The pilot, who was based at Mornington Island, was tasked to convey passengers from Mornington Island to Normanton in Cessna 206 registered VH-XGR. The pilot's intended track would have resulted in the aircraft overflying Bentinck Island, south-east of Mornington Island.

The flight departed at about 0915. Other pilots operating aircraft in the area reported that the weather conditions were not favourable for visual flight to the south of Mornington Island, but were acceptable to the north. Rain started to fall when XGR taxied for departure. After a take-off to the east the aircraft was observed to turn left and set course from overhead the airstrip.

Soon after departure the pilot was advised by the pilot of an aircraft maintaining 5,500 ft, and tracking for Karumba that the weather conditions enroute were a line of light showers.

At 0929 a pilot tracking from Doomadgee to Bentinck Island in a Cessna 206 operated by the same company as the accident aircraft was advised by the company through Brisbane Flight Service that visibility at Bentinck Island had reduced to 1,000 m in rain. That pilot subsequently reported in the circuit area at Bentinck Island at 0949.

At 0935, after obtaining the current position of the pilot tracking to Bentinck Island, the pilot of XGR reported that he was now diverting to Burketown, passing 3,500 ft on climb to 5,500 ft. The two pilots then changed to a company frequency. No further report from the pilot of XGR was recorded.

The aircraft did not arrive at either Burketown or Normanton. A subsequent search found articles, identified as being from XGR, in the water to the south of Bentinck Island. The damage sustained by these articles was consistent with the aircraft having struck the water at high speed.

Examination of recorded weather radar data available from a radar site at Mornington Island indicated a band of weather extending from just south of Mornington Island to north of Bentinck Island, and beyond. To conduct the flight as intended the pilot would have been required to negotiate this weather. Pilots who had arrived at Mornington Island before the departure of XGR reported that the cloud did not contain any thunderstorm formations. Conditions under the cloud were assessed as not suitable for VFR flight due to reduced visibility in rain.

The pilot was appropriately qualified and met the recent experience requirements to conduct the flight. His medical history did not indicate any condition that may have led to incapacitation. He had obtained a command multi-engine instrument rating nine months before the accident flight, but had not since conducted a flight in instrument meteorological conditions and had only flown a limited number of hours in simulated instrument flight conditions.

The aircraft was not certified to operate in instrument meteorological conditions and was not fitted with an autopilot, nor was it required to be. Although it was equipped with appropriate instrumentation, there was no requirement that they be maintained to instrument flight standards. No evidence was found to indicate that the aircraft was other than serviceable for flight in visual meteorological conditions.

Following an unsuccessful search for the aircraft, the investigation by the Australian Transport Safety Bureau was terminated. At that time, in the absence of sufficient aircraft material to enable a comprehensive examination, it was not possible to determine the factors that led to the accident.

In late 2001, Queensland Police sent the ATSB photographs and items of wreckage recovered from an area on the seabed near Sweers Island, east of Bentinck Island. Each photograph was examined and image enhancement techniques were employed to assist with closer inspection. On 8 March 2002, Queensland Police sent the ATSB a video of aircraft wreckage taken underwater at the accident site.

The items of wreckage sent to the ATSB's engineering laboratory for examination, and the wreckage viewed on photographs and video, were consistent with having originated from a Cessna 206 aircraft. While positive identification of the aircraft VH-XGR was not possible, on the balance of probability it is likely that the wreckage was that of VH-XGR.

The examination of the attitude indicator revealed that the aircraft impacted the water at an angle of bank of 135 degrees right-wing down (45 degrees inverted) and 35 degree nose-down attitude. That was consistent with the structural damage viewed on the photographs taken by the police.

The damage to the airframe components and propeller blades, and the evidence from the attitude indicator were consistent with a high velocity impact with the water following a loss of control of the aircraft. This damage signature has been evident in numerous accidents investigated by the Bureau where an aircraft has crashed following flight from visual into non-visual meteorological conditions. Scenarios which have led to similar accidents have included where the pilot was either not trained for such flight operations, or had limited or no recent experience in instrument flight conditions, or the aircraft was not appropriately instrumented.

The pilot's limited experience in instrument flight conditions may have been insufficient to prevent a loss of aircraft control had he inadvertently entered an area of low visibility in the Sweers Island area.

The ATSB's engineering report is available above in the Technical Analysis Report tab.

1. The flight crew and air traffic control staff did not brief effectively before the calibration flight.
2. The Astra crew was unaware that Brisbane Centre was responsible for management of a portion of R577.
3. The Astra crew was unable to maintain continuous two-way communications with flight service international.
4. The provision of radar coverage and use of secondary surveillance radar transponders in oceanic airspace assisted in the resolution of the conflict.

The briefing planned between the Astra crew and Williamtown Air Traffic Control staff did not occur and as a result, the air traffic control staff were not fully conversant with the Astra crew's intentions. Also, the Astra crew were unaware of the unique delineation in airspace management responsibilities for the area where they intended to operate. These aspects made it difficult for the crew to adequately prepare for contingencies and for air traffic controllers to understand the complex nature of the calibration task.

