On 7 May 2005, a Fairchild Aircraft Inc. SA227-DC Metro 23 aircraft, registered VH-TFU, with two pilots and 13 passengers, was being operated by Transair on an instrument flight rules regular public transport service from Bamaga to Cairns, with an intermediate stop at Lockhart River, Queensland. At 1143:39 Eastern Standard Time, the aircraft impacted terrain in the Iron Range National Park on the north-western slope of South Pap, a heavily timbered ridge, approximately 11 km north-west of the Lockhart River aerodrome. At the time of the accident, the crew was conducting an area navigation global navigation satellite system (RNAV (GNSS)) non-precision approach to runway 12. The aircraft was destroyed by the impact forces and an intense, fuel-fed, post-impact fire. There were no survivors.

The accident was almost certainly the result of controlled flight into terrain, that is, an airworthy aircraft under the control of the flight crew was flown unintentionally into terrain, probably with no prior awareness by the crew of the aircraft's proximity to terrain. The investigation report identifies a range of contributing and other safety factors relating to the crew of the aircraft, Transair's processes, regulatory oversight of Transair by the Civil Aviation Safety Authority, and RNAV (GNSS) approach design and chart presentation. It also details safety action taken by various agencies to address the identified safety issues, and includes safety recommendations relating to those safety issues that had not been addressed by relevant agencies at the time of publication of this report.

Recommendations

R20070002 | R20070003 | R20070004 | R20070005 | R20070006 | R20070007 | R20070008 | R20070009 | R20070010 | R20070011 | R20060019 | R20060020 | R20060021 | R20060022 | R20060002 | R20060003 | R20060005 | R20060006

Although there was no applicable minimum distance standard specified for visual separation, the controller was unable to maintain continuous visual separation between the 152 and the 717. The decision by the pilot of the 152 to turn directly onto the base leg of the circuit, and not continue on the downwind leg as instructed, contributed to the infringement of separation standards.

This analysis examines the development of the occurrence and highlights the safety issues that became evident as a result of the investigation.

The controller did not provide the pilots of the 152 or the crew of the 717 with traffic information, or a number in the landing sequence as required by the Manual of Air Traffic Services (MATS). The provision of traffic information was not mandatory and the MATS did not provide any guidance to controllers on the circumstances under which the provision of traffic information would be appropriate. While the controller had intended to provide this information to the pilot of the 152, he relied on a pilot report prior to turning base as a prompt, and this report was not received.

Without the timely provision of traffic or sequence information, the situational awareness of the pilots of both aircraft was reduced. They were effectively excluded from participating in the separation process as described in the Aeronautical Information Publication (AIP) and the MATS. Consequently, the pilots of the 152 were not aware of the broader consequences of their actions once they turned their aircraft onto the base leg. They simply did not recognise that a potential conflict between their aircraft and the 717 existed.

While the flight crew of the 717 was not provided with directed information by the controller, they had been monitoring the radio transmissions between the controller and the pilots of other aircraft in the area. That, together with active scanning of the circuit area for traffic using the traffic alert and collision avoidance system and visual observations, assisted in the resolution of the situation.

The MATS provided no guidance as to whether routinely issued sequencing and separation instructions, such as 'continue downwind', required a read-back. While it may be impractical for the controller to obtain a read-back for every circuit instruction, emphasis should be placed on obtaining a read-back of safety critical instructions. Had the controller requested a read-back of the instruction to continue downwind, and provided a reason for the action, the likelihood of any misunderstanding would have been significantly reduced.

The investigation could not establish whether any aspect of the occurrence sequence could be attributed to the effects of fatigue. However, due to the instructor's non-aviation working commitments, the possibility that fatigue contributed to the occurrence could not be discounted.

On 30 April 2005, at about 1033 Eastern Standard Time¹, a Cessna Aircraft Company A152 (152) aircraft, registered VH-PVX, was being operated on circuit flying training at Hobart Airport, Tasmania. On board were a student pilot and an instructor. The pilot had been issued with a clearance by the aerodrome controller (controller) to conduct right circuits from runway 30 and to operate not above 1,000 ft above mean sea level.

