UA 2747 then CV 12 at O'Hare
Buffalo → Chicago → Luxembourg
Timetable, Chicago time
19:02UA 2747 from Buffalo at the gate
14:55CV 12 to Luxembourg leaves the gate
19 h 53 apart on the timetable, overnight
CV 12 leaves 19 h 53 after UA 2747 arrives on the timetable: more than half a day, so not a connection we count.