Oxford Aviation Services Limited & Ors v Civil Aviation Authority & Anor

The Claimants are the operators of private airports at Oxford, Farnborough and Biggin Hill. They seek permission to bring this claim for judicial review of what they contend to be the ongoing failure by the Defendant, the Civil Aviation Authority [“the CAA”], to withdraw or suspend its notification of RAF Northolt [“RAFN”] for use by civil aircraft, or to impose conditions on the use of RAFN for civil flight operations. The Claimants seek to challenge the CAA’s written response provided under cover of a letter from the CAA’s Chief Executive dated 19 July 2024 [“the Decision”] to the concerns raised by the Claimants on 10 January 2024, in relation to the safe operation of RAFN for civil aircraft operations.

The Claimants’ airports service private business jets of the kind which also use RAFN. They are aggrieved by what they consider to be the unfair disparity between the CAA’s regulation of private airports such as they operate and the CAA’s regulation of civil aviation at RAFN.

The Claimants seek to rely on the following grounds of challenge in support of their claim for judicial review –

The claim is contested by both the CAA and the Interested Parties, the Secretaries of State for Defence and for Transport.

On 24 March 2025, Choudhury J ordered a rolled-up hearing of the claim. He gave permission to the Claimants to proceed on the basis of an amended statement of facts and grounds filed on 31 January 2025 [“the ASFG”].

The Claimants have filed witness statements by Mr William Curtis, Managing Director of the First Claimant; by Mr Robert Walters, Commercial Director of the Second Claimant; and by Mr Simon Geere, the Chief Executive Officer of the Third Claimant. The Claimants have permission to rely on the expert report dated 6 June 2025 of Mr Alexander Hartland. Mr Hartland is an aviation consultant and a corporate jet pilot. Mr Hartland has also submitted a further statement in response to evidence filed on behalf of the CAA. For the Defendant, evidence in the form of three witness statements has been filed by the CAA’s Principal Inspector (Aerodromes), Mr Neil Gray; and three witness statements by the CAA’s Airspace Regulator (Instrumental Flight Procedures), Mr Terence Ngai. For the First Interested Party, witness statements have been filed by the Aerodrome Operator at RAFN, Wing Commander Max Bond; and by Mr Alan Muir, Technical Director of Pell Frischmann Consultants Limited.

At the hearing, Mr Charles Béar KC and Mr Patrick Halliday represented the Claimants, Ms Monica Carss-Frisk KC and Ms Jane Collier represented the CAA and Ms Gemma White KC and Mr Max Mills represented the Secretaries of State. I am very grateful to them all for their helpful written and oral submissions.

By virtue of the provisions of section 1 of the Civil Aviation act 1982 [“the 1982 Act”] the Secretary of State for Transport is charged with the general duty of organising, carrying out and encouraging measures for the development of civil aviation, for the promotion of safety in the use of civil aircraft and for safeguarding the health of persons on board aircraft. The Secretary of State carries out those duties through the CAA, which has been constituted as a body corporate in accordance with section 2 of the 1982 Act.

Section 3 of the 1982 Act states the CAA's functions, which include –

Section 4 of the 1982 Act imposes a duty on the CAA to perform its functions in the manner in which it considers is best calculated –

Under section 2 of the Transport Act 2000, the CAA must exercise its functions so as to maintain a high standard of safety in the provision of air traffic services.

Section 60 of the 1982 Act provides for an Air Navigation Order to be made by Order in Council. An Air Navigation Order may contain provisions for carrying out the Chicago Convention on International Civil Aviation ["the Chicago Convention"]and any Annex to the Chicago Convention relating to international standards and recommended practices; or provisions generally for regulating air navigation: section 60(2). Amongst among matters, section 60(3) states that an Air Navigation Order may contain provision –

The relevant Order currently in force is Air Navigation Order 2016 (SI 2016/765) ["the ANO"]. Part 8 of the ANO deals with aerodromes.

Articles 207, 208 and 211 of the ANO provide –

Schedule 1 to the ANO defines a “Government aerodrome” as any aerodrome in the United Kingdom which is “in the occupation of any Government Department or visiting force”.

The Chicago Convention was signed on 7 December 1944 by 52 Contracting States, including the United Kingdom, and entered into force on 4 April 1947. The Chicago Convention established the International Civil Aviation Organization [“ICAO"] as a specialised agency of the United Nations. The UK is a member of ICAO's Governing Council.

Article 37 of the Chicago Convention provides that the ICAO is to adopt, and amend from time to time, international standards and recommended practices for international civil aviation. “ICAO standards” and “ICAO recommended practices” are set out in 19 detailed Annexes to the Chicago Convention, collectively referred to as "SARPs". ICAO Standards are specifications the uniform application of which is recognised as necessary for the safety or regularity of international air navigation. ICAO Recommended Practices are specifications the uniform application of which is recognised as desirable for the safety or regularity of international air navigation.

Although article 3 of the Chicago Convention expressly excludes its application to state aircraft including those involved in military service, the Convention does not distinguish between military and civil airports. Civil use of military airports such as RAFN is therefore within the scope of the Chicago Convention. Annex 14 to the Chicago Convention sets out in very great detail SARPS for the design, operation and maintenance of aerodromes. Paragraph 1.2.2 of Annex 14 states that it applies to all aerodromes open to public use.

Article 38 of the Chicago Convention provides that in cases where a Contracting State finds it impracticable to comply in all respects with an ICAO standard or deems it necessary to adopt regulations or practices which differ in any particular respect from an ICAO standard, it must notify ICAO of the “difference”. This applies only to a departure from an ICAO standard, not an ICAO recommended practice. Nevertheless, Annex 14 invites Contracting States voluntarily to notify a difference from a recommended practice as well as complying with the compulsory requirement imposed by article 38 to notify a difference from a standard.

In 2002 the Second Interested Party filed a difference with the ICAO which provided that there was no requirement for Annex 14 to apply at all to Government aerodromes. As a matter, therefore, of international treaty obligations under the Chicago Convention, Annex 14 does not apply to RAFN.

Article 212 of the ANO enacts arrangements for the licensing of aerodromes by the CAA. The CAA must grant a licence for any aerodrome in the United Kingdom if it is satisfied that the applicant is competent, having regard to its previous conduct and experience; and that its equipment, organisation, staffing, maintenance and other arrangements to secure that the aerodrome and the airspace within which its visual traffic pattern is normally contained, are safe for use by aircraft. The CAA must also be satisfied that the aerodrome is safe for use by aircraft, having regard in particular to the physical characteristics of the aerodrome and of its surroundings; that an effective safety management system is in place; and that the manual for the aerodrome is adequate.

In order to give guidance on the discharge of its licensing function pursuant to article 212 of the ANO, the CAA has published Civil Aviation Publication 168 “Licensing of Aerodromes” [“CAP 168”]. The relevant edition of CAP 168 for the purposes of the present claim is the 12th edition (January 2022). In the introduction to CAP 168 the CAA stated its purpose as being –

Chapter 4 of CAP 168 states the CAA’s regulatory guidance on the assessment and treatment of obstacles. Paragraph 4.1 states –

Paragraph 4.2 summarises the method of assessing the significance of objects within or close to the boundary of a licensed aerodrome, with particular reference to the role of “obstacle limitation surfaces”[“OLS”] -

Paragraph 4.3 gives examples of “safety measures” which may be considered by the CAA in cases where OLS are infringed -

OLS include the “take-off climb surface” [“TOCS”] and the “approach surface”. These concepts are described and given specifications in paragraphs 4.8 to 4.22 of CAP 168. A TOCS is an inclined plane located beyond the end of the take-off run available or the end of the clear way where one is provided. A TOCS is established for each runway direction intended to be used for take off. Figure 4.11 provides a diagram of OLS for an instrument runway where the main runway is 1800 metres on more in length.

Guidance on the restriction and removal of obstacles is given from paragraph 4.50 onwards of CAP168. Referring to concepts identified on Figure 4.11, paragraph 4.52 states –

The ICAO has published Procedures for Air Navigation Services – Aircraft Operations, known as “PANS-OPS” (ICAO Document 8168. PANS-OPS gives detailed guidance on the design of visual and instrument procedures for approach to and departure from aerodromes. Mr Ngai describes PANS-OPS as supporting guidance from ICAO relating to the design and construction of Instrument Flight Panels [“IFPs”] which would be presumed to comply with the PANS-OPS criteria. Their status within the Chicago Convention is explained in the foreword to PANS –

The particular guidance which gives rise to concern in the present claim is to be found in PANS-OPS Volume 2. The foreword to that volume states –

PANS-OPS Volume 2 Chapter 5 “Final Approach Segment” includes guidance on obstacle clearance altitudes and heights which forms the subject matter of ground (1A) of this claim.

