FACTUAL INFORMATION

History of the Flight

At 0700 CST on 23 July 1992, two foreign national pilots, who were undergoing airline transport pilot licence training acquired the keys and documentation for TB20 aircraft VH-LQB in preparation for a daytime instrument flight rules (IFR) navigational exercise.

The aircraft departed at about 0930. After carrying out practice instrument approaches at several aerodromes along the route, they arrived over Ceduna at 1330 where an NDB approach was made before landing. While positioning the aircraft for refuelling a scraping sound was heard from the front of the engine. After the aircraft was refuelled and the engine restarted, the same noise was heard. An examination revealed that the starter motor was remaining engaged. The pilots contacted the operator and requested assistance. The operator despatched a maintenance engineer who replaced the starter motor.

The aircraft commenced taxiing at 1854. The pilot established radio contact with Adelaide Flight Service Unit (FSU) advising that he was taxiing for Parafield, IFR, and would be using runway 11.

A Cessna Conquest, VH-ANJ, commenced taxiing at 1859, with its pilot being unable to see VH-LQB take-off. He reported taxiing to Adelaide FSU and advised that his departure would be from runway 29. Approaching the threshold of runway 11 he noticed the navigation lights of VH-LQB as the aircraft climbed, and estimated the aircraft to have been at 100 to 200 ft above ground level. He then commenced to back track along the runway for a departure to the west.

Witnesses, located to the north of the Flinders Highway, noticed the lights of an aircraft departing from Ceduna Airport, tracking in an easterly direction. Although several kilometres away from the aircrafts track, they believed it was lower than normal, having watched many aircraft depart, including three or four that day. The aircraft lights then descended towards the ground and an orange flame appeared, followed by the sound of an explosion.

VH-ANJ informed Adelaide FSU that they had observed VH-LQB depart, and then saw a fireball appear in that direction. Adelaide FSUs were unable to contact VH-LQB. VH-ANJ was requested to locate the fire when airborne and direct emergency services to it. The fire was located approximately 5 km from the airport, 3 km to the right of runway 11 centre line. It was subsequently identified as the wreckage of VH-LQB.

Injuries to persons

Both pilots of VH-LQB were fatally injured.

Damage to aircraft

The aircraft was destroyed by impact forces and post-impact fire.

Other damage

There was no other damage.

Personnel information

The pilot-in-command held a current Private Pilot Licence with a Class 1 medical certificate, and a Command Instrument Rating for single-engine aeroplanes. He was qualified to fly the TB20 aircraft and had accumulated 61 hours on the aircraft type. His total flying experience was 189 hours, which included 26 hours of instrument flight time, 26 hours of simulated instrument flight time, and 11 hours of night flying experience. He last flew at night on 17 June 1992.

The other pilot held a current Private Pilot Licence with a Class 1 medical certificate, and a Command Instrument Rating for single-engine aircraft.  He was qualified to fly the TB 20 aircraft and had accumulated 65 hours on the aircraft type. His total flying experience was 192 hours which included 38 hours of instrument flight time, and 15 hours of night flying experience. He last flew at night on 14 July 1992.

Aircraft weight and balance

The weight and centre of gravity were within limits at the time of the accident.

Meteorological information

The Ceduna weather was fine with 1 octa of strato-cumulus cloud at 3500 ft. The wind was from 170 to 180 degrees at less than 5 kts. It was reported to be a very dark night with no discernible horizon. Moon rise was not until approximately 0100.

Wreckage and impact information

Ground impact marks indicated that the aircraft had been on a heading of 150 degrees in a shallow dive, with a bank angle of 15 degrees to the right, at an estimated speed of approximately 140 kt when it impacted the ground in an area of open pasture. The right wing separated from the fuselage. The aircraft continued in the southerly direction, breaking up as it went, with the cabin consumed by fire. Propeller contact with the ground caused a torsional failure of the crankshaft at the propeller attachment flange. The propeller travelled in a direction of 210 degrees for 65 m, leaving a trail of slash marks in the ground as it continued to rotate. The engine left wing and other components separated during the impact sequence. The engine bounced away on a curved track to the right for a distance of 110 m in a direction of 240 degrees from the main wreckage trail. The remains of the fuselage, consisting of the fire gutted cabin and tailplane, came to rest 166 m from the initial point of impact.

