1. The flight plan was poorly constructed and was not used to monitor the progress of the flight.
2. The errors in the flight plan may have provided the pilot with a false impression that he had sufficient fuel for the flight.
3. The pilot did not maintain an adequate sense of time, distance and fuel endurance.
4. The engine failed due to fuel exhaustion.
5. The pilot did not take advantage of suitable areas available for a forced landing.
6. The aircraft stalled at a height from which recovery was not considered possible.

The flight plan used by the pilot for monitoring the flight was written in a manner that was not in accordance with conventional flight planning techniques. This meant that the recording of departure and arrival times, and the monitoring of the flight's progress, might not have been as straightforward as when using the conventional technique. No waypoints other than departure and destination points were entered, except for the significant sightseeing destinations of the Bungle Bungles and the East Alligator River area. The use of intermediate waypoints could have assisted the pilot in establishing arrival times and in monitoring the duration of the flights. A large error in the planned time interval between Kununurra and Tindal was considered to have been a significant factor in this accident and would have contributed to the pilot's overall lack of situational awareness during the accident flight. The overall plan allowed barely adequate time for refuelling at each landing point and made no allowance for time to be spent in sightseeing at significant locations. As a result, the day's activities were artificially shortened at the planning stage and the day's flying would inevitably take longer than originally planned.

Minimal notations of position and time on the flight documentation available suggested that the pilot was using the GPS as his main source of position and time reference. The balance of evidence also suggested that the pilot was not experienced in planning and conducting ad hoc scenic flights such as occurred on that day. It also suggested that the pilot did not monitor the relationship between the aircraft's position, time, and endurance remaining. There was no apparent recognition that the flight plan lacked the route segment between Timber Creek and Tindal.

The errors in the flight plan meant that the flight-planned fuel required for the Kununurra to Tindal flight, was inadequate. Considering that a more accurate time interval for the flight to Tindal would have been 3 hours 20 minutes, fuel should have been of considerable concern. The pilot apparently did not associate the delays in the flight and the additional leg from Timber Creek to Tindal with the amount of fuel available. On arrival in the Tindal circuit, the pilot did not appear to be aware that the fuel supply was almost exhausted, as none of the pilot's radio transmissions indicated any sense of urgency or need to land promptly.

When faced with the emergency, the pilot did not take advantage of available options that could have minimised the consequences. Once the engine power began to fail, it is likely that the pilot was concentrating on the reasons for the power loss and was attempting to restore power rather than considering suitable areas in which to make a forced landing. The pilot had not attempted to configure the aircraft for a forced landing as evidenced by the retracted landing gear and flaps at impact. The aircraft speed taken from the Tindal radar system recording and the witness reports of the aircraft "porpoising" prior to impact, are consistent with the aircraft stalling at approximately 300 ft AGL. With the aircraft in a stalled condition, the pilot had little control over the aircraft.

A Cessna 210 (C210), operating under visual flight rules, was chartered for a one-day aerial sightseeing flight by a group of four interstate visitors. The flight departed from Darwin NT and flew to Kununurra WA where the aircraft was refuelled. It has been established that the aircraft held fuel for approximately 240 minutes of flight when it departed Kununurra. This was consistent with the fuel endurance noted on the flight plan.

From Kununurra, the aircraft flew to the Bungle Bungle Range (Bungle Bungles) WA, where some scenic flying was carried out before continuing to Timber Creek NT for an unscheduled landing due to the unavailability of an air traffic control clearance into Tindal airspace. During this leg of the flight the pilot amended his SARTIME for arrival at Tindal by 1 hour 30 minutes. The aircraft then flew to the Tindal airport at Katherine NT, where a refuelling stop had been planned. The pilot again amended his SARTIME for arrival at Tindal by a further hour. Approaching Tindal, the pilot communicated with other aircraft in the area and manoeuvred to establish a traffic pattern. After further communications, the pilot advised that he was joining downwind for runway 14. Shortly after this, the aircraft was observed to be flying at a very low height with the engine "spluttering". Witnesses saw the aircraft "porpoising" as it descended into trees. The sound of an impact was heard shortly after. The aircraft speed taken from the Tindal radar system recording was consistent with the aircraft being in a stalled condition from approximately 300 ft AGL.

The accident site was located approximately 6.6 km west of Tindal airport. Adjacent to the accident site were a number of areas suitable for a forced landing. Apart from these areas, the terrain was generally flat with occasional rocky outcrops, and was moderately treed. The accident site was contained within the moderately treed area. The five occupants had received fatal injuries.

Pilot information

The pilot held a commercial flight crew licence, a valid class one medical certificate and appropriate endorsements to allow him to operate C210 aircraft. The operator employed the pilot on a casual basis.

At the time of the accident, the pilot had accrued a total of 798 hours flying experience. Of this, 636.8 hours were in command with 481.3 hours on C210 aircraft. In the previous 30 days he had flown 47.2 hours, all of which were conducted as pilot in command on the C210. Evidence indicated that the last time the pilot had demonstrated practice forced landings was in March 1996. Evidence also indicated that the pilot had not previously conducted an extended flight with fare-paying passengers as was planned on the day of the accident.

Wreckage examination

The combination of speed and descent angle of the aircraft resulted in an estimated descent rate at impact of about 3,100 ft/min and an estimated peak impact load of 64G. Such an impact was not considered to be survivable.

The right fuel tank had been ruptured at its inboard end and there was evidence that a small amount of fuel had been released from the ruptured area. The left fuel tank was intact and it contained about one cup of fuel. Traces of fuel were found in some areas of the engine fuel system, most areas being dry. The aircraft was assessed as containing no useable fuel at the time of impact. The engine instruments indicated that the aircraft had flown for approximately 240 minutes since refuelling at Kununurra.

