WestJet Airlines Ltd., Canada’s second-largest carrier, will begin canceling flights on Thursday — just ahead of a long holiday weekend — as it prepares for a strike.

Alexis von Hoensbroech, WestJet’s chief executive officer, said on Wednesday that the union is trying to create “maximum damage” by choosing this timing for a work stoppage. The company, controlled by private equity firm Onex Corp., is expecting more than 250,000 passengers during the weekend that includes Canada Day — a national holiday on July 1. 

If a deal isn’t reached, more than 680 workers in the Aircraft Mechanics Fraternal Association can walk off the job as soon as Friday evening.

“We will keep a base network flying, but it will be substantially reduced compared to what we had originally planned,” von Hoensbroech said.

The union threatened strikes earlier this month and in May, but called them off after reaching tentative agreements with WestJet. However, union members rejected those deals. The union said Wednesday that the company has been refusing to engage in meaningful negotiations. 

The airline’s CEO doesn’t expect another deal to be reached before the strike deadline. 

“Right now I don’t see what a resolution could look like unless the union becomes reasonable,” von Hoensbroech said.