At 1037, a Boeing Company 717-200 (717) aircraft registered VH-LAX, en route from Melbourne to Hobart, commenced the final leg of the Hobart runway 30 VOR² instrument approach. The crew had been issued a clearance by the controller to conduct the final approach. The aircraft was being operated under the instrument flight rules. At about the same time, the controller instructed the pilot of the 152 to make a left orbit to enable the controller to visually separate the 152 with both the inbound 717 and another jet aircraft departing from runway 30. At that time the 152 was at the end of the downwind leg of the circuit.

At about 1039, the pilot of the 152 reported that the orbit was complete and the controller instructed the pilot to continue on the downwind leg and to report prior to turning on to the base leg. However, the pilot had not completed a full orbit but had 'rolled out' of the orbit after completing only a 270 degree turn, directly onto the base leg of the circuit. At that time the 717 was on the final approach leg of the circuit, 90 degrees to the left of the flight path of the 152 and converging.

At about 1041, when the pilots of both aircraft became aware of the potential conflict, the minimum horizontal distance between the two aircraft had reduced to between 400 and 500 m. The 717 was about 300 ft below the 152, and the pilots of both aircraft commenced avoiding action.

The Manual of Air Traffic Services (MATS) 4.5.1.1 stated that visual separation shall be achieved by the use of visual procedures, or by assigning visual separation responsibility to a pilot. The MATS did not specify any minimum distance requirement for the application of visual separation. As the controller was unable to continue to visually observe separation between the 152 and the 717, and had not assigned separation responsibility to the pilot of the 152, there was an infringement of separation standards.

The routine aerodrome weather report (METAR) for Hobart issued at 1030, recorded the cloud as few³ at 3,000 ft and broken at 5,000 ft with visibility greater than 10 km. The pilot in command of the 717 and the controller later reported that the cloud was scattered at 4,000 ft while the 152 instructor believed the cloud base to be broken at about 3,000 ft.

The 152 instructor reported that he had a total of about 270 flying hours including 15 to 20 hours as an instructor. He was relatively new to Hobart and worked about 5 to 10 hours a week flying. He also worked casually in another non-aviation position with shifts that finished late at night or in the early morning.

The instructor believed that his inexperience, together with the cockpit workload involved in instructing the student pilot and controlling the aeroplane in moderately difficult crosswind conditions, reduced his situational awareness. He reported that he was not aware of the 717 on final, and believed he would not have had any opportunity to observe the aircraft until it was established on the final approach because of the low cloud in the area.

The controller had extensive experience in the provision of aerodrome control services at Hobart, and reported that the workload at the time of the occurrence was both moderately busy and complex.

The controller reported that he was applying visual separation between the 152 and several other aircraft. The MATS specified that:

The requirement to provide traffic information was changed from 'mandatory (and)' to 'optional (and/or)' by Airservices Australia in April 2003. On 1 September 2005, Airservices Australia amended the MATS to completely remove the previously amended section 4.5.2.3 relating to the provision of aerodrome traffic information, with the concurrence of the Civil Aviation Safety Authority (CASA), to remove ambiguity over separation responsibilities in the aerodrome traffic zone.

On 16 September 2005, the Civil Aviation Safety Regulation Part 172 Manual of Standards was amended, after agreement between CASA and Airservices Australia, to state:

When aircraft are operating visually as aerodrome traffic ATC must issue 1 or more of the following:

(a) clearances designed to maintain separation

(b) sequencing instructions

(c) relevant traffic information

The issue of the provision of traffic information is subject to an Australian Transport Safety Bureau (ATSB) safety recommendation⁴ (see also Safety Actions section of this report).

The Aeronautical Information Publication (AIP) GEN 2.14.3 also specified that:

ATC will provide relevant traffic information to aerodrome traffic to enable pilots, while complying with ATC instructions, to maintain separation from other aircraft.

