The union representing pilots for the biggest U.S. customer of Boeing's 737 Max jets sued the company Monday, accusing it of lying when it said the troubled planes were just as safe as their predecessors.
Two Max 737s have crashed in the last year, killing 346 people. After the second crash, in March, aviation authorities and airlines around the world grounded the 737 Max series, taking 387 aircraft out of the skies for almost 60 airlines.
In a lawsuit filed Monday in Dallas County, Texas, District Court, the Southwest Airlines Pilots Association, or SWAPA, said its members signed off on flying the newer planes because Boeing Co. told them that they were airworthy and "essentially the same as the time-tested 737 aircraft that its pilots have flown for years."
"These representations were false," the union said.
Download the NBC News app for breaking news
As a result of the grounding, Southwest — the biggest customer for the 737 Max series — has had to cancel more than 30,000 scheduled flights, costing its pilots more than $100 million in pay, the suit claims.
"We have to be able to trust Boeing to truthfully disclose the information we need to safely operate our aircraft," Jon Weaks, the union's president, said in a statement.
"In the case of the 737 Max, that absolutely did not happen," Weaks said. "Our pilots should not be expected to take a significant and ever-expanding financial loss as a result of Boeing's negligence."
Boeing responded in a statement that said that it valued its relationship with SWAPA but that "we believe this lawsuit is meritless and will vigorously defend against it."
"We will continue to work with Southwest Airlines and its pilots on efforts to safely return the Max to service," Boeing said.
The suit was filed in Dallas County because Southwest is based in Dallas, and "a substantial part of the events and omissions giving rise to the claims asserted herein took place within Dallas County," according to the suit, which seeks unspecified damages, compensation for lost pay and the union's expenses in cooperating with federal investigations, and interest.
Almost 190 people were killed when Lion Air Flight 189 crashed into the Java Sea 13 minutes after takeoff from Soekarno–Hatta International Airport in Jakarta, Indonesia, on Oct. 29, 2018. Almost 160 people were killed March 10 when Ethiopian Airlines Flight 302 crashed six minutes after takeoff from Addis Ababa Bole International Airport in Ethiopia.
Preliminary investigations indicated that an automated system erroneously engaged on both planes, forcing the planes' noses to point down and leaving pilots unable to regain control.
The National Transportation Safety Board said in a report last month that the responses of the pilots on both planes "differed and did not match the assumptions of pilot responses" that Boeing and the Federal Aviation Administration had used in assessing the 737 Max's safety.
"We saw in these two accidents that the crews did not react in the ways Boeing and the FAA assumed they would,” NTSB Chairman Robert Sumwalt said in a statement accompanying the report.
Sumwalt stressed that it hadn't been determined that that was the fault of the pilots, who he said "were faced with multiple alarms and alerts at the same time."