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

6.3 Other alerted ‘see-and-avoid’ tools
6.3.1 Traffic Collision Avoidance System (TCAS/ACAS)
There were 87 occurrences where flight crew were alerted about a potential conflict
with another aircraft through a TCAS/ACAS traffic advisory (TA) or resolution
advisory (RA). 29 Of these TCAS alerts, at least 73 were RAs, and 18 of these
indicated that an airprox had occurred.
This does not necessarily indicate that the flight crews/pilots of each aircraft were not
aware of each others’ presence and position, either visually, by radio, and/or by
proximate aircraft paints on the TCAS/ACAS plan position display. There were,
however, 52 occurrences where the other aircraft was not visually sighted or in
communication prior to a TCAS/ACAS TA or RA being issued to at least one of the
flight crews/pilots.
Due to the airspace design around Avalon Aerodrome, there were a large number of
TCAS/ACAS alert events that occurred on aircraft operating on approach or circuiting
Avalon where traffic advisories were provided on aircraft transiting in the vicinity of
Avalon, or conducting circuits at Point Cook Aerodrome.
6.3.2 Air-ground radio services
Air-ground radio services exist at some non-towered aerodromes to provide further
operational information to pilots, and to support broadcasts on the CTAF. Certified
Air-Ground Radio Services (CA/GRS), Universal Communications (UNICOM) and
Flight Information Service operators can provide the following information at some
aerodromes via broadcasts on the CTAF:
• confirmation of the CTAF radio frequency allocation being used
• estimated times of arrival and departure for aircraft operating to/from that
aerodrome
• aerodrome and runway information
• unscheduled landings by aircraft
• general weather reports
• advice to emergency services regarding aircraft in need of assistance
• fuel requirements
• maintenance and servicing of aircraft, including the ordering of urgently required
parts and materials
• passenger requirements.
In addition, CA/GRS and Flight Information Service are also authorised by CASA to
provide basic traffic information to pilots. These air-ground radio services exist only
as a tool to help enhance pilots’ situational awareness, and are not a traffic separation
service. Unlike CA/GRS, UNICOMs are not designed to provide any traffic
information. In both services, information is provided on pilot request. The
29 The ATSB only records TCAS TAs and RAs as safety occurrences if they occurred as the result of
another safety issue (such as an airprox, reduced separation between aircraft, missed approach, or a
communication breakdown).
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