The workers, represented by the Association of Flight Attendants-CWA, twice this year voted down a proposed contract with US Airways, which is in talks with bankrupt American Airlines parent AMR Corp (AAMRQ.PK) about a potential merger.

The union's negotiating committee said it would take its proposal for better economic terms, backed up by the strike vote authorization, to the U.S. National Mediation Board and press for additional mediation sessions in hopes of reaching a joint contract that workers would ratify.

Federal law makes it difficult for airline unions to strike. Mediators would have to declare an impasse and release the parties from talks in order to begin the countdown to a strike.

"Other than understandable frustration on the part of the flight attendant group, there's really no near-term implications" of the strike vote, said Robert Mann, an airline consultant based in Port Washington, N.Y.

The present US Airways, which has about 6,700 flight attendants, was formed from a 2005 merger with America West Airlines. Flight attendants at the combined carrier have been working under separate contracts for years as their union has negotiated to reach a joint agreement.

"We don't want to strike," union leaders who represent the former America West and US Airways flight attendants said in a statement on Tuesday. "Profits are soaring, but flight attendants still shoulder the sacrifices forced through bankruptcy a decade ago as well as disparate, industry-low pay of a first contract from 1999."

In an emailed statement, US Airways said federal mediators have not released the flight attendants union to strike, so there will be no operational disruptions during the holiday travel season.

"The union has told our flight attendants that the strike vote is about positioning at the bargaining table and not about striking, and the union has not requested that the National Mediation Board cease the mediation and negotiations process," the carrier's statement added.

Shares of US Airways rose 3.5 percent to $12.49 on Tuesday.

(Reporting by Karen Jacobs; Editing by Gerald E. McCormick and Jan Paschal)

• A Permanent Economic Emergency