AA 4504 then OO 391 at O'Hare
South Bend → Chicago → Detroit
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
14:30OO 391 to Detroit leaves the gatealso UA 391
19 h 55 apart on the timetable, overnight
OO 391 leaves 19 h 55 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.