‘Striking is right’
The union is protesting against “chronic understaffing”, the planned introduction of a clock-in system, outdated equipment and “toxic management practices that are incompatible with the requirements of calm and safety”.
It was joined by the third largest union, USAC-CGT.
The main air traffic controllers’ union, SNCTA, had no plans to join them.
Airports in the south were particularly hard hit, with 30 percent of flights cancelled in cities including Lyon and Marseille.
Air France said it had been “forced to adapt its flight schedule” without specifying the number of cancellations, but stressed that its long-haul network was not affected.
On Friday, the situation is expected to become even more tense at Paris airports and Beauvais, where the DGAC has ordered a 40-percent reduction in the number of flights.
Business aviation, particularly in Nice and Le Bourget near Paris, has also been significantly affected, sources said.
Some passengers tried to take the disruptions on the chin.
“Striking is a right,” said Carol Jelic, a 66-year-old Canadian travelling to Stuttgart. “We can’t lose that right. But it does inconvenience,” she told AFP at Paris CDG airport.
Eric Nouen, a 60-year-old travelling to Montpellier from French Guiana, a region of France in South America, said he was not going to complain.
“Right now, everyone could go on strike. Everyone has a reason right now.”