The Hiller UH-12E helicopter was tracking from Quirindi to Tamworth. The pilot attempted to call Tamworth Tower on both tower frequencies but received no reply. As the helicopter approached the control zone boundary at 15 NM from Tamworth, the pilot called the tower again but received no reply. He then landed the helicopter and called the tower using his mobile telephone, but received only a recorded message.

Suspecting either a problem with his radio or that the tower was not active, the pilot decided to enter the control zone without a clearance, transmitting his position and intentions on the tower radio frequency. He flew the helicopter into the circuit area and crossed runway 12R between one CT4 aircraft that had landed and a second CT4 on final approach. Upon sighting the helicopter, the aerodrome controller broadcast a traffic alert to the five aircraft operating in the circuit.

The pilot landed the helicopter at the base of the tower and shut down. He walked to the tower and called the controller on intercom. He reported that his radio was unserviceable and requested clearance to re-position the helicopter to the general aviation parking area for repair of the radio. The controller refused clearance and asked the pilot to have the radio repaired before flying the helicopter again. The pilot reported that at the time, he informed the controller that he was unfamiliar with Tamworth Aerodrome, but the controller terminated the discussion. The pilot then walked to the general aviation area, crossing two grass runways without authority.

The controller later stated that the time between his initial sighting of the helicopter and its landing at the base of the tower was insufficient to enable him to give a light signal to the helicopter. There was also insufficient time to instruct the CT4 on final approach to go around.

Examination of the helicopter radio revealed that the frequency selector gears had slipped out of mesh and out of position.

The pilot reported that this was his first flight into the Tamworth control zone, and that he had not briefed himself adequately before departing Quirindi. Aeronautical Information Publication ENR 1.1 section 9.2 (dated 10 August 2000) detailed the requirements for VFR flights entering Classes C or D airspace. Paragraph 9.2.1 stated:

"Before reaching the boundary of classes C or D airspace, the pilot must establish two-way communications with ATC on the frequency notified on the chart, in ERSA, or AIP supplement or NOTAM, and obtain a clearance."

Enroute Supplement Australia EMERG 2 detailed the procedure for flights OCTA under VFR experiencing communications failure, and stated:

Stay in VMC
Broadcast intentions (assume transmitter is operating and prefix calls with "Transmitting blind") Remain VFR and land at the nearest suitable non-MBZ aerodrome. Report arrival to ATS if on SARTIME or reporting schedules. Search and Rescue telephone number 1800 815 207.