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

Air Canada flight attendants returned to the picket line on Sunday defying a government-backed labour board’s order to return to work.The Canadian Union of Public Employees said in a statement that members would remain on strike and invited Air Canada back to the bargaining table.

The decision by the union representing the 10,000 workers means that travel chaos will continue for at least a second day. Air Canada said it had suspended its reopening plan until Monday evening.