The Boeing 737 Max has been on a full-fledged investigation into the US military's five-month-old Boeing 737 Max.

I would like to see if Boeing and the aeronautical authorities had a cohesive relationship during the safety approvals process for the aircraft.

The US Department of Transportation is investigating the Federal Aviation Administration's (FAA) 737 Max approval process and a separate investigation is under way at the Justice Department, the Wall Street Journal reported on Monday.

What is noteworthy is the Ministry of Justice investigation, which is linked to the possibility of criminal punishment.

The Washington DC grand jury reportedly ordered Federal Aviation Administration to file e-mails, messages and communications records between the Federal Aviation Administration and Boeing on the safety approvals of the '737 Max 8'

The Grand Jury's submission order was made under the name of "Justice Department Detention and Prosecution."

Ethiopian Airlines' 737 Max 8 airliner crashed six minutes after takeoff, killing at least 157 people on board, a law enforcement agency said.

"It is extremely unusual for federal prosecutors to investigate civilian airline safety issues," the WSJ said.

The Department of Transportation is also investigating the 737 Max safety certification process against the Federal Aviation Administration.

According to an official, the Department of Transportation survey began in October last year with the crash of an aircraft such as Lion Air Indonesia and focuses on aircraft safety systems related to accidents.

The Department of Transportation's Internal Audit team asked the two departments of the Federal Aviation Administration to keep computer files and to check that the Federal Aviation Administration used appropriate design criteria and technical analysis to authorize an automatic stall prevention system, also known as the Maneuverability Enhancement System (MCAS) Sources said.

The "automatic stall prevention system", which is a device that automatically prevents the gas from diving and diving in turbulence, is considered to be the cause of this tragedy.

Sources say the US Department of Transportation investigation is being conducted by the Federal Aviation Administration for departments that approve the safety of new aircraft and subsequent aircraft, departments responsible for approving compulsory training conditions and training programs.

It is reported that the Federal Aviation Administration did not mandate additional flight simulation training for pilots moving from the old aircraft to the new aircraft.

According to sources, the Federal Aviation Administration is moving to mandate further training on Boeing 's stall prevention system.

The Federal Aviation Administration said the 737 Max was approved in accordance with the Aviation's "Standard Approval Process," including design analysis, ground and flight tests, maintenance conditions, and cooperation with aeronautical authorities.

Boeing has not commented on the survey, but said it had already been approved in line with the agency's requirements.

(yunhap news)