Summary

On Sunday 24 April 1994, at about 0910 EST, Douglas DC-3 aircraft VH-EDC took off from runway 16 at Sydney (Kingsford-Smith) Airport. The crew reported an engine malfunction during the initial climb and subsequently ditched the aircraft into Botany Bay. The DC-3 was on a charter flight to convey a group of college students and their band equipment from Sydney to Norfolk Island and return as part of Anzac Day celebrations on the island. All 25 occupants, including the four crew, successfully evacuated the aircraft before it sank.

The investigation found that the circumstances of the accident were consistent with the left engine having suffered a substantial power loss when an inlet valve stuck in the open position. The inability of the handling pilot (co-pilot) to obtain optimum asymmetric performance from the aircraft was the culminating factor in a combination of local and organisational factors that led to this accident. Contributing factors included the overweight condition of the aircraft, an engine overhaul or maintenance error, non-adherence to operating procedures and lack of skill of the handling pilot.

Organisational factors relating to the company included:

• inadequate communications between South Pacific Airmotive Pty Ltd who owned and operated the DC-3 and were based at Camden, NSW and the AOC holder, Groupair, who were based at Moorabbin, Vic.;
• inadequate maintenance management;
• poor operational procedures; and
• inadequate training.

Organisational factors relating to the regulator included:

• inadequate communications between Civil Aviation Authority offices, and between the Civil Aviation Authority and Groupair/South Pacific Airmotive;
• poor operational and airworthiness control procedures;
• inadequate control and monitoring of South Pacific Airmotive;
• inadequate regulation; and
• poor training of staff.

During the investigation, a number of interim safety recommendations were issued by the Bureau. These recommendations, and the CAA's responses to them, are included in this report.

FACTUAL INFORMATION

Circumstances

The pilot of the Piper Aztec submitted flight plan details by telephone to Cairns Tower for a visual flight rules (VFR) charter flight from Cairns to Palm Island via Innisfail. The plan indicated an initial track of 153 degrees M at an altitude of 5,000 ft.

The aircraft departed Cairns at 0946 hours EST and the pilot advised Cairns Approach that he was tracking on the

153 omni radial from Cairns. At 0954.35 he reported maintaining 5,000 ft. At 0956.02 a regular public transport (RPT) aircraft inbound to Cairns from the south reported approaching 7,000 ft and was subsequently cleared to descend to 6,000 ft. At 0956.59, after the potential confliction with the Aztec was resolved, the RPT aircraft was cleared to descend to 4,100 ft. At this time the Aztec was 23 NM from Cairns at 4,600 ft and about 2 NM right of track. A short time later the approach controller noticed that the radar returns from the Aztec had ceased.

Terrain in the area is known to cause shielding and the loss of radar returns. The controller assumed that shielding had caused the Aztec to disappear from radar so he instructed the pilot of the Aztec to call the area flight service frequency, as there was no further requirement to remain on the approach frequency. No reply to this transmission was received and this was also thought to be due to terrain shielding. A short time later other aircraft in the area reported the operation of an emergency beacon. A distress phase was initiated, and the wreckage of the Aztec was subsequently located on the western side of a blind valley north-west of Bellenden Ker Centre Peak at about 4,200 ft above mean sea level (AMSL) by a search helicopter.

Examination of the recorded radar data indicated that the aircraft gradually drifted right of track during the climb to 5,000 ft. At top of climb, some 15 NM south of Cairns Airport, it was about 0.75 NM right of track. At around this point, the track deviated further right by about 12 degrees. This track remained relatively constant until the aircraft was about 24 NM from Cairns where it again turned right. The aircraft maintained 5,000 ft to about 19 NM from Cairns after which it descended to 4,800 ft and remained between 4,800 and 4,700 ft until about 23 NM from Cairns. From this position it commenced further descent which continued for about 1 minute until the radar return ceased at a recorded altitude of 4,200 ft. During the descent the computed groundspeed of the aircraft decreased from 137 kt to 105 kt.

Examination at the accident site indicated that the aircraft struck the rainforest canopy at 4,200 ft AMSL with a descent angle of about 8 degrees and banked about 22 degrees to the right. The aircraft track at impact was about 196 degrees M.

Wreckage Examination

Examination of the aircraft wreckage did not reveal any abnormality which might have contributed to the accident.

Other than a complete set of Instrument Approach and Landing Charts, no other maps or charts were found in the wreckage. 

The Pilot

The pilot held a commercial pilot licence and was endorsed to fly PA-23 aircraft. Although his instrument rating had expired, he had conducted some instrument flying practice during the day prior to the accident.

The pilot had only limited flying experience in the Cairns area. This experience consisted of a short check flight at Cairns on 27 February 1994, a flight from Palm Island to Cairns on 17 March 1994, and two check flights at Cairns on 17 and 18 March 1994. The accident flight was the first recorded occasion of the pilot flying from Cairns to another destination.

The aircraft operator indicated that the pilot had not been given any specific briefing on the Cairns area as he considered that a pilot with 4,500 flying hours experience would not require such a briefing.

The post-mortem examination revealed some coronary artery occlusion which was considered to be too minor to have adversely affected the performance of the pilot.

