A Review of UK Military and World Civil Helicopter Water Impacts over the Period 1971–1992 (CAA Paper 96005)

Abstract

This paper reviews accidents to UK Military and World Civil Helicopters over the period 1971 -1992 that have involved impact with water. All occurrences of helicopter water impacts that have resulted in occupants receiving serious or fatal injuries and /or the aircraft sustaining substantial damage have been considered. These criteria meet the minimum requirement for a notifiable accident as defined by Civil and Military airworthiness authorities. Accidents not considered relevant to this study, for example, ground accidents and catastrophic non-survivable accidents, were excluded.

Analyses of accident data were carried out to determine the distribution of impact conditions, accident causes and primary occupant injury mechanisms. The effectiveness of helicopter flotation systems was also reviewed. Mechanical failures were found to be the primary cause of accidents for both military and civil helicopters. These accidents accounted for only a small percentage of occupant fatalities in military helicopter accidents but were the primary cause of fatalities in civil helicopter accidents. Human factor issues (pilot error and disorientation) were found to be the primary cause of occupant fatalities in military helicopter water impacts. In fatal accidents where the cause of death had been established, drowning was found to be the major cause of loss of life.

Helicopter water impacts were categorised into three impact types that accounted for over 70% of all occurrences for which impact conditions were known. Analysis of these impact types is to be undertaken at a later stage in this program to assess the response of helicopter structures to water impact and to evaluate the level of crashworthiness in current designs. From this work, areas where potential design improvements could be made to increase occupant safety will be identified.