The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress to investigate every civil aviation accident and significant accidents in all other modes of transportation, including highway, railroad, marine, pipeline and hazardous materials. The NTSB is not part of the Department of Transportation. The NTSB uses a similar investigative process for all the transportation modes, regardless of the complexity of the accident or the vehicle systems involved. The objective of this paper is to document the NTSB’s process for investigating all crashes with a focus on vehicle and system automation, particularly in the highway mode where the transition to automated control systems is occurring in the current vehicle fleet.

The NTSB follows a systematic investigative process for all modes of transportation, with modal specialists leveraging support from in-house research and engineering laboratories. The paper explains each step of the investigative process from start to finish, including the initial crash notification, launch selection, the on-scene phase, the party process, recorded data, laboratory capabilities, investigative hearings, factual reports, technical reviews, analysis reports, safety recommendations, and the final NTSB products. The paper will highlight the breadth and diversity of the NTSB disciplines covered throughout the investigation:​ biomechanical engineers, survival factors specialists, human factors experts, meteorologists, structural engineers, materials scientists, recorder engineers, medical and toxicological specialists, and vehicle dynamics engineers. Examples from NTSB investigations are highlighted to elucidate the investigative process and its application to vehicle and system technologies. Measures of NTSB effectiveness are discussed, including recommendation acceptance rates and outreach efforts.

The goal of the NTSB investigation is to determine the probable cause of the crash and to issue safety recommendations to prevent future crashes or reduce the severity of future crashes;​ the goal is not to assign blame or determine fault. Through a formal system involving designated parties to the investigation, the NTSB leverages the technical knowledge of organizations associated with a crash, such as the operators, manufacturers, unions, maintenance operators, and regulatory agencies. The party system ensures that all factual information is collected, agreed to, and reported correctly. This process enables the party members to obtain knowledge of critical aspects of a crash investigation in a timely manner. The NTSB takes full responsibility for determining the probable cause and making recommendations;​ this unbiased reporting fosters public trust that safety is being properly addressed. The NTSB’s investigative process has successfully documented the probable cause and issued safety recommendations for complex investigations in all transportation modes. Case examples from recent investigations will serve as examples of the investigative process:​ the crash during landing of Asiana Flight 314, the Washington Metro Area Transit Authority red line crash, and the high-speed derailment of the Amtrak train in Philadelphia, PA.