Sean O’Keefe, the chief executive of Airbus Group’s Herndon-based North American unit will step down in March, the company said Tuesday.

O’Keefe became chief executive of the unit, which was previously called EADS North America, in late 2009. The former NASA administrator is departing to “fully address ongoing medical issues” related to a 2010 aircraft accident in Alaska, the company said.

O’Keefe and his son survived the crash, which killed former U.S. senator Ted Stevens (R-Alaska).

O’Keefe said in a statement that he recently underwent another operation related to complications from the crash.

“While the outcome of this latest surgery is positive, it’s evident that the new complications will preclude the devotion of my best efforts to the duties of CEO of Airbus Group, Inc.,” he wrote. “Following reliable medical advice, it is increasingly apparent that I need to focus on a more aggressive rehabilitation regime.”

Airbus said Allan McArtor, chairman of Airbus Americas, Airbus Group’s commercial aircraft division in North and South America, will take over the job. He joined Airbus in 2001 after serving as head of the Federal Aviation Administration, founder of Legend Airlines and an executive at Federal Express, better known as FedEx.

McArtor takes over at a time of significant change for the company.

Starting this year, EADS was rebranded as Airbus Group. The company now includes Airbus, which focuses on commercial aircraft; Airbus Defense and Space, which combines the Cassidian, Astrium and Airbus Military brands; and Airbus Helicopters, which includes commercial and military helicopter work.

In recent years, the North American defense unit has struggled to grow its presence. It suffered a key setback when it lost a massive deal to build a next-generation aerial refueling tanker, ultimately won by Boeing in 2011.

O’Keefe, who has said in the past that the contractor is committed to the U.S. market, said in his statement that information on the Airbus Group reorganization in the United States will “continue to emerge” through the first half of this year.