Air Canada said it suspended plans to restart operations on Sunday after the union representing 10,000 flight attendants said it will defy a return to work order.

After months of stalled negotiations, 10,000 Air Canada flight attendants walked off the job early Saturday morning. The federal government stepped in hours later to order binding arbitration, forcing an end to the strike — or so they thought.

As Air Canada cancels flights in anticipation of a possible strike, experts say this could result in millions of dollars of delayed claims.