Embraer-Empresa Brasileira De Aeronautica EMB-120 ER , VH-XFZ, 9 km ENE Cairns, (VOR) QLD, 9 November 1999

A Brasilia VH-XFZ was on a visual approach to Cairns from the
south-east and was tracking to left base runway 15. A Citation
VH-PSU departed from runway 15 without a separation standard being
applied by the approach controller between the two aircraft. The
aircraft passed with approximately 500 ft difference in their
altitudes when there was less than 3 NM laterally between them.

The controller could have either coordinated the use of a visual
separation procedure with the aerodrome controller or the crew of
either aircraft, or employed a 1,000 ft vertical separation
standard or a 3 NM radar standard to ensure that the aircraft were
separated.

The investigation revealed that the controller was aware that a
separation standard was required. This was confirmed by the
controller's request to the pilot of XFZ to report seeing PSU that
was shortly to depart. However, subsequent actions limited the
ability of the pilot of XFZ to comply with the request. If this
sighting had been achieved, it would have allowed the transfer of
separation responsibility from the controller to the pilot. This
procedure did not provide separation assurance and was a
"fail-unsafe" procedure as it relied solely on the pilot's ability
to to see the other aircraft and limited the controllers' options
should the pilot be unable to comply.

When the crew of XFZ were unable to sight PSU the controller
then monitored PSU's climb performance and assessed that the
aircraft would not collide. However, vertical separation reduced to
less than the standard when there was no radar standard being
applied.

The use of a radar standard was constrained by the disposition
and intended tracks of the aircraft. In this situation, the Manual
of Air Traffic Services (MATS), 9-2-1, paragraph 19 states that a
procedural separation standard shall be applied. Also, the
controllers actions did not comply with MATS 4-1-1, paragraphs 4-6
which places greater emphasis on traffic planning and conflict
avoidance by controllers instead of conflict resolution. The use of
separation assurance techniques by the controller would have
ensured the separation of the aircraft.