Air Canada withdrew its financial targets for the year as a strike by flight attendants entered its third day, forcing the country’s largest airline to cancel about 500,000 flights.

The Canada Industrial Relations Board has declared a strike by 10,000 Air Canada flight attendants illegal and ordered them back on the job after they ignored an earlier order to return to work and submit to arbitration.

The Canada Industrial Relations board ordered the flight attendants union to call off the job action by midday.