K4 551 then UA 646 at O'Hare
Anchorage → Chicago → Denver
Timetable, Chicago time
16:28K4 551 from Anchorage at the gate
13:30UA 646 to Denver leaves the gate
21 h 02 apart on the timetable, overnight
UA 646 leaves 21 h 02 after K4 551 arrives on the timetable: more than half a day, so not a connection we count.