Infringement of separation standards at Darwin airport

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.