At Sydney, the aircraft had been released for service, prior to departure for Bangkok, with the number three engine fire detection 'B' loop inoperative, in accordance with the provisions of the minimum equipment list. The remaining 'A' loop would be used for fire detection and warning for the engine. The aircraft operated normally to Bangkok, where a transit service was performed before the next sector to Rome.

The subsequent take-off was rejected at 140 knots when the fire warning for number three engine activated. The aircraft returned to the gate where eleven of the sixteen mainwheels deflated due to overheating. The mainwheels were changed. Rectification of the fire warning problem consisted of repairing a broken wire at the 'B' fire detection loop connector, adjacent to number three engine starter motor. Both 'A' and 'B' loops then tested normally.

As the aircraft was rotated during the next take-off the number three engine fire warning activated again. The crew carried out the fire warning actions and shut down the engine. Fuel was jettisoned to bring the aircraft to maximum landing weight, prior to returning to Bangkok. An inspection of the engine revealed two holes burnt in the combustion case adjacent to the fire detection loops. The holes allowed hot gasses to escape and activate the fire warning system.

Investigation of the incident by the operator has resulted in a change to company procedures. Any rectification for a fire warning defect will now require a ten minute minimum high power ground run to verify the integrity of the engine. In addition, the inspection intervals for combustion cases have also been reduced.

The captain of VH-KDO gave taxiing calls on both MBZ and FS frequencies, advising they were taxiing for runway 09.  Shortly before commencing their take-off roll, the crew of KDO heard the pilot of VH-PRN advise he was taxiing for runway 36.  As they commenced their take-off roll, the captain made a call to "all stations Mildura and PRN - KDO is rolling runway 09".  The pilot of PRN acknowledged that call. After they had passed V1 and rotated, they saw PRN becoming airborne from runway 36.  The crew of KDO took avoiding action, passing approximately 300 ft above and 100 to 150 m behind PRN.

The pilot of PRN reported later that he had misinterpreted the "rolling" call from KDO, and believed when he heard that call, KDO was in fact commencing to taxi.  At Mildura there are aerodrome buildings located between the thresholds of runways 36 and 09 so that a pilot in an aircraft at one threshold cannot see an aircraft at the other threshold nor for the initial part of the take-off run.  There is a notice to this effect in the Enroute Supplement.

Circumstances

Both aircraft were outbound from Cairns on the same track and on climb to FL 330. VH-TJD was about 9 NM behind VH-CZI. When CZI was transferred to Cairns Arrivals frequency, the crew advised that the aircraft would be cruising at reduced Mach 0.65. The controller, who had not previously experienced such a situation, did not associate this information as having any influence on the climb performance of the aircraft. He believed that because the aircraft were approximately co-speed, separation was assured throughout the climb. As CZI climbed above about FL250, the Mach Number restriction to that aircraft began to take effect and a groundspeed differential developed between it and TJD. There was other traffic in the area at the time, with the labels for these aircraft reducing the information available to the controller concerning the separation of CZI and TJD.

The aircraft were transferred to the next sector (7V) when CZI was passing FL 280. By this time, the groundspeed of TJD was 425 kts, and of CZI, 368 kts. Horizontal separation was about 6 NM and reducing. The sector 7V controller instructed CZI to maintain FL280. The crew advised that they had passed that level but would return to it. TJD then reported leaving FL297.

Examination of the recorded radar data revealed that radar separation reduced to a minimum of 4.8 NM. At the time, CZI was at FL287 and TJD at FL297. The required separation standard was 5 NM laterally and 1,000 ft vertically.

Information from the Cairns Arrivals controller, and other experienced controllers, indicated that the effect of reduced Mach No climbs on aircraft performance was not fully appreciated. Local management reported that controllers had been rebriefed on this issue.

The pilot reported that he was engaged in moving cattle on a flooded property. On board the helicopter with the pilot was the property owner. While hovering at about 30-40 feet behind some cattle, the pilot's attention was diverted momentarily allowing the engine and main rotor RPM to decay. He was unable to regain rotor RPM and elected to attempt a landing onto a nearby dry patch of ground. In turning the helicopter towards the dry ground, the pilot inadvertently turned down wind, overpitching the main rotor blades. During the ensuing deep flare to land, the tail rotor contacted the water and the main rotor blades severed the tail boom. The helicopter then settled into the water and rolled over. Both the pilot and passenger were able to exit the helicopter safely.

The pilot reported that whilst flying at FL310 clear of cloud and avoiding a large build up, the aircraft was struck by lightning. The pilot was of the opinion that there was one strike on the left-wing tip and one near miss. There was a large flash, and a loud bang followed with an ozone smell but no smoke. The avionics and electrical systems were not affected. The flight continued to Perth.

After landing, the aircraft was inspected by ground staff who found damaged elevators and propellers.

The pilot reported that he was carrying out an inspection of the area to be treated when the engine made an unusual noise and began to vibrate. The pilot immediately turned the aircraft for a return to the departure airstrip and when power was reduced the engine began to run roughly. The engine then began to loose power and the pilot had to pump the throttle to keep the engine going. The pilot said he reached the end of the strip and on touchdown the right wheel struck soft ground. The right wingtip then struck the ground, and the aircraft nosed over. The pilot was suspended upside down by the seat harness and was drenched by organophosphate leaking from the hopper. The pilot could not open the door due to the cockpit roof being buried in mud. He was then forced to kick the window out to evacuate, and lost portion of his ring finger and broke bones in his left hand during his egress.

After selecting the landing gear down prior to landing, the gear unsafe warning light remained illuminated and there was no down and locked indication for the left main landing gear. After consultation with company engineering personnel, the pilot made a low flypast to enable an assessment from the ground as to whether the landing gear was down and locked. The pilot was advised that from the ground the landing gear appeared to be down and locked. Shortly after landing the left main landing gear collapsed.

