Hersman will continue in her role until April 25, when vice chairman Christopher Hart will take over on an interim basis, a press release from the NTSB said.
Calling the new post a "dream job," Hersman said she was proud of the changes in the "landscape of transportation" since she joined the NTSB.
"The NTSB and often, the families of victims, have served as critical catalysts for bringing about change after a terrible accident," she said. "It has been an honor to be associated with a noble mission that has at times inspired and evoked passion and at other times, been in the crosshairs of controversy, as real change doesn’t come without a cost."
Hersman, who was once on President Obama's short list for Secretary of Transportation, was on the scene for more than 20 accident investigations -- most recently, the Asiana Airlines crash in San Francisco last year.
The NSC, a nonprofit group founded in 1913 and chartered by Congress, works to prevent injuries and deaths at work, in communities, and on the roads.
[NTSB Safety Compass]