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.

Air Canada flight attendants said on Sunday (August 17) they will remain on strike and spurn a government return-to-work order they called unconstitutional that would send them back to their duties.

The Canada Industrial Relations Board ordered airline staff back to work by 2 p.m. Sunday after the government intervened and Air Canada said it planned to resume flights Sunday evening.