Injury pattern analysis of helicopter wire strike accidents (-Gz load)

Injury patterns in rotary wing aircraft wire strike accidents were reviewed to determine mechanisms of injury. It was found that U.S. Army Safety Center data showed that between 1 January 1974 and 31 August 1981 there were 167 wire strikes involving Army helicopters which resulted in 60 injuries and 34 fatalities at a cost of $12,809,100. Updated data on all military rotary wing aircraft accidents investigated between 1978 and 1982 were screened by the Division of Aerospace Pathology to determine the mechanisms of injury to flight deck personnel. From 13 December 1978 to 23 June 1982, three types of rotary wing aircraft were in eight fatal accidents. These mishaps accounted for 28 casualties: 14 fatalities and 14 injuries. Aviators comprised 64.4% of the fatalities. Injury pattern analysis showed 100% had major head and neck injuries with 66% having basilar skull fractures. Two-thirds had associated mandibular fractures or evidence of impact forces transmitted through the mandible to the skull. The same number had wedge-shaped chin lacerations from impact with the cyclic control stick. We postulate transmission of lethal impact forces primarily in the +Gz direction through the mandible to the skull. This suggests either improper use and/or failure of the seat and restraint systems.