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, although they may request information or a 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). Overlaying the airspace design are air traffic control operational procedures – written instructions forming a framework within which air traffic controllers make decision as to how to control individual aircraft.
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). Guidance on the regulatory process for changing the notified airspace design and planned and permanent redistribution of air traffic, is available in our document CAP1616 Airspace Change.
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. The more impactful of such operational procedure changes are therefore also subject to a CAA approval process.
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.
Airspace change process
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 CAP1616 Airspace Change process was implemented in January 2018, to ensure that it meets modern standards for regulatory decision-making, and is fair, transparent, consistent and proportionate. The process ensures that when the CAA decides whether or not to approve a proposal to change UK airspace, it does so in an impartial and evidence-based way that takes proper account of the needs and interests of all affected stakeholders.
We initiated a review of the CAP1616 Airspace Change process in 2021, three years after its implementation. An updated version will be implemented on 2 January 2024. The new version, CAP1616 version 5, addresses key feedback themes identified through the review and focuses on providing simplification, clarification and proportionality.
In addition to publishing CAP1616 version 5, we have also published the following associated requirements and guidance, which will be in force from 2 January 2024:
- Planned and Permanent Redistribution of Air Traffic
- Guidance on Airspace Change Process for Permanent Airspace Change Proposals
- Guidance on Airspace Change Process for Level 3 and Pre-Scaled Airspace Change Proposals
- Environmental Assessment Requirements and Guidance for Airspace Change Proposals
- The guidance for temporary and trial airspace change proposals will be published in due course.
For further information on transition arrangements, please see the CAP1616 review webpage.
Summary of the improvements made to the airspace change process
- The revised process and guidance take into consideration feedback and insights from stakeholders affected by airspace change
- The improvements focus on simplification, clarification, and proportionality and will make the airspace change process easier to follow
- The scope of the airspace change process has been clarified, to focus on changes to existing airspace design or changes that could impact the airspace design. Administrative changes (currently level 0) will no longer be within the scope of the process.
- Level definitions have been modified
- References to ‘steps’ have been removed from the process so that the focus is on the seven stages and related activities within these stages.
- To highlight the degree of compliance expected against each requirement, we have used will/must, should or may – the use of each one has been defined.
- Guidance on temporary airspace change proposals and airspace trials has been separated into a standalone publication
- Outside of the process and associated guidance, we have developed submission checklists for change sponsors to use for Stages 1-4, the use of which will be a mandatory requirement.
- There is more emphasis on development of the current-day scenario and detailed guidance on what should be included.
- Mandatory and discretionary design principles have been introduced.
- There is more emphasis on developing realistic and viable design options.
- Clarification has been provided on development of baseline scenarios and detailed guidance on what should be included.
- Engagement requirements have been explained more clearly
- Clarification on how consultation can be scaled, when appropriate
- The responsibility for moderating consultation responses has been transferred to the change sponsor
- The requirement to publish a consultation response document has been brought forward from Stage 4 to Stage 3.
Stages 4, 5, 6 and 7:
- These stages remain largely unchanged, but we have clarified the requirements and our expectations
The airspace change process is designed to align with the Government’s policy on managing airspace. 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.
The legislative framework to airspace change is explained on our website.
The Civil Aviation Authority (Air Navigation) Directions 2023 require the CAA to publish a prioritisation principles document which contains its general approach to determining the order in which it will consider airspace change proposals submitted to it for decision. The principles can be found in CAP2541 Principles for the prioritisation of airspace change proposal.
The CAA anticipates that there will be a significant number of airspace change proposals (with varying levels of complexity) required to support the Airspace Modernisation Strategy, including the Airspace Change Masterplan. Accordingly, the CAA requires flexibility in how it manages airspace change proposals, giving priority to certain proposals in order to support delivery of that strategy and plan. The CAA also needs to continue to be able to prioritise airspace changes which are required for an urgent safety or national security reason, as well as other airspace changes which are designed to achieve certain Government policy objectives.
