Collision with terrain

Bell 206B (III), VH-AZH, collision with water, Bendora Dam, Australian Capital Territory, on 13 January 2003

Summary

The Bell Helicopter Company, JetRanger III helicopter was engaged in water-bombing in support of fire fighting operations in the vicinity of Bendora Dam, about 37 km southwest of Canberra. A Bell 412 helicopter, with a pilot and crewman on board, was conducting water-bombing operations in conjunction with the JetRanger. An Aerospatiale A350 Squirrel helicopter had recently returned to the area of operations and was conducting a survey of the Bendora fire zone.

The pilots of the two water-bombing helicopters had seen each other as they passed on opposite legs of a racetrack pattern between the fire and the dam. As the Bell 412 returned to the dam for water pick-up, the pilot noted the absence of the JetRanger during that pattern. At about 1238 Eastern Standard Time, the Bell 412 pilot unsuccessfully attempted to contact the JetRanger pilot on the radio. A short time later, the pilot of the Bell 412 noticed the upturned fuselage of the JetRanger in the water. He immediately broadcast a PAN call, and contacted the Squirrel pilot to advise that the JetRanger was in the water.

The Bell 412 pilot released his water bucket on the shore of the dam and established a hover close to the upturned helicopter. The crewman entered the water and freed the unconscious pilot from the wreckage. The Squirrel arrived at the dam and landed on the shoreline and two of the occupants entered the water to assist the crewman, who was experiencing difficulty keeping the pilot afloat during the rescue. Once on the shore, the pilot was resuscitated before being transported to a Canberra hospital. There were no known witnesses to the accident.

The JetRanger helicopter was substantially damaged in the accident. Examination of the helicopter indicated impact with the water in a slightly right side down, nose-low attitude. Damage to the main and tail rotor systems indicated that both rotors had been under power when the helicopter impacted the water. Rotational damage to the engine compressor and turbine assemblies confirmed engine operation on impact with the water. Advice from the engine manufacturer indicated that the engine was probably producing above flight idle power at that time. There was no evidence of any pre-impact engine or other aircraft abnormality that would have contributed to the development of the occurrence.

A main rotor blade impacted the pilot's upper doorframe, and the right upper overhead window. There was also impact damage evident on the pilot's helmet, consistent with the helmet being struck either by the door frame structure or a main rotor blade.

An estimated 135 L (107 kg) of fuel was on board the helicopter at the time of the occurrence, which was sufficient for the planned flight. A sample of that fuel was sent to a laboratory in Melbourne, Victoria, for analysis. That analysis confirmed that the fuel was free from contamination and of the correct type. Along with a number of other helicopters, the JetRanger had been refuelling from a mobile tanker. None of the pilots of those helicopters reported any fuel-related problems during the day's operation.

The occurrence bucket attached to the JetRanger was placarded as a `Bambi Bucket' model 1012. The company operations manual did not list the 455 L capacity, 1012 model bucket for use and instead described the 545 L capacity, 1214 model bucket for use by company aircraft when conducting water-bombing operations. The bucket manufacturer left the choice of bucket for use when fire-bombing with the operator. However, the bucket manufacturer did not suggest either of the 1012 or 1214 buckets for use with the JetRanger. Instead, the manufacturer recommended use of the 410 L capacity, 9011 model bucket.

The bucket was attached to the JetRanger's cargo hook by a 24 m steel cable. Electrical wiring was fixed to the cable to allow operation of the water release mechanism by the pilot and, when required, to enable the addition of fire retardant foam. The cargo hook unit included a manual and electrical release, to enable pilot-activated release of the bucket and cable. The helicopter's cargo hook electrical release circuit breaker was found in the open-circuit position. As part of the investigation, the circuit breaker was reset and the cargo hook release was tested electrically and manually. While it could not be determined whether the as-found position of the circuit breaker resulted from pilot selection or the accident, both release mechanisms operated normally during subsequent testing.

