UA 938 then BA 964 at Heathrow
Chicago → London → Hamburg
Timetable, London time
12:00UA 938 from Chicago at the gate
11:30BA 964 to Hamburg leaves the gate
23 h 30 apart on the timetable, overnight
BA 964 leaves 23 h 30 after UA 938 arrives on the timetable: more than half a day, so not a connection we count.