UA 3873 then AA 6284 at O'Hare
Fort Worth → Chicago → Des Moines
Timetable, Chicago time
17:55UA 3873 from Fort Worth at the gate
07:14AA 6284 to Des Moines leaves the gate
13 h 19 apart on the timetable, overnight
AA 6284 leaves 13 h 19 after UA 3873 arrives on the timetable: more than half a day, so not a connection we count.