RAFN is located in the built-up area of north-west London. It is abutted by the A40 immediately to the west and West End Road to the east. RAFN is occupied and operated by the First Interested Party. It is, therefore, a Government aerodrome within the definition given by article 255 of the ANO.

RAFN has one operational runway. When used in a westerly direction, the runway is known as Runway 25. When used in an easterly direction, it is known as Runway 07. The paved surface of the runway is 1,687 metres in length. Not all of the paved runway is available for the landing and take-off of aircraft. The length of the available runway is declared in the UK MilitaryAeronautical Information Publication [“MIL AIP”]. Part AD2 of MIL AIP provides detailed aeronautical information in relation to individual aerodromes, that for RAFN being published under the location indicator and name “EGWU – Northolt”. That information includes “Declared Distances” specifying the available operational runway at RAFN.

RAFN has been notified without conditions by the CAA pursuant to article 211 of the ANO (or its statutory predecessors) since 2002.

In R (Oxford Aviation Services and Biggin Hill Airport Ltd) v Secretaries of State for Defence and for Transport and the Civil Aviation Authority [2015] EWHC 24 (Admin) [“the 2015 Judgment”], the principal issue before the court was whether the Government’s arrangements for overseeing and regulating the use of RAFN by civil aircraft were lawful, particularly in respect of safety. At [11] Popplewell J said that the main complaints raised by the claimants in that case were –

As to the first complaint, at [38] in the 2015 Judgment Popplewell J said that the power to notify RAFN as available for civil aircraft use rests with the CAA, with the concurrence of the Second Interested Party, now under article 211 of the ANO. Article 211 includes the power to impose such conditions as the CAA thinks fit, which can be formulated by reference to safety conditions. At [43], Popplewell J said that the CAA was not able to fulfil its statutory responsibilities pursuant to article 211 of the ANO by delegating to the MOD and MAA the task of assessing the safety of RAFN for use by civil aircraft –

At [46] in the 2015 Judgment, Popplewell J rejected the claimants’ second main complaint –

In his first witness statement, Mr Gray confirms that licensed aerodromes are required tocomply with the requirements set out in CAP 168, which is the UK policy document that sets out the Annex 14 SARPs applicable to civil aerodromes. Mr Gray says that whilst the civil safety standards upon which civil aerodromes are licensed are notdirectly applicable to Government aerodromes, those safety standards are used as a basis formaking an informed decision regarding the design and operation of a Government aerodrome and its suitability for civil operations to take place. He states the CAA’s approach as follows –

Mr Gray explains that whereas safety standards for licensed civil aerodromes are set out in civil aviation publications such as CAP 168, safety standards for Government aerodromes are contained in a series of Regulatory Articles [“RAs”] produced by the MAA as regulator. Where the standards in RAs differ from ICAO Annex 14 SARPs, the MAA haspublished those differences in Part 1.7 of MIL AIP.

Differences from ICAO Annex 14 SARPs specific to an individual Government aerodrome are published in the individual Defence Aerodrome Manual for that aerodrome [“DAM”]. The DAM describes the aerodrome, including the management, physical characteristics, services available and operating procedures at that aerodrome. The DAM is written to inform and direct military and civilian aircrew using the aerodrome; and to provide orders for personnel operating on the aerodrome or providing aerodrome services. The DAM is required to conform with the guidance provided by the MAA in RA1026 and be consistent with CAP 168 annual requirements.

Annex D of a Government aerodrome’s DAM contains the Aerodrome Operating Hazard Log [“AOHL”]. Eachhazard has an identification number and a specific entry describing the nature of the hazard, theRA contravened, its impact, mitigating activity and a record of actions taken in relationto the hazard. The AOHL is subject to quarterly review by the aerodrome operator for RAFN. The AOHL issued in March 2024 logs and explains some 36 operating hazards at RAFN. They include –

Annex F of the RAFN DAM provides details in respect of all Aerodrome Alternative Means of Compliance (AAMC), Waivers and Exemptions. Those listed are non-compliant approach lighting, non-compliant taxiway lighting, runway strip obstructions, runway end safety area, OLS and buildings infringing the OLS. In respect of runway strip obstructions, OLS and buildings infringing the OLS, the given details include –

Civil aircraft operators using RAFN, therefore, have access to publicly available information about operating conditions at the aerodrome through access to published data in the DAM, in the MIL AIP and in the AOHL.Having stated that the CAA may not treat the decision whether RAFN meets safety criteria and standards for use by civil aircraft as one for the MOD/MAA rather than itself, at [44] and [45] in the 2015 Judgment Popplewell J said –

In paragraphs 5 to 17 of his first witness statement, Mr Gray describes the safety assurance framework which the CAA applies in relation to Government aerodromes notified for civil aviation pursuant to article 211 of the ANO –

Mr Gray says that these arrangements, which are underpinned by the Agreement, enable the CAA to ensure that it discharges its obligations for safety assuranceat Government aerodromes through liaison with his counterparts in theOperations Assurance Group of the MAA. He says that hitherto the GACG has met on a quarterly basis to coordinate safety activity for civilianoperations at Government aerodromes. Following the latest review of the MoU, it hasbeen agreed to change the frequency of GACG meetings from quarterly to biannually, with furtherad hoc meetings where considered to be necessary. The GACG has also decided to replace the complexity matrixin favour of focusing on all Government aerodromes that have an entry in the MIL AIP. Thedecision to include a Government aerodrome in the safety assurance process will inthe future be based simply on the use of the aerodrome by civil operators for commercialpurposes.

The CAA undertook a safety assurance visit to RAFN in June 2024. The CAA had previously undertaken such visits in 2018 and 2022.

Mr Gray points out that due to their geographical situation, local operating conditions or other historic factors, not all UK aerodromes, whether civil or military, are or can be fully compliant with the specifications set out in their respective regulatory frameworks. For this reason, in the case of civil aerodromes, the CAA has flexibility to deal with the different situations encountered. The introduction to CAP 168 takes a holistic approach to regulation in the light of the specific operating conditions of each licensed airport –

Deviations from regulatory specifications at specific aerodromes are recorded as‘variations’ and will be reviewed both by the aerodrome licence holder, through itssafety management system and by the CAA periodically, through itsaerodrome oversight audits and inspections.

Mr Gray says that many aerodromes(including Biggin Hill, Oxford and Farnborough) have in their vicinity features in thenatural and built environment that penetrate the OLS. He refers to chapter 4 of CAP 168 for guidance onhow such obstacles should be assessed and treated at licensed aerodromes.

Mr Gray states that the processes used by the CAA and the MAA to oversee the safety and compliance of aerodromes that fall within their jurisdiction have some similar features. For example, the CAA holds the civil aerodrome licence holder to account for ensuring the safe operation of the aerodrome, whilst the MAA holds the Head of Establishment at a military aerodrome to account for the same purpose. The CAA Inspectors will visit each civil aerodrome periodically as part of their audit and inspection programme. They will assess compliance with regulatory requirements, audit the management of safety and assess the competence of those responsible for safety. The MAA conducts its safety oversight of Government Aerodromes in accordance with MAA01: Military Aviation Authority Regulatory Principles.

In his witness statement Commander Bond states that his principal role as Aerodrome Operator at RAFN is to support the Head of Establishment and providing a safe operating environment for aircraft. His responsibilities include establishing and maintaining formal mechanisms for the management and assurance of all aerodrome activities, operating procedures, standards, air safety and regulatory compliance.

Commander Bond states that the risks associated with aerodrome operations are managed to ensure that they are as low as reasonably practicable [“ALARP”], through a combination of compliance with MAA RAs, personal accountability and external audit. Change management, including new procedures and infrastructure developments, requires hazard review, sentencing meetings and the production of safety assessments. These are scrutinised by the Aerodrome Operator before approval by the Head of Establishment at RAFN. Compliance with MAA regulations is maintained through a series of mandated internal reviews and external inspections.