The controller reported that the initial orbit instruction given to the pilot of the 152 was to allow for the departure of another jet aircraft and his plan was for the 152 to then extend on a downwind leg until it was possible for the 152 to safely follow the 717 on final. He had intended to pass the pilot of the 152 a number in the landing sequence when the pilot reported prior to turning base. However, as this report was not received, the pilot was not provided with either a number in the sequence or traffic information.

AIP GEN 4.4.1 specified that 'pilots must transmit a correct read-back of ATC clearances, instructions and information which are transmitted by voice' and ensure 'sufficient detail is included to indicate compliance'. The MATS 6.1.13 specified that ATC 'shall ensure that a correct read-back in sufficient detail is obtained'.

Both documents indicated that only key elements relating to certain clearance items must be read back, including 'level instructions, direction of turn, heading and speed instructions'.

The pilot of the 152 did not read back the instruction to continue on the downwind leg, nor did the controller request the read-back. There was no specific requirement in either the AIP or the MATS for the read-back to be provided.

The controller later acknowledged that a sequence number and traffic information should have been provided to the pilot of the 152 and that he believed that a read-back of the downwind instruction would have been beneficial.

Airservices Australia had an annual refresher training program for tower controllers that detailed several mandatory and optional training modules. One mandated module relating to separation assurance was not available to the Hobart controllers at the time of the occurrence.

The 717 flight crew was not provided with traffic information by the controller, but reported that they had been monitoring the radio transmissions between the controller and other pilots. Additionally they had observed the 152, initially on the traffic alert and collision avoidance system (TCAS),⁵ then visually, before commencing avoiding action.

1. The 24-hour clock is used in this report to describe the local time of day, Eastern Standard Time (EST), as particular events occurred. Eastern Standard Time was Coordinated Universal Time (UTC) + 10 hours.
2. Very high frequency omnidirectional radio range.
3. Cloud amounts are reported in oktas. An okta is a unit of sky area equal to one-eighth of total sky visible to the celestial horizon. Few = 1 to 2 oktas, scattered = 3 to 4 oktas, broken = 5 to 7 oktas and overcast = 8 oktas.
4. ATSB occurrence investigation report 200205540 and associated safety recommendation R20040063 available at www.atsb.gov.au.
5. TCAS is an independent onboard collision avoidance system. It is designed as a backup to the ATC system and the 'see and avoid' concept.

On 30 April 2005, the pilot of a Cessna Aircraft Company A152 (C152) aircraft was conducting circuit training at Hobart. The C152 was on the downwind leg of the circuit when the crew of a Boeing Company B717-200 (B717) aircraft commenced the final leg of an instrument approach to the same runway.

The Hobart aerodrome controller was applying visual separation standards and had instructed the pilot of the C152 to make an orbit, and then continue downwind, to separate the C152 from other aircraft. The C152 pilot did not complete a full orbit, but turned onto the base leg of the circuit when the B717 was on final approach. The minimum distance between the converging aircraft reduced to between 400 and 500 m horizontally and 300 ft vertically and required the pilots of both aircraft to commence avoiding action. There was an infringement of separation standards.

The pilot of the C152 did not read back the instruction to continue on the downwind leg to the controller, nor did the controller request this read-back. There was no specific requirement in published documents for the read-back to be provided.

The controller did not provide the pilot of the C152 or the B717 with traffic information, or a number in the landing sequence as required by published documents. This led to a reduction in the situational awareness of the pilots of both aircraft and excluded them from participating effectively in the separation process.

Airservices Australia has advised that they are addressing the issue of obtaining read-backs, when necessary, through controller education and have developed a roving check and standardisation programme for regional towers. As part of that programme, check and standardisation officers place emphasis on the use of correct phraseology and read-back.

The ATSB issued a safety recommendation to Airservices Australia to enhance pilot situational awareness.

