Collision with terrain

FACTUAL INFORMATION

History of the flight

At approximately 0910 EST, the aircraft took off from runway 32 at Horn Island and commenced a normal climb. Shortly after, it adopted a nose-high attitude and commenced a wingover type manoeuvre to the right. Witnesses described the aircraft as being in a nose-low attitude, and at a height of approximately 600 ft to 700 ft above ground level after the completion of this manoeuvre. It then abruptly adopted a level attitude and rapidly entered a spin to the left.

Witnesses on the ground reported that at approximately the same time as the aircraft entered the spin, engine power became asymmetric, with the right engine continuing to deliver considerable power. The aircraft continued to descend in a fully developed flat spin, with no observed signs of an attempt to recover. The impact was heard shortly after the aircraft descended behind vegetation to the north-west of the aerodrome. The accident was reported to Flight Service by radio at 0918.

The wreckage was located on a beach approximately 2 km to the north-west of the aerodrome. The aircraft was destroyed by impact forces and the pilot sustained fatal injuries.

Wreckage examination

Examination of the wreckage indicated that the aircraft had impacted the ground in an almost flat attitude while rotating in an anticlockwise direction.

Examination of the airframe and flight control systems did not reveal any pre-impact malfunction or defect which may have contributed to the accident.

Damage to the right engine, and propeller blade slash marks on the trunks of trees at the accident site, indicated that the right engine was producing considerable power at impact. The left propeller was in the feathered position. The left engine and propeller were removed from the wreckage for further examination. There was no evidence of pre-existing defects. Subsequent tests determined that the engine was capable of producing power prior to impact.

Maintenance history

A review of the aircraft, engine and propeller logbooks found nothing to suggest any irregularity that was likely to have affected the normal operation of the aircraft during this flight.

Pilot information

The pilot was the holder of an Australian commercial pilot licence for aeroplanes.  He held a valid medical certificate, multi-engine command instrument rating and grade one instructor rating. At the time of the accident, he was the chief flying instructor for the company's flying school and carried out check-and-training duties for the company's charter operations. He had accumulated approximately 11,740 flying hours, of which 7,750 hours were acting as pilot in command of multi-engine aircraft.

The pilot was endorsed on the Aero Commander 500S on 15 October 1993 and had accumulated in excess of 119 hours on type. He had flown the accident aircraft on a number of occasions.

Results of the post-mortem and toxicological examination of the pilot did not indicate signs of incapacitation due to a medical condition or the presence of drugs or alcohol.

A review of the pilot's activities in the 72 hours prior to the accident established that he had been flying for another company in Cairns during the previous weekend. He had a late night on Sunday and was observed to consume a considerable amount of alcohol and smoke heavily on this occasion, activities which he reportedly had not engaged in for some time. He was described as in good spirits on Monday morning and departed for Horn Island during the afternoon. Monday evening was spent with other company employees at the local motel. During this period, he was not observed to consume alcohol. He returned to the company's accommodation on the island with one of the company pilots. They spent a short time talking before retiring at approximately 2200.

On the morning of the accident, the pilot was rostered to train one of the company pilots on the Aero Commander 500. After arriving at the airport by bus at approximately 0900 EST, he was observed to walk through the terminal and proceed directly to the aircraft. He was not wearing his uniform. Shortly after, the pilot was observed to start the engines of the aircraft and taxi to the runway holding point. Witnesses reported that they did not observe the pilot carry out a pre-flight inspection of the aircraft or any pre-take off engine checks.

Weather

At the time of the accident the wind was a light south-easterly and there was scattered cloud with a base of approximately 1,800 ft. The weather was not considered a factor in this occurrence.

ANALYSIS

The investigation established that the aircraft was capable of normal operation prior to impact. No evidence was found to indicate that the performance of the pilot was affected by any physiological condition which may have adversely influenced his ability to carry out his tasks.

As a result of discussions with a number of witnesses and friends of the pilot, it is apparent that his behaviour immediately prior to the accident was not in keeping with what most described as his thorough and professional attitude to aviation. Witnesses and friends also stated that they had never known the pilot to commence a flight when not wearing his uniform and without having carried out a pre-flight inspection of the aircraft or any pre-take-off engine checks.

The aircraft entered a flat spin at a height from which recovery may have been possible. The reason the aircraft entered the spin and subsequently crashed could not be determined.

CONCLUSIONS

Findings

1. The pilot held a valid pilot licence and medical certificate.
2. The pilot was endorsed on the aircraft type.
3. The aircraft entered a flat spin to the left with no reported signs of an attempt to recover.
4. The aircraft struck the ground whilst established in a flat left spin.
5. The right engine was producing considerable power prior to impact.
6. Indications were that the left engine was producing little or no power. Its propeller was in the feathered position prior to impact.
7. No evidence was found to indicate a malfunction or pre-existing defect with the aircraft or its systems which may have affected normal operation during this flight.
8. No evidence was found to indicate pilot incapacitation as the result of a medical condition or the presence of alcohol or drugs.
9. The pilot's behaviour on the morning of the accident was not consistent with what was generally accepted to be a thorough and professional attitude to aviation.

The crews of two helicopters had been engaged in survey work. On the morning of the accident, the second helicopter became unserviceable. The pilot and passenger, in conjunction with the pilot of the grounded helicopter, decided to continue on their own. About 45 minutes after commencing the flight, the helicopter flew up a dry creek line and struck a high-voltage single wire powerline. The line severed the flying controls at the mast. All control was then lost and the helicopter crashed into the dry creek bed.

