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.

Air Canada began cancelling flights on Thursday after receiving a strike notice from the flight attendants' union, warning all operations could be shut down by Saturday. Chief operating officer Mark Nasr told reporters Thursday that the airline had begun "a gradual suspension of Air Canada and Air Canada Rouge operations.

Air Canada started canceling flights on Thursday ahead of a possible work stoppage by flight attendants that could impact hundreds of thousands of travelers. A complete shutdown of the country's largest airline threatens to impact about 130,