Air Canada and its 6,800 unionized flight attendants have reached a tentative deal on a new collective agreement — just hours before a 12:01 a.m. ET strike deadline.

The news of the deal came late Tuesday afternoon, after Air Canada said it had made temporary modifications to some regularly scheduled Air Canada Express flights operated by Jazz for Sept. 21.

The airline has said that affected customers will be notified by the company or their travel agents and that those who booked directly through Air Canada will receive an email or SMS notification if a change has been made to their itinerary. Air Canada Express flights operated by Jazz will return to a regular schedule on Thursday, the airline said.

"It's business as usual and customers can continue to make their travel plans on Air Canada with confidence," Susan Welscheid, the airline's senior vice-president of customer service, said late Tuesday afternoon.

CUPE union president Jeff Taylor said the union's executive is recommending that its members approve the deal.

Details of the deal won't be made public until after the vote is held to ratify it, which will be in 17 days.

Union meetings will be held in Vancouver, Calgary, Toronto and Montreal.

"There's a lot of good things but like I said I can't give you any details because our members need to get the details first ," Taylor told reporters.

He said there would be no job reductions.

Key issues in the negotiations included wages, pensions, crew rest, working conditions and work rules.

In August, the flight attendants resoundingly rejected a tentative deal negotiated with the airline, forcing the two sides back to the drawing board. But Taylor said he's pretty confident his union members will support this deal.

"It's everything that pretty much they were asking us to bring to them," he said.

The new agreement came after the federal government indicated it was prepared to quickly bring in back-to-work legislation to end any labour disruption at Air Canada.

The government said it would have used the legislation to avoid the economic impact of a work stoppage.

But CUPE president Paul Moist said the agreement was actually delayed by the actions of Labour Minister Lisa Raitt.

"We achieved an agreement with Air Canada in spite of the efforts of the government of Canada," Moist told CBC-TV's Power & Politics with Evan Solomon.

He said the two sides were close to a deal Monday night but representatives of the airline and the union were summoned to a meeting with Raitt.

"Air Canada didn't want to go. The mediator didn't want to stop bargaining and I refused to let our negotiators leave Montreal. We attended the session with her and I prevailed upon her, 'We're that close to a collective agreement, you needn't take action which I think you are contemplating.' And 30 minutes after that meeting, she walked into the Parliament and served notice of legislation," Moist said.

But Raitt defended her government's threat to use back-to-work legislation, saying that while a deal was close, nothing had been committed to, except a notice to strike.

"What I also knew and what we know as a government is that on Wednesday morning that there could be a work stoppage," Raitt said on Power & Politics. "We know how long it can take for legislation to go through the House, what the economic effect of work stoppage would have."

When the airline's customer service agents walked out in June, Raitt introduced back-to-work legislation.

As it happened, the two sides reached a deal three days before Ottawa could pass the measure into law.

With files from The Canadian Press