Loss of control

Britten Norman Ltd BN-2A-26, VH-XFF

Safety Action

As a result of this occurrence, the Australian Transport Safety Bureau (formerly BASI) is investigating a possible safety deficiency 19990038 that relates to the security of airfields in the Torres Strait against public access.

Any safety output issued as a result of the analysis of safety deficiency 19990038 will be published in the Bureau's Quarterly Safety Deficiency Report.

Significant Factors

The pilot initiated a go-around from final approach because of a vehicle on the airstrip.
The left propeller showed little evidence of rotation damage. The reason for a possible loss of left engine power could not be determined.
For reasons that could not be established, the pilot lost control of the aircraft at a low height.

Analysis

The flight

The flight apparently proceeded normally until late final approach when the pilot initiated a go-around because of a vehicle on the airstrip. There were clear indications from the wreckage examination that the aircraft was rolling and yawing left at impact. The status of the left engine at impact logically supported such aircraft behaviour. While the witness description of the aircraft initially veering left also supported this conclusion, the report that the aircraft rolled right immediately before impact did not. In the asymmetric power and low speed situation that existed, it was most unlikely that the aircraft could have rolled right. On balance, therefore, the direction of roll as recalled by the witnesses was incorrect.

Whether the vehicle entered the airstrip during the latter stage of the aircraft's approach, or whether it was on the airstrip and the pilot expected it to move, was not determined. However, the position of the wing flaps at impact suggested that the pilot had selected full flap, and that the flaps subsequently did not move from this position. This implied that the pilot had been committed to land and that the aircraft speed was at, or less than, 65 kts.

Under normal circumstances, a go-around with both engines operating would have been a relatively basic procedure for the pilot to conduct. Because there was no apparent earlier action or radio call, it is unlikely that the pilot was aware of an asymmetric engine condition until the go-around was initiated. When the asymmetric power condition arose, the pilot's task was complicated by a number of aspects:

the aircraft was at low level, and probably low speed, when the go-around was initiated. This would have provided minimal opportunity for the pilot to lower the nose of the aircraft to increase airspeed and hence aircraft controllability;
depending on the exact position of the aircraft when the go-around was initiated, the pilot may have had to manoeuvre away from the sand dune and coconut palms on the southern side of the strip;
the pilot had to deal with the control forces associated with the asymmetric power condition, in addition to those associated with the engine power increase;
to retract the flaps to the take-off position, feather the left propeller, and adjust the elevator and rudder trims would have required the pilot to fly the aircraft with her left hand while conducting these other tasks with her right hand. Completion of these tasks may have been difficult, if not impossible, in that control of the aircraft may have required the pilot to use two hands on the control yoke to overcome the out-of-trim forces;
the pilot's stature, seating position as altered by the cushions she normally used, and the position to which the rudder pedals had been adjusted, may have affected her ability to manipulate the aircraft controls to the extent necessary to maintain control of the aircraft;
at a speed of 60 kts, the aircraft would have taken about 7 seconds to travel from overhead the witnesses at the eastern end of the island direct to the impact position. While the actual aircraft track was not established, this timeframe was probably indicative of the period available for the pilot to recognise the situation, evaluate available options, decide what action should be taken, and initiate that action; and
the north-westerly wind would have exacerbated any tendency for the aircraft to drift left as a result of the asymmetric power situation.

These influences would have placed the pilot under an extreme combination of workload and stress and may have affected her decision-making and flying ability.

An alternative course of action available to the pilot was to overfly the vehicle and land the aircraft on the remaining section of strip. Another was to reduce power on the right engine and conduct an emergency landing on the tidal flat area. However, without accurate information concerning the position and altitude of the aircraft when the go-around was initiated, no positive conclusions could be drawn concerning these options.

Wreckage examination

The pre-impact position of the carburettor heat controls for both engines could not be positively determined. It is possible for ice to have formed in one carburettor and not the other. If ice was present in the left engine carburettor during the approach, it was unlikely to have been evident to the pilot because the engine was probably operating at low power. Such a condition could have caused the engine to fail to respond at the commencement of the go-around. Because of the saltwater corrosion damage, it was not possible to assess the pre-accident condition of the carburettor. It is also possible that aggressive throttle operation by the pilot at the commencement of the go-around could have affected normal engine operation. In summary, there was insufficient evidence to reach a positive conclusion concerning the operation of the left engine.

Examination of the aircraft wreckage did not reveal any evidence to link the circumstances of the accident with the defects listed in ASR 111642, or those subsequently rectified on 2 January 1999. Further, no evidence was found of any aircraft unserviceability being reported and/or recorded between 2 January and the accident flight.

Factual Information

History of the flight

Uzu Air conducted passenger and freight operations between Horn Island and the island communities in the Torres Strait. It operated single-engine Cessna models 206 and 208 aircraft, and twin-engine Britten Norman Islander aircraft.

On the morning of the accident, the pilot flew a company Cessna 206 aircraft from Horn Island to Yam, Coconut, and Badu Islands, and then returned to Horn Island. The total flight time was about 93 minutes.

The pilot's schedule during the afternoon was to fly from Horn Island to Coconut, Yam, York, and Coconut Islands and then back to Horn Island, departing at 1330 eastern standard time. The flight was to be conducted in Islander, VH-XFF. Three passengers and about 130 kg freight were to be carried on the Horn Island - Coconut Island sector. Another company pilot had completed three flights in XFF earlier in the day for a total of 1.9 hours. He reported that the aircraft operated normally.

Witnesses at Horn Island reported that the preparation for the flight, and the subsequent departure of the aircraft at 1350, proceeded normally. The pilot of another company aircraft heard the pilot of XFF report 15 NM SW of Coconut Island at 3,500 ft. A few minutes later, the pilot reported downwind for runway 27 at Coconut Island. Both transmissions sounded normal.

Three members of the Coconut Island community reported that, at about 1410, they were on the beach at the eastern extremity of the island, about 250 m from the runway threshold and close to the extended runway centreline. Their recollections of the progress of the aircraft in the Coconut Island circuit are as follows: the aircraft joined the downwind leg and flew a left circuit for runway 27; the aircraft appeared to fly a normal approach until it passed over their position at an altitude of 200-300 ft; and it then veered left and commenced a shallow climb before suddenly rolling right and descending steeply onto a tidal flat, about 30 m seaward from the high-water mark, and about 200 m from their position.

Injuries to persons

Injuries	Fatal	Serious	Minor	None	Total
Crew	1	-	-	-	1
Passenger	2	1	-	-	3
Ground	-	-	-	-	-
Total	3	1	-	-	4

Damage to aircraft

Severe disruption to the outer right wing and nose sections occurred as a result of impact forces. Less significant damage occurred to the outer left wing leading edge. The fuselage fractured just aft of the wing trailing edge. The wing attachment points failed, allowing the wing to rotate forward and partially crush the cockpit/forward cabin area. There was a compression fracture of the upper surface of the left horizontal stabiliser near the inboard end. The outboard end of the left stabiliser had been bent upwards by ground impact.

Other damage

There was no other damage.

Personnel

Pilot

Age: 27
Licence category: Commercial
Medical certificate: Class 1 (valid to 27 June 1999)
Instrument rating: Command Multi Engine
Total flying hours: 2,540
Total on type: 197
Total last 90 days: 205
Total last 24 hours: 2
Last flight check: 12 November 1998

Flying experience and qualifications
The pilot began flying in 1990 and gained a Private Pilot (Aeroplane) Licence on 21 March 1991. She was issued with a Commercial Pilot Licence on 18 August 1994 and gained a Command Multi-engine Instrument Rating on 21 October 1996. On 1 February 1995, the pilot qualified as a Grade 3 Fixed Wing flying instructor, and gained a Grade 1 instructor rating on 25 September 1997. She was issued with a multi-engine training approval on 30 March 1998.
As well as being qualified to fly Islander aircraft, the pilot held endorsements on a number of other twin-engine aircraft, including Aero Commander, Beechcraft Baron, Cessna 310, Piper's Navajo, Seneca, and Seminole.
The pilot completed her endorsement on the Islander on 10 September 1998 and a proficiency check on 16 September 1998. The endorsement and check reports indicated that the pilot operated the aircraft at a high standard, and was disciplined and thorough with checks and procedures. No significant deficiencies were recorded. The training included asymmetric handling sequences, one of which was a simulated single-engine go-around from final approach with the wing flaps at the take-off position.
The pilot completed airfield checks at a number of airstrips in the Torres Strait, including Coconut Island, on 12 November 1998.
Seven-day history
The following summary of the pilot's flight and duty times was taken from company records:
Date Duty hours Flight time (hours)
9 January 0630-1800 4.1
10 January day off nil
11 January 1200-1800 nil
12 January 0700-1800 4.8
13 January reserve nil
14 January 0700-1830 7.3
15 January day off nil
Associates of the pilot reported that she appeared in good health on the morning of the accident.
Seat cushions
The pilot was approximately 157 cm tall. The operator reported that the pilot used two foam-rubber cushions (one on the seat and the other against the seat back) to adjust her seating position to enable her to achieve full movement of the cockpit controls. The seat cushions normally used by the pilot were not found. No person was found who could recall the pilot taking the cushions to the aircraft before the flight. However, the cushions were not at the company office where they were usually stored when not in use. Assuming they were on the aircraft, it is likely that they were lost as a result of the post-accident tidal and/or wind action.

