A flight attendant strike at Air France reached its sixth day on Monday, forcing the airline to cancel some 20 percent of its domestic and medium-haul flights from Paris Charles de Gaulle Airport and 5 percent of its international services. The strike, scheduled to last until August 2, has now affected more than 150,000 passengers.

Although Air France expressed confidence it would meet its revised schedule target for August 1, it warned of last-minute cancellations and the possible need to limit the number of passengers on individual flights on which it cannot field a full cabin crew.  

Air France has promised affected customers that it will inform them of any cancellations one day ahead of time and allow those holding a reservation for a flight scheduled for between July 27 and August 2 to postpone their trips until between August 3 and August 12.

Unions representing roughly half of the striking crewmembers called for the weeklong action after they failed to negotiate an extension to the existing contract, which expires in October. Management wants the extension to last 17 months, while unions leaders have asked for between three and five years. At issue remains pay, work rules and promotion policy.

Air France’s last strike lasted from June 11 to June 14, when a pilot walkout cost the airline an estimated €40 million ($44 million).