The Astra crew complied with the clearance issued by Williamtown Air Traffic Control. However, the clearance was issued without air traffic control being fully conversant with the flight profile. The misunderstanding was compounded by the Astra crew believing that their flight would be managed by Williamtown Air Traffic Control. If the crew had been aware of the ramifications of the Jordy Release, it was likely that they would have appreciated that the initial stages of the flight would pass back and forth between R577 and non-controlled airspace. Had they been aware of this fact and that consequently, they were responsible for their own traffic avoidance, the Astra crew may have ensured that air traffic services were advised of the intention to change level well in advance of commencing the climb to FL200. If the crew had been able notify flight service international of their intention to climb from 10,000 ft to FL200 it was probable that they would have been issued with traffic information on the Dash 8 and the conflict may not have occurred.

The operation of the Astra's transponder on the assigned code assisted in the resolution of the situation. An alternative for the crew was to select the transponder to the radio failure code of 7600, which was part of the aviation safety net. Given the complex nature of the task and the communication difficulties being experienced by them at the time, this action may have provided a more timely alert to air traffic agencies. Had air traffic agencies been alerted by the change in code to 7600, it is likely that air traffic control or flight service international officers would have either provided traffic information or initiated action to separate other aircraft in the vicinity of the Astra.

The Brisbane Ocean sector controller saw on radar an unidentified aircraft climbing through flight level (FL)180. The controller issued traffic information to the crew of a Dash 8 operating an instrument flight rules (IFR) flight from Lord Howe Island to Sydney at FL200. The crew of the Dash 8 sighted the unidentified aircraft at an approximate distance of 5 NM and 1,500 ft below them. The two aircraft passed with 3 NM lateral separation at the same level. The unidentified aircraft was subsequently identified as an Astra conducting an IFR calibration flight. It appeared that the crew of the Astra had not complied with Aeronautical Information Publication (AIP) procedures for changing levels in non-controlled airspace. These procedures require pilots of IFR category aircraft operating in non-controlled airspace to notify the relevant air traffic agencies of any changes in altitude/level. Investigation of the occurrence revealed that the Astra crew were not notified of a change in airspace management for their area of operations.

The Astra crew was conducting a calibration of a new radar that had been installed at Williamtown aerodrome. This required the aircraft to track outbound from Williamtown at 1,500 ft, in a direction clear of local operating areas and air routes, until radar coverage was lost and then return on the reciprocal track while climbing. Once the next altitude or level was reached the crew would immediately turn the aircraft to track outbound again. The manoeuvre was to be repeated at 10,000 ft, FL200, FL300 and FL400 and would conclude with the aircraft completing the task at approximately 220 NM from Williamtown.

The Astra crew had prepared and dispatched written briefs on the task to Williamtown and Brisbane Air Traffic Control (ATC) agencies. However, the calibration task schedule was amended and subsequently conducted 24 hours earlier than originally notified. The brief depicted the calibration flight as being a series of steps with an increase in altitude/level as the distance from Williamtown increased but did not depict that the aircraft would fly the reciprocal track at any stage. After the Astra had departed Williamtown to commence the calibration, the Williamtown approach coordinator briefed the Brisbane Flight Service International officer on the task, based on the briefing and other details as subsequently advised by the crew.

The general practice of the Astra crew was to conduct personal briefings with the responsible air traffic control staff on the day of a calibration task and this was their intention on the day of the occurrence. However, when the Astra arrived at Williamtown, the senior air traffic control officer who had planned to attend the briefing was not available. Consequently, the crew only briefed a technical ground party.

The Astra crew was issued a clearance by Williamtown Air Traffic Control to track via the 100 tactical air navigation aid radial on climb to FL210. On this track the Astra would transit Williamtown restricted area R577 which was promulgated as continuously active, 24 hours a day. The intended track of the Astra entered and exited R577 respectively at 25 NM and 130 NM east of Williamtown. The vertical limits for the area are from sea level to FL600. When not required for military operations a notice to airman (NOTAM) deactivating R577 for specific periods was normally issued by Williamtown Air Traffic Control. A deactivation NOTAM was not issued for the period of the calibration flight.

As an aid to airspace management, Brisbane and Williamtown Air Traffic Control agencies had agreed to automatically release portions of R577 and other restricted areas to Brisbane when the restricted areas were active. This agreement was published in the Northern New South Wales Manual of Air Traffic Services Supplement (MATS SUPP) which in turn was part of both Williamtown and Brisbane operating procedures. The agreement effectively transferred airspace management responsibility for the south-east portion of R577, known as the Jordy Release, from Williamtown Air Traffic Control to Brisbane Centre. The planned track of the Dash 8 passed through the Jordy Release.

The lateral and vertical limits for Australian airspace were published in the Airservices Australia Designated Airspace Handbook (DAH) and depicted on AIP charts. The DAH, charts or a NOTAM can be used for flight crew pre-flight briefing. None of the documents included the MATS SUPP provisions.

A letter of agreement between Brisbane Ocean sector, Brisbane Flight Service International and Sydney Flight Service 4 detailed the airspace management responsibilities for the Jordy Release when transferred to Brisbane Centre. The division of responsibilities was:

• Ocean sector
  That portion of the release above FL200 between 90 NM and 150 NM from Sydney and above FL245 outside of 150 NM Sydney,
• Flight Service International
  That portion of the release at FL200 and below that level outside of 90 NM from Sydney, and
• Sydney Flight Service 4
  That portion of the release below the control area steps inside 90 NM from Sydney.