Fire damage was confined to the cabin area, which was totally consumed, except for the two instrument panels and co-pilot's seat, which were thrown clear.

No evidence was found to suggest a pre-existing defect in the aircraft structure or control systems prior to the accident. The propeller damage, condition of the engine and its components, and specialist analysis of exhaust pipe temperatures at impact, indicated that the engine was delivering power at impact. The temperature of the exhaust pipes was determined to be approximately 500 to 600 degrees Celsius at the time of impact. The vacuum pump frangible coupling, made from a ductile polymeric material, had failed under torsional load. Laboratory examination determined that there was no rotational damage to the failed coupling faces which indicated that the engine ceased operating immediately following the coupling failure.

Medical and pathological information

There was no evidence that either pilot had any medical or psychological condition which might have contributed to the accident.

Fire

A fierce fire, fuelled by aviation gasoline from the ruptured fuel tanks, engulfed the aircraft's cabin, reducing to ash the area between the engine firewall and the tailplane. The remainder of the wreckage suffered little or no fire damage.

Tests and research

Flight profile

A similar aircraft was used to attempt to replicate the accident flight profile from various altitudes. Six flights were conducted. The first flight followed the Ceduna to Adelaide track on climb to a point abeam the accident site. Normal climb power settings and speeds were used. The next four flights used a 10 to 15 degree angle of bank to the right, with the aircraft being held in a dive so as to arrive at the accident site without changing the climb power or trim settings during the descent. The final flight was conducted with power off and the controls left unattended from the top of climb.

The investigation was not able to establish the actual flight profile of the aircraft. However, from the flights it was considered possible that the aircraft may have descended from approximately 500 ft at an indicated airspeed of 140 kts.

The effects of somatogravic illusion were considered. Acceleration after take-off, into a dark horizonless sky accentuates the illusion giving the impression of a steep nose-up attitude. This illusion may cause a pilot to assume that the aircraft attitude is to nose high, and to respond by lowering the aircraft nose. However, studies have shown that this illusion is only likely to have an effect during the take-off rotation and initial climb phase of flight.

Attitude indicator

Tests were later conducted with a similar type of aircraft to establish the time for the attitude indicator to topple following a vacuum source failure.

This was simulated by ground running the engine at 2000 RPM for 5 minutes to ensure the gyro was fully erect, then shutting it down. This test, with a vacuum indication of 4.8 inches of mercury was conducted several times resulting in an indication of a bank to the left.

Gyro instruments

Detailed inspection of the gyro instruments failed to reveal any defects which may have prevented their normal operation.

Additional information

Following replacement of the starter motor the battery was found to be flat requiring the use of an external power source for starting. It was after last light by the time the repairs had been completed, and the pilot who had flown the aircraft to Ceduna carried out the engine run following the starter motor replacement. He then remained in the left pilot seat during the preparations for departure, as it was considered easier to leave the engine running than jump start it again, so by default he became the pilot-in-command for the return flight.

While talking to the pilots prior to departure the instructor who accompanied the engineer to Ceduna did not consider giving them a night operations briefing but was satisfied that they were capable of conducting the flight.

Flight and duty times

On the day of the accident the pilots had planned to complete the exercise during daylight hours. They had commenced duty at 0700, prepared and submitted their flight plan, checked the aircraft, then departed at approximately 0930.  One pilot being in command for the Adelaide to Ceduna sector, the other for the return sector to Adelaide. The flight to Ceduna took approximately 4 hours.

Training

Prior to commencement of night flying training, this operator ensured that all student pilots received classroom instruction in night flying techniques. In the syllabus of training the operator also covered the subjects of somatogravic and other illusions which can effect pilots under limited visual conditions.

The initial night flying training was carried out at Parafield, and students were subsequently taken to country airports, away from the lights of built-up areas, so they could experience dark night operations.

ANALYSIS

Following an apparent normal take-off the aircraft then descended back into the ground in what appeared to be controlled flight.

