Southwest Airlines Co. flight attendants overwhelmingly rejected a six-year tentative contract their union said would have made them the highest paid in the U.S. industry.

About 87 percent of attendants participating voted against the agreement, according to the Transport Workers Union, which represents about 13,000 Southwest employees. Southwest’s flight attendants last rejected a tentative agreement in 1996.

The proposed contract would have provided 3 percent raises in 2015, 2017 and 2019, alternating with 3 percent bonuses in 2016 and 2018, the TWU said. The Dallas-based airline remains in contract talks with unions for pilots, mechanics, airport ramp workers and two smaller labor groups.

Southwest has sought to minimize labor cost increases by securing improved efficiency and productivity in exchange for raises and other benefits, and won extended workdays for attendants in the proposed accord. Labor was the airline’s largest expense last year, accounting for 33 percent of total operating costs.

This article was written by Mary Schlangenstein from Bloomberg and was legally licensed through the NewsCred publisher network.

Photo Credit: Flight attendants and other Southwest employees during the airline's new branding launch. Southwest Airlines