Collision with terrain

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 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.

The pilot was reported to have conducted a similar low-level manoeuvre to that which preceded the accident on several previous occasions. On that basis, the investigation team considered that it was unlikely that the passenger was at the controls of the aircraft at the time of the accident. The manoeuvre left little or no margin for error and required sound judgement and skill. Although the pilot may have possessed those skills, no evidence was found of his ever having undertaken the appropriate check to assess those skills and obtain approval to conduct low-level aerobatic manoeuvres.

Repetition of the manoeuvre over a period of time may have led to the pilot gaining a false sense of security and may have led to the pilot becoming complacent about the inherent dangers involved with such manoeuvres. The manoeuvre performed by the pilot earlier that day at another location was commenced from a 'high-speed' flypast. The associated energy would have allowed the aircraft to convert speed to height and climb higher and attain a greater altitude for recovery than the manoeuvre performed during the accident flight. That manoeuvre was commenced from a take-off roll that did not use the full runway length available. When combined with a tailwind component, it was unlikely that the aircraft attained adequate airspeed to safely complete the intended manoeuvre by the end of the strip. It was also possible that the pilot was unaware of the windshear or had not considered its affect on the aircraft's climb performance.

Although the aircraft appeared to have stopped spinning to the right just before impact, the pilot had insufficient height to avoid a collision with the ground. Had the stall warning been operating, it could have provided the pilot with an earlier indication of the stall condition and thus enabled him to initiate a recovery earlier in the development of the manoeuvre.

The affect of the pilot's medical condition on his judgement or decision-making could not be determined. However, some aspects of the pilot's behaviour were not consistent with compliance with rules and regulations or good airmanship. These included conducting low-level aerobatics without approval, ignoring concerns expressed by peers, operating with an unserviceable stall warning indicator and ignoring weight and balance limitations. Furthermore, the pilot flew the aircraft knowing that he was suffering from a medical condition that was being reviewed by the Civil Aviation Safety Authority (CASA) and having been advised by CASA that he was not to fly until the results of the review were known. Disregard for the rules governing the conduct of flight and the operation of the aircraft removed safety defences that were established to prevent this type of accident.

On 15 May 2005, at 1535 Central Standard Time, an American Champion Corporation Citabria 7GCAA aircraft registered VH-TUF, with a pilot and passenger, took off from Stonefield private airstrip in South Australia for a local private flight. Shortly after becoming airborne, the aircraft crashed. Both occupants were fatally injured. The aircraft was destroyed by impact forces and a post impact fire.

After start up, the pilot performed a turn on the ground of more than 360 degrees before taxying on the north-east strip. The aircraft engine was heard powering up on the strip into the north-east and shortly after became airborne. After becoming airborne, the aircraft was observed to remain approximately 10 feet above the strip, and remained at that height until the end of the strip. At about this point, the aircraft was observed to enter a near vertical climb. At an estimated height of 500 feet above ground level, the aircraft stalled in the vertical position, before entering a right hand spin. The aircraft completed one and a half turns in the spin before it appeared to recover. At the point where the aircraft appeared to have recovered from the spin, it impacted the ground.

The investigation determined that the aircraft on the accident flight was 20kg over maximum all up weight (MAUW). The increased weight would have the effect of increasing the stall speed of the aircraft, thereby reducing its performance. It was also determined that the pilot took off north-east with a quartering down wind component, and attempted a vertical climb with a wind gradient of approximately 30kt and at 500 feet from the south, above ground level. This wind gradient would have significant impact on the aerodynamic performance of the aircraft, and the pilot may not have achieved the height he intended before it stalled.

On 8 March 2005, the Gippsland Aeronautics Pty Ltd GA-8 aircraft, registered VH-FGN, was carrying emergency relief supplies from Muelaboh to Patek in Aceh Province, Indonesia, as part of the Tsunami relief effort. The aircraft occupants comprised the pilot and one passenger.