It is unlikely that the aircraft was lower than 500 ft above ground level when it commenced the descent. At this height the effects of acceleration and therefore somatogravic illusion would not be experienced by the pilot.

After becoming airborne the pilot may have become involved in recording the departure time, making a departure call on the CTAF, and changing to the Adelaide FSU frequency to advise them of the departure and next estimate, while failing to give sufficient attention to flying the aircraft.

At departure the pilots had been on duty for 12 hours, and it is possible that fatigue may have contributed to the accident.

The reason for the accident could not be established.

The aircraft was operating on to a 617 m grass strip with a fence at each end. The orientation of the strip was north/south and threshold markers were positioned on either side of the strip 79 m in from the fence at the northern end. Some 40 m beyond the southern end of the strip was a group of trees 14 m high.

The weather at the time of the accident was fine with good visibility. The Bureau of Meteorology estimated the surface wind to have been from the north-west at 12 kt. There was no windsock at the landing strip.

Observers saw the aircraft, apparently operating normally, fly towards the landing area and make an approach to land to the south. One witness said the aircraft touched down at the threshold markers. A second witness reported that the aircraft touched down about 200 m in from the fence, bounced to a height of 3-4 ft, then touched down again about 25 m further on. The witnesses then saw the aircraft continue along the strip at speed, with a significant level of engine power applied. Approaching the southern end of the strip, the aircraft swerved right, probably to avoid the group of trees beyond the end of the strip. The witnesses heard an increase in engine noise and saw the aircraft become airborne. The landing gear contacted the boundary fence, and the aircraft continued across a road, through a line of bushes, and struck the side of a house. An intense fire broke out, destroying the aircraft and much of the building. The pilot escaped from the wreckage, but the passenger did not.

The first marks identified on the airstrip surface were main wheel tyre tracks which commenced about 300 m from the threshold. These marks indicated that skidding had occurred from 350 m from the threshold and continued for about 50 m. From there the aircraft ran straight ahead for about 170 m before veering to the right by approximately 12-15 degrees. The tyre tracks continued to within about 20 m of the boundary fence.

Inspection of the wreckage did not reveal evidence of any defects that might have contributed to the accident. The landing gear was down, and the wing flaps were extended 17 degrees.

The Aircraft Flight Manual landing chart does not provide for landing distance calculation where the tailwind component exceeds five knots. The Beechcraft A36 Pilot's Operating Handbook indicated that, with a 10 kt tailwind and when approaching over a 50 ft obstacle, a landing distance of about 700 metres would be required. However, when approaching over a 20 ft obstacle, this distance is reduced to about 500 m.

The available evidence indicates that the pilot conducted an approach to land in a manner which was not appropriate in the prevailing conditions. The pilot misjudged the approach and touched down well into the strip. The decision to go-around was delayed until too late to safely complete the manoeuvre.

The pilot declined to make himself available for interview during the investigation.

Significant Factors

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

1. The pilot attempted a landing with a significant tail wind component.
2. The landing approach was misjudged.
3. An attempt to go around was made with insufficient airstrip remaining.

The Boeing 747 (QFA 27) was cleared for take-off from runway 16 on a Mudgee One Standard Instrument Departure (SID). This SID procedure required the aircraft to track via the 163 radial of the Sydney VOR (omni) to 3,000 ft and then turn left to track back towards the airfield, passing overhead the Sydney VOR prior to setting course in a north-westerly direction.

The VOR navigational aid is located on Sydney Airport and the SID required the B747 to be at 5,000 ft or higher before passing the VOR. Sydney Air Traffic Control had cleared the aircraft to climb to its initial cruising level, flight level (FL) 310. The Bell 206 (VH-BHU) planned to climb overhead Sydney Airport to FL 125 for a photographic operation.

The Sydney Aerodrome Controller (ADC) cleared the helicopter to climb to FL 125 within the lateral confines of an area between Qantas Maintenance facilities, located on the airport and the Sydney Hilton Hotel which is about 0.5 km west of the airport's northern boundary. Due to suppression of radar returns within 3.5 km of the radar head, which is also located on the airport, the flight path of the helicopter was not detected on any ATC radar screen.

