Southwest Airlines reached a tentative agreement with flight attendants on a four-year contract through May 31, 2012, the Dallas-based carrier said on Thursday.

Earlier in the day, the board of Transport Workers Union Local 556 voted for the tentative pact to be presented to the flight attendants for a vote, Southwest said. Members will have a chance to vote on ratification over the next few weeks, said Southwest, the largest U.S.-based low-cost carrier.

Negotiations with TWU Local 556, which represents 9,800 flight attendants, began in May, Southwest said.

Rank-and-file voting will open on May 4 and will close on May 18, with results posted shortly after, said TWU Local 556 president Thom McDaniel.

The agreement solves a lot of problems for the company and our members, he said.

TWU Local 556 is separate from TWU Local 555, which represents 7,200 other workers at the carrier.

In November, talks with TWU Local 555 were stalled as the union and the company could not agree on wages. The unit and Southwest filed for federal mediation on October 31.

A spokesman for Southwest said TWU Local 555 tentatively agreed to a contract a couple of months ago and was set to vote on it very soon.

Southwest shares were up 5 percent at $6.45 in afternoon trade on the New York Stock Exchange.

(Reporting by Deepa Seetharaman, editing by Dave Zimmerman and John Wallace)