AA 880 then UA 3872 at O'Hare
Philadelphia → Chicago → LCQ
Timetable, Chicago time
12:19AA 880 from Philadelphia at the gate
00:31UA 3872 to LCQ leaves the gate
12 h 12 apart on the timetable, overnight
UA 3872 leaves 12 h 12 after AA 880 arrives on the timetable: more than half a day, so not a connection we count.