VH-WGG departed Williamtown at 0703 hours and proceeded to track via the 015 radial of the Sydney VOR at 8,000 ft. The pilot contacted the Sydney Departures North controller 28 NM from Sydney and the radar identification was passed to the Approach North controller, who raised a 'shrimp boat' (a small piece of plastic which adheres to the radar screen and allows the controller to write pertinent information on it for his/her reference) and placed it on the radar screen next to the radar return of VH-WGG.

The shrimp boat was not positionally updated nor was it annotated to indicate to which aircraft it was referring. When an aircraft passes overhead Sydney, its track impinges on all four sectors of approach/departures airspace and two flight progress strips (FPSs) are raised, one for approach use and one for departures. These FPSs are pink in colour to enable them to stand out from the other FPSs in use.

The aircraft is identified by the controller in whose airspace it enters, and the progress is then monitored by all four controllers by updating the position of their 'shrimp boats' on the radar screen and placing the pink FPS in the central (active) strip bay.

The aircraft departed private property located at Tates Straight on Lake Burrinjuck NSW for Cootamundra NSW at about 1730 ESuT. On board were the pilot and two passengers. After take-off the helicopter was seen to transit at a low altitude in a northerly direction. Three to four minutes after the helicopter departed, witnesses heard a sound like a muffled gunshot and shortly after, smoke was seen to rise from the direction in which the helicopter was headed.

The accident site was located in a valley about 3.5 km from the point of departure. The ground level at the south end, the direction from which the helicopter approached, was the highest ground elevation along the flight path. From this point the valley floor descended relatively steeply, and the upper ridges of the valley sloped more gently with the distance between the ridges widening along the direction of flight. Trees about 15 m in height covered the valley and ridges

Weather conditions observed at the lake were fine with little or no wind.

The main aircraft wreckage was located in the centre of the valley. Wreckage was distributed for a distance of about 180 m in the direction of flight, from an area adjacent to the estimated position of a power line which was suspended across the valley. The majority of the wreckage was located under the flight path. However, the main rotor head with three blades attached, two separated main blades, and the tail rotor gearbox with damaged blades were distributed adjacent to the flight path. The fuselage and the main transmission were located about 180 m from the power line and were consumed by fire. The aircraft had descended at an angle of about 15 degrees through the tree canopy. After striking the ground, it slid about 10 m before coming to rest. The engine was located about 13 m beyond the fuselage. The three persons on board received fatal injuries.

About 1 km from the south end of the valley, a power line extended across the valley at right angles to the direction of flight. The power poles were located on the tops of each ridge which resulted in a wire suspension distance of about 832 m. The east ridge is about 510 m AMSL, and the west ridge is about 480 m AMSL. The wreckage was located at about 380 m AMSL or between 100 and 120 m below the ridge heights. The power poles were located in clear spaces among the trees at the top of each ridge and could only be observed from a position in line with the suspended wire. The conductor was 4.2 mm in diameter and constructed of three strands of steel wire. The wire sag was reported by the electricity company to be about 41 m. The conductor was broken.

Examination of the recovered fuselage and tail boom showed evidence of a wire strike to the area of the helicopter just above the cockpit and repeated main rotor blade strikes to the fuselage and tail boom. The wreckage scatter both in the trees and on the ground was indicative of an in-flight breakup. There was no evidence of in-flight fire.

The engine exhibited signs of high-speed rotation at impact and the damage was consistent with ground impact damage. Failues to the main rotor head, tail rotor and gearbox, and rotor blades were analysed as overload failures.

It could not be determined why the pilot departed to the north rather than to the north west direct to Cootamundra, nor why he was conducting the flight at an altitude which placed the aircraft below the valley ridge lines.

The sun was positioned left of and at near right angles to the direction of flight and would not have interfered with the pilot's vision. The wire conductor was dull and would not have reflected sunlight. Consequently, the wire would blend in with the background features of trees, grass, water and sky making it difficult for the pilot to see and avoid.

