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UK Civil Aviation Regulations

These are published by the CAA on our UK Regulations pages. EU Regulations and EASA Access Guides published by EASA no longer apply in the UK. Our website and publications are being reviewed to update all references. Any references to EU law and EASA Access guides should be disregarded and where applicable the equivalent UK versions referred to instead.

Post implementation reviews provide a rigorous assessment by us, as the independent regulator, of whether the anticipated impacts and benefits, set out in the original airspace change proposal and decision, have been delivered and if not to ascertain why and to determine the most appropriate course of action.

The review can be an iterative process and the nature of each review will be determined by the scale and impact of the airspace change itself. The main stages are shown below.

All post implementation reviews will be conducted in accordance with CAP1616 version 5, the requirements of which have not materially changed.


Other information:

All PIRs of ACPs that followed the CAP725 process will be conducted in accordance with the process requirements of CAP1616. However, when assessing the expected impacts against the actual impacts, we will use the methodology applied at the time of the original decision (either UK Air Navigation Guidance 2014 or 2017). Any sponsors with queries regarding the above should contact the CAA at Airspace.Policy@caa.co.uk.

Post implementation review initiated

1. We determine the scope and objectives of the review after discussion with the organisation that requested the change.

This may include:

• A review of what was to be achieved by the change
• Air traffic control/management requirements (safety, delay, capacity efficiencies)
• Military air traffic control/management requirements (if applicable)
• Environmental conclusions
• Effectiveness of the change
• Other benefits or impacts
• Operational impact (feedback gathered from all affected aviation stakeholders)
• A post implementation safety analysis.

2. We identify and confirm the data required from the organisation that requested the change.
3. We may, during our assessment phase, revise the scope and objectives of the review.
4. We may request further information from the organisation that requested the change at any time prior to publication of the report.

Close Post implementation review initiated

Data collection and analysis by the organisation that requested the change

  1. Organisation gathers data and operational feedback and information from stakeholders.
  2. Organisation submits data to us.
Close Data collection and analysis by the organisation that requested the change

Our assessment

  1. We assess the completeness and adequacy of the data submitted.
  2. Where applicable we independently gather aviation stakeholder feedback.
  3. Where applicable we log and analyse written feedback from people and organisations other than airlines, other aircraft operators, airport operators and air navigation service providers.
  4. We assess the operational and environmental impact of the change against the expected impact.
  5. We consider and determine any appropriate consequential action.
Close Our assessment


  1. The organisation that requested the change can provide comments.
  2. The report is published on our website.
Close Report

Airspace Change Proposals Post-Implementation Reviews (PIRs) impacted by COVID 19

A Post-implementation review is conducted at Stage 7 of the Airspace Change process for CAP 1616 and CAP 725 airspace change proposals. Information on the purpose of a PIR and how one is carried out is summarised below, and set out in detail in CAP 1616.

Due to the Covid-19 pandemic and its impact on air operations around the globe, any data collected between 1 March 2020 and 28 February 2022 cannot be used as part of a PIR data set.

Reminder of deadline to commence data collection period for all delayed and outstanding PIRs: 27 September 2022

As explained in our last update on 17 February 2022, the sponsors of delayed and outstanding PIRs are required to commence data collection for the purpose of PIRs as follows:

Sponsors of ACPs should commence data collection from 27th March 2022. A phased approach to the commencement of data collection may be taken by sponsors to take account of resourcing requirements. Therefore, the collection of data may be initiated at any point between the 27 March 2022 and 27 September 2022. 12 months of data must be collected.

Sponsors should advise CAA Airspace Regulation of the date they commence data collection. This date should also be published on the sponsor’s website to ensure their stakeholders remain informed of progress.

Additionally, where PIR data collection was commenced before the onset of the Covid-19 pandemic, our policy remains as amended that:

  1. Any PIR data collected by a sponsor and any analysis by the sponsor which had been completed by 27 February 2020 can be used to as part of a PIR dataset.
  2. Where an ACP has been implemented and more than 9 months of PIR data collection had been achieved up to 27 February 2020, the CAA may decide it has sufficient data to conduct the PIR. Where a sponsor falls into this category, they should contact the CAA Airspace Regulation team to determine if this data is sufficient for the PIR to take place.
Close Airspace Change Proposals Post-Implementation Reviews (PIRs) impacted by COVID 19