North Atlantic Tracks

North Atlantic Tracks, officially titled the North Atlantic Organised Track System (NAT-OTS), is a structured set of transatlantic flight routes that stretch from the northeast of North America to western Europe across the Atlantic Ocean. They ensure aircraft are separated over the ocean, where there is little radar coverage. These heavily traveled routes are used by aircraft traveling between North America and Europe, flying between the altitudes of 29,000 and 41,000 feet inclusive. Entrance and movement along these tracks is controlled by special Oceanic Control Centres air traffic controllers to maintain separation between airplanes. The primary purpose of these routes is to allow Air Traffic Control to effectively separate the aircraft. Because of the volume of NAT traffic, allowing aircraft to choose their own co-ordinates would make the ATC task far more complex. They are aligned in such a way as to minimize any head winds and maximize tail winds impact on the aircraft. This results in much more efficiency by reducing fuel burn and flight time. To make such efficiencies possible, the routes are created twice daily to take account of the shifting of the winds aloft and the principal traffic flow, eastward in North America evening and westward twelve hours later.

The first implementation of an Organised Track System across the North Atlantic was in fact for commercial shipping, dating back to 1898 when the North Atlantic Track Agreement was signed. After World War II, increasing commercial airline traffic across the North Atlantic led to difficulties for ATC in separating aircraft effectively, and so in 1961 the first occasional use of NAT Tracks was made. In 1965, the publication of NAT Tracks became a daily feature, allowing controllers to force traffic onto fixed track structures in order to effectively separate the aircraft by time, altitude, and latitude. In 1966, the two agencies at Shannon and Prestwick merged to become Shanwick, with responsibility out to 30W; according to the official document "From 1st April, 1966, such a communications service between such aircraft and the said air traffic control centres as has before that date been provided by the radio stations at Ballygirreen in Ireland and Birdlip in the United Kingdom will be provided between such aircraft and the said air traffic control centre at Prestwick or such other air traffic control centre in the United Kingdom as may from time to time be nominated".

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