Evidence gathered at the accident site indicated that the helicopter struck the suspended wire conductor while in normal cruise flight at a height of about 60 to 80 m above the ground. Wire contact occurred first on the upper fuselage and then on the main rotor head. The contact would have applied abnormal gyroscopic loads to the main rotor disc. These loads would result in the blades travelling outside their normal paths and striking the helicopter fuselage and tail boom. Metal components recovered from the fuselage and tail boom, and main rotor blade damage, indicates that there were multiple main rotor blades strikes on the aircraft structure. The main and tail rotors separated from the helicopter before it descended into the trees.

Significant Factors

1. The aircraft was being flown at low altitude and struck a power line.

2. An in flight breakup of the helicopter occurred.

The pilot had planned to carry out a period of circuit training. Following discussion with the operator it was decided, primarily at the pilot's request and because of apparent under-confidence and a concern she had about recency, that her circuit procedures would be checked by an instructor prior to conducting solo circuit training.

Two uneventful dual circuits were conducted. Following the dual check the pilot carried out one solo circuit which resulted in a normal landing, a second circuit which required an overshoot as the aircraft was too high over the threshold, and a third circuit which appeared normal. The accident occurred on the fourth solo circuit.

During the fourth circuit the aircraft was observed to be below the normal glide path and flying faster than normal as it turned on to the final approach. The aircraft continued to descend, with wing flaps retracted, until it became obvious to the ground observers that the aircraft would crash short of the runway unless the pilot took corrective action.

Just prior to impact the pilot radioed that she was "going round". However, the aircraft collided with a 15 metre high tree 300 metres short of the threshold, as the call was being made. The aircraft came to a stop inverted, in a drain, 30 metres beyond the tree.

Insufficient evidence was available to determine the precise factors which led to the accident. Weather and mechanical problems were eliminated as possible factors. It is apparent from the aircraft's final flight path and the timing and tenor of the "going round" call that the pilot was unaware of the danger until just prior to impact.

The pilot was conducting a rice sowing operation and had entered the procedure turn on completion of the first swath run of his first load for the day. The aircraft appeared to be operating normally at about 300 ft, however, as it turned back towards the treatment area it was seen to overshoot the alignment for the reciprocal swath run. The nose then pitched down, and the engine noise was heard to increase significantly as the aircraft descended to the ground at a steep angle.

A small fire in the engine area was extinguished by the two markers, who arrived from the treatment area within minutes of the impact.

The aircraft had struck the ground in a left wing low, steep nose-down attitude. The left wing folded up against the fuselage and the engine was displaced to the right. Impact forces were high, causing major disruption to the fuselage, although the cabin area dimensional and structural integrity remained substantially intact.

No evidence of a pre-impact failure was found in the aircraft or its systems.

The weather conditions were fine and calm.

Findings

1. In an attempt to regain the alignment for the reciprocal swath run, the pilot tightened the turn, causing the aircraft to stall and enter an incipient spin to the left.

2. The height available was insufficient to permit the pilot to regain control of the aircraft.

Significant Factors

1. The aircraft stalled at a height from which the pilot was unable to effect a recovery.

Safety Action

During this investigation it was identified that the aircraft was fitted with an American Safety Inertia Reel Pt No 7260111-405 which does not comply with the requirements of CAO 101.17 for agricultural operations.

It is therefore recommended that the Civil Aviation Authority:

1. Advise agricultural operators that American Safety Inertia Reel Pt No 7260111-405 does not meet the requirements of CAO 101.17 para 5.9.3, and

2. Take steps to ensure that inertia reels which are fitted to aircraft engaged in agricultural operations do comply with the requirements of CAO 101.7 para 5.9.3.

On 19 June 1992, at approximately 1853 hours, a Beechcraft Baron 95-B55, registration VH-JDL, disappeared from Air Traffic Control radar display, without prior indication of difficulty. The aircraft wreckage was located the following morning on a moderately timbered slope, 700 metres above mean sea level and 45 kilometres north-east of Canberra, Australian Capital Territory.

The pilot and all five passengers were killed and the aircraft was destroyed by impact forces. The investigation determined that the aircraft departed Bankstown Airport loaded in excess of the maximum allowable take-off weight, and that the pilot did not comply with either Instrument Flight Rules or Night Visual Flight Rules rating recency standards required for the conduct of the flight.

