Accident investigations
By mutual agreement, accidents are investigated by the government with jurisdiction over the area where a plane goes down. However, in many instances, the government with legal jurisdiction asks the U.S. National Transportation Safety Board to help or even lead the investigation on its behalf. Governments do so because of the NTSB's experience and expertise, which is recognized the world over. In addition, most of the commercial jets currently in service were designed and manufactured in the United States.
When an accident occurs, the NTSB (or its foreign equivalent) dispatches a "go team" to the site. The NTSB team usually consists of one of the five members of the board plus staff specialists in air traffic control, aircraft maintenance, aircraft operations, aircraft systems and other disciplines useful to determining an accident's cause. Representatives of the various parties to the investigation - usually the aircraft and engine manufacturers, the pilot and controller unions, and the government regulatory agency with jurisdiction over the accident site - also participate in the investigation. All outside parties, however, participate at the invitation of the government authorities leading the investigation, who retain full control over the investigation, oversee all testing and analysis of wreckage, and are solely responsible for determining probable cause.