UA 4500 then VS 22 at Dulles
Detroit → Washington → London
Timetable, Washington time
21:17UA 4500 from Detroit at the gate
18:55VS 22 to London leaves the gate
21 h 38 apart on the timetable, overnight
VS 22 leaves 21 h 38 after UA 4500 arrives on the timetable: more than half a day, so not a connection we count.