VS 21 then UA 1869 at Dulles
London → Washington → San Antonio
Timetable, Washington time
17:40VS 21 from London at the gate
17:30UA 1869 to San Antonio leaves the gate
23 h 50 apart on the timetable, overnight
UA 1869 leaves 23 h 50 after VS 21 arrives on the timetable: more than half a day, so not a connection we count.