When electrical power was lost at the cattle station homestead, search parties were sent in both directions along the powerline. The wreckage of the helicopter was found about 45 minutes after the power was lost.

The span of the SWER (single wire earth return) line struck by the helicopter was 490 m and was strung between two hilltops. The point of impact was approximately 40 m above the creek bed and about 20 m above the general tree canopy. This was the pilot's second day at the station. He was not familiar with the area south of the homestead which included the crash site.

Significant factors

The following factors were considered relevant to the development of the accident:

1. The pilot was flying the helicopter at low level in a survey/mustering operation.
2. The second helicopter which had been used for lookout duties was unserviceable.
3. The pilot was unfamiliar with the area.
4. He did not see the SWER line in time to avoid a collision.
5. Control of the helicopter was lost when the wire cut control rods.

1. FACTUAL INFORMATION

1.1 History of the flight

The pilot had commenced mustering at Kilclooney Station at about 0700 EST. A refuelling stop was made at about 0930 when the mustering operation had been completed. After refuelling, the pilot took off and returned to the homestead, which was about 5 minutes flying time away, intending to collect his swag and the helicopter canopy cover and then return to his home base at Greenvale, 76 km west of Kilclooney. The pilot phoned his wife at about 1045 to say he was departing Kilclooney. At about 1050 the power supply to the homestead failed. The homestead was unattended at the time. At 1330 the company chief pilot reported to Brisbane Search and Rescue (SAR) the aircraft had not arrived at Greenvale. At 1348 the Brisbane Area Approach Control Centre (AACC) co-ordinator advised SAR that an emergency locator transmitter (ELT) signal had been heard by an overflying aircraft. The Queensland Emergency Services helicopter was then tasked to conduct a search in the area where the beacon was heard. At 1506 the wreckage of the helicopter was located at Kilclooney Station.

The helicopter had collided with a single 19-kilovolt powerline located near where the helicopter had been parked overnight. He had apparently landed near the homestead, to collect the swag which was known to be on the back of a vehicle, and then repositioned the helicopter to the parking area to pick up the canopy cover.  Two parallel wires

15 metres apart were strung from poles near the homestead and passed alongside the parking area in a southeast-northwest direction.

1.2 Impact information

It is probable that as the helicopter was approaching the parking area from the south, the left skid passed under the second wire which had a span of approximately 150 metres. The helicopter travelled a short distance before impacting the ground in a steep nose-down attitude and caught fire. The three-strand 12-gauge steel wire did not break and was trapped under tension by the wreckage for some time. The left skid was thrown clear of the fire when it became detached by heat and the wire separated from the wreckage. The wire was substantially stretched and was within 4 metres above ground level after becoming detached from the wreckage.

1.3 Pilot in command

The pilot was correctly licensed and endorsed and appeared to be in good health immediately prior the accident.

1.4 Meteorological information

Station personnel reported that the weather was fine with a moderate northerly wind at the time of the accident.

1.5 Wreckage examination

The cabin area forward of the firewall was completely destroyed by fire. The engine suffered substantial fire damage, and all engine accessories were damaged beyond the point where the serviceability of these items could be assessed. The ELT was a fixed installation in the engine bay and was destroyed by fire, it was of the type that complied with TSO C91. No mechanical failures or defects were discovered with the engine which would have prevented it from operating normally. The tail boom was separated from the main wreckage and remained clear of the fire. The tail rotor and tail rotor gearbox appeared undamaged, indicating that a steep nose-down impact had occurred.

2. ANALYSIS

The wind direction would have required an into-wind approach to be made over two wires which were about 15 metres apart. The approach over the second wire would have to be steep to achieve a touchdown near the fuel drum where the canopy cover was located and would therefore have taken the helicopter close to the second wire. During the accident sequence the helicopter actually struck the drum. Why the helicopter struck the wire could not be determined, but it is probable that the helicopter was capable of normal operation up to the time of the accident. The canopy cover was on the ground beneath an upright 200-litre fuel drum, located about 10 metres from the powerline. The helicopter was probably previously parked in this particular position as the pilot did not want to frighten horses in an adjacent paddock.

3. CONCLUSIONS

3.1 Findings

1. The pilot was correctly licensed and fit to perform the flight.
2. There were no mechanical defects discovered which may have contributed to the accident.
3. The helicopter had been previously parked in close proximity to a single strand powerline and was being manoeuvred to land at this position to allow the pilot to collect the helicopter canopy cover.
4. The wind direction required an approach from south to north over the top of the powerline.
5. The helicopter struck the powerline.

3.2 Significant factors

1. The aircraft was being manoeuvred in close proximity to a single-wire powerline.
2. The pilot failed to see and avoid the powerline.

1. FACTUAL INFORMATION

1.1 Sequence of events

The aircraft was on a powerline inspection flight. It was crewed by a pilot employed by the operator of the aircraft and by an observer from the power supply company. The purpose of the flight was to enable the observer to identify obstructions in the form of trees and branches potentially too close to the powerlines and constituting a fire hazard, and to assess the condition of the conductor and associated items.

To enable the observer to inspect a powerline such aircraft are flown 150 feet above ground level, at 70 knots, with flaps extended 10 degrees. The aircraft is tracked down the left side of the powerline to give the observer in the right seat a good view of the line.

