CAP 1616 version 5.1 Airspace Change process
Overview of version 5.1 of CAP1616.
On 1 October 2026, an updated CAP 1616 version 6, Airspace Change Process will come into effect. This updated process will apply the government’s updated legislation the Air Navigation Directions 2026 and the Air Navigation Guidance 2026.
All new airspace change proposals submitted after 1 October 2026 will follow CAP 1616 version 6.
Some airspace change proposals are also permitted by the Secretary of State and the CAA to continue to apply the Air Navigation Guidance 2023 and to follow previous versions of CAP 1616. The previous versions of CAP 1616 can still be found on the CAP 1616 page.
Understanding CAP 1616 version 5.1, airspace change process
The CAP 1616 version 5.1, Airspace Change Process is made up of different stages and gateways. The requirements vary depending on the type of airspace change proposal requested. On this page we provide a summary of the change process for:
- Permanent changes
- Temporary changes and airspace trials
- Planned and permanent redistribution of air traffic.
CAP 1616 version 5.1 has seven stages. The CAA monitors the progress of an airspace change proposal against the requirements of the airspace change process at key defined points, called gateways. There are three gateways, at the end of Stage 1, at the end of Stage 2, and during Stage 3.
The CAA holds monthly gateway assessment meetings. At each gateway the change sponsor must submit the required outputs to the CAA for assessment and publish them on the airspace change portal. The CAA will complete a regulatory assessment of the change sponsor’s outputs and relevant supporting evidence to determine whether the airspace change process requirements have been followed.
Passing a gateway does not predetermine the CAA’s regulatory decision on the final airspace change proposal submitted at Stage 4. The gateways are to determine whether the airspace change process has been followed up to that point, and whether to approve progress to the next stage.
The CAP 1616 version 5.1 process for permanent airspace change proposals
The requirements of the airspace change process vary depending on the scale and complexity of the proposal. For Level 1 and Level 2 permanent airspace change proposals following CAP 1616, version 5.1, Airspace Change Process, the full process is set out in CAP 1616f: Guidance on Airspace Change Process for Permanent Airspace Change Proposals.
For Level 3 permanent airspace change proposals following CAP 1616, version 5.1, Airspace Change Process, a proportionate set of minimum requirements applies. These are detailed in CAP 1616h: Guidance on Airspace Change Process for Level 3 and Pre-Scaled Airspace Change Proposals.
The process begins with the change sponsor identifying and explaining the need for an airspace change through a statement of need. This outlines the objectives of the proposal, the issues it seeks to address, and any opportunities it could create.
An assessment meeting is then held to determine whether the airspace change process is the appropriate mechanism for the change. Following this, the CAA and change sponsor will agree a timeline for the proposal.
The change sponsor must then develop a current-day scenario and develop a set of design principles. These principles provide the framework against which design options will be developed and evaluated. These are shared with key stakeholders. The change sponsor must demonstrate what they have heard and how their stakeholders’ feedback has, or has not, informed the content of the current-day scenario and development of the design principles.
Durin Stage 2, the change sponsor develops potential airspace design options and develops the baseline scenarios. The baseline scenarios allow a comparison to be made between the impacts of the design options and the impacts without an airspace change.
The change sponsor engages with relevant stakeholders on the baseline scenarios and the design options. The change sponsor then conducts a design principles evaluation. This evaluates the design options against the design principles that were developed in Stage 1 and may result in some options being discounted.
The change sponsor then carries out an initial options appraisal, where the impacts of the remaining design options are assessed against the baseline scenarios, and further options may be discounted.
Options appraisal is an iterative process that is developed in later stages as the change sponsor refines their proposals. The options appraisal provides clear, comparable evidence on a range of factors, enabling a consistent comparison and assessment of different airspace design options for a given proposal.
Stage 3 focuses on the sponsor gathering feedback on their proposed designs. Effective stakeholder engagement is a vital underpinning of the airspace change process.
The change sponsor develops the initial options appraisal into the full options appraisal, providing a more quantitative assessment of the remaining design options.
The change sponsor then prepares for consultation. This is the key stage of the airspace change process when change sponsors seek feedback to help them understand stakeholders’ views about the impacts of their airspace change proposal. Whether this requires a full public consultation or targeted engagement with relevant stakeholders will depend on the scale and impacts of the airspace change proposal.
Following successful completion of the Stage 3 gateway, which occurs in the middle of stage 3, the change sponsor launches its consultation.
Following the consultation, the change sponsor must review and analyses all consultation responses. Stage 3 ends with the publication of the change sponsor’s consultation response document on the airspace change portal.
In stage 4, the change sponsor makes any final adjustments to their airspace design ahead of submitting the final airspace change proposal to the CAA.
The change sponsor selects a final design option and considers any updates based on feedback from the consultation or engagement. The change sponsor completes the final options appraisal and assess whether additional consultation or engagement is required.
The stage concludes when the final airspace change proposal, together with supporting evidence and documentation, is submitted to the CAA and published on the airspace change [ortal, with any necessary redactions.
Stage 5 is where the CAA reviews and assesses the final airspace change proposal. The CAA may need to request supplementary information or technical corrections and clarifications from change sponsors.
For Level 1 proposals, the CAA may convene a public evidence session and/or publish a draft decision, when it is proportionate to do so.
The CAA will then decide whether to approve the final airspace change proposal. The CAA’s decision may be subject to modifications to, and conditions on, the final airspace change proposal as the CAA considers necessary. These modifications and/or conditions will need to be fulfilled by the change sponsor either before, or after, implementation.