Commander Bond explains that the process for preserving a safe operating environment with regard to potential hazards within RAFN’s obstacle environment runs on an annual cycle of activity, comprising of five elements –

The primary mechanism for the monitoring ofRAFN’s aerodrome obstacle environment is an annual, CAP 1732 compliant survey. Since 2020 that annual survey has been conducted by Pell Frischmann. Principal purposes of the annual survey include the identificationand measurement of any new obstacles that have been erected between survey cycles, such as cranes or other construction obstacles erected with the permission of RAFN’s Air Traffic Control; and to check the height of existing obstacles which may havegrown in the intervening period, such as trees. There is a separate, more dynamicprocess for the daily management of such potential hazards. Obstacles may also be reported directly to the Aerodrome Operator by pilots using theairfield should they determine a hazard. Since RAF aircraft and pilots operate from RAFN on a daily basis, a hazardous obstacle would likely be reported by them in the firstinstance. Commander Bond says that there have been no documented instances of such pilot-led reporting at RAFN.

Data gathered through the annual aerodrome surveyis provided to RAFN’s Air Traffic Control and to the Defence Infrastructure Organisation’s [“DIO”] appointed contractor to produce the Instrument Flight Procedure AnnualMaintenance Report [“IFPR”]. The gathered survey data is also published by No 1 Aeronautical Information Documents Unit[“No 1 AIDU”] for analysis by other aerodrome users, in the form of the Measured Height Survey.

RAFN may take immediate action in response to annual survey data. Commander Bond gives the example of reducing the height of a tree which is considered to present an unacceptable obstruction. However, RAFN’s normal practice following receipt of the annual survey data is to await the detailed analysiscompleted in the IFPR by the DIO’s expert contractor, Osprey Consulting Services Limited [“Osprey”]. In the IFPR, Osprey will scrutinise the procedures used by pilots to arrive and depart from the aerodrome. Osprey will provide a seriesof findings and corrective actions in the IFPR, allocating each finding a priority level. Commander Bond produced an extract from Osprey’s RAFN IFPR 2024 which reported Tree 1866 as the one obstacle which penetrated both the VSS and the OCS.

Commander Bond says that issues identified in the IFPR typically require action by either No 1 AIDU or, if physical maintenance activity is required, by the DIO and RAFN. No 1 AIDU’s remit is to maintain information provided in RAF Northolt’s Instrument Approach Procedures, including information about an obstacle in the Greater London area that affects the flight altitude of a published approach. Issues identified in the aerodrome’s immediate surroundings will be likely torequire engagement with external stakeholders, such as the local authority or privatelandowners. The DIO leads this response through its regional engagement teams.Some identified hazards are unable to be mitigated inpractice. These include historic buildings whose existence pre-dates the modern regulatory system. Such hazards are notified to airfield users through the AOHL annexed to the RAFN DAM. TheAOHL is reviewed on a quarterly basis.

Both the AOHL and the DAM are publicly available on RAFN’s commercial aviation website. More urgent safety issues are notified to airfield usersvia the Notice to Airmen [“NOTAM”] system. The CAA’s Safety NoticeSN–2015/007 Version 2 issued on 7 March 2024 [“the updated Safety Notice”] states –

On 10 January 2024 the Claimants wrote to the CAA, stating that they were “more concerned than ever about civil aviation safety at RAF Northolt”. The Claimants asked the CAA –

The Claimants’ letter then set out the supporting information and detailed contentions upon which they relied in making that request. In relation to runway declared distances and the obstacle environment at RAFN, the Claimants submitted and relied heavily on four technical reports –

The Claimants’ letter summarised the matters identified in the four reports –

The Claimants stated –

On 30 January 2024 Mr Gray convened an internal meeting at the CAA to carry out an initial review of the contents of the Claimants’ letter and decide how to proceed. It was agreed that an initial letter in response should come from the Chief Executive of the CAA. An extraordinary meeting of the GACG should be convened to discuss the contents of the Claimants’ letter with the MAA. Safety Notice (SN 2015/007) “Use of Government/Military Aerodromes by Civil Aircraft Operators” (November 2015) should be reviewed, updated and reissued. The latest survey data and IFP designs should be obtained from RAFN. It was agreed that the CAA should collaborate with the MAA to decide whether the concerns raised in the Claimants’ letter were valid; and to make arrangements to obtain evidence to support a response to each of the concerns raised by the Claimants.

It was agreed that in order to give full consideration of those concerns it was appropriate to divide them into the following categories –

On 5 February 2024, the CAA’s Chief Executive wrote to the Claimants informing them that he had now asked the CAA team, through the GACG, to engage with the MAA to investigate the concerns raised in the Claimants’ letter. He expected to respond substantively by the end of March 2024. On 7 February 2024 the Claimants replied inviting the CAA to curtail use of RAFN for civil aviation operations pending the outcome of the CAA’s investigation and safety could be assured.

On 8 February 2024, the GACG met to consider the Claimants’ concerns. The GACG identified additional information needed to support the investigation. The need for immediate action to be taken in the interests of flight safety at RAFN was considered. CAA experts, including Mr Ngai, were asked to carry out a desktop investigation of the issues raised by the Claimants on the basis of the six categories into which they had been divided. On 7 March 2024 the updated Safety Notice was published, with the addition of sources of information about Government aerodromes which are available to civil operators, i.e. the DAM, AOHL and AIP; together with a statement encouraging civil operators using Government aerodromes to participate in operational safety forums at aerodromes.

On 25 March 2024 the CAA’s Chief Executive wrote to the Claimants informing them that a full investigation of the points which they had raised would require more time to complete. He explained the division of the concerns raised into the six categories agreed at the internal meeting held on 30 January 2024. He said that no safety issue had yet been identified at RAFN which required the immediate curtailment of use of the aerodrome for civil aviation. On 18 April 2024 the Claimants responded expressing confusion as to how the CAA had arrived at that view and concern about the time now being taken to carry out the investigation of their concerns. On 11 June 2024 the Claimants wrote a chasing letter seeking a substantial response to their safety concerns about civil aviation at RAFN with 14 days.

In June 2024. a team of CAA Inspectors carriedout a scheduled assurance visit to RAFN which resulted in an oversightreport containing a number of observations. The CAA’s desktop investigation into the concerns raised by the Claimants in their letter of 10 January 2024 resulted in the CAA issuing a further oversight report on 15 July 2024 [“Oversight Report 2”]. By way of overview, Oversight Report 2 stated –

Oversight Report 2 contained 23 observations relating to the Claimants’ concerns, each of which recommended corrective action. In accordance with the MoU, the CAA issued the report to the MAA for onward transmission to the Head of Establishment at RAFN. Following investigation of the concerns raised by the Claimants, the CAA did not conclude that they justified denotification of RAFN, the imposition of conditions under article 211 of the ANO or any other safety critical remedial action.

On 19 July 2024 the CAA’s Chief Executive wrote to the Claimants to inform them that the CAA had now completed its investigations into their concerns. He enclosed the Decision – a document headed “Response to London Biggin Hill, Farnborough and London Oxford Airports letter dated 10 January 2024”.

On 24 July 2024, the Claimants wrote to express their dissatisfaction with the Decision. On 5 September 2024, the Claimants’ solicitors sent a letter under the pre-action protocol to the CAA. On 20 September 2024 the CAA responded. The claim was issued on 21 October 2024.

Both Mr Gray and Commander Bond explain the action taken at RAFN to respond to the CAA’s observations in Oversight Report 2. RAFN have created a UAT in which they record the observation, identify the corrective actions required, assign an action owner, outline the actions taken, record any notes, identify the target response date, and indicate whether the observation is open or closed. CAA monitors the target response date and the UAT. Progress is monitored both at meetings of the GACG and by direct inquiry of the MAA.

Mr Gray refers to eight observations which remain relevant to the present claim. Two of those observations have been closed –

The following outstanding observations at the time of Mr Gray’s first witness statement had been given a revised target date for compliance of 31 May 2025 -

In relation to RAFN’s Tree Management Plan (observation ADR.6231), Oversight Report 2 had referred to the tree identified in the aerodrome survey and by Osprey in 2024 as obstacle 1866 which penetrated the VSS-OCS. This tree had now been reduced in height. Mr Ngai had assessed the position and confirmed that it no longer penetrated the VSS-OCS.