An internal `cinching strap' controlled the volume of an `as-manufactured' `Bambi Bucket' via a series of metal `D' rings positioned along the length of the strap. That allowed selection of 70%, 80% or 90% of bucket capacity. Nylon webbing loops stitched to the inside of the collapsible synthetic bucket positioned the strap inside the bucket. The bucket strap fitted to the occurrence bucket was non-standard and did not include any `D' rings. Instead, the strap had been tied off with a knot. That was contrary to the bucket manufacturer's Repair Assessment Manual¹ that stated that it was not an acceptable practice to tie knots on the strap. The manufacturer cautioned that such actions may result in a false indication of the actual maximum volume of water in the bucket. Following consultation with the bucket manufacturer, it was determined that the bucket was of a non-standard construction.

Examination of the occurrence bucket revealed that several of the nylon webbing loops had been torn from the inside of the bucket. The investigation was unable to determine when the webbing loops failed. The bucket's capacity was 420 L measured in the as-found condition. During that test it was noted that the `cinching' strap exerted no influence on the bucket's volume due to the torn webbing loops. Post accident testing of the bucket's electric water release mechanism was carried out utilising the helicopter's electrical system. That test revealed that the bucket's mechanism operated normally.

The JetRanger pilot held a current Commercial Pilot (Helicopter) License and a valid medical certificate. He had a total of 6,713 hours total flying experience, with in excess of 2,917 hours on type. He was appropriately endorsed for, and very experienced in, fire fighting and long-line operations. The pilot was reported to be medically fit for the flight.

The pilot sustained traumatic head injuries and was submerged for an undetermined period. During subsequent interviews he was unable to recall any details of the accident.

The all up weight for the helicopter, including the 420 L of water carried in the non-standard 1012 model bucket, was estimated to be about 3,309 lbs. The maximum take off all up weight for the ambient conditions was estimated to be about 3,320 lbs.

The helicopter's centre of gravity was estimated to have been within limits.

The Bureau of Meteorology forecast for the Bendora Dam area indicated an east-northeasterly wind at a speed of 15 kts. Other helicopter pilots operating in the area on the day reported winds that varied in direction and strength. Visibility was reported as `good', with some smoke in the area. The investigation was unable to determine the actual wind direction and speed at the time of the accident.

Federal Aviation Administration Advisory Circular AC90-95 described the conditions under which a loss of tail rotor effectiveness (LTE) can occur. Included among those conditions were: high all up weight; out of ground effect hover; low forward airspeed; high power settings; and a wind direction from the left or rear of the helicopter. LTE can result in a loss of control.

The `Bambi Bucket' Manufacturer's Operator's Manual² warned pilots not to execute 90 degree pedal turns when the helicopter was close to the water and towing the bucket. That warning highlighted the danger of the bucket suspension lines becoming caught on the rear of a landing gear skid, resulting in a dynamic rollover when lifting the bucket. Federal Aviation Administration Advisory Circular AC 90-87 indicated that dynamic rollover normally occurred during slope landings and take-offs, with some degree of bank angle or side drift, with one skid in contact with the ground. In that case, the in-contact skid acted as a pivot point. If an excessive roll rate was permitted to develop around that pivot point, a critical bank angle could be reached where roll could not be corrected, even with full lateral cyclic. The helicopter would then roll over onto its side.

Other water-bombing pilots reported that, on previous sorties, the JetRanger pilot had been lowering the bucket vertically into the water to fill from an out of ground effect (OGE) hover, and then lifting it clear vertically before transitioning to forward flight. Underwater photographs of the helicopter showed that the bucket cable was not positioned over the rear of the skid assembly. Examination of the helicopter's landing gear skids did not reveal any damage from the bucket cable.

There was no system in place to track the fitment and maintenance of the company's cargo hooks.

Civil Aviation Order (CAO), 20.11, 5.1.1(a), stated that:

`Aircraft shall be equipped with one life jacket for each occupant when the aircraft is over water at a distance from land:
(a) in the case of a single engine aircraft - greater that that which would allow the aircraft to reach land with the engine inoperative...'

Para 5.1.7 of the CAO stated, in part:

`Where life jackets are required to be carried in accordance with subparagraph 5.1.1(a) each occupant shall wear a life jacket during flight over water...'

