The guiding principle of air traffic control is that safety is paramount. Controllers must therefore keep the aircraft they handle safely separated using internationally-agreed standards. This is achieved by allocating different heights to aircraft or by arranging certain minimum horizontal distances between them. These distances vary according to circumstances, but aircraft flying along the airways under radar surveillance, for example, are kept five nautical miles apart horizontally or at least 1,000 feet vertically.
Within the airspace, a network of corridors has been established. These corridors, or airways, are usually ten miles wide and reach up to a height of 24,000 feet from a base of between 5,000 and 7,000 feet. They mainly link busy areas of airspace known as terminal control areas which are normally above major airports. At a lower level are the control zones which are established around each airport. The area above 24,500 feet is known as upper airspace.
All these areas are designated "controlled airspace" and aircraft fly in them under the supervision of air traffic controllers. Pilots are required to file a flight plan for each journey containing details such as destination, route, timing and height.
Within controlled airspace, pilots must follow controllers' instructions; outside controlled airspace they take full responsibility for their own safety although they can ask for assistance. In fact, military controllers, who work closely with their civilian colleagues to provide a fully integrated service to all users, offer an air traffic service to aircraft in uncontrolled airspace. Military personnel also provide services to aircraft crossing airways and for those flying above 24,500 feet. A priority task for them is aiding aircraft in distress.
Aircraft in the initial or final stages of their journey are managed by controllers at the airport itself. When aircraft join the airways system, responsibility for handling them passes to colleagues working at the appropriate area control centre. A flight through their airspace could pass through several "sectors" of airspace, each managed by a different team of controllers.
Safety
The highest priority for NATS is safety. Our safety objective is to maintain and, where practicable, improve standards to achieve the highest levels of safety performance. To this end the whole structure and culture of the company is focused on safety.
En Route Air Traffic Services
NATS provides en route air traffic management services to aircraft flying in United Kingdom and North Atlantic airspace from three locations: Swanwick in Hampshire, Prestwick in Ayrshire and at Manchester airport. NATS has developed a two-centre strategy that will, in the future, mean en route air traffic management will be provided from Swanwick and at a New Prestwick Centre.
Airport Air Traffic Services
NATS provides air traffic control services at 15 of the UK's major airports: Aberdeen, Belfast International, Birmingham, Bristol, Cardiff, Edinburgh, Farnborough, Glasgow, London Gatwick, London Heathrow, London Stansted, London City, London Luton, Manchester and Southampton.
Infrastructure
NATS is responsible for providing a nationwide network of communications, surveillance and meteorology services and associated ground communications. Effectively this means the radar data for the controllers' screens, the radio frequencies they talk to pilots on and the ground communications between controllers. NATS also provides navigational services to airlines and the general aviation community.
