Air Canada began grounding flights on Thursday in advance of a potential strike by its 10,000 flight attendants this weekend.

While the immediate effect of the cancellations was limited, a complete shutdown of the airline would bring travel chaos to a country where vast distances leave few practical alternatives to flying. It would also disrupt a sizable chunk of international travel to or from the country.

Mark Nasr, the company’s chief operations officer, told reporters on Thursday that “several dozen” flights to overseas destinations scheduled for that evening had been canceled. The cancellations will be scaled up leading to a total shutdown of flights operated directly by the company by early Saturday morning, which would ground about 130,000 travelers a day.

“The impact that this is going to have on our customers is profound,” Mr. Nasr said at a news conference in Montreal. “It’s simply not the kind of system that we can start or stop at the push of a button. So in order to have a safe and orderly wind down, we need to begin now.”

Both Air Canada and the flight attendants’ union have filed notices setting up the shutdown for just after midnight on Saturday morning: The union’s notice said that it intended to strike, and the company’s that it would lock out employees. Those steps followed apparently acrimonious negotiations that Air Canada unsuccessfully tried to resolve through government arbitration. The flight attendants are seeking improved wages and compensation for work they do before flights take off and after they land.

Air Canada is the dominant carrier in Canada and offers about 48 percent of available seat miles, the industry standard for measuring capacity, on domestic routes, according to Cirium, an aviation data firm. Unlike its three major Canadian competitors, Air Canada has a wide network of international flights that reaches 65 countries.

Any shutdown would come in the midst of a revival of domestic vacation travel, as many Canadians boycott the United States after President Trump’s unilateral tariffs on Canadian goods and repeated calls for annexing the country.

Canada’s census agency reported this week that the number of Canadians returning from the United States by air fell by 25.8 percent in July. The month also reversed recent historical patterns — more Americans traveled to Canada than Canadians visited their neighbor.

While Air Canada said that it would try to rebook passengers on other airlines, Mr. Nasr acknowledged that it would be difficult.

“Of course, and unfortunately, because this is the peak of the summer travel season there are very few seats available out there,” he said.

If a strike does come to pass, it will not affect regional flights generally offered on small propeller planes that are operated by two small carriers under contract to Air Canada, the company said. They account for about 300 of the airline’s 1,000 daily flights.

The talks appear to have broken down over the two compensation issues.

Like most North American airlines, Air Canada pays its flight attendants only for the hours they are in the air. In 2022, Delta Air Lines became the first major U.S. carrier to pay for work performed during boarding. American Airlines reached a deal with the union that represents its flight attendants last year to do the same, and Alaska Airlines followed suit this year. Flight attendants for United Airlines are currently seeking similar compensation in talks with the carrier.

There is a “very clear path for Air Canada to avoid job action: Pay your workers when they’re on the clock, and pay them a wage that allows them to live and work in dignity,” Wesley Lesosky, president of the branch of the union that represents Air Canada flight attendants, said in a statement on Thursday.

But at the news conference on Thursday, Arielle Meloul-Wechsler, Air Canada’s executive vice president for human resources, said that a ground pay proposal had been “in our offers for months.” She did not provide any details.

The union said in a statement that Air Canada was offering to increase its members’ wages by 17.2 percent over four years, which the union contends would not make up for losses from inflation.

Ms. Meloul-Wechsler said on Thursday that the company was offering a 38 percent increase in total compensation, which includes wages and benefits, over the same period. Before she could be asked what portion of that is wages, Air Canada shut down the news conference. Four people, most of them in flight attendant clothing, walked in front of the podium with union signs condemning the company’s offer. Air Canada later declined to break out the wage portion of its offer.

If a strike goes ahead, a recent Supreme Court ruling will make it difficult for the federal government to order an end to the action. The union contends that Air Canada is pushing for arbitration because contracts reached through that route rarely include new measures — like payment for work performed before takeoff and after landing.