Shortly before the aircraft crashed, it was observed flying along a spurline. It was at this time flying essentially downwind. Some minutes later, the wife of a nearby farmer who had been listening to the approaching aircraft realised that she could no longer hear the engine. Her husband located the wrecked aircraft in a paddock and initiated an emergency response. There were no witnesses to the accident. Neither the pilot nor the observer survived the impact.

1.2 Wreckage and impact information

The aircraft had impacted the ground in a nose-down attitude of approximately 45 degrees. The right wing was down approximately 30 degrees relative to the horizon. The wreckage trail was short, indicative of low forward speed at impact. The disposition of the wreckage indicated that the aircraft had been rotating to the right before impact.

Wreckage analysis disclosed no pre-impact faults. The aircraft had sufficient fuel for the flight and had been properly maintained. There were no pre-existing defects recorded on the maintenance release. The pilot had updated personal, company and aircraft records at the completion of the previous day's flying.

1.3 Pilot details

The pilot commenced flying training in 1987. He obtained his commercial pilot licence in December 1991, an instructor rating in May 1992, and a command instrument rating in July 1993. His logbook recorded that while flying as an instructor he had instructed student pilots on the causes of stalling and on stall recovery techniques. He had flown a total of 1,276 hours.

He commenced his training in powerline inspection flying techniques on 19 July 1994. After eight hours instruction over five flights, he was assessed as having met the required standard. Accordingly, he was approved to conduct powerline inspection flying for a period of 12 months. At the time of the accident, he had conducted 209 powerline inspection flights totalling 462 hours. The latest check for revalidation of his powerline inspection flying approval, carried out on 13 July 1995, was valid for one year and was therefore valid at the time of the accident.

The pilot had ferried the aircraft from Moorabbin to Hamilton three days prior to the accident. Including the ferry time, he had flown for four hours, two hours and three hours respectively, on the three days prior to the accident. On the day of the accident, he flew for just under three hours. The aircraft was one of two that were conducting powerline inspections out of Hamilton aerodrome. The pilot of the second aircraft advised that the crews had a quiet night and were well rested before commencing the day's operation.

The pilot held a valid medical certificate. The post-mortem examination did not disclose any medical factors that may have contributed to the accident.

1.4 Meteorological information

The property owner advised that the weather at the time of the accident was fine with a light breeze from the northwest. This was consistent with the forecast issued by the Bureau of Meteorology which had predicted a 15-knot breeze for the area. Weather was not considered to have been a factor in the accident.

1.5 Roll and cut manoeuvre

If an observer does not get a clear view of an obstruction, then the aircraft is required to fly a specific manoeuvre to give the observer a better view. The manoeuvre is called a 'roll and cut'. When the aircraft is flying on the left of the line and the observer calls 'roll' the pilot rolls the aircraft to the right to cross the powerline at 45 degrees. This enables the observer to look back down the line at the obstruction. If after crossing the line, the observer requires a further look at the obstruction, he calls 'cut'. The pilot then continues the right turn until the aircraft has turned through 270 degrees from the original heading. The aircraft is then rolled wings-level to cross the line at right angles, giving the observer a clear view of the obstruction to the right as the aircraft passes over the line. After crossing the line, a 270-degree left turn is made to re-position the aircraft to continue the inspection.

The wreckage was located in a paddock with the wreckage trail aligned nearly at right angles to and under the powerline that was being inspected. In the paddock there was one line of scrub before the accident site and one tree after the accident site that might have been subject to a cut and roll inspection manoeuvre. Due to the lack of witnesses to the accident the investigation was unable to determine what manoeuvre was being carried out prior to the loss of control which preceded the accident.

The power supply company advised that in the year before the accident, some 56,000 km of line was patrolled, finding 27,514 trees that needed attention. This would mean that to verify the hazard, at the very least one cut and roll is required for approximately every two kilometres flown.

1.6 Powerline inspection: flight parameters

The aircraft operator and the power supply company determined the optimum height for inspection of powerlines to be 150 feet above ground level and the optimum speed to be 70 knots. It is the pilot’s responsibility to maintain these parameters. The height of the power poles varies between 25 feet and 40 feet. There was evidence that, on occasions, powerline inspection aircraft had been observed to fly lower than 150 feet. Some pilots had commented that occasionally the observers asked for the aircraft to be flown at a lower height. The pilots considered that this might have been due to difficulty observing powerlines in certain conditions of sun and light and to the difference in visual acuity between individual observers. The power supply company did not have standards for, and did not require a check of, the observer's visual acuity. When the observer completed his training two years before the accident his visual acuity was obviously acceptable. However, there was no ongoing program to check and detect any deterioration that may have occurred since that time.

1.7 In-flight incapacitation

Post-mortem examination disclosed that the observer suffered from asthma and had advanced heart degeneration.

Microscopic examination of his lungs showed changes in keeping with asthma. However, no macroscopic findings were seen that would have indicated he had suffered a severe asthma attack.

The post-mortem examination showed significant coronary artery disease with a 75 per cent stenosis of the left anterior descending coronary artery. Expert pathological opinion was that an individual with significant coronary artery disease may have an episode of myocardial ischemia leading to severe pain or change in conscious state. However, the physical reaction could be expected to be benign, resulting in slumping of the body. The observers sit with the seat at the limit of its aft travel to enable them to use their maps clear of interference with the control column and to give the best view through the right window. It is unlikely that control interference would occur due to a body slumping while the seat was in the aft position. It could not be determined if the observer suffered any form of incapacitation in the period immediately before the accident.

