What happened
On 20 May 2001, a Bolkow BO-1SDBS-4, registration G-DCCH, was performing a private air ambulance mission near Dunchideock, near Exeter. The crew was tasked by Ambulance Control to locate a car that had overturned, with reports that occupants were trapped. While searching the area in coordination with land-based emergency services, the pilot identified a suitable landing site in a large, sloping grass field adjacent to a minor road.
As the pilot conducted a slow approach into the southeast corner of the field, the aircraft was subject to a gust of wind that caused the tail to yaw to the left. The pilot immediately experienced a high-frequency vibration through the pedals, indicating a tail rotor strike. The tail rotor subsequently detached from the aircraft. In an attempt to manage the resulting yaw, the pilot lowered the collective pitch. The helicopter struck the ground heavily from an altitude of approximately 35 feet in a nose-down attitude. The aircraft remained upright on the slope. The three crew members on board sustained minor injuries and were transported to the hospital as a precaution.
The investigation
Investigators examined the cockpit environment and the sequence of events leading to the impact. It was established that the pilot was managing a high volume of radio communications, including traffic information from Exeter ATC and coordination with the land ambulance. During the period when the pilot acknowledged the ATC call, the aircraft's intercom was inhibited.
While a paramedic in the front left seat attempted to warn the pilot of the tree's proximity via the intercom, the pilot did not hear the warning. The investigation found that the pilot's attention was divided between searching for an access route through a hedgerow and monitoring multiple radio frequencies. Consequently, the pilot did not notice a northerly drift that moved the aircraft toward the isolated tree on the western edge of the landing area.
Findings
- The tail rotor struck a tree located on the western edge of the landing area.
- The pilot's attention was diverted by the simultaneous need to monitor air traffic information and ambulance radio communications while searching for a landing access route.
- The aircraft's intercom was unavailable to the crew during the pilot's radio transmission to Exeter ATC.
- A wind gust contributed to the lateral drift toward the obstacle.