Air Canada has canceled hundreds of flights — many of them international flights — as a potential strike by flight attendants looms.

Their union says one of its core demands, to receive pay for groundwork, is unlikely to be introduced in arbitration. The airline began canceling flights ahead of the potential strike.

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.