Neither the observer's family nor his employer was aware of his medical condition. The employer did not require the observers to meet a minimum medical standard.

1.8 Flight path simulation

A flight was undertaken to simulate the inspection of the spur line that was being inspected immediately prior to the accident. The flight was conducted by the operator's manager of powerline flying and conformed to the required parameters of height, speed, and configuration. The flight was watched by some persons who saw the accident flight, shortly before the accident, and by some who had watched other powerline inspection flights. They said that they had seen many flights, including the accident flight, operated either more slowly and/or at a lower height and/or with greater bank angles, than those demonstrated during the simulation flight.

2. ANALYSIS

The accident probably occurred when control of the aircraft was lost while it was flying at a height too low for the pilot to apply effective stall/spin recovery techniques. The sequence of events that led to the loss of control could not be established because there were no witnesses to the maneouvres that preceded the accident. However, there was evidence that some powerline inspection flights had not complied with the operator's height, speed, and angle of bank requirements. This may indicate that some of the pilots had become complacent and had a lowered awareness of the dangers of flying low and slow and lacked appreciation of the importance of strictly adhering to the operator's flight parameters.

Although the observer was suffering from a medical condition which may have led to his becoming disabled, there was no evidence that this had occurred. Had an episode occurred it could have resulted in severe pain or collapse. Either could well have been distracting to the pilot. It is unlikely that the onset would have been of such severity as to cause involuntary limb and body movements that may have interfered with the flight controls, leading to loss of control of the aircraft.

3. CONCLUSIONS

3.1 Findings

1. The aircraft was properly certificated and maintained, held sufficient fuel for the flight, and was serviceable at the start of the flight.
2. The pilot was properly licensed and had been properly trained and checked for conducting low-level powerline flights.
3. Some powerline inspection flights had been observed to deviate from the required flight parameters.
4. The power supply company did not have minimum medical standards for its observers.
5. The observer had a medical condition that may have incapacitated him.

3.2 Significant factor

1. Control of the aircraft was lost at a height from which the pilot was unable to recover.

4. SAFETY ACTION

4.1 Immediately after the accident the power supply company suspended flying and, with the operator, assisted in the conduct of the investigation. When it became apparent that the operator's flight parameters were not always being observed, the operator instituted a campaign to improve pilot awareness and discipline. When flying recommenced, the observers advised that there was a marked difference in the way the pilots manoeuvred the aircraft.

4.2 Both the powerline company and the aircraft operator conducted a major reassessment of the operation. They have decided to:

(a) fit four-piece crew restraint harnesses to all aircraft;

(b) supply crash helmets for both the pilots and observers, and require that they be worn;

(c) require observers to meet a minimum medical standard; and

(d) initiate crew resource management training for pilots and observers, with emphasis on safety awareness.

4.3 Before the accident the operator and power supply company commenced experimenting with the use of differential video imaging and infra-red detectors to aid in the identification of hazardous trees. When implemented, this system is expected to reduce the need for continuous roll and cut manoeuvres. The optimum height above ground level for this system has been determined to be approximately 250 feet which should improve the margin of safety.

1. FACTUAL INFORMATION

1.1 History of the flight

The pilot planned a private business flight under visual flight rules (VFR).  He took off from Moorabbin shortly after 0800 EST and collected two passengers from Melbourne Airport prior to flying to Warrnambool.   After working in the Warrnambool area during the day, he took off from runway 31 at about 1948 EST.  Conditions in the circuit area were very dark with limited ground lighting, high overcast cloud, some low cloud, and patches of drizzle.

The complete flight path after take-off is unknown.  However, witnesses heard and saw the aircraft flying low to the north-west and west not far from the aerodrome.  The last sighting was of the aircraft climbing to the east-south-east towards the centre of runway 31, followed by a left turn and a steep left spiral dive from an estimated height of about 500 feet.  At 1950 the aircraft crashed 255 metres to the right of runway 31 centreline. Runway 31/13 lights were illuminated at the time.

At impact the fuel cells burst.  There was a flash fire along the wreckage trail.  However, most of the fire damage was confined to the detached wings.

1.2 Damage to aircraft

The aircraft was destroyed by the ground impact and by post-impact fire.

1.3 Weight and balance

The aircraft weight and balance were within approved limits for the flight.

1.4 Personnel information

The 54 year old pilot was correctly qualified and endorsed to perform the flight.  He held a private pilot licence (aeroplanes) and a single-engine night rating valid for automatic direction-finding equipment and very high frequency omni-directional radio range.  The night rating was issued on 11 October 1994.  His total night flying experience was 22.3 hours.  This comprised 13.3 hours dual flight instruction in a Piper PA28, a 3.3 hours flight test in a PA28 with an approved testing officer, and 5.7 hours as pilot in command, of which 2.5 hours were in a PA28 and 3.2 were in the Cessna 182.  His most recent previous night flight occurred on 6 October 1995.  His Civil Aviation Safety Authority medical certificate was valid until 14 August 1997.  He was required to wear spectacles for close vision.

