BRUSSELS — Traffic jams on the outskirts of Dublin in the early 2000s triggered a butterfly effect that is turning into a nightmare for Irish aviation and have led to a potential landmark court case that could affect airports across the EU.
The problem dates back to 2007. That’s when local authorities imposed a cap of 32 million passengers per year on the airport, fearing that the growing number of flights would lead to excessive congestion on the M50 highway connecting the airport to the Irish capital.
Back then, the island’s busiest airport handled just 23 million passengers a year, and the cap seemed reasonable.
But last year, Dublin Airport reached 31.9 million passengers, and its operator now wants to get rid of the limit and is challenging it in court, promising to take the case to EU judges.
An EU court ruling could have repercussions across the continent. If the judges scrap the limits it would affect other airports like Rome’s second airport of Ciampino, where the government has imposed a daily cap of 65 flights, or other airports with nighttime flight bans.
Flight caps are also causing political fights at Amsterdam Schiphol and Brussels Zaventem airports, both of which face restrictions to reducing noise pollution.
Until the courts have their final say, Dublin must continue to abide by the cap unless local authorities change or scrap it — a decision that could take years.
“It’s a mess that Ireland should be able to fix,” said Dublin Airport CEO Kenny Jacobs.
No more jams
What especially annoys Jacobs is that the traffic jams that created the situation are long gone.
“Traffic congestion is no longer a problem because the roads have been invested in and we’ve got a very good bus connectivity to the airport,” he said.
This was even recognized by Fingal County Council — the local authority responsible for the airport — which in 2019 noted that “considerable road network improvements have been implemented that provide for improved access to Dublin Airport.”
In addition, the airport has committed to providing more than 35 million bus seats by 2025 to further reduce car traffic from the city.
These efforts are linked to the airport’s application to Fingal County Council to raise the cap to at least 40 million passengers.
“I think and I hope they will make a decision to say ‘yes’ by this Christmas,” Jacobs said. But the final decision is made at the national level, and “the state agency takes years in Ireland [because] anybody could object.”
The hub serves as a home base for Aer Lingus and Ryanair, both of which oppose the passenger cap. Ryanair Group CEO Michael O’Leary has on several occasions described the cap as “stupid,” “bogus” and “idiotic.”
The biggest losers are not the airlines currently operating out of Dublin, but rather potential newcomers blocked by the cap.
Slot allocation is decided by the Irish Aviation Authority (IAA), which schedules traffic at Dublin Airport so it doesn’t exceed the 32 million passenger threshold.
The IAA slot allocation for this winter is being challenged in court by Dublin Airport, Ryanair and Aer Lingus. The case is expected to be heard by Irish judges in December.
In its latest draft capacity plan, announced on Sept. 12 and to be confirmed in October, the IAA proposed “a seat capacity limit of 25.2 million seats” from March 30 to Oct. 25 next year.
The authority noted, however, that “demand for slots for the Summer 2025 scheduling season would significantly exceed the proposed seat cap,” and said airlines that have operated at the airport in the past will be given priority over newcomers.
This rule hurts entrants “like Delta, American Airlines, United and Jet Blue, [who] are unhappy with the slots that they’ve lost” because of the cap, Jacobs said.
U.S. airlines are poised to launch new direct flights between American airports and Dublin, which has been chosen by many Silicon Valley high-tech giants as their EU headquarters — so much so that an area of Dublin where Google and Facebook are based is known as the Silicon Docks.
“How does this sit with [the treaty on] Open Skies between the U.S. and Europe, and with the regulation on trade, free movement of people, and [the] EU slots regulation?” asked Jacobs.
In addition, “two brand-new airlines wanted to start operating at Dublin Airport, which would have created about 300 good jobs, but they can’t get slots,” Jacobs complained in a post on social media.

Economic risks
Irish Finance Minister Jack Chambers agreed that the passenger cap was a “serious risk” to Ireland’s economic growth.
But not everyone thinks the cap should go.
“I don’t buy that,” said Ciarán Cuffe, a former member of the European Parliament from the Greens, in a recent interview when asked about the cap’s economy-chilling effect.
“We want to see good jobs, green jobs in the future. But job creation in Ireland does not depend on endless expansion in aviation,” he said.
As for the idea that the airlines and airport will try to fit within the cap: “Turkeys don’t vote for Christmas,” he quipped.
“It’s very simple: If Michael O’Leary wants to get his €100 million bonus he has to keep pushing for the expansion of aviation, which to my mind is completely insane in the middle of a climate breakdown.”
In addition to green politicians and activists, groups of residents fighting against aircraft noise also strongly object to increasing airport capacity.
With next winter’s slot allocation being challenged in court, Jacobs said, “in December, Dublin Airport, Ryanair, Aer Lingus and the aviation regulator will all be in an Irish court arguing which is more important: Irish planning laws or EU aviation regulation?” He noted that EU rules guarantee airlines their right to use the airport.
“I think an Irish judge is going to say ‘I can’t decide this’ and [the case] is going to go to Luxembourg to be decided” by the Court of Justice of the EU.
That ruling will be watched very closely across the bloc.
“Lots of European regulators in aviation and airports are interested in what’s going to happen with the Dublin cap,” the CEO said.