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.

The dominant air carrier in Canada set in motion a process that could ground 130,000 passengers a day by Saturday.

About 500 flights would be grounded by midnight Friday, and it would take about a week to restore full operations once a labor agreement is reached, the company said.