AA 642 then UA 1643 at O'Hare
Dallas-Fort Worth → Chicago → Orlando
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
09:05UA 1643 to Orlando leaves the gate
19 h 55 apart on the timetable, overnight
UA 1643 leaves 19 h 55 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.