UNDERSTANDING THE ROLE OF HUMAN ERROR IN AIRCRAFT ACCIDENTS

The commercial aviation industry has achieved an enviable record of safety, but accidents still occur. In roughly two-thirds of aircraft accidents, aviation's human link receives the blame, and the proportion of accidents attributed to human error has not changed appreciably in 20 years. Most human error that leads to accidents surfaces in the performance of flight crews and air traffic controllers. The strategies used to address human error can be placed in two categories: introduction of technology that reduces the role of humans in the system and changes to the system and training suggested by human factors considerations. The pursuit of these approaches has largely become distinct, but they are both characterized by several basic assumptions. Both technologists and human factors specialists attribute human error to human fallibility and accept in varying degrees the inevitability of human error. Both accept the notion that humans are the most unreliable element in aviation. Both place emphasis on flight crews and air traffic controllers. Supporters of both approaches hold doubts as to the value of the other; in particular, the technologists view human factors as being too untidy to be the basis of design. The system that fails in an aircraft accident can be divided into animate (human) and inanimate components. If assumptions are reconsidered, there are mechanisms by which the inanimate system can contribute to causing the human error that leads to accidents. There is a spectrum of possible accident causes between the extremes of entirely human error or entirely inanimate system malfunction. Current interventions are heavily weighted toward the human error end of the spectrum, but this paper suggests an additional approach to interventions that alleviates system problems that cause human errors.