The NTSB considers the party system crucial to the investigative process , as it provides the NTSB with access to individuals with specialized expertise relevant to a particular investigation . However , use of the party system is not without controversy . The NTSB invited The Boeing Company to participate as a party to the investigation of the crash of TWA Flight 800 , a Boeing 747 , in 1996 . While the NTSB relied on Boeing 's sharing of expertise , it was later determined that Boeing had withheld from the NTSB a study of military versions of the 747 that investigated flammable vapor combustion in the center fuel tank . Boeing had told the NTSB that it had no studies proving or disproving the vapor combustion theory . In response to political pressure after the Boeing incident , the NTSB commissioned the nonprofit Rand Corporation to conduct an independent study of the NTSB 's aircraft investigation process
crash of TWA Flight 800
TWA Flight 800
National Transportation Safety Board