Safety in the vicinity of non-towered aerodromes - Australian ...

The then Department of Transport and Regional Services identified the following key
changes introduced by NAS (a summary of airspace classes is provided in Appendix
A):
• some uncontrolled airspace (Class G) became controlled airspace (Class E)
• improved services for aircraft operating under visual flight rules (VFR) in radar
Class G and E airspace, such as access to radar based information services
• lowering the base of Class A airspace to 18,000 ft in areas with radar coverage
• a proportion of en route Class C airspace was changed to Class E
• an expansion of mandatory transponder carriage to include all aircraft operating
above 10,000 ft
• the introduction of standardised operating procedures at all non-towered
aerodromes (Department of Transport and Regional Services, 2007a; 2007b).
In July 2007, CASA established the Office of Airspace Regulation (OAR) to regulate
airspace under the Civil Aviation Act 1988, Airspace Act 2007, and Airspace
Regulations 2007. The OAR has responsibility for the regulation of airspace
consistent with the Australian Airspace Policy Statement.
In relation to non-towered aerodrome operations, the OAR is involved in activities
such as:
• facilitating the reduction of Common Traffic Advisory Frequency congestion and
interference problems in consultation with state-based Regional Airspace and
Procedures Advisory Committees (RAPACs); and
• conducting aeronautical studies of a diverse range of aerodrome types to identify
risks related to airspace or operations, their likelihood and consequences, and ways
in which they can be best managed.
1.1.5 Common Traffic Advisory Frequency (CTAF/CTAF(R)) and the
replacement of Mandatory Broadcast Zones (MBZs)
Prior to the introduction of NAS 2C on 24 November 2005, three different sets of
rules and procedures applied at Australian aerodromes in Class G airspace 7 . The NAS
replaced these with a single, North American-style CTAF procedure, with some
changes to enhance suitability for Australian operations.
A CTAF is the common radio frequency used for air-to-air and air-to-ground
communication in the vicinity of non-towered aerodromes in Australia, the United
States and Canada. The purpose of the CTAF is for pilots to have a common
frequency to communicate and establish situational awareness, and if required,
arrange mutual separation between their aircraft and other nearby traffic or aviation
activities (such as parachute drops, ballooning, or gliding). While some aerodromes
have specific CTAF (as noted on aeronautical charts and in the ERSA), the most
commonly used CTAF in Australia is 126.7 MHz.
As a result of the NAS 2C introduction, MBZs and defined CTAFs were abolished,
and replaced with radio-alerted procedures, known as CTAF(R). While MBZs were
conceptually similar to the current non-towered aerodrome procedures, it has been
7
In Australia, non-controlled airspace is classified as Class G airspace. Appendix A provides a
summary of airspace classification in Australia.
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