The landing gear and flaps were retracted and there was no evidence that either had been selected in anticipation of configuring the aircraft for a landing.

Flight Planning

On the reverse side of the flight plan form, the pilot had documented the planned flight legs for each route. Each line commenced with the departure point and contained the data for the flight to the destination. This method was not in accordance with the conventional method of flight planning and meant that the thought process required for each line of data was to think FROM the location at the beginning of the line rather than TO the location at the beginning of the line.

The line on the flight plan commencing with "KU" contained data applicable for the flight from Kununurra to the Bungle Bungles, a distance of 100 NM and an estimated elapsed time of 45 minutes. No time had been planned for sightseeing at the Bungle Bungles.The line on the flight plan commencing with "BU", assumed to be the Bungle Bungles, contained data applicable for the flight from the Bungle Bungles to Timber Creek, a distance of 161 NM and an estimated elapsed time of 1 hour 12 minutes. No data had been entered on the flight plan for the leg between Timber Creek and Tindal, a distance of 131 NM, which would have been expected to take approximately 60 minutes. A more accurate planned time interval, calculated by the investigation team, for the flight between Kununurra and Tindall was approximately 3 hours 20 minutes, including an allowance of 20 minutes for flight in accordance with standard operating procedures for sightseeing at the Bungle Bungles. The pilot's flight plan indicated that he had allowed only 1 hour and 57 minutes. No waypoints other than departure and destination points were entered, except for the significant sightseeing destinations of the Bungle Bungles and the East Alligator River area. The anomaly in the flight-planned time between Kununurra and Tindal was consistent with the information contained on the other side of the flight plan form and which was submitted to Airservices Australia for flight notification purposes. Although the actual time of landing at Timber Creek could not be established, evidence suggested that the actual time from Kununurra to Timber Creek was probably about 2 hours 50 minutes. Although two fuel calculation columns were annotated with "KU" and "TN" under the "endurance" line at the bottom of the table, no other entries were made in the columns.

Fuel considerations

Persons interviewed during the investigation said that the pilot considered fuel loading prior to flights and there had been occasions when the aircraft's load was reduced in order to carry an adequate fuel load. However, there was some evidence, other than on the accident flight, that the pilot was not in the habit of maintaining a running log of time, distance and fuel endurance. The operator's chief pilot advised that during the pilot's most recent check, he noted that the pilot used only the GPS for navigation and did not keep a flight log, but that he always seemed to know where he was.

There was no evidence to suggest that the fuel gauges were unreliable. A video recorder recovered from the wreckage contained a recording of the flight taken by one of the passengers and provided a clear view of the instrument panel while the aircraft was on approach to land at Timber Creek. The left fuel gauge indicated that the tank was nearly empty while the right gauge indicated approximately one quarter full. Calculations based on this evidence determined that the aircraft had approximately 15 US gallons or some 57 L on board during the approach to Timber Creek, which equated to approximately 1 hour's flight time.

The operator

The chief pilot was the owner of the organisation and the only full-time employee. Three part-time pilots, including the pilot of the accident flight, were employed on a casual basis. From June 1994, the operator's AOC was upgraded from aerial work to include charter operations.

The company operations manual required the chief pilot to ensure that pilots rostered for charter flights familiarise themselves with the route and conditions expected along the route. The chief pilot reported that he had not seen the pilot's plan, and that he had not discussed the plan or the route in detail with the pilot before he departed on the accident flight.

Navigation

One Global Positioning System (GPS) unit was recovered from the wreckage and another was found in the pilot's bag. The unit in use on the accident flight contained waypoints appropriate to the flights conducted on the day of the accident; however, the route-tracking facility was not selected. Although the unit could be used for fuel endurance calculations, no parameters had been entered into the unit to allow this to occur. The last position retrieved from the unit after the accident was consistent with the accident location.

Information obtained during the investigation suggested that the pilot tended to use the GPS exclusively for navigation, and was not in the habit of recording any fixes on a map or other documentation. This information was consistent with the evidence provided by the pilot's documentation recovered from the aircraft. No entries had been made on the pilot's navigation charts. Only the intended tracks had been drawn on them. Some positions and estimates given by radio would most likely have been obtained by reference to a GPS unit.

The flight plan contained almost no information other than that entered during the flight planning stage. No positions and times were entered. There was no evidence of any attempt to maintain a fuel log by recording fuel quantities at significant points, or recording tank selection times.

1. The pilot did not remain at the controls of the helicopter.
2. The helicopter was parked crosswind.
3. The helicopter landing site did not have a non-slip surface.

When the helicopter weathercocked through 30 degrees, probably as a result of the weight reduction when the passengers and their baggage were removed, the main rotor was no longer biased into wind but produced both a vertical and horizontal lift component. This allowed the helicopter to slide rearwards and pitch up. As the left skid dug into the hatch surface, possibly due to the pilot's weight on the left side, the helicopter commenced a dynamic roll-over and fell off the hatch cover onto the deck.

Had the pilot remained in the cabin, he would have been able to manipulate the controls to prevent movement of the helicopter.

The MV " Karoo ", a large bulk carrier, was at anchor 11 km off Mackay, facing approximately 090 degrees M. The wind was from the south-east at about 25 kts. The helicopter had been chartered to transfer two members of the vessel's crew from shore to the ship. After an uneventful flight, the pilot landed the helicopter on the port side of cargo hatch number seven which measured 20.0 m by 14.45 m and had a smooth painted steel surface. The cargo hatch peaked in the centre and sloped down 0.85 degrees to both the port and starboard sides of the ship. The pilot positioned the helicopter so that the tail rotor protruded over the edge of the hatch on the port side. In this position, the helicopter was under the influence of a crosswind from the left front quarter. The pilot stated that he reduced the engine power to ground idle, friction-locked the cyclic and collective controls, and locked the anti-torque pedals. He then exited the cabin and walked to the right side of the helicopter to supervise the disembarkation of the passengers and to remove their luggage.

