Collision with terrain

Circumstances:

Nearing the completion of a survey flight over a mining prospect, the pilot asked the passengers if they would like to see a crop-dusting manoeuvre. As the passengers had no objection, the pilot flew the helicopter through a steep 180 degree climbing turn to the left from a height of about 300 feet. During recovery from the ensuing dive, the aircraft struck the ground heavily and came to rest inverted. The surviving passenger was thrown from the aircraft after the initial impact. There was no evidence of any mechanical defect in the helicopter which may have contributed to the accident.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The pilot attempted a manoeuvre at a height from which he was unable to recover safely.

Circumstances:

The pilot did not submit flight plan details, but departing Dubbo he advised tracking for Goulburn. No further communication was received from the aircraft, although there was evidence to suggest an intention to proceed to Bega with an intermediate landing at Wollongong. Approximately 80 minutes later, witnesses in the Fitzroy Falls area observed an aircraft fitting the description of VH-MCO, flying very low in various directions, at times obscured by cloud which had enveloped much of the area's higher terrain. Witnesses later heard a noise which caused them to believe that the aircraft had crashed. The area at the time was under the influence of a moist south easterly air mass, with cloud and showers along the coast and adjacent ranges extending to the western slopes of the Great Divide. An extensive air and ground search located the aircraft almost 48 hours later, approximately 100 feet below the level of a ridge. The aircraft had struck trees, which removed the right wing and outer left wing, before coming to rest under a large over-hanging rock ledge. The aircraft was reduced to non-survivable dimensions. There was no evidence of any pre-impact defect affecting the aircraft, and the damage sustained was consistent with the aircraft being in controlled flight at impact. No evidence was found to indicate that the pilot was either qualified or experienced in the conduct of flight in Instrument Meteorological Conditions.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The pilot exercised poor judgement by continuing flight into weather conditions in which he was not able to maintain the visual reference necessary to ensure adequate terrain clearance.

The flight was to survey stock and cull buffalo in an area south-west of the station homestead. After the helicopter failed to return by nightfall, the authorities were notified and a search initiated. The wreckage was located three days later. On-site investigation revealed that the main rotor blades had clipped some small upper branches on a 14 metre high tree before contacting the ground 19 metres further on. The helicopter impacted the ground while banked about 35 degrees to the right and in a nose down attitude of about 35 degrees, but with a flight path substantially closer to horizontal. It then rolled to the right and came to rest against a tree. A severe fire destroyed the cabin/fuselage area. A detailed examination of the engine was not possible because of the extent of fire damage. However, no indication of failure of any major component was noted. Damage to the main rotor blades and ground impact marks from the blades indicated that the blades were being driven by the engine at impact. The state of the tail rotor system indicated that it was intact and also under power at impact. The branches struck by the main rotor blades prior to impact were of insufficient size to have affected the blades or their flight characteristics. The attitude of the helicopter at impact was uncharacteristic for a rotary winged aircraft and indicated that it might not have been under control during the final stages of the flight. This could have been caused by a flight control problem or by some form of pilot incapacitation. Post-impact fire damage to the cockpit/fuselage section precluded a complete examination of the flight control system. No assessment could be made as to the likelihood of pilot incapacitation. A broken engine cooling fan drive belt was found between the tree struck by the main rotor and the initial ground impact point. The other belt was located within the wreckage in its correct position. It could not be established whether the belt was broken and thrown from the helicopter during the impact sequence or whether the belt fell from the helicopter prior to impact. In another recent accident involving the same type of helicopter, the blades on the engine cooling fan had failed. One blade had been thrown against the collective pitch control rod, almost completely severing the rod. Had fan blade failure occurred in the subject accident, (the broken drive belt could indicate this), and a collective pitch or cyclic control rod been struck and severed by a blade, loss of control of the helicopter could have resulted.

Circumstances:

The pilot was conducting mustering operations at low level at the time of the accident. Shortly after the aircraft made a low pass to indicate the position of some animals, it was observed descending at a steep angle. The aircraft commenced rolling to the right just prior to ground impact and was destroyed by a post-impact fire. All essential aircraft systems appeared capable of normal operation prior to the accident. There was no evidence that the pilot had suffered any pre-impact illness or sudden incapacitation. Although all of the precise factors leading to this accident could not be determined, the sequence of events is similar to many other accidents investigated by the Bureau, where the loss of control at low level following a low pass has been due to inattention to aircraft operations by the pilot. It was disclosed during the investigation that although the pilot had a valid mustering endorsement, he had not received any training in recovery from stall/spin conditions, typical of a loss of control in a Cessna 150, at low level.

Significant Factors:

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

1. It is probable that the pilot did not pay sufficient attention to the operation of the aircraft during low-level mustering operations.

2. The aircraft probably stalled and entered an incipient spin.

3. The loss of control occurred at too low an altitude for any recovery attempt to be successful.

Recommendations:

This type of loss of control is a factor in many of the low-level accidents investigated by the Bureau. Training and exposure in incipient loss of control situations, particularly in Cessna 150 type aircraft, is not included in all mustering and associated low flying endorsement programs. The Civil Aviation Authority in Western Australia advised all local pilots of the desirability of obtaining this type of training. It is recommended that the Civil Aviation Authority extend this advice to all pilots in Australia who have approval to conduct fixed wing operations at low level.

