The Australian Transport Safety Bureau did not conduct an
investigation into this occurrence. The report produced below is
derived from an investigation conducted by the Department of
Defence-Royal Australian Air Force (RAAF)1.
Reported information
On 20 July 2004, at approximately 1514 central standard time, a
de Havilland Dash 8-200 (Dash 8) was on a visual approach for a
landing on runway 36 at Darwin and was operating under the
instrument flight rules (IFR). At the same time, an Australian Army
Bell 206B-1 (Kiowa) helicopter was departing Darwin and was
operating under the visual flight rules (VFR). The helicopter crew
had been cleared to depart the Darwin control zone via Wickham
Point. Wickham Point was a visual fix located approximately 3.5 NM
south of the threshold of runway 36. According to the RAAF report,
the two aircraft came within 2.6 NM of each other when there was
500 ft vertically between them. There was an infringement of
separation standards.
The RAAF, as the airspace administering authority, was
responsible for the provision of air traffic control services at
Darwin. Local 'low level helicopter release procedures' authorised
the aerodrome controller (ADC) to depart VFR helicopters not above
1,000 ft, tracking direct to one of six visual fixes around the
Darwin control zone, whilst separating the VFR helicopter from all
traffic operating under the IFR.
According to those procedures the approach controller became
aware of a departing helicopter once the aircraft taxied and the
surface movement controller entered the aircraft details into the
automated air traffic control system in use at Darwin. The approach
controller would again be alerted to the departing helicopter when
the radar detected the departing aircraft and the aircraft's track
symbol appeared on the radar display. The approach controller was
also required to advise the ADC of any inbound aircraft so that the
ADC could separate a departing helicopter with other relevant
aircraft.
The RAAF report found that:
- the team of controllers that were operating in the control
tower at the time of the occurrence had been controlling for 2.5
hours, in high density and complex traffic levels, and may have
been fatigued - the controllers in both the tower and in approach had
difficulties coordinating with each other due to the high traffic
levels - the approach controller did not receive notification that the
Kiowa was taxying - the approach controller coordinated the inbound Dash 8 with the
ADC when that aircraft had left 2,000 ft on descent and the
helicopter was level at 1,000 ft - the approach controller became aware of the helicopter when
that aircraft's track symbol appeared on his radar display.
1 For further
information on the RAAF report contact The Directorate of Flying
Safety - Australian Defence Force (FS5), Campbell Park Offices,
Canberra ACT 2600.