But Ms Justice Mary Rose Gearty adjourned until Tuesday an application by the airlines to seek a stay on the imposition of the cap. Allocation of landing slots at the airport is due to take place on November 7, the court heard.
The judge was told it was inevitable also that there would be a reference on the matter to the Court of Justice of the EU.
The challenges are against the Irish Aviation Authority’s (IAA) decision to limit Dublin Airport passenger numbers to 25.2 million for the summer 2025 season from late March to October next.
Separate challenges to a 14.4 million passenger limit over the 2024 winter period – from late October to March – is already subject to High Court challenges by Ryanair and Aer Lingus. Dublin Airport Authority, which manages the airport, has also brought a challenge.
Those judicial review proceedings are due to be heard in December.
The IAA is responsible for identifying and allocating an airport’s maximum available capacity in a fair and transparent way in line with EU regulation on slot capacity (the Slot Regulation) at EU airports. The body said it takes account of technical, operational, environmental and local planning constraints.
The US airlines representative association Airlines for America (A4A) is also bringing a separate challenge to the Ryanair and Aer Lingus cases.
Among the orders they are seeking is the quashing of the IAA decision to impose limits on the numbers of passengers, and declarations that the IAA is not and was not entitled to have regard to planning conditions for both airport terminals when determining passenger limits under the Slots Regulation.
They also say there was a failure by the IAA to adhere to a requirement to discuss in detail its decision, prior to making it, with the coordination committee of airlines and the airport authority.
Aer Lingus also says the IAA acted outside its statutory powers and breached its rights under the Constitution and the European Convention and/or its legitimate expectations.
Ms Justice Gearty granted permission to Conor Quinn BL, for Aer Lingus, Martin Hayden SC, for Ryanair and Declan McGrath SC, for A4A, to bring their proceedings on an ex parte (one side only represented) basis.
Mr Hayden said there was “inevitably going to be a reference” to the European courts for a ruling. He said Ryanair stood to lose some €50m from the loss of 550,000 passenger seats and 3,000 slots.
Mr Quinn said Aer Lingus would lose 362,000 seats.
Mr McGrath, for A4A, said that with the slot allocation due to be made on November 7, a decision on stay needs to be made urgently. He also said it would be argued the passenger limit breaches the EU-US Open Skies agreement.
