Cessna Aircraft Company 404, VH-ANM

The Australian Transport Safety Bureau did not conduct an
investigation into this occurrence. The report produced below is
derived from an investigation report produced by the Department of
Defence-Royal Australian Air Force (RAAF)1 which was the administering authority for
the Darwin Control Zone.

Reported information

On 21 July 2004, at 0955 central standard time, a Cessna
Aircraft Company 206 (C206) departed Darwin for Croker Island, NT.
The aircraft was being operated under the visual flight rules
(VFR). Another aircraft, a Cessna Aircraft Company 210 (C210)
departed Darwin at 0956 for Snake Bay, NT, and was also being
operated under the VFR. A third aircraft, a Cessna Aircraft Company
404 (C404) departed Darwin at 0958 for Croker Island. That aircraft
was being operated under the instrument flight rules (IFR). All
three aircraft were instructed by the aerodrome controller (ADC) to
fly a heading of 060 degrees after take off.

The RAAF investigation report found that the pilot of the C404
had been instructed to sight and maintain visual separation with
the C210. However, the C404 also caught up with and eventually
overtook, the C206. Neither the pilot of the C206 nor the pilot of
the C404 received traffic information on the other aircraft, and
neither pilot was assigned the responsibility for separation with
the other aircraft. According to the RAAF investigation report, the
C404 passed within 0.2 NM of the C206 while both aircraft were at
the same altitude. There was an infringement of separation
standards.

The Manual of Air Traffic Services (MATS) section 4.5.1.4
authorised the assignment of responsibility for separation to the
pilot of one aircraft if that pilot reported 'sighting the other
aircraft and is instructed to maintain visual separation with, or
to follow that aircraft'. The MATS Section 4.5.1.2 also stated
that, when applying visual separation, 'controllers shall consider
aircraft performance characteristics, particularly in relation to
faster following aircraft'.

Darwin was operating on auto-release procedures at the time of
the occurrence. The MATS Part 10, section 1 defined auto release as
a procedure whereby the ADC must ensure that the spacing between
successive departing aircraft is sufficient to enable the
Departures controller to establish and maintain the required
separation minima. In this occurrence, the responsibility for
establishing and maintaining the required separation minima between
the C210 and the C404 had been assigned to the pilot of the C404.
The ADC did not ensure that the departures controller could
establish and maintain separation between the C206 and the C404,
and the responsibility for establishing and maintaining separation
had not been assigned to either pilot.

1 For further information on the RAAF report
contact The Directorate of Flying Safety - Australian Defence Force
(FS5), Campbell Park Offices, Canberra ACT 2600.