UA 3874 then AA 3053 at O'Hare
Chicago → Chicago → Indianapolis
Timetable, Chicago time
01:21UA 3874 from Chicago at the gate
17:27AA 3053 to Indianapolis leaves the gate
16 h 06 apart on the timetable
AA 3053 leaves 16 h 06 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.