WASHINGTON (BLOOMBERG) - A former Boeing pilot was charged with deceiving United States aviation regulators in the first prosecution related to two fatal 737 Max accidents that plunged the aviation titan into crisis.

Mark Forkner, a former chief technical pilot for the company, was indicted on Thursday (Oct 14) on charges that he deceived the Federal Aviation Administration's (FAA) Aircraft Evaluation Group during the agency's evaluation and certification of the Max, the Justice Department said in a statement.

He is accused of providing the FAA with false, inaccurate and incomplete information about a new part of the flight controls for the Max.

Because of his alleged actions, airplane manuals and pilot-training materials for US airlines did not have any reference to the Manoeuvring Characteristics Augmentation System, or MCAS, the software system that was later linked to both tragedies.

"In an attempt to save Boeing money, Forkner allegedly withheld critical information from regulators," Mr Chad E. Meacham, the acting US attorney in Dallas, said in a statement.

"His callous choice to mislead the FAA hampered the agency's ability to protect the flying public and left pilots in the lurch, lacking information about certain 737 Max flight controls."

The FAA and Boeing declined to comment. Attorneys for Forkner could not immediately be reached for comment.

The case is the culmination of a criminal investigation that began in late 2018 after the first of two crashes that combined killed 346 people and spurred the longest grounding of a commercial jetliner in US aviation history.

The revelations from accident reports have badly dented Boeing's reputation and raised questions about how a potentially aggressive new feature was overlooked by regulators and omitted from pilot manuals.

As chief technical pilot for Boeing, Forkner oversaw the drafting of pilot training materials before the Max jetliner was certified by US regulators in 2017.

The Chicago-based planemaker entered into a US$2.5 billion (S$3.4 billion) agreement earlier this year to settle a criminal charge that it misled the FAA.

Forkner's actions figured prominently in the deferred-prosecution agreement, which was struck in the waning days of the Trump administration.

The Justice Department agreed to dismiss the criminal charge against Boeing if the company cooperated by making current and former employees available to testify.

As a mid-level manager at Boeing, Forkner complained in colourful and sometimes crass messages about the MCAS. The missives sparked outrage at the FAA and on Capitol Hill when they were made public in late 2019 and early last year.

Forkner bragged of using "Jedi mind tricks" on regulators and complained that the Max was "designed by clowns, who in turn are supervised by monkeys".

One of Boeing's big selling points with customers like Southwest Airlines had been that pilots certified for the previous generation of 737s only needed a short computer course to brush up their flying skills for the Max.

Forkner proposed that regulators delete a reference to MCAS in a document outlining the FAA-mandated training sessions, according to Boeing's deferred prosecution agreement.

Forkner is charged with two counts of fraud involving aircraft parts in interstate commerce, and four counts of wire fraud. If convicted, Forkner faces as long as 20 years in prison for each count of wire fraud, and 10 years for each count of fraud involving aircraft parts in interstate commerce.