Age:	27
Licence category:	Commercial
Medical certificate:	Class 1 (valid to 27 June 1999)
Instrument rating:	Command Multi Engine
Total flying hours:	2,540
Total on type:	197
Total last 90 days:	205
Total last 24 hours:	2
Last flight check:	12 November 1998

Date	Duty hours	Flight time (hours)
9 January	0630-1800	4.1
10 January	day off	nil
11 January	1200-1800	nil
12 January	0700-1800	4.8
13 January	reserve	nil
14 January	0700-1830	7.3
15 January	day off	nil

Aircraft information

Significant particulars

Registration: VH-XFF
Manufacturer: Britten Norman Pty Ltd
Model: BN2A-26 Islander
Serial number: C763
Country of manufacture: United Kingdom
Engines: Lycoming O-540-E4C5
Certificate of airworthiness

Number: CS/34
Issued: 18 December 1989
Category of operation: Normal
Certificate of registration

Holder: Uzu Air Pty Ltd
Number: CNS/00034/04
Issued: 6 January 1994
Maintenance release

Number: 285070
Issued: 5 December 1998
Valid to: 5 December 1999
Total airframe hours: 16,775.3 hrs
Weight and balance
The aircraft weight at the time of the occurrence was about 2,759 kg. The maximum allowable take-off weight was 2,994 kg. The centre of gravity was within limits.
Maintenance history
An examination of the maintenance history of XFF revealed that the aircraft had been inspected on 6 November 1998 by an airworthiness officer from the Civil Aviation Safety Authority. As a result of the inspection, Aircraft Survey Report (ASR)111642 was issued to the maintenance organisation. The report listed five Code B and one Code C defects. Persuant to Civil Aviation Regulation 38(1) the maintenance organisation was required to assess and rectify Code B defects as necessary. CASA form ASSP 604 states that "An endorsement of the maintenance release in accordance with Civil Aviation Regulation 50 may be required". Yes and no boxes, on the Aircraft Survey Report (ASR)111642 dated 6 November 1998, to indicate whether maintenance release endorsement was required, were not entered. Code C defects constitute "a contravention of requirements imposed under the Civil Aviation Regulations" and were required to be assessed and rectified as necessary.
The defects were:
an oil leak in the left engine - Code B;
the left landing gear torque links were worn at the pivot points - Code B;
cracks in the left landing gear cowling - Code B;
surface corrosion on the underside of the left wingtip - Code B;
a broken bonding wire on the right flap - Code B; and
there was no load limitation placard on the rear baggage door - Code C.
The aircraft logbook recorded that the last Schedule 5 (100 hourly) maintenance on the aircraft was completed on 5 December 1998. There was no record that the defects notified in ASR 111642 had been rectified during the maintenance. The engineering manager had certified an entry in the logbook regarding the inspection. It stated that there were no defects noted during the maintenance. The aircraft was flown the following day.
An entry in the aircraft logbook dated 02 January 1999 listed the following maintenance actions:
An oil leak from the left engine was rectified by the removal of the engine sump, replacement of the sump gasket and re-fitment of the sump assembly.
Surface corrosion on the left-wing tip was repaired.
Stop drilling was conducted to control cracks in the left main landing gear leg fairing.
A left engine cowl latch was replaced.
Both left and right magnetos on the left engine were replaced with overhauled units. This was done for convenience as the replaced units were approaching the end of their in-service lives.
The left engine lower mounts were replaced.
The engine dual tachometer (RPM) instrument was repaired and refitted to the aircraft.
Support brackets were fitted to the left engine exhaust.
Bonding wire on the right-hand flap was replaced.
The right engine starter was lubricated.
Engine intake ducting to the left engine was replaced because of oil contamination.
There was no record of any maintenance being conducted on the left landing gear torque links.
At the time the maintenance was carried out, the aircraft had completed 19.6 flying hours since the issue of the maintenance release on 5 December 1998. The aircraft then completed a further 43.9 flying hours before the commencement of the accident flight. There was no record of any maintenance action being undertaken during this intervening period relating the rectification actions or any other matter.

Registration:	VH-XFF
Manufacturer:	Britten Norman Pty Ltd
Model:	BN2A-26 Islander
Serial number:	C763
Country of manufacture:	United Kingdom
Engines:	Lycoming O-540-E4C5

Number:	CS/34
Issued:	18 December 1989
Category of operation:	Normal

Holder:	Uzu Air Pty Ltd
Number:	CNS/00034/04
Issued:	6 January 1994

Number:	285070
Issued:	5 December 1998
Valid to:	5 December 1999
Total airframe hours:	16,775.3 hrs

Meteorological information

The Bureau of Meteorology advised that the probable weather at Coconut Island around the time of the accident was as follows:

Isolated to scattered showers, and isolated thunderstorms;
North-westerly wind at about 15 kts;
Generally good visibility but reducing in precipitation; and
Broken cumulus cloud with a base at 2,000 ft, with broken higher layers.

At 1400, the automatic weather station at Coconut Island recorded an ambient temperature of 30 degrees Celsius, a dew point of 25 degrees Celsius, and an atmospheric pressure of 1007 hectopascals. Witnesses at the island reported that the weather was fine at the time of the accident, with the wind gusting from the northwest.

Aids to navigation

Not relevant

Communications

The pilot was communicating on the area frequency of 120.3 MHz during the flight. The pilot of another aircraft heard transmissions from the pilot of the Islander on that frequency.

Aerodrome information

Coconut Island is about 110 km NE of Thursday Island. The island is composed of coral sand and is predominantly flat. It extends east-west for about 1.75 km, and is less than 0.5 km across, north-south, at its widest part. The airstrip occupies the eastern portion of the island and is aligned east-west. It is 880 m long, 60 m wide and composed of grassed coral sand. On the southern side of the strip, and extending for most of its length, is a sand dune approximately 5 m high with coconut palms growing on it.

The threshold for runway 27 is about 350 m from the eastern extremity of the island. At the time of the accident, the local refuse tip was situated between the end of the strip and the eastern extremity of the island, and north of the extended centreline of the runway. A dirt road linked the community living area and the refuse tip. The road followed the southern side of the strip to the eastern end before turning north towards the refuse tip area.

Flight recorders

The aircraft was not equipped with flight data or cockpit voice recorders, nor was such equipment required by regulation.

Wreckage examination

The wreckage was subjected to tidal saltwater immersion for 3 days before it was examined.

