| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
At about 0945 Eastern Standard Time on 20 September 2020, the pilot of a Robinson Helicopter Company R44 was conducting a 15-minute scenic flight from Archerfield Airport, Queensland with two passengers on board. The route flown departed Archerfield to the east, then headed north past the Brisbane CBD (B in Figure 1) before tracking south via Mount Coot-tha (A in Figure 1). The departure used a helicopter-only procedure known as a ‘University departure’ via the ‘Univat VFR Route’ (Figure 1) to remain clear of surrounding controlled airspace.
The R44 departed Archerfield at 1,000 ft and after passing the Brisbane CBD, climbed to 1,500 ft until reaching Mount Coot-tha. At Mount Coot-tha, the pilot conducted a descent to 1,000 ft as required by the Univat VFR route to remain clear of controlled airspace, and broadcast on the area frequency.
At about 1000, an Aerospatiale Industries AS350 departed Archerfield Airport for Mount Coot-tha via the published northern departure procedure. This procedure required aircraft to maintain 1,000 ft until reaching a VFR tracking point with the radio selected to the Archerfield Tower frequency until the control zone boundary. On reaching the boundary, the AS350 pilot conducted a slow climb and gentle turn towards Mount Coot-tha. Shortly after the AS350 commenced the turn, pilot of both helicopters reported seeing the other helicopter in close proximity on a converging track and immediately manoeuvred to avoid a collision.
The AS350 pilot reported, as the aircraft passed each other, Brisbane Centre made a broadcast on area frequency advising of a collision risk between two aircraft at Mount Coot-tha to which the pilot replied, confirming they were clear. Both pilots reported not hearing any calls from the other helicopter pilot and were probably on different frequencies prior to the proximity event.
Both helicopters were fitted with ADS-B traffic warning systems reported as serviceable and switched on, but neither pilot received a traffic alert. The pilots estimated the helicopters passed 50 m apart.
Figure 1: Archerfield arrivals and departures
Source: Google Earth, annotated by ATSB
Guidance material
The Civil Aviation Safety Authority (CASA) Visual Pilot Guides and online program, OnTrack, which provided recommended procedures for pilots operating in busy metropolitan airspace, are no longer available. However, CASA is developing large wall charts designed for flying schools in metropolitan areas, including Brisbane.
Airservices Australia safety publication Tips for flying at Archerfield details operating procedures and considerations when planning a flight. This supplements information provided in the Aeronautical Information Publication – En Route Supplement Australia section Archerfield – Flight procedures.
Safety action
As a result of this occurrence, the R44 operator has advised the ATSB that it has commenced a trial to make additional calls approaching outbound waypoints and to reverse the flight path flown on the scenic flights. This will keep their helicopters to the east of traffic tracking north to Mount Coot-tha.
Safety message
Archerfield is a busy control zone between Brisbane civil class C and Amberley military class C airspace. Published flight procedures facilitate aircraft movements and assist air traffic control co-ordinate local traffic.
Following a national review of class D airspace in 2010, aircraft operating under visual flight rules no longer need to use published inbound reporting points, provided two-way communication is established with the Tower prior to entry to the control zone. This allows aircraft to approach from any direction, which may result in conflict with traffic adhering to the recommended procedures. When there are multiple frequencies in use and traffic are operating close to control zone boundaries, this increases the likelihood of pilots being unaware of conflicting traffic.
The ATSB recommends pilots operate in accordance with published procedures wherever possible.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.