According to our country's classification of fixed-wing aircraft aviation occurrences in civil aviation industry in recent ten years, there is at least one major cause for each occurrence, and there are 2 or more causes for some occurrences. The Aviation Safety Council (ASC) currently divides the causes for aviation occurrences into three categories, those related to human, the environment and aircrafts. People who caused the occurrences are mainly pilots and other personnel (maintenance , air traffic control , organization management , etc.), the environmental causes include the weather, airport facilities, air traffic control and service, day/night and topography etc., and aircraft-related causes include systems and equipment, structures and properties.

         According the ASC's 2012 statistics, human-related aviation occurrences are the most common cause and accounted for 55.5% of all the occurrences (47.2% related to the pilots; 8.3% related to other staffers such as maintenance and air traffic control staff), followed by aircraft-related occurrences that accounted for 33.4%, and environment-related occurrences accounted for 30.6%. Most occurrences are associated with human. This is why the human factor plays an important role in improving aviation safety.