Loss of control

The pilot decided to carry out a low fly past along the strip to check the effect of the prevailing strong wind. After having flown along about a third of the strip he landed the aircraft. During the landing roll the wind lifted the left wing and the aircraft began to move off to the right of the strip. The right wheel struck a low dirt mound and was twisted rearward. The aircraft then ran through a fence before coming to rest. The particular strip is an agricultural ALA, with a length of 490 metres and restricted to one-way operations. The pilot was familiar with the strip, having landed there on numerous occasions. The first part of the strip was protected from the wind, and on encountering virtually calm conditions, the pilot had made a spur of the moment decision to land. Shortly after touchdown the aircraft had left the protected area and was subject to a strong and gusty wind.

The pilot had been undergoing a course in aerobatic flying. After completing 11.5 hours of dual aerobatic instruction, she had been authorised to carry out her first period of solo aerobatic manoeuvres. She was briefed to carry out two spins, followed by other basic manoeuvres, consisting of loops, stall turns, rolls and wing-overs. The aircraft was to operate in the designated training areas. About 8 minutes after the pilot reported entering one of the training areas, the aircraft was observed to be at a relatively low height, spiralling in a clockwise direction. Shortly afterwards it struck a group of large trees and dived to the ground. The damage sustained was consistent with a relatively high speed impact. No fault was subsequently found with the aircraft or its systems which might have contributed to the apparent loss of control. It is not known which manoeuvre the pilot was attempting at the time, but assuming that the briefed sequence was being followed, it is likely that the loss of control occurred during the spinning sequence. The factors leading to the development of the accident have not been determined.

The instructor was landing the aircraft in a crosswind from the right. As the speed reduced, during the landing roll, the aircraft began to veer to the right. The instructor applied full left rudder and brake in an attempt to maintain directional control, but the aircraft continued to veer off the strip. Being concerned that the aircraft would strike a fence and overturn, the instructor applied full power in an attempt to clear the fence and land in an adjoining paddock. The aircraft cleared the fence but subsequently stalled and was blown back against the fence.

The pilot was conducting a short cross country flight. As he approached the end of the final leg he realised that there was insufficient height available for the aircraft to make a safe landing at the destination aerodrome. A decision was made to attempt an out-landing as the aircraft passed through 1200 feet on the descent. At that height the choice of fields was restricted and the one that was chosen for the landing was unsuitable. The landing area was covered with long grass and sloped downwards and from right to left. A shallow gully also crossed the area. During the final stages of the approach the right wing touched the ground and long grass causing the aircraft to yaw violently and enter a ground loop. The aircraft finally touched down whilst it was travelling sideways and it came to rest after travelling backwards along the paddock. The pilot was not authorised to conduct cross country flights in the particular aircraft type as he had not completed the required number of flight hours and landings. This accident was not the subject of an on scene investigation.

Circumstances:

On the day of the accident, the pilot took three of her work colleagues on a tour of the mine pits to the North of the camp. When the aircraft returned to the mine's airstrip, the pilot made a low pass over the camp with the canopy fully opened to drop water bombs, before commencing a climbing left turn to rejoin the circuit for a landing. Whilst the aircraft was climbing, the aircraft stalled. The pilot could not regain control before the aircraft collided with the trees. The pilot had been previously instructed not to make low passes over the campsite. The aircraft flight manual indicates that flight with the canopy partly open, but not fully open, is permissible. The effect of a fully opened canopy on the aerodynamics of the aircraft was not determined. The pilot apparently failed to ensure that she maintained a sufficient margin above the stalling speed during the climb out following the pass. This accident was not the subject of an on-scene investigation.

Significant Factors:

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

1. The pilot ignored previous instructions not to make low passes over the campsite.

2. The pilot operated with the aircraft canopy fully open, which may have affected the performance of the aircraft.

3. The pilot failed to maintain adequate airspeed.

4. There was insufficient height available for the pilot to recover before the aircraft collided with the trees.

The pilot and his support crew arrived at the site in the late afternoon and decided to only carry out taxi trials. This was to allow the pilot to get the feel of the controls of his recently purchased, powered hang-glider before flight testing it the next morning. During the last taxi run, it appears that the aircraft became airborne inadvertently. The aircraft climbed steeply to a height of about 150 to 200 feet. Large pitch changes were noted before the attitude stabilised in near level flight. Almost immediately, a shallow right turn commenced which rapidly deteriorated into a descending spiral. The aircraft struck trees and the ground in a vertical dive. Total flight time was 15 to 20 seconds. The pilot had held a Private Pilot Licence some 18 years previously. An offer of flight training had been made by an experienced powered hang-glider pilot, but this offer has been refused because the pilot wanted to teach himself. The control logic of the powered hang-glider was exactly opposite to that of the conventional aircraft on which the pilot had experience.

