Somchanok Tiabtiamrat and Supachok Wiriyacosol

pp. 489 - 496

Abstract

Accidents with narrow body aircraft were statistically evaluated covering six families of commercial aircraft including
Boeing B737, Airbus A320, McDonnell Douglas MD80, Tupolev TU134/TU154 and Antonov AN124. A risk indicator for each
flight phase was developed based on motion characteristics, duration time, and the presence of adverse weather conditions.
The estimated risk levels based on these risk indicators then developed from the risk indicator. 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 was assessed for B737, A320 and MD80. Equations
representing the effect of time on hull loss accident ratio per delivered aircraft were proposed for B737, A320, and MD80,
while average values of hull loss accident ratio per delivered aircraft were found for TU134, TU154, and AN 124. Accident
probability equations were then developed for each family of aircraft that the probability of an aircraft in a hull loss accident
could be estimated for any aircraft family, flight phase, presence of adverse weather factor, hour of day, day of week, month
of year, pilot age, and pilot flight hour experience. A simplified relationship between estimated hull loss accident probability
and unsafe acts by human was proposed. Numerical investigation of the relationship between unsafe acts by human and
fatality ratio suggested that the fatality ratio in hull loss accident was dominated primarily by the flight phase media.