• What is airspace?

    In its simplest terms, airspace is the portion of the atmosphere controlled by a State above its territory and areas over the sea within which a State is committed by international treaty to provide air navigation services (which includes air traffic control). It is an invisible national asset. For air traffic control purposes, airspace can be divided into two main categories, controlled and uncontrolled. Controlled airspace is where air traffic control needs to have positive control over aircraft flying in that airspace to maintain safe separation between them. Uncontrolled airspace is airspace where aircraft are able to fly freely without being constrained by instructions in routeing or by air traffic control, unless they request such a routeing or control service.

    Controlled airspace contains a network of corridors, or airways. They link the busy areas of airspace above major airports. At a lower level, control zones are established around each airport. These portions are therefore nearer the ground and closer to population centres. The CAA has a policy of keeping the volume of controlled airspace to the minimum necessary to meet the needs of UK airspace users and to comply with its international obligations.

    The defined blocks of controlled airspace, and flight procedures and routes within them such as standard departure and arrival routes, are together part of the overall airspace design. This airspace design is published in the UK Aeronautical Information Publication (AIP).

    Changes to airspace

    Changes to the design of UK airspace are proposed by an airspace change sponsor, usually an airport or a provider of air navigation services (including air traffic control). The CAA requires the change sponsor of any permanent change to the published airspace design to follow our airspace change process.

    Airspace change proposals vary greatly in terms of size, scale of impact and complexity. Some may have little noticeable operational or environmental impact. Others may require a complex restructuring of airspace with consequences both for airspace users and the environment, including people on the ground impacted by noise. Because controlled airspace carries with it requirements that affect the aircraft and pilots that fly in it, an airspace change can impact airspace users in different ways. In addition, a revision to air traffic control procedures may not involve a change to the design of UK airspace, but it may still have consequences for other airspace users, the environment and people on the ground.

    Subject to operational constraints (including safety), the design of airspace, and the airspace change process, do not specify, or limit future increases in, the volume of air traffic using a piece of airspace at any given point in time. The volume of air traffic using an airport may however be addressed by land-use planning conditions, where relevant.

    The number and scale of airspace change proposals which the CAA receives each year varies considerably. Some approaches by sponsors do not go beyond initial outline conversations and never progress to a proposal. Some proposals can last several years between the first conversation and the final decision.

    The global standard for navigation performance has now shifted from ground-based navigation aids, such as those we have had in the UK for the last 40 years, to navigation performance based on satellite systems and improved aircraft equipment (‘performance-based navigation’). We anticipate that the number of airspace change proposals will increase as a result of changes to European law; a desire by the International Civil Aviation Organization (ICAO) to move to performance-based navigation; and the goals and objectives of the UK’s Airspace Modernisation Strategy. The AMS replaces the Future Airspace Strategy and sets out the ways, means and ends of modernising airspace through 15 initiatives that will modernise the design, technology and operations of airspace, initially focusing on the period until the end of 2024. The new strategy is in response to the Department for Transport tasking the Civil Aviation Authority with preparing and maintaining a co-ordinated strategy and plan for the use of UK airspace up to 2040, including modernisation.

  • In 2015, we started reviewing our process and after nearly three years of detailed work and two public consultations, on 13 December 2017 we launched our new process. This process is effective from January 2018. Detailed guidance about the airspace change process and how to follow it is available in our document - Airspace Design: guidance on the regulatory process for changing airspace design including community engagement requirements (CAP1616). This document also includes guidance on the information the aviation industry should publish to help communities understand noise changes. A second edition of this document is effective from 1 December 2018 which, apart from some changes reflecting new Government directions to the CAA, mainly concerning the 'call-in' process, comprises of editorial changes only. These are primarily clarifications, corrections and updated links.

    Our new process is designed to be transparent, comprehensible and proportionate. The detailed requirements of the process and the date it will come into effect are aligned with the outcome of the Government's 2017 consultation on airspace and noise policy. Read about the Government's policy. Airspace change options are assessed using WebTAG, a series of guides and spreadsheet tools. The Department for Transport have published guidance explaining what WebTAG is and how it can be used to assess noise impacts.

    Decisions being developed under the new CAP 1616 process and those continuing under the old CAP 725 process can be found on their respective pages.

    The following documents set out how the process will work:

    On 21 May 2019 it was announced that Mark Swan, the CAA's Group Director of Safety and Airspace, will leave the CAA later in 2019 to lead the newly established Airspace Change Organising Group (ACOG).  At the request of the Secretary of State for Transport and the CAA,  ACOG has been established by NATS En-route plc (NERL) to create a single co-ordinated implementation plan for airspace change, initially over the South-East of England.

    Proposals to change airspace design and (shortly) some ATC operational procedures (“PPRs”) decisions are made by the CAA.  In practice, CAA employees are authorised by the CAA Board to make decisions as published in CAP 1616.  Level 1 airspace design change decisions can be made either by the CAA's Group Director of Safety and Airspace or the Head Airspace, Air Traffic Management and Aerodromes, John Round.  Mark Swan will no longer participate in the decision-making process for these decisions which will solely be taken by Jon Round, the Head of Airspace, Air Traffic Management and Aerodromes on behalf of the CAA, following the process set out in CAP 1616.  Once Mark Swan's replacement as Group Director of Safety and Airspace has taken up their position, decisions will again be taken either by Group Director of Safety and Airspace or Head Airspace, Air Traffic Management and Aerodromes.  



    On 31 March 2017 we published revised guidance material on the new process for consultation. This will replace our old process document, CAP 725. View our consultation and responses we received (consultation now closed). Our detailed analysis of all of the responses and recommendations we received is available in our report Outcome of the CAA consultation on draft airspace design guidance (CAP 1615).

    The consultation documentation comprised the draft guidance document itself, a draft environmental technical annex to the guidance, a separate document about a new category of airspace change (known as 'Tier 2') which the Government discussed in its consultation, and a pdf version of the CAA's consultation document and questions.

    Our 2017 consultation on the guidance material followed a consultation we held in 2016 on the principles of the new process and an independent review conducted by consultants Helios in 2015.

    See the Related Information below for older information about why we decided to change the process.


    Information about arrangements for transitioning to the new process is available on the transitioning process page on our website


    We have produced a number of policy statements which include technical guidance and information on the process to be followed for certain types of airspace change. The technical information remains valid and should continue to be followed. However, following the publication of the new airspace change process, some process information (that which relates solely to the airspace change process and how it should be followed) in these policy statements is no longer valid and should be disregarded. Please contact the CAA for further information. The guidance on our airspace change process and how it applies to any request for a change to airspace design is now all located in one place: in CAP 1616. In due course we will complete a full review of these policy statements and update them to reflect the new process.