UA 3874 then UA 3 at O'Hare
Chicago Rockford → Chicago → Zurich
Timetable, Chicago time
01:21UA 3874 from Chicago Rockford at the gate
16:10UA 3 to Zurich leaves the gate
14 h 49 apart on the timetable
UA 3 leaves 14 h 49 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.