On 30 April 2005, the pilot of a Beech Aircraft Corporation V35A Bonanza aircraft, registered VH-FWE, was conducting a private flight from Lilydale, Vic. to Temora, NSW. The pilot reported that while cruising at 7,500 ft, there was a loss of aileron control. Initially the aircraft tended to drift to the right, which he corrected by rolling the aircraft to the left. He then felt something break and the right wing dropped. He turned the aileron control yoke to the left, until it was almost upside down, but the aircraft continued rolling to the right and entered a progressively steeper descent. The pilot broadcast a PAN¹advising air traffic control that he had an aileron control problem and that he would attempt to land the aircraft on a local glider field. He reported that he arrested the roll by extending the landing gear, adjusting engine power and applying full left rudder. The pilot subsequently landed the aircraft without the use of wing flaps.

Aircraft

The aircraft was manufactured in 1969 and had recorded 6,154.8 hours in service at the time of the incident. It was maintained in accordance with the applicable maintenance requirements and had a valid Maintenance Release. It had flown approximately 22.9 hours since the last periodic inspection completed in March 2005.

Aileron control examination

When examined, the aircraft's left aileron was found deflected to the fully down position and the right aileron fully up. To return the ailerons to their neutral position, a force was required to overcome the tension of the rudder interconnect bungee spring. Once the force was removed, both ailerons returned to the fully deflected positions. The examination of the aileron control cables revealed that the right aileron 'up' cable terminal, located in the rear spar carry through structure, had failed.

The aircraft manufacturer advised that since the aileron control cables are connected to the rudder interconnect bungee spring, the separation of the right aileron up cable would result in that spring forcing the left aileron down and the right aileron up (Figure 1).

Figure 1: Aileron control system

Terminal examination

The failed control cable terminal was sent to the Australian Transport Safety Bureau (ATSB) for examination. The terminal shaft that is screwed into the turnbuckle had fractured close to the locking wire attachment point (Figure 2). The examination revealed that the fracture was initiated by stress corrosion cracking² that had propagated under the surface of the shaft and weakened it to the point of failure.

Figure 2: Failed control cable terminal

The cable terminal was a standard swaged fitting designated AN669. Chemical analysis of the material showed that its composition closely matched that of SAE-AISI 303 stainless steel. A recent US National Transportation Safety Board (NTSB) Safety Recommendation³ identified SAE-AISI 303 stainless steel as being susceptible to stress corrosion cracking when used in a corrosive environment. The Safety Recommendation mentioned that cracking propagates as a function of the time a component is exposed to the corrosive environment rather than its actual time in service and that 'about 18 to 20 years is required for terminals exposed to the most damaging environment to reach their fracture point'.

Terminal inspection

During routine aircraft maintenance inspection of control system cables, corrosion pits on the surface of the cable terminal shaft may be the only visual indication of a potential problem. With the shaft area being typically wrapped with safety wire, the shaft can be difficult to inspect.

In August 2001, The Civil Aviation Safety Authority (CASA) issued Airworthiness Bulletin 27-1 Issue 1, Control Cable Terminal Inspection that was also published on the CASA web site www.casa.gov.au. The Airworthiness Bulletin provided information regarding the susceptibility of control cable terminals made of SAE-AISI 303 stainless steel to failure due to stress corrosion and highlighted the 'importance of meticulous inspection of the terminals'. It recommended that aircraft older than 15 years, and using terminals constructed of SAE-AISI 303 stainless steel, should have their control cable terminals visually inspected on an annual basis.

A review of the aircraft's logbooks found no evidence of the aileron controls having been subjected to any specific inspections to detect corrosion, including the removal of lock wire, within the previous 15 years. Routine maintenance inspections had been conducted during that period.

Both the ATSB and CASA databases contained four reports of similar control cable terminal failures in the period between 1995 and 2004. The NTSB Safety Recommendation mentioned 10 instances of aircraft that were found having fractured or cracked control cable terminals.

