US airlines warned Minister for Transport Darragh O’Brien last year that the 32 million annual limit on passengers at Dublin Airport risked breaching international air travel treaties, documents show.

Industry body Airlines for America (A4A) complained to Washington’s department of transportation earlier this year that the passenger cap broke the EU-US Open Skies agreement, and subsequently warned that some Irish flights to the US could be barred as a consequence.

A4A told O’Brien that any move to restrict airline access to Dublin, or to direct traffic to other Irish airports, “would risk breaching the US-EU Open Skies Agreement and undermine the principles of market freedom and competition”, in a letter on April 28th.

O’Brien and the Coalition had by then pledged to remove the controversial passenger limit in the programme for government.

The Minister subsequently published the heads of a Bill that will allow him to axe or amend the limit if the Oireachtas enacts it into law.

A4A chief executive Chris Sununu recently warned the Oireachtas Joint Committee on Transport that the Republic could lose flights to the US if the law is not passed on time and regulators are forced to implement the passenger limit.

Documents released under the Freedom of Information Act show that O’Brien and his officials frequently communicated with A4A about the Dublin cap over the last year.

Sununu wrote to the Minister in October, welcoming his announcement that he intended to publish legislation to remove the cap, saying axing the limit was critical to giving US airlines legal and operational certainty at Dublin.

“The current restrictions are not sustainable under the US-EU Open Skies Agreement and risk undermining the economic benefits that aviation connectivity brings to Ireland,” he stated.

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Open Skies allows US and EU airlines access to each other’s airspace and airports, up to their physical capacity. It bars artificial restrictions on flights.

A4A’s April 2025 letter specifically highlighted reports of efforts to direct US airlines to Shannon Airport and away from Dublin.

Keith Glatz, senior vice-president, international affairs, expressed concern that stakeholders were calling for the redirection of traffic to Shannon from Dublin “not on the basis of commercial demand” but to get around the artificial limit imposed on the capital’s gateway.

Those reports, in The Irish Times, included details of civil servants’ efforts to promote the mid-western airport’s benefits to US carrier Delta, and calls by Fianna Fáil Clare TD Cathal Crowe for measures to encourage airlines to fly to the regions.

Crowe frequently advocates for Shannon. However, airlines and industry bodies told the deputy at recent transport committee hearings that carriers barred from using Dublin would be more likely to choose airports outside the Republic, particularly in Britain.

Planners imposed the limit on terminals one and two in Dublin Airport in 2007 on the basis that the gateway would need a third terminal as it grew towards 40 million passengers a year.

However, since technology has made checking in and security processing more efficient, a third terminal is no longer needed to facilitate growth, but the planning conditions based on the notion remain in place.

Airlines want the Oireachtas to pass the Dublin Airport (Passenger Capacity) Bill 2026 in advance of the summer. This would allow O’Brien to scrap or amend the cap. Failure to do this before an EU court ruling due in the coming months could force regulators to implement the limit, say industry figures.