The travel plans of WestJet customers are up in the air after its pilots’ union issued a 72-hour strike notice Monday night. The gambit by the Air Line Pilots Association started a countdown to a flight crew walkout at 3 a.m. on Friday morning, just ahead of the busy May long weekend.

The ALPA said in a news release it plans to begin lawful job action early Friday morning, which the release said “could include grounding all aircraft and effectively shutting down operations.”

The WestJet Group responded with a lockout notice, saying a work stoppage could occur as early as Friday at 3 a.m. MDT.

“Flight disruptions are never an ideal outcome, especially given the tremendous support our guests have shown us, and we want to continue being a major contributor to our company’s success by helping WestJet realize its growth strategy,” Bernard Lewall, who heads the union’s WestJet contingent, said in the news release.

But he added, “However, WestJet pilots will withdraw our services to secure a contract that will fix many of the airline’s labour problems and make it a career destination for pilots once again.”

WestJet Group CEO Alexis von Hoensbroech countered that “The decision to issue a lockout notice, in response to the actions taken by the union today, was not one that was made lightly, and we sincerely regret the inconvenience and uncertainty this continues to cause for our guests,”

The statement noted the lockout notice does not mean a work stoppage will occur, and that both parties remain at the bargaining table. But it said the company would “begin preparations to operate a reduced schedule” and warned it would be “a significant reduction from WestJet and Swoop’s current networks.”

WestJet said guests impacted by flight delays or cancellations will be refunded or re-accommodated as applicable.

WestJet subsidiary Swoop notified customers there is no impact on operations so far, but the head office says it has started preparations to cut the flight schedules of both the flagship and budget carriers.

The union that represents some 1,600 flight crew at WestJet and Swoop had warned Friday that a walkout could come as early as this week as talks dragged on.

Lewall said last week that the workers’ issues revolve around job protection, pay and scheduling, with some 340 pilots leaving the carrier over the past year and a half – mostly to other airlines.

In a statement last week, the Calgary-based airline said its pilots are among the best paid in Canada, but that a contract on par with those recently secured by some US pilot groups would be financially unworkable and put the company’s future at risk.

The union said in its news release it could have filed the strike notice over the weekend, but in a bid to keep the airline operating, it agreed to extend negotiations.

The union noted that while progress was made on most non-cost items, both sides have been unable to reach an agreement.

Karl Moore, an associate professor with the Desautels Faculty of Management at McGill University, says union and management are playing hardball under pressure from inflation, labour shortages and rising US pilot wages on the one hand and a pandemic-battered aviation sector on the other.

Meanwhile, Flair says it is “standing ready” to assist stranded WestJet passengers by adding extra flights between Vancouver, Calgary, and Edmonton starting May 19.