At about 1326 Eastern Daylight-saving Time on 7 March 2005, the pilot of a Cessna Aircraft Company 310R, registered VH-FIN, took off from runway 30 Right at Tamworth Airport, for Scone, NSW. Approximately 1 minute after becoming airborne, the pilot reported flight control difficulties. At about 1329, the aircraft impacted the ground in a cleared paddock about 7 km west-south-west of the airport. The pilot was fatally injured, and the aircraft was destroyed by the impact forces and post-impact fire.

Examination of the aircraft's mechanical flight control systems, autopilot and electric trim system did not reveal any evidence of pre-impact malfunction. Those results, however, were inconclusive due to the extensive impact and fire damage. A bent hand tool found in the wreckage was not implicated in the development of the accident.

A periodic maintenance inspection carried out in the days before the flight resulted in the rudder trim tab being set at the full right position and possibly aileron and elevator trim tabs being set at non-neutral positions prior to the flight. There were indications that the pilot was rushed and probably overlooked the rudder and aileron trim tab settings prior to take-off. The aircraft flight path reported by witnesses was found to be consistent with the effect of abnormal rudder and/or aileron trim tab settings.

The investigation found that aircraft operating checklists produced by aircraft operators did not always include the autopilot and electric trim procedures located in the supplements of aircraft operating handbooks/flight manuals. At the time of the accident, the training and guidance generally provided to pilots did not emphasise the management of flight control difficulties including autopilot and electric trim related difficulties.

Following the accident, the aircraft operator and the maintenance provider advised that they had reviewed and amended some procedures. The Civil Aviation Safety Authority advised that a Civil Aviation Advisory Publication titled Multi-engine Aeroplane Operations and Training will be issued by July 2007 and that three items have been forwarded to the Safety Promotion Branch for consideration/action.

ANALYSIS

The investigation found that there was no evidence of a pre-existing defect in the helicopter that may have contributed to the occurrence, nor was there any evidence of a medical condition that could have affected the pilot's ability to control the helicopter. Consequently, the investigation concluded that in the prevailing environmental conditions, the accident was consistent with pilot spatial disorientation. This analysis examines the development of the occurrence and highlights a significant risk associated with night VFR operations.

The pilot departed for Eurella homestead 6 minutes after civil twilight in moonless, overcast, and probably showery conditions that were likely to restrict visibility to less than the required 5 km. Except for the homestead lights, the ground lighting or celestial illumination required by the Aircraft Flight Manual was not available. Although the pilot had flown at night on two recent occasions (23 and 26 August 2004), those flights did not fully satisfy the night VFR recency requirements and were probably over a well lit area. Given the pilot's limited recent and overall helicopter night flying experience, and the forecast weather conditions, it is unlikely that the pilot planned to conduct the return flight at night. The pilot had probably used the helicopter to move cattle and that task may have taken longer than expected. The proximity of the homestead, the local knowledge of his passenger, the night VFR capability of the aircraft and access to GPS information may have influenced the pilot to attempt the return flight.

The track information recovered from the hand-held GPS showed manoeuvring after 1830 that suggests that the pilot, probably using GPS information, made several attempts to track to the homestead, but was unable to do so. It is likely that during the manoeuvring the pilot was at a low altitude, attempting to maintain visual contact with surface features, possibly with the assistance of the landing lights. Such visual contact would have enabled control of the helicopter and clearance from terrain. In the absence of a consistently discernable horizon, any visual contact with the homestead lights would not have enabled the pilot to determine the helicopter's attitude. Prior to the impact, the pilot may have lost visual contact with the surface due to cloud and/or rain and become spatially disorientated.

The pilot may have attempted to control the helicopter by reference to the flight instruments. However, he had not logged any instrument flight time in a helicopter and had not been exposed to significant night-flight away from metropolitan areas. The relative instability of the helicopter and the different operating environment meant that the pilot's considerable aeroplane night and instrument flight experience was not directly transferable to night VFR helicopter operations. Consequently, spatial disorientation could have developed rapidly.

Flying the helicopter at a low altitude at night with cloud and/or showers in an area with little lighting was a very demanding task with little margin for error. However, once the helicopter became airborne after civil twilight, there were few options available to the pilot. The pilot's lack of helicopter instrument flight experience would probably have precluded consideration of climbing to the lowest safe altitude and tracking to an aerodrome with an instrument approach. Given that the adverse weather was widespread, diversion to another location while maintaining external visual reference was also an unlikely option.

