KL 1000 then KL 1985 at Schiphol
London Heathrow → Amsterdam → Belgrade
Timetable, Amsterdam time
09:00KL 1000 from London Heathrow at the gate
21:15KL 1985 to Belgrade leaves the gate
12 h 15 apart on the timetable
KL 1985 leaves 12 h 15 after KL 1000 arrives on the timetable: more than half a day, so not a connection we count.