FACTUAL INFORMATION
History of the flight
On 8 September 2004, the owner/pilot of a Robinson Helicopter
Company R44 Raven II helicopter, registered VH-JWX, conducted a
private flight under the visual flight rules (VFR) from Coffs
Harbour, NSW to Eurella Station, Qld. The flight included a landing
at Roma, Qld where the pilot refuelled the helicopter with 180 L of
Avgas from the bulk underground fuel storage supply.1 The pilot then continued to Eurella
Station, located approximately 54 km west of Roma, arriving at 1705
Eastern Standard Time. The pilot shut down the engine and the
property owner boarded the helicopter for a pre-arranged local
flight. The pilot made several attempts to start the engine, during
which it backfired a few times. Once started, the engine seemed to
function normally.
The helicopter departed the homestead at 1725 in a northerly
direction. A person on an adjoining property about 7 km north of
Eurella homestead saw the helicopter operating to the east late in
the afternoon. He reported that the helicopter conducted a number
of takeoffs and landings in what appeared to be the same general
area over a period of about 30 minutes. He saw the helicopter
depart in a southerly direction at about 1830.
The next reported sighting was by a person at Eurella homestead
who, in poor light conditions, saw what appeared to be the
helicopter's landing light to the north of the homestead. The light
moved toward the west of the homestead. Soon after, that person
again saw the light to the west and expected the helicopter to land
at the homestead within a few minutes. However, she became
concerned when the helicopter did not arrive and telephoned an
employee of the property owner to report her concern. The employee
contacted the Australian Search and Rescue organisation (AusSAR)
and search action was initiated. The helicopter was located the
following morning in open, rolling country, 3 km west of Eurella
homestead. The two occupants were fatally injured and the
helicopter was destroyed.
Search and rescue
AusSAR reported that it was notified at 1947 that the helicopter
was overdue. Weather conditions were unsuitable for an air search,
but a surface search was initiated. AusSAR advised that no ELT
signal was received on 8 September by satellite or by aircraft at
high altitude passing within 130 km of Eurella Station. An ELT
signal was detected on two satellite passes early on the morning of
9 September. The signals were identified as originating from
separate locations; one approximately 22 km to the south-west, and
the other approximately 22 km to the south-east, of Eurella
Station. However, those signals were not merged by the satellites
as coming from the same source, so they were of little assistance
in the search. Local aircraft were tasked to begin a search at
daylight on 9 September and the wreckage was located at 0708 by the
crew of a search aircraft. Accident site information
The accident site elevation was about 30 m below the ground
elevation at the homestead. The homestead was not visible from the
accident site.
Figure 1: Aerial view of the accident site
GPS track information
The helicopter was fitted with a fixed global positioning system
(GPS) receiver, and also a handheld GPS receiver mounted in a
cradle on the instrument panel. The fixed receiver did not contain
a non-volatile memory card, but the handheld unit did. Track and
ground-speed data for the occurrence flight was retrieved from the
non-volatile memory card. Altitude information was not retained in
the memory card.
Figure 2 displays the GPS recorded track of the helicopter
overlaid in blue on a 1 in 250,000 scale topographical map of the
area. The local times that the helicopter was at various locations
are depicted.
Figure 2: GPS track overlay, with the landing sites A,
B, C and D
The GPS data showed that the helicopter landed five times during
the flight. Those positions are depicted on the map and are
described as follows:
| Position A | The helicopter landed at 1742 and departed at 1745. There was a water tank adjacent to that location. |
|---|---|
| Position B | The helicopter landed at 1749 and departed at 1752. |
| Position C | The helicopter landed at 1800 and departed at 1802. |
| Position D | The helicopter landed at 1805 and departed at 1807. |
| Position B | The helicopter returned to position B at 1823 and departed at 1827. |
The data indicated that, after the helicopter departed position
B at 1827, it initially tracked almost directly toward the
homestead, but that the track then veered south-west. That track
was clear of the high ground indicated by the 400 m contour near Mt
Muttaby, as depicted on the chart at Figure 2. There are distinct
features in the helicopter's track after 1830, indicating that the
pilot turned toward the homestead on four separate occasions
between 1830 and 1840, only to turn away each time. The accident
occurred on the fifth occasion that the helicopter's recorded track
turned in the approximate direction of the homestead.
