question: A few years before 9/11 what did Vice President Gore add to the list of concerns regarding threats against aircraft? answer: Air bombin paragraph: The Federal Aviation Administration (FAA) within the Department of Transportation had been vested by Congress with the sometimes conflicting mandate of regulating the safety and security of U.S. civil aviation while also promoting the civil aviation industry. The FAA had a security mission to protect the users of commercial air transportation against terrorism and other criminal acts. In the years before 9/11, the FAA perceived sabotage as a greater threat to aviation than hijacking. First, no domestic hijacking had occurred in a decade. Second, the commercial aviation system was perceived as more vulnerable to explosives than to weapons such as firearms. Finally, explosives were perceived as deadlier than hijacking and therefore of greater consequence. In 1996, a presidential commission on aviation safety and security chaired by Vice President Al Gore reinforced the prevailing concern about sabotage and explosives on aircraft. The Gore Commission also flagged, as a new danger, the possibility of attack by surface-to-air missiles. Its 1997 final report did not discuss the possibility of suicide hijackings. The FAA set and enforced aviation security rules, which airlines and airports were required to implement. The rules were supposed to produce a "layered" system of defense. This meant that the failure of any one layer of security would not be fatal, because additional layers would provide backup security. But each layer relevant to hijackings-intelligence, passenger prescreening, checkpoint screening, and onboard security-was seriously flawed prior to 9/11. Taken together, they did not stop any of the 9/11 hijackers from getting on board four different aircraft at three different airports. The FAA's policy was to use intelligence to identify both specific plots and general threats to civil aviation security, so that the agency could develop and deploy appropriate countermeasures. The FAA's 40-person intelligence unit was supposed to receive a broad range of intelligence data from the FBI, CIA, and other agencies so that it could make assessments about the threat to aviation. But the large volume of data contained little pertaining to the presence and activities of terrorists in the United States. For example, information on the FBI's effort in 1998 to assess the potential use of flight training by terrorists and the Phoenix electronic communication of 2001 warning of radical Middle Easterners attending flight school were not passed to FAA headquarters. 