French travellers were facing a weekend of travel disruption, as pilots at Air France announced Friday they were extending their strike, their longest since 1998.
The company said it will have to scrap 55 percent of its flights on Saturday, when pilots' unions will also announce whether the strike will continue into a second week.
Pilots have downed tools in protest at the airline's plans to develop its low-cost subsidiary Transavia France, whose pilots cost considerably less to employ.
Air France pilots, who can earn as much as 250,000 euros ($321,000) per year, are worried that management will seek to replace them with cheaper labour from Transavia France.
Management has made concessions to end the strike -- notably limiting the Transavia France fleet -- but unions have rejected all offers so far.
The pilots have also been unmoved by the appeals of senior politicians including Prime Minister Manuel Valls to return to the cockpit.
"It is regrettable that a single category of employee, in this case pilots, can bring air transport in the country to a standstill," Valls said on Wednesday.
He said the strike was "incomprehensible" to most French people and was "weighing heavily on Air France, on its finances but also on the attractiveness and the image of our country."
Air France boss Frederic Gagey has put the daily losses from the strike at 10 to 15 million euros.
The chief executive of the wider Air France-KLM group, Alexandre de Juniac, said: "I'm wondering if there is really a desire to negotiate" on the part of the unions.
Unions want to ensure Air France pilots are at the controls of any plane with more than 100 seats, regardless of the operating company -- Transavia included -- a demand management has so far rejected.
As in previous days, airports were largely deserted as Air France notified passengers in advance that their flights were cancelled.