BR 646 then UA 638 at O'Hare
Anchorage → Chicago → San Francisco
Timetable, Chicago time
17:10BR 646 from Anchorage at the gate
12:42UA 638 to San Francisco leaves the gate
19 h 32 apart on the timetable, overnight
UA 638 leaves 19 h 32 after BR 646 arrives on the timetable: more than half a day, so not a connection we count.