Transportation Safety Board's Hall to Step Down 

                 WASHINGTON (Reuters) - National Transportation Safety Board Chairman Jim Hall, who headed the agency through a series of high-profile air accident investigations over the last seven years, said Monday he will leave Jan. 18.

During Hall's tenure, the safety board launched a massive investigation of two of the most complex air crashes in U.S. history -- the explosion of a TWA Boeing 747 near New York in 1996 and the 1994 crash of a US Airways Boeing 737 near Pittsburgh.

An electrical fault sparking a blast in TWA Flight 800's center fuel tank was deemed the likely cause, despite early fears that a bomb or missile could have been the cause.

The Pittsburgh crash was blamed on a design fault in the rudder after lengthy analysis of hydraulic systems, pilot training and performance. Improvements in aircraft design have flowed from both investigations.

Hall, a Democrat from Tennessee who ran Vice President Al Gore (news - web sites)'s Senate campaigns,  joined the safety board in 1993 and became chairman in 1994.

Recently appointed safety board member Carol Carmody, another Democrat, is likely to be named by President Clinton (news - web sites) as acting chairman. However, President-elect George W. Bush (news - web sites) is expected to nominate someone of his own choice.

``The men and women of the Safety Board serve our nation with dedication and distinction. I will miss my association with them,'' Hall said in his resignation letter to Clinton.

Other major investigations under Hall have included the crash of a Valujet plane into the Florida Everglades in 1996, the collision of an Amtrak train and a commuter train in Maryland in the same year, the loss of a plane piloted by John F. Kennedy Jr. in 1999 and the crash of an EgyptAir jet off the U.S. East Coast in 1999 that may have been a deliberate act by one of the crew.

Under Hall, the care of victims' families improved greatly. A Family Affairs Office was established within the safety board and 1996 passage of the Aviation Family Assistance Act gave the board authority to coordinate federal services to relatives. Hall's legacy will also include a new training center for accident investigators at George Washington University's Loudoun County, Virginia, campus where the reconstructed wreckage of TWA 800 will eventually be housed.

The safety board investigates every civil aviation accident in the United States and significant events in other modes of transportation including rail crashes, major highway accidents, maritime disasters and pipeline accidents.