While cruising at 8,000 feet, the aircraft entered a rapid descent, during which it reversed direction in a left turn. The descent was briefly arrested at a low altitude, however, the aircraft again turned left and descended rapidly. The aircraft exhibited flight characteristics consistent with those of an aircraft loaded to an aft centre of gravity position. There are indications that the centre of gravity moved further aft during the flight, until reaching a point at which the pilot was unable to prevent significant diversions in both climb and descent from the reference altitude, culminating in the rapid descent.

At approximately 1236 EST, tug VH-KKZ took off towing glider VH-GQR which was towed north of the airfield to a height of 2000 ft, before releasing from the tug. The barograph trace from the glider showed that it had not encountered any thermal activity and was continually descending after release from the tug.

At approximately 1240, tug VH-UTK took off towing glider VH-GZR which was towed north of the airfield to a height of 2200 ft, before releasing from the tug. After the glider released, the tug descended and returned to the airstrip via a standard recovery pattern.

When the glider VH-GQR was first seen by a witness, it was north of the field on the downwind leg of the circuit pattern at approximately 400 ft. The weather conditions at the time were fine, with high-level cirrus cloud. The witness monitored the progress of the approach and assessed that the glider was lower and closer to the airfield than for a standard circuit. The glider flew a close oblique base leg for strip 09, positioning for landing.

Coincident with the approach of the glider to strip 09, tug VH-UTK, was returning to the airfield for runway 09 after releasing the glider VH- GZR. The tug had turned onto an extended final approach at 900 ft. Approaching 500 ft, the pilot lifted the left wing to check for conflicting traffic turning base for runway 09. The pilot did not see any traffic so continued the approach and at approximately 300 ft, had a momentary glimpse of the glider above the aircraft as they impacted.

The two aircraft remained together momentarily, until the glider separated from the tug and fell away having been cut in two by the propeller of the tug.

Both aircraft were fitted with an aviation transceiver, however no radio transmissions were heard from either pilot. The tug radio was reported to have been on at the time of the accident. The glider radio was recovered from the aircraft for laboratory examination, but due to the extensive damage to the unit, no meaningful information could be acquired from the unit.

Engineering analysis of the glider wing that had sustained propeller slashes, determined that the glider descended onto the left side of the tug, in a wings-level attitude, skidding to the right. The glider had an overtake speed of approximately five knots with a nose-down attitude of three degrees relative to the longitudinal axis of the tug.

Analysis

The aircraft were operating in an un alerted see-and-avoid environment. The tug was a high-wing aircraft, with a resultant masking of upward vision. The expectation of the tug pilot was to have conflicting traffic coming from a standard circuit, however, the accident glider was conducting a non-standard circuit. The glider was painted white and had minimal contrast against the sky background with the sun overhead. For much of the time preceding the impact, the aircraft were on constant tracks with little relative movement to aid visual detection. The combination of the foregoing factors and the final manoeuvring of the glider placed both pilots in the situation of not being able to sight each other. The use of radio would have alerted the pilots to the presence of the other aircraft in the circuit, and would have added to the safety net.

The pilot landed on the property airstrip in order to correct a problem he was having in communicating with Canberra Air Traffic Control (ATC). Apparently having made adjustments to the radio installation, the pilot attempted to hand start the engine, but had not succeeded before he was met by the property owner and an employee who then provided some assistance. With the engine restarted, the pilot advised Canberra ATC by relay through an aircraft tracking from Goulburn to Canberra of his intention to depart. He was instructed to call again after take-off.

After take-off from the airstrip, the aircraft overflew the property owner as it turned onto a southerly heading. The aircraft was then observed to adopt what appeared to be a nose high attitude as it flew away from the strip. At a height of 200-300 feet, the aircraft was seen to commence a steep descent, while rotating to the right. The descent was not checked before the aircraft impacted the ground, right wing low, in a near vertical attitude.

No radio transmissions were heard from the pilot following take-off.

The report of the autopsy conducted on the pilot indicated that he had suffered a physical incapacitation before the aircraft impacted the ground.