Airframe
An examination of the airframe did not reveal any fault that might have contributed to the accident. All flying controls were capable of normal operation prior to impact. The wing flaps were in the full-down position at impact. The right-wing fuel tank had been ruptured by the impact, while the left-wing tank was intact. A significant quantity of fuel remained in the left tank.
Cabin
The pilot's seat was mounted on a frame attached to the cabin floor. The seat could be adjusted fore and aft on the frame, but there was no vertical adjustment. During the impact, the frame partially collapsed down and towards the right. The seat was locked in the full-forward position. The pilot's lap-sash harness assembly remained intact during the impact.
The rudder pedals were adjustable fore-aft into a locked position as selected by the pilot. The rudder pedals on the left side of the cockpit were locked one notch forward of the rearmost position. Damage indicated that the pedals were locked in that position at impact.
The cabin was fitted with four bench-type passenger seats, each capable of seating two persons. The seat frames were secured to the floor. Two lap safety harnesses were attached to each seat frame.
At the initial examination of the wreckage, there were no passenger seats in the cabin. All seats had been removed from the cabin during the rescue activities. One seat, found above the high-water mark, was recovered for examination. The remaining seats were not found and probably disappeared as a result of tidal action.
Those involved in the initial response following the accident indicated that one seat remained attached to the cabin floor and was levered free with a crowbar. The remaining seats were loose, apparently after becoming detached during the impact sequence. Examination of the seat attachment points indicated that the first, second and third row seat frames had failed due to impact induced stresses. There was significant bending forward and to the right. Examination of the seat found above the high-water mark indicated that it was the rear seat that had been levered from the floor during the rescue activities.
Apart from the two safety harnesses attached to the rear seat, only one-half of one other passenger harness was recovered. A section of a broken seat attachment bracket remained attached to the harness. The original location of the harness piece could not be determined.
Engines and propellers
Both engines and propellers were recovered from the accident site and examined. Disruption of the airframe prevented determination of the position of the engine controls at impact.
The right propeller exhibited signs of severe tip curl and leading-edge abrasion, consistent with the engine developing high power at impact. Examination of the engine did not reveal any condition likely to have prevented normal engine operation. Salt-water corrosion damage prevented a detailed examination of the carburettor.
The left propeller showed little evidence of rotational damage. The propeller had not been feathered. Laboratory examination of a failure of the left engine mixture control rod confirmed that the failure occurred at impact as a result of impact induced stresses. Examination of the engine did not reveal any condition likely to have prevented normal operation. After sand and other internal debris were removed, the magnetos were bench run for more than 30 minutes. They functioned normally during that period. The condition of the carburettor prevented confirmation of its serviceability at impact.
Carburettor heat system
The left and right carburettor heat control levers were mounted on the lower quadrant of the cockpit centre pedestal. Both levers had been bent flat against the pedestal face, and were in the OFF position.
The carburettor air intake system of each engine had been destroyed during the impact sequence. Neither the pre-impact position of the normal/alternate air doors, nor the condition of the hot air flexible hose, could be determined.

Impact information

Consideration of the wing and nose section crush lines, along with the nature of damage to the fuselage and horizontal stabiliser, indicated that the aircraft was yawing and rolling left at impact. The pitch attitude at impact was 40-50 degrees nose-down. The right wing struck the ground first and bore the principal impact. The nose section, and then the left wing outboard leading edge struck the ground. Because of tidal activity, no ground impact marks were evident. The aircraft speed at impact could not be determined.

Medical and pathological information

The Bureau had not received the medical and pathological information at the time of the release of this report.

Fire

There was no fire.

Survival aspects

The deformation of the nose section and the forward/downward rotation of the wing significantly reduced the occupiable cockpit space. This, along with the impact forces, meant that the chances of survival for the pilot were low.

The surviving passenger indicated that she occupied the seat row immediately behind the pilot. The other two passengers occupied the second and third rows. The failure of the seat-to-floor attachments of the occupied seats in the aircraft cabin indicated that deceleration forces experienced in this area were high, thereby reducing survivability.

Aircraft operation

Emergency operating procedures
Section 4 of the Owner's Handbook for the aircraft type addresses emergency operating procedures. Relevant extracts from the section include the following:
"Warning ...
It is essential to raise the flaps to the fully up position to achieve the optimum climb gradient."
"Critical engine
Failure of the left engine has the most adverse effect on the handling and performance of the aircraft."
"Landing with one engine inoperative
Make an initial approach to approximately 65 kt (75 m.p.h.) IAS with the flaps selected to TAKE-OFF (25 deg). When committed for landing, select FLAPS DOWN (56 deg) and reduce speed over the threshold to a value compatible with the information scheduled in Sect. 6 and touchdown normally."
Section 3, Operating Instructions, of the Owner's Handbook, included the following information:
"Touch down
Initial approach should be made at 65 kts (75 m.p.h.) IAS with flaps at TAKE-OFF (25 deg). After selection of FLAPS DOWN (56 deg) the speed may be progressively reduced to the appropriate threshold speed quoted in Section 6. After touch down allow the nose wheel to sink gently and apply the brakes as required."
"Baulked landing
Apply full power smoothly to the engines and be prepared to deal with a nose-up change in trim which can require a strong stick force, especially if the airspeed is low. Establish a positive climb away, select flaps to T.O., trim the aeroplane and accelerate to 61 kts (70 m.p.h.). Select flaps UP at a height above 200 feet and climb out at 65 kts (75 m.p.h.) IAS."
Carburettor icing
Section 3, Operating Instructions, of the Owner's Handbook, included the following information:
"260 H.P. ISLANDER
Use of carburettor heat
Carburettor icing can occur, unexpectedly, in various combinations of atmospheric conditions. On damp, cloudy or foggy days, regardless of the outside temperature, keep a sharp watch for power loss, indicated by a decrease in manifold pressure. When this is seen, apply full carburettor heat for 30 seconds; this action will cause a further slight drop in manifold pressure. Return the heat control levers to OFF and note that selected engine power is restored. Do not keep heat selected FULL for long periods or excessive power loss will result, with very little indication from the manifold pressure indicator. During normal flight operations the carburettor heat control levers should be left in the OFF position."
Section 3 also included, in the "Airfield Approach" checklist, the following comment on carburettor heat:
"Intermittent use may be advisable to ensure responsive engines if a baulked landing is likely and ambient conditions are such that ice formation could occur."
The temperature information supplied by the Bureau of Meteorology for Coconut Island around the time of the accident indicated that the atmospheric conditions were conducive to light carburettor ice forming at cruise or descent engine power settings.
The company chief pilot knew of no instance of carburettor icing in Islander aircraft operating in the Torres Strait. The normal practice was that company pilots did not use carburettor heat during flights in the area. Similar comment was received from other organisations and pilots with extensive experience in operating Islander aircraft in the Torres Strait area.
Aircraft wing flap operation
The Owner's Handbook, Section 2, titled Design Information, under the sub-heading Flight Controls, contained the following information:
"Electrically operated single-slotted flaps are fitted. An actuator on the wing rear spar operates the flaps through a system of push-pull rods. A selector switch on the pilot's console controls the actuator and a flap position indicator is situated on the cabin roof instrument panel. The flap control selector switch is a spring-loaded centre OFF unit and is wired to the actuator through a system of relays. Moving the switch to the DOWN position will only move the flaps 25 degrees to a TAKE-OFF setting and when this setting has been reached a second downward switch movement will be required to set the flaps to DOWN. Similarly, when raising the flaps, the first switch movement will only raise them to the TAKE-OFF setting and a second switch movement is necessary to completely raise the flaps."
Pilots who had flown the aircraft indicated that the flap selector switch had to be held up or down against the spring, for a short time, before flap movement commenced.

Aircraft single-engine climb performance

Section 1 of the Owner's Handbook for the aircraft stated that the minimum control speed (single engine) was 39 kts. It applied when the flaps were up and the propeller on the inoperative engine was feathered.

Section 6 of the Owner's Handbook contained aircraft performance data, including single engine rate of climb data at 65 kts with the flaps up. The data indicated that, at an aircraft weight of 2,727 kg, an ambient temperature of 30 degrees Celsius, and at sea level, the rate of climb the aircraft was capable of achieving with one engine inoperative was about 160 ft/min.

The aircraft manufacturer advised that there were no actual performance figures available for the BN-2A-26 Islander aircraft with one engine inoperative, propeller unfeathered, and flaps down. However, there were unofficial climb figures for a BN-2B-26 variant of the Islander, with flaps up, and an unfeathered propeller. These were measured under test conditions at 65 kts airspeed and indicated that there was a decrement of between 70 and 90 ft/min (depending on the unfeathered propeller RPM) below the scheduled one-engine inoperative performance figures. The manufacturer also advised that aircraft performance with both engines operating was reduced by approximately 40 per cent when the flaps were selected from up to down, although this data could not be applied directly to flight with one engine inoperative. Go-around tests with one engine inoperative and flaps down had not been conducted.

Pilots experienced on the aircraft type, reported that the performance of the aircraft with flaps down and one propeller not feathered was unlikely to allow a successful go-around to be conducted.

