Sovereign airspace is the part of the atmosphere a state controls, including areas over its land and sea out to 12 miles from its coast, where a State is committed by international treaty (Chicago Convention Article) to provide air navigation services, including air traffic control. This airspace cannot be delegated.
Beyond 12 miles from the coast is considered to be airspace over the high seas. The UK, under international treaty, is also responsible for airspace over the high seas, within areas known as flight information regions, which are managed areas.
The UK’s managed airspace is regulated to ensure its design (routes, procedures, structures, etc) allows those who fly in to do so safely and efficiently.
How UK airspace works
Controlled and uncontrolled airspace
Airspace can be divided into two main categories: controlled and uncontrolled.
Controlled airspace is airspace where an air traffic service is provided by air traffic controllers who can utilise a network of routes in order to safely manage passenger and commercial aircraft transits. The routes and procedures within controlled airspace link the areas of airspace above most major airports. At a lower level, some airports have controlled airspace. Control zones (CTRs) ensure air traffic control can be provided to aircraft using the airport or wishing to transit nearby.
The defined structures of controlled airspace, and routes and procedures contained within them, such as standard instrument departures (SIDs) and standard instrument arrivals (STARs), form part of the overall airspace design. This airspace design is published (‘notified’) in the UK Aeronautical Information Publication (AIP).
Uncontrolled airspace is classified as Class G airspace and is where aircraft can fly freely without having to adhere to specific instructions by air traffic control, unless they request air traffic services when available.
The UK Government has directed (The Air Navigation Directions 2023) the CAA to ensure that the amount of controlled airspace is the minimum required to maintain a high standard of air safety and, subject to overriding national security or defence requirements, that the needs of all airspace users are reflected on an equitable basis. The CAA has a policy to ensure that the amount of controlled airspace is safe and efficient to meet the needs of UK airspace users and to comply with our international obligations.
Categories and classes of airspace
UK airspace uses five classes of airspace to maintain a high standard of safety – A, C, D, E and G. There are different flight rules and requirements for air traffic navigating within these different classes.
Controlled airspace - classes A, C, D and E - is found around major airports and includes the route system that aircraft fly in. Air traffic controllers manage the flight of aircraft in controlled airspace to provide safe and efficient operations.
In uncontrolled airspace - class G - pilots are free to choose their own route while complying with various safety rules that may apply. Class G airspace is primarily used by recreational flyers, the military, emergency helicopters and drones.
Overlaying this airspace design are procedures for air navigation services that form a framework of how to operate and manage aircraft within the airspace. Both the airspace design and the procedures can therefore affect how the airspace functions and impacts aircraft flights.
How UK airspace is managed
There are several organisations involved in managing and administrating airspace for which the UK is responsible. The organisations all have clear roles and responsibilities.
These include the Department for Transport (DfT), the Civil Aviation Authority (CAA), the Ministry of Defence (MoD), NATS, other air navigation service providers, aerodromes and airports.
The Government and The Department for Transport (DfT)
The DfT is the government department who has responsibility for aviation. They set the national aviation policy and standards for safety and security.
Parliament and the Government are responsible for setting the CAA’s statutory objectives (the Directions), outlining our functions and responsibilities, and providing guidance to us. The Secretary of State may, under certain conditions, decide to 'call-in’ a particular airspace change proposal. In this instance the Secretary of State becomes the decision maker for airspace change proposals, instead of the CAA.
The CAA
The CAA is a public corporation, established by Parliament in 1972 as an independent specialist aviation regulator.
We are responsible for deciding whether to approve an airspace change proposal to the notified airspace design for which the UK is responsible.
We make these decisions in accordance with legislation to consider certain factors which include safety, the environment, the needs of users of airspace and government policy, including the airspace modernisation strategy.
The CAA has developed the airspace change process (CAP 1616) to ensure it meets modern standards for regulatory decision-making and is fair, transparent, consistent, and proportionate. The airspace change process is impartial and evidence-based and takes account of the needs and interests of all affected stakeholders.
In addition, the Government sets the policy approach for use of airspace and airspace change proposal decisions taken by the CAA.
The Ministry of Defence (MoD)
Although the Ministry of Defence is part of the Government it can also be a change sponsor in its own right. The CAA also has its own statutory obligations related to national security that involve the Ministry of Defence.
NATS
NATS is the main Air Navigation Service Provider (ANSP) in the UK and provides air traffic control services to most aircraft flying in UK controlled airspace. It is regulated by the CAA. Aircraft operating outside of controlled airspace are responsible for their own navigation, but they can ask NATS or other local ANSPS for assistance.
Airports/Aerodromes
The airport or aerodrome operator has responsibility for ensuring the safety and efficiency of aircraft operating in the vicinity of the airport or aerodrome. The area of responsibility varies according to the size and scale of operations.
The Change Sponsors role
The change sponsor owns the airspace change proposal and is responsible for developing and resourcing it, including considering feedback from relevant stakeholders in accordance with the CAA’s airspace change process.
Anyone can sponsor an airspace change proposal. In some cases, the change sponsor will work in partnership with other organisations (for example aviation/airspace consultancy firms or approved procedure design organisations) when developing their airspace change proposal. However, the change sponsor remains solely responsible for complying with the airspace change process.