The information presented below, including any analysis of that information was prepared principally from information supplied to the Bureau.

On 12 November 2005, a Piper Aircraft Corporation PA-31 Navajo, registered VH-DEQ, was being operated in accordance with the visual flight rules on a private flight from Ayers Rock, NT to Birdsville, Qld. At about 1235 Eastern Standard Time ¹, the aircraft was landed on runway 14 at Birdsville with the landing gear retracted. The two occupants, both pilots, were uninjured but the aircraft was substantially damaged.

The pilot flying reported that the aircraft was being ferried from Perth, WA, to Archerfield, Qld, via refuelling stops at Kalgoorlie, Ayers Rock and Birdsville, with an overnight stop at Ayers Rock. The flight also incorporated conversion training for the pilot flying in order gain a class endorsement for the aircraft type. The other pilot was a Grade 1 flight instructor, endorsed on the class of aircraft. The flight to Kalgoorlie, WA, was conducted as a dual training exercise and the pilot flying subsequently flew the aircraft under the supervision of the instructor ².

On the late downwind position in the circuit, the pilot flying reported moving the gear selector to the DOWN position. Both pilots reported that they usually checked for landing gear down indications but could not recall whether the three green Down-Locked lights or the red Not-Locked light were illuminated.

The instructor reported that when the aircraft was on final approach, he asked the pilot flying whether he had carried out the finals checks. Those checks included checking that the landing gear was down and locked. The pilot flying reported that he checked the aircraft was correctly configured for the landing. He also reported that the approach and landing was normal until the propellers contacted the bitumen runway. Neither the instructor nor the pilot recalled hearing the gear unsafe warning horn. The gear selector was still in the DOWN position after the wheels-up landing.

A gear unsafe horn activates when the landing gear is not locked down and the throttle setting on one or both engines is reduced below 12 inches of manifold pressure. During a normal powered approach, the throttle setting can be greater than 12 inches of manifold pressure until the throttles are closed just before touchdown.

The pilot's operating handbook for the Navajo advised that to lower the landing gear, the gear selector handle is pulled aft and then lowered to the DOWN position. That action opens the inboard gear doors, illuminates a red Not-Locked light and extends the landing gear. When the landing gear legs are locked down, the three green Down-Locked lights illuminate. Once the inboard gear doors are closed, the extension cycle is complete, and the gear selector automatically returns to a neutral position (Figure 1) and the red Not-Locked light extinguishes. In most other aircraft with retractable landing gear, the selector remains in the down position.

Figure 1: Landing gear selector (shown in a neutral position)

Following the wheels-up landing, a licensed aircraft maintenance engineer examined the landing gear system. The aircraft was lifted on jacks and the landing gear was manually extended. The engineer reported that the landing gear sequenced normally, the three green Down-Locked lights illuminated, and the gear selector returned to a neutral position. Subsequently, the engine-driven hydraulic pumps and the gear unsafe horn were checked and found to operate normally.

1. The 24-hour clock is used in this report to describe the local time of day, Eastern Standard Time (EST), as particular events occurred. Eastern Standard Time was Coordinated Universal Time (UTC) +10 hours.
2. A pilot cannot exercise command privileges, including in-command under supervision, on an aircraft until the type or class endorsement has been entered into the pilot's log book by the flight instructor or approved person.

A Piper Aircraft Corporation PA-31 Navajo, registered VH-DEQ, was on a private VFR flight when it made a wheels-up landing on Runway 14 at Birdsville, Qld. The two occupants were unharmed, but the aircraft was substantially damaged. The pilot flying was gaining experience on the aircraft under the supervision of a Grade 1 flight instructor as part of a class endorsement on the aircraft.

The pilot flying reported that on late downwind he moved the gear selector to the DOWN position. Both pilots believed the landing gear was down and locked but could not recall whether the three green Down-Locked lights had illuminated. The landing gear selector was still in the DOWN position after the landing.

The Pilot's Operating Handbook explained that the gear selector moved from the DOWN to a neutral position when the landing gear extension cycle was complete. It stated that the gear lights were the primary means of confirming the landing gear status.
A post-accident examination of the landing gear system by an engineer did not find any defect.

The investigation found that although the pilot flying may not have operated the aircraft's landing gear selector correctly, contributing to the wheels-up landing, neither he nor the instructor had effectively ensured that the landing gear was down and locked.

On 6 November 2005 at 1800 Eastern Daylight-saving Time, the flight crew of a Boeing Company B777-300 aircraft, registered A6-EBG, did not comply with an altitude restriction at WHALE (a waypoint located approximately 37 km east of Sydney Airport) while on the MARLN 5 standard terminal arrival route (STAR) to Sydney Airport, NSW. This incident was one of three incidents reported on the same day for the operator. An examination of the ATSB database found 20 incidents of noncompliance with air traffic control instructions or procedures by the operator over the six-month period to December 2005. Further analysis showed a recurrence of two events in particular. Those events were:

• the non-compliance with STAR altitude restrictions
• the non-compliance with operating restrictions for taxiway Alpha 4 at Sydney Airport.