Weather

The weather forecast for the area indicated a fresh to strong south-easterly airflow over the area with isolated showers over the coast and ranges. Broken stratus cloud was forecast from 1,000 to 3,000 ft in precipitation, along with scattered cumulus from 2,000 to 10,000 ft. Rain showers with 4 km visibility and occasional moderate turbulence below 7,000 ft near the ranges were also forecast.

The weather recorded on the Cairns Automatic Terminal Information Service (ATIS) at 0849 was wind 160 degrees M at 10-15 kts, temperature 25 degrees C, two oktas of cloud at 2,500 ft with lower patches and three oktas at 3,500 ft. There were showers in the area. Cairns Tower controllers stated that the top 500 ft of Mt Bellenden Ker appeared to be covered by cloud around the time of the accident.

Operating requirements

Aeronautical Information Publication (AIP) Australia RAC - 50a para 43.5.1 addresses flight under the VFR. The requirements include, inter alia:

1. the pilot in command of a VFR flight in controlled airspace must navigate by visual reference to the ground or water; and
2. when operating at or below 2000 ft above the ground or water, the pilot in command must be able to navigate by continuous visual reference to the ground or water or by the use of approved radio navigation apparatus as specified in CAO 20.8.

Under the VFR, AIP RAC - 33 requires that for the track being flown by the accident aircraft, the appropriate altitude would have been odd thousands of feet plus 500 ft for example 5,500 ft or 7,500 ft.

RAC CTL - 1 para 14.1 states, inter alia that a pilot must not deviate from track or change level without obtaining ATC approval when in controlled airspace.

The Approach Controller's duties included a requirement to maintain general radar surveillance of his area of responsibility insofar as the performance of other functions permitted. As part of this monitoring function, the controller was required to advise the pilot of a radar identified aircraft when that aircraft was observed to deviate beyond the normal navigational tolerance from the intended track. This tolerance is defined in the Manual of Air Traffic Services (MATS) as plus or minus 2 NM when an aircraft is 2,001 to 5,000 ft AGL and is navigating by visual tracking and position fixing.

MATS indicates that assigned cruising levels shall whenever practicable be in accordance with the level selected by the pilot and assigned levels shall normally conform to the appropriate table of cruising levels. Levels not conforming to these tables may be assigned when air traffic or other circumstances require. Prior to assigning an aircraft a non-standard level the controller shall consider workload and coordination implications along with the effect on aircraft already operating at standard levels.

Air Traffic Control

After the pilot had reported maintaining 5,000 ft he did not request a clearance to descend or alter heading.

A significant proportion of air traffic in the Cairns area operates in the VFR category. These flights often operate in an environment involving inclement weather and high terrain. The Cairns air traffic controllers reported that, particularly during the wet season (December-March), local weather conditions are frequently such that aircraft operating VFR are required to deviate from track to remain clear of cloud or avoid high terrain.  In this environment the controllers become accustomed to aircraft operating adjacent to high terrain or deviating off track and it is not unusual for radar and radio contact with VFR aircraft to be lost because of terrain shielding.

The final 30 seconds of VH-BOC's descent were observed by a supervising controller who was randomly monitoring a radar screen in the control tower. On seeing the radar return from VH-BOC disappear he immediately returned to the Approach Control Centre to check the status of the aircraft, which by this time was no longer in radio contact.

Flight Planning

The pilot was not asked by the briefing officer or the air traffic controller why he chose to fly at 5,000 ft. No explanation was found as to why the pilot chose to fly the route at 5000 ft. There was no requirement for air traffic control to query the cruise altitude nominated by the pilot even though the controllers were aware that 5000 ft was not normally used by VFR traffic in the area. Aircraft operating in the VFR category in the Cairns area normally cruise below 2,000 ft or above 6,500 ft due to the prevalence of cloud on the ranges.

ANALYSIS

The recorded radar data showed a distinct change in aircraft track at about 16 NM from Cairns shortly after top of climb.  The forecast winds were fairly constant from 2,000 ft to 7,000 ft so the track change seems unlikely to have been due to wind. It is possible that the pilot deliberately altered heading towards the blind valley west of Bellenden Ker Centre Peak in an attempt to avoid the deteriorating weather conditions along the intended track.

The descent pattern flown by the aircraft could also indicate that the pilot was manoeuvring the aircraft to remain clear of cloud. Having limited familiarity with the area and apparently no topographical maps on board the aircraft the pilot was not well placed to safely navigate the aircraft. The final descent and right turn made by the aircraft were possibly an attempt to remain clear of cloud.

Once VH-BOC had passed the inbound regular public transport traffic, when traffic separation considerations were no longer a factor, ongoing surveillance of the aircraft reverted to becoming part of the controller's normal monitoring function. A number of considerations influenced the controller's subsequent monitoring of the aircraft. There was other traffic, including IFR traffic, under the controller's jurisdiction which required his attention. The aircraft remained within 2 NM of the Cairns-Innisfail track until about one minute 30 seconds before radar contact was lost. The aircraft was not significantly beyond 2 NM right of track until 30 seconds or so before radar contact was lost. Because of the terrain and weather conditions generally prevailing in the Cairns area, controllers can in effect, become desensitised to track and altitude deviations by aircraft operating in the VFR category.

Had the pilot reported to ATC that he was deviating to the right of track and/or descending or that he was experiencing difficulties with weather conditions, he would have alerted the controllers and been provided with navigation assistance.

