Air Canada expects to cancel the majority of its estimated 700 daily flights on Friday, ahead of a planned Saturday strike by unionized flight attendants, leaving some 100,000 passengers scrambling to make alternative travel plans.

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.

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.