1. PAN is a radio code indicating uncertainty or alert.
2. A cracking process that requires the simultaneous action of a corrosive environment, such as a chlorine-rich atmosphere in moist coastal areas, and sustained tensile stress.
3. US National Transportation Safety Board Safety Recommendation A-01-6 through -8 of April 16, 2001.

The Australian Transport Safety Bureau did not conduct an on-site investigation of this occurrence.

A Beech V35A Bonanza sustained a loss of aileron control while cruising at 7,500 ft. The pilot reported turning the aileron control yoke to the left, but the aircraft continued rolling to the right and entered into a progressively steeper descent. He arrested the roll by extending the landing gear, adjusting engine power and applying full rudder.

At 0803 Western Standard Time on 24 April 2005, an Airbus Industrie A340-212 (Airbus) aircraft, registered ZS-SLA, with a crew of 11 and 219 passengers, landed short of the displaced threshold on runway 21 at Perth Airport, Western Australia. The aircraft was on a scheduled flight from Johannesburg, South Africa. The pilot in command was the handling pilot for the approach and landing at Perth.

ANALYSIS

The final minutes of the recorded Air Traffic Services radar data indicated that the pilot performed a series of turns in a constant descent that was consistent with a forced landing. Given the pilot's history of performing many practice forced landings, it is likely that immediately prior to the accident, the pilot was conducting a practice forced landing.

When radar contact was lost, the aircraft was already below the minimum altitude for a practiced forced landing and there was no indication that the pilot had decreased the rate of descent. That was confirmed by witnesses that indicated that the aircraft was well below 500 ft above ground level.

Based on the pilot's training records and interviews with flight instructors, it is probable that the pilot was fixated on the chosen landing area and descended below the minimum height for a go-around. During the latter stages of the approach recorded by the radar, the pilot performed a tight 360º turn. That may have been intentional to allow the aircraft to lose height and still be positioned for the selected landing area. During the turn, the aircraft lost approximately 25 kts, which reduced the margin above the aircraft's stall speed.

A person near the accident site reported seeing the aircraft at a very low altitude and flying quietly before hearing power applied. However, the atmospheric conditions around the time of the accident were conducive to the formation of serious carburettor ice at descent power and the engine may not have been capable of producing full power when it was applied. Because the person's attention returned to their duties, it was not known if the application of power that they reported was sustained for any length of time. The evidence in the wreckage indicated that there was little or no power applied at impact. The pilot may have removed power as part of the stall recovery procedure. The use of carburettor heat could not be determined and the formation of carburettor ice was a possibility.

The attitude at which the aircraft impacted the ground and the damage to the tail section indicated that the aircraft had stalled before it impacted the ground. The combination of the loss of airspeed during the turn and the pilot's documented difficulty with stall recognition and response, may have led to an inadvertent stall, either during the go-around or in the subsequent climb out. The height at which the aircraft stalled was not sufficient to permit a recovery. It was not possible to determine if carburettor icing had reduced the power available for the go-around and aggravated the situation.

Fatigue

Based on the pilot's activities and sleep patterns prior to the occurrence, it was apparent that the pilot probably obtained only 5 to 6 hours of interrupted sleep on the night before the accident. Even though this was consistent with his normal sleeping patterns, in all likelihood, the pilot may have started the day with a degree of fatigue as a result of insufficient quantity and quality of sleep the previous night. The pilot may have also been experiencing the effects of chronic fatigue given his recurring pattern of interrupted and relatively low quantity of sleep. Consequently, fatigue may have reduced the pilot's ability to fly the aircraft accurately and to develop and maintain awareness of, and make timely decisions in response to, a degraded aircraft state, such as a stall.

Pilot's training history

The pilot had required a significant amount of flying training to meet the General Flying Progress Test standard. The pilot's training was regular, but spread over a considerable period of time. The training records indicated that the pilot had difficulty in acquiring, maintaining and consolidating the skills required to safely operate a light aircraft. Many lessons were repeated to bring the pilot up to the required competency standard. Of particular note is that the pilot consistently demonstrated poor airspeed control during practice forced landings, indecision, a poor awareness of an impending stall, a lack of response to the stall warning horn, and incorrect stall recovery technique. These factors are consistent with the circumstances surrounding the accident.