After the passengers had stepped from the helicopter, it weather-cocked about 30 degrees to the left and commenced to slide slowly backwards towards the edge of the cargo hatch. The pilot ran back to the left side of the helicopter and attempted to unlock the anti-torque pedals prior to climbing aboard. The front of the helicopter then pitched up with the pilot partly on board, then fell 3 m onto the main deck and landed inverted beside raised piping which ran along the length of the deck. The pilot fell between the hatch and the piping and was saved from flailing rotor blades by two steel posts supporting the pipe system. The engine continued to operate for 30 to 60 seconds after the impact.

In accordance with standard procedures, the vessel's fire-fighting crew was on duty for the arrival of the helicopter. The crew sprayed the wreckage with foam and salt water as a precaution against fire.

Examination at the accident site revealed scratch marks that indicated that the left skid landing gear had dug into the painted hatch surface. The rear portion of the left skid broke in overload as the helicopter pitched up. Examination of the wreckage confirmed that the pilot had locked the controls and that the throttle control was positioned in the ground-idle detent.

Additional information

An Australian Maritime Safety Authority (AMSA) booklet "Ship - Helicopter Transfers, Australian Code of Safe Practice", states that the helicopter landing site (HLS) should have a non-slip surface. On the MV "Karoo", the cargo hatch designated as the HLS was painted, smooth steel plate. It did not have a non-slip surface.

Civil Aviation Orders (CAO) generally required that the pilot remain at the controls during engine operation. However, CAO 95.7.7 allowed an exemption if the pilot considered that passenger safety, or the safety of people in the vicinity, may be compromised, provided that the controls were locked, and the pilot remained in the immediate vicinity. The pilot in this instance regarded the passengers as potentially at risk due to their unfamiliarity with the helicopter operations and their inability to understand English. As an additional safety consideration, he had positioned the tail rotor beyond the edge of the cargo hatch.

The crosswind landing technique required the pilot to counter the total effect of wind on the helicopter by positioning the cyclic control so that the main rotor thrust was biased into wind, towards the 10-o'clock position, to counteract the aerodynamic drag. When the pilot locked the controls, the cyclic control was locked in the position that was selected for landing, maintaining the main rotor bias.

While on descent into Melbourne, the crew of a British Aerospace 146 (BAe 146) freighter reported that they began to smell oil fumes. The descent was being conducted at an engine power setting of between 60% and 70% N2, with all four engines supplying bleed air. Both environment control system (air conditioning) packs were selected ON. The crew, who were the only occupants of the aircraft, consisted of the pilot in command, the co-pilot, and a supernumerary pilot. The pilot in command was the handling pilot for the sector.

The pilot in command advised that, following the onset of the fumes, he had experienced difficulty in concentrating on the operation of the aircraft, and had suffered from a loss of situational awareness. By the time the aircraft had reached an altitude of approximately 2,000 ft, his control inputs had become jerky and he began suffering vertigo. He relinquished control of the aircraft to the co-pilot, who continued with the approach and landing. The supernumerary pilot advised that he had felt nauseous. The pilot in command advised that because no smoke or mist was present within the cockpit, he did not consider it necessary to follow the smoke-removal checklist. He also advised that the crew did not consider the use of crew oxygen masks was necessary in the situation.

After boarding the flight in Sydney, the supernumerary pilot had examined the aircraft maintenance release and noted a deferred defect concerning oil residue at the number two air conditioning pack inlet, resulting from an oil leak from the number four engine. This maintenance release entry was dated 17 June 1997. Maintenance troubleshooting had isolated the problem to a failing oil seal within the number four engine. The aircraft had been cleared for further flight without any operational restrictions being noted, and the defect was listed for rectification at company convenience.

On experiencing the fumes during the descent into Melbourne, the supernumerary pilot recalled that he had noted a defect concerning the number two air conditioning system, and rechecked the maintenance log to determine which bleed air system may have been contributing to the source of contamination.

After shutdown at Melbourne, the crew vacated the aircraft. Following exposure to fresh air for about 30 minutes, the effects of the oil fumes dissipated. As a result, the crew did not consider it necessary to seek medical advice before continuing the scheduled flights. This decision was reinforced by the fact that the co-pilot had not reported being affected by the fumes. The crew further advised that because the technical log already contained an entry regarding the number four engine, and because Maintenance were aware of the problem, another entry regarding the same problem was unnecessary. They elected to continue the remaining scheduled flight sectors with the number four-engine bleed air system turned off, in accordance with the provisions of the master minimum equipment list (MMEL). The remainder of their tour of duty was completed without incident.

Some 6 hours after the incident, and for the next 10 days, the pilot in command suffered from severe headaches characterised by the feeling of a strong pressure on the top of the head. This diminished over time; however, he did report having balance problems while attempting to rise in a darkened room at night, and also reported that he had experienced increased headaches and vertigo while travelling. The supernumerary pilot reported reduced but similar symptoms. The co-pilot did not report having been affected by the fumes.

Following this occurrence, the pilot in command submitted an air safety incident report, and also advised the operator of the circumstances of the occurrence. The operator applied minimum equipment list (MEL) 20-50-1 on 14 July 1997, prohibiting the use of the number two air conditioning pack, thus preventing oil contamination of the air conditioning system by the number four engine. The engine was subsequently replaced on 16 July 1997.

