| Executive Summary: | The A340 was en-route from Istanbul to New York and the A330 was en-route from London to Ottawa. Both aircraft were assigned to North Atlantic (NAT) Track E with an entry point into Oceanic Airspace of 58°North 10°West and a next reporting point of 59°N 20°W. Both aircraft were cleared by the Scottish Oceanic Area Control Centre to cruise at Mach 0.82 with the A340 at Flight Level (FL) 360 and the A330 1,000 feet above at FL 370. The vertical separation distance of 1000 feet was in accordance with RVSM (Reduced Vertical Separation Minima) used by approved aircraft within NAT MNPS (Minimum Navigation Performance Specification) Airspace. The objective of RVSM is to reduce the vertical separation of aircraft flying between FL 290 and FL 410, inclusive, from the previous 2,000 feet to 1,000 feet, in order to improve fuel efficiency and increase traffic capacity. At the time of the incident each aircraft was using SELCAL (Selective Calling) but on different HF radio frequencies. They were beyond radar coverage but both crews were monitoring the common VHF radio frequency used for air to air messages. Both aircraft had a limiting speed at their respective flight levels of 0.86 Mach.
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