An inspection after the accident failed to determine the reason for the collapse.

The pilot of VH-KWG called Essendon tower saying words to the effect that "he was just down from Mildura, a bit short on fuel and requesting an approach to the airstrip on the left". The Essendon tower controller checked his radar screen and noted a primary return on a left base for runway 16 at Melbourne. The return was confirmed as being KWG. At the same time a B727, VH-ANB, was joining final for runway 16 approximately three miles behind KWG. The Essendon tower controller coordinated with the Melbourne tower controller to divert ANB to avoid a serious conflict on final approach. KWG was retained on Essendon tower frequency and cleared to land on runway 16 at Melbourne.

Investigation revealed that the pilot was from another state and not familiar with the area. He had planned a flight from Mildura to Wangaratta. He was using a portable GPS but its battery went flat during the flight and its DC power supply system was not working. Having lost GPS information, he tuned the aircraft's ADF to Wangaratta but did not check the morse code identifier. Furthermore, there were isolated thunderstorms in the area and the pilot had been diverting around cloud en route. He did not have an Enroute Supplement or an ERC Low or a WAC chart. He was carrying an ONC chart. He reported that he followed the ADF needle until he saw Melbourne Airport where he finally landed.

A pilot/aircraft engineer who later assessed the aircraft for recovery purposes reported that the grass was about 60 cm long. The pilot later advised that when he applied full power for take-off, the manifold pressure gauge was indicating 26 inches and tachometer was indicating 2,600 RPM.

FACTUAL INFORMATION

A Piper Chieftain registered as VH-HVA (HVA) had been flight planned to operate a flight from Maitland to Sydney at 6,000 ft. Another Chieftain registered VH-TXK from the same company was planned to conduct a flight from Gunnedah to Sydney at 7,000 ft. There was approximately 15 degrees between the inbound tracks of the two flights and their respective flight times and estimated time of departures indicated that they would arrive at Sydney at about the same time.

The two aircraft departed and were approaching Sydney when the pilot of HVA reported his position to the Departures North controller (DEPN). The pilot advised that the aircraft was 44 NM north of Sydney, and he was requesting an airways clearance. The secondary surveillance radar (SSR) transponder replies for HVA were not being received and that aircraft was not displayed on the DEPN radar display. DEPN misheard the transmission and assumed that the clearance request was from the pilot of TXK, which was displayed on the controller's radar display. The radar display indicated that this aircraft was 60 NM to the north-west of Sydney. This was a difference of 16 NM from the distance reported. DEPN issued a clearance for TXK to enter controlled airspace at 7,000 ft. The pilot of HVA believed this clearance was in response to his request and acknowledged the clearance but incorrectly read back the level as 6,000 ft. DEPN did not challenge the read back by the pilot of the incorrect level.

Approximately two minutes later, the pilot of TXK requested from DEPN a clearance to enter controlled airspace. DEPN re-issued the clearance at 7,000 ft. The pilot of that aircraft correctly read back the clearance.

The flow controller was concerned that HVA was not being displayed on the radar and requested the DEPN controller to attempt to contact that aircraft. DEPN transmitted to HVA and after receiving a reply from the pilot, requested the latter to change the aircraft's transponder code. This new code was observed on the display approximately 13 NM north of Sydney and 2.2 NM from the symbol for another aircraft at 6,000 ft. The required horizontal separation standard was 3 NM. There was a breakdown of separation.

The Sydney terminal radar consists of two radar systems; a primary radar with a range of 50 NM and an SSR which has a range of 250 NM. Consequently, aircraft with an inactive or unserviceable SSR transponder more than 50 NM from Sydney airport were not displayed. Pilots were required to check that an aircraft transponder was receiving and replying to an SSR. The pilot of HVA checked the transponder in flight and believed that the system was operating as he approached Sydney controlled airspace.

The callsigns of the two aircraft were distinctly different but some transmissions were truncated or clipped which made reception of the broadcasts difficult.

One of the methods available to a controller to identify an aircraft on radar was to correlate the observed and reported positions. When using this method a controller was required to ensure that the observed position was within the navigation tolerance of the reported position. The DEPN controller had other means available to him to identify an aircraft on radar. The investigation was unable to identify the radar identification method used by the controller.

ANALYSIS

The DEPN controller missed an opportunity to confirm the identification of the aircraft requesting a clearance when he did not correlate the observed radar position, of what he believed was TXK, with the actual position provided by the pilot of HVA. The difference between the positions was approximately 16 NM. This disparity in the positions could have alerted the controller to the possibility of a misidentification. However, the controller did not use this information to assist in the identification of the aircraft.

The pilot of HVA had an expectation of receiving a clearance from DEPN following his request. This expectation led him to believe that the clearance issued was for his aircraft, despite the clearance being prefixed with a different callsign and not at his planned level.

The pilot's subsequent read back of the incorrect level was not recognised by DEPN and the misidentification of the aircraft remained undetected.

The reason for DEPN not observing and querying the primary radar symbol from HVA was not ascertained. Similarly, the reason for the eventual operation of HVA's transponder was not ascertained.

SIGNIFICANT FACTORS

1. DEPN did not observe the primary radar symbol from HVA while the aircraft was within 50 NM of Sydney.

2. The SSR label for the HVA was not displayed on the controller's radar.

3. The controller did not correlate the pilot position report of HVA with the observed radar position on the display.

4. The pilot of HVA acknowledged and read back the clearance incorrectly.

5. DEPN did not challenge the incorrect level read back from the pilot of HVA.