Air Canada flight attendants voted Tuesday in favour of going on strike as early as Sept. 21.

Almost 5,200 ballots, representing 98 per cent of the votes cast, supported a walkout. The turnout was 78 per cent. Voting was conducted over 10 days and ended Tuesday.

"A strike vote does not mean we will necessarily go on strike, but it means we will strike if we need to. What we want and still hope for is a negotiated deal with the company," the president of the flight attendants' union, Jeff Taylor, said in a statement.

"No one wants a strike, but if we can't reach a tentative agreement which addresses our members concerns, and soon, it could be our only choice," he said.

If a deal isn't reached, 6,800 flight attendants could walk off the job in the airline's second strike in three months.

About 3,800 customer sales and service representatives represented by the Canadian Auto Workers union held a three-day strike in June.

Taylor has said members are unhappy after more than a decade of concessions and sacrifices to make Air Canada financially viable.

Earlier deal rejected

The flight attendants, represented by the Canadian Union of Public Employees, massively rejected an earlier tentative deal late last month.

Air Canada declined to comment about its contingency plans, but reports have suggested it has trained managers as replacements.

Analysts believe a strike would affect operations immediately and likely prompt the federal government to either block a strike or end one quickly.

"I think it would be a much more challenging situation than it was with the customer service agents because part of the flight attendant's role is the safe operation of the aircraft," Chris Murray of PI Financial, said in an interview.

"You may be able to operate some of the fleet, but not all of it."

The union has urged the government not to intervene in a strike.

But federal Labour Minister Lisa Raitt tabled back-to-work legislation two days into the CAW strike saying the government wouldn't tolerate any disruption to the public or impact on the economy.

The two sides hammered out a deal before the legislation was passed, but sent the contentious issue of requiring new hires to join a defined contribution pension plan — instead of the more expensive defined benefit system — to an arbitrator.

Murray suspects any strike now would be short-lived, if it gets that far.

"I think they still have some time to go back to the table and come to a tentative agreement."

Air Canada has had trouble concluding collective agreements that are ratified by workers. Pilots, flight attendants and flight dispatchers all rejected tentative agreements recommended by union bargaining committees.

That highlights the challenges Air Canada faced in negotiating a deal that can win employee support.

Under the worst-case scenario, the government could send the dispute to binding arbitration.

Canada's largest airline and its regional partners carry about 31 million passengers annually to more than 170 destinations on five continents.

With files from The Canadian Press