Following notification of the noncompliance issues by the ATSB, the operator amended the relevant Route Manual Supplement (RMS) for Sydney Airport to include more comprehensive information on taxiway restrictions. Also, an operational notice was sent to flight crew advising them:

• to take precautions when clearing flight plan discontinuities from the flight management system (FMS) when on STAR or standard instrument departures (SID) procedures
• to resolve any ambiguity that may exist with Air Traffic Control (ATC) regarding clearances and operating restrictions.

The air traffic service (ATS) provider and the operator have also advised that air safety incident reports from ATS staff will be forwarded to the operator for information. The ATS service provider in conjunction with the operator is also investigating possible STAR procedure changes and the provision of additional taxi instruction to pilots at Sydney Airport.

The helicopter sustained a loss of tail rotor control while carrying out a power line inspection. It made approximately 12 to 15 full rotations before landing in a paddock. The pilot and two observers on board received minor injuries. The helicopter sustained minor damage.

Examination of the tail rotor revealed that the loss of control was due to failure of the inner tab of a tang washer. The washer locked the retaining nut holding the drive fork and the tail rotor assemblies onto the transmission output shaft. The failure of the inner tab resulted in looseness of the retaining nut and the split ring becoming dislodged. Consequently, the drive fork and the tail rotor assemblies were allowed to move freely along the transmission output shaft.

The ATSB was advised that at the helicopter rebuild a new tang washer was fitted. To inspect the washer, the retaining nut would have to be removed.

The operator sent the failed tang washer to the helicopter manufacturer to determine nature of the locking tab failure. The report had not been received at the time of writing this report.

A search of the ATSB database, for the 1995 to 2005 period, revealed no records of similar tail rotor control problems. The Civil Aviation Safety Authority Service Difficulty Report database, for the same period, contained only the record of the tail rotor control problem from this occurrence.

The manufacturer advised that they have received two worldwide reports of a broken locking tab since 1988.

At about 1425 Western Standard Time on 22 October 2005, an Air Tractor AT-602 aircraft, registered VH-NIT, impacted terrain approximately 100 metres south of the perimeter fence of Ballidu aerodrome, WA. The pilot was carrying out a series of familiarisation flights. He was the sole occupant of the aircraft and was fatally injured.

Witnesses recalled that the aircraft had dropped a quantity of water at low level over the aerodrome. Soon after that drop, the nose of the aircraft pitched steeply towards the ground and the aircraft descended into terrain.

The aircraft impacted terrain in a slightly right wing-low, almost nose-level attitude at a high vertical rate of descent, but with low forward speed.

Examination of the wreckage did not identify any anomaly that could have affected the normal operation of the aircraft during the accident flight. Examination of the engine indicated that it was producing power at the time of terrain impact.

Toxicology testing revealed that the pilot had ingested cannabis. Specialist medical advice was that the results of the toxicology testing would be consistent with the pilot using cannabis sometime during the 24 hours prior to the accident.

The physical and witness evidence was consistent with the pilot losing control of the aircraft at low altitude, most probably as the result of an inadvertent aerodynamic stall. There was insufficient altitude to recover the aircraft to level flight.

The pilots of the Saab were instructed by air traffic control to depart Townsville on a heading of 350 degrees magnetic, to ensure a lateral separation standard existed between the Saab and the arriving Cessna 310. However, on departure, the pilots of the Saab continued their left turn, through the assigned heading. That reduced the lateral separation between the Saab and the inbound Cessna and resulted in an infringement of separation standards. This analysis examines the development of the occurrence and highlights the safety issues that became evident as a result of the investigation.

Despite a correct readback to the controller and recording the assigned heading on the Takeoff and Landing Data Card, the copilot forgot about the heading instruction as he commenced the turn after takeoff. The pilot's familiarity with the visual departures to the west, and his expectation of a visual departure on this occasion, may have contributed to the occurrence.

A person's capacity to remember to perform a task in the future can be adversely affected by workload, distraction, lack of mindfulness because of familiarity, and the elapsed time between any instruction and the proposed activity. Although the sterile cockpit policy practiced by the crew reduced the risk of distractions, the takeoff necessarily involved a high workload and there was a period of elapsed time between the assignment of the heading and initiation of the turn. Application of a cue such as setting the assigned heading on the EHSI heading selector or on the course deviation indicator would reduce the risk of flight crew forgetting assigned headings.

Monitoring by the pilot not flying is a means of early identification of heading deviations. In this case, the pilot in command was busy adjusting the power levers and did not immediately realise that the aircraft's heading had diverged from the assigned heading. Although the pilot not flying has a number of actions to perform during a departure, monitoring critical phases of the flight should be a high priority.