The Ocean sector controller was required to separate IFR aircraft as if they were in controlled airspace. The officers of both flight service units were required to issue traffic information to pilots of IFR category flights, just as they would have for pilots of IFR flights in non-controlled airspace, in accordance with the Manual of Air Traffic Services (MATS) criteria. Part of the MATS criteria required traffic information to be issued when aircraft were climbing or descending through the level of another aircraft when these aircraft were within 15 NM or 10 minutes longitudinally or laterally. Ocean sector uses radar and procedural control methods to separate aircraft. Radar coverage extends to beyond the eastern limit of R577. Neither of the flight service units had access to radar services.

Because of the flexible airspace management arrangements for the Jordy Release, flight service international officers usually pre-empted requests for confirmation of the availability of planned routes for aircraft inbound to Sydney. Normal practice was to advise crews as early as possible when the area was active with military operations to enable them to commence tracking via alternative routes. The crew of the Dash 8 was not advised that their planned route was unavailable. The crew was subsequently advised to contact the Ocean controller at 140 NM from Sydney for a clearance.

The Astra crew reported that due to R577 being active, they believed that, their flight would be managed by Williamtown air traffic control. The Williamtown coordinator advised flight service international that the crew had been cleared to FL210 but that initially they would maintain 1,500 ft. The coordinator subsequently advised flight service international that the Astra had climbed to 10,000 ft. The Astra crew was instructed that they were leaving the Williamtown restricted area and to transfer to flight service international on high frequency (HF) radio. This was required as they were operating in that portion of R577 being managed by flight service international.

After several attempts, the Astra crew contacted flight service international on HF radio and was advised of another HF frequency to use if they were having communication difficulties. There was no further contact with the crew on HF radio. The flight service international officer attempted unsuccessfully to contact the crew. The problems with the HF radio communication were believed to be the result of propagation difficulties. Once it was apparent to the crew that HF communication was not viable they tried to establish communications with Brisbane Centre via VHF. The crew reported after the occurrence that because they were unable to advise any air traffic service agency of the next climb, from 10,000 ft to FL200, they broadcasted their intention on the VHF emergency frequency, 121.5 MHz. The investigation could not establish whether other crews heard the transmission.

The crew contacted the Nambucca Sector Controller and reported that their position was 120 NM east of Williamtown on the 100 radial and that the aircraft had left 10,000 ft on climb to FL200. The Nambucca controller confirmed that the Astra was tracking west and that at 110 NM from Williamtown the crew would commence a turn to track outbound. The Nambucca controller contacted the Ocean controller to report the Astra's position. At approximately the same time the Ocean controller was issuing a clearance to the crew of EA261 and shortly after noticed an unidentified aircraft approaching the Dash 8. The Nambucca controller issued traffic information to the crew of the Astra, who arrested the climb of their aircraft and then descended to FL185.

The Astra crew did not select the radio failure code of the aircraft's secondary surveillance radar transponder. The investigation did not establish why the crew did not change the transponder code.

A Brasilia VH-XFZ was on a visual approach to Cairns from the south-east and was tracking to left base runway 15. A Citation VH-PSU departed from runway 15 without a separation standard being applied by the approach controller between the two aircraft. The aircraft passed with approximately 500 ft difference in their altitudes when there was less than 3 NM laterally between them.

The controller could have either coordinated the use of a visual separation procedure with the aerodrome controller or the crew of either aircraft, or employed a 1,000 ft vertical separation standard or a 3 NM radar standard to ensure that the aircraft were separated.

The investigation revealed that the controller was aware that a separation standard was required. This was confirmed by the controller's request to the pilot of XFZ to report seeing PSU that was shortly to depart. However, subsequent actions limited the ability of the pilot of XFZ to comply with the request. If this sighting had been achieved, it would have allowed the transfer of separation responsibility from the controller to the pilot. This procedure did not provide separation assurance and was a "fail-unsafe" procedure as it relied solely on the pilot's ability to see the other aircraft and limited the controllers' options should the pilot be unable to comply.

When the crew of XFZ were unable to sight PSU the controller then monitored PSU's climb performance and assessed that the aircraft would not collide. However, vertical separation reduced to less than the standard when there was no radar standard being applied.

The use of a radar standard was constrained by the disposition and intended tracks of the aircraft. In this situation, the Manual of Air Traffic Services (MATS), 9-2-1, paragraph 19 states that a procedural separation standard shall be applied. Also, the controllers actions did not comply with MATS 4-1-1, paragraphs 4-6 which places greater emphasis on traffic planning and conflict avoidance by controllers instead of conflict resolution. The use of separation assurance techniques by the controller would have ensured the separation of the aircraft.

During the take-off roll, the crew of the Boeing 767 heard a loud bang sound so they immediately discontinued the take-off. A runway inspection by the airport safety officer and fire crews found fuel and engine components on the runway. The aircraft was towed to the company maintenance facility and the runway was reopened after approximately 30 minutes.

Maintenance inspection found metal particles in the tailpipe of the engine. An engine change was carried out and the aircraft was returned to service.

Disassembly of the removed engine found that a blade in the second stage high-pressure turbine (HPT) had failed. The liberated blade then caused catastrophic secondary damage to components downstream during its passage through the engine. The manufacturer's design features for failure containment prevented damage to the aircraft or other systems by trapping high-velocity debris within the engine. Some low-velocity debris was ejected from the tailpipe.