A landing at a location other than the homestead was an option. It is possible that the accident occurred when the pilot became spatially disorientated in the adverse conditions while attempting to land the helicopter. However, it is also possible that, unable to communicate with the homestead, the pilot avoided an out-landing due to the consequent difficulty in reaching the homestead without transport.

Illumination of the clutch light as indicated by the stretched filament may have resulted from clutch operation during flight or from disruption during the impact. If the clutch light had illuminated during flight it may have distracted the pilot and contributed to spatial disorientation.

As a result of the separated ELT antenna cable, the search and rescue effort was significantly affected. However, in this case, the nature of the impact and the extent of injury to the occupants indicated that the search and rescue effort would not have influenced their survivability.

The circumstances of this occurrence highlight the risk of spatial disorientation during night VFR operations and reinforce the significance of the cautions included in the helicopter manufacturer's safety notices SN-18 and SN-26.

SIGNIFICANT FACTOR

The pilot departed after civil twilight in conditions where a natural horizon was probably not discernible and consistent visual reference to surface features was not likely.

FACTUAL INFORMATION

History of the flight

On 8 September 2004, the owner/pilot of a Robinson Helicopter Company R44 Raven II helicopter, registered VH-JWX, conducted a private flight under the visual flight rules (VFR) from Coffs Harbour, NSW to Eurella Station, Qld. The flight included a landing at Roma, Qld where the pilot refuelled the helicopter with 180 L of Avgas from the bulk underground fuel storage supply.¹ The pilot then continued to Eurella Station, located approximately 54 km west of Roma, arriving at 1705 Eastern Standard Time. The pilot shut down the engine and the property owner boarded the helicopter for a pre-arranged local flight. The pilot made several attempts to start the engine, during which it backfired a few times. Once started, the engine seemed to function normally.

The helicopter departed the homestead at 1725 in a northerly direction. A person on an adjoining property about 7 km north of Eurella homestead saw the helicopter operating to the east late in the afternoon. He reported that the helicopter conducted a number of take-offs and landings in what appeared to be the same general area over a period of about 30 minutes. He saw the helicopter depart in a southerly direction at about 1830.

The next reported sighting was by a person at Eurella homestead who, in poor light conditions, saw what appeared to be the helicopter's landing light to the north of the homestead. The light moved toward the west of the homestead. Soon after, that person again saw the light to the west and expected the helicopter to land at the homestead within a few minutes. However, she became concerned when the helicopter did not arrive and telephoned an employee of the property owner to report her concern. The employee contacted the Australian Search and Rescue organisation (AusSAR) and search action was initiated. The helicopter was located the following morning in open, rolling country, 3 km west of Eurella homestead. The two occupants were fatally injured, and the helicopter was destroyed.

Search and rescue

AusSAR reported that it was notified at 1947 that the helicopter was overdue. Weather conditions were unsuitable for an air search, but a surface search was initiated. AusSAR advised that no ELT signal was received on 8 September by satellite or by aircraft at high altitude passing within 130 km of Eurella Station. An ELT signal was detected on two satellite passes early on the morning of 9 September. The signals were identified as originating from separate locations; one approximately 22 km to the south-west, and the other approximately 22 km to the south-east, of Eurella Station. However, those signals were not merged by the satellites as coming from the same source, so they were of little assistance in the search. Local aircraft were tasked to begin a search at daylight on 9 September and the wreckage was located at 0708 by the crew of a search aircraft. Accident site information

The accident site elevation was about 30 m below the ground elevation at the homestead. The homestead was not visible from the accident site.

Figure 1: Aerial view of the accident site

GPS track information

The helicopter was fitted with a fixed global positioning system (GPS) receiver, and also a handheld GPS receiver mounted in a cradle on the instrument panel. The fixed receiver did not contain a non-volatile memory card, but the handheld unit did. Track and ground-speed data for the occurrence flight was retrieved from the non-volatile memory card. Altitude information was not retained in the memory card.