At 1810 Eastern Standard Time on 30 August 2004, a Fairchild Industries Inc. SA226-T Merlin III aircraft, registered VH-SSL, departed Bankstown, NSW on a charter flight to Glen Innes, NSW with the pilot and seven passengers on board.

The pilot reported that he manually flew the aircraft in instrument meteorological conditions during the climb to flight level (FL)160. On levelling at the cruise level, he noticed that the aircraft was flying in a slightly right-wing low attitude. The pilot said that he applied left rudder trim to level the wings and engaged the autopilot. About 2 ½ minutes later, the autopilot suddenly disengaged without warning. The aircraft then rolled rapidly to the right and entered a steep spiral descent. A review of air traffic control radar data indicated that about 50 seconds later, the aircraft levelled at 5,200 ft. After the pilot regained control of the aircraft, he reported that he noticed that the right fuel tank gauge reading was 350 kg (437.5 L) greater than the left fuel tank gauge reading, and that the aircraft was ‘very heavy on the right-hand side’. The pilot then climbed the aircraft to FL130 and diverted to Tamworth, NSW without further incident. There were no reported injuries to any of the aircraft’s occupants.

The aircraft’s fuel system included a cross-flow valve that allowed pilots to balance the fuel between the aircraft’s fuel tanks if needed. The Merlin III Aircraft Flight Manual contained the aircraft operating checklists. The BEFORE STARTING ENGINES and DESCENT checklists required that the fuel system cross-flow valve switch be closed. The pilot reported that during the diversion to Tamworth he used the cross-flow valve to reduce the fuel imbalance. A subsequent engineering examination revealed no defects in the aircraft’s fuel tanks, fuel vent systems, the cross-flow system, and the cross-flow valve.

The pilot reported that he conducted the last flight in the aircraft a few days before the occurrence flight. The fuel remaining on board the aircraft after that flight was 500 L, and the right fuel tank contained about 150 L less than the left fuel tank. The pilot believed that he might have used the fuel cross-flow valve during that flight. When the aircraft was refuelled before the occurrence flight, 700 L of fuel was added to the right tank and 550 L to the left tank to give a total fuel load of 1,750 L. The pilot reported that after the refuelling ‘the gauges were pretty well reading the same’.

The pilot of a Cessna 340 departed Bankstown, NSW at 1223 ESuT, for Townsville, Qld via Walgett, St George, Roma, Emerald and Clermont. He reported that he climbed the aircraft to 16,000 ft and adopted a long range power setting of about 49% which equated to a true air speed (TAS) of 168 kts and a fuel burn of 141 lbs per hour.

As the pilot approached the ‘OLDER’ waypoint north of Clermont, he reviewed his fuel situation and, because of a strong tailwind decided to continue on to Cairns. He informed an enroute controller of his decision and requested, for fuel planning purposes, a clearance to allow him to track in the opposite direction on a one-way air route. The controller was unable to approve his request but offered the pilot a direct track to Biboohra, a navigation aid 20 NM west of Cairns. The pilot accepted the amended track with the intention of later requesting a more direct route to Cairns.

About 15 minutes later, the pilot requested a more direct track, but was told to call the approach controller for a possible clearance. He contacted the approach controller and told the controller that he had minimum fuel. The controller asked the pilot if he was declaring an emergency, to which he replied affirmative. The pilot later commented that he did this in the hope of expediting his arrival. He was instructed to descend to 6,500 ft and track direct to Cairns. The controller asked the pilot if he preferred to join the runway 15 circuit via a left downwind or right downwind, to which the pilot requested to join a left downwind. The pilot later commented that the aircraft fuel flow gauges were indicating a total flow of 140 lbs per hour and the fuel quantity gauges for the selected main tanks, although wandering somewhat, were ‘displaying a healthy amount’ considering that he was about 12 NM from his destination. As the pilot approached 6,500 ft, he requested a clearance for further descent, to which the controller instructed the pilot to descend to 4,000 ft.

