What happened
On April 5, 2004, a Bell 206B JetRanger-II, registration G-AYMW, was conducting aerial filming for a BBC documentary at the Newgrange Megalithic Passage Tomb in Co. Meath, Ireland. The flight crew, which included the pilot and two passengers, was performing orbits around the mound to capture footage of a presenter.
During the fourth orbit, while the aircraft was transitioning from a hover and performing a gentle right-hand turn, it suddenly experienced a violent, uncommand to the right. The pilot attempted corrective maneuvers, including applying left pedal, reducing collective, and pitching the nose down to gain airspeed, but these actions were unable to arrest the rotation. The helicopter entered a spiral descent and struck a field east of the mound. The impact caused serious injuries to the pilot and minor injuries to the two passengers. The aircraft sustained extensive damage but remained upright, and no fire occurred.
The investigation
An investigation by the AAIU examined the wreckage, witness accounts from the filming crew, and onboard flight footage. Technical inspections of the engine and mechanical components revealed no hardware malfunctions or defects that could explain the sudden movement.
Analysis of the recovered film footage and flight parameters established that the aircraft was operating in a specific flight regime—characterized by high power, a tailwind of approximately 20 knots, and near-zero ground speed—that made it highly susceptible to a phenomenon known as Loss of Tail Rotor Effectiveness (LTE). The investigation also noted that the pilot had not received specific training regarding LTE and was unaware of the phenomenon.
Findings
- The primary cause of the accident was the operation of the helicopter in a flight regime and wind conditions conducive to Loss of Tail Rotor Effectiveness (LTE).
- The pilot's lack of awareness regarding the LTE phenomenon contributed to the inability to recover the aircraft.
- Safety-related information regarding LTE had not been effectively distributed to the pilots operating under the relevant Air Operator Certificate.
- The aircraft's flight manual lacked written procedures for managing LTE.
Safety action
Following the investigation, several safety recommendations were issued, including calls for the Irish Aviation Authority to publicize LTE information within the industry and for aviation authorities like EASA to ensure LTE training is integrated into helicopter pilot syllabi.