Passengers have been beset by a massive spike in delays and cancellations over the past 12 months due to industrial action, particularly in France, which has a significant stake in European airspace.

O’Leary last week said Europe’s ATC was “on the verge of meltdown”, with Ryanair having to cancel 1,000 flights in May alone - up from just 43 the same time last year.

Citing official figures, O’Leary said 117,000 European flights were delayed in May, 61% due to ATC staff shortages and strikes, while 56,000 were delayed by more than 15 minutes, up from 14,000 during the same period last year.

Speaking after a meeting with Europe’s transport commissioner Violeta Bulc on Wednesday (June 20), O’Leary and Walsh said the EU Commission was not doing enough to protect flights.

Walsh said EU recalcitrance was “destroying” European air traffic while O’Leary criticised the “lethargy and inaction” of the commission and national governments, the Financial Times reports, with ATC controller nationally.

“Nothing will get in the way of the four freedoms, unless you’re a French air traffic controller,” O’Leary added, joking strikes were still a “national pasttime” in France.

The European Commission, last summer, reported that since 2005, there had been 357 EU ATC strikes, 254 in France. During the first five months of 2018, 5,000 flights had been cancelled due to ATC strikes.

Spanish ATC staff are currently considering walkouts over working hours, which could affect thousands of peak holiday flights in the coming weeks and months.