CONCLUSION

Significant factors

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

1. The pilot was not familiar with the area.
2. The pilot apparently did not have with him in the aircraft any relevant topographical maps or charts covering the route being flown.
3. The pilot did not advise air traffic control that he was deviating from track and/or descending nor that he was encountering weather difficulties.

1. FACTUAL INFORMATION

Sequence of events

On the day before the accident, the aircraft flew from Aurukun to Weipa with the chief pilot occupying the left pilot seat and the pilot involved in the accident occupying the right pilot seat. At Weipa the chief pilot left the aircraft, instructing the other pilot to fly some practice circuits before returning the aircraft to Aurukun. Before commencing the circuits and the return flight to Aurukun, the aircraft's two main tanks each contained 100 L of fuel and the two wing tip tanks each contained about 90 L of fuel.

On the day of the accident the pilot added 200 L of fuel at Aurukun to the aircraft's tanks and then flew the aircraft and the passengers to Weipa. About 50 minutes before sunset, the aircraft taxied for departure from runway 30 for the 25-minute return flight to Aurukun.

When the aircraft was about 300 ft above ground level after take-off, a witness reported that all engine sounds stopped and that the aircraft attitude changed from a nose-high climb to a more level attitude. A short time later, the noise of engine power surging was heard. The aircraft rolled left and entered a spiral descent. It struck level ground some 350 m beyond the departure end of runway 30 and 175 m to the left of the extended centreline.

Wreckage examination

The aircraft had impacted the ground in a 30-degree nose-down attitude with 45 degrees of left bank. The left wing was broken at mid-span. The cockpit and forward cabin were totally crushed back to the leading edges of the wings.

The right propeller had gouged a deep hole in the soil and the propeller blades were bent both against the direction of rotation and rearwards toward the engine, indicating that this engine was producing considerable power at impact. The right fuel distributor valve contained fuel.

The left propeller was in fine pitch. One blade was bent rearwards toward the engine and the other blade was undamaged. Part of the spinner was crushed and part of it was almost intact. This damage pattern indicates that the left engine had stopped before impact. The left fuel distributor valve contained little fuel.

The left engine was removed from the aircraft and dismantled. No pre-impact damage that would have prevented the engine from operating was found.

Inspection of the airframe and other systems did not reveal any faults which might have contributed to the accident.

Fuel system

The aircraft had been fitted with the manufacturer's wing tip tank modification. Each tip tank had a useable capacity of 104.5 L and each main tank a useable capacity of 240 L. A flight manual supplement detailing the operation of this fuel system had been issued and incorporated in the flight manual. The fuel management section of this supplement indicates that, for structural reasons, fuel from the tip tanks must be used last, and that 50 L should be retained in each tip tank unless the fuel is needed for holding or diversion to another airfield. There is a warning in the flight manual supplement that take-offs and landings on main tanks are prohibited when the gauges read less than three gallons (about 14 L). There is no corresponding warning for the tip tanks.

Examination of the tip tanks showed that the fuel feed line was located centrally at the inboard tank baffle/outer wing rib near the bottom of the tank. The two main fuel selectors in the cockpit had moved from main fuel cock selection when the cockpit area was crushed during the main impact. However, examination of the fuel system confirmed that the main fuel cocks were open.

Toggle switches which control the main/tip tank selection were destroyed during impact. However, the light globes from the fuel tank indicators were examined and these indicated that the tip tanks were selected at the time of impact. Further inspection of the fuel supply system confirmed that the electrically actuated tip tanks fuel cocks were selected to draw fuel from the tip tanks.

The left tip tank was ruptured and separated from the wing. It contained about 5 L of fuel. The right tip tank was partially separated and did not contain any fuel. Reports from people at the scene immediately after the accident indicated that a large amount of fuel from the ruptured main tanks was present at the site.

The pilot

Six weeks before the accident, the pilot completed his endorsement training on an Islander aircraft which was not fitted with the tip tank modification. However, the endorsing instructor had briefed the pilot on the various fuel systems encountered in the Islander family of aircraft, including the particular wing tip tank modification fitted to VH-JUU. After his endorsement the pilot flew VH-JUU for a total of 3.6 hours until the day before the accident. The duration of the flight on the day before the accident, together with that of the passenger flight to Weipa on the day of the accident, was approximately one hour and twenty minutes. Therefore, at the time of the accident, the pilot had a total of 6.7 hours on the aircraft type.

Passengers and freight

The purpose of the flight was to collect cartons of beer from Weipa. The Aurukun Community had a policy of allowing a maximum of ten cartons to be carried on any one charter flight. However, sometimes passengers would insist on carrying more. The aircraft wreckage contained 30 cartons of beer and two bottles of rum, the latter being totally prohibited by the community. The cartons had been packed on and around seat rows four and five. The load had not been tied down. The aircraft gross weight was calculated to have been 47 kg below the limit for this take-off. The centre of gravity was within limits.

Checklist

The endorsing instructor had given the pilot an Islander checklist. The aircraft usually carried a normal procedures checklist on a clipboard, but this was inadvertently left at Aurukun. A checklist for normal procedures was not found in the wreckage although an emergency procedures checklist was found incorporated in the flight manual carried on board.

Fuel management

For planning purposes on this flight, the flight manual indicated a fuel consumption rate of 135 L per hour. The chief pilot reported that when he handed the aircraft over to the pilot at Weipa on the day before the accident there was about 90 L in each tip tank and that the tip tanks were probably selected to provide fuel to each engine.

