HISTORY OF THE FLIGHT
At 2109 EST on 17 October 2003, a pilot, crewman and paramedic
operating a Bell 407 helicopter, registered VH-HTD, were tasked to
fly from Mackay to Hamilton Island, Queensland, to transport an
injured patient back to Mackay. The flight was planned as a visual
operation at night and departed at approximately 2135. When the
helicopter did not arrive at Hamilton Island, a search was
initiated and a search helicopter crew later sighted the wreckage
of HTD floating in the water. Some time later, marine rescue craft
arrived and commenced a search, but no survivors were
located.
Air Traffic Services recorded radar information indicated that the
helicopter, while tracking north-northwest, was flying between
2,900 ft and 3,100 ft for the majority of the flight. It
subsequently climbed to 3,700 ft and performed a number of abrupt
manoeuvres before descending to 2,700 ft and disappearing from
radar coverage.
A weather report provided by the Bureau of Meteorology indicated
that, at the time of the occurrence, there was scattered cloud at
2,900 ft and broken cloud at 9,800 ft and no moon. Moonrise that
night was expected to occur at 6 minutes after midnight.
During the investigation, ATSB investigators conducted a night
flight in similar environmental conditions, at the same altitude
and track towards Hamilton Island. They reported that while
tracking north-northwest in the area of the accident, it was very
dark with no ground or celestial illumination visible and no
discernible horizon.
SAFETY DEFICIENCY
During the course of the investigation, a safety deficiency
relating to visual operations at night was identified.
General requirements for visual operations are contained in
Aeronautical Information Publication (AIP) ENR 1.2 paragraph 2.6.
Flights under the Visual Flight Rules (VFR), for both day and night
operations, are required to be conducted in accordance with various
provisions, including those relating to flight visibility and
distance from cloud. When flying outside controlled airspace below
10,000 ft, the required flight visibility is 5,000 m. There is also
a requirement for 1,500 m horizontal and 1,000 ft vertical
separation from cloud when flying above 3,000 ft above mean sea
level, or 1,000 ft above ground level (whichever is the higher).
Pilots operating at or below 3,000 ft are required to remain clear
of cloud and in sight of ground or water.
The AIP does not require pilots to consider the amount of external
visual reference that is likely to be available for a visual flight
conducted at night. In particular, it does not require pilots to
consider the amount of celestial illumination, the amount of
terrain lighting, or the presence of a visual horizon either
enroute, or at the destination aerodrome. Pilots are also not
required to consider the presence of high-altitude cloud along the
planned route that may obscure celestial illumination.
In addition to the general requirements detailed in the AIP, Civil
Aviation Regulation (CAR) 138 requires pilots to comply with any
specific requirements detailed in aircraft and rotorcraft flight
manuals. Some flight manuals contain specific night flight
limitations. For example, the Transport Canada approved Bell 206B
flight manual states:
'Night flight operation is limited to visual contact flight
conditions. Orientation shall be maintained through visual
reference to ground objects solely as a result of lights on the
ground or adequate celestial illumination.'
The investigation noted that there was no specific night flight
limitation in the Bell 407 flight manual.
Under certain conditions, external visual reference is not
possible while conducting visual operations at night. These include
operating over water or remote areas, in moonless conditions, and
at times when the celestial horizon is obscured by cloud. From the
available information, such conditions probably existed during the
flight from Mackay to Hamilton Island on the night of the
accident.
The investigation to determine the significant factors that
contributed to the Bell 407 accident on 17 October 2003 is
continuing.
