BA 809 then UA 928 at Heathrow
Copenhagen → London → Chicago
Timetable, London time
13:55BA 809 from Copenhagen at the gate
13:35UA 928 to Chicago leaves the gate
23 h 40 apart on the timetable, overnight
UA 928 leaves 23 h 40 after BA 809 arrives on the timetable: more than half a day, so not a connection we count.