2. ANALYSIS

If the tip tanks were selected since the previous day, the tip tank fuel contents should have been exhausted at about the time of the final take-off from Weipa. With a low quantity of fuel in each tip tank, the fuel lines from each tank probably became unported as the aircraft climbed after take-off, resulting in engines losing power from fuel starvation. When the pilot changed the attitude of the aircraft after the loss of power, some fuel probably became available to the right engine which then regained power.

Other factors include the pilot's low level of experience in the aircraft type, the absence of a normal procedures checklist and pressure from the passengers to complete the return flight with the excess alcohol. This pressure may also have accounted for the freight not being correctly secured.

A double, simultaneous engine failure was probably outside the pilot's experience level. A forced landing option was available which would have necessitated the closing of both throttles and landing on the Weipa-Coen road, which cut across the extended centreline of the runway at an angle of about 30 degrees. However, once the aircraft entered a spiral descent at low speed and with asymmetric power, recovery was not possible in the height available.

3. CONCLUSIONS

Findings

The aircraft was being operated within weight and centre-of-gravity limits.

No defects that were likely to have contributed to the occurrence were found with the aircraft.

The aircraft's wing tip tanks were selected to feed fuel to the engines.

The right engine was producing considerable power at impact.

The left engine had stopped before ground impact and the propeller was not feathered.

The pilot did not operate the aircraft fuel system in accordance with flight manual instructions.

Both engines were starved of fuel during the initial climb after take-off.

The pilot had probably operated the aircraft exclusively on fuel from the wing tip tanks, which were near empty at take-off.

A suitable forced landing option was available.

There was no warning in the aircraft flight manual to alert the pilot to the danger of operating with near empty wing tip tanks.

Following the entry into the spiral there was insufficient height available for a recovery to controlled flight. Significant factors

The pilot mismanaged the aircraft fuel system.

Both engines suffered a total power loss due to fuel starvation.

The right engine regained power probably as a result of a change in aircraft attitude.

The pilot lost control of the aircraft.

Recovery was not possible in the height available.

4. SAFETY ACTION

During the course of this investigation Interim Recommendation IR 940193 was issued. It stated:

The Bureau of Air Safety Investigation recommends that the Civil Aviation Authority review the approval for the Flight Manual Supplement pertaining to wingtip fuel tanks on BA-2A-21 aircraft. Consideration should be given to adding suitable warnings that the use of partially filled wingtip tanks during take-off, landing and manoeuvring may lead to fuel starvation.

The following response, dated 8 November 1994, was received from the CAA:

"The Interim Recommendation on the aircraft has been reviewed and action in line with the BASI recommendation is being taken to update the aircraft flight manual."

The pilot had been authorised to carry out a night-VFR flight in the Maitland training area on 19 March. That evening VH-RNN was observed to depart Maitland and later in the evening the pilot was seen in his car in the airport carpark. The following morning witnesses observed an unidentified aircraft flying in a northerly direction below low cloud on the eastern side of the F3 freeway, approximately 105 km south of Maitland. The aircraft was subsequently observed to bank steeply to the left and appeared to descend before disappearing from view. The wreckage of VH-RNN was subsequently found on 30 March, near the F3 freeway, about 800 m south of the earlier sighting of the unidentified aircraft.

Toxicological analysis of the pilot revealed the presence of the drug Dextropropoxyphene at levels which may have caused him to experience sleepiness, hallucinations, delusions and confusion during the flight.

The pilot's intentions could not be established. The aircraft was observed manoeuvring in conditions of low cloud and reduced visibility and it is likely that the pilot was attempting to turn back to an area of more favourable conditions. The pilot's ability to remain safely clear of terrain may have been adversely affected by the effects of the drug Dextropropoxyphene.

Significant Factors

1. The aircraft was operating at a low height in conditions of low cloud and reduced visibility.
2. The pilot's ability to safely control the aircraft may have been adversely affected by an analgesic drug.

SYNOPSIS

The aircraft was engaged on a freight courier service and had departed Bankstown at 0630 EST on 9 March 1994 and proceeded to Tamworth, Armidale, Glen Innes and Inverell. The pilot rested at Inverell for approximately seven hours before departing at about 1640 on the return flight to Bankstown via Glen Innes, Armidale and Tamworth. The flight was planned to be conducted in accordance with the Instrument Flight Rules (IFR) and departed Armidale for Tamworth at 1723. At about 1734 the aircraft impacted a mountain 8.2 NM north-east of Tamworth at 2,685 ft above mean sea level (AMSL), after being cleared to make a visual approach by Tamworth Tower. A short time after the accident, the pilot of a search aircraft observed that the top of the mountain was obscured by cloud.

1. FACTUAL INFORMATION

1.1   History of the flight

VH-SWP was operating on a standard company flight plan for the route Bankstown-Tamworth-Armidale-Glen Innes-Inverell and return, and the flight plan indicated the flight would be conducted in accordance with IFR procedures. The classification of the flight was shown as non-scheduled commercial air transport although the aircraft was operating to a company schedule, and departure and flight times for each route segment were indicated on the flight plan.

The aircraft departed Bankstown at about 0640 and proceeded as planned to Inverell where the pilot rested until his departure that afternoon for the return journey. The schedule required an Armidale departure at 1721. At 1723 the pilot reported to Sydney Flight Service that he was departing Armidale for Tamworth. The planned time for the flight was 17 minutes.

