Background
VH-SWP was operating under a standard company flight plan for the route Bankstown-Tamworth-Armidale-Glen Innes-Inverell and return. The flight plan indicated the flight would be conducted in accordance with IFR procedures, and the classification was non-scheduled commercial air transport, though the aircraft operated to a company schedule. Departure and flight times for each route segment were noted.
Flight Progress
The aircraft departed Bankstown at approximately 0640 and proceeded as planned to Inverell, where the pilot rested until the afternoon return journey. The schedule required an Armidale departure at 1721. At 1723, the pilot reported to Sydney Flight Service that he was departing Armidale for Tamworth, with a planned flight time of 17 minutes.
Initially, the flight-planned altitude for the sector was 6,000 ft, but the pilot could not climb immediately due to a slower aircraft that had departed Armidale for Tamworth two minutes earlier and was climbing to that altitude. Additionally, opposite direction traffic was at 7,000 ft. The next suitable altitude was 8,000 ft, but separation from the other IFR aircraft had to be established. The published IFR lowest safe altitude was 5,400 ft. The pilot elected to remain at 4,500 ft in visual meteorological conditions (VMC).
At 1727, the pilot requested an airways clearance from Tamworth Tower. ATC issued a clearance to track direct to Tamworth at 4,500 ft visually.
Final Approach
At approximately 1732, the pilot requested a descent clearance. He was cleared for a visual approach with a clearance limit of 5 NM by DME from Tamworth, and was requested to report at 8 DME. The pilot acknowledged and reported leaving 4,500 ft on descent.
Transmissions from ATC to the pilot less than two minutes later were not answered. The aircraft was not being monitored by radar, nor was this required.
Search and Wreckage
At about 1740, reports were received by police and ATC of an explosion and possible aircraft accident near the mountain range 8 NM northeast of Tamworth Airport. The wreckage was discovered at about 2115 by searchers on the mountain range.
Soon after the aircraft was reported missing, a search aircraft pilot with extensive local flying experience reported to ATC that the top of the range (where the accident occurred) was obscured by cloud, and that there was very low cloud in the valley nearby.