FACTUAL INFORMATION¹

History of the flight

At about 0945 Eastern Standard Time² on Saturday 23 April 2005, a Cessna Aircraft Company A150L Aerobat aircraft, registered VH-UPS, departed Coldstream Airfield, Vic. for a private flight in the Coldstream General Flying Training Area, with the pilot as the only occupant (Figure 1).

The aircraft was first tracked by the Air Traffic Services (ATS) radar at 0949 heading in a northerly direction consistent with a departure from Coldstream runway 35. Over the next 6 to 7 minutes, the aircraft made a series of right turns that brought the aircraft into an area to the southeast of Steel Hill. The radar track shows the aircraft performing some aerial manoeuvres in this area before heading north-northeast towards Healesville for several minutes, then turning left for another series of aerial manoeuvres.

The final minutes of recorded radar data (Figure 2) show that the aircraft performed a descending orbit into the Yarra Valley before losing radar contact. The aircraft did not reappear on radar. At about that time, a passenger in a vehicle travelling along the Healesville - Koo Wee Rup Road observed the aircraft flying at low level. Shortly after, the aircraft was seen in a steep dive before it disappeared behind an embankment. The occupants of the vehicle located the wreckage of the aircraft in an open field about 1 km west of the Healesville - Koo Wee Rup Road. The aircraft was destroyed by impact forces and the pilot was fatally injured. There was no fire.

Figure1 : Accident location

Figure 2 : Recorded radar track

Recorded radar data showed that the aircraft maintained a fairly constant rate of descent of about 660 ft/min from an altitude of about 2,400 ft Above Mean Sea Level (AMSL), down to about 700 ft AMSL. That placed the aircraft at about 430 ft above ground level (AGL) when radar contact was lost. There was no indication in the radar data that the aircraft had ceased its descent when contact was lost. The accident site was located about 0.7 NM to the north of the last radar return.

At about 1,000 feet AMSL and heading in a north-easterly direction, the aircraft performed a tight 360º turn³ whilst maintaining the descent. During this turn, the radar recorded a decrease in speed of about 25 kts.

An employee working on the property where the accident occurred observed the aircraft pass at a very low level (estimated between 100 and 200 ft AGL) and flying quietly. The aircraft passed within several hundred metres of the employee and was headed in a northerly direction. The employee reported hearing the engine sound increase before returning their attention to their duties. Having worked on the property for some years, and observed many aircraft training in the area, the employee did not notice anything unusual about the aircraft, other than it being very low. Although located only 900 m from the accident site, the employee did not observe the final moments of the flight or the collision with the ground.

Wreckage information

Ground marks and crushing of the left-wing tip indicated that the aircraft had impacted the ground in a left wing-low and approximately 30º nose-down attitude. The direction of flight was approximately 320º (magnetic). The wing flaps were found in the fully retracted position.

The aircraft came to rest about 10 m from the impact point (Figure 3). The fuselage lay on its roof with the left wing wrapped over the cabin and the right wing in a near vertical position. The rear fuselage was bent downward and to the left. The tailplane had separated from the fuselage and the fin, which was lying on the right tailplane, had broken away from its mounting brackets. There were no indications of any pre-existing defects in the aircraft structure.

Figure 3 : Aircraft wreckage

Examination of the propeller, throttle lever position and engine instruments indicated that the engine was operating at low RPM and developing little or no significant engine power at impact. Examination of the engine found no evidence of a mechanical or system failure that would have prevented the production of power prior to impact. Due to the impact damage, the status of the carburettor heat control at impact could not be reliably determined.

Examination of the stall warning system, airspeed indicator and altimeter indicated that they were capable of normal operation during the flight prior to impact.
 