The CAA submitted an extract from the most recently updated version of the UAT at the hearing of this claim. In his third witness statement of 26 September 2025, Mr Gray set out the then current status of the observations. I was told that observations 5628, 5620 and 5631 above had since been closed following a meeting with the MAA. The remaining three observations relating to aeronautical studies and the review of PANS-OPS compliance information remained open.

By way of introduction, the CAA referred to the Claimants’ concerns raised in their letter of 10 January 2026, including the request that the CAA assess the runway declared distances and obstacle environment at RAFN. The CAA stated that –

Referring to the 2015 Judgment, the CAA confirmed that it bore statutory responsibility for safety in relation to the use of RAFN by civil aircraft. Paragraphs 9 to 12 of the Decision set out the safety assurance framework explained by Mr Gray in his first witness statement, which I have summarised earlier in this judgment. Paragraph 13 stated that the CAA had made observations to the MAA and RAFN on matters arising from its review of the Claimant’s concerns. Reference was made to Oversight Report 2 and to the response from the Station Commander at RAFN stating that a plan was to be developed to address the observations raised in that oversight report. The CAA confirmed that it did not consider denotification to be appropriate because no regulatory issues affecting flight procedures of sufficient impact had been identified during the course of the review. The CAA recorded the issue of the updated Safety Notice on 7 March 2024.

Paragraphs 19 to 76 of the Decision set out the CAA’s findings and conclusions in respect of the particular concerns raised by the Claimants’ in their letter of 10 January 2026, considered under the six grouped topics agreed at the internal meeting on 30 January 2024 and communicated to the Claimants on 25 March 2024.

On the topic of the CAA’s approach to regulating operational safety of civil aviation at RAFN as a government aerodrome, reference was made to the approach approved by Popplewell J in the 2015 Judgment –

Reference was made to [46] of the 2015 Judgment, which I have quoted at paragraph 38 above. In paragraph 33 of the Decision, the CAA stated –

The CAA also referred to the holistic approach to assessment stated in the introduction to CAP 168. Although the CAA may impose conditions on a notification under article 211 of the ANO, it was stated that the CAA has yet to use that regulatory approach. Its most commonly used approach was to notify the MAA of any issues arising following site inspection or review and to monitor corrective action taken by the MAA in response.

Paragraph 29 of the Decision stated that PANS-OPS is applied as the basis for regulation of IFP's but, as in many areas of aviation regulation, compliance with PANS-OPS does not guarantee approval of a procedure by the CAA as other local factors may be relevant which require alterations and appropriate mitigations to be put in place. Paragraph 30 stated –

On the topic of aeronautical information and the MIL AIP, the CAA was satisfied that civil aircraft operators had ready access to all the information required by civil operators to use RAFN. That included both general information and relevant aeronautical information specific to the aerodrome. Publication of the updated Safety Notice now clearly signposted civil operators to the relevant safety information for RAFN, including that provided in both the AOHL and the DAM. On the concern over data corruption, the CAA stated its satisfaction that the runway declared distances maintain their integrity between the 2022 Measured Height Survey Data [“theSurvey Package”] and the MIL AIP. The CAA was also satisfied that climb gradients and IFP minima maintaintheir integrity between the IFP Design Report and the MIL AIP.

On the topic of the exemptions approved by the MAA, the CAA drew attention to its regulatory approach founded on the 2015 Judgment and set out in paragraph 33 of the Decision. At paragraph 51 the CAA said -

On the topic of runway declared distances, the CAA referred to the SLC Report’s stated purpose which was to determine runway distances at RAFN that would be compliant with the regulatory approach applied to licensed aerodromes such as Oxford, Farnborough and Biggin Hill. At paragraph 53, the CAA drew attention to the position approved at [46] in the 2015 Judgment, that the assessment of risk for civil use of government aerodromes will of coursebe informed by the CAA’s approach to safety at licensed airports, but it does notfollow that CAP 168 must be applied at RAFN or any other government aerodrome. Nor, in deciding whether there is a requisite degree of safety for civil use of a governmentaerodrome, is the CAA bound to impose the same conditions as apply to a licensed civilairport operator.

At paragraph 54 of the Decision, the CAA stated –

Under the topic heading “IFPs (design and safeguarding)”, the Decision considered near in obstacles and trees and other obstacles at RAFN.

The CAA proceeded on that basis that the FN Report’s reference to near in obstacles penetrating the TOCS corresponded in PANS-OPS to “close in” obstacles. Paragraph 60 stated that the CAA was satisfied that the published gradient is calculated on the basis of the requiredPANS-OPS minimum obstacle clearance. The FN Report had added an additional vertical tolerance of 1-3m to theminimum obstacle clearance required by PANS-OPS. That additional verticaltolerance was not required by PANS-OPS. Once that additional vertical tolerance was excluded, the published data for RAFN was accurate.

The CAA said that as the relevant survey data sets are publicly available for flightplanning, there was no force in the Claimants’ contention that near-in obstacles are technicallyinvisible to flight despatchers and will not be considered in pre-flight aircraft performancecalculations.

Turning to trees and other obstacles, paragraph 68 of the Decision stated that the CAA wassatisfied that by excluding the additional vertical tolerance unnecessarily applied by the FN Report, only one obstacle remained which required furtherinvestigation. Paragraph 69 stated –

Tree management was considered in paragraphs 70 to 72 of the Decision –

The final topic considered in the Decision was obstacle marking and illumination. Paragraphs 75 and 76 stated that –

The Decision concluded that –

I have briefly summarised the current position in relation to the observations raised by the CAA in Oversight Report 2 earlier in this judgment.

The Claimants contend that the CAA has failed to carry out a rational assessment of the safety of civil aviation at RAFN. The CAA has failed to assess both the extent to which the obstacle environment at the aerodrome deviates from aviation norms as set out in CAP 168 and PANS-OPS and whether such deviation is acceptable in order to maintain safe operation of civil aviation to and from RAFN.

It was submitted that the CAA had accepted the need to assess the extent to which civil aviation operations at RAFN departed from the regulatory standards set in CAP 168 and PANS-OPS which CAA applies in relation to licensed aerodromes. The CAA had recognised that CAP 168 and PANS-OPS should form the basis of its assessment of safety at government aerodromes. In order rationally to follow that approach to assessment, the CAA needed to inform itself of the extent to which operating conditions for civil aircraft at RAFN departed from those regulatory standards, in order to be in a position properly to judge whether such departures resulted in a safe operating environment. In the absence of having carried out that gap analysis, there was an obvious gap in the CAA assessment in the Decision.

The Claimants relied on established principles of public law –

The Claimants submitted that there were unexplained gaps in the CAA’s analysis in the Decision of the specific safety concerns raised in their letter of 10 January 2024. The CAA had failed to address the obstacle environment at RAFN in a meaningful way, taking account of the concerns raised by the Claimants and in the technical reports submitted in support of those concerns. There was no consideration of the need to reduce declared runway distances. The CAA had placed unquestioning reliance upon exemptions approved by the MAA, without fulfilling its duty of inquiry into whether those exemptions resulted in an unsafe operating environment for civil, as opposed to military, aircraft. The CAA’s assessment of near in obstacles had been too narrow and lost sight of the overarching question whether the obstacle environment taken as a whole was simply unacceptable when considered against the benchmark of the standards set in CAP 168. The CAA had failed reasonably to consider the safety implications of the acknowledged VSS penetrations, resorting to the ineffective requirement to carry out an aeronautical study, still not yet satisfactorily completed.

The Claimants contended that Mr Ngai’s technical evidence in his witness statements was an impermissible attempt ex post facto to overcome the gaps and deficiencies in its assessment in the Decision itself: see R v Westminster City Council ex parte Ermakov (1996) 28 HLR 819, 833 and R (MPI) v Secretary of State for Defence [2024] EWHC 410 (Admin) at [144]-[145]. Moreover, as Mr Hartland explained, in acquiescing in the obstacle environment at RAFN the CAA continued to ignore the practical realities of the risk of pilot error and unfamiliarity with local conditions, mechanical failure and the limitations of the published information on which aircraft operators rely.