The pilot was attempting a normal night takeoff in light drizzle, with 7 to 10 knots of crosswind at the time of the accident. As the aircraft lifted off heavy rain started to fall. The aircraft appeared to accelerate normally to 120 knots. As the pilot completed the after takeoff checks he noted that the aircraft was descending at 200 feet per minute instead of climbing, although the nose of the aircraft was 10 degrees above the horizon. The pilot raised the nose still further and reduced the speed to 110 knots, however, this did not stop the aircraft from descending. At 510 feet indicated on the altimeter, the airfield elevation, the pilot levelled the aircraft and prepared for ground impact. The aircraft touched down, gear up, 3 km from the DEPARTURE end of the runway and slid to a stop in flat marshy country. The meteorological station at Forrest reported that during the aircraft's takeoff, the intensity of the rain increased and the surface wind swung around to give a 30 knot tailwind. During test flights prior to and after the accident the pilot-in-command was assessed as having slow cross reference skills and poor attitude control. It is possible that the pilot's performance contributed to the accident.

The pilot was flying the jump aircraft for a parachute club. After having completed the fifth drop for the day, the aircraft was observed to make a high speed pass, at an altitude of about ten feet above the ground, over a group of spectator parachutists. The aircraft then climbed steeply to an estimated altitude of between 200 and 300 feet before carrying out a wingover type manoeuvre. It then descended rapidly and impacted the ground in a slightly nose low, left wing low attitude, before nosing over and coming to rest 56 metres from the point of impact. The pilot was trapped inside the wreckage and the efforts of would be rescuers were thwarted by a fire which rapidly engulfed the aircraft. An examination of the wreckage failed to reveal any pre-existing mechanical fault. It was reported that the pilot had carried out similar manoeuvres on previous occasions, and had been counselled, about these activities, by the senior instructor at the parachute club.

The helicopter was being used in a program of disease eradication in cattle. After operating for about one hour, the pilot flew to a boat anchored in the river and hovered alongside it while signalling to the crew that the aircraft would return in about two hours. As the helicopter left the hover it was climbed to approximately 60 feet in a left turn through 270 degrees. The aircraft was then descended to an unnecessarily low altitude while gaining speed. Shortly afterwards, as the aircraft approached the bank of the river, the pilot realised that the aircraft was not responding to control inputs as he had expected. He applied more collective control in an effort to avoid flying into the water, but the rotor overpitched and the aircraft struck the water at about 40 knots. No defect was found that would have prevented normal operation of the flight controls or engine.

Three helicopters were engaged in the mustering of cattle on the property. One became unserviceable during the afternoon but returned to the muster after rectification. By 1830 hours the herd of 4000 cattle were near the homestead and one of the pilots was instructed to return to the homestead and land. The other two helicopters continued the muster using the landing lights of the aircraft for lighting. Last light in the area was 1842 hours. At about 1910 hours the muster was nearing completion and the pilot of VH-HMX was instructed by the property overseer to move his aircraft away from the herd. Shortly afterwards the pilot of the other aircraft observed a fire, and upon investigation found the wreckage of VH-HMX. The aircraft had struck the ground in a steep nose down attitude while banked at about 90 degrees to the left. The pilot was neither approved nor qualified to conduct night mustering operations. An inspection of the wreckage found that the landing light had failed prior to impact, however, due to the damage to the helicopter no reason for the failure could be established. It is considered likely that while the helicopter was being turned away from the cattle, the landing light failed and with the the resulting loss of visual cues the pilot became disoriented and lost control of the aircraft.

The pilot in command was continuing a mustering endorsement which had been commenced the previous day. After flying for about 85 minutes the pilots stopped for a break of some 30 minutes. About 75 minutes after flying had recommenced a person on the ground heard a thump, and the wreckage of the aircraft was discovered shortly afterwards. It had struck the ground in a steep nose down attitude while spinning or turning to the left, about 270 metres to the south of the 30 strip. Investigation revealed that, at some stage prior to the final impact with the ground, the undersurface of the left wing had contacted the ground, causing left aileron failure followed by a loss of controllability. Medical evidence indicated that the pilot may have suffered a partial or complete loss of consciousness due to a pre-existing heart condition. However, it could not be determined whether this was a factor in the accident.

The aircraft was being used to convey ABC staff from Rockhampton to Kenlogan Station in order to carry out filming of that and neighbouring properties as part of a planned television program. On arrival in the Kenlogan area the pilot was unable to locate the airstrip and after searching for about 30 minutes a diversion was made to Cumberland Downs (which is now known as Fletchers Awl). Witnesses on the ground at Fletchers Awl watched the aircraft as it arrived and made three circuits of the strip. The landing gear was observed to be extended during the third circuit. The witnesses lost sight of the aircraft as it passed behind rising ground. Shortly afterwards smoke was observed, and it was found that the aircraft had struck the ground about 800 metres short of the strip. A fierce fire had broken out and engulfed the wreckage. The geographical position of Kenlogan as depicted on the appropriate Aeronautical Chart was some 9 km east-south-east of the actual position. Whether this was known to the pilot before the flight could not be established. Examination of the wreckage was hampered because of the extensive fire damage. Although the engines were delivering little or no power at the time of impact, no defect or malfunction with the engines or airframe was found which might have contributed to the development of the occurrence. The cause of the accident remains undetermined.