The BAe146 aircraft is a high-wing, four-engine jet transport, which first entered service in 1983. An auxiliary power unit (APU) is mounted in the tail, along with two environment control system packs. High temperature bleed air is supplied by the compressor section of each engine and the APU. The bleed air is then passed through the environment control system packs, where it is conditioned before distribution into the aircraft cabin.

During the course of the investigation, a number of flight and cabin crew members, employed by various Australian operators on BAe146 type aircraft, reported to the Bureau that they and others were experiencing a number of health problems. The crew members reported that they were either off work permanently, on prolonged sick leave, or in receipt of medical certificates that precluded them from undertaking normal crew duties on the aircraft. The crew members reported a variety of differing physical reactions arising from their perceived exposure to fume contamination, the most common being sore eyes, nose and throat; nausea; tiredness; and headache. The more disabling reactions reported include any of the above symptoms plus any of the following: dizziness, balance problems, extreme tiredness, extreme reaction to all oil-based products (including plastics and cosmetics), feelings of intoxication, slurred speech, inability to walk straight, skin rash, itchiness and blotching.

The investigation found that smoke and fume contamination of cabin air is neither a new phenomenon nor a particularly rare event and that over time, it has been experienced in many aircraft types. The Australian experience has found that many complaints have been recorded against the BAe146 type. As a result, Australian domestic operators of the BAe146 have established internal reporting systems whereby reports of odours are submitted by crews on specifically designed forms that are collated and analysed, as a means of establishing the extent of the problem.

In August 1997, the operator published a Notice to Pilots (NOTOP) 37/97 concerning alleged air conditioning contamination on BAe146 and Avro RJ aircraft types. The NOTOP stated that it was not a new phenomenon, and that all aircraft air conditioning systems would induce foreign odours from oil or fuel on occasions during routine operations. Attached to the NOTOP was a schedule to be used by flight crew to determine the source of air conditioning contamination. The schedule required flight crews to operate BAe146 aircraft on a series of sectors with various air supply and air conditioning pack selections to identify the source of contamination.

One operator supplied air-sampling kits on board the aircraft, and medical checks were offered when crew complained of exposure to cabin air contamination. The Bureau of Air Safety Investigation was unable to determine if details of all reported odour occurrences were entered into aircraft maintenance logs. Other reports were made directly to medical personnel, some to employee representatives, and some were made verbally to the Bureau. Some reporters advised that they would not report to their employers because they feared reprisals.

Visual descriptors of the contamination included "smoke", "fumes", "oil mist", and "fog". Smell descriptors included "acrid", "vomit", and "smelly socks". The investigation labelled all described forms of contamination as odours. It was found that the odour reports defined two distinct modes: one that could be associated with oil fumes, and another that could be associated with a stale air environment. Identified causes of foul air supply included engine and APU oil seal leakage, hydraulic oil leaks, electrical component overheating, and problems associated with food heating facilities in galleys.

BAe146 operators approached the manufacturers of the aircraft, engines and APU. As a result, a series of tests and trials were designed to ascertain whether the aircraft met all the relevant certification requirements, and whether modifications were required to alleviate the cabin air quality problems being experienced from time to time.

As a result of testing and research, operators undertook a number of corrective maintenance actions and modifications to BAe 146 aircraft in the Australian fleet in an attempt to mitigate odour occurrences within the cabin. These actions included more frequent air filter cleaning, replacement of APUs with an alternative unit, modifications to APUs to improve ventilation in and around the unit and associated air intakes, assessment of filter life, air duct cleaning, and the replacement of ducts likely to trap oily deposits. The air conditioning packs were also "burnt out" on a daily basis. This procedure was intended to increase pack operating temperatures in an attempt to burn off any remaining oil residues within the air conditioning system, but was discontinued by Australian operators because it apparently caused deterioration of the packs. There was also an increase in the frequency of engine oil seal inspections and replacement.

The Bureau of Air Safety Investigation is particularly concerned about the potential for further BAe146 flight and cabin crew to become incapacitated during flight due to exposure to odours being introduced into the aircraft cabin environment. In this occurrence, two of the three flight crew members on board the aircraft suffered from symptoms that prevented them from properly carrying out their assigned duties. The introduction of fumes and odours into the cabin environment following an engine defect constitutes a possible safety deficiency that should be addressed by the regulatory authority, in accordance with its statutory responsibility to monitor the continued airworthiness of aircraft.

The implications of long-term exposure to cabin air contamination for the health of passengers and crew requires further examination, together with the development and implementation of suitable countermeasures. The competent authority to co-ordinate such activities is the regulatory authority.

Air traffic control

Brisbane Sector 10 was operated by a trainee controller under the supervision of a rated training officer. The trainee had obtained a rating on sector 11 approximately eight months earlier and had been operating that sector prior to commencing training on sector 10. The training officer was not the trainees regular training officer.

The trainee passed the Brasilia's Lockhart River position information to the FIS 7 officer at 1217 and during this coordination process, accepted the responsibility to pass traffic information on the Dash 8 to the crew of the Brasilia. The trainee discussed the passing of this traffic information with the training officer and correctly calculated a time of passing, which would be near to the point of descent for the Brasilia. The trainee felt comfortable with such confliction in controlled airspace and had prepared a plan for such an eventuality. The training officer would have preferred the trainee to ask for the Dash 8 crew to be transferred to the control frequency and perform the separation task in controlled airspace. However, the trainee decided to instruct the crew of the Brasilia to contact FIS 7 early, which would allow the two crews to arrange their own separation.

It was not until 1226, after the Brasilia crew had commenced descent, that the trainee finally communicated this traffic information. This broadcast was only made after a prompt from the training officer. The trainee had not written any prompt on the flight strip and was not required to do so. The callsign of the conflicting traffic was notated on the flight plan strip for the Brasilia after passing the information, which was in conformance with the procedures designated in the Manual of Air Traffic Services (MATS).