1.5 Meteorological information

A weather observation taken by a trained observer at Warrnambool at 1800 indicated: QNH 1011.6 hectopascals, surface wind 320 degrees 18 knots, visibility 20 kilometres, light rain, cloud 8 octas of altocumulus base at 8,500 feet, temperature 15 degrees Celsius, dew point 15 degrees Celsius.

An observation taken at Warrnambool at 2100 indicated: QNH 1015.5, surface wind 230/10 knots, visibility 50 kilometres, weather nil, cloud 8 octas of altocumulus, base 8,500 feet, temperature 13 degrees Celsius, dew point 15 degrees Celsius.

Charts provided by the Bureau of Meteorology indicate that the accident occurred as the tail end of a cold front was passing through Warrnambool.

Witness evidence of weather at the time of the accident varies.  However, the consensus was that it was very dark because cloud had obscured the moonlight, and that there was intermittent drizzle in the area. Because it was so dark, witness estimates of cloud amount and height varied but indicated that there were patches of cloud below 1,000 feet in the area.

At 1900, before leaving Warrnambool city, the pilot telephoned the Civil Aviation Authority briefing office, and a briefing officer gave him a detailed update on the forecast weather for the proposed flight.  The pilot had already submitted a night visual flight rules flight plan for the return flight to Moorabbin via Avalon.  During the five-minute discussion, the briefing officer advised of the area forecast 30/32, Melbourne aerodrome forecast, and Moorabbin aerodrome forecast.  From the discussion it was apparent that the pilot was fully aware of a weather front passing through Warrnambool at about the time of the telephone call.  He advised the briefing officer that there were some fairly low cloud layers at Warrnambool at the time.  The forecast weather ahead of the front and well behind it was suitable for night visual flying, whereas weather associated with the front included scattered cloud from 1,000 feet to 2,000 feet and visibility reduced to 3,000 metres in drizzle.  He advised the briefing officer that if he could depart Warrnambool quickly, he would be ahead of the trough and that he would telephone the briefing office again to lodge a search-and-rescue time when he was about to depart Warrnambool aerodrome.

The taxi driver who drove the pilot and the two passengers to the aerodrome, arriving at about 1930, advised that as they neared the aerodrome it was a moonlight night, but the clouds were rolling in from the west and starting to obscure the moonlight.

At 1933 the pilot telephoned the briefing office from the aerodrome and lodged a search-and-rescue time of 2130 for arrival at Moorabbin.  The briefing officer advised that Warrnambool was probably still east of the trough/cold front.

1.6 Aids to navigation

Warrnambool has a pilot-monitored non-directional beacon which was transmitting on 395 kilohertz at the time of the accident.

1.7 Communications

Warrnambool has a common traffic advisory frequency of 126.0 megahertz which is not recorded. The common traffic advisory frequency applies for a radius of five nautical miles and up to 3,000 feet above the aerodrome reference point.  Had the pilot flown beyond five nautical miles or above 3,000 feet, he probably would have made a departure call to Melbourne flight service and this call would have been recorded.  The flight service communications tape has since been monitored.  No departure call was recorded.

1.8 Aerodrome information

Warrnambool Airport is 11 kilometres north-west of Warrnambool city.  It has two runways.  Runway 31/13 is the only one with runway lighting installed.  The runway lighting is a pilot-activated system. Because the runway lights were on, it is probable that the pilot of VH-XTK had activated them prior to take-off. Runway 31/13 is 1,372 metres long, 30 metres wide, and the surface is asphalt.  The aerodrome is 242 feet above sea level.  The surrounding terrain varied from relatively flat to gently undulating.

1.9 Wreckage and impact information

The impact site was abeam a position approximately 925 metres along runway 31 and 255 metres to the right of centreline.  At impact the aircraft was an estimated 70 degrees nose down, facing 278 degrees magnetic and left wing low.  Wreckage was spread over 107 metres in the direction of 008 degrees.  The engine was torn out of the airframe and was found four metres from the point of initial impact.  Most of the fuselage came to rest within 58 metres of the initial impact point.  Both of the wings were torn off.

The control system was inspected and the damage sustained was consistent with impact damage. The flaps were up at impact.

The propeller was torn from the engine. A subsequent inspection showed evidence of its being within one degree of full fine pitch at impact.

The engine and its accessories were inspected.  A metallurgist examined the exhaust pipe and confirmed that the engine was producing hot exhaust gases at impact.

The engine-driven vacuum pump was subsequently determined to have been serviceable at impact.  The artificial horizon showed impact evidence of a steep nose-down attitude.  The turn co-ordinator showed evidence of hard left bank at impact.  The altimeter subscale setting was 1013 hectopascals.

Fuel filters were found clean.  The fuel on board was of the correct type and of sufficient quantity for the flight.

No fault was found with the aircraft or its systems that may have contributed to the accident.

The accident was not survivable.

1.10 Medical information

The specialist forensic pathologist who performed the autopsy on the pilot documented the cause of death as multiple injuries.  However, he advised that the presence of ischaemic heart disease in the pilot may have contributed to the accident.

1.11 Emergency locator beacon

The emergency locator beacon did not function correctly after the accident.  The antenna cable was severed at impact. When tested, a low-level signal was received at very close proximity.  The battery was one month past its replacement date, but the voltage was within tolerance.  The negative terminal was corroded, causing a high resistance joint which resulted in low signal strength.