Although the flight-planned altitude for this sector was 6,000 ft, the pilot was unable to climb immediately because a slower aircraft, which had departed Armidale for Tamworth two minutes earlier, was climbing to that altitude. In addition, there was opposite direction traffic at 7,000 ft. The next most suitable altitude was 8,000 ft, but separation from the other two aircraft, which were also IFR, had to be established by the pilot before further climb was possible. The published IFR lowest safe altitude for the route was 5,400 ft.

The pilot subsequently elected to remain at 4,500 ft in visual meteorological conditions (VMC) and at 1727 requested an airways clearance from Tamworth Tower.  A clearance was issued by ATC to the pilot to track direct to Tamworth at 4,500 ft visually. At about 1732 the pilot requested a descent clearance. He was cleared to make a visual approach with a clearance limit of 5 NM by distance measuring equipment (DME) from Tamworth and was requested to report at 8 DME from Tamworth. The pilot acknowledged the instructions and reported leaving 4,500 ft on descent. Transmissions from ATC to the pilot less than two minutes later were not answered. The aircraft was not being monitored on radar by ATC, nor was this a requirement.

At about 1740, reports were received by the police and ATC of an explosion and possible aircraft accident near the mountain range 8 NM north-east of Tamworth Airport. The aircraft wreckage was discovered at about 2115 by searchers on the mountain range.

Soon after the aircraft was reported missing, a search aircraft pilot, who had extensive local flying experience, reported to ATC that the top of the range (where the accident occurred) was obscured by cloud, and that there was very low cloud in the valley nearby.

1.2    Damage and impact information

The aircraft was on the Armidale to Tamworth track 8.2 NM from Tamworth when it impacted trees at approximately 2,685 ft AMSL. It was descending at an angle of approximately 3.5 degrees and was banked about 17.5 degrees to the left at impact. The aircraft maintained a straight path after initial impact but had rolled to a bank angle of 25 degrees left by the time the left wing struck a second tree 35 m further on. It then impacted the ground left wing low and inverted, before bouncing into a rock face 200 m from initial impact. The main fuselage wreckage caught fire, and the cabin area was destroyed.

1.3    The pilot

The pilot was 24 years old and was correctly qualified and endorsed to perform the flight. He had flown on the two days prior to the accident following three days off duty. He had not flown this route before. He completed a flight check on 28 October 1994 and his performance was assessed as satisfactory. The flight check report stated that the requirement to be aware of terrain at all times was reviewed with the pilot.

The pilot was not known to be suffering from any ailment and appeared to be in good spirits on the day of the accident.

1.4    The aircraft

1.4.1    Aircraft history

The Swearingen SA226-AT aircraft was manufactured in 1975. The Australian certificate of airworthiness was issued on 15 May 1986. The last periodic inspection was completed on 11 January 1994.

1.4.2    Weight and balance

The aircraft weight and balance (centre of gravity) were within limits for the flight.

1.4.3   Aircraft serviceability

There were no known unserviceabilities other than the windscreen wipers. When the aircraft arrived at Tamworth in the morning it was raining, and the aircraft was cleared to land on runway 30 right. During the approach the pilot made a comment to the aerodrome controller (ADC) to the effect that it was difficult to see out of the aircraft without the windscreen wipers working. Why the windscreen wipers were not working, or when they became unserviceable, could not be determined. Effective use of the windscreen wipers would not have been possible at the speed at which the aircraft was flying immediately prior to the accident.

1.5    Wreckage examination

1.5.1    Structure

All aircraft extremities and control surfaces were accounted for at the accident site. The damage sustained was consistent with the application of excessive loads during the accident sequence and subsequent fire. There was no evidence found of in-flight fire. As far as could be determined there was no pre-impact abnormality with the structure and all damage was a result of impact forces.

1.5.2    Flight controls

All control systems were examined although only portions of control surfaces were recovered. Where found, the hinges, push-pull rods and cables were correctly assembled and secured. Witness marks indicated that at the time of wing impact with the trees, the aileron was in a neutral position, aileron trim was neutral, and flaps were in the up position.

1.5.3    Landing gear

All major components of the landing gear system had been torn from the aircraft, and it was not possible to determine if the individual legs were up or down. However, the hydraulic actuators which remained attached to the right wing were in a position consistent with the right gear being in the retracted position 

1.5.4    Other systems

Due to the extent of destruction of the aircraft, the functional status of its systems, including the fuel, electrical, and pitot-static systems, could not be determined. 

1.5.5    Crashworthiness

The amount and nature of aircraft destruction indicated that the aircraft approached the accident site at high speed. The cockpit area was destroyed. Examination of the pilot's seat and harness indicated that although the shoulder harness had not been fastened at the time of impact, the impact dynamics were such that the accident was non-survivable.

1.6   Meteorological information

A low-pressure system was situated near Albury NSW with a central pressure of 1,010 hectopascals (hPa). A weak trough extended from the low into Queensland. A high-pressure system with a central pressure of 1,028 hPa was centred in the Tasman Sea. The resulting airstream was a very moist northerly to north-easterly flow with extensive low cloud over the north-eastern regions of New South Wales.