This was the first time that the trainee had been required to communicate traffic information in a situation where one aircraft was in controlled airspace and the other outside controlled airspace and did not feel confident about doing so. The trainee had intended to perform the task but became distracted by other work-related matters.

Training

The trainee had not witnessed or trained for such a scenario since leaving the training college over 12 months before.

The Sector 10 training program was incomplete and the simulator exercises that were available did not contain any scenarios dealing with traffic conflict near the base of controlled airspace. Although more simulator training was scheduled, the trainee had only received two sessions due to simulator unavailability.

The procedures for flight strip annotation did not require any notation prior to passing traffic information and the trainee did not make any. However, the training officer's usual method was to make such a notation in order to provide a memory jogger, in case he became distracted prior to completing the task.

As the trainee was nearing the end of the training period, the training officer was prepared to give the trainee as much scope as possible to work unprompted. He had seen the trainee perform tasks satisfactorily to that point and felt confident that the information would be passed as required. He was surprised when the trainee issued descent instructions without passing the traffic information. Consequently, he prompted the trainee to make the necessary transmission.

Flight service

The flight service officer had correctly assessed the conflict between the aircraft when he received the coordination from the Sector 10 controller. The coordination included the phrase "calls you top of descent" which the flight service officer thought was exactly what would happen. He passed traffic information on the Brasilia to the crew of the Dash 8 and planned to pass information to the Brasilia crew when they first called on the FIS 7 frequency. However, the trainee controller volunteered to pass the information for him. He had calculated that the 2,000 ft difference between the cruising level of the Brasilia and the base of controlled airspace would have given him sufficient time to pass this information to the crew before they departed controlled airspace.

The flight service officer had made a judgement in relation to the rate of descent of the aircraft when there was no performance data provided for his reference.

At the time the Brasilia crew first attempted to make radio contact on the FIS 7 frequency, the frequency was congested. This situation resulted in the Brasilia crew being unable to make a broadcast on the FIS 7 frequency between 1227:30 and 1228:16.

Crew of the Dash 8

Having been given traffic information on the Brasilia shortly after departure, the crew of the Dash 8 elected to initially maintain FL190 while contacting sector control for an airways clearance. They expected the Brasilia crew to descend to FL200 outside controlled airspace to facilitate discussion between the crews in order to agree on a suitable method of separation.

On passing FL180, they changed to sector control frequency as planned. As they did so, they received a call from the crew of the Brasilia, on the FIS 7 frequency, asking for their height. They did not communicate with sector control immediately in order to converse with the Brasilia crew. By the time they had established their relative altitudes, the two aircraft had passed.

Documentation

Aeronautical Information Publication (AIP)

A pilot flying under the Instrument Flight Rules (IFR) may use Visual Flight Rules (VFR) procedures if flying in visual meteorological conditions. A regular public transport flight must proceed in accordance with IFR but this does not preclude the change to VFR procedures which allow a pilot to proceed on a "see and avoid" basis.

The AIP requires aircrews to establish communication on the relevant FIS frequency prior to descending from controlled into non-controlled airspace.

Manual of Air Traffic Services (MATS)

Chapter 3 of this document gives basic guidance to flight service officers in relation to passing traffic information and recognition of potential conflicts. It states, in part, that "when in doubt, advise". Although it contains the most likely circumstances for traffic assessment, it does not contain any guidance on aircraft performance.

Aircraft company procedures

Company documentation for the Brasilia operation reflected AIP requirements but allowed individual pilot interpretation. This situation did not necessarily reflect company policy in the area of radio communications when transiting from controlled airspace into non-controlled airspace.

The company operating the Brasilia were in the process of developing appropriate standard operating procedures when this incident occurred.

1. The sector 10 trainee had not received adequate training in the control of conflict situations near the base of controlled airspace.
2. The sector 10 training officer was not familiar with the performance of the trainee and allowed the delay in passing traffic information to become significant.
3. The sector 10 trainee did not pass traffic information on the Dash 8 to the crew of the Brasilia in a timely manner.
4. The pilot in command of the Brasilia did not establish a positive separation procedure with the Dash 8 while on descent from controlled airspace.
5. The crew of the Brasilia did not make the required radio broadcast on FIS 7 frequency prior to leaving controlled airspace.
6. The pilot of the Brasilia decided to proceed visually and use "see and avoid" principles.
7. The company procedures of the Brasilia crew did not specifically cover the radio procedures for flight from controlled airspace into non-controlled airspace.

Air traffic control

The trainee had never communicated traffic information under these circumstances before and was unsure of exactly how to do so. The trainee had also not had to pass any traffic information during the training period on sector 10. This situation may have contributed to the delayed transmission.

The fact that the training officer and trainee had different preferred methods of notating flight strips and dealing with traffic conflictions near the control area boundary, may have caused some misunderstanding between the trainee and the training officer which, in turn, may have led to the delay in the training officer's prompt.

Flight service

Had the trainee controller not volunteered to pass the traffic information, the decision of the flight service officer to wait for the Brasilia crew to make their general broadcast on the FIS 7 frequency before passing traffic information on the Dash 8, may have resulted in the Brasilia passing through the level of the Dash 8 before the crew received the traffic information.

The predication that the crew of the Brasilia would contact him at "top of descent" did not allow for any of the delays that occurred. It did not allow for the fact that air traffic control generally obtain a pilot report of "leaving" a level before instructing that crew to transfer to the FIS frequency and that a pilot may wait up to one minute after leaving a level before making that report to air traffic control.

