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.
Pilot Information
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.
Wreckage Information
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.
Weather
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.
Accident Site
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.