Figure 2 displays the GPS recorded track of the helicopter overlaid in blue on a 1 in 250,000 scale topographical map of the area. The local times that the helicopter was at various locations are depicted.

Figure 2: GPS track overlay, with the landing sites A, B, C and D

The GPS data showed that the helicopter landed five times during the flight. Those positions are depicted on the map and are described as follows:

The data indicated that, after the helicopter departed position B at 1827, it initially tracked almost directly toward the homestead, but that the track then veered south-west. That track was clear of the high ground indicated by the 400 m contour near Mt Muttaby, as depicted on the chart at Figure 2. There are distinct features in the helicopter's track after 1830, indicating that the pilot turned toward the homestead on four separate occasions between 1830 and 1840, only to turn away each time. The accident occurred on the fifth occasion that the helicopter's recorded track turned in the approximate direction of the homestead.

Subsequent to the occurrence, an employee from Eurella Station found that cattle had been moved from the paddock that included positions A, C, and D, to an adjoining paddock. Those paddocks were linked by a gate adjacent to position B. The employee recalled that the property owner had intended to move the cattle to the adjoining paddock and that the gate adjacent to position B was the gate through which he would have expected the cattle to be moved.

Pilot information

The pilot held an air transport (aeroplane) pilot licence and a command multi-engine instrument rating. He had extensive aeroplane flying experience, including regular public transport turbo-jet aircraft and corporate turbo-jet aircraft operations in Australia and overseas. His aeroplane flying experience exceeded 10,000 hours and included 1,418 hours of night flight and 711 hours of instrument flight.

The pilot obtained a private pilot (helicopter) licence on 23 September 1998 and had about 582 hours helicopter experience. He obtained a night VFR (helicopter) rating on 12 September 2000 and since that date had recorded about 11 hours helicopter night flight. Almost all of the logged flights were in the Sydney metropolitan area. Helicopter night flying recorded by the pilot in the two years prior to the occurrence was 0.4 hours on 23 August 2004 and 0.6 hours on 26 August 2004. That night flying most likely occurred during the latter stages of flights to the Sydney metropolitan area.

There was no record of the pilot having received any specific training in operating helicopters in remote areas or dark night conditions where there was little or no ambient lighting. No helicopter instrument flight time was logged.

The pilot held a valid medical certificate. Post-mortem and toxicology examinations did not reveal any pre-existing condition that might have affected the pilot's ability to safely conduct the flight.

Helicopter information

The pilot purchased the helicopter new in early August 2004. At the time of the occurrence the helicopter had operated for 34.1 hours. The maintenance release was valid and the documentation indicated that all applicable maintenance and regulatory requirements had been met.

The helicopter was equipped and certified for night VFR operations. Instrumentation included an airspeed indicator, artificial horizon, sensitive pressure altimeter, turn coordinator, horizontal situation indicator, global positioning system indicator, and vertical speed indicator.

The helicopter was equipped with twin landing lights in the lower nose section. The lights were fitted with 100 watt spot globes and, according to the Aircraft Flight Manual, were 'set at different angles to increase the pilot's field of vision'. Both lights were activated by the one switch which was mounted on the cyclic control centre post.

A row of eight amber warning lights located at the top of the flight instrument panel included a clutch warning light. A further six warning lights were positioned at the top of the centre pedestal.

The helicopter's engine was coupled to the rotor drive system via four double-stranded vee-belts. After engine start, an electric actuator would tension the belts when the pilot engaged the clutch switch. The actuator sensed belt tension and was automatically energised when the tension was less than required. The clutch warning light would illuminate whenever the clutch actuator circuit was activated. The Aircraft Flight Manual included a note regarding the clutch in Section 3, Emergency Procedures. The note stated that stretching of the belts often resulted in illumination of the clutch warning light for brief periods as the drive actuator readjusted belt tension. The note also included actions that the pilot should take after 7 or 8 seconds of illumination of the clutch light. One of those actions was to pull the clutch circuit breaker.

