Risk Formulation of Hull Loss Accidents in Narrow-Body Commercial Jet Aircraft (Boeing 737, Airbus A320, McDonnell Douglas MD82, Tupolev TU134 and TU154 and Antonov AN124)

Abstract

Accidents involving narrow-body aircraft were evaluated statistically for six families of commercial aircraft: Boeing B737, Airbus A320, McDonald Douglas MD80, Tupolev TU134 and TU154 and Antonov AN124. A risk indicator (If) for each flight phase for these families of narrow-body aircraft
was developed based on motion characteristics, duration time and the presence of adverse weather conditions. An estimated risk level was developed based on these risk indicators. Regression analysis indicated very good agreement between the estimated risk level and the accident ratio of hull loss cases per number of delivered aircraft. The effect of time on the hull loss accident ratio per delivered aircraft (HLAR) was assessed for the B737, A320 and MD80 families. Equations representing the effect of time on the HLAR were developed for the B737, A320 and MD80 families, while average values of HLAR were found for the TU134, TU154 and AN 124 families. Estimated risk equations were developed for each family of aircraft, allowing the HLAR to be estimated for any aircraft family, flight phase, presence of adverse weather factor, time of day, day of the week, month of the year, pilot age and pilot flight hour experience. A simplified relationship between the estimated HLAR and unsafe acts by humans was
proposed, with numerical investigation of the relationship suggesting that the HLAR was dominated primarily by the flight phase media.