Air Canada has started canceling flights ahead of a planned lockout of its 10,000 flight attendants, scheduled to begin on Saturday, following a strike notice from the Canadian Union of Public Employees.

The airline responded with a lockout notice, initiating a phased suspension of operations expected to ground more than 500 flights by Friday.

The carrier transports approximately 130,000 passengers daily, including around 25,000 Canadians returning from abroad.

Operations by regional partners, such as Jazz and PAL Airlines, will continue unaffected.

Air Canada has stated that a full halt in operations could require up to a week to restart, even if a settlement is reached promptly.

Negotiations between the airline and the union have been ongoing for eight months without agreement.

Air Canada’s latest offer included a 38 percent pay increase over four years, which the union rejected, citing that it remained below market standards.

The union also maintains that flight attendants are not compensated for duties performed before and after flights.

In a recent vote, 99.7 percent of members supported strike action.

The airline has committed to offering full refunds or fee-free rebooking to passengers whose flights are canceled, but has warned that finding alternative travel may be difficult during the peak summer travel period.