Air traffic controllers from the UNSA union have downed tools at airports across France as part of their four-day strike that began on Monday.
But it's not just those airports that are affected with the industrial action, motivated by a dispute over working times and conditions, having a knock-on effect across the country and affecting flights that used French air space.
On Wednesday, it caused the cancellations of at least 43 flights either taking off or landing at Spanish airports, with Barcelona airport being the most affected.
The strike forced the cancellation of 18 flights between France and Spain and 25 other flights between Spanish airports and other European destinations.
Vueling, which has its hub in Barcelona, was the carrier with the most affected flights but Easyjet, Ryanair, Iberia and BA have also reported cancellations.
Passengers due to fly this week are advised to check the status of their flight on the company websites before heading for the airport.