Loss of control

Circumstances:

The purpose of the flight was to carry out training in simulated forced landings. The aircraft was flown by the student to an airfield, and the instructor demonstrated a forced landing onto the airfield. During the landing roll the propeller is reported to have contacted the ground and thrown mud and water onto the aircraft windscreen. The aircraft was not inspected but was taxied back to the threshold and the instructor commenced a short field take-off. Acceleration to the mid-point of the strip was normal; however, from there on the ground was softer and acceleration reduced. The aircraft became airborne but touched down in the adjoining paddock before running through a fence. During the take-off run, the student, who was watching the airspeed indicator closely, noticed that the instructor attempted to fly the aircraft off the ground at 50 knots, the take-off safety speed being 59 knots. Wheel marks on the strip indicated that the aircraft became airborne 23 metres after the strip end. It settled back onto the ground 130 metres later and ran through the fence.

Significant Factors:

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

1. The strip was unsuitable for the operation.

2. The condition of the strip was not checked prior to the commencement of the takeoff.

3. The pilot did not abandon the takeoff.

4. The pilot mishandled the aircraft controls during the take-off.

Circumstances:

The pilot was undertaking a 300 kilometre triangle cross-country task. A witness reported seeing the aircraft circling at about 400 feet above ground level (agl) before starting to fly a straight path. The aircraft was then seen to begin circling again at a much lower altitude after which it straightened up and flew in the direction of the home airfield. The glider was then observed to nose over and strike the ground without any apparent attempt at recovery. An inspection of the aircraft on site by a club official showed that the airbrakes were fully extended and the flaps were at plus ten degrees when the aircraft impacted. The pilot reportedly could not recall circling at a low altitude, but he believes that he was attempting to land prior to the accident. A probable explanation of the accident is that the pilot allowed the aircraft to stall at a height insufficient for recovery.

A witness, who lives alongside the airstrip, observed the aircraft flying in a north-south direction, about 300 feet above ground level and about 300 metres to the east of his position. The witness took particular notice of the actions of the aircraft and watched as it porpoised three times before diving steeply into the ground. Inspection of the wreckage revealed no defect which may have contributed to the accident. Weather at the time was fine, wind was light and variable, and the aircraft was being flown over flat pastureland. Investigation revealed that the pilot suffered from epilepsy, had heart disease, and that this was his first flight for over one year.

Circumstances:

The pilot had held a Private Pilot Licence for several years, for conventional aircraft only. He bought the gyroplane as a kit and assembled it late in 1988. His brother later bought a similar kit, and this was mostly assembled by the pilot. In the period 31 January-2 February the pilot received 3.5 hours of dual instruction in a two-seat version of the type. The flights consisted of take-offs and flights along the strip. No circuits were carried out. The instructor assessed that the pilot was tending to overcontrol the aircraft and recommended additional training. There was no evidence to indicate that the pilot carried out any further flying. On the day of the accident the pilot carried out a series of taxy runs and short hops along the strip. Following these he flew about six separate circuits, climbing to about 100 - 120 feet, landing and taxiing back to the start point on each occasion. The pilot's brother's machine had never been flown and the pilot suggested that he fly it for him. Two take off runs with brief lift off and landings were made. The pilot then flew several circuits and landings. Late on downwind on the final circuit the aircraft started to porpoise, with increasing amplitude. On about the fourth of these the nose went down, and the aircraft subsequently struck the ground in an inverted attitude. Inspection of the wreckage did not reveal any signs of pre-existing defects. For operation of these machines, it is necessary to ensure that they are flown under a positive gravitational loading. If this is not done the aircraft quickly becomes uncontrollable and may turn upside down. The porpoising manoeuvres seen just before the accident are known to lead to a negative gravitational loading situation if not quickly corrected. Advice provided to the investigation was that the appropriate control action was to reduce engine power to idle and hold the control stick central. In his limited training the pilot had not progressed to the stage of having the recovery technique demonstrated to him. It is possible that with his low experience level he may not have appreciated the dangers of the porpoising situation. While the machine in the accident and the one owned by the pilot were similar, there were some differences. The pilot's own machine was fitted with fairings, a windshield and a horizontal stabiliser. Persons experienced in the operation of gyroplanes consider that with a horizontal stabiliser the machines are more stable and less susceptible to porpoising and negative gravity situations.

Significant Factors:

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

1. Pilot did not obtain sufficient training on gyroplane operations.

2. Aircraft had different design and therefore, different flight characteristics to model previously flown.

3. Probable onset of porpoising, precise reasons undetermined.

4. Pilot unable to regain control possibly due to lack of knowledge and/or experience.

During a Police search for an offender in scrub country, the helicopter was required to hover at about 100 feet over level ground in light wind conditions. After about 12 minutes in the hover with the co-pilot at the controls, it became necessary to re-position the aircraft slightly to the right and rear. To maintain adequate observation of the search area the pilot in command took over the controls and elected to back the aircraft into the new position. Whilst backing-up a slight descent developed. Power was increased but without effect. The pilot then applied full power and forward cyclic control in an effort to arrest the sink and fly away, but descent continued until the aircraft struck the ground heavily. The right maingear was broken and the fenestron shroud sustained damage. After the impact the aircraft bounced back into the air and the pilot maintained a low hover while the extent of the damage was assessed. He then flew the aircraft to the base camp and carried out a successful landing on fuel drums, which supported the right side of the aircraft. The initial slow descent during the back-up manoeuvre was probably the result of the pilot having just assumed control of the aircraft, coupled with a diversion of visual attention while moving towards the required position. The reason for the final, rapid descent could not be established. The aircraft manufacturer had no information relating to previous uncontrolled descents under the conditions which existed at the time, and therefore no procedures had been developed to counter the phenomenon.