1.12 Spiral dive

Some basic spiral dive trials were subsequently conducted in another Cessna 182R.  With his aircraft at 6,000 feet and trimmed to 100 knots indicated airspeed, 20 inches manifold air pressure and 2,400 revolutions per minute, the pilot closed the throttle and gently banked the aircraft 45 degrees left without applying back pressure on the control yoke to maintain height.  The nose began to drop.  By 100 feet height loss, the vertical speed indicator had reached 500 feet per minute rate of descent.  With 280 feet total height loss, the vertical rate of descent was 1,400 feet per minute. With 450 feet total height loss, the vertical speed indicator needle was on the 2,000 feet per minute descent stop and the indicated airspeed was 125 knots.

A similar exercise was conducted leaving the power at 20 inches manifold air pressure.  In about 200 feet height loss, the vertical rate of descent reached 2,000 feet per minute and the airspeed was about 135 knots and increasing rapidly.

1.13 Pilot training

The pilot's night VFR training was conducted from Moorabbin by a Grade Two instructor.  The training included navigational exercises to Essendon, Latrobe Valley, Bendigo, Ballarat and Mangalore.  In excess of three hours dual night circuit training was conducted at Moorabbin and Latrobe Valley.  The pilot also performed night landings and take-offs at Bendigo, Ballarat and Mangalore.  The Mangalore circuit area was known to contain minimal ground lighting.

The pilot's instructor taught him to take off and fly solely on instruments from the moment the runway lights disappeared from view on take-off until 500 feet above ground level.  From about 500 feet on the crosswind climb, he was taught to fly 75 per cent on instruments and 25 per cent by visual reference; on downwind, 50 per cent on instruments and 50 per cent visual, on base, 25 per cent instruments and 75 per cent visual.  The pilot was given two hours night dual flight instruction practising navigation by reference to navigational aids.  He was also trained in recovery from unusual attitudes at night.  His instructor advised that the pilot displayed good airmanship and a responsible attitude while under training.

During an interview after the accident, the instructor was asked what he thought the pilot would do if at 500 feet after take-off he looked out and found himself in cloud. The instructor replied that he thought the pilot would immediately descend to regain visual flight.

2. ANALYSIS

With pre-flight planning/preparation, early departure from Moorabbin, business meetings through the day and the 1948 EST estimated take-off time from Warrnambool, it is possible that the pilot was suffering from fatigue at the time of the accident.  However, the degree of fatigue and the degree to which it contributed to the accident remains unknown.

It also remains unknown how the onset of darkness and the degree of darkness hampered the pilot's ability to assess the amount and base of the cloud and/or the existence of drizzle in the circuit area immediately before take-off.

It is possible that the pilot first looked out at 500 feet after climbing on instruments and found himself in drizzle or in cloud, with limited or no external visibility. If this happened, it is likely that the pilot immediately descended to become visual and then attempted to return for a landing on runway 31.  This is consistent with witnesses seeing the aircraft flying at low level.

Why the pilot flew towards the centre of runway 31 immediately prior to entering a steep left spiral dive, could not be determined.  Perhaps low cloud or drizzle prevented the pilot from flying further downwind to position for a landing on runway 31, or perhaps he could have been positioning the aircraft for a departure.

As witnesses clearly saw the aircraft climb and then enter the spiral dive, it seems that the aircraft was not in cloud or drizzle for the spiral entry and subsequent descent.

The impact site was only 255 metres to the right of a row of the illuminated runway lights which should have given the pilot a visual reference to avoid the ground. There was no evidence of an attempted recovery from the left spiral dive.

Pilot disorientation is a possible reason for the spiral dive because conditions were dark and there was probably no visible horizon.  However, the aircraft was not in cloud or drizzle for the spiral and the accident occurred close to the illuminated runway, which should have given the pilot a reasonable visual reference to level the wings and attempt to recover from the dive.

It is also possible that the pilot suffered incapacitation during the flight.

3. CONCLUSIONS

3.1 Findings

1. The pilot was correctly qualified and endorsed to perform a night flight under visual flight rules, but his night flying experience level was low.
2. The pilot did not hold an instrument rating.
3. Weather forecasts, assessed by the pilot prior to take-off, indicated that the weather may have been suitable for night visual flight ahead of the cold front trough and behind it.
4. The accident occurred as a cold front was passing through Warrnambool.
5. There was a low cloud cover with associated drizzle in the area.
6. The aircraft was within its approved centre of gravity and gross weight limits at the time of the accident.
7. The fuel on board was of the correct type and of sufficient quantity for the flight.
8. No pre-existing fault was found with the aircraft which may have contributed to the accident.
9. The impact occurred close to and abeam runway 31 while the runway lights were illuminated.
10. The post-mortem carried out on the pilot indicated the presence of ischaemic heart disease may have contributed to the accident.

3.2 Significant factors

The factors which led to this accident could not be positively determined.  However, the three most likely factors are:

1. The pilot was suffering from fatigue at the time of the accident.
2. The pilot suffered some form of in-flight incapacitation.
3. The pilot lost control of the aircraft as a result of losing visual reference in adverse weather.

SAFETY ACTION

The Bureau of Air Safety Investigation is continuing to investigate a number of possible safety deficiencies in the operations area that have arisen from this accident. Any safety outputs arising from this investigation will be published in the Quarterly Safety Deficiency Report.

The flight was the second Metro III type-conversion training flight for the co-pilot. Earlier that night, he had completed a 48-minute flight.

