Pilot disorientation remains leading cause of fatal crashes, but safety has improved despite growth in rotorcraft fleet

The UK accident rate for light helicopters is falling again after having reached its peak in 1998, the Civil Aviation Authority reveals in a new study. Among fatal accidents, according to the study published in the CAA's Helicopter general aviation safety information leaflet, the most frequent single causal factor was pilot disorientation, and for non-fatal accidents it was mishandling.

In 1998 the rate per 100,000 flying hours for accidents that caused fatal or serious injury was more than 12.5. During the 1990s the rate leapt upwards and averaged above eight per 100,000h, but it fell steadily to about 5.5 in 2001, the most recent year for which the CAA was able to derive a rate.

Pilot disorientation caused more fatal accidents than any other factor during 1997-2001 - eight out of a total of 25, or 32%. Mishandling and mechanical failure were the next most common causal factors, at 20% each.

Among non-fatal accidents, mishandling consistently caused more than half of all events in every year studied. Most of the mishandling accidents occurred in one of the phases of flight close to the ground: landing, manoeuvring - including hovering-in-ground effect - or take-off, with landing usually top of the list. Disorientation was the cause of relatively fewer non-fatal accidents, with the annual proportion between 7% and 16%. Practice forced landings annually caused between 7% and 13% of accidents.

The CAA highlights the degree of skill needed in hovering, hover-taxiing and transitional flight, and warns pilots not to underestimate this. It also advises night fliers to mix visual flying with frequent flight instrument scans.

The study covered helicopters with maximum take-off weights below 2,730kg (6,000lb). The size of the fleet increased from 765 to 942 over the period and hours flown from 135,000h to 154,000h.

Source: Flight International