History of the Flight
The Agusta /Bell 47G-2A1 helicopter, registered VH-FLI, was borrowed by the pilot to fly his sister to her wedding at the family property near Holbrook NSW.
The pilot arrived at the helicopter owner's property around 0900 Eastern Standard Time on the day of the accident, and with assistance from the owner, he completed a pre-flight inspection of the helicopter. The pilot subsequently conducted a number of flights on the day of the accident.
At about 1730, the pilot and his sister boarded the helicopter and departed in an easterly direction. The pilot then followed a route that ran adjacent to the Holbrook to Jingellic road in order to remain near the car being driven by his mother.
Witnesses reported that the helicopter was flying at a very low height as it neared Chinamans Gap. At approximately 1745, when the helicopter was about 6 km from its destination, it struck a powerline, pitched nose down and impacted the ground on its left side. The impact and the subsequent fire fatally injured the occupants and destroyed the helicopter.
The pilot held a Commercial Pilot Helicopter licence, issued in September 1993. The pilot's Bell 47 qualification had been gained in August of that year. The pilot had also served as a helicopter pilot in the Royal Navy, the Australian Army, and the Royal Australian Navy. His military pilot logbooks indicated that he had significant helicopter low-level flying experience and his civilian logbook showed that he had completed civilian helicopter low flying training. As part of that training he had been alerted to the dangers of powerlines during low-level flight, and of the need to carry out a reconnaissance of an area before conducting a low-level flight. The pilot had not previously flown the route followed to the property where the wedding was to be held.
Records of his Bell 47 flying experience were incomplete, with the last recorded flight being in August 1994. However, witnesses reported that he had flown this Bell 47 on numerous occasions since that time. The pilot's total recorded Bell 47 flying time was 23.8 hours. His friends and colleagues indicated that he was a careful pilot.
While the pilot was required by the Civil Aviation Safety Authority to have "visual correction for distant vision" during commercial flights, his uncorrected vision was adequate to meet the private pilot licence standard. No evidence was found that the pilot was wearing spectacles at the time of the accident. Witnesses indicated that the pilot had received adequate rest prior to the flight. There was no evidence found to indicate that the pilot's performance was adversely affected by any pre-existing physiological condition.
Examination of the wreckage indicated that the powerline first entered the area between the skid landing gear and the cockpit floor, severing the landing light before contacting the landing gear forward cross tube. The main-rotor blades severed the tailboom approximately 1 m forward of the tail rotor assembly. The two fuel tanks, which had detached during the initial impact, burst open. The main wreckage of the helicopter was subjected to an intense fire fed by the fuel from the burst tanks.
Examination of the wreckage revealed no mechanical faults that may have contributed to the accident. No wire-strike protection devices were fitted to the helicopter.
The wind was light and variable, visibility was 40 km, and there was 1 to 2 octas of high-level cloud. The temperature was 29 degrees Celsius, the dew point was 2 degrees Celsius and the QNH was 1012hPa. The likelihood of carburettor icing at the time of the accident was extremely low. The sun was behind the helicopter at the time of the accident.
The helicopter had impacted the tarmac road surface, just beyond a road cutting in a ridgeline. The powerline ran approximately 90 degrees to the helicopter's flight path and was strung between two poles that were each located on peaks of the ridge. The distance between the two poles supporting the powerline cables was about 900 m. At the point where the helicopter contacted the powerline cables, the cables were at a height above the roadway of approximately 31 m. The powerline had been erected several years before the accident and had developed a dull oxidised finish. There were no high visibility devices on the powerline cables to make them easier to detect from aircraft. No maps were found with the wreckage, and due to the relative recency of the erection of the powerline they did not appear on topographic maps of the area.
Pilots who regularly flew in the area indicated that the powerline was difficult to see from the air because the cables blended with the background of trees and other vegetation. One pilot advised that he had previously reported this to the power transmission company, suggesting that the powerline cables were a hazard to aircraft and that something should be done about making them more visible. The power transmission company reportedly replied that the height of the powerline was lower than the minimum height for powerlines requiring the fitment of high visibility devices as laid down in Australian standards.
Regulations and Standards
The Australian standard relating to cables and their supporting structures, required them to be marked with warning markers if the height of the lines exceeded 90 m above ground level. There was, however, a proviso that this standard could be varied if an air operator referred the matter to the appropriate Regional Airspace Advisory Committee for resolution.
The Civil Aviation Regulations require a helicopter that is not over a town or populous area, to remain a minimum of 500 ft above ground level. Further, the helicopter must be 500 ft above any obstacle within a 300 m radius of the helicopter's flight path, unless taking-off or landing.
The powerlines were difficult to see from the air due to their dull surface and the non-contrasting background. Australian standards did not require the mounting of high visibility devices on the powerlines in this area, however, their fitment may have improved the powerlines' visibility from the air. Although one pilot had reported his concerns to the power transmission company prior to discussions with the investigation team, he was not aware that he could refer the matter to the appropriate Regional Airspace Advisory Committee for resolution.
The pilot was qualified to fly the helicopter below a height of 500 ft, however, on this occasion he had not obtained authorisation from the Civil Aviation Safety Authority to do so. The pilot had not previously flown the route followed to the property, and without prior reconnaissance or a detailed map of the area he was unlikely to have been aware of the powerline's existence.
- The pilot was flying the helicopter at a low height above the ground.
- The helicopter collided with a powerline.
Local safety action
Following this accident, the power transmission company attached, high visibility, spiral dampener devices to the replacement powerlines in the area of the Chinamans Gap road cutting.
|Date:||20 February 1999||Investigation status:||Completed|
|Time:||1800 hours ESuT|
|Location:||26 km ESE Holbrook, (ALA)|
|State:||New South Wales||Occurrence type:||Collision with terrain|
|Release date:||21 December 1999||Occurrence category:||Accident|
|Report status:||Final||Highest injury level:||Fatal|
|Aircraft manufacturer||Agusta, S.p.A, Construzioni Aeronautiche|
|Type of operation||Private|
|Damage to aircraft||Destroyed|
|Departure point||"Oxton Cottage", NSW|
|Departure time||1735 hours ESuT|
|Role||Class of licence||Hours on type||Hours total|