The controller's plan for separating the Saab and Cessna was based on establishing a lateral separation standard based on the Saab's assigned heading of 350 degrees and the Cessna's inbound radial of 329 degrees. The aerodrome controller and approach controller both became aware that the Saab had turned through the assigned heading, but were initially uncertain of the crew's intentions. It was a dynamic situation and the approach controller attempted to mitigate the effect of the Saab's displaced departure track by alerting the Cessna pilot to the proximity of the Saab and instructing him to conduct an orbit.

Although there was an infringement of separation standards, the Cessna's orbit delayed the closest point of approach, allowing time for the Saab to climb, which increased the vertical distance between the two aircraft as they passed. The left orbit would have been more effective had the Saab continued onto the flight planned track. However, there was little time for the approach controller to establish radio contact and ascertain the crew's intentions before the Saab crew turned their aircraft back to a heading of 350 degrees and passed almost overhead the Cessna with about 500 ft vertical separation between them.

The Traffic Alert Collision Avoidance System (TCAS) alerted the Saab crew to the proximity of the Cessna and reduced the risk of collision.

Sequence of events

On 13 October 2005 at 0618 Eastern Standard Time, a Saab Aircraft AB 340B (Saab), registered VH-UYA, departing Townsville Airport, Qld, came within the minimum separation standard of 1,000 ft vertically and of 3 NM horizontally of an inbound Cessna Aircraft Company 310R (Cessna), registered VH-TFP. There was an infringement of air traffic control separation standards.

The crew of the Saab was operating a scheduled passenger flight to Trepell, in central Queensland, in accordance with the instrument flight rules. Air traffic control issued a clearance to the crew to track via waypoint CATEY, a track of 243 degrees magnetic from Townsville. At 0611, the crew taxied for runway 01 ¹. After the crew reported ready for departure, the aerodrome controller issued the crew with a departure clearance, including an instruction to turn left, heading 350 degrees, visual. The pilot in command confirmed the instruction with the copilot. The copilot, who was the pilot flying, then read back the clearance to the aerodrome controller. Both pilots reported that the departure clearance was written on the Take-off and Landing Data Card before completing the pre-take-off checks and commencing the take-off roll.

Recorded information showed that as the Saab was rolling, the Cessna was 9 NM from Townsville, inbound from Cairns, Queensland on the 329 radial, and was on descent to 1,800 ft.

When the Saab had reached an altitude of between 600 and 700 ft the copilot commenced a left turn, engaged the autopilot, and selected a heading of about 210 degrees to intercept the planned outbound track of 243 degrees. At about 1,000 ft the pilot in command, as the pilot not flying, set the power levers to climb power. During the turn, at a heading of about 290 degrees, the pilot in command realised that they had flown through the assigned heading and alerted the copilot. The copilot reported that at about the same time he also realised they had flown through the assigned heading. He disengaged the autopilot and quickly turned the aircraft to the right onto the assigned heading of 350 degrees. During the turn, the Saab's Traffic Alert and Collision Avoidance System (TCAS) produced a traffic advisory (TA) consisting of an aural alert of 'traffic traffic' and the crew observed an amber symbol on the TCAS display that was indicating traffic below them. The crew attempted to sight the traffic but were unsuccessful. The pilot in command advised the approach controller that they were turning onto 350 degrees.

Both the approach controller and the aerodrome controller noticed that the Saab appeared to be turning as if to intercept the flight planned 243 radial. The aerodrome controller attempted to contact the Saab crew however, at that time the crew were in the process of transferring to the approach frequency and had not yet established contact. The approach controller provided traffic information to the pilot of the Cessna and when the pilot reported that he had not sighted the Saab, the approach controller instructed him to make a left orbit. The Saab crew subsequently contacted the approach controller and advised that they were turning onto a heading of 350 degrees visual, passing 2,200 ft. The approach controller passed updated traffic information to the Cessna pilot who then sighted the Saab about 500 ft above him and 0.5 NM ahead.

Recorded radar information indicated that when the horizontal distance reduced to approximately 3 NM between the closing aircraft, there was 400 ft vertical separation, and the Saab subsequently flew about 500 ft directly over the Cessna.

Operational aspects

Prior to engine start, the Saab crew set the Electronic Horizontal Situation Indicator (EHSI) heading selectors to the runway heading and the course deviation indicators to the outbound track of 243 degrees.

The operator did not require any change to the EHSI heading selectors or course deviation indicators in response to heading assignments in departure clearances. The operator required pilots to set the EHSI heading selector to runway heading in readiness for a one engine inoperative situation. It was common practice for the operator's crews to confirm a departure clearance with each other before it was written down and read back to the controller.

The pilot in command indicated that, as the pilot not flying, he monitored the conduct of the flight. However, there was no specific operator requirement for the pilot not flying to monitor the turn and ensure that the pilot flying captured assigned headings.