The remaining segment of the blade firtree root in the HPT disc was retrieved and examined. The examination revealed the presence of a casting defect in a cooling-air channel web of the firtree root. This led to initiation of fatigue crack growth and eventual fracture of the turbine blade. Fatigue crack initiation was associated with a discontinuity created during casting. It was evident that the fatigue crack did not intersect the outer surface of the blade prior to failure.

After completion of the examination, the blade was returned to the engine manufacturer who has been requested to furnish a report on the metallographic sectioning examination of this component.

The crew of the Dash 7, registered VH-UUM, were cleared to track visually via Kuranda. The crew of the Cessna 310, registered VH-XXT, were cleared to track visually via Stoney Creek. Both aircraft had flight planned IFR and were entitled to positive air traffic control separation. Such separation was not provided and the required radar separation standard of 3 NM between the two aircraft was infringed.

The investigation revealed that the strategy for separation employed by the approach controller did not provide a separation standard. Radar separation was an option, in accordance with the Manual of Air Traffic Services (MATS), 9-2-1, paragraph 19, if the departing aircraft had been issued a standard radar departure. Such a departure was not provided. Moreover, because vertical separation had not been employed, the controller had to rely on lateral separation to ensure the aircraft did not conflict. However, lateral separation would not exist if both aircraft were simultaneously east of a line Stoney Creek-Kuranda. There was no separation assurance. MATS 4-1-1, paragraphs 4-6 place significant emphasis on the need for controllers to apply separation assurance techniques.

Realising the potential confliction after take-off, the controller attempted to establish a visual sighting of the departing aircraft by the crew of the arriving aircraft. The visibility was reduced due to smoke haze, making a sighting unlikely. If a sighting had been achieved, it would have allowed the transfer of separation responsibility from the controller to the pilot. The crew of the arriving aircraft were unable to sight the departing aircraft. The controller then requested the crew of the arriving aircraft to make a right orbit but the crew were unable to comply due to high terrain. The crew suggested a left orbit, which was agreed to by the approach controller. The left orbit however, further reduced the distance between the two aircraft.

The crew of the departing aircraft then sighted the arriving aircraft, with the assistance of the aircraft's TCAS, and were able to visually maintain separation. Vertical separation was reduced to 100 ft when the aircraft were 1.5 NM apart. The required radar separation was 3 NM or 1,000 ft vertically.

1. The Adelaide flight progress strip in the tower was misplaced on the airways clearance delivery console during the handover/takeover of the surface movement control/airways clearance delivery positions.
2. The coordinator did not review the flight progress strip to ensure the crew had been cleared before coordinating the Sydney flight data record for VH-HYY.
3. The absence of ticks on the Sydney flight progress strip did not alert controllers to the fact that a clearance may not have been read back or issued.

Although the annotated Adelaide flight progress strip was accidentally placed on the airways clearance delivery console during handover/takeover, there were at least two chances of detecting the error (at the coordinator and aerodrome control positions, for instance) before the aircraft departed. The controllers were supposed to ensure that the flight progress strip annotations reflected the current status of the flight. They should have ticked the clearance to show that it had been issued and read back. Perhaps the controllers assumed the strips were correct because they had been forwarded from at least one other position. Alternatively, the controllers at the positions may have been distracted while managing other aircraft or tasks.

Because air traffic controllers need accurate flight information, they have to continuously assess and confirm data from different sources. Even if crews provide the destination when asking for taxi clearance, mistakes can still happen if controllers do not scrutinise the information.

The Australian Advanced Air Traffic Control System (TAAATS) held two flight data records for VH-HYY, one from Melbourne to Adelaide and the other from Melbourne to Sydney. The crew were cleared to Adelaide but the Sydney flight data record was coordinated in TAAATS. After the aircraft departed, the controller saw that its radar track did not "couple" with the flight data record. This was achieved when the air traffic system linked an aircraft's secondary surveillance radar track with the flight data record assigned to that code. Separation standards were not infringed.

Airservices Australia found that, in anticipation of a busy departure period, the controller operating the combined surface movement control and airways clearance delivery positions noted clearance details on all pending flight progress strips. The controller cleared the crew of HYY for Adelaide and ticked the clearance and altitude annotations on the strip after receiving a correct read-back. This was required to confirm that the clearance had been issued and read back correctly. After the surface movement control and airways clearance delivery positions were individually activated, and during handover/takeover, the Adelaide strip for HYY was accidentally placed on the airways clearance delivery console and the Sydney strip placed on the surface movement control console. When the crew sought a taxi clearance, the surface movement controller did not notice that the clearance annotated on the Sydney strip was unticked but still activated the strip. The strip was then passed to the coordinator position and the controller there changed the state of the HYY flight data record in preparation for the aircraft's departure. The coordinator processed the first observed record for that aircraft and did not notice that the clearance had not been ticked. The departure controller then received a system "preactive" electronic strip showing that HYY was taxiing for a departure to Sydney. The strip in the tower was then passed to the aerodrome control position. Neither of the two controllers staffing that position noticed that the clearance on the HYY strip had not been ticked. Controllers at each operating position were required to maintain and arrange their strips.