Personnel information

The pilot's flying experience was estimated as:

The pilot commenced part-time flying training on 23 May 2003 and was issued a Student Pilot Licence on 15 November 2003. The pilot's first solo flight on 23 November 2003 was made after receiving 43.7 hours of dual training. A pre-licence check flight was conducted by a senior instructor on 6 January 2004 when the pilot had 77.3 hours of experience. However, it was not until 24 July 2004 that the pilot achieved the General Flying Progress Test (GFPT) after a further 51 hours of flying training. At that time, the pilot had accumulated a total flying time of 128.4 hours, of which 104.9 hours were dual instruction. All of the pilot's flying training was undertaken at the same organisation.

The flying training organisation's pre-GFPT syllabus indicated that the minimum flying training required to the end of the GFPT phase was 23 hours dual and 6 hours solo, a total of 29 hours. The regulatory minimum total flight time required before attempting the GFPT was 20 hours of flight time.

After completing the GFPT, the pilot commenced cross-country navigation training as part of the Private Pilot (Aeroplane) Licence training syllabus. He had also completed 9.7 hours of aerobatic flight training but had not received an aerobatics endorsement. Entries in the pilot's logbook suggested that the pilot had previously engaged in solo aerobatics with a passenger on board the aircraft.

The pilot held a current Class 2 medical certificate that was endorsed with the restriction 'Renew by CASA only'. The results of the post-mortem examination and toxicology screening found no evidence of any physiological factor that may have impaired the pilot's performance during the accident flight.

In the days leading up to the accident flight, the pilot averaged 5 to 6 hours of sleep per night. These sleep periods were interrupted by waking periods late at night and was reported as the pilot's typical sleep pattern.

A review of the pilot's training records indicated that many lessons were repeated before the minimum competency standards were met. The pilot had recurring difficulties in airspeed management, steep and tight turns, identification of impending stall, response to the stall warning horn, recovery from the stall and go-around decision and technique. The pilot's instructors noted that constant reminders to monitor airspeed and altitude and to perform the appropriate recovery technique were required. The training records included several entries relating to inattention, tunnel vision and trouble attending to all parameters. Annotations of these difficulties were associated with many aspects of the pilot's training, but were particularly apparent for practiced forced landings.

The pilot had recorded a large number of practice forced landings during training, the majority of which were with an instructor.

Practice forced landing

The practice forced landing manoeuvre, as used in the flying training organisation's syllabus, typically involved simulating an engine failure by closing the throttle and gliding the aircraft toward a selected landing area.

The main objective of the manoeuvre was to develop judgement and skill in positioning the aircraft for a gliding approach to the selected field. When the manoeuvre is practiced on to an airfield, a landing is made off the approach. However, when the manoeuvre is practiced in the training area, the student is required to demonstrate a go-around from a safe height, usually not below 500 ft AGL. The go-around manoeuvre requires the pilot to apply full power and select the carburettor heat off, raise the flaps (if used) and establish the normal climb. If, for any reason, engine power is not available, the aircraft is ideally positioned for an emergency landing into the selected field.

To prevent the formation of carburettor ice during the practice forced landing, full carburettor heat is applied. A short application of engine power is normally made every 1,000 ft of descent to maintain engine temperatures. If carburettor heat is not selected off during the go-around, full power will not be available. When the normal climb attitude is maintained with less than full power, the aircraft will climb at a slower airspeed and rate of climb.

Aircraft information

The Cessna A150L aircraft was a two-place, high-wing, light aircraft designed for general flying training, but was also capable of aerobatic flight. The aircraft was powered by a Teledyne-Continental Motors O-200-A normally-aspirated piston engine through a fixed-pitch two-bladed propeller.

VH-UPS was imported into Australia in 1990 and had been operated and maintained by the same flying club since that time. It was utilised for both initial flying training and aerobatic training.

The flying club maintained the aircraft in accordance with a CASA approved maintenance system. The last periodic maintenance inspection was carried out on 23 March 2005. The aircraft's maintenance release, recovered from the wreckage, did not list any defects, and the documentation indicated that all required maintenance was completed. The maintenance release was endorsed by a licensed pilot certifying that the daily inspection had been satisfactorily completed on the morning of the accident. The accident flight was the first flight of the day for the aircraft.