The Claimants submitted that the CAA had failed to make reasonable inquiries or to take account of relevant information as to the extent of departures from CAP 168 and PANS-OPS, the nature and location of each obstacle and the seriousness of its infringement. The CAA had failed to engage with the critical question whether the obstacle environment at RAFN rendered the aerodrome unsafe for civil aviation resulting the need to reduce declared runway distances. Having acknowledged CAP 168 as the policy basis for assessing safety of civil aviation at RAFN, the CAA had failed to assess and to justify departures from that policy.

The CAA is the regulatory body responsible for the safety of use of RAFN for civil aircraft operations. Ground (1) is essentially a rationality challenge to the CAA’s assessment of the safety concerns raised by the Claimants in their letter of 10 January 2024. In carrying out that assessment, the CAA acted as an expert and experienced regulator with statutory responsibilities for the safety of civil aviation at both licensed and government aerodromes under the 1982 Act and the ANO. The matters raised by the Claimants in their letter were scientific and technical in nature. The Claimants founded those concerns upon the four technical reports prepared by experts which were submitted to the CAA under cover of their letter. Consideration of those matters by the CAA required the assignment of its specialist personnel to liaise with their counterparts in the MAA and to undertake highly technical analyses of flight procedures. The matters raised by the Claimants also required the CAA and its specialist personnel to make risk assessments informed by their expertise and experience of civil aircraft operations through the practical performance of the CAA’s regulatory functions.

In R (Mott) v Environment Agency [2016] 1 WLR 4338 at [77] the Court of Appeal said that a reviewing court should be very slow to conclude that an expert and experienced decision-maker assigned the task by statute has reached a perverse scientific conclusion. At [70], the court said that it was not the function of the court to form its own view as between the views of different experts in a technical area. The proper function of the court on judicial review of the decision is to consider and to determine the rationality of the decision. In R (Friends of the Earth Ltd) v Secretary of State for International Trade [2023] 1 WLR 2011 at [57] the Court of Appeal cited Mott’s case as authority for “a wider margin of appreciation in decision-making involving the application of scientific knowledge or expertise”.

In my view, that approach applies in this case. Mr Béar KC drew my attention to [63]-[64] in Mott’s case, where the court said that while a regulatory body is clearly entitled to deploy its experience, technical expertise and statutory mandate in support of its decisions, and to expect a court considering a challenge by judicial review to have regard to that expertise, it is also necessary for the decision-maker, when faced with such a challenge, to provide a clear explanation to the court. At [64] Beatson LJ said –

Mr Béar submitted that the CAA had failed to provide such an explanation in the present case. I do not accept that submission. In the present case, the evidence of Mr Gray provides a clear explanation of the safety assessment carried out by the CAA in response to the Claimants’ concerns. Mr Gray has explained the safety assessment framework, the CAA’s arrangements for investigating the Claimants’ concerns, the outcome of that investigation as reported in the Decision and the action since pursued by the CAA through the observations made in Oversight Report 2 which resulted from that investigation. Mr Ngai has explained his role in the CAA’s investigation of the Claimants’ safety concerns. He was responsible for considering the concerns relating to aeronautical information and AIP, declared runway distances and IFP design and safeguarding. Mr Ngai gives a detailed account of his analysis of those concerns, explaining the relevant technical concepts, the sources of data available to him, his expert and technical assessments and explaining his response to the expert and technical reports relied upon by the Claimants. I am satisfied that the evidence of Mr Gray and Mr Ngai has provided the court with a sufficient explanation of the scientific and technical analysis which lies behind the CAA’s assessment in the Decision of the safety concerns raised by the Claimants.

Nor do I accept the Claimant’s argument that Mr Ngai’s evidence should be seen as an impermissible attempt to remedy or to supplement deficient reasoning in the assessment set out in the Decision itself. Given the need, as stated by the court at [64] in Mott’s case, for an expert regulatory body to give a sufficient explanation of technical and scientific matters relating to its decision to enable the court to judge whether it has acted irrationally, it is unsurprising that the CAA has sought to assist the court through the evidence of Mr Ngai. In my view, considered against the analysis given by the court at page 833 in Ermakov’s case, Mr Ngai’s evidence plainly falls within the category of proper elucidation of the technical and scientific analysis which underpins the safety assessment set out in the Decision itself.

RAFN has been notified by the CAA as available for use for civil aviation, without conditions, since 2002. It was so notified at the time of the 2015 Judgment. In essence, when considered against the statutory framework set by the relevant provisions of the 1982 Act and the ANO, the Claimants’ purpose in raising the concerns set out in their letter of 10 January 2024 was to secure a review by the CAA of the notification of RAFN under article 211 of the ANO, with a view either to that notification now being withdrawn or conditions now being imposed by the CAA. A particular change in operating conditions for civil aircraft at RAFN which the Claimants sought to achieve was a reduction in the declared runway distances for both Runways 07 and 25.

The proper approach for the CAA to follow in discharging its responsibility to assess the safety of RAFN for civil aviation was addressed by Popplewell J in [43] to [46] in the 2015 Judgment. I have set out those paragraphs earlier in this judgment. The Claimants did not seek to challenge the analysis given in those paragraphs. In carrying out its review of the safety environment at RAFN in response to the concerns raised by the Claimants, the CAA followed the approach stated by Popplewell J in those paragraphs. That is made clear in the Decision. In my judgment, the Claimants were correct to do so.

The following principles are established in [44] to [46] of the 2015 Judgment –

In my judgment, the CAA’s approach in the Decision to assessment of the Claimants’ safety concerns is in accordance with those principles. The Claimants core contention is that the CAA ought to have undertaken, but have failed to undertake, a gap analysis which assessed and evaluated the extent of departures from the standards applicable to licensed aerodromes in CAP 168 and PANS-OPS. There was, however, no obligation in law for the CAA to follow that approach. As is clear from the assessment set out in the Decision, the CAA did address the right question. The CAA investigated whether in the light of its consideration of the Claimants’ concerns, RAFN continued to provide for safe civil aircraft operations.

In order to answer that question, the CAA sought and obtained information from the MAA and the Aerodrome Operator. The CAA commissioned technical and scientific advice from its specialist personnel. The CAA reviewed the published aeronautical information in respect of RAFN in the MIL AIP, the DAM and the AOHL. The CAA undertook a safety assurance visit to the aerodrome. The CAA and its specialist personnel interrogated relevant survey and technical data obtained from publicly available sources such as the MIL AIP and in response to requests made by the CAA via the GACG.

In the light of the principles stated in [46] of the 2015 Judgment, the Claimants’ argument that the CAA’s failure to undertake a gap analysis constituted an unexplained and unjustified departure from its policy in CAP 168 goes nowhere. The CAA is not required to follow or to apply CAP 168 in making a safety assessment of a government aerodrome in the context of fulfilling its responsibilities under article 211 of the ANO. In paragraph 31 of the Decision, the CAA stated that it used the standards in CAP 168 and PANS-OPS as the basis for assessment. It does not follow that in failing to provide a gap analysis in the Decision in relation to departures from those standards, the CAA has departed from its policy in CAP 168. The CAA’s stated approach to assessment in paragraph 33 of the Decision is in full accordance with the principles stated in [46] of the 2015 Judgment.

The Claimants sought to substantiate their contention that the CAA acted unreasonably in failing to engage with or to confront the issues raised in their letter of 10 January 2026 by reference to a series of specific issues.

The Claimants had commissioned the SLC Report in order to determine runway distances at RAFN that would comply with the standards applicable to licensed aerodromes, on the basis of the obstacles identified in the CAP 1732 survey carried out in April 2023. In paragraphs 52 and 53 of the Decision the CAA stated, correctly, that those standards did not apply to RAFN as a government aerodrome. The CAA quoted the relevant passage in [46] of the 2015 Judgment. The CAA went on to state that the runway declared distances in the MIL AIP for RAFN had been reviewed and found to be both consistent with the Survey Package and accurate.

The Claimants argue that the CAA failed to grapple with the key point of the SLC Report, which was that the obstacle environment at RAFN nevertheless gave rise to the need to reduce the runway declared distances, particularly given the extent of penetration by trees and buildings of both the VSS approach to Runway 25 and the TOCS for Runway 07 (i.e. from and to the east of RAFN).