The Saab crew reported that they were observing the 'sterile cockpit' policy specified in the operator's aircraft operating manual. That policy prohibited discussion about anything except the immediate operation of the aircraft while an aircraft was climbing or descending below 10,000 ft. They indicated that their workload was normal and that they were not rushing. The copilot considered that he was not tired and there was no apparent reason for him forgetting about the assigned heading. He also said that most of the Saab operations from Townsville involved visual departures to the west and the assignment of radar headings with departure clearances was unusual.

The TCAS fitted to the Saab provided aural and visual traffic advisories when an aircraft equipped with a functioning transponder was within about 45 seconds of the projected closest point of approach. When an aircraft was within approximately 30 seconds of the closest point of approach, the TCAS issued aural and visual resolution advisories. The operator's requirements for crew response to a TCAS traffic advisory was: 'Conduct a visual search for the intruder. If successful, maintain visual acquisition to ensure safe separation.'

The weather conditions were reported to be a light wind with greater than 10 km visibility and 1 to 2 eighths cloud coverage at 2,000 ft.

1. Runway 01 heading is 016 degrees M.

On 13 October 2005, at 0618 Eastern Standard Time, a Saab Aircraft AB 340B (Saab), registered VH-UYA, departing Townsville Airport, Queensland, came within the minimum separation standard of 1,000 ft vertically and of 3 NM horizontally of an inbound Cessna Aircraft Company 310R (Cessna), registered VH-TFP. There was an infringement of air traffic control separation standards.

The pilots of the Saab were instructed by air traffic control to depart Townsville on a heading of 350 degrees magnetic, to ensure a lateral separation standard existed between the Saab and the arriving Cessna. However, on departure the pilots of the Saab continued their left turn through the assigned heading, before turning their aircraft back to a heading of 350 degrees. The approach controller provided traffic information to the pilot of the Cessna and when the pilot reported that he had not sighted the Saab, the approach controller instructed him to make a left orbit. The Saab passed almost overhead the Cessna with about 500 ft vertical separation between them.

Despite a correct readback to the controller and recording the assigned heading on the take-off and landing data card, the Saab copilot forgot about the heading instruction as he commenced the turn after take-off. The pilot in command, as the pilot not flying, intended to monitor the conduct of the flight but was busy adjusting the power levers and did not immediately realise that the aircraft's heading had diverged from the assigned heading.

Following the occurrence the operator of the Saab issued two standing orders.

The overriding survivor, witness and physical evidence was that the helicopter's engine was operating normally up to and including at the time of ground impact. On that basis, the investigation concluded that the performance of the engine had not contributed to the development of the occurrence.

Application of the requirements of the Aeronautical Information Publication (AIP) to the time of last light at Yalda Downs meant that a pilot in command who did not hold a night Visual Flight Rules (VFR) rating should have planned to arrive at Yalda Downs no later than 1816. In addition, the reported thin layer of cloud in this instance suggested that the planned arrival time should probably have been adjusted to earlier than 1816. The reported time of departure from Border Downs of 1800, and normal time interval for the planned flight to Yalda Downs of 1 hour 15 minutes, meant that the occurrence pilot attempted a flight for which:

• he was not qualified
• the equipment standard of the helicopter was not adequate.

Each increased the likelihood, and therefore risk that the pilot might become disoriented in the dark night conditions, resulting in a situation from which he was unable to recover.

The content of the approved flight manual (AFM) meant that the pilot ought to have been aware of the risk of his becoming disoriented when operating the helicopter in dark night conditions. The reported operation of the helicopter at about 30 ft above ground level minimised the time available for the pilot to recover from any disorientation before impacting the ground. In addition, it was likely that the climbing right U-turn eroded the already marginal outside references that the pilot may have gained as a result of identifying the lights and road as he passed north abeam Calindary. As indicated to pilots in the Safety Notices in the AFM, the likely result was that the impact with the ground was almost inevitable.

The action of the pilot to request successive property owners along the planned route to illuminate their homesteads' external lighting could have been interpreted to have had the secondary benefit of acting as a replacement for the flight notification requirements for flight through a Designated Remote Area. However, that was not an approved means of providing flight notification, and was based on the assumption that each of those property owners would be at home and respond to the pilot's radio transmissions.

That lack of a formal flight notification, and the apparent omission by the pilot to carry an Emergency Locator Transmitter meant that, had the accident not been observed by the witnesses at Calindary, the subsequent search and rescue effort could have been delayed. Any delay in locating the survivor had the potential to have:

• adversely affected the survivor's subsequent recovery from his injuries
• significantly complicated the survivor's injuries
• diminished the survivor's chances of survival.

At about 1800 Central Standard Time on 6 October 2005, a Robinson Helicopter Company model R22 Beta helicopter (R22), registered VH-HUZ, departed Border Downs, NSW on a private flight to the pilot's property at Yalda Downs, NSW with the pilot and one passenger on board. The helicopter subsequently crashed near a homestead at Calindary Station (Calindary), fatally injuring the pilot and seriously injuring the passenger.

