UA 3874 then OO 435 at O'Hare
Chicago → Chicago → Oklahoma City
Timetable, Chicago time
01:21UA 3874 from Chicago at the gate
13:30OO 435 to Oklahoma City leaves the gate
12 h 09 apart on the timetable
OO 435 leaves 12 h 09 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.