Air Canada said it’s delaying the resumption of flights by a day after a flight attendants’ union defied an order to end its strike by the afternoon of August 17, escalating a labor crisis and prolonging mass travel disruption.

About 240 flights scheduled starting on the afternoon of August 17 were canceled, and service will now restart on the evening of August 18, the airline said in a statement. The Canadian Union of Public Employees “illegally directed its flight attendant members” to ignore a labor relations board’s order to return to work, according to Air Canada. 

The union, which represents more than 10,000 Air Canada flight attendants, said it’s challenging the order and called it “blatantly unconstitutional.” 

Air Canada flight attendants and supporters during a strike at Toronto Pearson International Airport in Mississauga, Ontario. Photo: Bloomberg

Canada’s biggest airline had said earlier on August 17 that flights would resume in the evening and gradually return to full capacity, in response to the Canada Industrial Relations Board’s order.

Patty Hajdu, Canada’s minister of jobs and families, directed the board on August 16 to order the parties to resume operations. She requested the CIRB impose binding arbitration just hours into the strike, which grounded hundreds of flights by the Montreal-based airline after talks over pay fell through. 

The walkout would disrupt some 130,000 passengers a day during the summer holiday season, the airline previously said.