Crew of the Brasilia

Due to the short notice given to the pilot in command of the Brasilia about the Dash 8, he had to make a decision on whether to continue the descent. His choice to continue visually, even though he had not yet sighted the Dash 8 or made radio contact with the crew, was made when there was no separation assurance provided by the manoeuvre. However, the pilot in command of the Brasilia had sighted the Dash 8, while still in controlled airspace, and elected to continue descent on a "see and avoid" basis until radio contact was achieved.

This decision also meant that, due to the frequency congestion, the required broadcast on the FIS 7 frequency was not made until the Brasilia was outside controlled airspace.

Documentation

Aeronautical Information Publication

The AIP allows a pilot of an instrument flight rules aircraft to proceed on a "see and avoid" basis under visual flight rules when in visual meteorological conditions. These procedures were designed when the majority of aircraft were comparatively slow and operated at altitudes below 10,000 ft and may not be appropriate at 20,000 ft with aircraft closing speeds in the region of 500 knots. Whether this option should be allowed in all circumstances may need to be reviewed.

Manual of Air Traffic Services

The guidance for air traffic service officers in relation to traffic assessment in class "G" airspace was not specific in regard to the timely passing of traffic information and coordination. Judgement was left to the experience of individual officers and tended to vary from person to person.

An Embraer E120 (Brasilia) aircraft had departed from Cairns for Bamaga. The crew were maintaining flight level (FL) 220 in controlled airspace under the control of Brisbane Sector 10. They had reported their position as over Lockhart River at 1211 EST with an estimate for Bamaga of 1236. At about 50NM from Bamaga, the crew requested clearance to descend.

A de Havilland Dash 8 aircraft had departed Horn Island for Cairns at 1207 and the crew had reported to flight service (FIS 7) their intention to climb to FL210. The flight service officer instructed the crew to contact the Sector 10 controller when approaching controlled airspace for an airways clearance.

At 1220, the flight service officer passed traffic information regarding the Brasilia to the crew of the Dash 8.

At 1226, the controller instructed the crew of the Brasilia to leave the control area on descent and to report passing FL200, which was the base of controlled airspace in that vicinity. The crew commenced descent at that time and set up a rate of descent of 2,000 ft/min. Shortly after, the controller advised the crew that the Dash 8 aircraft was conflicting traffic for their descent and authorised them to transfer to the FIS 7 frequency.

The pilot in command was the handling pilot of the Brasilia while the co-pilot was performing the radio tasks. When they received a clearance to leave controlled airspace they commenced descent immediately and this action was followed by the receipt of traffic information regarding the Dash 8. The pilot in command quickly assessed that this traffic was in direct conflict and instructed the co-pilot to make a specific call to the crew of the Dash 8 as soon as he had transferred communications to the flight service frequency, rather than the general traffic call normally transmitted.

The co-pilot was waiting to report leaving FL200 as instructed by the sector controller. As a result of the instruction by the pilot in command, he made this report early using the phrase "approaching FL200" and selected the radio to the FIS 7 frequency as the aircraft was passing FL205.

Further delay was then experienced as the FIS frequency was congested. The aircraft was passing the base of controlled airspace and, as the weather was consistent with visual meteorological conditions (VMC), the pilot in command elected to continue visually rather than to level off in the control area. He was confident of seeing the Dash 8 and, in fact, saw the aircraft before the co-pilot could make his initial radio transmission on the FIS frequency.

At 1228, the crew of the Dash 8 contacted sector control for an airways clearance while passing FL188. The controller was unable to issue a clearance at that time because the altitude of the Brasilia was unknown and it was not clear if that aircraft had passed the Dash 8.

At the same time, the co-pilot of the Brasilia was attempting to contact the Dash 8 crew on the FIS 7 frequency to establish their respective altitudes. The crews eventually determined that the Dash 8 was climbing through FL190 while the Brasilia was descending through FL180. The Dash 8 crew had not seen the Brasilia but had seen a shadow pass over their aircraft. Having established that the aircraft had passed, the crew of the Dash 8 returned to the sector control frequency where they were cleared to enter controlled airspace on climb to FL210.

The point of conflict was outside of radar coverage but calculation indicated that the aircraft passed with no more than 2,000 ft vertical separation and no discernible horizontal separation.

1. Fog prevented the pilot from conducting a visual approach.
2. The pilot did not divert to a suitable aerodrome.
3. The pilot descended below the NDB approach minimum descent altitude without establishing visual reference with the runway.

The conduct of the flight suggests that the pilot may have been under pressure to complete the flight to Coonamble that evening. This was evidenced by:

1. The pilot's decision to continue to Coonamble rather than remain at Charleville overnight as earlier planned, despite receiving advice that the weather en route was not suitable for NVFR flight;
2. The pilot's decision to conduct an instrument approach at Coonamble, after deciding not to proceed to Dubbo when advised that weather conditions there required instrument approach procedures;
3. The decision to conduct an NDB approach at Coonamble after advising flight service that he was diverting to Walgett; and
4. The change in flight status to IFR and the pilot's advice to flight service that he was "IFR rated", although his instrument rating had expired.

There was no evidence that the pilot had rested at any stage after departing Longreach. Consequently, at the time of the accident, he had been awake for about 17 hours, half of which was flight time. The pilot may have been experiencing fatigue. The effects of fatigue can include a decreased level of performance in complex tasks, and lowering of an individual's ability to concentrate. These effects could have contributed to the pilot being slow to recognise, and to respond to, the aircraft's proximity to the ground.

It is possible that the pilot descended below the minimum altitude in an attempt to see the runway lights in order to land. To do so would have required that he divide his attention between flying the aircraft (by reference to the flight instruments) and looking outside the cockpit for the runway lights. This would have involved a high workload, and if the pilot's flight instrument scan was not adequate, a significant loss of altitude and associated increase in airspeed could have rapidly occurred.

