One of two Boeing Co technical pilots who described flaws in a crucial flight control system in leaked 2016 instant messages has been transferred to a new job at the U.S. planemaker, two people familiar with the matter said on Tuesday.

Boeing shares tumbled after the conversation between the employee, Patrik Gustavsson, and then-chief technical pilot Mark Forkner became public on Oct. 18.

The comments by Forkner, who has since left Boeing, were among those pinpointed by U.S. lawmakers in hearings in Washington as evidence Boeing knew about problems with flight control software well before two crashes of its 737 MAX aircraft in October 2018 and March 2019 killed 346 people.

Gustavsson was a technical pilot for the 737 program at the time Forkner told him the jetliner's so-called MCAS stall-prevention system was "running rampant" in a flight simulator. Gustavsson later replied that other pilots had kept them "out of the loop" on changes to MCAS.

Gustavsson has been transferred in the last two weeks to Boeing's Test & Evaluation group, a source familiar with the matter said. A second source confirmed that he was recently moved to a new job but had no details.

The Test & Evaluation group includes pilots who put the actual 737 MAX aircraft through hundreds of hours of test flights before the jetliner entered service.

If Gustavsson was made a test pilot in the group, he would have likely received a 15%-20% raise, the first source said.

It was unclear why he changed jobs.

A Boeing spokesman declined to comment.

Before the change, Gustavsson was a 737 technical pilot for roughly 5 years, according to his LinkedIn profile. He was named 737 Chief Technical Pilot in 2018, his profile says.

Gustavsson and Forkner were part of a team that worked on the flight manuals airlines have used since the 737 MAX entered service in 2017, and fielded operations and systems questions from dozens of global airlines operating thousands of 737 aircraft globally, former employees told Reuters in late October.

Forkner also worked to identify and fix glitches on the 737 MAX simulator. He left Boeing in 2018 and is now a First Officer at Southwest Airlines, according to his LinkedIn profile.

Before Boeing, Gustavsson spent 11 years in various roles such as simulator instructor at Ryanair Holdings PLC, according to his LinkedIn profile.

Separately, Boeing said on Tuesday that Conrad Chun was named vice president of communications for its commercial airplanes division, taking over from Linda Mills, who is leaving the company.