An aviation accident is an occurrence associated with the operation of an aircraft, which takes place between the time any person boards the aircraft with the intention of flight and the time where every person is off the airplane, in which a person is fatally or seriously injured, the aircraft sustains damage or structural failure, or the aircraft is missing or is completely inaccessible. The accident does not have to be flight-related. The causes of aviation accidents are varied, and can be traced back to pilot error, mechanical error, weather, sabotage, or other human error relating to communications or actions taking place before boarding. All of these factors need to be considered when determining liability.