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

1.3 Scope
This report focused only on occurrences at/near non-towered aerodromes which were
deemed to be related to airspace use, separation, communication or procedures when
those aerodromes were under CTAF/CTAF(R), or MBZ procedures.
The reporting period for occurrences in this report was 1 January 2003 to 31
December 2008. The intention of selecting this period was to analyse occurrences at
non-towered aerodromes across an ample time prior to and after the procedural and
airspace changes introduced by NAS 2C on 24 November 2005 at all non-towered
aerodromes in Australia. Readers should note that this 6-year period was prior to the 3
June 2010 changes to non-towered aerodrome procedures.
Specific occurrence types that were reviewed were:
• airspace occurrences related to:
– aircraft separation (airprox, mid-air collision, traffic collision and avoidance
system (TCAS/ACAS) alerts and other separation-related events)
– ATC procedural errors (information errors, failure to pass traffic)
– failures to comply (FTC) (published instructions for VFR/IFR traffic, verbal
instructions for enroute IFR traffic)
• operational occurrences related to:
– communications (air-to-ground, air-to-air, callsign confusion, radio or
transponder-related and other events)
– navigation or flight preparation (lost or unsure of position, pre-flight planning,
VFR flight into instrument flight conditions (IMC) and other events)
– ground operations (collisions on ground, groundprox 9 )
– runway events (incursions, depart/approach/landing on wrong runway)
Consequential events (such as missed approaches, go-arounds and diversions) were
also considered.
Only occurrences that occurred within 15 NM (27.8 km) from a non-towered
aerodrome were considered in this report’s analysis. While the current CAR definition
for ‘in the vicinity of’ a non-towered aerodrome includes a 10 NM radius, the higher
value was used as the reporting period for this study contained both occurrences that
occurred in MBZ/CTAF areas (pre-NAS 2C, where the MBZ airspace boundary was
set as 15 NM) and under post-NAS 2C non-towered aerodrome procedures, where
CTAF (and formerly CTAF(R)) is used and a 10 NM vicinity limit applies in place of
a bounded airspace area.
9 A groundprox is defined by the ATSB as an occurrence requiring immediate braking action by the
pilot, flight crew, or vehicle driver in order to avoid a collision (ATSB, 2010a).
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