During the briefing prior to the second flight, the check-and-training pilot indicated that he would give the co-pilot a V1 cut during the take-off. The co-pilot questioned the legality of conducting the procedure at night. The check-and-training pilot indicated that it was not illegal because the company operations manual had been amended to permit the procedure. The crew then proceeded to brief the instrument approach which was to be flown following the V1 cut. There was no detailed discussion concerning the technique for flying a V1 cut.

The co-pilot conducted the take-off. Four seconds after the aircraft became airborne, the check-and-training pilot retarded the left engine power lever to flight-idle. The landing gear was selected up 11 seconds later. After a further 20 seconds, the aircraft struck the crown of a tree and then the ground about 350 m beyond the upwind end of the runway and 210 m left of the extended centreline. It caught fire and was destroyed. The co-pilot and another trainee on board the aircraft were killed while the check-and-training pilot received serious injuries.

The investigation found that the performance of the aircraft was adversely affected by:

• the control inputs of the co-pilot; and
• the period the landing gear remained extended after the simulated engine failure.

The check-and-training pilot had flown night V1 cut procedures in a Metro III flight simulator, but had not flown the procedure in the aircraft at night. He did not terminate the exercise, despite indications that the aircraft was not maintaining V2 and that it was descending. There were few external visual cues available to the crew in the prevailing dark-night conditions. This affected their ability to maintain awareness of the aircraft's position and performance as the flight progressed.

A number of organisational factors were identified which influenced the aviation environment in which the flight operated. These included, on the part of the operating company:

• an inadequate Metro III endorsement training syllabus in the company operations manual;
• inadequate assessment of the risks involved in night V1 cuts; and
• assigning the check-and-training pilot a task for which he did not possess adequate experience, knowledge, or skills.

Organisational factors involving the regulator included:

• a lack of enabling legislation prohibiting low-level night asymmetric operations;
• deficient requirements for co-pilot conversion training;
• inadequate advice given to the operator concerning night asymmetric operations and the carriage of additional trainees on training flights;
• deficient training and approval process for check-and-training pilots; and
• insufficient quality control of the company operations manual.

The investigation also determined that there was incomplete understanding within the company, the regulating authority, and some sections of the aviation industry of the possible effects of engine flight-idle torque on aircraft performance. Inadequate information on the matter in the aircraft flight manual contributed to this.

Witnesses reported seeing the aircraft depart runway 28 and complete a full circuit without landing. At a height of approximately 400 to 500 ft above ground level as the aircraft was turning onto final approach during its second circuit, it entered a steep nose down spiral to the right. The spiral descent continued to the ground and the pilot received fatal injuries during the impact. The wind at the time of the accident was reported to have been from the north-north-west gusting to 45 km/h.

An unregistered single-seat Sapphire ultralight aircraft took off from the town airstrip at 1700 EST. The pilot had borrowed the aircraft from the owner who expected him to practise flying the aircraft in the vicinity of a private airstrip at the outskirts of the town. At 1720 the aircraft crashed within 2 km of the town airstrip and about 500 m from the private airstrip.

This aircraft was unique. The designer had built it during the developmental stage of the aircraft type. Since then, it had been significantly modified including being retrofitted with a 40 horsepower Rotax 447 two-stroke engine, mounted upright. This is in contrast to the current Sapphire model which has the same Rotax engine installed inverted. The engine mounts were modified to enable the engine to be installed upright, and a specially designed engine cowl had been fitted. The shape of the engine cowl may have affected the aerodynamics of the aircraft.

Even though the propeller reduction gearbox had been installed inverted, the propeller thrust line was slightly higher than in the current model. The higher thrust line may have caused handling differences compared with the current model. The aircraft was fitted with a larger diameter propeller which rotated at lower RPM than propellers installed on current Sapphire models due to different gearing in the reduction gearbox. Whether the thrust produced was the same as the current model is unknown.

This aircraft did not have flaps and was fitted with full-span ailerons. Later Sapphire models have flaps and half-span ailerons. According to the current manufacturer, the full-span ailerons would have had a significant effect on the tendency for spin entry if the pilot inadvertently used aileron, in lieu of rudder, in an attempt to counteract wing drop. The main wing was fully fibreglass covered and appeared to be the same size and shape as the current model. The aircraft was equipped with a vacuum-driven airspeed indicator (ASI) sourced from a small venturi mounted on the nose of the aircraft. The owner had previously tested this ASI in flight and noted that it indicated 35 kts at the stall. Current Sapphires are fitted with a standard pitot/static system and the stall occurs at 36 kts.

The owner stated that when he test flew the aircraft it maintained straight and level flight, hands and feet off the controls, at 65 kts indicated airspeed. However, the effect of any differences between the accident aircraft and the current-model Sapphire concerning tendency to spin, spin entry, the established spin, or spin recovery is unknown.

The owner and the pilot had only flown this modified version of the Sapphire. The owner had a total flying experience of 80 hours in ultralight aircraft, with about 8 hours recent flying experience in the modified Sapphire. He stated that he had discussed the attributes of his Sapphire with the pilot before allowing him to fly it.

Witnesses saw the right wing drop and the aircraft enter a spin at a height estimated to have been between 200 ft and 500 ft. They heard the engine continue to operate until ground impact. One witness stated that the aircraft entered the spin from straight and level flight and spun three times before impact. Another witness stated that the aircraft may have just commenced a slight climb to the right when the right wing dropped and spinning commenced.

