The National Transportation Safety Board or NTSB is an independent investigative agency in the United States government. The NTSB investigates civil transportation accidents, which can be highway accidents, ship and marine accidents, pipeline and railroad accidents.
In 1988, Phillip Devine, an maintenance chief with United Airlines, placed an inquiry into any accidents involving a C-97 Stratofreighter or a Boeing 377 Stratocruiser for Dirk Pitt. The inquiry came back with no C-97s or Boeing 377s were listed as missing.