UA 3902 then UA 5821 at O'Hare
London → Chicago → Milwaukee
Timetable, Chicago time
14:15UA 3902 from London at the gate
09:02UA 5821 to Milwaukee leaves the gate
18 h 47 apart on the timetable, overnight
UA 5821 leaves 18 h 47 after UA 3902 arrives on the timetable: more than half a day, so not a connection we count.