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Airspace Change Proposals Post-Implementation Reviews (PIRs) impacted by COVID 19 - Update October 2021

This page was amended on 04/10/21

A Post-implementation review is conducted at Stage 7 of the Airspace Change process for CAP 1616 and CAP 725 airspace change proposals. The purpose of the PIR is to enable the CAA to consider whether the anticipated impact and benefits of the change have been delivered. To inform this review, which usually takes place 12 months after the change has been implemented, the change sponsor is required to commence the collection of data on the impacts of the change as soon as the change is implemented and to collect a year of data. The data is used to enable a comparison to be made between pre and post implementation operations. A year of data is required to provide data on all operating conditions which change over the seasons. Indicative PIR data requirements are listed in CAP 1616 and include impact on airspace users, those on the ground and any environmental impacts.

Due to the Covid-19 pandemic and its impact on air operations around the globe including in the UK PIR data collection has been suspended, since our first website update in August 2020.

In our February 2021 update to this page we stated that PIR data collection and analysis should commence for any ACP which has been implemented on or after 27 February 2020 on 1 October 2021 for a 12 month data collection period (i.e. until 30 September 2022).

We have reviewed that position. It is our view that the effect of the pandemic on the use of airspace continues to result in a very different use of airspace than could have been contemplated pre- February 2020. In our view any data collected at this time for either CAP725 or CAP1616 ACPs would be unusable in a PIR process as expected and outlined in CAP 1616 (Stage 7 and Annex H) and will inevitably indicate use of airspace different to that which was anticipated. In our view using this data would lead to false results in PIRs.

We have therefore taken the view to delay further the re-commencement of data collection for PIR purposes. We will review this position again in February 2022. We consider if travel restrictions continue to be lifted, we may be in a better position to understand the demand for aviation travel and make an informed decision about PIRs at that time.

Therefore, any data collected between 1 March 2020 and 28 February 2022 cannot be used as part of a PIR data set. This statement applies to all implemented ACPs due to commence a PIR.

Additionally, where PIR data collection was commenced before the onset of the pandemic our policy remains that:

Any PIR data collected by a change sponsor and any analysis by the sponsor which has been completed by 27 February 2020, can be used to as part of a PIR dataset necessary to complete the PIR review in accordance with CAP 1616 or CAP 725 as appropriate.

  1. Any PIR data collected by a change sponsor and any analysis by the sponsor which has been completed by 27 February 2020, can be used to as part of a PIR dataset necessary to complete the PIR review in accordance with CAP 1616 or CAP 725 as appropriate.
  2. Where an ACP has been implemented and more than 9 months PIR data collection has been achieved up to 27 February 2020, the CAA may decide it has sufficient data to conduct the PIR review. Where a change sponsor considers that they have such data, they should contact the CAA Airspace Regulation team to determine if this data is sufficient for the PIR review to take place.

All PIRs of ACPs still following 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 Change sponsors with queries regarding the above should contact the CAA at Airspace.Policy@caa.co.uk.

Post implementation reviews

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.

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

Ongoing progress of PIRs

Completed PIRs

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