A hearing witness¹ at Border Downs who was also a pilot and endorsed to fly the R22, had previously flown the occurrence helicopter. He reported that the helicopter 'sounded completely normal' during the take-off and departure from Border Downs. He indicated that the normal time interval for the flight to Yalda Downs was about 1 hour 15 minutes.

Witnesses at a number of properties along the route flown by the pilot reported that, as the flight progressed, the pilot requested by radio for each of them to illuminate their external homestead lights. The reason given by the pilot for those requests included, earlier in the flight, for the pilot to 'get his bearings' and, as the helicopter approached Calindary, to assist the pilot to identify two sets of power lines that crossed the main west to east road about 1 and 3 kms west of the property respectively. In response to the pilot's request, the property owners at Calindary reported that they parked their vehicle on top of a sand embankment that was about 100 m south of the main road. The vehicle's spotlights, and a third hand-held spotlight, were illuminated in the direction of the helicopter's anticipated approach.

The pilot advised the property owners by radio that he had sighted their spotlights. The property owners reported that they suggested to the pilot that he should land at Calindary and use one of their vehicles to return to Yalda Downs by road. The pilot declined that suggestion and indicated that, after picking up the road from Calindary to Yalda Downs, he would continue with the flight. The property owner estimated that the helicopter was below 30 ft above ground level (AGL) at that time, and described the helicopter's 'powerful white lights' as being visible 'down amongst the trees'. The survivor indicated that the pilot manoeuvred the helicopter in order for the helicopter's landing lights to criss-cross the road.

One of the witnesses at Calindary, with extensive experience flying aeroplanes, stated that there was nothing abnormal about the sound of the helicopter or its engine as it passed the vehicle's position, or immediately prior to the ground impact.

The survivor stated that, shortly after passing Calindary, the road appeared to merge with the surrounding bush and the pilot turned the helicopter to visually reacquire the road. The property owners at Calindary reported that the helicopter commenced a climbing right U-turn, before returning in a westerly direction and descending at an estimated angle to the horizon of 20 to 30 degrees. The survivor indicated that, during the turn and until the impact with the ground:

• he heard no abnormal noises from the helicopter
• he did not observe the illumination of any warning lights in the cockpit
• there was no apparent apprehension or degree of panic displayed by the pilot.

At about 1921, the helicopter impacted a sand hill a number of times and was destroyed by the impact forces and post-impact fire.

The pilot held a private pilot (helicopter) licence, was endorsed to fly the R22 and was reported to have about 9,000 hours flying experience. The pilot did not hold a night Visual Flight Rules (VFR) rating. The requirements of Civil Aviation Regulation (CAR) 174C(1) included that the pilot was required to have held that rating in order to conduct a flight at night under the VFR.

The pilot last undertook a medical examination in order to renew his Class 2 Medical Certificate in January 2002. There was no evidence that:

• the pilot finalised the administrative requirements for the renewal of that certificate
• the pilot held a valid Class 2 Medical Certificate at the time of the occurrence
• the Civil Aviation Safety Authority (CASA) had given the pilot permission to continue flying without a current medical certificate.

CAR 5.04(1) required that:

Without the permission of CASA, the holder of a flight crew license must not perform a duty authorised by the license if the person does not hold a current medical certificate that is appropriate to the license.

That meant that on the day of the accident, the pilot should not have been performing the duties that were authorised by his license.

The helicopter was first registered in Australia on 3 May 2005 and was reported to have flown about 130 to 140 hours since its delivery flight to Yalda Downs on 1 August 2005. An examination of the helicopter's maintenance records found that the helicopter was certified for day VFR flight and equipped and maintained in accordance with existing regulations and approved procedures. The helicopter was not equipped for flight under the night VFR, nor was it installed with an Emergency Locator Transmitter (ELT)².

The helicopter's weight and centre of gravity were estimated to have been within the prescribed limits at the time of the occurrence.

It was reported that the pilot would have refuelled the helicopter to capacity from the aviation gasoline fuel source at Yalda Downs prior to departing for Border Downs earlier that day. A witness at Border Downs indicated that the pilot did not refuel the helicopter at that location. It was estimated that at the time of the accident, about 24 L of fuel remained on board the helicopter. That would have been sufficient for the remainder of the planned flight to Yalda Downs.

A Bureau of Meteorology (BoM) examination of the forecast weather and meteorological observations from the Tibooburra Automatic Weather Station³ indicated that there was no significant weather, no low-level cloud, and no reduction in visibility in the region of Tibooburra at the time of the occurrence. The investigation determined that the times of sunset, and of the end of civil twilight for the relevant locations along the planned west to east route included:

The pilot was reported to have accessed a private weather source via the internet prior to the departure from Border Downs. The available information from that source included the observed surface wind for a number of locations in the general vicinity of the flight and the weather forecast and times of sunrise and sunset for Broken Hill. Sunset for Broken Hill on the day of the occurrence was published by that source as 1809.

