After years of contentious negotiations, Southwest Airlines and its pilots’ union have reached a preliminary labor agreement. The agreement provides for a 14% pay raise for pilots, as well as other compensation and job security provisions. The pact must now be ratified by the union membership before taking effect. If ratified, the new deal would bring the airline’s pilots in line with those at rival airlines, many of whom have already approved more favorable contracts. Southwest is the only major airlines not to have revamped its labor contracts in the past few years. Analysts say the deal is likely to cost Southwest hundreds of millions of dollars and could put additional pressure on the airline’s profits.