As the aircraft descended to 4,000 ft, the pilot saw Cairns City, but could not see the runway at Cairns airport. The aircraft's distance measuring equipment (DME) indicated 9 NM to the DME navigation aid at Cairns Airport. The pilot reported that at about this time, he observed one of the fuel flow gauges indicating zero, while at the same time, one or both engines began to surge and run roughly. He immediately informed the controller of the situation. The controller asked the pilot if he was familiar with a local airstrip (Greenhill which is 10 NM to the southeast of Cairns airport), to which the pilot replied that he wasn't. The controller indicated to the pilot that the strip was situated in his two o'clock position at a range of about two miles and to be aware of power lines and the sugar cane. The pilot was unsure of what to look for and was unable to see the strip, but after conducting a number of steep turns, saw a cleared strip in a field. He decided that he had to land. He extended the landing gear, but realised that the aircraft was too high and attempted a 360-degree steep turn onto final to reposition the aircraft. However, the airspeed was rapidly decreasing and there was insufficient height to complete the approach. At 1729 EST, the aircraft impacted the ground short of the strip and slid for about 20 metres. The pilot was seriously injured and the passengers received minor injuries.

The ATSB did not conduct an onsite investigation. Witnesses reported that the aircraft's engines were operating just prior to the crash.

The aircraft’s fuel system included main, auxiliary and locker tanks on each wing. During normal operation each engine used fuel from either the main or auxiliary tanks on the corresponding wing. Access to the locker tank fuel was by pilot-activated transfer of the fuel from the locker tank to the same side main tank. Fuel not required by the engine was returned to the main tank regardless of which tank was selected. It was possible for fuel to vent overboard when the main tank was full and fuel was being drawn from the auxiliary tank and/or transferred from the locker tank. Each main tank contained an auxiliary fuel pump that provided fuel pressure for starting and in the event of an engine driven fuel pump failure. A transfer pump was also fitted to each main tank to continuously transfer fuel from the nose section of the tank to the centre sump area of the tank. A function of the pump was to permit steep descents with a low main tank fuel quantity. Pump operation could only be deactivated by pulling a circuit breaker.

The pilot later commented that he had checked the fuel tanks before departure and could confirm that they were full. The pilot had recently flown the aircraft from the USA to Australia.

The pilot later reported that the fuel flow indicator, that had indicated zero, had been repaired about nine months prior to the accident and although initially erratic had operated flawlessly for the last three months. He went on to say that he now has no recollection of what occurred after he descended below 4,000 ft and cannot recall the engines surging.

A number of flight plans, using reported winds from the Bureau of Meteorology, were prepared by the ATSB to consider a number of possible scenarios. These calculations included a greater fuel burn than planned by the pilot, departing with less than full tanks, incorrect fuel tank usage which could result in fuel being vented overboard or remaining in the auxiliary or locker tanks, or a different TAS and groundspeed because of power settings. The ATSB calculations indicated that the aircraft should have arrived, after a descent and straight-in approach from 16,000 ft, with about 95-100 minutes of fuel on board, if fuel management and flight planning were as reported.

At about 1030 Eastern Standard Time on 18 October 2010, a Cessna 172S aircraft, registered VH-VSK, was operating at low level near Durham Downs Homestead, Queensland. A pilot and one passenger were on board.

The pilot was assisting a ground party locate two horses. The aircraft was seen manoeuvring at low level before radio and visual contact was lost. A search later found that the aircraft had impacted terrain near a dry creek bed. Both occupants received fatal injuries, and the aircraft was seriously damaged.

The aircraft's impact attitude was consistent with a loss of control following aerodynamic stall. The pilot was reported to have told another pilot a few days before the occurrence that the aircraft's stall warning system was inoperative. However, the status of the stall warning system at the time of the occurrence could not be confirmed. The investigation identified some other issues which also could have influenced the safety of the flight.

The aircraft operator introduced a number of changes to its policies and procedures following the occurrence.

On 30 August 2010, the pilot of a Robinson Helicopter Company R44 Clipper II, registered VH-ZVF, was intending to operate a private flight from Jandakot aerodrome to Hillside station Western Australia (WA).

Shortly after lift-off, control was lost and the main rotor blades struck the concrete apron adjacent to the departure helipad. The helicopter rolled and came to rest on its right side. The helicopter sustained serious damage and fragments of main rotor blade entered the hangar. Other fragments of main rotor blade were scattered over a large area of the aerodrome. The pilot sustained minor injuries while the passenger was uninjured.

Subsequently, the pilot reported he might have failed to turn the hydraulics on prior to lift- off. This may have been due to distraction created by a problem with a communications system and the unfamiliar departure sequence. The following ATSB publication provides some useful information on distraction:

• Dangerous Distraction: Aviation Research Investigation Report B2004/0324

For a full copy of that report, please visit the ATSB's website at www.atsb.gov.au