OO 9909 then UA 5815 at O'Hare
Waterloo → Chicago → Lexington
Timetable, Chicago time
16:47OO 9909 from Waterloo at the gate
10:35UA 5815 to Lexington leaves the gate
17 h 48 apart on the timetable, overnight
UA 5815 leaves 17 h 48 after OO 9909 arrives on the timetable: more than half a day, so not a connection we count.