A witness at Border Downs reported the weather as being 'good', with a wind of about 10 to 15 kts from the west-south-west, and a cloud base of above 1,500 ft AGL. The weather at the accident site at the time of the accident was reported by witnesses to include: a light north-westerly wind; a 50% overcast layer of thin cloud, with a high base; good visibility; and no horizon. Witnesses reported that it was 'pretty dark, as in black'.

Examination of the NSW Police and other photographic evidence indicated a low angle of impact with the sand hill at a relatively high speed, which compromised the integrity of the helicopter's cockpit area. That was consistent with the reported 85 m wreckage trail and witness reports of the helicopter's approach towards the ground.

The damage to the helicopter's landing skids and engine mount frame was consistent with a slightly nose-down, right angle of bank at ground impact. One of the main rotor blades separated from the main rotor head at its hinge bolt attachment point, consistent with static overload as a result of the blade's impact with the ground. The damage to that main rotor blade confirmed that the main rotor was rotating at that time. The tail boom appeared to have failed in overload and separated from the main wreckage following the initial impact with the ground. The relatively minor torsional shear indications evident on the tail rotor driveshaft, and the nature of the damage to the tail rotor blades, indicated that the tail rotor had ceased rotating prior to its impact with the ground.

Based on the available information, there was no evidence that material failure or component malfunction had contributed to the development of the occurrence.

At the time of writing this report, the pilot's post mortem report was not available to the investigation team.

There was no report by the witnesses to the occurrence of an in-flight fire. The source of the post-impact fire was from fuel that had spilled from the ruptured helicopter fuel tanks. The ignition source of the fire could not be confirmed, but was most likely from the hot engine exhaust.

CAR 252A specified that a pilot in command of an aircraft that was not an exempted aircraft⁴ may only begin a flight if the aircraft either:

• was fitted with an approved and functioning ELT, or
• carried an approved and readily accessible portable ELT that was in working order.

The helicopter was not an exempted aircraft and it was reported that the pilot normally carried a portable ELT during flight. The survivor indicated that he had not observed a portable ELT in the helicopter prior to or during the occurrence flight, and the item was not identified by the NSW Police amongst the wreckage of the helicopter, or at the site of the accident. AusSAR⁵ reported that an emergency signal was not identified at or about the time of the accident.

The flight was within the central Australian mainland component of the Designated Remote Area that was promulgated in Appendix III to Civil Aviation Order 20.11. That required the carriage of sufficient survival equipment for sustaining life appropriate to the area being overflown, and either the submission of a SARTIME⁶ flight notification to Air Traffic Services (ATS) or for a pilot in command to leave a flight note with a responsible person. It was reported that the pilot and passenger carried sufficient clothing in case the decision was made to remain overnight at Border Downs. ATS records indicated that a SARTIME was not submitted to that agency, and a flight note was not left at either Border Downs or Yalda Downs for the occurrence flight. Witnesses at Yalda Downs indicated that the first confirmation that the pilot intended to return that night was via a radio call from the pilot at about 1900 to 1915, indicating that '[he] would be late [arriving at Yalda Downs]'.

The Aeronautical Information Publication (AIP) requires that:

Unless the pilot in command holds a Command Instrument Rating or night VFR (NGT VFR) rating and the aircraft is appropriately equipped for flight at night, a VFR flight must not depart from an aerodrome:

1. before first light or after last light; and
2. unless the ETA [Estimated Time of Arrival] is at least 10 minutes before last light after allowing for any required holding.

Last light was interpreted by the AIP to equate to the end of civil twilight ⁷. In addition, the AIP alerted pilots to the potential for the presence of cloud cover to the west of an aerodrome, and a number of other variables to adversely affect a flight arriving at its destination near the end of daylight. Sunset was highlighted as 'having no relevance when calculating daylight operating times for the VFR pilot.'

The AIP also placed altitude restrictions on the operation of an aircraft under the night VFR. That included that a pilot should not operate an aircraft under those rules at a height lower than the published lowest safe altitude (LSALT) for the route, or a height that was calculated in accordance with the requirements of the AIP, except under certain prescribed circumstances. Depending on the calculation methodology applied by a pilot, the LSALT for the route Border Downs to Yalda Downs was at least 2,020 ft above mean sea level (equivalent to about 1,500 ft AGL at Calindary).

The Approved Flight Manual for the helicopter included a number of Safety Notices that were relevant to the operation of the helicopter at night. Those notices included that:

• Flying a helicopter in obscured visibility due to fog, snow, low ceiling, or even dark night can be fatal.
• Loss of the pilot's outside visual references, even for a moment, can result in disorientation, wrong control inputs, and an uncontrolled crash.
• …[the pilot] loses control of the helicopter when he attempts to turn to regain visibility but is unable to complete the turn without visual references.
• [pilots should] be sure you NEVER fly at night unless you have clear weather with unlimited or very high ceilings and plenty of celestial or ground lights for reference.

