AA 642 then UA 1778 at O'Hare
Dallas-Fort Worth → Chicago → Omaha
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
08:41UA 1778 to Omaha leaves the gate
19 h 31 apart on the timetable, overnight
UA 1778 leaves 19 h 31 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.