The operator of the aircraft had contracted to spray 160 hectares of barley with weed killer. On arrival over the property, the pilot flew an inspection orbit and commenced spraying the first paddock towards some tall trees and a powerline. After this first pass the aircraft was pulled up into a procedure turn before diving steeply over the same obstacles, in the reciprocal direction. When the aircraft was clear of the obstructions, the pilot attempted to level the aircraft for the next spray run. However, the aircraft continued along its established flight path until striking the ground in a pronounced nose high attitude. The impact damaged the propeller, spray booms and landing gear. Chemical sprayed over the windscreen depriving the pilot of forward vision, and he was unable to control the subsequent landing run sufficiently to prevent the aircraft from broadsiding. The aircraft was being operated at a weight in excess of the Agricultural Gross Weight and at a relatively slow airspeed. During the pullout from the dive, the load factor ("G" loading) applied to the aircraft caused an aerodynamic stall. The pilot was unable to effect a recovery at such a low altitude.

Circumstances:

Some months prior to the accident the pilot had begun learning to fly ultralight aircraft. Around this time, he also began to have spells where he was able to see and hear people but could not move or talk to them. His instructor recommended that he stop flying and complete medical tests. The pilot later purchased and assembled a gyrocopter. Over a two-month period he learned to fly the craft. On the morning of the accident, he asked a more experienced gyrocopter pilot to fly his machine and check its characteristics. The other pilot found that it was quite satisfactory. Those who had observed the pilot flying previously considered that he had no problems in controlling the aircraft. The gyrocopter was observed on final approach, but it then disappeared for a short time, having flown an orbit to the left. After adopting a final approach for the second time the gyro flew towards the strip at about 50 knots. A witness observed the craft roll to the left from a height of about 30 feet. The gyrocopter impacted the ground in a left bank of about 130 degrees. No evidence of pre-impact failure of the aircraft was found.

Significant Factors:

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

1. The cause of the accident was not positively determined. It is possible that the pilot suffered a temporary incapacitation during the approach.

Recommendations:

1. That the Civil Aviation Authority undertake, or oversee, an education campaign intended to remind sport aviation pilots of the need to consider their standard of health before undertaking flying activities.

When the aircraft arrived in the destination area, another aircraft was also in the circuit. The pilots were in communication with each other, and arranged that VH-CUO would land after the other aircraft. However, the pilot of VH-CUO apparently misjudged the relative speeds of the two aircraft. He initiated a go-around from a position on final approach to runway 15, when there was evidently insufficient separation with the preceding aircraft to allow a normal landing. The aircraft remained at a low height above the ground, and the pilot broadcast a message that he intended to land in the opposite direction, on runway 33. The wind at the time was from the south-east at about 10 knots. Witnesses observed the aircraft as it tracked along the western side of the runway. The turn onto base leg was made at an angle of bank of about 60 degrees, and about three-quarters of the way around the turn, the nose of the aircraft dropped rapidly. The aircraft then dived steeply to the ground, and was destroyed by the impact and subsequent fire. The subsequent investigation did not reveal any defect or malfunction which might have affected the operation of the aircraft. The pilot was conducting an operation known as a "bank run", and there is pressure on pilots performing such runs to adhere to the prescribed schedules. The pilot's decision to perform a low level circuit and land downwind was considered to be related to his desire to arrive at the terminal as close as possible to the scheduled time. While conducting the circuit, the aircraft stalled during a turn at a height which was too low to allow the pilot to recover control before impact with the ground.

During the flight the pilot reported that he would descend to cruise at 500 feet above ground level. Witnesses saw an aircraft at low level on the expected track, and others heard aircraft noise and then the sound of an impact. Weather conditions were overcast with low cloud covering the hills. The wreckage was found at an elevation of about 4300 feet above mean sea level. The aircraft had apparently struck the ground while in a steep nosedown attitude and rotating to the right. A fire had broken out and engulfed the wreckage. Investigation did not reveal any defect or malfunction of the aircraft which might have contributed to the development of the accident. Both engines were operating at high power settings and the gear and flaps were up. The aircraft had been operating under the Instrument Flight Rules when the pilot reported his intention to descend. Conditions at the destination were suitable for visual flight, and the reason the pilot elected to proceed at a low height above the ground was not determined. It was likely that while cruising below the cloud, the pilot was suddenly confronted by localised adverse weather conditions in the vicinity of the accident site. The maintenance of control of the aircraft under these conditions should have presented little problem to the pilot, who was suitably qualified to operate in instrument conditions. In these circumstances, the precise sequence of events leading to the evident loss of control of the aircraft could not be established.

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