A bitter contract fight between Canada’s largest airline and the union representing 10,000 of its flight attendants escalated Friday as the union turned down the airline’s request to enter into government-directed arbitration,

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

Canadian Labor Minister Patty Hajdu said on Friday that she met jointly with Air Canada and the Canadian Union of Public Employees (CUPE), urging both sides to work harder and remain at the negotiating table to reach a deal and avert a potential strike.