IB 722 then CX 1751 at Madrid
London Heathrow → Madrid → Buenos Aires
Timetable, Madrid time
22:10IB 722 from London Heathrow at the gatealso LA 1541, VY 5227, DT 6171, QR 6943, BA 7061
11:45CX 1751 to Buenos Aires leaves the gatealso BA 4255, AY 5375
13 h 35 apart on the timetable, overnight
CX 1751 leaves 13 h 35 after IB 722 arrives on the timetable: more than half a day, so not a connection we count.