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.

The union representing 10,000 flight attendants for Canada's largest airline issued a 72-hour strike notice on Wednesday.

Air Canada has started canceling flights ahead of a possible work stoppage by flight attendants that could impact hundreds of thousands of travelers.