AA 9866 then AA 3462 at O'Hare
Marquette → Chicago → Hilton Head
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
10:00AA 3462 to Hilton Head leaves the gate
23 h 30 apart on the timetable, overnight
AA 3462 leaves 23 h 30 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.