UA 4500 then OS 42 at Dulles
Detroit → Washington → Vienna
Timetable, Washington time
21:17UA 4500 from Detroit at the gate
18:00OS 42 to Vienna leaves the gate
20 h 43 apart on the timetable, overnight
OS 42 leaves 20 h 43 after UA 4500 arrives on the timetable: more than half a day, so not a connection we count.