Other information

Information from surviving passenger
Approximately 6 months after the accident, the surviving passenger provided the following information concerning the flight.
She was seated in the row behind the pilot.
One of the other passengers was in the second row, while the third passenger was in the third row.
Her safety harness remained secured throughout the flight.
There was no unusual event during the flight: the engines sounded normal.
When the aircraft was on approach to Coconut Island, the pilot said that they could not land because there was a truck on the airstrip.
The passenger saw a vehicle on the strip. It was stationary, and near the eastern end of the strip.
The pilot was cross and said that there was no driver in the vehicle.
Other information from witnesses at Coconut Island
At the time of the accident, an aircraft operated by another company was parked at the western end of the airstrip. Two pilots were loading a consignment of crayfish onto the aircraft. Neither saw or heard XFF arrive in the circuit or fly the approach, nor could they recall if a vehicle had been on the strip around the time the aircraft was on approach. They indicated that their loading activities, along with the existing wind conditions, would have greatly reduced the likelihood of them hearing sounds from the eastern end of the airstrip. They were not aware of the accident until one of the island residents who witnessed the accident from the eastern end of the island raised the alarm. They proceeded to the accident site and, along with some of the island residents, provided assistance to the victims as far as they were able. One of the island residents advised the Thursday Island Police of the accident. They arranged for a medical team and police to be flown to the island in two helicopters. They arrived at the island between one and one and one-half hours after the accident.
None of the three island residents who witnessed the accident reported seeing a vehicle on the airstrip when the aircraft was on final approach.
Information from other company pilots
Other pilots working for the operator indicated that island airstrips within the Torres Strait area were generally free of obstacles for their operations. There had been occasions, however, when vehicles, persons, or animals on the airstrip had caused pilots to go-around from a landing approach, requiring them to make a second approach.
There were no radio links between aircraft and persons at the island airstrips. Local populations relied on hearing and/or seeing aircraft arriving to become aware of their presence. Depending on the weather and wind conditions, pilots did not always overfly airstrips before joining the circuit but often joined the downwind leg before completing a base leg and landing off final approach.
Birdlife on the airstrip
In the period during which the accident occurred, there were large numbers of migratory birds on Coconut Island. Many hundreds were seen occupying the grassed runway area. The birds were small and difficult to see in the ankle-high grass. When approached by a vehicle, they generally remained on the ground until the vehicle was closer than 20-30 m. When they did fly, it was as a flock.
The opinion of company pilots was that the birds were not sufficiently large to constitute a significant safety hazard to aircraft operations. They believed that the pilot would not have discontinued the approach because of bird activity given their small size, and given that an aircraft would normally have been almost at the point of touchdown before the birds would begin to fly. However, there was no evidence that the aircraft had struck a bird.

Occurrence summary

Investigation number	199900220
Occurrence date	16/01/1999
Location	Coconut Island, (ALA)
State	Queensland
Report release date	16/12/1999
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Pilatus Britten-Norman Ltd
Model	BN2
Registration	VH-XFF
Serial number	763
Sector	Piston
Operation type	Charter
Departure point	Horn Island, QLD
Destination	Coconut Island, QLD
Damage	Destroyed

Saab SF-340A, VH-LPI

Summary

On 11 November 1998, VH-LPI, a Saab 340A turbo-propeller aircraft was enroute between Albury, NSW and Melbourne, Victoria on a scheduled public transport service. The aircraft was operating in instrument meteorological conditions and had accumulated a deposit of ice on the wings and windscreen wipers. The crew interpreted this ice deposit as being less than that required for them to activate the de-ice systems on the wing leading edges, in accordance with the aircraft flight manual procedures. As the aircraft approached Melbourne the crew were instructed to enter a holding pattern at Eildon Weir. The crew acknowledged this instruction and reduced power in order to slow the aircraft to the holding pattern airspeed. The crew subsequently allowed the airspeed to fall below the target speed of 154 knots, and despite remedial action, did not regain the target speed.

Shortly after the aircraft entered the holding pattern it suffered an aerodynamic stall and rolled approximately 126 degrees to the left and pitched nose down to approximately 35 degrees. The crew regained control after approximately 10 seconds. The aircraft lost 2,300 ft of altitude. The crew was not provided with a stall warning prior to the stall.

The investigation found that despite being certified to all required certification standards at the time, the Saab 340 aircraft can suffer from an aerodynamic stall whilst operating in icing conditions without the required warnings being provided to flight crew. This problem had been highlighted when the aircraft was introduced to operations in Canada and as a result a modified stall warning system was mandated for aircraft operated in Canada. This modification was not fitted to other Saab 340 aircraft worldwide.

The investigation also found a number of other occurrences involving Saab 340 aircraft where little or no stall warning had been provided to the crew while operating in icing conditions. Deficiencies were found in the operator's manuals, procedures and training.

During the course of the investigation, a number of recommendations were made in 1998 and 1999 concerning flight in icing conditions and modifications to the Saab 340 stall warning system. The completion of the investigation and finalisation of the report were the result of extensive consultation with the aircraft manufacturer and certification authorities.

Occurrence summary

Investigation number	199805068
Occurrence date	11/11/1998
Location	Eildon Weir
State	Victoria
Report release date	15/05/2001
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Incident
Highest injury level	Minor

Aircraft details

Manufacturer	Saab Aircraft Co.
Model	340
Registration	VH-LPI
Serial number	340A-151
Sector	Turboprop
Operation type	Air Transport Low Capacity
Departure point	Albury, NSW
Destination	Melbourne, VIC
Damage	Nil

Air Tractor AT-502, VH-SNA, near Rocky Gully, Western Australia, on 14 August 1998

Summary

The Air Tractor was being used to conduct aerial reconnaissance of a forestry area prior to spraying the trees. The north-easterly wind was gusting from about 15 kts and there was 8 OCTAS of low cloud with passing rain showers. The horizon was often obscured. The pilot reported that he encountered some turbulence during the flight.

On completion of the reconnaissance flight, the pilot decided to land towards the east-south-east. He reported that late in the landing approach, with full flap selected the aircraft unexpectedly rolled left. He was unable to correct the roll before the left landing gear struck the perimeter fence. The aircraft veered left, and its left wing struck the chemical loader that was parked near the edge of the airstrip. The aircraft then cartwheeled before coming to rest inverted. The pilot and bystanders were unhurt, but the aircraft was destroyed.

No deficiencies could be found with the aircraft that may have contributed to the accident.

Occurrence summary

Investigation number	199803258
Occurrence date	14/08/1998
Location	19 km E Rocky Gully
State	Western Australia
Report release date	04/08/1999
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	None

Aircraft details

Manufacturer	Air Tractor Inc
Model	AT502
Registration	VH-SNA
Sector	Turboprop
Operation type	Aerial Work
Departure point	Rocky Gully, WA
Destination	Rocky Gully, WA
Damage	Destroyed

Cessna A185E, VH-HTS

Summary

On Sunday, 26 July 1998, at about 1324 EST, a Cessna A185E floatplane, VH-HTS, crashed onto a ridge forming the southern shore of Calabash Bay NSW. The accident occurred during a go-around manoeuvre following an unsuccessful landing approach to the Berowra water alighting area. At the time of the accident the Calabash Bay area was affected by strong winds, widespread rain and showers, low cloud, and reduced visibility. The aircraft was operated by South Pacific Seaplanes and was undertaking a charter flight from Palm Beach to Berowra. All five occupants, including the pilot, suffered fatal injuries. The aircraft was destroyed by impact forces.

The investigation found that the circumstances of the accident were consistent with uncontrolled flight into terrain. The decision by the pilot to carry out a go-around into a confined area surrounded by steep-sided terrain was the culminating factor in a combination of local factors, organisational deficiencies and inadequate safety defences. Local factors included poor weather conditions, a lack of formal procedures to provide safe methods of operation, and commercial pressures. Organisational deficiencies were identified within South Pacific Seaplanes concerning the management and conduct of charter operations carried out by that company, and in the safety regulation of those operations by the Civil Aviation Safety Authority.

During the investigation a number of safety deficiencies were identified. Safety actions to address those deficiencies are currently being formulated by the Bureau of Air Safety Investigation. A description of those deficiencies, and corresponding safety actions, will be summarised in section 4 of the final report.

Occurrence summary

Investigation number	199802830
Occurrence date	26/07/1998
Location	Calabash Bay
State	New South Wales
Report release date	25/02/1999
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Cessna Aircraft Company
Model	185
Registration	VH-HTS
Serial number	18501835
Sector	Piston
Operation type	Charter
Departure point	Palm Beach, NSW
Destination	Berowra Waters, NSW
Damage	Nil

Bell 206B (III), VH-WCF, 204 km north-north-east of Geraldton, Western Australia

Summary

The helicopter was landed on an uneven 2 to 3 degree slope to offload two surveyors and their equipment. The forward sections of the skids were in firm contact with the ground, but because of the uneven surface the rear of the left skid was not in firm contact. After landing, the pilot lowered the collective and moved the cyclic control to confirm the helicopter was firmly seated on the ground before he allowed the passengers to disembark. The engine was running and the rotor was turning at 100% of operating RPM. There was a gusty 15-20 kt wind from 30 degrees to the right of the nose.

