Effect of improved helicopter crashworthiness design on helicopter accident statistics

In order to minimize the severity of helicopter accidents, the modern generation of helicopters, the UH-60 Blackhawk and the AH-64 Apache, have been designed with more stringent crashworthiness criteria than were the early generation helicopters. These more stringent criteria impose weight and cost penalties on the helicopter. The question has been raised as to whether these penalties are justified. This study compares the crash experience of these modern generation helicopters with the crash experience of the early generation helicopters. It shows that the increased crashworthiness criteria of the modern generation helicopters are justified by the accident statistics as follows: (1) For the modern helicopters, there is a reduced severity of injury for a given crash velocity relative to the older generation helicopters; (2) the modern helicopters experience significantly fewer (50 percent less) fatalities and/or major injuries per million flight hours than do the early generation helicopters; (3) the modern helicopters experience a significantly smaller probability (50 percent less) of a fatality and/or major injury, given a Class A/B accident, than do the early generation helicopters; and (4) each class of helicopters experiences a reduction in the number and severity of accidents with increased maturity, i.e., increased years in service. The comparisons above are made at equal years in service for the two classes of helicopters. Based on the above, the author concludes that the more stringent crashworthy design criteria of the modern generation helicopters are justified. The variation with design crash velocity of crash-fatality and crash-injury rate per million flight hours, and of the probability of a fatality and/or major injury, given a Class A/B accident, have been established. These trends can be used to predict the effect of different crash design requirements on the accident statistics of future helicopters.