Separation issue involving a British Aerospace PLC BAe 146-200, VH-JJU and Cessna 207, VH-UBX, 24 km west-south-west of Kununurra Aerodrome, Western Australia, on 10 December 1996

The BAe146 was inbound to Kununurra from Curtin and the crew had been listening on both the area and the MBZ frequencies. They heard the pilot of the C207 make contact with Perth and discuss SARTIME arrangements and give his destination as Broome. This information indicated the C207 might be conflicting traffic for their arrival. They assumed the C207 was still on the ground at that time. As nothing further was heard from the pilot of the C207, the crew of the BAe146 made several attempts to contact him. When contact was established the C207 was 12 NM from Kununurra on the 242-degree radial at 5,500 ft. The BAe146 was 14 NM from Kununurra on the 250-degree radial at 3,800 ft, on descent.

The pilot of the C207 reported that his aircraft was fitted with one VHF set. After making his departure report on the MBZ frequency he changed to the area frequency and became engaged in a discussion with Perth flight service about his SARTIME. The discussion took longer than expected and during that time he could not hear any transmissions from the BAe146 on the MBZ frequency. When he changed back to the MBZ frequency he heard the transmission from the BAe146, and he answered immediately. He had tracked south of the Kununurra - Broome track to remain clear of cloud. He does not believe he came close to the BAe146.

It is likely that the discussion between the pilot of the C207 and Perth flight service, which the crew of the BAe146 assumed had taken place whilst the C207 was still on the ground, was the one that occurred after the C207 had departed. Consequently, the BAe146 crew did not hear the taxi and departure transmissions that preceded that discussion. The fitment of only one VHF set prevented the pilot of the C207 from adequately monitoring the MBZ frequency and, as a result, separation between the two aircraft could not be arranged in a timely fashion.