Airspace in a crowded sky

27 August 2019 by

Lasham Gliding Society Ltd, R (on the application of) v. the Civil Aviation Authority and TAG Farnborough Airport Limited read judgment

The Claimant, the Lasham Gliding Society, challenged a decision by the Civil Aviation Authority, the statutory regulator of UK airspace, to permit the introduction of air traffic controls in airspace around Farnborough Airport, which is presently largely uncontrolled. Lasham Gliding Society (“LGS”) is one of the largest gliding clubs in the world. Its concern was that one of the effects of the CAA’s decision would be to increase the risk of a mid-air collision between its gliders and those aircraft which divert away from any newly controlled airspace around Farnborough Airport into the adjacent uncontrolled zone over Lasham where its gliders fly.

To put it in more detail, LGS argued that as a result of the CAA’s decision, light powered aircraft would be unable to enter their proposed controlled airspace which would compress them into the limited channel of non-controlled airspace near Lasham, thus creating “bottlenecks” that would increase the risk of mid-air collisions (referred to in the judgment as the “Lasham bottleneck” or “Lasham Gap”

LGS challenged the CAA’s decision on the basis that the CAA had misconstrued the Transport Act 2000; was in breach of its duties under the Act and had acted irrationally. The relevant provision is Section 70 which provides, broadly, that “the CAA must exercise its air navigation functions so as to maintain a high standard of safety in the provision of air traffic services, and that duty is to have priority over [the CAA’s obligation to secure the most efficient and expeditious flow of aircraft, to satisfy the requirements of owners of all classes of aircraft and to take account of environmental objectives, national security interests, etc.].”

The Civil Aviation Authority’s (CAA) Airport Modernisation Strategy (2018) set the scene for the present challenge:

Demand for air travel has grown strongly in recent decades, and the Government expects that demand will continue to rise significantly between now and 2050. Growth in demand for air travel means increasing pressure on our airspace.

The response of the Department of Transport was to set out a “strategic case for airspace modernisation” in 2017. These included the capacity for airlines to add new flights, and to

improve access for other airspace users, including the Ministry of Defence, which requires more access to airspace to support a greater number of military aircraft.

LGS made a number of criticisms of the CAA’s Farnborough proposal, including that they had ignored, or not properly understood, the requirements of gliders and the extent of the effect of its proposals on gliding from Lasham. In particular, they submitted that there had been no analysis of the risk that the introduction of controlled airspace would have the effect of diverting light powered aircraft into the “Lasham bottlenecks”, that would significantly increase the risk of mid-air collisions.

Lasham was not alone in its concerns about these proposals. Oddly enough in this context, the MOD shared the same concerns as the gliding society. The MOD operates an RAF base, RAF Odiham, close to the Lasham Gliding Club. RAF Odiham hosts light aircraft as well as gliders. The MOD shared LGS’s concerns about the introduction of airspace controls around Farnborough airport and the increased risk of a mid-air collision in the Lasham Gap. The Interested Party in these proceedings was TAG Farnborough, who took control of Farnborough Airport from the MOD in 2003.

Arguments before the Court

Unfortunately for the applicants, the challenge was based on the most difficult ground for judicial review: irrationality.

LGS submitted that no rational decision maker could have concluded that a high standard of safety would be maintained by the decision under challenge. It was common ground between the parties that 70% of powered light aircraft currently using the uncontrolled airspace around Farnborough would choose not to enter into the newly controlled airspace and that a proportion would fly through the Lasham Gap (or “bottleneck”), which is the densest area of LGS’s gliding operations. LGS recognised that the CAA has experience in the design of airspace which requires technical and specialist knowledge but they argued that the CAA did not carry out or rely on a factual or evidence based analysis which was necessary to enable it to reach a rational conclusion on safety.

The CAA maintained that it had reached a lawful and rational decision. The court, they said, should be slow to second-guess on rationality grounds the conclusions reached by a public body to whom Parliament has entrusted the function of determining regulatory matters of a technical or specialised nature.

There is a great deal of detail at the root of the regulatory system for “controlled” airspace which I will not enter into in this post as they are set out in Thornton J’s enlightening judgment.

The principles for a rationality challenge set a very high bar. As the judge observed,

When a decision is made by a public body in good faith, following a proper procedure and applying conscientious consideration, a Claimant must show more than that a mistake has occurred. It must be shown that the decision was one that could not reasonably have been reached on the material or was otherwise irrational. Facts which have been found by a body charged with making decisions based on their findings of fact are not readily susceptible to challenge. The Court should be wary of invitations to engage in detailed analysis of the phraseology used and drawing fine distinctions between different parts of what may be long and complex reasoning. A Court of review should be concerned with rationality, rather than forming its own view on part of the material available to the decision maker.

The judge therefore did not find sufficient grounds to overturn the CAA’s airspace decision in light of LSG’s arguments. The decision the CAA had taken was highly technical and well within the margin of appreciation the Court should afford to that Authority.

Lasham has advised its members that the new Farnborough airspace will come into effect by early 2020.


Is rationality a test that will survive a society where technological advancements require increasingly specialised regulations? The scope of judicial review, as Thornton J observed,

…is acutely sensitive to the regulatory context. The Courts allow an enhanced margin of appreciation for the exercise of regulatory judgment in technical and specialised areas including educated predictions for the future; specialist judgments and the application of specialised scientific and technical knowledge or expertise (R(Mott) v Environment Agency [2016] EWCA Civ 564).

She favoured the argument on behalf of the CAA that decision taken was “highly technical” and well within the wide margin of appreciation the Court should afford them.

Patrick Naegeli, Chairman of the LGS, observed that this ruling was “a bitter blow to Lasham and the wider general aviation community”.

The difficulties this case raises continues to draw a spotlight on questions surrounding the CAA’s policies and decision-making processes.

[…]It is clear that airspace change is a technical and specialised area of regulation and that Farnborough Airport sits within an area of particularly complex airspace.

[…] Decision making staff at the CAA have skilled and specialist knowledge. So too do the members of LGS who provided witness statements.

Or, put another way, is judicial review on rationality grounds fit for purpose any more, given the spread of areas governed by specialist regulation? The Casemine blog has an excellent article on this question applying to this very case.

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