AA 1138 then UA 5539 at O'Hare
Atlanta → Chicago → Cleveland
Timetable, Chicago time
18:10AA 1138 from Atlanta at the gate
10:50UA 5539 to Cleveland leaves the gate
16 h 40 apart on the timetable, overnight
UA 5539 leaves 16 h 40 after AA 1138 arrives on the timetable: more than half a day, so not a connection we count.