TORONTO — Canada’s second largest airline, WestJet, said it canceled 407 flights affecting 49,000 passengers after the maintenance workers union announced it went on strike.

The Aircraft Mechanics Fraternal Association said its members started to strike Friday evening because the airline’s “unwillingness to negotiate with the union” made it inevitable.

The surprise strike affecting international and domestic flights came after the federal government issued a ministerial order for binding arbitration on Thursday. That followed two weeks of turbulent discussions with the union on a new deal.

WestJet said it will continue to park aircraft through Sunday for the long weekend culminating in Canada Day on Monday.

The airline has about 200 aircraft and says they’ll operate approximately 30 by Sunday evening.

The airline’s CEO, Alexis von Hoensbroech, put the blame for the situation squarely on what he said was a “rogue union from the U.S.” that was trying to make inroads in Canada.

Von Hoensbroech said that, as far as the airline was concerned, bargaining with the union had come to an end once the government directed the dispute to binding arbitration.

“This makes a strike totally absurd because the reason you actually do a strike is because you need to exercise pressure on the bargaining table,” he said. “If there is no bargaining table it makes no sense, there shouldn’t be a strike.”

He added the union had rejected a contract offer that would have made the airline’s mechanics the “best-paid in the country.”

In an update to its membership, the union negotiating committee referenced an order by the Canada Industrial Relations Board that does not explicitly bar any strikes or lockouts as the tribunal undertakes arbitration.

Sean McVeigh, a WestJet aircraft maintenance engineer picketing Saturday at Toronto Pearson International Airport Terminal 3, said the strike is an attempt to force the airline to return to a “respectful negotiation.”