AA 4504 then UA 455 at O'Hare
South Bend → Chicago → Phoenix
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
12:55UA 455 to Phoenix leaves the gate
18 h 20 apart on the timetable, overnight
UA 455 leaves 18 h 20 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.