Because TAAATS gave a separate secondary surveillance radar code to each flight data record in the system, the Adelaide and Sydney flight data records for HYY had different codes. The HYY crew were later cleared for take-off and after departure, the Sydney flight data record did not link to the aircraft's radar track. After confirming that the aircraft track displayed on the radar was that of HYY, the departure controller told the crew to select the aircraft's transponder on the secondary surveillance radar code assigned to the Sydney flight data record. The track then linked to the flight data record and the electronic strip on the departure controller's display changed to active. Shortly after, the departure controller gave an amended clearance to the crew of HYY for direct tracking to Sydney. The crew replied that the flight was to Adelaide.

The Aeronautical Information Publication AIP GEN 3.4-36-38 gives the radiotelephony phraseology required around an aerodrome. When pilots seek a clearance and clearance delivery is in operation, they must provide the aircraft's flight number and the aerodrome where they first plan to land. When they seek a clearance to taxi, they may include this aerodrome if they wish. The automatic voice recording confirmed that the HYY crew had supplied their destination when seeking a clearance but that they did not include it when asking for a taxi clearance. In other words, they had complied with the AIP radiotelephony phraseology procedures.

1. Weather conditions deteriorated more rapidly and more severely than was initially forecast in the weather reports obtained by the pilot.
2. The pilot was unaware of amended weather information that accurately forecast the deterioration in weather conditions.
3. The pilot continued flight into non-visual meteorological conditions

The pilot obtained the correct weather forecasts for the flight. The investigation found no record of the pilot having updated his weather information during the flight. Consequently, although he expected a gradual deterioration of the weather he would not have had any warning of the more rapid deterioration, and greater severity of conditions.

It is likely the pilot only realised that the weather was significantly different from the forecast when he was tracking across the higher terrain south-east of Oberon. Due to his lack of exposure to similar weather, it is possible he delayed making a decision to divert until too late. Having flown into those conditions the pilot then found himself trapped between the ridges and the cloud base, unable to continue or turn back. His instrument flight skills would have been inadequate to attempt flight in cloud under those conditions. When the aircraft entered cloud the pilot was no longer able to rely on external visual references and probably became spatially disorientated. The aircraft subsequently entered a left turn, descended rapidly and collided with the ground. The accident was consistent with loss of control following flight in instrument meteorological conditions by a non-instrument rated pilot.

The pilot with two passengers was conducting a private flight in a Piper Archer from Merimbula to Bathurst, to be carried out in accordance with the visual flight rules (VFR). The intended route was coastal to Wollongong and then direct to Bathurst. The latter part of the route passed over the Oberon area where the elevation of terrain was between 3,300 and 5,000 ft.

At about 0900 EST the pilot telephoned a relative near Katoomba to obtain an appreciation of the weather in the area. He was told the conditions were overcast but clear. About 20 minutes later the relative tried unsuccessfully to contact him to advise that light rain had begun falling.

The pilot and his passengers arrived at Merimbula airport at approximately 0930. He asked the locally based flying instructor for weather details and was shown a facsimile copy of the current Area 21 forecast, obtained at 0911 from the AVFAX briefing facility. At the pilot's request the instructor obtained terminal area forecasts (TAFs) for Wollongong, Bankstown and Bathurst from the AVFAX briefing facility at 0957. The Area 21 forecast, which was valid for the period 0900 to 2100, indicated that visual meteorological conditions could be expected along the planned route, with areas of rain and showers extending east across the forecast area. Isolated thunderstorms were also expected to develop over the ranges along the planned track, and to slowly extend east after 1300. Conditions at Mt Victoria, south-east of Bathurst, would be suitable for visual flight until 1400. The Bathurst TAF, issued at 0410 and valid from 0600 to 1800, forecast visual meteorological conditions to exist throughout that period.

The pilot did not seek any further weather information from the instructor and did not submit flight details. He was later seen refuelling and preparing the aircraft for flight. At 1028 the pilot advised flight service of his departure from Merimbula. That was the only recorded communication between the pilot and flight service.

At approximately 1230 witnesses south of Oberon reported seeing an aircraft flying very low and at times circling. They reported that it occasionally entered patches of low cloud and disappeared from view behind higher terrain. Some of the witnesses reported the engine sounded as if it was revving and cutting. Witnesses in the area to the south and west of Oberon subsequently reported several similar sightings of the aircraft at about that time. At 1256 witnesses on a property 9 Km west-north-west of Oberon reported hearing an aircraft overhead. They could not see the aircraft because of fog and mist but heard it circle their house twice. The engine noise increased followed by the distinct sound of an impact. They subsequently found the wreckage of an aircraft approximately 250 metres west of the house. The occupants of the aircraft were fatally injured.

The aircraft had collided with grass-covered sloping terrain at an elevation of 3,300 ft. Examination of the accident site and wreckage determined the aircraft had been descending in a left wing low attitude under high power and at high speed. No defect that may have contributed to the accident was found in either the aircraft or its systems.

An amended Bathurst TAF issued at 1018 forecast significantly deteriorating conditions after 1100. Unlike the earlier forecast, it indicated that from 1100 visual meteorological conditions in the Bathurst area would have been marginal and at times non-existent. Similar conditions were confirmed by witness accounts of weather in the Oberon area at the time of the accident, and by a later analysis of data by the Bureau of Meteorology. Conditions depicted by the Sydney weather radar at 1300 included an area of high intensity rainfall south of Oberon.

