Mechanics at Canada's second-largest airline WestJet went on a surprise strike late Friday, threatening to ground planes and disrupt travel at the start of a national holiday long weekend.
The airline's president, Diederik Pen, said in a statement the walkout could cause "severe disruptions" for thousands of travelers.
It comes one day after a ministerial order for binding arbitration to settle a contract dispute was believed to have averted labor unrest at the airline.
The strike action against the company started at 7:30 pm in eastern Canada (2330 GMT), when the airline mechanics' union said "the airline's unwillingness to negotiate with the union made the strike inevitable."
A strike notice was issued earlier this month after the mechanics rejected a tentative deal with the Calgary-based airline.
"We are extremely outraged at these actions," Pen said, adding the strike would cause "unnecessary stress and costs" while having no impact on the arbitration outcome.
The company, he said, has asked the federal labor minister, Seamus O'Regan, and Canada's labor relations board to step in to end the strike.
WestJet flies 198 commercial aircraft to more than 100 destinations in nearly 30 countries.