Boeing CEO Dennis Muilenburg is leaving the company a little more than one year after the first of two fatal crashes involving the company’s 737 Max aircraft, the company announced Monday. Boeing says Muilenburg resigned in its press release, though it also says that the board of directors “decided that a change in leadership was necessary.” The New York Times reports that he was fired.

Muilenburg will be replaced by David L. Calhoun, who currently serves as the chairman of Boeing’s board of directors. Calhoun will also become the company’s president and will retain his chairman post. There will be a “brief transition period” while Calhoun “exits his non-Boeing commitments,” during which the company’s chief financial officer Greg Smith will serve as interim CEO. (Calhoun is currently the head of the private equity arm of major financial firm Blackstone, and spent nearly three decades at General Electric, where ran the conglomerate’s transportation and aircraft engine businesses.) Muilenburg will also lose his board seat.

“[Boeing’s] Board of Directors decided that a change in leadership was necessary to restore confidence in the Company moving forward as it works to repair relationships with regulators, customers, and all other stakeholders,” the company wrote in a statement about the leadership changes.

Boeing has faced great scrutiny after two 737 Max aircraft crashed in the five months (one in October 2018 and another in March 2019), which took the lives of 346 people. The crashes were related to a piece of anti-stall software that Boeing had covertly installed on the planes. Boeing did not properly disclose the software to customers or pilots in an effort to reduce the amount of money and time required for re-training, all as the company tried to keep up with a new aircraft from rival Airbus. The 737 Max has been grounded worldwide since the March crash, and Boeing announced last week that it is indefinitely halting production of the aircraft starting in January.

Muilenburg spent much of 2019 trying to reassure the public of the 737 Max’s safety, while promising shareholders and industry partners that the plane would be back in the air by the end of the year — causing US airlines like Southwest, American, and United to repeatedly revise their predictions for when they’d be able to reintroduce the 737 Max to their respective fleets. But the Federal Aviation Administration has been methodical with the plane’s re-certification, and has even found new safety issues during that process. The agency now isn’t expected to lift the flight ban until February at the earliest.

At multiple points in the last few months — including a New York Times conference in November and congressional hearings in October — Muilenburg said he considered stepping down. But he stuck to the the claim that, since it “happened on [his] watch.” he felt obligated and responsible to “stay on it, work with the team to fix it, to see it through.” Muilenburg said he wanted to remain CEO “as long as the board allows,” despite multiple calls for his resignation.

Things got more complicated for Muilenburg in the last few days as Boeing’s Starliner spacecraft — which is designed to shuttle astronauts to the International Space Station — suffered a major setback during an uncrewed test launch last week. While the spacecraft safely launched and landed, the automated system that was supposed to place it in the correct orbit suffered a glitch, ruining a planned rendezvous with the ISS.