The helicopter was fitted with a Pointer (TSO-C91A) Model 3000-10 emergency locator transmitter (ELT). The unit was located on the left side of the rear fuselage.

The total flight time from Roma until the time of the occurrence was about 1 hour 35 minutes. Assuming a fuel usage rate of 60 L per hour, approximately 95 L would have been consumed during that time. On that basis, approximately 95 L should have remained at the time of the occurrence.

Wreckage information

opposite to the helicopter's direction of travel at impact. The impact severely crushed most of the cabin area and deformed the fuselage and tail boom structures.
Two distinct main rotor blade impact marks on the ground forward and to the right of the initial nose impact position, and the damage to the main rotor blades, indicated that the rotor blades were being driven by the engine at impact. The tail-rotor system was intact and there was no evidence that the fuselage was yawing at impact. There was no indication that the helicopter had struck any of the trees in the vicinity of the impact site.

The left fuel tank ruptured during the impact sequence and was empty. The right fuel tank was also empty. With the helicopter lying on its left side, the right fuel tank vent line was at the lowest part of the tank and would have allowed fuel to drain out. There was a strong smell of Avgas in the vicinity of the wreckage on the day after the accident.

The hydraulic system switch was found in the ON position.

Instrument panel light globe and instrument examination confirmed that electrical power was available to the instruments. There was no evidence of malfunction of any of the instruments.

The six warning lights at the top of the centre pedestal were destroyed by impact forces, preventing an assessment being made of their status at impact. The eight warning lights at the top of the flight instrument panel were intact. Examination of those light globes revealed stretching of the clutch warning light filament. Stretching indicates that the filament was hot and that electrical power was applied to the globe when it was subject to forces during the impact sequence. It was not possible to determine the length of time that the globe had been illuminated. Filament stretch was not evident in any of the other seven warning light globes from the top of the instrument panel.

Damage to the landing light globes prevented any assessment being made regarding their status at the time of the occurrence. The damage to the landing light switch indicated that it was in the ON position at impact.

The circuit breaker panel was destroyed by impact forces. The clutch actuator fuse was serviceable. The wreckage examination did not reveal any fault in the clutch system. Although the circuit breaker panel was destroyed, the evidence of electrical power to the clutch warning light indicates that the circuit breaker was engaged, and therefore the system was powered at the time.

The coaxial cable from the ELT unit to the external antenna had separated at the connector to the antenna base on the inside of the antenna mounting panel. The separation of the coaxial cable trapped the transmitted signal within the fuselage compartment. That rendered the ELT unit ineffective and prevented satellite detection of the signal. The separation of the cable appeared to have been as a result of impact forces. As a result, the search and rescue effort was significantly affected.

Specialist examination of the ELT revealed that it had activated upon impact and, when connected to a suitable antenna, was capable of transmitting a normal signal.

The engine was test run after removal from the wreckage and operated normally. The hydraulic pump and three hydraulic servos that formed part of the main rotor flight control system were removed from the wreckage for functional testing. The tests were conducted at the helicopter manufacturer's facility in the USA and supervised on behalf of the ATSB by a representative from the US National Transportation Safety Board. The tests confirmed that the hydraulic system components met the specifications for normal operation.

Meteorological information

Documents found in the helicopter included an Area 41 weather forecast valid from 0900 to 2100 on the day of the occurrence and the Roma terminal area forecast (TAF) valid from 1200 to 2400 on the day of the occurrence.

The area forecast indicated that the weather in the vicinity of Eurella Station would include areas of rain with locally moderate falls, scattered showers and isolated thunderstorms. The Roma TAF indicated that between 1500 and 2400 there would be 60 minute periods in which the visibility would be 2 km in heavy rain, with broken cloud² at 700 ft.

An analysis by the Bureau of Meteorology indicated that during the late afternoon on the day of the occurrence, a surface trough was located from Camooweal to St George, with cold south-west winds to its west and northerlies to its east. The surface trough combined with an upper level trough over the southwest of the state to bring a large cloud band with widespread rain and isolated thunderstorms to the interior. The analysis of satellite imagery and synoptic reports, concluded that there was a high probability of rain in the Eurella Station area around the time of the occurrence, and most likely greater than 5 oktas of cloud cover. However, because the nearest weather radar station was about 200 km distant at Charleville, the amount of cloud cover in the area of the occurrence could not be confirmed.

