Thousands of flight attendants must still approve the agreement. The walkout, which began Saturday, has disrupted half a million travelers’ plans, the airline said.

The union that represents about 10,000 striking Air Canada flight attendants said early Tuesday morning that it had agreed to a tentative contract with the airline, ending a walkout that had disrupted air travel across Canada and stranded thousands of travelers.

The proposed contract, which the Canadian Union of Public Employees said in a statement would bring “transformational change for our industry,” came after the union defied two back-to-work orders and rejected the federal government’s plan to force a deal through binding arbitration rather than negotiation.

“We have reclaimed our voice and our power,” the union said in a statement to its members. “When our rights were taken away, we stood strong, we fought back — and we secured a tentative agreement that our members can vote on.”

The agreement, while a significant step, must still be approved by the flight attendants, who overwhelmingly supported the strike that began on Saturday and risked fines and even jail time by defying the back-to-work order. Air Canada, the nation’s biggest carrier, said before the settlement that the walkout had upended about half a million travelers’ plans, leaving some marooned overseas or in remote parts of Canada.

In a separate note to its members, the union said that the deal was reached at 4:23 a.m. Eastern time after just over nine hours of talks and the assistance of a mediator.

“We must fully cooperate with the resumption of operations,” the message said.

Air Canada said in a statement that some of its 700 daily flights would start flying again on Tuesday evening. Restoring full service, however, will take a week to 10 days, it added.

“The suspension of our service is extremely difficult for our customers,” Michael Rousseau, president and chief executive of Air Canada, said in the statement. “Our priority now is to get them moving as quickly as possible.”

Talks between the sides had resumed on Monday evening. No details of the deal were immediately available, but the union had two major objectives that were at the center of the collapse of negotiations before the walkout.

The union had demanded that Air Canada follow the lead of some U.S. airlines by paying attendants for work that they do before takeoff and after landing, like boarding passengers and carrying out safety checks. Currently, like many airlines, Air Canada pays flight attendants only for work done while the plane’s doors are closed.

“Unpaid work is over,” the union said in the statement, without elaborating further.

Before the strike began, the union had said that Air Canada had accepted the principle of paying for work done on the ground, but was offering only half pay for it. The airline had confirmed that it was willing to pay attendants for ground time, but it did not indicate a rate.

The union also wanted broader wage increases. It said Air Canada was offering to boost wages by 17.2 percent over four years, an amount that the union said would not make up for losses from inflation.

Air Canada did not disclose how much it had offered to raise flight attendants’ hourly pay over the life of any new contract, but it said wages would rise by 8 percent in the first year. Under its offer, the airline said, about 20 percent of flight attendants would make more than 90,000 Canadian dollars, about $65,000, a year. That figure was to include some form of pay for work done on the ground.

On Saturday, less than 12 hours after the strike began, the Canadian government directed the Canada Industrial Relations Board to impose a contract through binding arbitration. Air Canada had sought arbitration twice before the strike began; the union resisted, noting that such settlements rarely address fundamental issues like whether flight attendants should be paid for on-the-ground work.

The union rejected a back-to-work order from the labor board on Sunday, and it remained defiant on Monday after the board ruled the strike illegal, raising the possibility of fines or jail time for the union’s members and leadership.

The union argued that forced arbitration violated its members’ constitutional right to strike, asking the Federal Court of Canada to issue an injunction against the orders while the union challenged them.

The reason Air Canada restarted talks with the union was not immediately clear. But on Monday, Patty Hajdu, the labor minister, said that she had started an investigation into the issue of unpaid work by flight attendants while the plane was on the ground. In an interview with CBC News, she called the issue “deeply disturbing.”