The rear seat passenger disembarked from the left (downhill) side, unloaded his equipment, and moved away from the helicopter towards the front as briefed. The front seat passenger disembarked from the left side, unloaded his equipment, climbed back on to the left skid, and reached into the cockpit through the door. The pilot said that he had been observing the site to his right to ensure it was clear, and when he looked back towards the front he realised the right skid was just off the ground. The pilot said he noticed a cool strong wind coming through his open window when the helicopter started to roll. He moved the cyclic control to the right but this had no effect. The pilot said he then pulled in collective but the helicopter continued to roll to the left and the left skid did not leave the ground. He then noticed the passenger on the top step on the left side. The pilot said he yelled at the passenger who immediately jumped off the step, closed the door and faced the helicopter with his arms outstretched. The helicopter continued to roll to the left and the passenger ran away directly to the left of the helicopter. As the weight came off the skids, the helicopter began to slide sideways down the slope. The slide was stopped, half a metre later by a partially buried stump and the helicopter rolled over. The pilot was unable to recover control before the rotor blades made contact with the passenger and the ground. The passenger was struck by at least one main rotor blade and was fatally injured.

It is probable that the helicopter very rapidly entered a condition known as dynamic rollover, where the only possible recovery action was to fully lower the collective. However, it is unlikely that the pilot had sufficient time to recognise the developing the situation and to take the appropriate action before the rollover became unrecoverable.

Occurrence summary

Investigation number	199703335
Occurrence date	12/10/1997
Location	204 km north-north-east of Geraldton
State	Western Australia
Report release date	25/02/1998
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Bell Helicopter Co
Model	206
Registration	VH-WCF
Serial number	3134
Sector	Helicopter
Operation type	Charter
Departure point	108 NM NNE Geraldton WA
Destination	110 NM NNE Geraldton WA
Damage	Substantial

Cessna U206F, VH-RPW, 25 km east-north-east of Canberra, Australian Capital Territory

Summary

Witnesses observed the aircraft at a height of approximately 200 ft soon after take-off from a local grass strip. The aircraft did not gain height and entered a steep nose-high attitude before apparently stalling. The aircraft then pitched down steeply and collided heavily with the ground. The aircraft was subsequently engulfed by fire. The pilot and two passengers sustained fatal injuries.

Occurrence summary

Investigation number	199603734
Occurrence date	15/11/1996
Location	25km ENE Canberra
State	Australian Capital Territory
Report release date	25/06/1997
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Cessna Aircraft Company
Model	206
Registration	VH-RPW
Serial number	U20602836
Sector	Piston
Operation type	Private
Departure point	Turalla, NSW
Destination	Coolah, NSW
Damage	Destroyed

Robinson R22 Beta, VH-EWQ, 194 km west-south-west of Windorah (ALA), Queensland

Summary

FACTUAL INFORMATION

History of the flight

The pilot had been tasked to ferry the helicopter from Windorah to Cadelga Station in preparation for cattle mustering. Several witnesses saw the helicopter depart at about 1620 EST. It was last seen some time after 1630 as it flew past South Galway Station, 61 km south-west of Windorah.

The track distance was 239 km with an expected flight time of about 1 hour and 40 minutes and an estimated time of arrival of 1800. The helicopter was expected at Cadelga Station before last light at 1829. When it had not arrived, the helicopter was reported missing. An extensive aerial search commenced at first light the next morning. The wreckage of the helicopter was found about 2 km to the right of the direct track and 31 km short of the destination.

Pilot information

The pilot was 20 years of age and had commenced his flying training on Bell 47 helicopters in March 1995. He gained an endorsement on Robinson R22 helicopters in May 1995. He passed his commercial helicopter licence test on 22 June 1995. In February 1996, the pilot passed a check flight with an instructor and obtained mustering training. Since then, he had been employed as a mustering pilot on a full-time basis.

The post-mortem examination report did not reveal any pre-existing physiological problems.

Wreckage examination

The helicopter wreckage was examined initially at the accident site and later transported to a maintenance facility at Archerfield Airport where a more detailed examination was possible. These examinations revealed that the helicopter had impacted in an attitude about 60 degrees nose-low and banked to the right. The skid gear had separated at impact and the remaining structure of the helicopter was severely compressed.

Significantly, the main rotor had ceased rotating, and the engine had stopped by the time the helicopter struck the ground. Sections of the tail boom were scattered to the right of the main wreckage. Heavy items, such as a jerry can full of oil and the tail rotor assembly, were strewn ahead, along track (approximately 245 degrees M). Lighter items, such as paint flakes and Perspex pieces, were scattered downwind, generally to the north of the main wreckage.

Examination of the main rotor blades found that both pitch-link rods were broken in overload and that both blades were bent into an "S" shape. The tail boom had suffered several main rotor blade strikes. The first blade struck on the flat with the top surface, distorting the tail boom and swinging the tail rotor assembly into the main rotor disc. The cabin was also struck by one or both main rotor blades.

The engine was bulk stripped at an engineering workshop. Nothing was found that would have prevented the normal operation of the engine. Examination of the exhaust manifold showed that the engine was still hot at impact. Both fuel tanks were holed, subsequently only a small quantity of clean fuel was recovered. The helicopter had undergone a periodic maintenance inspection prior to the flight.

Examination of the helicopter wreckage and of the maintenance documentation did not reveal any abnormalities which could have led to a loss of control.

Weather and environmental issues

An assessment of the weather conditions was obtained from the Bureau of Meteorology and local sources. The wind at 2,000 ft was a southerly at 10-15 kts. The surface wind was a light south-south-easterly, less than 5 kts. Cloud was scattered cumulus at 3,000-4,000 ft with patches of higher altocumulus. Sunset at the crash site was at 1808.

Robinson Helicopter Company research

Research undertaken by the Robinson Helicopter Company found that when the main rotor RPM decreases below 75% RPM, it will continue to decrease regardless of input from the pilot. In a short time span, the engine will stall, and the rotor system will stop completely. During flight with rotor RPM in the normal range, the blades are relatively straight due to centrifugal force. As rotor RPM decreases below the normal range, the main rotor blades bend upwards in a permanent set, the pitch link rods break in overload and the droop stop tusks also break or bend. The main rotor blades are then free to swivel at the mast and flail, striking the tail and cabin structure.

Cabin luggage

Any luggage has to be carried in the cabin of the helicopter: in the space under each seat, on the passenger's seat, or on the cabin floor in front of the passenger's seat.

The pilot carried three bulky items in the cabin: a swag (bedroll), a full 20-L jerry can, and a small overnight bag. The rolled-up swag was later measured at 1,060 mm long by 350 mm in diameter. It was held upright by the lap/sash seat belt on the passenger's seat. The location in the cabin of the 540 x 300 x 200mm overnight bag could not be determined. The jerry can containing engine oil was ejected from the helicopter, indicating that it was not restrained and probably lying on the cabin floor in front of the passenger's seat.

The swag and overnight bag were removed from the wreckage before the investigation team arrived on site. Therefore, any evidence of control interference caused by the luggage was lost. The Bureau's records show that since 1989 there have been four other similar occurrences, three of which resulted in accidents. In each occurrence, control was lost either totally or partially, due to inadequately restrained cargo in the cockpit. The 1989 accident was due to the in-flight movement of a swag and other equipment, held only by the passenger's seat belt.

Emergency locator transmitter

An emergency locator transmitter was not fitted to the helicopter, nor was one carried by the pilot.

ANALYSIS

Loss of control

The loss of main rotor RPM and engine stoppage was preceded by an event which resulted in loss of control. This event was sudden and severe enough to prevent the pilot from taking timely corrective action. An assessment of the helicopter's attitude at impact and the wreckage distribution indicated that this event occurred at an altitude in excess of 500 ft.

There was no physical evidence found to indicate that the swag shifted and interfered with the flight controls.

The event which led to a loss of control could not be identified.

SAFETY ACTION

Since 1989 there have been four similar occurrences, three of which resulted in accidents. In each occurrence, control was lost either totally or partially, due to inadequately restrained cargo in the cockpit.

The Bureau of Air Safety Investigation is considering an article for publication in Asia-Pacific AIR SAFETY highlighting the risks to safety from carriage of cargo in the cockpit of the Robinson R22 helicopter.

