WestJet airplane mechanics hit the picket lines Friday evening in a surprise move that threatened to disrupt flights for thousands of travellers at the outset of the Canada Day long weekend.

Canadians can expect “severe travel disruption” if the strike by the Aircraft Mechanics Fraternal Association (AMFA) is not called off, WestJet said in a release.

The abrupt job action by the Aircraft Mechanics Fraternal Association (AMFA) comes one day after WestJet expressed relief they had averted a work stoppage thanks to a ministerial order for binding arbitration on Thursday and following two weeks of turbulent wrangling with the union.

The country’s second-largest airline has again asked for immediate intervention by the federal labour minister and the Canada Industrial Relations Board.

“We are extremely outraged at these actions and will hold AMFA 100 per cent accountable for the unnecessary stress and costs incurred as a result,”  said WestJet Airlines president Diederik Pen in a release.

The union said in a statement its 680-odd WestJet workers walked off the job at 5:30 p.m. MDT, arguing that the carrier’s “unwillingness to negotiate with the union made the strike inevitable.”

However, WestJet said that because a future collective agreement is now in the hands of the country’s labour tribunal, a strike gives the union no leverage and amounts to “pure retaliation.”

Earlier this month, the mechanics voted overwhelmingly to reject a tentative deal with the Calgary-based airline, prompting WestJet to seek government intervention and resulting in two 72-hour strike notices issued by the union — the first was rescinded last week.

With the clock ticking down toward a Friday deadline, Labour Minister Seamus O’Regan on Thursday directed the airline and the union into binding arbitration, seemingly steering clear of a work stoppage that would have upended plans for up to 250,000 passengers during one of the busiest travel weekends of the year.

On Thursday night, WestJet and the union both said they would follow the order, with a strike apparently off the table.

“AMFA has confirmed they will abide by the direction. Given this, a strike or lockout will not occur, and the airline will no longer proceed in cancelling flights,” WestJet said Thursday.

The reversal on Friday night therefore came as an even bigger shock to executives and travellers alike.

“Is my flight on Sunday in jeopardy?” asked Andrew Wheatley of Edmonton in a social media post.

“I support a union’s right to strike if it’s legal. And hopefully they will get a good deal. But at the same time, I have to be at work Monday morning,” he added in a message.

No further flights were cancelled Friday night, WestJet spokeswoman Morgan Bell clarified in an email. But as of midnight, weekend trips hung in limbo, as mechanics are needed to inspect and repair planes daily.

Bell said there is “no risk to the safety of our operation.”

In an update to members, the union negotiating committee cited constitutional protections around collective action.

It also pointed to an order by the industrial relations board that does not explicitly bar strikes and lockouts as the tribunal undertakes arbitration following O’Regan’s directive.

“The board finds that the ministerial referral does not have the effect of suspending the right to strike or lockout,” the tribunal wrote Thursday.

The union committee insisted that the labour minister had been “silent on the issue.”

“Having had no indication that the board would revoke AMFA’s strike notice, AMFA directed its members to cease all work,” it said.

Tensions between the two sides had already frayed almost to the breaking point over the past month.

The strike notices forced WestJet to cancel roughly 70 flights since June 20, affecting roughly 10,000 passengers and potentially costing the company millions of dollars. The carrier’s decision to start concentrating its 180-plane fleet sought to avoid leaving aircraft in far-flung locations and stranding passengers and crew in the event of a work stoppage.

As negotiations around the contract dragged on in a windowless conference room at a hotel near Toronto’s Pearson airport this week, the tone of statements put out by the two sides grew chippier.

The union’s bargaining demands showed a failure to act in good faith and its public statements included “inflammatory” and “offensive” elements, claimed an affidavit from one lawyer representing WestJet.

In a letter to a WestJet senior manager on Friday, union national president Bret Oestreich claimed that the airline “engaged in related unlawful conduct” by shutting down further negotiations.

Just over a year ago, the airline found itself in similar circumstances after some 1,800 pilots threatened to walk off the job.

WestJet averted a strike after reaching a last-minute deal in the wee hours ahead of a long weekend in May, but not before cancelling more than 230 flights and disrupting the travel plans of thousands of passengers.

This report by The Canadian Press was first published June 28, 2024.

Christopher Reynolds, The Canadian Press