1. A witness who heard, but did not observe the takeoff.
2. Crash-activated radio beacon that transmits an emergency signal that includes the position of a crashed aircraft.
3. The closest station to the site of the accident, being about 49 NM north-north-west of that location.
4. Exempted aircraft means high capacity regular public transport or charter aircraft, single seat or turbo-jet powered aircraft, or balloons, airships or gliders.
5. Australian Search and Rescue - in general terms, AusSAR coordinates the response to aviation SAR incidents across Australia.
6. The time nominated by a pilot for the initiation of Search and Rescue action if a report has not been received by the nominated unit.
7. Period at sunset when the sun's centre is between 0°50' and 6° below the horizon.

The helicopter with the pilot and one passenger onboard, was returning to Yalda Downs Station from Border Downs Station after last light. As it overflew Calindary Station homestead, which is approximately 46 km west of the intended destination, the helicopter was observed to gain height and conduct a right turn. The helicopter then descended and impacted the ground about 500 m from the homestead. The helicopter was destroyed by impact forces and the post-impact fire. The pilot was fatally injured and the passenger sustained critical injuries.

Examination of the aircraft wreckage and accident site indicated that the aircraft impacted terrain at a steep angle and at high speed. In addition, the investigation concluded that the engine was producing power at the time of the accident.

The recorded Air Traffic Services (ATS) radar data indicated that the autopilot was engaged prior to the aircraft entering a steep left descending turn. The abruptness of the turn and the high rate of descent indicated that the autopilot was no longer controlling the aircraft. The autopilot could be disconnected by either pressing the electric trim switch or manually overriding the controls. The pilot was familiar with the route being flown and would be unlikely to have deliberately diverted from the intended flightpath. There was no significant weather in the area at the time of the accident, so the pilot would not have had to alter his heading to maintain visual flight.

If the pilot had deliberately disconnected the autopilot and manoeuvred the aircraft, the resultant flight path would probably not have been as abrupt as the recorded ATS radar data indicated. Therefore, the autopilot was probably disconnected by the pilot making an unintentional control input.

The investigation was unable to determine the reason for the sudden control input, but the circumstances are consistent with pilot incapacitation. The pilot was the only occupant of the aircraft who could manipulate the controls with the autopilot disconnected. The passenger, due to the usual seating arrangements, would have been unable to render assistance to the pilot, or assumed control of the aircraft, prior to the accident, if the pilot had become incapacitated.

History of the flight

At about 0855 Eastern Standard Time¹ on 24 September 2005, a Raytheon Aircraft Company Beechcraft A-36 Bonanza, registered VH-BKM, took off from Murwillumbah, NSW, on a private flight to Coonabarabran, NSW, with one passenger, who was the pilot's wife, under the visual flight rules. The pilot had not submitted a flight plan or nominated a SARTIME² and there was no requirement to do so. The pilot and passenger regularly flew return flights from Coonabarabran to Murwillumbah in this aircraft.

The aircraft was subsequently reported to be missing on 28 September 2005, and a search was commenced. The wreckage of the aircraft was located on 29 September 2005. The aircraft had impacted a heavily timbered hill on a private property 'Millera', located approximately 35 km east of Tenterfield. The aircraft had been destroyed by impact forces and a post-impact fire (Figure 1), and both occupants were fatally injured.

Figure 1: View of impact crater looking north-west

Operational Information

The pilot was 71 years old and held both commercial and private pilot licences for aeroplanes and had a valid Class 2 medical certificate. He held a pilot's licence for over 50 years and had previously owned and operated an aerial agricultural business. He had a total aeronautical experience of approximately 13,000 flying hours.

The aircraft had been owned and operated by the pilot for the previous 14 years. Maintenance records indicated that the aircraft had a valid maintenance release which was issued on 27 January 2005 and was valid for 12 months. The aircraft maintenance release was unable to be located in the wreckage, however the estimated total time in service of the aircraft at the time of the accident was 3,231 hours. The engine had been rebuilt and fitted to the aircraft in April 1992.

The aircraft was fitted with a two-axis autopilot which included separate roll and pitch engagement, altitude hold and automatic and manual electronic pitch-trim. The autopilot could be disconnected by pressing down on an electric pitch-trim switch on the control wheel, or by manually overriding the controls. The aircraft was fitted with a single control wheel.

Prior to the flight to Murwillumbah the aircraft was refuelled at Coonabarabran, from a fuel bowser owned by the pilot. Witnesses reported that the aircraft had been refuelled to its maximum capacity. Fuel records for the fuel supplied to the bowser indicated that the fuel sample in the supply truck was clear and free of sediment. The local aero club had been supplied with 400 L of fuel from the pilot's bowser and had not reported any problems with the fuel.

Performance calculations were used to estimate the fuel burn from Coonabarabran to Murwillumbah and from Murwillumbah to the accident site. These calculations indicated that approximately 140 L of fuel would have been on-board the aircraft at the time of the accident. Discolouration of tree foliage at the accident site and the extent of the post-impact fire confirmed that there was fuel in the aircraft when the accident occurred. Weight and balance calculations showed that the aircraft was within centre of gravity limits for the final flight.