Occurrence summary

Investigation number	199601324
Occurrence date	25/04/1996
Location	194 km west-south-west of Windorah (ALA)
State	Queensland
Report release date	13/01/1997
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Robinson Helicopter Co
Model	R22 Beta
Registration	VH-EWQ
Serial number	1090
Sector	Helicopter
Operation type	General Aviation
Departure point	Windorah, QLD
Destination	Cadelga Station, SA
Damage	Destroyed

Centrum Naukowo-Produkcyjne-PZL PZL-104, VH-PZS

Safety Action

At a result of the investigation into this occurrence, the Bureau of Air Safety Investigation forwarded the following interim recommendation to the Civil Aviation Safety Authority on 4 November 1996:

IR960127

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

review the Aviation Safety Surveillance Program to ensure that new commercial operators are adequately monitored and inspected until a demonstrated history of safe operation is known;
align the scheduled surveillance period of the Aviation Safety Surveillance Program to that of the validity period of the air operators certificate;
reconsider the flight review requirements for Chief Pilots with the view of bringing them into line with the current situation for Chief Flying Instructors, as an additional method of surveillance;
review the adequacy of the approval and assessment requirements for Chief Pilots who do not have a demonstrated history in flight operations with a commercial operator;
review the current situation regarding Aeroplane Flight Reviews, to allow for appropriate notification to the Civil Aviation Safety Authority and recording of the results.'

Factual Information

Pilot information

The pilot's last aircrew medical examination was conducted on 18 May 1995. He held a valid Class 1 medical certificate. His commercial pilot licence was current and he was endorsed to fly tail-wheeled aircraft. His pilot's logbook and aircraft records showed that he had flown fewer than 70 hours in the preceding two years.

Records showed that the pilot had not undertaken an aeroplane flight review within the previous two years. His last documented aeroplane conversion training (which the Civil Aviation Safety Authority accepts as equivalent to an aeroplane flight review) was completed on 17 November 1993.

The instructor who conducted the conversion training said that the pilot's aircraft handling met the minimum required standard and that he had limited flying experience. The instructor advised the pilot to operate under an experienced chief pilot until he gained further flying experience. The pilot declined, saying that he wanted to run his own operation.

Within the preceding five months, several fellow pilots had on separate occasions observed the pilot flying his aircraft in an excessively steep climb after takeoff, followed by an early, low-speed turn. When they mentioned the implications of his conduct to him, the pilot responded by saying that the aircraft was designed for short takeoff and landing. He had been alone in the aircraft on these occasions. The impression given to people close to the pilot was that he regarded his aircraft as very stable and forgiving.

In early June 1995, the pilot was identified flying below 500 ft along the City Reach and the Toowong Reach of the Brisbane River in his distinctive aircraft. Neither the pilot's takeoff practice of climbing steeply, nor the low flying occurrence, was reported to the Civil Aviation Safety Authority.

The pilot worked from 0100 to 0500 EST as a cleaner at a supermarket. He had worked this shift schedule on at least four consecutive mornings the week of the accident, including the day of the accident. He had also flown a charter flight on the afternoon before the accident. On a typical work day, he normally slept after returning from work until about 0900, and again from about 2000/2100 until after midnight, then rose in time to go to work.

The postmortem examination report did not reveal any pre-existing physiological problems which could have affected the pilot's ability to fly the aircraft.

Air operator's certificate

On 16 February 1994, the Civil Aviation Authority (now the Civil Aviation Safety Authority) issued an air operator's certificate authorising the pilot to conduct charter and aerial work flights in his aircraft. When the certificate was issued, the Authority's policy was to inspect each operator once in every 12-month period. The inspection specified is limited to an examination of records, recording systems and facilities. The policy was changed in October 1995, requiring an inspection once in every 18-month period. An inspection of the pilot's operation had been scheduled for September 1995 but this was deferred indefinitely due to a high workload in the Authority's Archerfield office. In addition, the pilot had not been available for an inspection on an opportunity basis when the flying operations inspector's schedule permitted.

The inspection policy change, coupled with delays in scheduling, resulted in a lack of any periodic inspection of the pilot's operation. The flying operations inspector in charge of overseeing the operation said that, had he known of the pilot's potentially dangerous flying habits and the low-flying occurrence, he would have investigated. In addition, the Authority was unaware that the pilot's aeroplane flight review was not current. Legislation does not require notification that a review has taken place. The responsibility of keeping the aeroplane flight review valid rests with the pilot.

Aircraft information

The aircraft was manufactured in Poland and first registered in Australia on 1 November 1989. It was designed as a light utility aircraft for the short take-off and landing role. It was a fixed landing gear, tail-wheeled aircraft, equipped to carry a pilot plus three passengers. Available aviation literature and flight test reports highlighted the docile, power-off stall characteristics of the aircraft.

The aircraft's logbook showed that it had undergone a periodic maintenance inspection on 15 November 1995. The current maintenance release was invalid due to an omission by the licensed aircraft maintenance engineer. He had been unable to document the aircraft hours limitation as the pilot had not given him the expired maintenance release as proof of total hours flown. The new maintenance release was partially destroyed in the fire. As a result, the number of hours flown since the last periodic inspection could not be determined accurately, but was estimated to be in the order of 6 to 10.

No evidence was found in the maintenance records to suggest that the aircraft was not fully serviceable before the flight.

The managing director of the aviation firm which imported four PZL-104 had extensive experience flying the type. He said that the aerodynamic stall characteristics in level flight, power off, were very docile. Control could be regained by releasing the back pressure on the control stick. The aircraft stalled at about 38 knots with take-off flap selected. However, when the aircraft stalled in the take-off configuration with flap and full power, it rolled rapidly to the left, adopting a distinctly nose-low attitude. The altitude lost in the recovery was significant but would depend on how far the nose dropped below the horizon before the pilot reacted and regained control.

Wreckage examination

The wing structure was largely intact with only the centre section burnt. It was separated from the fuselage. The left wingtip struck the ground first and ground marks revealed that the aircraft was rotating left at impact. Take-off flap (21 degrees) was selected. The destruction pattern of the wooden propeller indicated that the engine was producing a significant amount of power at impact. Witnesses said that the engine noise did not seem to vary during the entire take-off /accident sequence. The engine was dismantled in an engineering workshop. Nothing was found which could have prevented normal engine operation.

The cabin area was destroyed by the impact and subsequent fuel-fed fire. All flight controls were checked and found to be free of pre-existing defects. Information received from the public initially cast doubt on the integrity of the pilot's seat/seat rail. Apparently, in several occurrences in Poland, the pilot's seat had been known to slide back on its rails, leaving the pilot unable to move the control stick far enough forward to regain control. Detailed examination of the seat-lock mechanism and rail found that the seat had not moved from the forward position.

Computations of the aircraft weight found that the maximum allowable take-off weight of 1,300 kg was exceeded by 40 kg. Due to the excess weight, the aircraft loading was outside the limits published in the centre-of-gravity graph.

Weather

A ridge of high pressure established along the coast, directing a moderate to fresh south-easterly airflow onto the coast and islands. The surface wind was estimated to have been a south-easterly at 10 knots. Winds at 500-1,000 ft were stronger at 15-20 kts. Witnesses at the airstrip commented that they noticed the occasional stronger gust of wind.

Aircraft performance

Evidence indicated that the pilot probably initiated a steep climb after take-off. With an excessively steep climb attitude, the aircraft's airspeed decreased rapidly, resulting in an aerodynamic stall, either at the top of climb or when the pilot rolled the aircraft into a left turn. Considering the aircraft's low altitude and the rapid attitude change in a power-on stall, the pilot would not have been able to regain control in time to avoid a collision with the ground. The pilot did not appear to detect or correct the potential problem arising from the aircraft performance in sufficient time to prevent the stall.

Contributing factors to the pilot's actions

Several factors appeared to contribute to the pilot's use of a steep climb attitude and his failure to detect or correct the potential problem in the aircraft's performance.

Firstly, the pilot appeared to believe that the aircraft was very stable and forgiving. This belief may have resulted in the pilot developing an undesirably low perception of the risk associated with some manoeuvres, particularly flying the aircraft with high rates of climb and low speeds after takeoff. After repeatedly flying this manoeuvre without adverse consequences it may have become part of his normal behaviour.

Secondly, the pilot had a relatively low level of overall flying experience, including recent flying experience. This meant that he was probably still encountering a significant workload during the take-off and climb phases. Consequently, he had only a limited amount of information processing capacity available to deal with the detection and resolution of a rapidly deteriorating situation. His low level of experience is also likely to have limited his familiarity with the nature of an impending stall.