The pilot held a Private Pilot Licence and a valid Class 2 medical certificate. He had undertaken navigation training between February and June 1998. His instructor reported that the navigation training had been undertaken in mostly ideal weather and he had not been able to demonstrate flight in marginal weather. The pilot had, as part of his training, received 3.3 hours instrument flight instruction but was not qualified to fly in instrument meteorological conditions. He had not recorded any further instrument flight training since his licence test in June 1998.

Subsequently, the pilot undertook training in the Piper Archer. He had been shown the operation of the aircraft equipment including the use of the global positioning system (GPS) to assist navigation. Since gaining his private licence qualification the pilot had made three extensive interstate flights. The instructor reported the pilot was cautious about the weather and if the forecast was doubtful he would contact an instructor for advice. Apparently, on at least one occasion, when the weather was unfavourable, he had terminated the flight short of his destination. The pilot hired the aircraft for three days and was not expected to return from Merimbula until the day after the accident.

Sequence of events

The Cessna Silver Eagle aircraft, a turbine-powered, pressurised Cessna 210, was conducting a private flight from Maroochydore to Bankstown under the Instrument Flight Rules (IFR), cruising at flight level (FL) 160. Meteorological conditions conducive to icing had been forecast for the route.

While enroute, the pilot faced adverse weather and requested a diversion around the weather. Air traffic control (ATC) cleared the aircraft to divert then, when clear, to track direct to Mount Sandon. The pilot requested, and was approved to, climb to FL 180. Twenty four minutes later, the pilot told ATC that he required a descent to FL 140 due to icing. Six minutes after that, the pilot stated that he required a further descent to FL120 due to icing, and four minutes later, requested descent to 10,000 ft due to icing.

Two minutes later, the pilot reported an engine failure. One minute and 43 seconds later he reported that he had lost generator power and that the aircraft was descending through 8,500 ft. ATC then asked the pilot to activate the emergency locator transmitter (ELT). A Distress Phase was declared and, after further attempts to communicate with the pilot were unsuccessful, search and rescue (SAR) action was started.

Several hours later, search aircraft found the wreckage on steep mountainous terrain, 380 m south-east of its last position showed by radar. The accident was not survivable.

Wreckage examination

Onsite investigation revealed that the right wing had failed before impact, both at midspan and at the fuselage attachment point, because of aerodynamic forces that exceeded the wing structural load limits. The empennage had also separated from the fuselage before impact. The right horizontal stabiliser and elevator were not present at the accident site. Objects thought to be parts of the missing empennage were sighted from the air. Their location was 330 m from the main wreckage site, and on the northern slope of a ridge. The main wreckage was on the southern slope. The wreckage trail was consistent with the direction of flight as recorded on radar.

The fuselage, with the engine and left-wing still attached, had impacted the ground in a steep nose-down, inverted attitude. The cabin section of the fuselage comprising the pressure hull, had remained intact until impact with the terrain. The landing gear and wing flaps were found to be in the retracted position.

The evidence showed that the propeller was still attached to, and was being driven by, the engine at impact. The engine and cockpit firewall, with most of the instrument panel attached, had separated from the fuselage during the impact sequence and had been destroyed by post-impact fire. Most of the left-wing was also destroyed by post-impact fire. The intensity of the fire suggested the aircraft was carrying a significant fuel load at impact. There was no evidence of any pre-impact fire.

The aircraft had been fitted with a fixed and two portable ELTs, all of which had been destroyed by impact forces.

The engine was subsequently stripped and inspected. The inspection revealed that the engine was producing significant power at impact. The wreckage examination did not reveal any pre-existing technical fault that would have contributed to the accident.

Aircraft

The aircraft was registered in the USA and was maintained to US Federal Aviation Administration requirements. It was fitted with an Allison 250-B17F/2 turbo-propeller engine. Section 2 page 5 of the approved flight manual supplement for the aircraft stated:
"For flight at ambient temperatures of 4 degrees Celsius and below, the fuel used in this aircraft MUST have an anti-icing additive in compliance with MIL-I-27686D or E or Phillips PF A55MB, incorporated or added into the fuel during refuelling in accordance with the additive manufacturer's instructions."

Section 2 page 9 of the approved flight manual supplement for the aircraft stated:
"Flight into known icing conditions is prohibited."

The engine-driven generator installed in this aircraft was designed to automatically shed all electrical load when engine compressor revolutions per minute (RPM) fall to 70%.

Inspection of the aircraft technical logbooks revealed compliance with all applicable Airworthiness Directives and Service Bulletins.

Fuel

The aircraft was refuelled before departure from Maroochydore. No evidence was found to suggest that anti-icing additive had been added to the fuel at that time.

On the day of the accident, several other aircraft, including one high-capacity regular public transport aircraft, had been refuelled from the same fuel supply as N62J. None of the pilots of these aircraft reported any problems with fuel.

Pilot

The pilot held a US commercial pilot certificate with a valid Class 2 medical certificate, a command instrument rating, and was endorsed for the aircraft type. His total experience was 3,229 hours with 629 hours on the aircraft type. He was reported as being a cautious pilot who planned his flights carefully and correctly applied inflight procedures. He was aware of the aircraft limitations about flight in icing conditions.

