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Frequency congestion on the Port Augusta (YPAG) Common Traffic Advisory Frequency (CTAF

Reporter's deidentified concern

The reporter states that the CTAF is shared with the Flinders Ranges, Renmark area, Kadina, Port Pirie and numerous other areas, which results in considerable congestion and interference.

There is often numerous high capacity/high performance aircraft needing to communicate clearly on this frequency, which is often difficult in itself while also communicating with Centre, but to add numerous distant aircraft conducting training and scenic flights, on the same frequency is a disaster waiting to happen. The reporter states that in a one week period in and around YPAG, they recorded six occasions where they had difficulty communicating with other aircraft to establish separation, due to CTAF interference/congestion.

The reporter advises that these concerns have been reported to the regulator via their employer approximately 18 months ago and as a result, revisions of the airspace/charts has been discussed at various levels including RAPAC; however, to date there has been no amendments to the CTAF.

The reporter is deeply concerned at the time it is taking to make these changes and is concerned for the safety of the travelling public.

Named party's response

CASA response:

Information presented at the South Australian regional airspace and procedures advisory committee (RAPAC) identified several aerodromes located within the Spencer Gulf area that cause pilots some concern due to overlapping instrument flight procedures and the different frequencies associated with each aerodrome. The consensus of the SA RAPAC was for the Office of Airspace Review (OAR) to further investigate this matter. The OAR reviewed the information and engaged with various stakeholders operating in the Spencer Gulf area on the proposal to establish a Broadcast Area using a CTAF. The proposed change was considered and supported to proceed by the South Australian RAPAC in November 2019. The change has since been subject to further consultation, including with Airservices Australia. This process has now been completed and CASA is advised that the anticipated implementation date for the change is June 2021.

The REPCON raised concerns that radio congestion and interference at Port Augusta (YPAG) was due to the aerodrome being on the same multicom frequency (126.7) as multiple other aerodromes, including Port Pirie.

While the creation of the Spencer Gulf Broadcast Area on 126.9 has removed some aerodromes from the same frequency as YPAG; Port Pirie remains on the same frequency. In addition, a relatively busy aerodrome in Whyalla, which was previously on a separate frequency to YPAG, is now also on the same CTAF as YPAG and Port Pirie.

Occurrence brief AB-2021-017 regarding a near collision of a high capacity RPT highlights that radio congestion at YPAG, from Port Pirie, is a concern.

The ATSB notes that the creation of the Spencer Gulf CTAF would not have mitigated any risks relating to congestion/interference encountered in the above occurrence, nor does it appear to address the concerns raised in the initial REPCON.

The ATSB will continue to monitor any reports of congestion/interference at Port Augusta and Whyalla over the following months and welcomes any additional information/outcomes of the next scheduled review of the airspace.