Almost two dozen flights to and from Ireland to Spain and France have been cancelled because of a strike by French air traffic controllers.
The 36-hour industrial action which began yesterday evening will continue until tomorrow morning.
The French Civil Aviation Authority has said flight delays and last-minute cancellations cannot be ruled out.
Intending passengers are being asked to check their airline websites for updates.
Twenty-three Ryanair and Aer Lingus flights to and from France and Spain have been cancelled today.
Ryanair has said that so far this year, strikes staged by air traffic controllers in France have led to the cancellation of 4,000 flights.
Last week, the airline handed in a petition with over a million signatures to the European Commission, demanding that it take action to protect overflights across the union during air traffic control strikes to keep skies open.