AA 2748 then ET 3511 at O'Hare
Las Vegas → Chicago → Muscat
Timetable, Chicago time
20:07AA 2748 from Las Vegas at the gate
09:05ET 3511 to Muscat leaves the gate
12 h 58 apart on the timetable, overnight
ET 3511 leaves 12 h 58 after AA 2748 arrives on the timetable: more than half a day, so not a connection we count.