NEW YORK (CNN/Money) - Pilots at United Parcel Service have authorized a strike, ahead of mediated talks set for the next two weeks.

The Independent Pilots Association, which represents the freight carrier's 2,500 pilots, said the vote was more than 99 percent in favor of authorizing its five-member executive board to call a strike. The union and the company started negotiating on a new contract in October 2002. Federal mediators have scheduled two weeks of talks starting May 16.

"UPS (Research) knows what it's going to take to make a deal, and their actions at the table over the next two weeks will let us, and the (mediators), know if they want to come to agreement or dig-in for the traditional UPS labor fight, which will further confuse our customers and leave them uncertain about the stability of the airline," said a statement from union president Tom Nicholson. The union has never struck the airline itself, although it honored a 1997 strike by Teamsters.

UPS spokesman Mark Giuffre said the company won't comment on details of its offers.

"We've said pilots would receive pay increases but it would have to be something reasonable and allows the company to offer competitive services," he said. "I can't think of any other pilots' group that is being offered pay increases in the current environment."

The union said a survey of major shippers show 47 percent anticipate a UPS pilot contract only after public controversy and some work stoppage, and that 24 percent of those businesses are making contingency plans in case of a work stoppage.

UPS is the world's largest transportation company, and it has a fleet of 268 heavy jets making close to 2,000 flights a day.

While most of UPS's employees, including its Teamster-represented drivers, are covered by the National Labor Relations act, which allows unions relative freedom to strike, the pilots operate under the Railway Labor Act, which imposes restrictions on unions going on strike or management lock-out of employees.

Mediators would have to call for a 30-day cooling off period before the pilots could strike, and the President has the power to order the workers to stay on the job while a board he appoints proposes a contract to the two sides.

"There's a long process before we even get to potential for work stoppage," said Giuffre. "This vote really means nothing. There's no surprise in the unity among the pilots."

Shares of UPS were little changed in early trading Thursday following the release of strike vote results.

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