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 30°W longitude; 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".
In 1965, NAT Tracks became a daily routine for controllers, allowing them to direct traffic onto fixed track structures to separate aircraft by time, altitude, and latitude. In 1966, the Shannon and Prestwick air traffic control agencies merged into Shanwick, with responsibility extending to 30°W longitude.  A new communication service was established in April 1966, replacing previous services provided by radio stations in Ireland and the UK.