The information being broadcast on the Tamworth Automatic Terminal Information Service (ATIS) at the time of the accident indicated that the weather at Tamworth airport included a light and variable wind, two octas of cloud at 1,000 ft, with visibility reducing to 3,000 m in rain.

The pilot of a search aircraft which was in the area about 20 minutes after contact was lost with VH-SWP said that the general cloud base was about 2,200 ft with lower patches. He said he had climbed above the cloud and found the tops at 2,800 ft, with some higher patches to about 3,100 ft. The higher patches were obscuring the terrain. There was a higher layer of cloud with a base at about 3,800 ft. He could not see towards Armidale as it seemed as though the two layers converged. From the accident area he could see Tamworth easily and visibility in that direction was good. When the same pilot later ascertained where the accident occurred, he confirmed that the area of the accident site had been covered by wispy cloud when he flew over it shortly after the accident.

1.7   Additional information

1.7.1   Recorded radar data

The aircraft was under radar coverage from Armidale to a point approximately 2.5 NM from the accident location. The recorded radar data showed that the aircraft departed Armidale (runway 05) and turned left to intercept the Armidale-Tamworth track. The aircraft climbed initially to 5,000 ft but then descended to 4,500 ft and maintained this altitude until about 1731 when it climbed to 4,900 ft. (Its position at that time coincided with Mt Gulligal which is 4,070 ft AMSL.) The radar data showed the aircraft leaving 4,500 ft at 1732:40, which was the time the pilot received descent clearance. The last recorded altitude was 3,900 ft when radar contact was lost at about 10 NM from Tamworth. The computed aircraft ground speed at that position was 260 kts.

1.7.2   Air-ground communications

Automatic voice recordings of air-ground and air-air communications indicated that satisfactory two-way communications existed in the period leading up to the accident.

2. ANALYSIS

Other traffic on the Armidale-Tamworth route delayed the pilot of VH-SWP from climbing to his planned altitude of 6,000 ft. As a result, he apparently elected to remain at 4,500 ft and conduct the flight in VMC. When the pilot called Tamworth Tower, he reported being visual at 4,500 ft, and was given a clearance to track direct to Tamworth in visual conditions at 4,500 ft before being cleared for a visual approach. The accident site was observed to be covered by cloud shortly after the accident. It is possible, therefore, that the pilot inadvertently entered cloud and failed to remain in visual contact with the ground.

3. CONCLUSIONS

3.1    Findings

1. The pilot was correctly endorsed and qualified to undertake the flight, and the flight was operating in accordance with the scheduled departure time from Armidale.
2. The flight was planned to be conducted under the instrument flight rules but because of other traffic it was not expedient to climb to an appropriate altitude.
3. The flight was conducted at 4,500 ft, apparently under the visual flight rules.
4. The pilot reported that he could remain visual and was cleared by ATC to make a visual approach.
5. The aircraft was not being monitored on radar by ATC, nor was this a requirement.
6. The last recorded radar data showed the aircraft descending through 3,900 ft, 2.5 NM from the accident site.
7. There was low cloud and rain in the area at the time of the accident.
8. The pilot allowed the aircraft to descend into terrain for reasons which could not be determined.
9. No evidence was found of any physiological impairment of the pilot or of aircraft defects which may have contributed to the accident.

3.2   Significant factors

1. The pilot was making a visual approach in weather conditions unsuitable for such an approach.
2. The pilot had not flown this route before.
3. The aircraft was flown below the lowest safe altitude in conditions of poor visibility.

The pilot, accompanied by a young employee, departed Cowarie Station airstrip at about 0730 CSuT to carry out an aerial inspection of the property.

The pilot's wife was in the habit of maintaining contact with the aircraft at regular intervals using a CB radio.  When the pilot failed to respond to a scheduled call at 1000 CSuT she became worried and contacted relatives and friends for advice.  She continued making calls at 15 minute intervals, but without response. The police were notified and an aerial search initiated.  The aircraft wreckage was found at 1820.  The pilot had received fatal injuries, and the employee seriously injured.  The time of the accident cannot be determined, but probably prior to 1000 CSuT.

The aircraft, while flying on a heading of about 100 degrees, had struck a tree approximately 30 feet above ground level with the right wing, which separated causing the aircraft to roll inverted and impacted the ground in a nose low attitude about 100 metres from the tree.

An inspection of the aircraft by the police officer at the accident site revealed that all seats except that of the pilot were missing.  They were later found in the property hangar.  He also found a green garbage bag in the aircraft containing numerous small pieces of meat resembling dog baits, with other similar size pieces of meat lying nearby.

A certain amount of confusion existed as to whether the aircraft had been involved in a dog baiting operation. When interviewed the employee was extremely vague and stated that he was unable to remember anything from breakfast time that morning until after the accident.  He could not remember the reason for the flight, at what height the aircraft had been flying prior to the accident, or if he had been correctly seated. Later when interviewed by the police he stated that there had been no dog baiting gear in the aircraft, and that in the 11 months working at the property he had never seen dog baiting carried out.

When the pilot's wife advised the police of her concern at not being able to contact the aircraft, she told the constable that her husband and the employee had gone flying to check water conditions and conduct some dog baiting.  Later in a statement given to the police she said that the dog baits were kept in the hangar.