One particular area in which the pilot appeared to have had limited understanding concerned the effect that different loads have on the aircraft's performance and capabilities. On the previous occasions in which the pilot was seen to have used a steep climb after takeoff followed by an early turn, there had been no passengers. The aircraft weight was therefore significantly below the maximum allowable take-off weight. However, on the accident flight, the aircraft weight was above the maximum allowable take-off weight. With a heavier than usual aircraft, the performance would not have been what the pilot normally experienced. In addition, the centre of gravity was further aft on the joy flight compared to a pilot-only flight, resulting in a lighter elevator control. The pilot's low level of experience may have meant that he was less able to associate a problem with aircraft performance to the heavier than normal operating weight.

Finally, the pilot was probably suffering from a significant level of fatigue at the time of the accident. Research has shown that working shifts during the critical hours between midnight and 0600 can lead to disruption of the human circadian rhythm. This disruption is due to physiological and environmental factors, as well as the social aspects of trying to sleep during the day when family matters and environmental noise may hamper sleep. Under these conditions the duration of sleep may be similar to that associated with a typical work schedule, but the quality of sleep obtained is usually less than optimal. A lack of quality sleep over a period of several days can be associated with a significant level of fatigue.

If the pilot was suffering from fatigue, many aspects of his performance may have been affected. The effects of fatigue may be exhibited in the form of slower reaction time, decrease in his perception and processing of incoming information, poor judgement, and inappropriate decision making. In other words a significant level of fatigue would probably have influenced the pilot's ability to detect and correct a potential problem with the aircraft performance.

Surveillance by the Civil Aviation Safety Authority

Evidence showed that some fellow pilots made unsuccessful attempts to dissuade him from his questionable take-off habit. The relevant Civil Aviation Safety Authority flying operations inspector had not been made aware of the pilot's technique of climbing steeply after take-off. If these events had been reported, an early investigation may have had the effect of modifying his flying techniques.

Weather

Witnesses at the air strip report that the wind was gusting occasionally. It is possible that a stronger gust of wind exacerbated the handling problem experienced by the pilot.

The pilot's flying habits probably resulted in the adoption of an excessively steep climb after takeoff.
The aircraft stalled at low altitude and struck the ground before the pilot could regain control.

At a result of the investigation into this occurrence, the Bureau of Air Safety Investigation forwarded the following interim recommendation to the Civil Aviation Safety Authority on 4 November 1996:

'IR960127

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

review the Aviation Safety Surveillance Program to ensure that new commercial operators are adequately monitored and inspected until a demonstrated history of safe operation is known;
align the scheduled surveillance period of the Aviation Safety Surveillance Program to that of the validity period of the air operators certificate;
reconsider the flight review requirements for Chief Pilots with the view of bringing them into line with the current situation for Chief Flying Instructors, as an additional method of surveillance;
review the adequacy of the approval and assessment requirements for Chief Pilots who do not have a demonstrated history in flight operations with a commercial operator;
review the current situation regarding Aeroplane Flight Reviews, to allow for appropriate notification to the Civil Aviation Safety Authority and recording of the results.'

Significant Factors

The pilot's flying habits probably resulted in the adoption of an excessively steep climb after takeoff.
The aircraft stalled at low altitude and struck the ground before the pilot could regain control.

Analysis

Aircraft performance

Contributing factors to the pilot's actions

Several factors appeared to contribute to the pilot's use of a steep climb attitude and his failure to detect or correct the potential problem in the aircraft's performance.

Firstly, the pilot appeared to believe that the aircraft was very stable and forgiving. This belief may have resulted in the pilot developing an undesirably low perception of the risk associated with some manoeuvres, particularly flying the aircraft with high rates of climb and low speeds after take-off. After repeatedly flying this manoeuvre without adverse consequences it may have become part of his normal behaviour.

One particular area in which the pilot appeared to have had limited understanding concerned the effect that different loads have on the aircraft's performance and capabilities. On the previous occasions in which the pilot was seen to have used a steep climb after take-off followed by an early turn, there had been no passengers. The aircraft weight was therefore significantly below the maximum allowable take-off weight. However, on the accident flight, the aircraft weight was above the maximum allowable take-off weight. With a heavier than usual aircraft, the performance would not have been what the pilot normally experienced. In addition, the centre of gravity was further aft on the joy flight compared to a pilot-only flight, resulting in a lighter elevator control. The pilot's low level of experience may have meant that he was less able to associate a problem with aircraft performance to the heavier than normal operating weight.

Surveillance by the Civil Aviation Safety Authority

Weather

Witnesses at the air strip report that the wind was gusting occasionally. It is possible that a stronger gust of wind exacerbated the handling problem experienced by the pilot.

Summary

The pilot had set up a small business conducting charter flights and towing advertising banners with his four-place aircraft. For 18 months he had operated from the airstrip near Dunwich, located in a shallow valley. The surrounding sand hills are timbered and shelter the strip from the full effects of the prevailing south-easterly winds.

Two families had earlier arranged a joy flight for three of their children. Due to adverse weather conditions, the pilot twice cancelled the proposed flight. On the day of the accident, the families met the pilot at Dunwich airstrip. He was waiting, standing near his aircraft with its engine running. After a short safety briefing, the passengers were seated and strapped in. The aircraft taxied to the northern end of the 800-metre airstrip where it held its position presumably while the pilot conducted pre-take-off checks. Witnesses heard the engine RPM change several times before the take-off roll commenced.

Witnesses reported that following a short take-off run, the aircraft climbed steeply at an angle of approximately 30 degrees. At top of climb, about 250 ft above ground level, the aircraft banked steeply to the left. The nose of the aircraft fell below the horizon during the left turn which continued through 150 degrees. The aircraft struck the ground, in a 50-degrees nose-low attitude, in low scrub 120 metres east of the airstrip. A fuel fire started almost immediately. The parents of the passengers and other bystanders ran several hundred metres to the crash site. Despite their efforts they were unable to free the occupants from the distorted structure. An intense fire drove them back and eventually burnt out the remains of the cabin.

Occurrence summary

Investigation number	199600094
Occurrence date	12/01/1996
Location	North Stradbroke Island
State	Queensland
Report release date	01/02/1999
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	PZL Warszawa-Okecie
Model	PZL-104
Registration	VH-PZS
Serial number	CF-15810600
Sector	Piston
Operation type	Charter
Departure point	North Stradbroke Island, QLD
Destination	North Stradbroke Island, QLD
Damage	Destroyed

Airborne Windsports Edge, T2-2669, Fawcetts Plain, Kyogle, New South Wales

Summary

History of the flight

The aircraft was one of a group of powered hang gliders operating from a 900-m grass strip aligned east-west. The group had arrived at the strip the previous morning. That afternoon, the pilot flew the aircraft with a passenger on a cross-country flight. Earlier, the pilot took another passenger for a flight which included power-on and power-off stalls. The aircraft performed normally on both these flights.

The group camped at the strip overnight and planned an early morning flight. However, the departure was delayed by fog. The aircraft had been left assembled overnight standing in the open. As a result, the wing had been wetted by condensation to the extent that beads of water had formed. Although the wing was exposed to direct sunlight for about 30 minutes before take-off, it was reported to have still been wet, although not beaded, when the aircraft taxied for take-off.

Conditions were suitable for flight by about 0930 EST. The understanding was that each aircraft would take off towards the west and climb straight ahead to 1,500 ft above ground level before flying back across the strip in an easterly direction.

The accident aircraft was the first to take off. The wind was calm. The aircraft became airborne after a normal ground roll and climbed straight ahead. As the climb progressed, the aircraft followed the normal procedure of positioning about 80 ft above the right side of the strip. (This procedure is conducted so that, in the event of an engine failure, the aircraft is in a position to turn left to land back on the strip.)

At an estimated 200 ft above ground level, the aircraft levelled and entered an abrupt right turn to head approximately north. At the same time, the engine noise decreased but then increased again as the aircraft began a shallow climb, still heading north. A short time later, the aircraft rolled sharply right to at least 45 degrees of bank and adopted a steep nose-low attitude. It then spiralled to the ground, completing about one and one-quarter turns before impact. Members of the group were in radio contact with one another. No transmissions were heard from the pilot during the take-off and accident sequence.

Witnesses described the turn onto north and the subsequent turn as unusually abrupt. One witness, who flew a similar aircraft, considered that the turns would have required considerable physical effort from the pilot to manoeuvre the control bar towards his chest and to the left. The pilot was described as confident and reliable. There were no reports of him acting impulsively while flying.