The purpose of the flight was to convey two passengers from Coonamble to Longreach and then to two properties near Barcaldine, before returning to Coonamble. The flight departed Coonamble at about 1615, arriving at Charleville at 1835 for an overnight stop.

At 0619 the following morning, the aircraft taxied for Longreach and, at 0948, taxied for Coreena Station, arriving there at 1020. The flight subsequently continued to Barcaldine Downs Station, where the party was offered overnight accommodation. However, this was declined because rain, which may have affected serviceability of the property airstrip, was expected, and one of the passengers had commitments in Coonamble early the following day. The pilot indicated that they would fly to Charleville and remain there overnight. The aircraft arrived at Charleville at 1836 where a local commercial pilot refuelled the aircraft. He discussed the Charleville-Coonamble en-route weather with the pilot, indicating that, in his opinion, it was not suitable for night visual flight rules (NVFR) flight.

The aircraft departed Charleville at about 1925. The pilot notified flight service of the NVFR flight and arranged a SARTIME of 2150 for arrival at Coonamble. At about 2145, the aircraft was in the Coonamble area but the pilot reported that he was unable to see the runway lights. A pilot at the aerodrome terminal advised him that the runway lights were on but that there was thick fog present.

At 2204, the pilot informed flight service that he was proceeding to Dubbo and that the aircraft's fuel endurance was 200 minutes. At 2206, flight service advised the pilot that the Dubbo weather was not suitable for NVFR operations. At 2215, the pilot reported that he was diverting to Walgett. He did not request from flight service a weather forecast or report for Walgett or for any other location.

The direct track to Walgett from the aircraft's position at that time passed over Coonamble. The pilot reported at 2237 that he intended to conduct an instrument approach at Coonamble. In response to a query from flight service, the pilot confirmed that he was "IFR rated" [instrument flight rules rated]. He commenced the approach at about 2238. At 2239, the pilot reported that he was conducting the initial part of the approach in visual conditions and that he would then be in instrument flight conditions for the remainder of the approach.

A witness at the aerodrome terminal reported that thick fog was still present. He heard the aircraft fly low overhead before the noise changed, as if engine power had increased. He then heard the sound of an impact. The wreckage was located about an hour later, immediately west of the intersection of the sealed runway and the grass strip.

Pilot-in-command

The pilot-in-command had a total flying experience of 1,445 hours, of which about 450 were on Cessna 210 aircraft on low level survey tasks.

Aircraft information

The aircraft was manufactured in the USA in 1982 and was entered on the Australian register in 1983. In 1994, it was fitted with approved specialist equipment for geophysical survey operations. The certificate of registration and maintenance release was valid at the time of the accident. The weight and centre of gravity (CG) were within limits.

Meteorological information

A Bureau of Meteorology post-analysis of the weather conditions in the survey area at the time of the accident, indicated that the surface wind was easterly at 5-10 knots. The wind at 2,000 feet was 070 degrees at 25 knots, causing a wind shear of approximately 20 knots between that level and the surface. There was likely to have been significant mechanical turbulence in the Drummond Range area. There was a broken layer of stratiform cloud with a base of 2,000 to 3,000 feet. Visibility beneath the cloud was good and there was no evidence of precipitation in the area. Similar conditions existed on the day following the accident when search aircraft reported severe mechanical turbulence at low level in the area.

Position of the sun

Sunrise at the accident location was 0637. Between 0700 and 0800, the elevation of the sun was between 4 and 16 degrees above the horizon. The azimuth of the sun during that time was between 061 and 068 degrees M.

Examination of the wreckage

Evidence at the accident site indicated that the aircraft had struck several trees while in an 85-90 degree angle-of-bank descending turn to the right. The aircraft heading at that time was about 240 degrees M. Fifteen metres after the initial tree contact, the right wingtip struck the ground. The aircraft then cartwheeled before coming to rest inverted. The wings separated from the fuselage as a single unit and continued beyond the main wreckage. The fuselage remained substantially intact during the impact sequence but was destroyed by the post-impact fire.

Examination of the airframe and powerplant did not reveal any abnormality that might have contributed to the accident. The nature and extent of damage to the propeller indicated that the engine was producing power at impact. The wing flaps were in the retracted position and there was no evidence that the aircraft had suffered a birdstrike. The extent of damage to the survey equipment on the aircraft precluded the recovery of any recorded data that might have assisted in determining the flight path of the aircraft.

Medical and pathological information

There was no evidence of any physiological condition concerning either crewmember that may have contributed to the accident.

Survival aspects

The severity of the impact and subsequent fire were such that the accident was not survivable.

Emergency locator transmitters

The aircraft carried two emergency locator transmitters. One of these was a fixed installation and the other was a portable unit that was normally located under the crewmember's seat. Both units were recovered. The nature and extent of damage sustained by each precluded normal operation.

Other information

Pilot training

At the time of the accident, there was no regulatory requirement which specifically addressed low level survey operations. However, the instrument of approval for low level survey operations issued to the company by the Civil Aviation Safety Authority (CASA) required pilots employed by the company to have either undergone a course in low level flying, or to hold or have held an agricultural rating or an aerial stock mustering approval. This was standard CASA procedure for such approvals.

