High Court upholds CAA's safety assessment of civil aviation operations at RAF Northolt, dismissing challenge by private airport operators
In Oxford Aviation Services Ltd and Ors v Civil Aviation Authority [2026] EWHC 1044 (Admin), the operators of Oxford, Biggin Hill and Farnborough airports challenged the Civil Aviation Authority's (“CAA”) decision not to withdraw, suspend or impose conditions on the use of RAF Northolt for civil flights. The claim was brought by operators of competing business aviation airports, who argued that RAF Northolt enjoyed a competitive advantage by operating without the regulatory constraints applicable to licensed civil aerodromes.
The court granted permission on three grounds but dismissed all of them on the merits (and refused permission on the fourth), holding that the CAA had acted lawfully and rationally. The judgment reflects the courts’ reluctance to intervene in the decisions of expert regulators in specialist and technical areas.
Background
RAF Northolt is a Government aerodrome in north-west London. It has been notified by the CAA as available for civil aviation, without conditions, since 2002. The claimants operate private airports at Oxford, Farnborough and Biggin Hill, which service the same class of private business jets that also use RAF Northolt. In January 2024 they wrote to the CAA raising safety concerns about the obstacle environment at the aerodrome and the adequacy of the published aeronautical information available to civil users. The CAA undertook a desktop investigation and a safety assurance visit following which it made 23 observations with recommended corrective actions, the CAA responded in July 2024 concluding that it had not identified any issue requiring it to take regulatory action beyond its ongoing safety assurance processes. The claimants issued judicial review proceedings challenging that decision.
The case was listed as a rolled-up hearing, considering both permission to bring judicial review and the substantive claim at the same time. The court granted permission on grounds 1 (rationality of the safety assessment), 1A (interpretation of international guidance on obstacle clearance) and 3 (unlawful delegation to a joint body with the MAA), but refused permission on ground 2 (adequacy of reasons). All grounds on which permission was granted were dismissed on the merits.
The case followed on from an earlier challenge to the same aerodrome 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”). In that case, the High Court held that although the CAA may rely on technical input from the Military Aviation Authority (“MAA”) when assessing safety at a government aerodrome, it must retain ultimate responsibility for the decision whether to permit civil use and cannot delegate that decision to the MAA. The present case revisited that principle in the context of the CAA’s cooperation with the MAA through the Government Aerodrome Co‑ordination Group (“GACG”).
Key legal grounds
Ground 1: failure to conduct a rational safety assessment
The claimants argued that the CAA had failed to carry out a rational assessment of the extent to which conditions at RAF Northolt departed from the aviation safety norms, and whether those departures were safe. They said the CAA should have carried out what they described as a ‘gap analysis’ comparing RAF Northolt against the benchmarks applicable to licensed civil airports.
The court applied the principle in R (Mott) v Environment Agency [2016] 1 WLR 4338 in which 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". A technical area such as this afforded the decision maker a wide margin of appreciation in making their decision. Here, the CAA had investigated the claimants' concerns through its specialist personnel, carried out a safety assurance visit, reviewed published aeronautical data and raised corrective observations where issues were identified. The court held there was no legal obligation to carry out the gap analysis the claimants wanted. The CAA had asked the right question — whether RAF Northolt remained safe for civil operations — and answered it reasonably.
The court was also satisfied that the CAA had properly considered obstacles, declared distances and tree management. Ground 1 was therefore rejected.
Ground 1A: interpretation of PANS-OPS
The claimants argued that the CAA had misinterpreted international guidance on obstacle clearance (PANS-OPS).
The court declined to determine the correct interpretation itself and instead applied a ‘tenability’ standard, asking only whether the CAA’s interpretation was reasonably open to it. PANS-OPS is international guidance promulgated under the Chicago Convention and has not been incorporated into domestic law, although it is used in practice by the CAA as a technical benchmark. Applying the "tenability" approach from R (Corner House Research) v Director of the Serious Fraud Office [2009] AC 756, the court held that it was sufficient that the CAA's interpretation was tenable, supported by the evidence of its specialist who sits on the relevant ICAO panel. The court noted that the proper forum for resolving any ambiguity is through ICAO's own processes, not domestic judicial review. In any event, by the date of the hearing the remaining identified obstacle had been resolved so there were no longer any relevant obstacles at the aerodrome. Ground 1A was dismissed.
Ground 2: adequacy of reasons
The claimants argued that the CAA's decision letter did not provide proper and adequate reasons for its decision, despite the numerous obstacles at RAF Northolt, the aerodrome could continue to be notified without conditions.
The court held that the reasons given were sufficient. The decision was structured around the issues raised by the claimants, addressed each of them in turn and explained the CAA's conclusions. Permission was refused on this ground. The court added that even had permission been granted, the ground would have been dismissed on the merits.
Ground 3: unlawful delegation
The claimants argued that the CAA had unlawfully delegated its decision-making power to the GACG, and/ or the MAA. Relying on the principles established in the 2015 Judgment, they contended that the CAA must exercise its statutory judgment independently and could not share or transfer that responsibility to a joint decision-making body.
The court rejected that argument. It held that, properly interpreted, the arrangements between the CAA and the MAA preserved the CAA’s ultimate decision-making authority. While the CAA was entitled to seek and take into account the views of the GACG, that did not amount to an unlawful delegation of its statutory function.
Commentary
The decision underscores the high threshold for successfully challenging CAA safety decisions by way of judicial review. Where the CAA can demonstrate a structured safety assurance process and reasoned engagement with technical concerns, the court will be slow to intervene, even if industry participants disagree with its conclusions.
The judgment also confirms that, in highly technical areas, the courts will show particular deference to the regulator, reflecting the approach in R (Mott) v Environment Agency [2016] EWCA Civ 564; [2016] 1 WLR 4338. Disputes over the interpretation of international aviation guidance (such as PANS‑OPS) will not generally be resolved by the courts: it is sufficient that the CAA’s interpretation is reasonably open to it, with the appropriate forum for resolving technical disagreements likely to be the relevant ICAO processes.
A further important clarification is that the court could find no statutory basis requiring government aerodromes to meet CAP 168 standards applicable to licensed civil airports, and the CAA is under no obligation to undertake a formal comparison against those standards when assessing safety in that context.
Finally, the case reinforces that while the CAA may rely on input from the MAA and joint bodies such as the GACG, it must retain and exercise its own independent judgment. Unlawful delegation will only arise where that responsibility is effectively ceded.
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