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

that the level of detail and the type of information provided by reporters varies
between occurrences.
Movement data
It was intended that this report would also compare the prevalence of airspace
separation breakdowns between aircraft at Class D (formerly General Aviation
Aerodrome Procedures (GAAP)) aerodromes where non-towered aerodrome
(CTAF(R)) procedures apply only outside of ATC operating hours, and non-towered
aerodromes where CTAF or CTAF(R) was always used. This was not deemed to be
possible, as a large proportion of traffic at non-towered aerodromes is VFR, and nontowered
procedures using CTAF(R) usually only apply at Class D/GAAP aerodromes
at night when only Night VFR and instrument rules (IFR) flight are permitted. The
clear exception to this is Camden aerodrome, where the ATC service does not operate
during weekdays.
This caused a problem in conducting a traffic mix analysis on movements at Class
D/GAAP aerodromes, and other aerodromes such as Avalon and Newcastle, which
are sometimes not controlled by ATC. While these aerodromes recorded a significant
number of occurrences, the inability to determine the proportion of traffic operating
when the aerodrome was not controlled by ATC during the reporting period prevented
an analysis of occurrences compared to traffic mix.
REPCON and CAIR data
The inherent confidential nature of reports held in the REPCON and CAIR schemes
means that in many cases, information regarding the location, aircraft, or operation
types involved is de-identified. This makes trend comparison with occurrence data
difficult.
The completeness of REPCON and CAIR data is unknown due to the voluntary
nature of reporting. Some reports also share commonalities with, or are duplicates of,
occurrences that have been reported to the ATSB as reportable matters, and were
therefore included in the 709 occurrences analysed.
- 18 -