The aircraft wreckage was retrieved for further inspection.  Indications were that the aircraft had impacted the tree, then the ground at a relatively fast forward speed.  The cabin roof was crushed and the tail unit to cabin area failed between the luggage door opening and the right (passenger) door.  The luggage door, still attached to the cabin area, was undamaged indicating that it was probably open at the time of impact. If closed it would have offered a certain amount of structural integrity to that area of the fuselage and also sustain some degree of damage.

The aircraft appeared to be in good condition and regularly maintained.  A bulk strip and inspection of the engine showed that it was capable of normal operations, and the propeller damage indicated that the engine was under power at the time of impact.

The amount of fuel on board is unknown, but if the aircraft had suffered fuel exhaustion, or any other similar problem, the terrain was such that a survivable forced landing could have been made.

The Bureau of Meteorology advised that the general weather in the Maree to Birdsville area early that morning was fine with one octa of cloud at 5000 feet and light winds, but storms and heavy rain became evident during the day.

The emergency locator beacon (ELB) installed in the aircraft failed to activate at impact.  A new battery had been fitted recently, and the unit tested in the normal manner by turning on and listening for a signal.   Dismantling of the ELB revealed the impact switch to be faulty and was probably in this condition prior to the accident.

A postmortem carried out on the pilot revealed a 9% carbon monoxide level.  The pathologist believed this to be significant, and although not enough to cause the pilot to pass out, would have caused him some confusion.

Removal of the co-pilot and rear bench seat from the aircraft would have allowed the necessary space to carry a bag of dog baits and given the employee easy access to the luggage compartment door while seated on the floor.  It is therefore feasible that the luggage door was open as the means for the employee to drop these baits.  The location of the open door would have allowed exhaust gases to swirl back into the cabin, with the associated carbon monoxide effecting both pilot and passenger.

Inspection of the cabin heat and exhaust systems indicated that they had been serviceable prior to the accident and would not have contributed to carbon monoxide ingress to the cabin.  All door and window seals were intact and there was no evidence of any exhaust gas leakage past them.

Although it cannot be shown that the pilot was actually low flying and dog baiting, the evidence suggests that this type of operation had been carried out. The pilot did not have any formal low flying training, qualifications or approvals. There were no approved Flight Manual supplements, or other instructions issued allowing this aircraft to operate with doors opened or removed.

Safety Action

As a result of this occurrence, the following Safety Advisory Notice has been issued.

Safety Advisory Notice

The Bureau of Air Safety Investigation suggests that the Civil Aviation Authority:

1. Publish an article on the dangers of carbon monoxide ingestion from medical and operational perspectives, highlighting the dangers of flying with doors removed or open, particularly if such an operation is not approved in the aircraft flight manual; and

2. publish an article stressing the need for appropriate training and approvals to be obtained before undertaking low-flying operations.

   In light of this occurrence, it is suggested that the article could incorporate both topics.

Factual information

The glider was launched by aerotow for a local flight and at about 2,000 ft it was observed by the tug pilot to release and to fly straight and level.

Sometime later, the pilot a of glider flying in the Waikerie circuit area reported that there was a damaged glider in a field about 3 km south of the airfield. The tug pilot immediately commenced an aerial search and on locating the severely damaged glider, alerted emergency services. The pilot had not survived the impact.

On-site examination of the wreckage indicated that the glider had impacted the flat, grass covered terrain at high speed in a vertical, or near vertical dive. There was no evidence that the aircraft had been rotating immediately at impact and all aircraft components were located at the site except for the radio battery. Impact forces had destroyed the cockpit area, partially detached both wings, and broken the fuselage near the wing trailing edge.

The wreckage was recovered to a hangar at the airfield and inspected by engineers. Despite the extreme disruption of the airframe, all primary control system components were identified and examined. Many components had fractured during impact, however, it was determined that the control systems were all correctly connected prior to impact. The damage to componentry precluded a conclusive examination for jamming or obstruction of the control systems. The radio battery location was in an area of the aircraft well away from the control systems. The battery to electrical system connector wiring was found torn apart, consistent with separation of the battery from the aircraft at impact.

The glider had a valid maintenance release, and no maintenance deficiencies were identified. No evidence was found to suggest that a pre-existing failure of an aircraft component contributed to the accident.

The pilot was one of a group of foreign glider pilots visiting Waikerie for a period of intensive flying. He was correctly licensed and endorsed on the type. Prior to being approved to conduct solo flights at Waikerie, he was given flight instruction which included stall and spin recovery techniques.

A witness reported that on the day before the accident, a similar glider flown by the same pilot had pitched steeply nose-down and lost height immediately after release from the aero-tow.  The pilot was severely shaken, and he was subsequently debriefed by instructional staff before undertaking further flying.

The tow had appeared normal to the tug pilot who also briefly observed the glider in straight and level flight following the release. The descent was apparently not observed; however, in the light of the witness report of the previous day's incident, the possibility that the pilot lost control of the glider cannot be discounted.

The reason for the dive and the inability of the pilot to regain control of the glider could not be determined.

The pilot was having a dam constructed on his property which is adjacent to the Oakey airfield. Witnesses working on the dam site reported that the pilot had indicated that he would conduct a low fly-past over the dam after taking off from Oakey.

The aircraft was observed to fly at low level across the dam and commence a climb before striking powerlines located on the property. After the mainwheels contacted the wires, the aircraft impacted the ground inverted. The pilot received fatal injuries.

