In aircraft accident and incident investigation, locating the similar accidents or incidents in the past can help investigators to find out the deep-seated reasons of the accident or the incident. CBR methodology is applied to aircraft accidents and incidents investigation. In the paper, the reasons for the aircraft accident and incident are summarized, and a frame of the accident and incident case is proposed. The historical data of accidents and incidents are used to build a case base. The nearest neighbor method is adopted to search similar cases. Finally, a similarity matching application example is given.