At about 200 feet above ground level on final approach the pilot noticed kangaroos near the threshold. He adjusted the approach to fly over the animals but the aircraft subsequently landed heavily about four metres to the right of the centre of the strip. The aircraft slewed to the right and struck a mound of rubble, which was about 50 centimetres high. The right maingear and nosegear folded and the aircraft slid to a halt 105 metres after the point of touchdown. The pilot had landed at the particular strip, which was at an elevation of 4500 feet, on one other occasion. The strip, which did not meet ALA requirements, sloped upwards at 6 degrees over about one third of its length and was 21 metres wide. Mounds of rubble from grading lined each side of the strip, and it was likely that had these not been present, damage to the aircraft may have been avoided. The reason the aircraft landed heavily was not positively determined, but was probably related to the pilot's lack of experience with operations into sloping strips.

Circumstances:

The pilot proposed to conduct a flight around the Station windmills. His attempt to start the aircraft was unsuccessful owing to the battery condition. He turned the ignition, and master switches OFF and proceeded to hand swing the propeller. As he turned the propeller, the engine fired. The throttle had been left half opened, the park brake was not engaged, and the aircraft was not chocked. The aircraft moved rapidly, and the pilot was unable to gain access to the cockpit. The aircraft passed through a fence and subsequently came to rest in a clump of trees. No defect was discovered to explain how the engine could start with the ignition and master switches selected OFF.

Earlier in the day the pilot had flown VH-MDI from a mining camp at Windy North to Broome. On arrival at Broome, at 0913 hours, the pilot was handed a completed flight plan by his Chief Pilot, and briefed for two flights to Koolan Island. The purpose of these flights was to convey nine or ten passengers from Koolan Island to Derby. The aircraft was subsequently refuelled to full tanks and departed Broome at 0956 hours arriving at Koolan Island at 1103 hours. After loading five passengers and their luggage, the pilot taxied the aircraft for take-off from runway 23. Runway 23 is 810 metres in length and has an overall uphill slope of 1.17 percent. The wind at the time was a direct crosswind of between 10 and 15 knots. The aircraft became airborne approximately 54 metres before the end of the runway. It was observed to descend into a small ravine off the end of the runway, then climb steeply and strike power lines before impacting the ground in a near vertical nose down attitude. Following the impact, the aircraft cartwheeled once and burst into flames. Investigation disclosed that the take-off had been commenced from a point approximately 50 metres in from the threshold of the runway. The all-up-weight at the commencement of the take-off exceeded the maximum permitted for the runway selected by about 320 kilograms, given the prevailing conditions. Examination of the wreckage did not reveal any evidence of mechanical defects which could have contributed to the accident. This was the first time the pilot had flown a Cessna 210 type aircraft into Koolan Island although he had been checked on island operations in a different aircraft type by the Chief Pilot.

The pilot was aware that there was an area of soft ground on the strip. The area was marked by a cone marker, which was about 10 metres in from the edge of the strip. The pilot intended to land some 100 metres beyond the cone, however turbulence and strong sink was encountered during the latter stages of the approach. As the aircraft touched down, the tailplane struck the cone marker, which was made of galvanised iron.

The student was receiving instruction in autorotative techniques. The crew completed several autorotative descents terminating in power recoveries. The instructor then demonstrated an autorotation during initial climb at 50 knots, simulating an engine failure after take off. The helicopter was levelled and throttle and collective applied, but the instructor was unable to arrest the rate of descent and the helicopter landed heavily. Following a bounce, the left skid dug into the ground and the helicopter cartwheeled before coming to rest upright, facing in the reciprocal direction to the landing. The instructor commenced the practice autorotation after take off at too low a height/speed configuration. Despite the use of power, he was unable to reduce the excessive sink rate prior to ground impact.

On arrival at his destination, the aircraft overflew the homestead. This was the pilot's normal practice, to indicate to persons on the ground that transport from the nearby strip was required. The aircraft was then seen apparently following a gully containing a sunflower crop in which the pilot and passenger were partners. Shortly afterwards the sounds of an impact were heard. The aircraft was found to have struck the side of the gully while in a steep nosedown attitude and probably rotating to the right. No pre-impact defect or malfunction of the aircraft was found which might have contributed to the development of the accident. However, about 12 months previously, the pilot had applied tape over the stall warning vane, thus depriving him of aural warning of an impending stall. The wreckage distribution was consistent with that which follows a stall at low level where control of the aircraft is not regained before impact. It was likely that the aircraft stalled while the pilot was manoeuvring above the crop, but the precise reason for the stall and subsequent loss of control was not established.

Shortly after take-off the pilot's door opened. The passenger became very agitated and the pilot elected to carry out a low level circuit and landing. The passenger's condition deteriorated to the extent where the pilot was experiencing difficulty in concentrating on the approach. The aircraft touched down in a paddock 22 metres short of the aerodrome boundary fence, ran through the fence and came to rest near the strip threshold. Atmospheric conditions at the time were conducive to the formation of downdrafts and willy-willies. It was possible that the aircraft was affected by such a disturbance at a time when the pilot was distracted by his passenger's condition.

The pilot had only limited flying experience and had not flown at all for more than 12 months. He had owned the aircraft for about 5 years. On the day preceding the accident, the pilot carried out a number of short hops along the strip in the aircraft, but did not attempt to conduct a circuit. Other pilots who were watching reported that the aircraft porpoised during the hops, although the type was regarded as being stable and easy to fly. On the following morning, the pilot commenced a flight in company with two other aircraft. Shortly after take-off, he turned left and tracked towards the north, while the other pilots flew south. His aircraft was last observed to be flying at about 50 to 100 feet above the ground. The wreckage of the aircraft was discovered about 15 minutes later. The subsequent investigation failed to reveal any defect or malfunction of the aircraft which might have led to the accident. Weather conditions were fine and warm and were not considered to have been a factor. Although it was probable that the pilot had mis-handled the flight controls, the precise reasons for the accident could not be determined.

When preparing for the return leg of a charter flight, the pilot discovered that the engine starter motor would not engage. He elected to hand-start the engine, and briefed the passenger on the operation of the controls. No wheel chocks were employed. When the engine started, the aircraft commenced to move and the passenger's efforts to control the aircraft were ineffective. After travelling about 20 metres the aircraft ran into a ditch and the engine stopped after the propeller struck the ground.

After arriving at the property that morning, the pilot commenced mustering operations. The operations were conducted between 50 feet and 300 feet above ground level throughout the day and all manoeuvres performed appeared normal to ground observers. Later in the afternoon a witness reported that he observed the aircraft perform a steeper than normal climb before diving towards the ground. The aircraft subsequently impacted the ground in a steep nose down, wings level attitude, bounced, then slid forward for 13 metres before the left wing struck a tree. Examination of the wreckage did not reveal any defect with the aircraft that could have contributed to the accident. It is probable that the pilot was fatigued after a long day and that he inadvertently allowed the aircraft to stall at the top of the climb. Insufficient height was then available to allow a recovery to be effected.