Persons at and near Eurella Station variously reported that the weather conditions during the day of the accident were windy, with heavy cloud and showers.

Astronomical information

According to information published on the Geoscience Australia website, sunset and twilight times at Eurella Station on the day of the occurrence were:

Sunset 1757³
Civil Twilight 1820⁴

Other information on the website indicated that the moon set at 1409 and was 79 degrees 31 seconds below the horizon at 1830 that evening.

Helicopter night VFR

The pilot's night VFR (helicopter) rating authorised him to act as pilot in command of private or aerial work flights at night under the VFR. Once issued, a night VFR rating remained permanently valid. To exercise the privileges of the rating, a pilot needed to complete a 1-hour night flight during the previous 12 months and one take-off and landing at night during the previous 6 months. There was no requirement for the holder of a night VFR rating to have any recent instrument flight time prior to conducting a flight at night.

A pilot operating under the VFR at night was required to operate in visual meteorological conditions that included a minimum of 5 km visibility. The Aircraft Flight Manual, Section 2, Limitations, included the following statements:

VFR operation at night is permitted when landing, instrument, and anti-collision lights are operational. Orientation during night flight must be maintained by visual reference to ground objects illuminated solely by lights on the ground or adequate celestial illumination.

At the time of the occurrence there was a 1,000 watt flood light on each of the northern and western walls of Eurella homestead, as well as lights in other buildings. However, there were many trees in the vicinity of the homestead, some of which were higher than the homestead roof. Depending on the altitude and position of the helicopter, the trees could have prevented those lights being seen from the helicopter (Figure 1). There was no other lighting in the general area, including at the airstrip adjacent to the homestead. The homestead lights, in effect, formed a 'point' source of light.

Spatial Disorientation

Spatial disorientation refers to a situation in flight in which the pilot fails to sense correctly the position, motion or attitude of the aircraft. When the condition is fully developed, the pilot is unable to tell which way is 'up'.

The risks of non-instrument rated pilots flying in conditions in which they are not able to orientate the aircraft by visual reference have been well known for over 50 years. During testing conducted on a group of non-instrument rated pilots, the average time before loss of control of the aeroplane, after visual reference was lost, was 178 seconds.⁵

US FAA Advisory Circular 60-4A, Pilot's Spatial Disorientation, was published in 1983 and was intended to inform pilots of the hazards associated with disorientation caused by loss of visual reference with the external environment. It included the following information:

Tests conducted with qualified instrument pilots indicate that it can take as much as 35 seconds to establish full control by instruments after the loss of visual reference with the surface.

The helicopter manufacturer issued a safety alert and safety notices (SN) as a result of various occurrences and incidents, and included those notices in the Aircraft Flight Manual Section 10, Safety Tips. Two of the notices related to night flight - SN-18 Loss of Visibility Can Be Fatal, and SN-26 Night Flight Plus Bad Weather Can Be Deadly (see Appendix A). Safety notice SN-18 stated in part:

Helicopters have less inherent stability and much faster roll and pitch rates than airplanes. Loss of the pilot's outside visual references, even for a moment, can result in disorientation, wrong control inputs, and an uncontrolled crash.

Appendix A

On 8 September 2004, the owner/pilot of a Robinson Helicopter Company R44 Raven II helicopter, registered VH-JWX, conducted a private flight under the visual flight rules (VFR) from Coffs Harbour, NSW to Eurella Station, Qld. The flight included a landing at Roma, Qld where the pilot refuelled the helicopter with 180 L of Avgas from the bulk underground fuel storage supply. The pilot then continued to Eurella Station, located approximately 54 km west of Roma, arriving at 1705 Eastern Standard Time. The pilot shut down the engine and the property owner boarded the helicopter for a pre-arranged local flight. The pilot made several attempts to start the engine, during which it backfired a few times. Once started, the engine seemed to function normally.