I do not accept that argument. The assessment in the Decision is focused upon the safety characteristics of RAFN for civil aviation, in respect of which the obstacle environment affecting approach to take-off from the runways is a primary consideration. As stated in [44] of the 2015 Judgment, the CAA was entitled reasonably to rely on the detailed aeronautical information published by the MAA, including the DAM and the AOHL. The CAA was entitled to rely on the assessment of differences from ICAO SARPS. The CAA’s assessment in the light of that information was that the MIL AIP contains all the information required by civil operators to use RAFN. In order to assure awareness of that information, on 7 March 2024 the CAA published the update Safety Notice which signposts civil operators to the relevant safety information for RAFN. That safety information includes the details of obstacles listed and explained in the AOHL and the waivers and exemptions detailed in Annex F of the DAM. It was both consistent with the principles stated in the 2015 Judgment and reasonable for the CAA to base its safety assessment on those matters. I note that as recorded in paragraph 30 of the Decision, the CAA included an observation in Oversight Report 2 correcting a chart in the MIL AIP which inaccurately stated that RAFN was compliant with PANS-OPS. It is nevertheless clear that the CAA was not persuaded by the SLC Report, that there was a need on safety grounds to shorten the runway declared distances at RAFN. That was a reasonable judgment for CAA to make.

The Claimants are incorrect in their submission that the CAA failed to deal with the issues raised by the FN Report. Paragraphs 56 to 74 of the Decision respond to those issues. It is clear from those paragraphs of the Decision that the CAA and its specialist personnel gave proper consideration to the analysis set out in the FN Report. Further elucidation of the technical work done in response to the FN Report is given by Mr Ngai in paragraphs 31 to 38 and 41 to 53 of his first witness statement. The key point discussed in paragraphs 60 and 68 of the Decision is that the FN Report’s assessment of the minimum obstacle clearance required under PANS-OPS guidance was founded upon an additional vertical tolerance of 1 to 3 metres. Mr Ngai’s evidence is that additional vertical tolerance is not a requirement for IFPs at civil aerodromes. He explains that the elevation of obstacles stated in the published aeronautical data for RAFN is a value which is accurate to 3 metres at a 95% confidence level. The FN Report added the 3m tolerance to the elevation of obstacles when that 3m tolerance is already inherent in the method. The FN Report has, therefore, assessed any VSS penetrations on the basis of the highest possible height of the obstacle, rather than the value required by CAP 1732 expressed to 3m accuracy.

In paragraph 53 of his first witness statement, Mr Ngai says –

Mr Ngai explains that in line with ICAO guidance, IFPs for civil aerodromes are subject to periodic review to ensure that changes in technical criteria and the obstacle environment are reflected in the instrument flight procedures. In the UK, periodic reviews are required to be carried out no less than once every five years. There are no current MAA regulatory requirements on the frequency of IFP reviews. It is however the CAA’s understanding that periodic reviews of military aerodromes are triggered by the annual survey. That accords with Commander Bond’s explanation of the arrangements at RAFN for the annual survey to be carried out by Pell Frischmann and the IFPR to be produced by Osprey. In his witness statement, Mr Muir states that the measurements taken by PellFrischmann when conducting the annual survey are more accurate than those required by the regulatory standards.

The Claimants criticise the CAA’s reliance on the exemptions approved by the MAA, to which reference is made in paragraph 51 of the Decision. In that paragraph, the CAA stated that it takes those exemptions into account when assessing the overall safety environment but “has no jurisdiction over the issue of such exemptions”. The Claimants contended that there was no evidence to show that the CAA had itself inquired into the safety risks posed by the obstructions whose presence was the subject of those exemptions approved by the MAA. That was argued to be both in breach of the CAA’s duty of reasonable inquiry and a failure reasonably to confront and to grapple with the risks to civil aircraft posed by the obstacle environment at RAFN.

In my view, the CAA’s approach on this point was consistent with the approach approved by Popplewell J at [44] of the 2015 Judgment. It is obvious both from the contents of the DAM and the AOHL, to which I have referred above, that the MAA has assessed the safety risks resulting from the presence of the legacy buildings, the perimeter structures and the surrounding roads. Those obstructions are permanent features of the built environment within or in close proximity to RAFN. They have been present throughout the period since RAFN was notified as a government aerodrome in 2002.

In paragraph 33 of the Decision, the CAA stated that it must assess differences from ICAO SARPS or CAP 168 standards at RAFN in the light of the specific conditions at the aerodrome and the mitigations in place to address those differences. Further, the CAA “considers any waivers and exemptions” from RAs together with their respective mitigations. The relevant exemptions are identified in paragraph 67.

Paragraph 51 of the Decision states that the exemptions were issued by the MAA in accordance with MAA 003. MAA 003 requires an approved safety assessment to be conducted, which the CAA takes into consideration when assessing the overall safety environment. The CAA is entitled reasonably to rely on the assessment of risk carried out by the MAA under that body’s own regulatory procedures. The CAA is not under a legal obligation to carry out its own assessment of risk in order lawfully and reasonably to fulfil is responsibilities to assess safety for civil aviation at RAFN.

Those conclusions are unaffected by the regulatory standard of ALARP applied by the MAA when approving an exemption under MAA 003. As Ms Gemma White KC submitted, the regulatory guidance in MAA03 is that waivers and exemptions must be supported not only by acceptance that any residual risk is ALARP but also, that the associated risk is tolerable. The CAA will be well aware of the MAA’s standards, when taking exemptions approved against those standards into account in assessing the overall safety environment at RAFN. ALARP is a familiar and fundamental concept in risk assessment for the purposes of health and safety regulation in the UK. It is deployed by the CAA itself in CAP 168, in the context of detailed guidance in Appendix 3I on the assessment of the risk of aircraft undershooting or overrunning a runway: see ibid. at paragraph 18.

In deciding that there should be an aeronautical study in respect of VSS penetrations, the CAA acted consistently with the guidance given in paragraph 5.4.6.4 of PANS-OPS Volume 2 (which I set out below in the context of ground (1A)). It was both in accordance with the principles approved in the 2015 Judgment and reasonable for the CAA to decide to require RAFN to undertake the required aeronautical study. That requirement has been taken forward by the inclusion in Oversight Report 2 of observations ADR.5615 and ADR.5616 in respect of Runway 07 and Runway 25 respectively. In each case, the reason given for the observation was that a number of obstacles penetrate the runway VSS, in circumstances which would call for an aeronautical study were RAFN to have been a licensed aerodrome, in order to identify risks posed by those penetrations and mitigating measures. It is obvious that the CAA gave proper and reasonable consideration to whether that was a sufficient response to the existence of obstructions penetrating the VSS in relation to each runway. Such a consideration is a matter for the judgment of the CAA as regulator informed by the advice of its specialist personnel. There is no force in the argument that the CAA was under an obligation, acting reasonably, to commission or to undertake that study itself. Such a requirement would, again, run counter to the principles stated in the 2015 Judgment.

The tree management regime at RAFN is also the subject of an observation, ADR.5631, included in Oversight Report 2. The recommendation is that RAFN should develop and keep up to date a record of tree maintenance work to create an auditable trail to show when, why and how trees that penetrate protected surfaces were managed. In paragraph 70 of the Decision, the CAA states that the MAA has provided safety assurance in relation to trees penetrating protected surfaces in the same way that the operators of civil aerodromes are able to seek approval from the CAA in relation to particular penetrations. In paragraph 66 of his first witness statement, Mr Ngai gives examples of such approvals being given by the CAA at Farnborough, Biggin Hill, Oxford Airport and Inverness. That regulatory practice is consistent with the approach stated in paragraph 4.2 of CAP 168 and the more specific advice given in paragraph 4.52 thereof.

Paragraph 71 of the Decision records that during its assurance visit in June 2024, the CAA saw and reviewed the Tree Management Plan for RAFN. The CAA said that the mitigation provided for the presence of trees is that they are noted in the AOHL with a list of mitigating actions. That is correct. Paragraph 72 of the Decision states that the CAA also raised the issue of tree reduction with the DIO. The CAA’s stated judgment was that it was satisfied that it did not currently need to take any further regulatory action in respect of trees at RAFN beyond those matters.

In summary, the CAA had informed itself through a site survey, had apprised itself of and reviewed the published AOHL in respect of tree obstacles and mitigating activities and had given advice on the proper management of trees, including the promulgation of an observation in Oversight Report 2 requiring further action by the aerodrome operator. It is again obvious that the CAA gave proper and reasonable consideration to whether that was a sufficient response to the presence and management of trees penetrating the VSS approach to Runway 25. That was a matter for the judgment of the CAA as regulator informed by the advice of its specialist personnel.