Prior to importation into Australia, the aircraft had been fitted with a carburettor ice detection system in accordance with a United States Federal Aviation Administration approved kit. The system consisted of an optical sensor in the carburettor, a control box and a warning light mounted on the instrument panel. The operating instructions indicated that the pilot was required to adjust the sensitivity of the system to suit the local conditions prior to operation. The operational status of the system at the time of the accident could not be determined.

The aircraft had sufficient fuel and was within the weight and centre of gravity limitations for the duration of the flight.

Meteorological information

The Bureau of Meteorology automatic weather station for Coldstream recorded the environmental conditions for Saturday 23 April 2005 as:

The skies were overcast with high level cloud, there was a degree of haze; however, the horizon in the valley was clearly distinguishable. People in the area reported that winds were very light.

Carburettor icing

On the day of the accident, the atmospheric conditions were conducive to the formation of serious carburettor icing at descent power. Refer to Appendix A for a Flight Safety Australia magazine ⁵ article on carburettor icing.

1. Only those investigation areas identified by the headings and subheadings were considered to be relevant to the circumstances of the occurrence.
2. Eastern Standard Time was Coordinated Universal Time (UTC) + 10 hours.
3. The large changes in the aircraft position in this region are likely due to limitations in the radar system at low altitude, however the general pattern of a tight turn is indicated by the data points at 1106, 1006, 906 and 806 ft.
4. Total time in service.
5. Flight Safety Australia magazine is a publication of the Australian Civil Aviation Safety Authority.

At about 0945 Eastern Standard Time on Saturday 23 April 2005, a Cessna Aircraft Company A150L Aerobat aircraft, registered VH-UPS, departed Coldstream Airfield, Vic, for a private flight in the Coldstream General Flying Training Area, with the pilot as the only occupant.

The aircraft was tracked by the Air Traffic Services radar after its departure from Coldstream Airfield. The radar track showed that the aircraft performed some aerial manoeuvres to the east of the airfield before a descending orbit into the Yarra Valley when radar contact was lost. At about that time a passenger in a vehicle travelling along the Healesville - Koo Wee Rup Road observed the aircraft flying at low level. Shortly after, the aircraft was seen in a steep dive before they lost sight of it. The occupants of the vehicle located the wreckage of the aircraft in an open field about 1 km west of the Healesville - Koo Wee Rup Road. The aircraft was destroyed by impact forces and the pilot was fatally injured.

The aircraft had impacted the ground in a left wing-low and nose-down attitude. The fuselage lay on its roof with the left wing wrapped over the cabin and the right wing in a near vertical position. The rear fuselage was bent downward and to the left. The tailplane had separated from the fuselage and the fin had broken away from its mounting brackets. There were no indications of a pre-existing defect in the structure.

The investigation found that it was likely that the pilot was performing a practice forced landing and had descended below the safe altitude when the accident occurred. The airspeed was reduced to a point that the aircraft stalled and the altitude was not sufficient to affect a recovery before impact with the ground. It is possible that carburettor ice was present during the descent.

Related link: 

In this occurrence, the controller did not perceive the potential conflict between the aircraft, despite previous refresher training that should have assisted in the task.

Although the presence of the supervisor in the operations room created an opportunity to discuss an operational issue, it was not a priority. The controller should have discussed the issue at some other time when he was not responsible for an operational position. The supervisor was also in a position to defer the discussion with the controller, until a more suitable time or location, which would have reduced the likelihood of compromising operations.

While distraction could not be discounted as a contributing factor, the circumstances of the occurrence are consistent with the findings of the Airservices Australia June 2003 review, particularly with respect to low levels of situational awareness by controllers. Over time, the benefits of the implementation of the review recommendations in helping to develop controller awareness of potential performance limitations should become apparent.