VS 21 then UA 4055 at Dulles
London → Washington → Louisville
Timetable, Washington time
17:40VS 21 from London at the gate
17:35UA 4055 to Louisville leaves the gate
23 h 55 apart on the timetable, overnight
UA 4055 leaves 23 h 55 after VS 21 arrives on the timetable: more than half a day, so not a connection we count.