Boeing 737 MAX 8
File photo: A number of grounded Southwest Airlines Boeing 737 MAX 8 aircraft are shown parked at Victorville Airport in Victorville, California, on March 26, 2019. Image Credit: REUTERS

New York

Pilots’ unions at Southwest Airlines Co., United Continental Holdings Inc and American Airlines Group Inc received federal grand jury subpoenas for documents relating to Boeing Co.’s grounded 737 Max.

The Southwest Airlines Pilots Association was given until May 24 to comply with the demand from the US Justice Department’s criminal division, union President Jon Weaks said on Friday. The Air Line Pilots Association, which represents aviators at United and other carriers, said it also received a subpoena. The Allied Pilots Association, whose members work for American, got one as well, said a person familiar with the matter.

Investigators are probing Boeing’s development of the Max, a popular single-aisle model that’s been grounded since mid-March after crashing twice in five months. In both disasters, a new software system known as MCAS repeatedly shoved the nose of the doomed jets down, eventually overwhelming pilots. Congress and the Transportation Department also are examining the Federal Aviation Administration’s approval of the aircraft.

“I don’t know what aspect they are investigating,” Weaks said in an interview. “They just want to know what we have on the Max. We knew it would come eventually.” Max operators

The Southwest pilots’ union will probably seek an extension of the deadline because of the time needed to search through documents, emails and other papers for Max-related items, he said.

Southwest has the largest Max fleet, with 34 planes and additional orders for more than 200. American has 24 of the jets, while United has 14.

At least one former Boeing engineer has also been subpoenaed in connection with the Max, the best-selling plane in the company’s history.

US investigators began a probe weeks after a Lion Air Max 8 plunged into the Java Sea off the coast of Indonesia on Oct. 29. An Ethiopian Airlines jet crashed minutes after take-off from Addis Ababa on March 10, bringing the death toll from the two accidents to 346. The Max, the newest version of the 737, began flying commercially in May 2017.

A law enforcement agent with the Transportation Department Inspector General’s office has contacted at least one FAA official to ask how the MCAS system was certified, Bloomberg reported in March. Another facet of the inquiry has focused on why Boeing didn’t flag the feature in pilot manuals.

A Congressional hearing is set for May 15.