Airlines canceled scores of flights in and out of France on Wednesday because of a two-day stoppage by air traffic controllers upset over work conditions and plans to raise their retirement age to 59 from 57.
The French civil aviation authority (DGAC) said as many as one in two flights would be scrapped on Thursday, the second day of the strike.
Budget airline easyJet said it was cancelling 118 flights to and from France on April 8 and apologized to passengers for a strike "outside of our control".
Low-cost carrier Ryanair posted dozens of flight cancellations on its website, not just in France but across Europe, blaming the French strike.
The state-employed air traffic controllers are threatening further two-day stoppages later in April and at the start of May -- when school breaks and public holidays boost vacation traffic -- over what they say is management refusal to take their demands seriously.
In a blog post, the SNCTA trade union denounced plans to raised the age at which controllers are entitled to retire and highlighted other complaints, including declining staff numbers at a time of increasing national and European regulation.
Air France had advised passengers on Tuesday that 40 percent of medium-haul flights would be canceled, with as many as two thirds of short-haul flights scrapped at Paris Orly and other French airports.