An ATSB report has found that a recent airspace incident was
both an 'airprox' and a 'serious incident' and that a Brasilia and
a Partenavia aircraft passed about 40 m horizontally at the same
altitude from each other.
The flight crew of the instrument flight rules (IFR) Brasilia
was on descent through 9,500 ft from Darwin to Kununurra Airport on
airway J72 in visual meteorological conditions (VMC). The flight
was a scheduled Regular Public Transport (RPT) service. The pilot
of a visual flight rules (VFR) Partenavia was tracking in the
opposite direction from overhead Kununurra to Darwin at 9,500 ft.
The pilots were operating outside controlled airspace and beyond
air traffic control radar coverage.
Approximately 50 NM north-north-east of Kununurra at FL220, the
Brasilia co-pilot broadcast the aircraft's position on the area
frequency 122.4 MHz and that the aircraft was on descent to
Kununurra.
The Partenavia pilot broadcast the aircraft's position overhead
Kununurra on the mandatory broadcast zone (MBZ) frequency 127.0 MHz
and reported tracking 023 for Darwin at 9,500 ft. He was operating
outside the vertical and lateral confines of the MBZ and did not
receive a response.
Approximately 30 NM north of Kununurra, as the Brasilia was
descending through 9,500 ft, the pilot in command briefly saw a
Partenavia, in his peripheral vision, fly past the Brasilia's left
wing. Visibility at the time was reported as very good. The
Brasilia crew estimated that the distance between the aircraft was
40 m, at the same altitude. There was insufficient time to take
evasive action. The Partenavia pilot did not see the Brasilia.
The ATSB investigation found that had the Partenavia pilot
selected the appropriate area frequency for the Kununurra region,
he may have been alerted to the inbound Brasilia. In addition, some
of the safety issues that pilots need to consider are the dangers
of assuming that higher performance aircraft are TCAS (traffic
alert and collision avoidance system) equipped and that crews can
rely on it as a primary separation tool.
The airspace in which the incident occurred was not restructured
as part of the National Airspace System (NAS).
The full investigation report (200402626) is available from the
Bureau's
website, or from the Bureau on request.
Media Contact: 1800 020 616
