About a dozen pilots called in sick to protest Air Canada’s bitter contract feud, forcing the carrier to cancel at least 19 flights, CTV News reported.

The apparent protest comes as Canadians begin returning from March break holiday, one of the busiest travel days all year.

On its website, Air Canada said it expected delays between Montreal and several Canadian and American destinations.

“Pilots, for public safety reasons, can call in sick if they feel they’re fatigued or tired,” CTV’s Ottawa bureau chief Robert Fife said. “But they obviously can’t call in if they’re using it as part of a labor dispute or a work stoppage.”

Most of the cancellations or delays happened in Montreal, CTV said, with pilots saying they’re stressed or fatigued.

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Air Canada admitted to delays, but said they’re part of normal airline operations due to weather and volume, Postmedia News said.

“All we can say is that on this peak travel weekend, we face a number of operational challenges, including weather,” Air Canada representative Peter Fitzpatrick wrote in an emailed statement. “However, the vast majority of Air Canada employees are working hard to get our customers to their destinations safely.”

Fog was also an issue in the Montreal area earlier today, Postmedia reported.

However, earlier this week, the airline said it expected the Air Canada Pilots Association to “engage in illegal job action in the form of … increased sick calls,” CBC News said.

The Canadian Conservative government recently passed legislation that forced the airline and its 3,000 pilots and 8,600 ground crews into mediation for their ongoing labor dispute.

It’s the second time this year that Labour Minister Lisa Raitt has taken the extraordinary measure by intervening with a private company. Earlier this year, she legislated Air Canada's flight attendants back to work.

She said an Air Canada stoppage could cost the Canadian economy more than $22 million per week.

“These issues fall with Air Canada internally, and should Air Canada feel that these actions constitute an illegal strike, they can bring this matter to the Canadian Industrial Resolution Board,” a statement from Raitt’s office said, according to CBC.

Even the airline’s chief pilot said he wasn’t coming into work on what’s expected to be one of the busiest flying days this year.

Jean-Marc Belanger, chairman of the pilots’ association executive council, sent an email to his fellow pilots saying he “self-assessed as unfit to fly,” CBC said.

He said sleep deprivation and “the unknown commitment of the corporation to support me in line with the many aspects of our joint obligations” contributed to his decision.

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