UA 511 then ET 3511 at O'Hare
Washington National → Chicago → Muscat
Timetable, Chicago time
14:26UA 511 from Washington National at the gate
09:05ET 3511 to Muscat leaves the gate
18 h 39 apart on the timetable, overnight
ET 3511 leaves 18 h 39 after UA 511 arrives on the timetable: more than half a day, so not a connection we count.