Aviation occurrence briefs

Separation issue involving Aerospatiale AS350, and Robinson R66, 22 km SW of Aldinga (ALA), SA, on 7 January 2018

Status: Completed
Investigation completed


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

On 7 January 2018, a Robinson R66 helicopter departed the north coast of Kangaroo Island on a private flight to Aldinga Airport, South Australia. Upon reaching the mainland, the pilot observed what appeared to be sea fog from the north; however, the pilot then realised it was smoke from a grass fire at Carrickalinga, SA. The pilot advised he was listening on the area frequency and did not hear any notifications regarding a grass fire in the area so continued towards Aldinga at 2,000 ft.

About 10 NM SW of Aldinga Airport as shown in Figure 1, the crew of the Aerospatiale AS350 was conducting and directing fire control services at Carrickalinga and providing periodic transmissions on the Aldinga common traffic advisory frequency (CTAF). The transmissions were for inbound and outbound aircraft in order for them to keep clear of the aircraft conducting fire control below 2,500 ft.

At approximately 1400 Central Daylight-saving Time (CDT), the crew of the AS350 observed the Robinson R66 pass below on an opposite track. The crew of the AS350 turned left and climbed to increase separation. Information from both pilots estimated the distances between the aircraft to be of different clearance heights. The pilot of the R66 advised they were visual with the AS350 at all times. As the R66 passed Carrickalinga, the crew changed to the Aldinga CTAF to provide their 10 NM inbound call, and were notified by the crew of the AS350 of the fire exclusion zone.

Figure 1: Distance from Carrickalinga, SA to Aldinga Airport, SA

Figure 1: Distance from Carrickalinga SA to Aldinga Airport SA

Source: Google Earth, annotated by ATSB.


Class G airspace

Class G airspace is non-controlled airspace. IFR and VFR traffic are permitted without a clearance and there is no separation service provided by air traffic control. Aldinga Airport is a non-controlled aerodrome with a discrete CTAF, which is a different frequency from the surrounding Class G airspace area frequency.

Safety action

As a result of this occurrence, the pilot of the AS350 has advised the ATSB that the incident has been shared among their company to highlight the importance of area frequency scans even when monitoring the local CTAF.

Safety message

This incident highlights the importance of monitoring the area frequency and local CTAF when operating nearby the 10 NM radius to successful identify any potential traffic conflict. As bushfire season has commenced in Australia for 2018 this incident has put attention to when bushfires are observed to try and avoid the area if possible or to ask ATC on the area frequency if there is an exclusion zone in place for fire control operations. Further information is available from ATSB research report: Limitations of the See-and-Avoid Principle.

The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One of the safety concerns relates to safety around non-controlled aerodromes.

The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One of the safety concerns relates to safety around non-controlled aerodromes.

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.

General details
Date: 07 January 2018   Investigation status: Completed  
Time: 1400 CDT    
Location   (show map): 22 km SW of Aldinga    
State: South Australia    
Release Date: 28 March 2018   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer Robinson Helicopter Co  
Aircraft model R66  
Type of operation Private  
Sector Helicopter  
Damage to aircraft Nil  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer Aerospatiale Industries  
Aircraft model AS350  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Nil  
Last update 12 April 2018