The pilot was carrying out spraying operations and had already spread two hopper loads of spray medium onto a cotton crop. Weather conditions were fine with clear skies and light winds from the north-north-east. The hopper was again filled, and two swathe runs were completed. The pilot reported that on the third swathe run, he left the pull-up manoeuvre to clear trees too late, and the aircraft's propeller collided with branches.

The aircraft initially gained about 100 ft following the collision, however, it then commenced to lose height. The pilot quickly realised that the impact had caused damage resulting in a loss of power and/or thrust. In an attempt to improve the aircraft's climb performance, he selected the dump valve to the fully open position and jettisoned the remaining hopper contents. This action failed to arrest the sink rate of the aircraft and it subsequently stalled into trees and collided with the ground. Whilst the pilot escaped with minor bruising, the aircraft was consumed by fire.

The pilot planned a flight from his base at Tooradin Vic, to Torquay Vic, accompanied by his son who also held a private pilot's licence.

The pilot advised that although he was familiar with the Torquay airfield layout he had not landed there before. Prior to leaving Tooradin he obtained airfield information from the Aircraft Owners and Pilots Association (AOPA) Airfield Directory and telephoned the operator for approval to land. He inquired about local conditions and was told that there were parachute operations at Torquay that day.

When he arrived in the Torquay area, the pilot listened out on the appropriate frequency and heard another pilot announce that that he was landing on runway 18. The pilot joined crosswind for a landing on runway 18, and while in the circuit observed the marked taxiway and worn take-off area at the threshold of runway 18.

On final approach to land, the aircraft collided with powerlines placed along the road adjacent to the threshold of runway 18. One powerline passed over the fuselage, damaging the horizontal and vertical tail surfaces. The other powerline broke the cockpit canopy and snagged on the roof structure. This powerline was pulled from the pole and stretched, allowing the aircraft to travel 70 metres before settling onto the ground in a level attitude. The pilots stayed in the aircraft until electrical power was disconnected. The aircraft was substantially damaged.

The "Special Procedures" section of the Torquay entry in the Airfield Directory did not mention the power line. AOPA advised that the details contained in the directory were supplied by the airport operator. The operator advised BASI that he had not brought the line to the attention of the pilot when he telephoned for permission to land.

There were two thresholds in use on runway 18 at Torquay, one for take-off and one for landing. Because of the powerlines, the airport operator had placed displaced landing threshold markers some 150 metres into the 805-metre strip in an endeavour to establish an approach gradient that would give adequate clearance over the powerlines. The markers were white and may not have established an effective contrast with the airfield surface under the prevailing dry conditions.

The take-off threshold was adjacent to the fence line with taxiway markers and runway edge markers delineating the take-off area.

The powerlines were made of steel which had a light-grey galvanised finish. The lines were fitted with 200-mm diameter orange marine buoys, the upper sections of which had bleached white. Power supply company records show that the orange marine buoys had been fitted some 8 years prior to the accident. The power supply company manuals did not contain standards for marker buoys, nor was there any requirement to check for ultraviolet degradation during the 3-yearly powerline inspection cycle.

The markers pre-dated the formulation of the Australian Standard for powerline marking.

The accident occurred in bright but overcast lighting conditions at the end of a hot dry summer so that the airfield surface was light brown in colour. The dry background, the oxidised wires, the degraded orange markers, and the displaced landing threshold markers were all of a similar colour to the airfield surface. Therefore, the powerlines would have been very hard to detect.

Because the pilot had not been warned of the existence of the powerlines he would have had a lowered expectation of their presence.

After the accident the pilot said that he considered the use of separate landing and take-off thresholds confusing, especially when the latter was neither adequately marked nor mentioned in the airfield directory.

Safety action

1. The operator is ensuring that all pilots who telephone for landing approval are thoroughly briefed on the existence of the powerline and the use of the displaced landing threshold.

2. The operator has enlarged the property and extended the runway. This has allowed the displaced threshold to be placed approximately 300 metres from the fence line and the powerline.

3. The operator has revised the entry in the AOPA airfield directory to include details of the powerline and the displaced threshold.

As a result of the investigation into this occurrence, the Bureau has made the following recommendations:

R970153: The Bureau of Air Safety Investigation recommends that the Electricity Supply Association of Australia make known to its members the circumstances of the accident and make appropriate use of the applicable Australian Standard (AS 3891.1) when marking powerlines.

R970177: The Bureau of Air Safety Investigation recommends that the Australian Airport Owners Association make known to its members the circumstances of the accident. The association should also recommend to its members that they contact their local electricity supplier if they believe any powerlines affecting their airfields are not marked in accordance with the Australian Standard.

R970178: Windsock Productions, publishers of The Country Airstrip Guides, gathers information regarding aerodrome and landing areas by asking operators to fill in a survey form and return it to them. The Bureau of Air Safety Investigation recommends that Windsock Productions amend that survey form to include, as examples, a detailed list of possible hazards, obstacles and special procedures an operator needs to consider when completing the form.

R970179: AOPA, which publishes the Airfield Directory, gathers information regarding aerodrome and landing areas by asking operators to fill in a survey form and return it to them. The Bureau of Air Safety Investigation recommends that AOPA amend that survey form to include, as examples, a detailed list of possible hazards, obstacles and special procedures an operator needs to consider when completing the form. The Bureau also recommends that AOPA inform its members of the circumstances of this accident.

Sequence of Events

The pilot was conducting aerial inspections of local roads affected by recent flooding. On board with the pilot were two council inspectors. The pilot reported that the helicopter struck a powerline as he was positioning for a closer look at a damaged section of roadway. The helicopter then impacted the ground coming to rest on the side of the road.

One passenger received minor injuries, the pilot and second passenger exited the helicopter without injury.

The helicopter was fitted with a Pointer 3000 Emergency Locator Transmitter which activated automatically.

The pilot reported that he had obtained a weather briefing from the Bureau of Meteorology at Cairns, prior to the flight. This information including early morning observations from Mareeba Airport. After selecting a launch site to the south-east of Mareeba, Winds in the area were again assessed using a weather balloon. The departure and flight were uneventful until north-east of Mareeba, when the pilot became aware that the surface wind was a southerly, gusting between 10 and 15 kts.

During the approach to land, at about 90 ft above ground level, the balloon was effected by a wind rotor near some trees. The rotor distorted the canopy and caused it to lose heat. As a result a high descent rate developed. The pilot estimated that about 50 ft of height was lost before he was able to arrest the descent using the burner. During the latter part of the descent, the basket and lower flying wires struck the branches of a tree, causing damage to lower panels of the canopy. A fast landing then ensued. After landing, the canopy was further damage when it became entangled in a barbed wire fence.

The pilot reported that a rain shower was experienced some minutes after the landing. He believed that the unusual localised wind during this accident was due to the approaching rain.

The pilot reported that during the take-off run the aircraft was not accelerating very well due to the soft wet surface.

At about 70 knots the pilot raised the nose in an attempt to get the main wheels off the runway to allow the aircraft to accelerate in ground effect. The pilot said that as soon as the aircraft lifted off it veered slightly left and was about to settle onto the ground again, so he closed the throttles and tried to maintain directional control on the ground. The aircraft entered mud and grass to the left of the runway for about 200 metres. The nosewheel then broke off, the propellers struck the ground, and the aircraft came to rest in about 8 metres.

The passenger who was an engineer, had previously run the left engine as it was suspected to not be producing full power. No fault was found with the engine. During the accident take-off the engineer had noted that the left engine was performing normally.

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.