The National Transportation Safety Board (NTSB) is an independent agency responsible for investigation of accidents involving aviation, highway, marine, pipelines and railroads in the United States (except aircraft of the armed forces and the intelligence agencies). It is charged by the U.S. Congress to investigate every civil aviation accident in the United States, as well as significant accidents in other modes of transportation (such as the Big Bayou Canot train disaster near Mobile, Alabama). The organization is also in charge of investigating cases of hazardous waste releases that occur from modes of transportation. Mark Rosenker was appointed as Vice Chairman in 2003 and Acting Chairman in March 2005. He has held the position of the Chairman since August 2006. Robert Sumwalt is the vice chairman. The board is based in Washington, D.C.