The CAA recognises that the prioritisation of ACPs envisaged by the Air Navigation Directions may, on occasions, have an impact on sponsors who have airspace change proposals in progress. As a result, the CAA will seek to minimise disruption as far as practicable to impacted sponsors. It is not our intent to conduct a re-prioritisation of all airspace change proposals currently in progress, but only to prioritise when we believe this is required. Where a sponsor is impacted, the CAA will confirm this with a statement on the Airspace Change Portal. The impacted sponsor will need to propose a new timeline which will need to be agreed with the CAA.
Any aeronautical data associated with airspace change bound for the UK Aeronautical Information Publication (AIP) must be fit for purpose and in line with the necessary aeronautical data quality (ADQ) requirements as set out in UK Regulation (EU) No 2017/373 and UK Regulation (EU) No 139/2014 and further described in CAP1054 Aeronautical Information Management.
The CAA Aeronautical Data Template is our preferred data exchange format and provides a vehicle for the data originator to submit and gain regulatory approval of AIP bound data and supporting metadata associated with CAP1616 Airspace Design submissions in a consistent manner which is in line with the ADQ Requirements. The scope of the data involved can be found in Annex A of CAP1054. Please also read the Aeronautical Data Associated with Airspace Design policy statement.
The following documents are relevant to version 4 of the CAP1616 airspace change process. These links will be updated following the implementation of version 5 of the CAP1616 airspace change process on 2 January 2024.
- CAP1616 Airspace Change: Guidance on the regulatory process for changing the notified airspace design and planned and permanent redistribution of air traffic, and on providing airspace information this document explains the CAA's regulatory process for changes to airspace.
- CAP1616a Airspace Change: Environmental requirements technical annex this document forms a technical annex to CAP1616. This technical annex outlines relevant methodologies for use in environmental assessments relating to airspace change.
- From 2 January 2024, the contents of this publication will be published in CAP1616i, Environmental Assessment Requirements and Guidance for Airspace Change Proposals.
- CAP1616d How decisions about the UK's airspace are made information leaflet describing the CAP1616 airspace change process and airspace modernisation.
- From 2 January 2024, this publication will be withdrawn.
- CAP1616b, CAP1616c and CAP1616e are documents showing what has changed in the second, third and fourth editions of CAP1616 respectively.
- From 2 January 2024, these publications will be withdrawn.
- CAP 1616f, Guidance on Airspace Change Process for Permanent Airspace Change Proposals
- Effective 2 January 2024, this publication provides guidance to the aviation industry on the airspace change process requirements for permanent airspace change proposals as set out in CAP 1616, Airspace Change Process.
- CAP1616h, Guidance on Airspace Change Process for Level 3 and Pre-Scaled Airspace Change Proposals
- Effective 2 January 2024, this publication provides guidance to the aviation industry on the airspace change process requirements for permanent Level 3 and pre-scaled airspace change proposals.
- CAP 1616i, Environmental Assessment Requirements and Guidance for Airspace Change Proposals
- Effective 2 January 2024, this publication provides guidance to the aviation industry on providing environmental and habitats regulations assessments for airspace change proposals.
- Statement of Need form this is an online form that sponsors use to submit to the CAA at the start of the airspace change or PPR process
- Airspace Design: Unusual aerial activities published in the UK AIP (CAP1618) this is a list of changes which do not need to follow the airspace change process.
- The content of this document have been incorporated into CAP1616 version 5. From 2 January 2024, CAP1618 will cover Airspace Information: transparency about airspace use and aircraft movements.
- Airspace Design: Guidelines on moderation of consultation responses (CAP1619) these are policy guidelines on the moderation of stakeholder responses relating to airspace change that are published by the CAA.
- From 2 January 2024, CAP1619 will be withdrawn, and the contents will be incorporated in CAP1616f, Guidance on Airspace Change Process for Permanent Airspace Change Proposals.
- Airspace Policy Statements
- Infographic - How airspace works and who is involved