Alternatively, the Secretary of State may ‘call-in’ the proposal and make the decision, and the CAA will instead give the Secretary of State a ‘minded to’ decision. You can find more information about how the Secretary of State call-in works on this page.
Once approved, the change sponsor moves into implementation. The change sponsor must fulfil any conditions or modifications set out in the regulatory decision, finalise and submit aeronautical data to the CAA for validation and update all relevant documentation where needed.
Following implementation, the change sponsor must monitor the impacts of the change and continue to engage with stakeholders, ensuring that feedback is considered regarding the impacts of the airspace change.
Stage 7 is where the post implementation review analyses the impacts of the implemented airspace change to allow the CAA to determine if it has produced the intended outcomes. The post implementation review is not a review of the decision that was made on the final airspace change proposal, and it is not a re-run of the decision-making process.
A post implementation review must be completed for all Level 1 airspace change proposals. It will only be completed for Level 2 and Level 3 airspace change proposal when the CAA determines that it is proportionate to do so.
You can read more about the post implementation review process on our post implementation review pages.
The CAP 1616 version 5.1 process for temporary airspace change proposals
Specific events or operating conditions may sometimes require a temporary change to the notified airspace design.
Under CAP 1616, version 5,1, a temporary change will usually apply for a period no longer than 90 consecutive days, after which the airspace will revert back to its original form. Should a change be required for longer than 90 days, or should we receive a request to repeat a temporary change that has previously been in effect for 90 days, a permanent airspace change proposal will normally be needed.
An airspace trial is defined as changes to airspace design, or air traffic control operational procedures (which if subsequently made permanent would constitute a relevant planned and permanent redistribution of air traffic), of a temporary nature for the purposes of:
- investigating the feasibility of, or validating proposals for, innovative airspace design, technology or air traffic control operational procedures
- assessing its performance and effect
- supporting the development and integration of new airspace user groups into UK airspace.
An airspace trial may result in the establishment of a temporary airspace structure (such as temporary special use airspace). However, the distinction from a temporary airspace change should be noted. An airspace trial is where innovative airspace design, technologies or procedures are being trialled. A temporary airspace change is used to meet a specific event or operating conditions for a short period.
The duration of an airspace trial can vary and is for a fixed period as the CAA considers appropriate, which is normally not more than six months.
The airspace change process for temporary changes to the notified airspace design and airspace trials is summarised below. There are no gateway assessments for temporary or trial airspace change proposals.
The first stage of the temporary and trial airspace change process, the ‘define’ stage, begins with the change sponsor submitting a statement of need. This sets out the objectives of their airspace change proposal and the airspace issues or opportunities that it seeks to address.
An assessment meeting to discuss the statement of need takes place and, subject to the CAA accepting that the airspace change process is the appropriate mechanism to achieve the objectives of the temporary or trial airspace change proposal and address the airspace issues or opportunities, the change sponsor will go on to the remaining stages of the airspace change process.
For temporary and trial airspace change proposals, the requirements for Stage 2 depend on the nature of the airspace change proposal. The size, complexity and duration of the proposal will be taken into consideration when scaling the requirements of this stage and are discussed at the assessment meeting.
The change sponsor must develop at least one design option and conduct impact assessments for the airspace change proposal. There is no requirement for the change sponsor to conduct the full options development process, design principle evaluation or initial options appraisal.
Stage 3 is where the change sponsor gathers information from stakeholders to understand whether the temporary or trial airspace change proposal will be safe and operationally viable. For temporary and trial airspace change proposals, a scaled form of consultation – engagement – is appropriate at Stage 3.
After developing engagement material, the change sponsor launches their engagement activities. The change sponsor’s explanation of the issues raised during engagement, and their response to the identified issues, are included in their final airspace change proposal submission in Stage 4. The effectiveness of the change sponsor's engagement activities is assessed by the CAA during Stage 5.
In Stage 4 the change sponsor considers the need to update the final design option and its impacts in light of information received during engagement. The change sponsor also assesses the need for additional engagement and makes any final adjustments to the airspace design.
Stage 4 ends with the submission of the final airspace change proposal to the CAA, including any supplementary documents, annexes or appendices, along with publication (redacted where appropriate) on the airspace change portal.
Stage 5 is where the CAA reviews and assesses the final airspace change proposal. The CAA may need to request supplementary information or technical corrections and clarifications from change sponsors.
The CAA then decides on whether to approve the final airspace change proposal. The CAA’s decision may be subject to modifications to, and conditions on, the final airspace change proposal as the CAA considers necessary. These modifications and/or conditions will need to be fulfilled by the change sponsor either before, or after, implementation.
Having completed the ‘decide’ stage, the change sponsor moves on to the implement stage. This is where the change sponsor engages with the CAA and UK Aeronautical Information Service to implement the temporary or trial airspace change using the most appropriate method. Once implemented, the change sponsor will monitor the impacts of the airspace change by collating and reviewing feedback from stakeholders.
There is no post implementation review for temporary or trial airspace changes. However, for airspace trials, the change sponsor is required to produce a post-trial report and publish it on the airspace change portal.
As a minimum the change sponsor must report against the aims and objectives of the trial as detailed in the final airspace change proposal, including whether they were successfully achieved and report on any engagement conducted during the trial and the content of any feedback or complaints. The change sponsor must publish the post-trial report on the airspace change portal and provide a copy to the CAA for review.