Frequency use at low level in Class G airspace - (CD 1802AS)

Closed 14 May 2018

Opened 27 Apr 2018

Results updated 18 Oct 2018

This consultation proposed the use of 126.7 MHz specifically in the circuit area of uncharted aerodromes, instead of the current recommendation to use the area frequency.  As CASA had already received substantial general feedback on radio frequency use in low level airspace, this consultation asked for feedback as to whether there would be any practical implementation issues, or any safety issues raised by the proposal.

The results

CASA received 298 responses. Thirty-one responses were submitted on behalf of an organisation with 29 providing CASA with permission to publish. The organisations that agreed to the publication of their response are listed in Appendix A of the Summary of Consultation (see ‘Files’ below).

Overall, 173 (58 per cent) of respondents did not identify issues with practical implementation or any additional risks with the proposal.

 Of the 42 per cent of respondents that did provide feedback, the main issues raised were:

  • confusion relating to inbound call procedures when applying the proposed frequency boundary for 126.7 MHz in the circuit area of uncharted aerodromes
  • radio congestion/workload issues with frequency changes, especially for sport and recreational aircraft
  • requests for uncharted aerodromes to be added to the aeronautical charts
  • situational awareness concerns with two frequencies in use in the same airspace
  • requests for a comprehensive education and awareness campaign to explain the correct radio procedures.

Future direction

As a result of the feedback received from the consultation for ‘Frequency use in Class G’, CASA has determined not to implement the 20 NM/below 5,000 ft AMSL proposal or the use of MULTICOM 126.7 in the circuit area of uncharted aerodromes. The Aeronautical Information Publication (AIP) will be simplified and less prescriptive about the frequency to use at those aerodromes that are uncharted.

To ensure the feedback from this consultation is addressed, CASA has taken action to:

  • simplify the content with the AIP relating to the selection of radio frequency when operating in Class G airspace and at non-controlled aerodromes.
  • develop and deliver education materials to reinforce consistent application of radio procedures
  • increase the number of aerodromes displayed on the visual aeronautical charts (WAC, VTC & VNC) to provide better situational awareness for pilots and for ease of selecting the most appropriate frequency.

The amendment to AIP relating to radio frequency use will be incorporated in AIP at the AIRAC cycle effective 28 February 2019. Furthermore, Civil Aviation Advisory Publication (CAAP) 166-01 will require minor amendments to support the AIP amendments. We anticipate consulting publicly on that amendment during November 2018.  

CASA has already progressed with the development of educational materials that include booklets, updates to the Visual Flight Rule Guide (VFRG) and CASA Flight Planning Kit, e-learning modules and incorporation into Aviation Safety Seminars. This will be a sustained campaign to ensure lasting pilot awareness and consistent application of the recommended procedures.

CASA continues to work with Airservices Australia to incorporate all aerodromes that have been allocated an ICAO four-letter code (e.g. YADY) onto WAC, VNC and VTC charting products whilst considering chart clutter. At time of publishing this document, it is planned that will be progressively rolled out from May 2019.



Published responses

View submitted responses where consent has been given to publish the response.


CASA invites all pilots who operate at low level in Class G airspace to comment on a new proposal that would change the guidance for radio frequency use at uncharted aerodromes.  

Responses to the previous consultation, Frequency use at low level in Class G airspace (NPRM 1712AS) identified a number of critical issues that required further consideration. Most notably, these were around the extent of overlapping frequencies that would be created by the proposal to expand CTAFs, and radio carriage and workload implications for hang gliders and paragliders.

As a result, CASA did not implement the proposal.

Proposal – use MULTICOM 126.7 in the circuit area of uncharted aerodromes

Noting there was some support for the previous proposal (NPRM 1712AS) that expanded CTAFs to 20 nm radius at locations where passenger transport operations occur and majority support for using MULTICOM (126.7 MHz) in low level Class G airspace, CASA conducted a risk assessment which examined a number of scenarios.

These scenarios included whether it was feasible to either implement 126.7 MHz below A050, but only retain 20 nm CTAFs for aerodromes with regular passenger transport (RPT) operations, OR implement 126.7 MHz below A050 with no change to existing CTAF dimensions. Both of these scenarios resulted in a level of risk that CASA was unable to support.

Therefore, to deliver on the industry preference whilst maintaining an acceptable level of risk, CASA is proposing a solution that would maintain the status quo but, in addition, allow the use of 126.7 MHz in the circuit area of uncharted aerodromes.

This solution would see local (uncharted) aerodrome traffic no longer broadcasting on ATC frequencies. CASA acknowledges this solution introduces the risk of transiting aircraft being unaware of the existence of an aerodrome due to not being on an aeronautical chart. However, CASA considers the risk to be low with the appropriate controls already in place. These controls include, but are not limited to:

  • high radio carriage and usage within the flying community
  • capacity for pilots to monitor two radio frequencies simultaneously
  • IFR aircraft operating at or above lowest safe altitudes and at IFR cruising levels and therefore above circuit height
  • low traffic numbers at (most) non-charted airfields
  • local knowledge
  • the use of ‘see and avoid’.

No rule change would be required to implement this proposal. Small updates would be made to the relevant guidance in CAAP 166-1 and the AIP.

These proposed updates would be similar to information contained in the pre-2013 AIP, but with the important clarification that 126.7 MHz would be used ‘in the circuit area’ at the aerodrome rather than ‘in the vicinity’ of the aerodrome. The ‘circuit area’ would be defined as within a 3 nm radius of the aerodrome and extending from the surface to 1,500 feet above ground level vertically.

Why your views matter

CASA would like to ensure all pilots have the opportunity to provide comment on this proposed solution. We are particularly keen to hear if there are any other safety concerns related to the implementation of these proposed changes to the guidance. 

Next steps

Based on the outcome of consultation over the past couple of years, CASA proposes to take the following action on the issue of radio frequency use:

  • implement the use of 126.7MHz in the circuit area of uncharted aerodromes
  • recommend that ‘busy’, currently uncharted, aerodromes be published on aeronautical charts
  • ensure that all aerodromes in the Airservices Australia database will be published on aeronautical charts unless verified that they no longer exist or where not possible due to chart clutter to reduce the risk of uncharted aerodromes
  • develop education and training material in collaboration with industry to ensure consistency and common understanding of radio procedures.

CASA thanks all industry members who have been involved in this conversation. Consultation with industry groups along with public consultation has enabled us to explore many options to implement 126.7 MHz, and identify and capture practical issues in airspace across Australia.


  • Air operators


  • Airspace and infrastructure