AC 4121 then WN 2989 at San Francisco
Ontario → San Francisco → St Louis
Timetable, San Francisco time
17:50AC 4121 from Ontario at the gatealso UA 5483
13:05WN 2989 to St Louis leaves the gate
19 h 15 apart on the timetable, overnight
WN 2989 leaves 19 h 15 after AC 4121 arrives on the timetable: more than half a day, so not a connection we count.