the timetable, overnight
AC 4154 leaves 18 h 20 after AC 4121 arrives on the timetable: more than half a day, so not a connection we count.