Pathological and toxicological examination did not reveal any evidence of any medical condition affecting the pilot that could have prevented him from safely operating the aircraft.

Weather

The amended area forecast showed rain and thunderstorms with a freezing level of 10,000 ft; moderate icing in the tops of large cumulus, altocumulus and altostratus cloud, temperatures of 2 degrees C at 10,000 ft and minus 6 degrees C at FL 140.

The actual freezing level was approximately 11,500 ft with severe icing and turbulence in thunderstorms. Conditions in the area at the time the pilot reported the engine failure were conducive to airframe and engine intake icing. Interpretation of the enroute weather reports suggested that the aircraft might have passed through a line of showers and thunderstorms.

The pilot reported that soon after take-off the engine oil temperature increased. He also reported that he considered the indication was likely to be an electrical malfunction based on previous occurrences of a similar fault although such occurrences had not been recorded in the helicopter's maintenance documentation. Despite the lack of secondary indications to confirm the existence of a major problem, the indication was apparently sufficient to raise a doubt in his mind as to whether or not he had properly secured the engine oil filler cap. There was no reference in the helicopter's flight manual that indicated any immediate action was required. Although there was no information to indicate that an immediate landing was required, the pilot conducted a continuous turning descent to an immediate landing rather than performing the recommended reconnaissance procedure.

The recommended reconnaissance procedure in which the pilot had been trained for conducting landings in confined or unfamiliar areas, noted that a high reconnaissance should be made at about 400 ft above ground level before making an approach. The procedure included recommendations on how to assess the likelihood of a wire hazard. In this case, the terrain was flat and the spur line led to farm buildings that were 3 km from the junction with the main power line. There were few, if any, impediments to recognising the existence of the spur line. Consequently, it is likely that if the pilot had conducted the prescribed reconnaissance procedure, he would have had a higher probability of seeing the spur line. The pilot's perception that an immediate landing was required appeared to have diverted him from conducting the recommended reconnaissance procedure prior to making the final approach. These actions may have been a reflection of his low level of aviation and helicopter flying experience.

The stowage of the glass bottles in the baggage compartment under the passenger's seat would have significantly reduced the impact absorption qualities of the seat. It could not be determined, however, whether the stowage of the glass bottles was a factor in the passenger not surviving the accident.

The inconsistencies between the pilot's recollection of events immediately prior to the accident, and the wreckage evidence which indicated that the helicopter was in a nose-low attitude and possibly travelling at relatively high speed, could not be resolved.

History of flight

The owner-pilot had used the Robinson R22 helicopter during the previous 14 days to transport himself and his assistant to several towns in the north-west of Western Australia in the conduct of his business. During the return journey to Geraldton, the pilot landed the helicopter the afternoon before the accident, at a relative's farm located near Binnu. At about 0850 WST on the morning of the accident, the helicopter departed from the farm to fly to Geraldton approximately 45 NM to the south. The pilot reported that about 10 mins after take-off and when he had climbed to about 500 ft, the helicopter's engine oil temperature indication rose. There was no other cockpit indication of a potential malfunction. He suspected an electrical problem associated with the indicator due to previous occurrences, but the indication also caused doubts in his mind as to whether he had properly secured the engine oil filler cap during the pre-flight inspection. Consequently, he decided to land to check. He reported that during the approach he saw the main power line and thought he was positioned such that he was clear of all power lines. The pilot reported that he did a reconnaissance of the proposed landing site by conducting a descending right turn from 500 ft. During the final approach, the helicopter struck a power line. The helicopter fell to the ground and was destroyed by the impact. There was no fire. The pilot sustained serious injuries and the passenger was fatally injured. The pilot reported that he never saw the wire and the last thing he recalled was feeling as though the helicopter had been "grabbed." He thought that the helicopter's airspeed was about 35 to 40 knots when it hit the wire.

Accident site

The accident occurred approximately 5 km south of where the helicopter departed. The helicopter struck the upper conductor of a dual-conductor spur line running at approximate right angles to a main transmission power line located about 500 m to the south-west. The helicopter struck the spur line two bays from the main line about mid span at a height of about 8.4 m. The span distance was 205 m. Seven bays, approximately 1100 m, of conductor was pulled from the insulators and poles by the impact and the wire was dragged about 42 m during the accident. As well as itself breaking, the conductor broke several steel ties as it was pulled from the poles during the accident sequence. The steel ties secured the conductor to the insulators.

Weather

Observations at Geraldton and information provided by witnesses who were in the area at the time, indicated that the wind was a light southerly. There was some low-level cloud and the temperature was about 20 degrees C. There were no reported restrictions to inflight visibility.

The helicopter

The helicopter was a Robinson R22 Alpha, which is a two-place, single main rotor, single engine helicopter constructed primarily of metal and equipped with skid landing gear. The maximum gross weight of the helicopter is 1370 lbs. The approved grade of fuel for the helicopter was 100/130-grade aviation fuel. 100/130-grade aviation fuel is dye-coloured green. Automotive petrol (MOGAS) is coloured red.

