CDR. William S. Donaldson, USN (ret.), challenged the official NTSB position on the cause of the crash of TWA Flight 800 in a series of letters to James Hall, Chairman of the NTSB between April 1997 and December 2000. During those four years, CDR. Donaldson worked with other Retired Aviation Professionals, including some previous crash investigators as well as persons inside the NTSB investigation itself. CDR. Donaldson has extensive experience as a Naval crash investigator and he and others concluded that the NTSB's explanation of the Center Wing Tank explosion was not credible. With the help of these other concerned aviation professionals, CDR. Donaldson produced an extensive report on the cause of the crash. The initial Interim Report was delivered to the House Aviation Subcommittee on July 16th, 1998. Since that time a great deal of new information has surfaced.