OO 9909 then UA 1239 at O'Hare
Waterloo → Chicago → Rochester (ROC)
Timetable, Chicago time
16:47OO 9909 from Waterloo at the gate
13:55UA 1239 to Rochester (ROC) leaves the gate
21 h 08 apart on the timetable, overnight
UA 1239 leaves 21 h 08 after OO 9909 arrives on the timetable: more than half a day, so not a connection we count.