Assuming the aircraft was carrying full fuel for the flight, the calculated take-off weight was 387 kg. Maximum allowable take-off weight for the aircraft was 401 kg.

Wreckage examination

Examination of the wreckage did not reveal any pre-existing fault which might have contributed to the accident. Failures to the mast and front mast brace were caused by overload. A strip examination of the engine did not reveal any fault which may have precluded normal operation. Examination of a section of engine exhaust pipe confirmed that the engine was operating at impact.

Pilot's experience

The pilot had completed a training course on weight-shift aircraft (commonly known as Trike aircraft) about 18 months before the accident. This training was conducted in accordance with the Trike Pilot Training Syllabus issued by the Hang Gliding Federation of Australia (HGFA) and approved by the (then) Civil Aviation Authority. The pilot did not receive any training in recovery from spiral dives; nor did the syllabus include a requirement for such training.

Medical and pathological information

The pilot was reported to have been in good health on the morning of the accident. The passenger was suffering from a cold. Pathological examination did not reveal any pre-existing condition of the pilot or the passenger which might have contributed to the accident.

Extracts from Pilot's Handbook

Section 2, paragraph 2.1 of the Pilot's Handbook for the aircraft lists airspeed limitations including:

"Stall speed 30.3 knots (IAS) max weight (power off)

23.0 knots (IAS) min weight".

Paragraph 2.4, Other Limitations, includes the following:

"The effect of light rain on the aircraft is slight. Heavy rain will cause the stall speed to rise to the point where it is possible to stall the aircraft without banking the wing. Under these circumstances the pilot input for control in the roll axis increases.... Do not use waterproofing agents on the wing as the consequent beading of water droplets can significantly increase the stall speed.

Aerobatic manoeuvres including whipstalls, stalled spiral descents and negative G manoeuvres are not permitted. It must be emphasised that a whipstall, spiral descent, or negative G manoeuvre can never be conducted safely. These manoeuvres put the aircraft outside the pilot's control and puts [sic] both the aircraft and its occupants in extreme danger."

Aircraft handling characteristics

As part of the investigation, the Civil Aviation Safety Authority (CASA) was approached for information on the handling qualities of weight shift controlled (Trike) aeroplanes, including the type involved in the accident. As a result, a CASA test pilot undertook a limited flight evaluation and held discussions with experienced Trike pilots.

A test was conducted in which the aircraft was stalled and no roll correction applied. The Trike entered a spiral dive during which roll divergence and nose-down pitch increased. Large out-of-trim forces were felt as speed increased. This caused difficulty in maintaining a nose-up longitudinal control position. Roll control remained effective throughout the manoeuvre although response rate to a given control input decreased as the spiral developed. Rapid recovery from the spiral was achieved by relaxing the nose-up pitch input and rolling wings level.

The test pilot reported that discussions he had with experienced pilots indicated that the spiral dive was not a widely recognised condition among Trike pilots. If a wing drop at the stall was not corrected early, recovery from the spiral dive to normal flight could result in an altitude loss of up to 90 m. The recognition of, and recovery from, a spiral dive was not included in the Trike Pilot Training Syllabus. It was suggested that such training be included in the syllabus.

The test pilot considered that the accident aircraft may have stalled and entered a spiral dive. A reflex action of the pilot may have been to attempt to raise the nose of the aircraft to recover from the dive. However, although this would have involved very high control forces, such an action by the pilot would have maintained the wing in a stalled condition, causing the spiral to continue.

A further flight characteristic of the Trike was that aircraft response to control inputs was slower as speed decreased, and aircraft weight increased.

ANALYSIS

The evidence indicates that the aircraft entered a spiral dive which continued to ground impact. Without specific training in this area, the pilot probably did not have the experience or knowledge to apply to recover from the unusual situation the aircraft was in. From the witness reports, it could not be determined if the height above ground of the aircraft when it entered the spiral dive was sufficient to allow recovery to normal flight.

The two abrupt turns made by the aircraft shortly after take-off cannot be readily explained. The aircraft did not follow the planned departure procedure and there was no radio transmission from the pilot to indicate any problem. Further, the pilot had no record of impulsive behaviour during flight.

It is possible that the pilot was attempting to fly a circuit to land back on the strip, although no reason for such action was established. The take-off weight of the aircraft meant that the stalling speed was high. This may have been increased further by the remaining moisture on the wing. It is conceivable, therefore, that the aircraft stalled during the turn which led to the spiral.

It is also possible that the change in engine noise heard by witnesses when the aircraft turned onto north influenced the pilot's actions. However, the engine noise quickly recovered and there was no evidence of any fault in the engine. The change in noise could be explained by the pilot's foot slipping on the throttle pedal control. These facts weigh against the engine being a factor.

The flight tests indicated that wing drop accompanying a stall could lead to a spiral dive if roll correction was not applied. Although the response rate of the aircraft to control inputs would have been reduced at the operating weight of the aircraft, the pilot had recent experience in flying the aircraft (including stalling) at this weight. The entry of the aircraft into the spiral dive is, therefore, not readily explainable.

CONCLUSIONS

Findings

For reasons which were not established, the aircraft entered a spiral dive.
The pilot had not received training in recognising and recovering from spiral dives.
The height above ground available for the pilot to recover from the spiral dive was probably marginal.

SAFETY ACTION

During the investigation, close contact was maintained with the HGFA. The Federation was also informed of the results of the flight evaluation undertaken by CASA. In response to this information, the Federation issued in March 1996 an amendment to the pilot training syllabus for weight-shift aircraft to include steep turns as a training unit. One of the objectives of the unit is that the student demonstrate skills required to counter the spiral tendency of the aircraft following a stall during a steep turn.

A revised HGFA Weight shift Microlight Flying Instructor's Manual was issued. This included the following:

"Spiral Dive Tendency

Demonstrate the tendency for the aircraft to begin to "spiral" when excessive pitch pressure is applied with a nose down attitude in a steep turn. Demonstrate that the aircraft will recover from the spiral due to its pitch and roll stability, though height loss can be substantial if excessive pitch pressure is held until the aircraft stalls. Demonstrate that reducing pitch pressure and levelling the wings will reduce height loss.

"Demonstrate that though the aircraft's tendency to diverge in roll is slow, it will increase if the aircraft is held in this spiral mode. Demonstrate that the aircraft can be readily rolled level by easing pitch pressure and applying weight shift.

"Ensure that the student is able to recognise the onset of the spiral tendency and is familiar with the recovery techniques".

Occurrence summary

Investigation number	199502099
Occurrence date	09/07/1995
Location	Fawcetts Plain, Kyogle
State	New South Wales
Report release date	22/11/1996
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Airborne Australia
Model	Edge
Registration	T2-2669
Sector	Piston
Operation type	Sports Aviation
Departure point	Kyogle
Destination	Kyogle
Damage	Substantial

Cessna 172N, VH-FFZ, Uteara Station, 78 km west of Bourke, New South Wales

Summary

The aircraft was being operated on a flight over the pilot's property to inspect bores. It had been airborne for about 90 minutes.

The pilot contacted his son, who was mustering sheep on the property, on a hand-held radio to advise that he was returning to the station airstrip to refuel.

About three minutes later the crashed aircraft was observed by the pilot's son who had not seen or heard the aircraft immediately before the accident. The aircraft had impacted the ground in a near-vertical nose-down attitude and the pattern of damage to the left wing indicated that the aircraft had been rotating to the left when it struck the ground.

The pilot, the sole occupant, had sustained fatal injuries.

An inspection of the aircraft did not reveal any evidence of pre-impact defects. The engine was running at impact; some flap was extended and there was evidence of post-impact fuel leakage.

The pilot had completed a biennial flight review (BFR) in December 1994 and was correctly licensed to carry out an aerial inspection flight.

The nature of the impact indicates that the pilot lost control of the aircraft and was unable to regain control prior to impact with the ground.

The reason for the apparent loss of control was not determined.

Occurrence summary

Investigation number	199501063
Occurrence date	09/04/1995
Location	Uteara Station, 78 km west of Bourke
State	New South Wales
Report release date	19/03/1996
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Loss of control
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Cessna Aircraft Company
Model	172
Registration	VH-FFZ
Serial number	17268792
Sector	Piston
Operation type	Aerial Work
Departure point	Uteara Station, NSW
Destination	Uteara Station, NSW
Damage	Destroyed

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