Subsequent to the occurrence, an employee from Eurella Station
found that cattle had been moved from the paddock that included
positions A, C, and D, to an adjoining paddock. Those paddocks were
linked by a gate adjacent to position B. The employee recalled that
the property owner had intended to move the cattle to the adjoining
paddock and that the gate adjacent to position B was the gate
through which he would have expected the cattle to be moved.
Pilot information
The pilot held an air transport (aeroplane) pilot licence and a
command multi-engine instrument rating. He had extensive aeroplane
flying experience, including regular public transport turbo-jet
aircraft and corporate turbo-jet aircraft operations in Australia
and overseas. His aeroplane flying experience exceeded 10,000 hours
and included 1,418 hours of night flight and 711 hours of
instrument flight.
The pilot obtained a private pilot (helicopter) licence on 23
September 1998 and had about 582 hours helicopter experience. He
obtained a night VFR (helicopter) rating on 12 September 2000 and
since that date had recorded about 11 hours helicopter night
flight. Almost all of the logged flights were in the Sydney
metropolitan area. Helicopter night flying recorded by the pilot in
the two years prior to the occurrence was 0.4 hours on 23 August
2004 and 0.6 hours on 26 August 2004. That night flying most likely
occurred during the latter stages of flights to the Sydney
metropolitan area.
There was no record of the pilot having received any specific
training in operating helicopters in remote areas or dark night
conditions where there was little or no ambient lighting. No
helicopter instrument flight time was logged.
The pilot held a valid medical certificate. Post-mortem and
toxicology examinations did not reveal any pre-existing condition
that might have affected the pilot's ability to safely conduct the
flight.
Helicopter information
The pilot purchased the helicopter new in early August 2004. At
the time of the occurrence the helicopter had operated for 34.1
hours. The maintenance release was valid and the documentation
indicated that all applicable maintenance and regulatory
requirements had been met.
The helicopter was equipped and certified for night VFR
operations. Instrumentation included an airspeed indicator,
artificial horizon, sensitive pressure altimeter, turn coordinator,
horizontal situation indicator, global positioning system
indicator, and vertical speed indicator.
The helicopter was equipped with twin landing lights in the
lower nose section. The lights were fitted with 100 watt spot
globes and, according to the Aircraft Flight Manual, were 'set at
different angles to increase the pilot's field of vision'. Both
lights were activated by the one switch which was mounted on the
cyclic control centre post.
A row of eight amber warning lights located at the top of the
flight instrument panel included a clutch warning light. A further
six warning lights were positioned at the top of the centre
pedestal.
The helicopter's engine was coupled to the rotor drive system
via four double-stranded vee-belts. After engine start, an electric
actuator would tension the belts when the pilot engaged the clutch
switch. The actuator sensed belt tension and was automatically
energised when the tension was less than required. The clutch
warning light would illuminate whenever the clutch actuator circuit
was activated. The Aircraft Flight Manual included a note regarding
the clutch in Section 3, Emergency Procedures. The note stated that
stretching of the belts often resulted in illumination of the
clutch warning light for brief periods as the drive actuator
readjusted belt tension. The note also included actions that the
pilot should take after 7 or 8 seconds of illumination of the
clutch light. One of those actions was to pull the clutch circuit
breaker.
The helicopter was fitted with a Pointer (TSO-C91A) Model
3000-10 emergency locator transmitter (ELT). The unit was located
on the left side of the rear fuselage.
The total flight time from Roma until the time of the occurrence
was about 1 hour 35 minutes. Assuming a fuel usage rate of 60 L per
hour, approximately 95 L would have been consumed during that time.
On that basis, approximately 95 L should have remained at the time
of the occurrence.
Wreckage information
opposite to the helicopter's direction of travel at impact. The
impact severely crushed most of the cabin area and deformed the
fuselage and tail boom structures.
