BA 480 then QR 3591 at Barcelona
London Heathrow → Barcelona → Catania
Timetable, Barcelona time
13:45BA 480 from London Heathrow at the gatealso IB 3662, QR 6297, AA 6818, VY 9558
11:00QR 3591 to Catania leaves the gatealso IB 5802, LL 5802, VY 6118
21 h 15 apart on the timetable, overnight
QR 3591 leaves 21 h 15 after BA 480 arrives on the timetable: more than half a day, so not a connection we count.