A Douglas DC-6B passenger plane (SE-BDA) operated by Scandinavian Airlines System and an Avro 685 York transport plane (MW248) operated by the Royal Air Force both crashed following a mid-air collision near Northwood, United Kingdom. All seven aboard the York and all 32 aboard the DC-6 were killed. The SAS Douglas DC-6, “Agnar Viking”, was flying from Stockholm to RAF Northolt with an en route stop at Amsterdam-Schiphol International Airport (AMS), the Netherlands. At the same time, the York transport plane, operated by the RAF 99th Squadron was also heading to RAF Northolt following a flight from Malta. At 14:45 the Northolt tower controller gave the DC-6 crew permission to descend to 2,500 ft. At 14:52 the DC-6 reported “Just passed 2,500 ft; going down.” The controller reminded the pilot that he was only cleared to 2,500 ft and not to descend. At 14:59 the DC-6 crew decided to divert back to Amsterdam due to the weather conditions at Northolt and informed the tower. The DC-6 was cleared to leave the area at 2,500 ft at 15:03 although this was not acknowledged by the DC-6 crew. At 14:38 the York had been instructed to circle Northolt at 5,000 ft and at 14:50 was cleared to descend down to 4,000 ft. At 14:54, three minutes after the DC-6 reported at 2,500 ft, the York was cleared down to 3,000 ft. At 15:03 the two aircraft collided about 6.4 km north of Northolt. The York was above the DC-6, and the DC-6 was climbing. The starboard wing of the DC-6 penetrated the York on the starboard side behind the freight door and detached the York’s tail unit. Both aircraft crashed into some woods, bursting into flames on impact. PROBABLE CAUSE: “The cause of the loss must in all probability be found in the field of human fallibility on the part of those responsible for the control of the aircraft from the ground or the flight of the aircraft in the air.”