IB 724 then CX 1751 at Madrid
London Heathrow → Madrid → Buenos Aires
Timetable, Madrid time
22:35IB 724 from London Heathrow at the gatealso LA 1543, VY 5187, QR 6589, BA 7065, AA 8770
12:20CX 1751 to Buenos Aires leaves the gatealso BA 4255, AY 5375
13 h 45 apart on the timetable, overnight
CX 1751 leaves 13 h 45 after IB 724 arrives on the timetable: more than half a day, so not a connection we count.