The pilot was reported to have been conducting his water pick-ups from close to the shoreline of the dam. The pilot was not wearing a personal flotation device (PFD) at the time of the accident.

A Flight Safety Foundation report - External Loads, Powerplant Problems and Obstacles Challenge Pilots During Aerial Fire Fighting Operations, based on USA accident reports from 1974 to 1998, stated in part:

`Research has shown that the average person, when immersed in cold water, can hold [their] breath for 17.2 seconds, plus or minus 3.7 seconds. Studies of water accidents involving military helicopters and civilian helicopters, however, show that successful underwater escape requires 40 seconds to 60 seconds'.

Helicopter underwater escape training (HUET) teaches pilots, other aircrew and passengers an instinctive escape procedure providing them with an improved chance of survival in the event of a helicopter ditching into water. The pilot reported that he had not undertaken HUET.

Analysis

The pilot was qualified and authorised and had recent experience for the operation.

The helicopter had sufficient fuel of the correct type on board for the flight. Rotational damage to the main rotor system and engine was consistent with engine operation at the time of impact.

The helicopter was at high all up weight and operating close to maximum predicted performance in an area with reported variable winds. While those conditions would have increased the risk of encountering LTE, the pilot was highly experienced in long-line and water-bombing operations and had been operating in the area of Bendora Dam for most of the day. That experience should have mitigated the risk that LTE was a factor in this occurrence.

Although of a non-standard construction, the occurrence bucket was assessed as being capable of normal operation, and was able to be carried by the helicopter at its post-accident assessed capacity. There was no evidence that it contributed to the accident.

While the manufacturer of the 'Bambi Bucket' warns of the possibility of dynamic rollover when conducting water-bombing operations, the use of a 24m long-line by the pilot, and vertical water pick-up would have diminished the likelihood for that to have occurred in this occurrence.

The investigation could not confirm the position of the cargo hook release circuit breaker prior to the accident. Had the circuit breaker been in the open-circuit position the rapid release of the bucket by the pilot, such as in an emergency situation requiring jettison of the load, would not have been possible.

The nature of the helicopter's impact with the water, and the resulting damage sustained by the pilot's helmet, reinforced the protective benefits of the use of flightcrew helmets.

It is possible that, during the water pick-up, the pilot may have been at a distance from the shoreline from which, had an engine failure occurred, the helicopter would not have been able to reach land. In that case, the provisions of CAO 20.11 would have applied, requiring the pilot to wear a PFD. That would have greatly eased the difficulty experienced by the helicopter crewman and others performing the rescue and, potentially, lessened the severity of the pilot's injuries.

Given the absence of pilot recollection and witness reports of the accident, and the lack of detailed indications of operation of the helicopter at impact, the reason(s) for the accident could not be established.

While recognising that, in this accident, the pilot was rendered unconscious and therefore unable to exit the helicopter without assistance, the ATSB draws attention to the benefits of HUET. Studies have shown that escape from helicopters involved in water accidents can take longer than the average time that a person can hold their breath. HUET has been shown to decrease exit times from an immersed helicopter, and increase the likelihood of a successful exit by an uninjured occupant. The provision of HUET to pilots, aircrew and passengers regularly operating over significant expanses of water would maximise the possibility for the successful exit of occupants from an immersed helicopter.

Safety Action

Local safety action

The operator has amended the company's operations manual to correctly reflect the types of fire buckets used on the company's individual helicopter types.

The operator has standardised the position of the external load jettison switch on the different helicopter types used by the company in fire fighting operations.

The company's operations manual now details the type of safety clothing to be worn by pilots when engaged in water-bombing operations in company helicopters. The clothing specified includes the wearing of cotton or better, flying suits, approved helmets and comfortable fitting life jackets. Inflatable life jackets have been positioned in each helicopter for that purpose.

The operator has introduced a system for tracking the fitment and maintenance history of cargo hooks fitted to company helicopters.

ATSB safety action

In a briefing to the Civil Aviation Safety Authority, the ATSB drew attention to the fact that the occurrence bucket was not of standard manufacture, and highlighted the possible effects of the use of non-standard buckets by helicopters during fire fighting operations.

