Aer Lingus Ltd & Ors v Irish Aviation Authority (Approved)

Factual and Procedural Background

This judgment concerns applications for injunctions in judicial review proceedings related to the setting of slot coordination parameters at Dublin Airport under Council Regulation (EEC) No. 95/93 (the Slot Regulation). The Irish Aviation Authority ("the IAA") is responsible for setting these parameters biannually for Summer and Winter seasons, to manage landing and take-off slots where demand exceeds supply. The core dispute involves whether certain planning conditions imposed by An Bord Pleanála on the airport operator ("daa")—specifically, a cap limiting combined terminal capacity to 32 million passengers per annum ("the 32mppa conditions")—constitute relevant technical, operational, or environmental constraints under Article 6 of the Slot Regulation that the IAA must consider when setting coordination parameters.

Previous judicial decisions include a November 2024 ruling imposing a stay on the Summer 2025 Passenger Air Traffic Movement ("PATM") seat cap of 25.2 million passengers and a December 2024 ruling referring legal questions to the Court of Justice of the European Union ("CJEU"). The underlying judicial review proceedings challenge the IAA’s decisions to factor the 32mppa conditions into slot coordination parameters, with applicants including two major airlines ("the airlines") and the Air Transport Association of America ("A4A"), opposed by daa and with the IAA adopting a neutral stance on interlocutory relief.

The present application seeks an injunction preventing the IAA from taking account of the 32mppa conditions in setting coordination parameters pending final determination of the judicial review proceedings. This application is distinguished from prior stay applications as it concerns future decisions yet to be made rather than stays on existing decisions.

Legal Issues Presented

1. Whether the 32mppa planning conditions imposed on Dublin Airport constitute relevant technical, operational, or environmental constraints under Article 6 of Council Regulation (EEC) No. 95/93 for the purposes of setting slot coordination parameters.
2. Whether the court has jurisdiction and should grant interlocutory relief (an injunction) preventing the IAA from taking account of the 32mppa conditions in future coordination parameter decisions pending final determination of the judicial review proceedings.
3. Whether the injunction sought is mandatory or prohibitive in nature and the applicable legal tests for granting such relief.
4. Whether the balance of justice favors granting the injunction given the potential irreparable harm to the airlines and the statutory context of the IAA’s decision-making process.

Arguments of the Parties

Applicants (Airlines and A4A)

• The 32mppa conditions should not be treated as relevant constraints under Article 6 of the Slot Regulation and thus should not be factored into coordination parameters.
• The imposition of PATM seat caps based on the 32mppa conditions causes serious irreparable harm, including loss of historic slots, loss of ad hoc pool slots, significant financial losses, and adverse effects on competition and the national economy.
• Granting the injunction would avoid repetitive, costly judicial review and stay applications for each seasonal decision.
• The injunction sought is prohibitive, restraining the IAA from taking account of one specific factor, and does not compel the IAA to act in a particular way beyond that.

Respondent (Irish Aviation Authority)

• The IAA maintains that the 32mppa conditions are relevant constraints under Article 6 and that it is obliged to consider them in setting coordination parameters.
• However, the IAA adopts a neutral position regarding the interlocutory relief sought and confirms it can carry out its functions without factoring in the 32mppa conditions if ordered by the court.
• The IAA recognizes the practical merits of granting the injunction to provide certainty and avoid repeated litigation and stay applications.
• The IAA opposes any amendments to the injunction that would seek to restrict the relief to preserving historic slots only, as this would interfere more significantly with the statutory process and slot allocation functions undertaken by Airport Coordination Limited ("ACL").

Notice Party (daa)

• daa agrees that the 32mppa conditions are relevant constraints but disputes the manner in which the IAA has applied them.
• daa opposes the injunction, arguing that the court should allow the statutory process to conclude before intervening, to respect the statutory consultation and decision-making framework.
• daa contends the injunction sought is mandatory in nature because it directs how the IAA must perform its functions.
• daa proposes limiting any injunction to protecting existing historic slots, a proposal opposed by the IAA and rejected by the court.
• daa points to ongoing planning applications and enforcement correspondence with Fingal County Council regarding breaches of the 32mppa conditions, emphasizing the regulatory context.
• daa highlights projections indicating that passenger numbers will exceed the 32mppa in coming years without measures to limit growth.

Table of Precedents Cited

Court's Reasoning and Analysis

The court confirmed it has jurisdiction under Order 84, rule 20(8) of the Rules of the Superior Courts to grant interlocutory relief, including injunctions restraining consideration of factors pending judicial review. The distinction between stays and injunctions was clarified, but the same substantive criteria apply.

The court characterized the injunction sought as prohibitive rather than mandatory, as it restrains the IAA from considering the 32mppa conditions rather than directing how the IAA must perform its functions. The court distinguished the present case from authority involving mandatory injunctions compelling specific actions by public bodies.

In balancing the justice of granting the injunction, the court noted the serious and irreparable harm to the airlines if the 32mppa conditions were factored into coordination parameters, including loss of historic and ad hoc slots, financial losses, and adverse effects on competition and the economy. The court found no new material changes since the November 2024 judgment that would justify a different outcome.

The court rejected the argument that it should refrain from intervening until the statutory process concludes, noting that the IAA is likely to continue factoring in the 32mppa conditions and that waiting would lead to repetitive litigation and expense. The court found that the injunction would promote certainty and efficient resolution.

The court also rejected daa's proposed amendment limiting the injunction to protecting historic slots, finding it would amount to a greater interference with the statutory process and was opposed by the IAA.

In conclusion, the court applied the legal principles governing interlocutory injunctions, assessed the balance of convenience and irreparable harm, and found that the injunction should be granted to restrain the IAA from considering the 32mppa conditions pending final determination of the judicial review proceedings.

Holding and Implications

The court granted the interlocutory injunction sought by the airlines, restraining the Irish Aviation Authority from taking account of the 32mppa planning conditions in setting coordination parameters for Dublin Airport pending the determination of the judicial review proceedings.

The injunction will remain in place until further order, with liberty for the parties to apply on 72 hours' notice in the event of material change in circumstances.

The decision directly affects the conduct of the IAA in upcoming slot coordination decisions, ensuring that the disputed planning conditions do not influence those decisions while the legality of such consideration is resolved. No broader precedent was established beyond the immediate relief granted, and the court emphasized respect for the statutory process subject to judicial oversight.