My overall conclusion is that ground (1) is arguable. However, for the reasons given and applying the approach to be followed by this court as stated in Mott’s case, I have not been persuaded that the Claimants’ contentions under this ground have been made out. In my judgment, the Claimants have not made good their case that in reviewing the safety of civil aviation at RAFN in the light of the Claimants’ concerns, the CAA failed in its duty of reasonable inquiry, departed from its published policy or failed to confront the issues raised, leaving unexplained gap in its reasoning or analysis. It is true that the CAA and its specialist personnel disagreed with aspects of the four technical reports relied upon by the Claimants, and indeed with Mr Hartland’s report. It is not, however, the proper function of this court to adjudicate on those matters. It is sufficient for this court to conclude, as I do, that in the Decision the CAA carried out its assessment of the Claimants’ safety concerns reasonably and in accordance with the principles approved in the 2015 Judgment. Ground 1 is rejected.

The issue under this ground is whether the CAA failed to give adequate reasons for its decision on the safety concerns raised by the Claimants.

There was some discussion in the pleadings as to whether the CAA was under a duty to give reasons. The Claimants submitted that this was a case in which that duty arose in the light of the principles stated in R (Oakley) v South Cambridgeshire District Council [2017] 1 WLR 3765 at [30]-[32]. However, it was not in dispute that in promulgating the Decision the CAA had volunteered its reasons for the conclusions it had reached in response to the Claimants’ concerns. There are numerous authorities for the proposition that where a public authority gives reasons voluntarily for an administrative decision in the exercise of statutory powers, the court will review the adequacy of the reasons given by applying the same standard as would apply in the case of a duty to give reasons: see De Smith’s Judicial Review 9th Edition (2023) at paragraph 9-145 and the cases there cited. It was not suggested that I should follow a different approach in principle in the present case.

The standard of adequacy is well established. The classic formulation is that given in In Re Poyser and Mills’ Arbitration [1964] 1 QB 467, 478 –

The authorities were reviewed by the House of Lords in the context of planning decision-making in South Bucks District Council v Porter (No 2) [2004] 1 WLR 1953 at [24]-[36]. Amongst the many judicial observations surveyed in those paragraphs are that the reasons need not be lengthy. There is no obligation expressly to address every material consideration or every point raised by the parties. It is important to have in mind that reasons are directed at parties who are aware of the background and the main issues which the decision-maker needs to resolve in order to make its decision. There is no duty to give reasons for reasons.

The Claimants submitted that the reasons given in the Decision were inadequate in failing to explain to the reader why, notwithstanding the presence of the numerous obstacles at RAFN to which the Claimants had drawn attention both in their letter and the reports submitted in support of their safety concerns, the CAA had reached the conclusion that RAFN should continue to be notified without conditions for civil aviation. As a result of the inadequacy of the explanation offered by the Decision, it was not possible for the reader to be satisfied that the CAA had fulfilled its responsibilities as regulator of RAFN for that use.

I am satisfied that the reasons given by the CAA in the Decision were sufficient to address the concerns raised by the Claimants. The CAA had informed the Claimants of the approach which it was to take for the purposes of considering and responding to those concerns. The Decision was structured in accordance with that stated approach. Each of the principal issues raised by the Claimants and their submitted reports was addressed in the Decision. Reasons were given in the Decision for the CAA’s conclusions on each of those principal issues. As I have already found in discussing ground (1) above, the CAA’s analysis of the safety of civil aircraft operations at RAFN was focused upon actual operating conditions at the aerodrome, including the presence of obstacles and the aeronautical information available to aircraft operators. The CAA’s assessment was guided by the principles stated in the 2015 Judgment. The Decision was properly supported by the technical and expert analysis carried out by the CAA’s own specialist personnel. There were no unexplained gaps in the CAA’s reasoning in the Decision. The Decision explains those safety measures which the CAA judged to be appropriate in response to the Claimants’ concerns; and which have been taken forward through the observations stated in Oversight Report 2.

In my judgment, there is no substance in the Claimants’ contentions under this ground. The reasons given in the Decision are demonstrably sufficient to meet the legal standard of propriety, adequacy and intelligibility. I refuse permission on this ground. Had I granted permission, I should have rejected ground (2) as lacking any substantial merit.

The issue under ground (3) is whether the CAA has unlawfully delegated to the GACG, that is to the CAA and the MAA acting jointly, any decision as to whether a Government aerodrome should no longer be notified under article 211 of the ANO (or any change made to conditions imposed under article 211 in respect of that aerodrome).

It is an established principle of administrative law that a statutory power of decision-making must be exercised by the person on whom the power has been conferred: see Shahid v Scottish Ministers [2016] AC 429 at [68]. In the 2015 Judgment at [43], Popplewell J held that it is the responsibility of the CAA to decide whether to notify, or to continue to notify with or without conditions, a Government aerodrome, exercising the power conferred by article 211 of the ANO. The CAA may not lawfully delegate that decision to the MAA. Nor may the CAA delegate that decision to a decision-making body consisting of the CAA and the MAA acting jointly. It is a decision which rests with the CAA alone.

The Claimants submitted that, contrary to those principles, the terms of the Agreement which forms part of the MoU between the CAA and the MAA unambiguously delegate the decision whether to revoke or to amend the notification of a Government aerodrome to the GACG. Since the GACG cannot act without the approval of the MAA, that amounts to an unlawful delegation by the CAA of its decision-making function for which it bears sole statutory responsibility under article 211 of the ANO.

I am unable to accept that this is the effect of the Agreement.

The Claimants found their argument on the terms of paragraph 18(a)(ii) of the Agreement –

That paragraph, however, is to be read and understood in the context of the terms of the Agreement read as a whole. In particular –

Reading the Agreement as a whole, and with particular regard to those provisions to which I have referred above, it is clear that the effect of paragraph 18(a)(ii) of the Agreement is not to delegate the CAA’s responsibility for notification decisions made pursuant to article 211 of the ANO to the GACG (and thereby to the CAA and the MAA acting jointly). The stated purpose of the Agreement is to facilitate the performance by the CAA of its statutory functions under the ANO in relation to the use of Government aerodromes for civil aviation. Central to those statutory functions is the CAA’s responsibility for the notification of such aerodromes for civil aircraft operations in accordance with article 211 of the ANO. As Ms Monica Carss-Frisk KC submitted, the Agreement proceeds and is predicated on the premise that the CAA is the body with sole statutory responsibility for the exercise of the powers conferred by article 211 of the ANO. In my view, it is obvious that paragraph 18 of the Agreement, which is headed “Methods of Communication/Interface”, is concerned to give practical effect to the lawful process of collaboration countenanced by Popplewell J at [44] in the 2015 Judgment. It is both consistent with the principles there stated and with the CAA’s proper performance of its statutory functions that the CAA should receive the considered judgment of the GACG under paragraph 18(a)(ii) of the Agreement, prior to deciding for itself whether to take action pursuant to article 211 of the ANO. That does not amount to an unlawful delegation of the CAA’s statutory decision-making function.

There is no substance in the Claimants’ contention that in this case the CAA has in fact abdicated its decision whether to continue to notify RAFN as a Government aerodrome, with or without conditions, to the GACG and via that body to the MAA. The CAA’s investigation and assessment of the Claimants’ safety concerns have been informed by its consideration of work done by the GACG and material provided by or through the MAA. That is entirely consistent with the principles stated in [44]-[46] of the 2015 Judgment.

I grant permission in relation to ground (3). For the reasons I have given, however, ground (3) is rejected.

Under this ground, the Claimants contend that the CAA and the Secretary of State have misinterpreted PANS-OPS in reading paragraphs 5.4.6.4 and 5.4.6.6.1 of PANS-OPS Volume 2 Chapter 5 as permitting the disregard of penetrations of the Obstacle Clearance Surface [“OCS”] by obstacles whose height is less than 15 metres above the runway threshold.

PANS-OPS Volume 2 Chapter 5 “Final Approach Segment” includes guidance on obstacle clearance altitudes and heights. Section 5.4.6 gives detailed guidance on protection for the visual segment of the approach procedure from obstacles. All new straight-in instrument approach procedures published since March 2007 are required to be protected for obstacles in the visual segment.