As a result of this occurrence, the Australian Transport Safety Bureau issues the following safety recommendations:

Recommendation R20030219

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority, in conjunction with the relevant industry associations, highlight the safety benefits to helicopter pilots and crew of the wearing of personal protective equipment, such as helmets and personal flotation devices when carrying out water-bombing in support of fire fighting operations, through safety promotion initiatives.

Recommendation R20030220

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority, in conjunction with the relevant industry associations, assess the desirability of a requirement for Helicopter Underwater Escape Training for specialist aerial work operations, such as water-bombing in support of fire fighting operations.

Recommendation R20030221

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority, in conjunction with the relevant industry associations, consider advising Australian helicopter operators involved in water-bombing in support of fire fighting operations, of the need to review the type of fire-buckets used to ensure that they comply with the bucket manufacturer's guidance for use on helicopter types and to ensure that the fire-buckets are appropriately maintained.

¹ Issue Date: January 2003.
² Issue Date: May 2002.

Occurrence summary

Investigation number	200300011
Occurrence date	13/01/2003
Location	Bendora Dam
State	Australian Capital Territory
Report release date	16/12/2003
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Serious

Aircraft details

Manufacturer	Bell Helicopter Co
Model	206
Registration	VH-AZH
Serial number	3075
Sector	Helicopter
Operation type	Aerial Work
Departure point	Canberra, ACT
Destination	Canberra, ACT
Damage	Substantial

Cessna 210K, VH-RTH

Summary

The commercial pilot had hired a privately owned Cessna 210 for a flight to Killiecrankie on Flinders Island with two family members and two friends. After arriving overhead, the aircraft was positioned on downwind for a downhill landing on strip 27 at Killiecrankie. The pilot commented that there appeared to be no wind, which he determined from the windsock and the conditions prevailing on the ground, from the water in the bay and the stillness of the trees. A pilot on the ground, who is the owner of and responsible for the airfield maintenance and who witnessed the accident, reported that the wind was easterly at about 15 knots at tree top height, although probably less on the ground. The witness said that the sock was damaged, but it was still possible to determine the wind direction from environmental cues.

A passenger on the aircraft reported that he did not detect any indications of strong wind on the surface of the water or significant movement of the trees or foliage as the aircraft approached the threshold of the strip.

The pilot reported that on late downwind he configured the aircraft for landing with the first stage of flap and landing gear extended and turned the aircraft onto the final approach at approximately 800 ft above ground level. Although this was higher than normal for a turn onto final, he considered it to be okay. Full flap was lowered and the power reduced for landing.

As the aircraft neared touchdown well down the strip, the pilot considered it to be a late landing but still with sufficient length remaining for braking. The aircraft touched down and bounced twice into the air before the pilot applied power for the go-around. The witness reported that the aircraft initially touched down about two thirds of the way along the 1,400 metre strip before bouncing and then going around.

The pilot reported that although he applied full power, the aircraft did not accelerate to take off speed and did not gain sufficient height to clear the trees beyond the end of the strip. The passenger reported that as the aircraft approached the end of the strip during the go-around, it appeared to dip slightly as if affected by a gust of wind. The aircraft impacted the trees in a nose-up, wings-level attitude at full power, before the pilot reduced the power to idle. The fuselage remained upright during the impact sequence.

While the evacuation was taking place the aircraft began to burn and as the last passenger was exiting, the aircraft was almost totally engulfed in flames. All passengers evacuated through the main doors. The post-impact fire destroyed the aircraft. The pilot reported that prior to the flight he had thoroughly briefed the passengers on the emergency exits and the evacuation procedure.

The pilot later commented that he felt that the following factors contributed to the accident:

Although he had landed at Killiecrankie before and was aware of the downhill slope to the west, it was about 12 months prior to the accident.
The damaged windsock did not display the wind strength as accurately as an undamaged windsock would have.
He unwittingly initiated a tailwind go-around with insufficient strip remaining.

