AA 9911 then UA 5811 at O'Hare
Des Moines → Chicago → Flint
Timetable, Chicago time
19:30AA 9911 from Des Moines at the gate
15:35UA 5811 to Flint leaves the gate
20 h 05 apart on the timetable, overnight
UA 5811 leaves 20 h 05 after AA 9911 arrives on the timetable: more than half a day, so not a connection we count.