Air Canada began canceling flights Thursday ahead of a possible strike by its flight attendants that could impact hundreds of thousands of travelers. A complete shutdown of the country's largest airline threatens to impact about 130,000 people a day.

Mark Nasr, Air Canada's chief operations officer, said that cancellations would go from "several dozens" on Thursday, to some 500 by the end of Friday, to the airline being "completely grounded" at the start of the strike on Saturday, in the absence of a resolution.

Canada’s biggest airline is poised to start canceling several dozen flights Thursday ahead of a weekend lockout of flight attendants that threatens to throw travel plans for tens of thousands into chaos during the peak summer season.