At the time of the accident the temperature was about 10 degrees C, the wind was a north-westerly at about 5 kts, and visibility was good with no sun glare because of high cloud cover. Official last light was 11 minutes after the time of the accident. The surrounding terrain was an obstruction-free mud flat.

There was adequate fuel on board and examination of the airframe and the engine found no defects which may have contributed to the accident.

The aircraft's centre of gravity and gross weight at the time of the accident are unknown. The owner and the pilot were unaware of the aircraft's empty weight and centre of gravity prior to the accident flight. Despite this lack of knowledge, pilots had successfully flown the aircraft for about 10 hours since it was modified.

According to other Sapphire pilots, the aircraft type does not exhibit a pre-stall buffet which would warn the pilot of an imminent stall. The Sapphire is not fitted with a stall warning horn. The investigation found that the pilot was wearing large boots and that the very small rudder pedals were located in a confined area of the cockpit pod. This may have made rudder application difficult. Spin recovery was probably not achievable if spin entry was as low to the ground as reported.

The pilot regularly flew his privately owned Jeep ultralight aircraft. Compared with a Sapphire, the Jeep has high drag, a slower cruise speed and a much slower stall speed. The pilot's logbook contained no entries for past Sapphire flights. However, according to the aircraft owner, the pilot had flown this aircraft four times and had accrued about two hours in it before the accident. None of the pilot's logbook entries indicated spin recovery training.

Spinning is currently banned in ultralight aircraft. However, the Australian Ultralight Federation's pilot ground training theory syllabus includes stall and spin recovery procedures, and the inflight stall training syllabus includes recovery from wing drops.

The Sapphire is known to be more sensitive to fly than the Jeep or similar high drag ultralights. It stalls at a higher airspeed and has sensitive handling characteristics. In the stall, the Sapphire normally mushes and then starts oscillating, but it may drop a wing and enter a stable spin. To stop the spin, a pilot must apply standard spin recovery drill. The manufacturer likens Sapphire handling characteristics to a modern glider. He recommends that, before flying a Sapphire, pilots should experience three hours dual instructional flying, including full spin recovery, in a two-place glider, or undertake equivalent training in powered aircraft.

The modified Sapphire stalled and entered a spin at a low altitude from which recovery was not considered possible. The reason the aircraft entered a spin could not be determined.

SAFETY ACTION

On 14 July 1995, the Australian Ultralight Federation (AUF) issued an Operations Bulletin to all training schools requesting them to ensure that the flight training syllabus coverage of stalling is followed. During routine inspections of operators, the AUF is ensuring that this is done.

The Operations Bulletin also requested instructors to impress upon students the need to undergo additional training when upgrading to a higher-performance aircraft. The aircraft manufacturer recommends three hours dual instruction in a glider prior to upgrading to the Sapphire.

Sequence of Events

At about 1000 EST, the pilot and passenger departed from the airstrip at Carrara where the helicopter is normally hangered. From information supplied by persons who knew the pilot, it appears likely that he flew to a remote section of the New England Ranges west of the Clarence River.

At about 1524 three people were mustering cattle just south of an 11,000-V powerline spanning the Clarence River. They saw a helicopter approach from the south and stopped to watch it fly out of sight to the north-west following the course of the river. Moments later, one of them heard the sound of a crash. Upon investigation they found the high-voltage powerline was down and saw parts of the helicopter in the river.

The investigation found that the helicopter had struck and severed the lowest of three high voltage wires spanning the river. The top surface of one main rotor blade had impacted the wire before the wire became entangled in the tail rotor. The evidence indicated that the helicopter started to break apart before impact with the water. The three-phase powerline had a span of 428 metres which drooped to 87 ft at its lowest point over the river. The powerline sloped from the western bank to a much lower bank east of the river. Both supports were obscured by trees when viewed from the south-east at low altitude. At the time of the accident the sun's azimuth was approximately 20 degrees west of the alignment of that particular reach of the river. The sun was elevated some 16-17 degrees above the horizon.

Evidence from persons in the aviation community who knew the pilot indicated that he had a love of low flying. The pilot was not approved by CASA (Civil Aviation Safety Authority) to conduct low flying operations.

The weather in the local area was fine with a clear sky and light winds.

Pathology tests revealed the pilot had a blood alcohol concentration of 0.098 g/100ml. Specialist medical opinion indicated that this concentration was most likely the result of alcohol consumption.

Significant factors

The following factors were considered relevant to the development of the accident:

1. The pilot was flying the helicopter at low altitude.

2. The pilot was probably affected by alcohol.

3. The pilot apparently did not see the powerline in time to take adequate avoiding action.

Following a winch launch, the pilot soared the glider for some five minutes. On return to the circuit the glider was flown towards left base and was noted to be low for a normal circuit. Reports indicate that the glider may have then commenced a turn before entering a spin to the left. After two rotations of the spin the glider impacted the ground short of the threshold. No attempt at recovery from the spin was detected by witnesses.

The prevailing weather conditions were a light wind with 3 OKTAS of cumulus cloud above 6,000ft.

Members of the pilot's gliding club stated that the circuit entry flown was uncharacteristic of the pilot.

The Postmortem Examination did not reveal any identifiable cause for incapacity.

The reasons for the loss of control have not been determined.