Air Canada Chief Executive Mike Rousseau said on Monday that the airline was "amazed" by the decision of its flight attendants' union to defy the Canada Industrial Relations Board, which has declared the union's strike unlawful.

Air Canada has suspended plans to restart operations after the union representing 10,000 flight attendants decided to defy a return-to-work order

The Canadian carrier said it expects to call off 500 flights by the end of Friday. Air Canada said it was suspending its schedule and trying to get passengers booked with other airlines to limit disruptions.

Air Canada on Monday withdrew its third quarter and full-year earnings guidance due to a disruption in operations after its flight attendants went on strike.

Air Canada wants to reinforce the gender wage gap by forcing Air Canada flight attendants – 70% of whom identify as women – to accept a wage offer less than one-third what Air Canada offered its pilots less than a year ago.