AA 2146 then UA 2723 at O'Hare
Boston → Chicago → Omaha
Timetable, Chicago time
08:00AA 2146 from Boston at the gate
20:10UA 2723 to Omaha leaves the gate
12 h 10 apart on the timetable
UA 2723 leaves 12 h 10 after AA 2146 arrives on the timetable: more than half a day, so not a connection we count.