The National Transportation Safety Board's (NTSB's) Chairman Robert L. Sumwalt retired from government service on Wednesday after nearly 15 years with the agency.

Earlier this year, President Joe Biden nominated NTSB Member Jennifer Homendy to succeed Sumwalt as the board's 15th chair, according to a news release from the agency. Until Homendy’s nomination is confirmed by the U.S. Senate, NTSB Vice Chairman Bruce Landsberg will serve as the board’s acting chairman.

“The NTSB’s role is extremely important: by conducting thorough investigations, our work helps prevent accidents and crashes, reduces injuries, and saves lives,” Sumwalt said. “I’ve been honored to be part of this great agency, and to have served with the dedicated men and women of the NTSB.”

Sumwalt came to the NTSB in August 2006 with his appointment as the 37th member of the agency, where President George W. Bush designated him as vice chairman for a two-year term. In November 2011, he was reappointed by President Barack Obama for an additional five-year term as a board member, and then reappointed again in 2017 by President Donald Trump. That same year, Sumwalt began his tenure as the NTSB’s 14th chairman, and was renominated for a second term as chairman in August 2019.

During his time at the agency, Sumwalt responded to 36 accident sites in all modes of transportation, according to the NTSB. He also advocated for the adoption of hundreds of safety recommendations that the NTSB issues each year.

Prior to joining the NTSB, Sumwalt was a pilot for 32 years, including 24 years with Piedmont Airlines and US Airways, accumulating more than 14,000 flight hours.