Two distinct main rotor blade impact marks on the ground forward
and to the right of the initial nose impact position, and the
damage to the main rotor blades, indicated that the rotor blades
were being driven by the engine at impact. The tail-rotor system
was intact and there was no evidence that the fuselage was yawing
at impact. There was no indication that the helicopter had struck
any of the trees in the vicinity of the impact site.
The left fuel tank ruptured during the impact sequence and was
empty. The right fuel tank was also empty. With the helicopter
lying on its left side, the right fuel tank vent line was at the
lowest part of the tank, and would have allowed fuel to drain out.
There was a strong smell of Avgas in the vicinity of the wreckage
on the day after the accident.
The hydraulic system switch was found in the ON position.
Instrument panel light globe and instrument examination
confirmed that electrical power was available to the instruments.
There was no evidence of malfunction of any of the instruments.
The six warning lights at the top of the centre pedestal were
destroyed by impact forces, preventing an assessment being made of
their status at impact. The eight warning lights at the top of the
flight instrument panel were intact. Examination of those light
globes revealed stretching of the clutch warning light filament.
Stretching indicates that the filament was hot and that electrical
power was applied to the globe when it was subject to forces during
the impact sequence. It was not possible to determine the length of
time that the globe had been illuminated. Filament stretch was not
evident in any of the other seven warning light globes from the top
of the instrument panel.
Damage to the landing light globes prevented any assessment
being made regarding their status at the time of the occurrence.
The damage to the landing light switch indicated that it was in the
ON position at impact.
The circuit breaker panel was destroyed by impact forces. The
clutch actuator fuse was serviceable. The wreckage examination did
not reveal any fault in the clutch system. Although the circuit
breaker panel was destroyed, the evidence of electrical power to
the clutch warning light indicates that the circuit breaker was
engaged, and therefore the system was powered at the time.
The coaxial cable from the ELT unit to the external antenna had
separated at the connector to the antenna base on the inside of the
antenna mounting panel. The separation of the coaxial cable trapped
the transmitted signal within the fuselage compartment. That
rendered the ELT unit ineffective and prevented satellite detection
of the signal. The separation of the cable appeared to have been as
a result of impact forces. As a result, the search and rescue
effort was significantly affected.
Specialist examination of the ELT revealed that it had activated
upon impact and, when connected to a suitable antenna, was capable
of transmitting a normal signal.
The engine was test run after removal from the wreckage and
operated normally. The hydraulic pump and three hydraulic servos
that formed part of the main rotor flight control system were
removed from the wreckage for functional testing. The tests were
conducted at the helicopter manufacturer's facility in the USA and
supervised on behalf of the ATSB by a representative from the US
National Transportation Safety Board. The tests confirmed that the
hydraulic system components met the specifications for normal
operation.
Meteorological information
Documents found in the helicopter included an Area 41 weather
forecast valid from 0900 to 2100 on the day of the occurrence and
the Roma terminal area forecast (TAF) valid from 1200 to 2400 on
the day of the occurrence.
The area forecast indicated that the weather in the vicinity of
Eurella Station would include areas of rain with locally moderate
falls, scattered showers and isolated thunderstorms. The Roma TAF
indicated that between 1500 and 2400 there would be 60 minute
periods in which the visibility would be 2 km in heavy rain, with
broken cloud2 at 700 ft.
An analysis by the Bureau of Meteorology indicated that during
the late afternoon on the day of the occurrence, a surface trough
was located from Camooweal to St George, with cold south-west winds
to its west and northerlies to its east. The surface trough
combined with an upper level trough over the southwest of the state
to bring a large cloud band with widespread rain and isolated
thunderstorms to the interior. The analysis of satellite imagery
and synoptic reports, concluded that there was a high probability
of rain in the Eurella Station area around the time of the
occurrence, and most likely greater than 5 oktas of cloud cover.
However, because the nearest weather radar station was about 200 km
distant at Charleville, the amount of cloud cover in the area of
the occurrence could not be confirmed.
Persons at and near Eurella Station variously reported that the
weather conditions during the day of the accident were windy, with
heavy cloud and showers.
