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. The union representing around 10,000 Air Canada flight attendants issued a 72-hour strike notice Wednesday.

Air Canada has canceled most of its flights over the next few days to prepare for a strike by flight attendants. Some travelers may end up stranded as a result.