The 1976 Zagreb mid-air collision occurred on 10 September 1976 when British Airways Flight 476, a Hawker Siddeley Trident 3B en route from London Heathrow Airport to Ye ilköy International Airport, Istanbul, collided in mid-air with Inex-Adria Aviopromet Flight 550, a Douglas DC-9 en route from Split Ka tela/Resnik Airport, Croatia, to Cologne Bonn Airport, West Germany, at 11:15am local time (10:15 UTC). All 176 people aboard both flights were killed making it, at the time, the world's deadliest mid-air collision; it had a death toll higher than that of All Nippon Airways Flight 58. It was, and remains, the only fatal accident to befall an aircraft operated by British Airways.