Astronomical information
According to information published on the Geoscience Australia
website, sunset and twilight times at Eurella Station on the day of
the occurrence were:
Other information on the website indicated that the moon set at
1409 and was 79 degrees 31 seconds below the horizon at 1830 that
evening.
Helicopter night VFR
The pilot's night VFR (helicopter) rating authorised him to act
as pilot in command of private or aerial work flights at night
under the VFR. Once issued, a night VFR rating remained permanently
valid. To exercise the privileges of the rating, a pilot needed to
complete a 1-hour night flight during the previous 12 months and
one takeoff and landing at night during the previous 6 months.
There was no requirement for the holder of a night VFR rating to
have any recent instrument flight time prior to conducting a flight
at night.
A pilot operating under the VFR at night was required to operate
in visual meteorological conditions that included a minimum of 5 km
visibility. The Aircraft Flight Manual, Section 2, Limitations,
included the following statements:
VFR operation at night is permitted when landing, instrument,
and anti-collision lights are operational. Orientation during night
flight must be maintained by visual reference to ground objects
illuminated solely by lights on the ground or adequate celestial
illumination.
At the time of the occurrence there was a 1,000 watt flood light
on each of the northern and western walls of Eurella homestead, as
well as lights in other buildings. However, there were many trees
in the vicinity of the homestead, some of which were higher than
the homestead roof. Depending on the altitude and position of the
helicopter, the trees could have prevented those lights being seen
from the helicopter (Figure 1). There was no other lighting in the
general area, including at the airstrip adjacent to the homestead.
The homestead lights, in effect, formed a 'point' source of
light.
Spatial Disorientation
Spatial disorientation refers to a situation in flight in which
the pilot fails to sense correctly the position, motion or attitude
of the aircraft. When the condition is fully developed, the pilot
is unable to tell which way is 'up'.
The risks of non-instrument rated pilots flying in conditions in
which they are not able to orientate the aircraft by visual
reference have been well known for over 50 years. During testing
conducted on a group of non-instrument rated pilots, the average
time before loss of control of the aeroplane, after visual
reference was lost, was 178 seconds.5
US FAA Advisory Circular 60-4A, Pilot's Spatial Disorientation,
was published in 1983 and was intended to inform pilots of the
hazards associated with disorientation caused by loss of visual
reference with the external environment. It included the following
information:
Tests conducted with qualified instrument pilots indicate that
it can take as much as 35 seconds to establish full control by
instruments after the loss of visual reference with the
surface.
The helicopter manufacturer issued a safety alert and safety
notices (SN) as a result of various occurrences and incidents, and
included those notices in the Aircraft Flight Manual Section 10,
Safety Tips. Two of the notices related to night flight - SN-18
Loss of Visibility Can Be Fatal, and SN-26 Night
Flight Plus Bad Weather Can Be Deadly (see Appendix A). Safety
notice SN-18 stated in part:
Helicopters have less inherent stability and much faster roll
and pitch rates than airplanes. Loss of the pilot's outside visual
references, even for a moment, can result in disorientation, wrong
control inputs, and an uncontrolled crash.
Appendix A
1.On the
day of the occurrence, other aircraft were refuelled from the Roma
bulk fuel storage. The ATSB received no reports of fuel quality
related problems involving those aircraft.
2.
Forecast cloud was explained as 'few'-1 to 2 oktas (okta - a unit
of visible sky area representing one-eighth of the total area
visible to the celestial horizon), 'scattered'- 3 to 4 oktas,
'broken'- 5 to 7 oktas and 'overcast'- 8 oktas.
3.
Sunset is defined as the instant in the evening under ideal
meteorological conditions, with standard refraction of the sun's
rays, when the upper edge of the sun's disk is coincident with an
ideal horizon.
4.
Ending of evening civil twilight is defined as the instant in the
evening when the centre of the sun is at a depression angle of six
degrees below an ideal horizon. In the absence of moonlight,
artificial lighting or adverse atmospheric conditions, the
illumination is such that large objects may be seen, but no detail
is discernible.
5.
Bryan, L.A., Stonecipher, J.W. & Aron, K. 1954. 180-degree
turn experiment. University of Illinois Bulletin. 54(11),
1-52.