More About the Post Implementation Review Process from the Airport

Letter from Farnborough Airport Limited to the FACC, 1st April 2022

​Dear FACC Members

Ref: Farnborough Airport; Airspace Change Post Implementation Review (PIR)

We have received confirmation from the CAA outlining the requirements of the airport’s Post Implementation Review (PIR) which is due to commence on the 1st April 2022. Whilst it had originally been expected that the CAA would commence Stage 7 of the PIR process in the latter part of 2020, the significant impact of the COVID-19 related crisis reduced the activity levels of Commercial Air Transport and General Aviation (both GA Business Aviation and IFR/VFR Class G users) to a point where any resulting analysis would not have been suitable for the intended purposes of the PIR. Consequently the CAA took the decision to delay UK ACPs which was a view supported by sponsors and GA stakeholders.

The CAA’s airspace change process is a seven-stage mechanism that is set out in detail in CAP 1616. Stage 7 of this process is a PIR that normally begins one year after implementation of the change. The PIR is an assessment of whether the anticipated impacts and benefits in the approved change and published decision are as expected and where there are differences, what steps (if any) the CAA requires to be taken.

Irrespective of whether the CAA decision to approve the change was made under the previous process (set out in CAP 725), all PIRs should normally be in accordance with the process requirements of CAP1616. However, when assessing the expected impacts against the actual impacts, the methodology adopted at the time of the original CAA decision should be used.

Farnborough Airport will now commence a twelve-month data capture process in line with the CAA’s pre-requested data requirements, the results of which will be sent to the CAA in April 2023 for publication on the portal. Thereafter there will be a 28 day window during which any stakeholder may provide feedback directly to the CAA about whether the impacts of the change are those expected, 12 months on. For clarity, the online portal will not accept stakeholder feedback until the complete set of data has been published in April 2023.

The PIR is a requirement of any Airspace Change Process and looks to identify any subsequent requirements to further modify flight procedures, or the airspace structure (as applicable) to ensure compliance with the original CAA decision (Stage 5 of the ACP process).As part of the PIR, Stakeholders will be invited to comment on whether the implementation of the Airspace Change has had the impacts that were anticipated when the decision to agree to the change was made by the CAA.

The PIR is not a review of the decision on the airspace change, and neither is it a re-run of the original decision process. Data and evidence will be gathered from both the Change Sponsor and other Stakeholders, which will be assessed by the CAA.

CAP1678_20180710 TAG Farnborough Airspace Change Decision-FINAL2_Redacted.pdf (

Details of the CAA’s scope and requested data are shown in appendix 1 of this letter. Further information can be found in CAA’s CAP 1616 appendix H.

The PIR can lead to two possible outcomes, the CAA may:

  • Confirm that the implemented design satisfactorily achieves – within acceptable tolerance limits – the objective and terms of the CAA’s approval, and the change is confirmed; or
  • Require modifications to better achieve the objective and terms of the CAA’s approval; once the modifications have been implemented and operated for a period (approximately six months), there are three further possible outcomes:
    • noting that the modifications did not better achieve the objective and terms of the CAA’s approval, the CAA may conclude that the original design was satisfactory, and the original change is confirmed; or
    • noting that the modifications did not better achieve the objective and terms of the CAA’s approval, the CAA may conclude that the original design was not satisfactory, and the original change is not confirmed. In this case, in order to pursue its change, the change sponsor will need to commence a fresh airspace change proposal from Stage 1; or
    • the CAA may conclude that the modifications do better achieve – within acceptable tolerance limits – the objective and terms of the CAA’s approval and so the modified design is confirmed. We will be contacting key stakeholders from the original ACP consultation process in the coming weeks.

In the meantime, if you have any questions regarding the Post Implementation Review process then please contact us at in the first instance.

​Les Freer Airport Operations Director
For and on behalf of Farnborough Airport Ltd


Environment – ACP Updates

The objective of the proposed airspace change was to create a new operating environment which offers all airspace users predictability and consistency of operation.

Creating a known air traffic control (ATC) environment will assist the airport in catering for an increasing number of air transport movements and do so in a way which enhances efficiency and safety for many airspace users.

Farnborough Airport Limited (formally TAG Farnborough Airport) currently operates within Class G (uncontrolled) airspace, which is shared with other airports, gliding sites and general aviation activities. The ACP would improve the approach and departure environment to the benefit of airport traffic and other airspace users.