The Canada Industrial Relations Board has ruled that an unusually high volume of sick calls made on Friday by Air Canada pilots amounts to an illegal job action, and has ordered the work stoppage to end.

In a release Friday night, the airline said it was preparing to resume a full flight schedule on Saturday, after roughly 75 flights were cancelled due to the disruptions.

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"The Canada Industrial Relations Board (CIRB) granted, at Air Canada’s request, an order declaring that certain pilots were participating in an illegal strike; ordering ACPA, the pilots' union, to take all reasonable steps to bring to an end the illegal strike; and requiring all pilots participating in the illegal strike to immediately return to work and perform their duties in the normal manner," the release said.

The airline cancelled dozens of flights from major Canadian centres after more than 150 pilots called in sick Friday — about two to three times the normal number, according to Air Canada. Those pilots involved in the work stoppage, a protest against federal back-to-work legislation, could face fines of up to $1,000 a day.

The Canada Industrial Relations Board, an independent quasi-judicial tribunal, has also ordered the Air Canada Pilots Association to pressure pilots to resume normal duties.

Earlier Friday, Air Canada issued a Canada-wide travel alert, warning that "airport disruptions" could affect flights all day and into the weekend.

"It appears a small group of pilots are engaged in an illegal job action," Air Canada spokesman Peter Fitzpatrick said. "There's been a higher than normal level of pilots calling in sick — and as a result we've had to cancel some flights today."

The Air Canada Pilots Association, which represents 3,000 pilots, urged members to report to work and ignore "a small group" of pilots who wanted colleagues to call in sick to show dissatisfaction with management after contract talks broke down.

Capt. Jean-Marc Bélanger, chair of the pilots association's executive council, said the union didn't initiate or sanction the job action.

It was the third time in less than a month that the airline blamed a higher-than-normal number of pilot sick calls for causing flight disruptions.

Air Canada reported back-to-back delays at Pearson on March 17 and 18, a peak travel weekend, due to "operational challenges" that included pilot sick calls, poor visibility and a small fire on the airfield.

Last month, the federal government referred Air Canada's two labour disputes — the other one involved the union representing ground crew — to the Canada Industrial Relations Board, a move that prevents a work stoppage and effectively forced employees back to work.

Fitzpatrick said "the vast majority of pilots" were showing up for work. "There's just a small group today that has decided to engage in this illegal activity."

On an average day, he said, the airline has about 1,500 flights. "So it's confined. But nonetheless, it does cause disruption for our customers and we're working hard to get people to their destination as soon as possible."

Fitzpatrick said the airline has instituted a "flexible" booking policy for Friday and Saturday, allowing customers to change flights to a more convenient time at no extra cost.

At Montreal's Trudeau airport Friday morning, there were a few flight delays and cancellations but no major problems. Halifax airport also reported few issues, with one cancellation reported.

There were some delays in Winnipeg, and two flight delays in Saskatchewan — both in Regina.

Union 'incredibly frustrated'

Bélanger, of the pilots association, said in a note to pilots that the union and its members could face fines for failing to work during the procedures of the Protecting Air Service Act, the federal legislation passed last month that bars Air Canada employees from job action while their contracts are sent to binding arbitration.

Still, he added: "We are not surprised by your strong responses to the corporation's recent correspondence. We are, like you, incredibly frustrated by management's refusal to negotiate with us and by the collusion with the federal government forcing us into a process that we are actively contesting."

Passengers were predictably annoyed at the disruptions.

"We've got hotel reservations and people waiting for us in Vancouver, and it's kind of screwed it all up," Jane Monaghan told CBC News at Toronto airport. She had just arrived at the airport to find her flight cancelled.

Speaking to CBC's Carole MacNeil on Friday, Conservative MP and parliamentary secretary to the minister of transport Pierre Poilievre defended the government's move to pass the back-to-work legislation as necessary "to protect the Canadian economy from the debilitating effects" of an airline shutdown.

"We did exactly the right thing, and to what extent there are disruptions today, those disruptions would have been far worse, far bigger, and far more consequential had we not acted," he reasoned.

'Totally oppressive' legislation

The government's top priority was ensuring that travellers reach their destinations, Poilievre said.

"Certainly, our message to the pilots involved is to get back to work, get the planes in the sky, get passengers where they need to go," he told reporters earlier in the day.

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NDP House Leader Joe Comartin took issue with Poilievre's stance that the government was working to protect customers, describing the move to force pilots back to work as "totally oppressive" and dismissive of labour rights.

"We know exactly where the marching orders come from, and that's from the large multinational corporations," Comartin told Poilievre during a panel on CBC's Power & Politics with Evan Solomon.

The back-to-work legislation "didn't work and it's not going to work," Comartin said. "You're going to continue to have rogue elements."

Liberal industry critic Geoff Regan also weighed in, blaming the Conservatives for intervening in the labour dispute and siding with the company.

Experts in labour relations said the government's actions could be doing more harm than good.

Michael Lynk, a law professor at the University of Western Ontario, mused that the government seems to have "developed close to an addiction" to back-to-work legislation. He said the federal intervention may have poisoned relations between the company and its unions.

"We've had three wildcat strikes at Air Canada over the course of the last four weeks," he said. "That normally wouldn't happen in normal times for industrial relations at a place like Air Canada if it hadn't been for this intervention by the federal government."

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"The fact of the matter is this is a direct result of the way the government has been approaching these labour disputes with a very rightwing approach that says … 'We're going to rig the thing so that arbitration is going to go in favour of management,'" Regan said.

Poilievre shot back that the Liberals and NDP were in a default position to back unions.

In a memo sent to members of the pilots union on Friday, Air Canada Pilots Association president Capt. Paul Strachan said he had forwarded a report to stock analysts expressing extreme concern over corporate management at the airline.

He said the message was for stock analysts, academics and governance advisers. The report states that shareholders should be worried about the airline's continuing "downward spiral" amid rising fuel costs and an economic downturn.

"I am taking the unusual step of alerting fellow shareholders, those who follow Air Canada and those who follow corporate governance issues in Canada, that the corrosive internal environment being created at the airline raises serious questions about its long-term viability," Strachan writes, accusing executives of taking "huge personal financial rewards" while the company's shares hit a 52-week low.

The report says pilot wages at Air Canada are in many cases below those of competitor WestJet, and sometimes even lower than those at charter carriers Air Transat and CanJet. Meanwhile, the airline's top executives have been getting huge raises and are the best paid in the Canadian airline industry, the report says.