Civil Aviation Order (CAO) 29.10 addressed low level flying for aerial stock mustering operations. Appendix 1 to the order detailed the syllabus of training. Paragraph 2 referred to aeroplanes and gyroplanes and stated:

1. Aircraft Handling:
   1. level, climbing and descending turns up to 60 degrees angle of bank;
   2. review of stalling symptoms and recovery in both wings level and turning flight up to 60 degrees angle of bank (Aeroplanes);
   3. recovery from high rates of descent at speeds below minimum straight and level speed (Gyroplanes)
   4. slow flying (including use of flap and the effect of changing flap settings);
   5. methods of losing height;
   6. manoeuvring at varying airspeeds and angles of bank.
   7. Note: Before starting low flying training the student is to demonstrate safe aircraft handling of sub-paragraphs (i), (ii), and (iv) below 300 feet but not below 150 feet.
2. Low Flying:
   1. low flying (below 100 feet above ground level);
   2. slow flying (including use of flap);
   3. effect of wind (apparent change in speed in head/tail winds and apparent slip and skid in cross winds);
   4. action in the event of engine failure at low level;
   5. method of losing height;
   6. procedure turns, steep and climbing turns from a fixed ground reference combined with descending turns back to the reference. The obstructed viability inherent in manoeuvring high-wing aeroplanes in descending turns to be a fixed ground reference shall be demonstrated;
   7. low flying in hilly terrain;
   8. effect of false horizons;
   9. effect of the sun, under certain conditions, on visibility;
   10. approach to high ground - use of escape routes; and
   11. avoidance of obstacles."

The pilot's records indicated that he had completed sub-paragraph (a) "Aircraft Handling" training in August 1995. This indicated that the pilot had completed the section of the syllabus relating to aircraft handling. There was no record of him having completed the sub-paragraph (b) "Low Flying" section of the syllabus.

Additional information and training provided by the company to pilots

The survey company issued to all its pilots, a publication titled "The Survey Pilots Guide". The guide outlined the techniques and procedures to be used when flying survey operations. Some of the topics covered included hazards such as the sun, terrain, and powerlines. Paragraph 3.1.4 of the Guide addressed "Terrain". Paragraph 3.1.4(b) was titled anticipation and stated:

"Due to the aircraft's speed and inertia it is vital to anticipate commencement of climb and descent when following terrain. Terrain over 1,500 feet above normal survey level needs further anticipation as the inertia dissipates above this height, the aircraft relies on climb performance alone. For example approaching a hill of 2,500 feet commence climb at five nautical miles before the base of the hill."

Paragraph 3.1.4(a) stated that "kinetic energy of the aircraft provides some assistance when flying over terrain up to 1,500 feet above ground level".

There was no information in the guide, nor was there training provided to pilots, on specific manoeuvres such as minimum radius turns which might need to be flown as an escape manoeuvre from a valley.

For any aircraft flying at an airspeed of 140 kts, the radius of turn for a constant altitude, steady turn, is as follows:

The elevation of the wreckage was between 2,100 ft and 2,250 ft above mean sea level. The width of the valley at this elevation was between 500 and 850 m. The valley width at 2,000 ft elevation was 300 m, and reduced to about 200 m at 1,800 ft elevation.

The factors contributing to this accident could not be conclusively determined.

In the absence of any witnesses or recorded flight data, the events leading to the accident could not be determined. However, the right turn the aircraft was apparently performing at impact could indicate that the pilot had been flying towards the northeast, into the valley (perhaps following survey line 11124) and was attempting to turn back down the valley. It is possible that the wind and turbulent conditions in the valley affected the climb performance of the aircraft sufficiently to create doubt in the pilot's mind that the aircraft possessed enough residual performance to outclimb the valley floor.

Cloud on the range may have affected visibility and limited or delayed the pilot's appreciation of the terrain ahead. Similarly, if the weather was clear, the elevation and azimuth of the sun relative to the aircraft's track may also have affected the pilot's perception of the terrain ahead. Either of these possibilities may have caused him to attempt to turn back.

The outcome of a turn in the valley would have depended on the aircraft's speed and altitude when the turn was initiated, its position in the valley (that is, the manoeuvring area available), and the pilot's skill level, as well as any turbulence and/or windshear which was present. A comparison of turn radii at various bank angles against the width of the valley indicates that the aircraft could have been in a position where there was insufficient room in which to safely complete a turnback.

The completion by the pilot of only the "Aircraft handling" section of the Aerial Stock Mustering Syllabus may have influenced his actions in the events leading to the accident. However, the limited information available concerning the final stages of the flight made any meaningful assessment in this regard impossible.

The Cessna 210 was involved in a geophysical survey task west of Emerald. The survey task included flying a number of pre-planned survey lines. A line number identified each line. The survey lines to be flown on the day of the accident were a block between lines 11118 and 11125. Line 11127, south of this block, was to be re-flown as previous data collected on the line was flawed. The lines were oriented 070/250 degrees M and were about 110 km (60 NM) long. From the southwest, the lines traversed flat, open terrain initially, and then crossed the Drummond Range. The range rises about 400 m above the level of the surrounding terrain and is a rugged area, which includes a number of narrow valleys.

The aircraft was equipped with a satellite navigation system, which provided information on the track to be flown to the pilot via a display on the glare-shield above the instrument panel. A radio altimeter provided aircraft height above ground level. Survey lines were to be flown at 140 kts indicated airspeed and, where possible, at 80 m above ground level. Accuracy in horizontal track keeping had priority over vertical navigation accuracy. For considerations of safety and ease of flying, the flying technique over rough terrain involved "smoothing" of the flight path rather than attempting to follow terrain contours.

The aircraft departed Clermont at 0638 EST. Because radio transmissions interfered with the recording of survey data, none were normally made during survey operations. Consequently, no contact was expected from the aircraft until about 1130, when it was due to return from the survey task. When no communication had been received by this time, the company reported that the aircraft was overdue and a search was commenced. Three days later, the burnt wreckage of the aircraft was located in the Drummond Range approximately 58 NM west of Emerald. The wreckage was about 30 m below the top of a ridge, which formed the southern side of the same valley followed by survey line 11124. It was approximately 400 m south of that line.

There were no witnesses to the accident.