For that purpose, a “Visual Segment Surface”[“VSS”] is defined both laterally and vertically. Mr Ngai explains that a VSS is a notional sloping surface within an instrument approach procedure which needs to be monitored and kept clear of any penetration by obstacles. An instrument approach procedure is a set of predetermined manoeuvres using flight instruments and navigation systems designed to guide an aircraft from its initial approach to a point where a visual landing is possible.

Paragraphs 5.4.6.4 to 5.4.6.6 state –

Paragraph 5.4.6.6.1 then states –

The Claimants read these paragraphs as prohibiting, for the purposes of assessment, any penetration of the OCS by obstacles; whilst permitting penetration of the VSS by obstacles with a height less than 15 metres above the threshold to be disregarded. The CAA and the Secretary of State say that the Claimants’ interpretation falls into the error of reading paragraph 5.4.6.6.1 in isolation. The CAA and the Secretary of State argue that paragraph 5.4.6.6.1 must be read in the context of and together with paragraphs 5.4.6.4 to 5.4.6.6. The guidance in paragraph 5.4.6.6 applies only if the VSS is penetrated by obstacles, for which purpose obstacles with a height of less than 15 metres above the runway threshold may be disregarded. Penetrations of the OCS only fall to be assessed in a case where the VSS is also penetrated. It follows that the effects of these paragraphs, read together, is that the 15 metre disregard applies indirectly, via the VSS assessment, to the OCS when applying the guidance in paragraph 5.4.6.6.1.

It is necessary to address the issue between the parties as to the correct approach in principle to be followed in addressing that issue of interpretation.

PANS-OPS is promulgated under the auspices of the ICAO. Under article 44 of the Chicago Convention, the aims and objectives of the ICAO are to develop the principles and techniques of international air navigation; and to foster the development and planning of international air transport. The ICAO’s work programmes are directed by the ICAO Council, a body established under article 50 of the Chicago Convention and composed of 36 member states elected by the ICAO Assembly. The ICAO Council has established the Air Navigation Commission [“the ANC”] as the ICAO’s technical body, under article 54(e) of the Chicago Convention. The ANC considers and recommends SARPs and PANS guidance for adoption or approval by the ICAO Council. The ANC’s duties include establishing technical sub-commissions, one of which is the Instrument Flight Procedures Panel [“IFPP”].

The ICAO Council has issued Directives to panels of the ICAO, dated February 2024. Paragraph 1.2 of the Directives states –

The IFPP’s terms of reference state –

The IFPP’s stated objectives are –

Those objectives include new IFP design criteria to address improvements in air navigation; evolving aircraft capabilities and new operational concepts; instrument flight procedure oversight requirements, harmonization of charting criteria, databases and avionics systems guidance with IFP design standards and the facilitation of an efficient communication between ATC and flight crews; and necessary consequential amendments to impacted Annexes and ICAO Documents as a result of changes to IFP design SARPS and criteria.

The IFPP’s terms of reference require that it should be composed of experts involved in the design of instrument flight procedures or the operational use of these procedures and associated requirements with background in both conventional and performance-based navigation. The IFPP is required to coordinate its work with the various groups of experts responsible for other Annexes and disciplines, as appropriate. The Directives issued by the ICAO Council state the following requirement in respect of decision-making by ANC panels –

PANS-OPS has not been incorporated into domestic law.

The Secretary of State has given directions to the CAA pursuant to section 6(2)(b)(c) and (d) of the 1982 Act, in order to ensure that the United Kingdom discharges its obligations under the Chicago Convention: see the Civil Aviation Authority (Chicago Convention) Directions 2022 [“the Directions”]. Paragraphs 6 to 10 of the Directions state –

The Specified PANS in the schedule to the Directions include PANS-OPS (Doc 8168) Volumes I and II.

Paragraph 6 of the Directions requires that when exercising its statutory functions, the CAA must ensure that it acts consistently with the obligations placed on the United Kingdom under the Chicago Convention. Mr Ngai’s evidence is that the CAA applies PANS-OPS as the basis for regulation of IFPs.

Mr Ngai states that he became a member of the IFPP in 2024. Since becoming a member, he has contributed to technical working groups, panel discussions and votes on the implementation of technical criteria relevant to IFP design. Mr Ngai endorses the CAA’s and the Secretary of State’s interpretation of paragraph 5.4.6.6.1 of PANS-OPS Volume II and considers that the Claimants’ interpretation is “plainly wrong”. Mr Ngai gives his reasons in paragraph 55 of his first witness statement –

In his expert report, Mr Hartland explained that he supported the Claimants’ interpretation of the disputed PANS-OPS guidance. In his second witness statement, Mr Ngai referred to correspondence with a colleague at another national aviation regulator with whom he had discussed the interpretation of paragraph 5.4.6.6.1. Mr Ngai states that on 9 July 2025, he received an email from that colleague expressing their personal, informal view that the Claimants’ interpretation may be correct, for similar reasons to those given by Mr Hartland and by reference to an ICAO State Letter introducing the relevant PANS-OPS provisions. That letter stated –

Mr Ngai says that the UK’s response to that State Letter did not respond directly in respect of paragraphs 5.4.6 (including its sub-paragraphs).

In the light of these matters, in paragraph 22 of his second witness statement Mr Ngai states the following proposed course of action –

Following the hearing before me, the parties agreed a note on the IFPP. That agreed note stated –

Against this background, the CAA and the Secretary of State submitted that this court should proceed in accordance with the approach stated by the House of Lords in R (Corner House Research) v Director of the Serious Fraud Office [2009] AC 756 at [44] and [65].

At [44] in Corner House Lord Bingham said –

At [65], [67] and [68] in Corner House Lord Brown of Eaton-under -Heywood said –

At [68] Lord Brown concluded that the furthest the court should go in examining the point of international law in question was to satisfy itself that the public officer had adopted a “tenable view” on that issue. That approach was followed in R (Friends of the Earth Ltd) v Secretary of State for International Trade [2023] 1 WLR 2011 and in R (Save Stonehenge World Heritage Site Ltd) v Secretary of State for Transport [2025] PTSR 726. At [146]-[147] in Stonehenge, the Court of Appeal said –

The CAA and the Secretary of State submitted that this court should apply a “tenability” approach to the dispute as to the interpretation and application of paragraph 5.4.6.6.1 of PANS-OPS in the present case. I accept that submission for the following reasons –

For the Claimants, it was submitted that the “tenability” approach is inapplicable, since PANS-OPS is not a treaty obligation but merely a technical standard or guidance which the CAA has chosen to adopt as a benchmark for its ordinary regulatory functions. The constitutional principle of dualism upon which the authorities relied upon by the CAA and the Secretary of State founded in simply not engaged. Reliance was placed on the established principle of administrative law that the correct interpretation of a policy is a matter of law for the court.

I do not accept that the distinction that the Claimants seek to draw between an unincorporated treaty obligation and the status of PANS-OPS as guidance promulgated under the auspices of the Chicago Convention is a material one. I have explained the role which the international bodies established under the Chicago Convention play in the promulgation of PANS-OPS and the procedural arrangements under that treaty for the review of that technical guidance, with the objective of promoting international standards in civil aviation.

It is, in my judgment, obvious that the task of resolving disputes or difficulties in the meaning and application of such guidance should be vouchsafed to the international bodies established for that purpose under the Chicago Convention, to which the United Kingdom is an original party. Provided that the CAA through Mr Ngai assert a tenable approach to the meaning of paragraph 5.4.6.6.1 of PANS-OPS, it would be wrong in principle for this court to intervene further. I am satisfied that Mr Ngai has done so in paragraph 55 of his first witness statement (and that in his second witness statement Mr Ngai has advanced a tenable basis for disagreeing with Mr Hartland’s alternative interpretation in his expert report).

For these reasons, I decline to intervene on ground (1A).

In the light of my conclusions on the substantive grounds of claim advanced by the Claimants, it is unnecessary for me to address the arguments raised by the Defendants challenging both the Claimants’ standing to bring these proceedings for judicial review and whether the claim was brought promptly.

I grant permission on grounds (1), (1A) and (3). I refuse permission on ground (2). For the reasons I have given, the claim must be dismissed.