Air traffic control (ATC) local procedures need to be unambiguous and encompass all possible operational circumstances. That is the safety message arising from the loss of separation between a Cessna 402C and a Cessna C210 that occurred 6 km north of Cairns, Queensland on 23 November 2011. Effective radar navigation guidance is also important when positioning an aircraft for an approach.
The C402 was conducting an instrument landing system (ILS) approach for runway 15 at Cairns airport and was 1.8 NM (3.3 km) from the airport when the pilot initiated a missed approach from a height of 1,000 feet in instrument meteorological conditions. At the time, the C210 was on the same ILS approach and was 6.4 NM (11.9 km) behind the C402. About 1 minute after the pilot turned left to establish the aircraft on the missed approach track, the distance between the two aircraft reduced below the required ATC separation standard.
Airservices has amended the local procedure to assist with the clarity and intent...
The ATSB identified that a local ATC procedure published, in part, to assist ATC in separation management during a missed approach event, was not clear and was subject to varying interpretations. This resulted in the spacing between the aircraft being closer than intended when the pilot of the C402 commenced the missed approach. The local procedure did not fully consider all operational aspects that could lead a pilot to initiate a missed approach in instrument meteorological conditions above the procedure-defined minimum cloud base height.
In response to this occurrence, Airservices has amended the local procedure to assist with the clarity and intent and to enforce minimum flow (distance) spacing, and has updated controller missed approach procedures refresher training. The updated training will increase controller awareness of separation assurance issues relating to consecutive approaches and ensure that controllers give due consideration to the broad range of aircraft types using straight-in approaches.
Read the report: Loss of separation between VH-TFK and VH-PDP, 6 km north of Cairns, Queensland, on 23 November 2011