Information provided by the Bureau of Meteorology indicated that a low-pressure trough was present to the west of Tenterfield on the morning of the accident. The weather forecast and actual observations indicated that the flight was conducted under visual meteorological conditions. Witnesses reported clear weather in the vicinity of the accident site.

The pilot had not submitted a flight plan for the flight or contacted air traffic control for an area QNH³ and was not required to do so. The recorded Air Traffic Services (ATS) radar data indicated that the aircraft was operating on a transponder code of 1200^4.

A review of recorded radar data indicated that the aircraft had been maintaining a stable heading and altitude for most of the flight, which was consistent with the autopilot having been engaged.

The aircraft had then descended from a cruising altitude of about 6,300 ft above mean sea level (AMSL) to a final recorded altitude of about 3,800 ft AMSL at a rate of approximately 5,000 ft/ min. The accident occurred at an approximate elevation of 1,000 ft AMSL.

The recorded radar data of the aircraft's flight path was superimposed on a topographical chart that indicated that the aircraft had made a sudden left turn over the area of the accident site (Figure 2).

Figure 2: Radar plot of final segment of flight

There were no recorded radio transmissions from the aircraft prior to departure from Murwillumbah, or during the flight. The aircraft was fitted with a fixed emergency locator transmitter; however, it was destroyed at impact and was not capable of transmitting a distress signal.

Wreckage and impact information

The aircraft wreckage was fragmented and damage to the aircraft structure was consistent with a high-speed impact. There was no evidence of an in-flight breakup, birdstrike or in-flight fire prior to the accident and a technical examination of the engine and propeller indicated that they were producing power at the time of the accident.

Ground contact marks indicated that the aircraft impacted the ground in a left wing-low, nose-down attitude. Damage to the tree canopy in the vicinity of the impact crater indicated an impact angle of 72 degrees to the horizontal (Figure 3). The aircraft's direction of flight at the time of the accident was estimated to be 290 degrees Magnetic.

Figure 3: Tree canopy damage

Post-mortem medical examination was unable to determine if the pilot had experienced any incapacitation prior to the accident. The pilot's medical records indicated that he was taking regular medication to control blood pressure and that he recently had undergone a minor surgical procedure to remove skin cancers but there was no evidence that either had a bearing on the accident.

Witnesses reported that the passenger normally travelled in the second row of seats, which faced rearwards. The passenger would occupy the seat diagonally across from the pilot (Figure 4) and only communicate with the pilot occasionally during a flight. There was no evidence of the passenger having any aeronautical experience.

Figure 4: Seating configuration of aircraft

1. The 24-hour clock is used in this report to describe the local time of day, Eastern Standard Time (EST), as particular events occurred. Eastern Standard Time was Coordinated Universal Time (UTC) + 10 hours.
2. The time nominated by a pilot for the initiation of search and rescue action if a report has not been received by the nominated time.
3. QNH is the altimeter subscale barometric pressure setting to provide altimeter indication of altitude relative to mean sea level. Area QNH is representative of the QNH of any location within a particular area.
4. A transponder is a receiver/transmitter which will generate a reply signal upon proper interrogation of an air traffic control radar signal.

On the morning of 24 September 2005, a Raytheon Aircraft Company Beechcraft A-36 Bonanza, registered VH-BKM, was being flown by the owner pilot on a private flight from Murwillumbah, NSW, to Coonabarabran, NSW, with one passenger. The pilot had not submitted a flight plan or nominated a SARTIME and there was no requirement to do so.

The aircraft was reported to be missing on 28 September 2005, and a search was then commenced. The wreckage of the aircraft was located on 29 September 2005. The aircraft had impacted a heavily timbered hill on a private property 'Millera', located approximately 35 km east of Tenterfield. The aircraft had been destroyed by impact forces and a post-impact fire and both occupants were fatally injured. Witnesses reported clear weather in the vicinity of the accident site.

The recorded radar data indicated that the aircraft was maintaining a stable heading and altitude which was consistent with the autopilot having been engaged. The aircraft then descended from a cruising altitude of 6,500 ft above mean sea level (AMSL) to a final recorded altitude of 3,800 ft AMSL, at a rate of approximately 5000 ft/min.

The pilot was 71 years old and held both commercial and private pilot licenses for aeroplanes with a valid Class 2 medical. The maintenance records indicated that the aircraft had a valid maintenance release which was issued on 27 January 2005.

Weight and balance calculations showed that the aircraft was within centre of gravity limits for the final flight.  Discolouration of tree foliage at the accident site and the extent of the post-impact fire indicated that fuel was present when the accident occurred.

The accident is consistent with the pilot becoming incapacitated, the aircraft departing controlled flight and subsequently impacting terrain. The possible reasons for any incapacitation could not be determined.