After an uneventful flight from Merimbula, the pilot overflew the airstrip to check the windsock. He noted that the windsock was swinging erratically around a mean direction of about 30 degrees left of the strip direction (approximately 140 degrees magnetic). The pilot then positioned the aircraft on the downwind leg to land towards the south-east.

Neither the pilot nor the surviving passengers reported any significant turbulence during the circuit. The pilot indicated that he was aiming to touch down about 100m in from the end of the strip. At what he thought was about 100 feet above the level of the strip, at an indicated airspeed of 85-90 kt, and with full flap selected, the aircraft rapidly lost altitude and landed very heavily a short distance in from the end of the strip. It then bounced, becoming airborne again.

The pilot reported that he was startled by the heavy landing. When the aircraft became airborne again, he momentarily applied power to go around but saw that the aircraft was headed towards trees, so he closed the throttle. His memory from this point was not complete but he did recall applying full right rudder, with no apparent effect, as the aircraft headed towards the trees. He also recalled the stall warning operating twice - once during the sink which led to the heavy landing, and again when the aircraft bounced.

Examination of the scene of the accident revealed that after the aircraft bounced, it contacted the ground again, left wing tip first, about 150m beyond the initial impact point and heading towards the left side of the strip. By this stage, the aircraft had developed a marked right skid. It continued in this manner across a dirt mound at the left edge of the strip and struck trees. The principal impact occurred when the aircraft fuselage just forward of the right-wing root struck a large tree, causing severe deformation to the right-side cockpit area.

The aircraft was equipped with an autopilot and a yaw damper. The pilot had conducted the cruise section of the flight with both these aids engaged. On arriving overhead, the strip he had disengaged the autopilot via the control wheel disengage switch. In normal operations, this switch also disengages the yaw damper. On this occasion, the pilot had checked that the autopilot had disengaged but did not confirm the yaw damper had disengaged. The pilot expressed the view that the difficulty he experienced in attempting to regain directional control when the aircraft was heading towards the left side of the strip could have been due to a problem with the yaw damper. However, a check of the yaw damper system after the accident did not reveal any faults.

The surface wind at the time of the accident was estimated by the Bureau of Meteorology to have been 110/15 knots.

The sequence of events described by the pilot indicates that the aircraft probably encountered windshear or a downdraft on late final approach. Given the prevailing wind conditions and the local topography, either of these phenomena could have been present. The pilot's recollection that he heard the stall warning sound during the bounce, plus the fact that the aircraft then contacted the ground left wing tip first indicate that the aircraft probably stalled during the bounce (possibly as a result of the pilot closing the throttle), causing the left wing to drop. The effect of the left wing tip dragging on the strip surface would have been to yaw the aircraft further (i.e. exacerbate the right skid). The decreasing speed of the aircraft as it headed towards the edge of the strip, along with the large skid angle, would have reduced rudder authority. This would then have prevented the pilot regaining directional control of the aircraft.

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

1. Windshear or downdraft conditions caused the pilot to lose control of the aircraft on late final approach.

2. The aircraft probably stalled during the bounce after a heavy landing, causing the left wing to contact the runway and the aircraft to yaw further left.

3. A severe right skid and decreasing speed reduced rudder effectiveness and prevented the pilot from regaining directional control.

The aircraft arrived at Snowy Range airstrip from Moorabbin at 1245 ESuT to participate in fire-bombing operations. Three fire-bombing flights to Mt Murray were completed. The aircraft was then reloaded and refuelled prior to the next flight which departed Snowy Range at 1455. At 1515, the pilot of a spotter aircraft, participating in the firefighting operation at Mt Murray, reported that VH-WEK had crashed while completing a fire-bombing run.

There were numerous firefighters who witnessed VH-WEK make its bombing run, some also witnessing the accident. A media helicopter crew recorded on video the aircraft making its bombing run and the accident sequence. From these sources, it was established that the aircraft made its bombing run flying up a steep slope on Mt Murray. The retardant was dropped and, about four to five seconds later, the aircraft appeared to commence a left turn. It was apparent from the video that airspeed was rapidly decreasing at this time. The aircraft appeared to stall, after which it struck trees and crashed.

Immediately after the accident, the helicopter pilot flew his aircraft to about 100 feet above the trees in the vicinity of the accident site but reported that due to downdrafts he was unable to sustain slow speed flight. He then repositioned his aircraft to about 500 to 600 feet above the accident site where he was able to sustain slow speed flight.

Witnesses reported that the engine of VH-WEK was at high power until the time the aircraft hit the trees. The previous bombing run was also made up-slope and the aircraft recovered via a wingover manoeuvre. Witnesses estimated that the aircraft was higher above the trees on the first run than it was on the accident run.

The investigation did not disclose any aircraft defect that could have contributed to the accident. The pilot probably elected to fly up-slope for greater bombing accuracy. However, up-slope runs create a difficult situation for exiting the valley at the completion of the run. An up-slope run also limits the options available in the event of an encounter with a downdraft, an adverse wind shift or a mechanical malfunction that prevents the load being dropped. The reason for the apparent loss of airspeed as the aircraft completed the firebombing run may be attributable to the reported downdrafts. However, this could not be positively determined.

Factors

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

1. The pilot flew the fire-bombing run up a steep slope.
2. After the load was dropped, there was a loss of airspeed to the extent that a recovery after completion of the bombing run was not possible.
3. Downdrafts were evident at the time of the accident.