Southwest Airlines Boeing 737 MAX aircraft are parked on the tarmac after being grounded, at the Southern California Logistics Airport in Victorville, California on March 28, 2019.Mark Ralston | AFP | Getty ImagesSouthwest Airlines’ pilots filed a suit against Boeing on Monday, saying the aircraft manufacturer misled the airline’s labor union about the plane, which has been grounded for nearly seven months after two fatal crashes.The Southwest Airlines Pilots Association said the planes’ grounding cost its pilots more than $100 million in lost income, which it wants Boeing to pay, because the ban forced the Dallas-based airline to cut back on flights. Southwest operates an all-Boeing 737 fleet and had 34 of the new Max planes in its fleet at the time of the grounding and dozens more on the way. Southwest ordered more 737 Max planes than any other U.S. airline.Global aviation regulators ordered airlines to stop flying the 737 Max after one operated by Ethiopian Airlines crashed on March 10, less than five months after a 737 Max crash in Indonesia. The two crashes killed a total of 346 people.In July, Southwest stripped the 737 Max from its schedules until early January and said it would end service at Newark to free up planes for more profitable routes. The airline said it plans to cut back on flying this year by as much as 2%, down from targeted growth of about 5%.”We believe this lawsuit is meritless and will vigorously defend against it,” Boeing said in a statements “We will continue to work with Southwest Airlines and its pilots on efforts to safely return the Max to service.”The pilots union said it agreed to fly the Max because Boeing said “it was airworthy and essentially the same as the time-tested 737 aircraft that its pilots have flown for years,” the union said in a release. “These representations were false.”The union, which filed its suit in federal court in Dallas, said Boeing’s “errors” cost 346 people their lives, “damaged the critical bond between pilots and passengers, and reduced opportunities for air travel across the United States and around the world.”Boeing is negotiating compensation to airlines over the grounding. Pilots have complained they did not know about a piece of flight-control software that was implicated by investigators in both 737 Max crashes until after the first plane, Lion Air Flight 610, went down on Oct. 29, 2018, killing all 189 aboard.Boeing is now preparing a software fix for the planes that the Federal Aviation Administration will have to review, along with updated pilot training materials. The Chicago-based company says it expects the planes to be recertified in the fourth quarter.