The pilot reported that he suspected the high engine oil temperature indication was an electrical problem based on previous occurrences although the occurrences were not recorded in the aircraft's maintenance release or logbook. He also reported that there were no secondary indications, such as a fall in engine oil pressure or the illumination of a warning light. The Robinson R22 flight manual noted, "When a red warning light comes on, select the nearest safe landing area and make a normal landing as soon as practical." If an engine oil light illuminates, the flight manual noted that it, "indicates possible loss of engine power or oil pressure. Check the engine tach and oil pressure gauge. Continued operation without oil pressure may cause serious damage to the engine and engine failure could occur." The flight manual emergency procedures did not include any actions in response to an increasing engine oil temperature indication. The helicopter's manufacturer reported that it was considered unlikely that a missing engine oil filler cap would result in sufficient oil being lost to result in either low engine oil pressure or high engine oil temperature. Several maintenance organisations reported that a missing engine oil filler cap might lead to an indication of low oil pressure.

Baggage space is located under each of the seats. Each seat is equipped with a combined seat belt and inertia reel shoulder strap. The Robinson Helicopter flight manual requires the fitment of a placard in each baggage compartment, part of which states, "Avoid placing objects in compartment which could injure occupant if seat collapses during hard landing."

The daily inspection certification and aircraft time-in-service section of the helicopter's maintenance release had not been completed by the pilot during the 14 days prior to the accident although the helicopter had flown at least 20.9 hrs on 5 separate days. The pilot reported that he had conducted the required daily inspections but he intended entering the data on arrival at Geraldton. The maintenance release also revealed that a required 25 hourly servicing, oil change and set of inspections were due about 4 hours prior to the accident. The pilot reported that he had conducted the required inspections although they had not been certified in the maintenance release. He also reported that he had not completed the required oil change because he considered that it was not necessary. The engine manufacturer however required the oil to be changed every 25 hours and this periodicity was reflected in the maintenance release requirements. Several maintenance organisations confirmed that the oil change was required. Because the daily inspections had not been annotated as having been completed and required maintenance had not been completed, the helicopter was not being operated with a valid maintenance release. The helicopter had not been modified to use MOGAS and neither the helicopter's manufacturer nor the Civil Aviation Safety Authority (CASA) had approved the use of the fuel type in the accident helicopter. The pilot had also stowed a container of fuel in the cockpit, which was not in accordance with the Civil Aviation Regulations (CARs) pertaining to the carriage of dangerous goods.

Wreckage

The main wreckage came to rest about 69 m beyond where the helicopter impacted the power line. The damage to the aircraft was consistent with ground impact in a nose low, left bank attitude. The left seat squab supporting structure was found deformed from compression type loads generated in the accident sequence. Empty glass bottles were found under the passenger's seat. The nose low, left bank attitude of the aircraft resulted in the greater part of the impact forces being transferred through the fuselage to the left seat supporting structure and its occupant. An examination of wreckage did not revealed any pre-existing mechanical problem that may have contributed to the accident. Wreckage evidence and the pilot's report indicated that the engine was operating normally before the accident.

The left seat-belt anchor point, in the centre of the cabin seating structure, had failed. This failure liberated the inner belt anchor point from the aircraft structure and rendered the left occupant restraint system ineffective.

The fuel tanks had ruptured during the accident and consequently, no fuel remained in the fuel tanks. A plastic container, almost full of fuel, was found amongst the main wreckage. The fuel was red in colour and smelled of automotive fuel. The pilot confirmed that the container was filled with MOGAS and that he had it available for emergency purposes. He also advised that he had, on occasion, used MOGAS in the helicopter. Before the wreckage was removed from the site, a very small amount of fuel was found in the helicopter's fuel line. The fuel appeared to be automotive fuel. The pilot declined to comment to the investigation about whether or not he had fuelled the helicopter with MOGAS prior to the accident.

Evidence, including wire scrape marks on the landing skids and damage to the power line, appeared consistent with the helicopter hitting the wire in a nose low attitude and possibly at a relatively high speed.

The pilot

The pilot had accumulated a total of about 290 hours flying experience, all in the Robinson R22. He gained his private helicopter pilot's licence 17 months prior to the accident and had flown about 26 hours in the 30 days prior to the accident.

The pilot had not received formal low flying training and was not authorised by CASA to operate the helicopter below the minimum altitudes prescribed in the CARs.

Flying procedures

The flight-training documentation provided by the training school that conducted the pilot's helicopter licence training, highlighted the need for vigilance against wires when landing in unfamiliar areas. The prescribed procedure for landing in unfamiliar areas recommended that a high reconnaissance involving a series of checks (including checking for hazards such as power lines) be made at about 400 ft above ground level before making an approach. The procedure included, "Do not descend until you are sure that there are no powerlines that are going to interfere with your operations. Look for anything that uses electricity e.g. houses, sheds, pumps, lights etc. If necessary follow along a nearby powerline to ensure it does not go anywhere near your landing area. Look for stay wires, crossbeams, junction boxes etc. to indicate change of direction or spur lines".

Regulations

The CARs also detailed the requirements pertaining to maintenance releases. A maintenance release ceases to be in force if a requirement or condition imposed in respect of the maintenance of the aircraft has not been complied with. Additionally, the regulations required the recording of total time-in-service of the aircraft on the completion of flying operations each day on the day.

The container of fuel was not packaged in accordance with dangerous goods requirements. The carriage of the fuel container in the helicopter cockpit was not, according to advice provided by the Civil Aviation Safety Authority, permitted by the CARs pertaining to dangerous goods.