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.

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

Air Canada said on Thursday it expects to cancel several dozen flights by day's end and around 500 flights by the end of Friday affecting 100,0000 passengers, ahead of a planned Saturday strike by its unionized flight attendants.