Occurrence summary

Investigation number	200205901
Occurrence date	17/12/2002
Location	Killiecrankie (ALA)
State	Tasmania
Report release date	20/05/2003
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Serious

Aircraft details

Manufacturer	Cessna Aircraft Company
Model	210
Registration	VH-RTH
Serial number	21059327
Sector	Piston
Operation type	Private
Departure point	Latrobe Valley, VIC
Destination	Killiecrankie, TAS
Damage	Destroyed

Cessna 182B, VH-PDK

Significant Factors

The weather conditions at the time of the accident were favourable to the development of lee waves and strong downslope winds in the vicinity of the airstrip.
The aircraft banked steeply out of wind, while at low airspeed and a low height.
The aircraft stalled at an altitude from which recovery by the pilot was not considered possible and control of the aircraft was lost.

Analysis

Witnesses observed the C182 at low altitude on approach to Turalla. Their reports that the wings were rocking from side to side were consistent with the turbulence that may have been produced in the lee of the escarpment by the strong wind. Down draughts and rotor turbulence could have resulted from the vigorous airflow at right angles to the escarpment, immediately to the west of the airstrip, and existed for a considerable distance downwind of the escarpment.

An approach to land in those conditions should not have placed any exceptional demand on the pilot's skill. The strip was aligned nearly into wind and the pilot was familiar with both the airstrip and the aircraft. The pilot had probably flown from the airstrip in similar conditions previously and should have been aware of the potential for turbulence and down draughts. The landing distance available was more than adequate for the aircraft type.

In turbulent conditions a pilot can elect to use less than maximum flap, or even no flap for the approach and landing. In a strong headwind, this would not significantly increase the aircraft's landing distance. Using less than full flap on the C182 can improve aircraft handling in turbulence. However, using less flap at lower airspeeds and higher angles of bank, significantly increases the aircraft stall speed.

Although the reason the approach was discontinued was unable to be determined, it was possible that the approach became unstable in the turbulence with airspeed fluctuations. The pilot appeared to have turned right to initiate a low-level circuit. Familiarity with the airstrip and anticipating turbulence in the lee of the escarpment may have been the reason that the pilot initiated a right turn rather than climbing straight ahead, which could have placed the aircraft into an area of increased turbulence. The direction of turn was consistent also with the pilot turning away from the glare of the setting sun. The pilot's memory of his siblings' accident may have influenced the decision-making process to make a rapid escape from the area of turbulence.

Witnesses reported that the aircraft's angle of bank was between 60 and 80 degrees when the approach was discontinued. There was no apparent reason for a steep turn to be made. There was no necessity for the pilot to rapidly make another approach and landing. There were adequate margins for both daylight and fuel.

The altitude at which the aircraft was seen to be operating would probably not have been sufficient to allow recovery from a stall, even with a pilot proficient in the technique. It was also possible that at the extreme angles of bank, a sudden loss of lift resulting from windshear or turbulence, or a rapid retraction of the manually operated flaps, could have placed the aircraft in a stalled condition from which recovery would have been unlikely at such a low height.

Factual Information

History of the flight

The pilot of the Cessna 182B Skylane (C182), with one passenger on board, departed Leongatha aerodrome in Victoria at about 1530 Eastern Standard Time (EST). The pilot planned the private flight in accordance with the visual flight rules to track coastal to Moruya and then via the Araluen Valley to 'Turalla', a private property located approximately 3 km northwest of Bungendore, NSW. The aircraft carried sufficient fuel for the flight.

Witnesses reported that, at about 1755, the aircraft overflew a property belonging to a relative of the pilot 3 km to the southeast of Bungendore, at about 500 ft AGL. That relative had been nominated as the responsible person to hold and cancel the nominated SARTIME of 1820. The aircraft was then observed to track west towards the Kings Highway, at a low level, and make a right turn to join a wide left base for the grass airstrip located at 'Turalla'. The airstrip was aligned approximately 305 degrees M. The aircraft was observed to turn left onto final approach at about 50-80 ft AGL. Witnesses reported that all turns were made using about 45 degrees angle of bank. Witnesses also observed the aircraft to be buffeted by gusting winds.

The weather at the time was reported by witnesses to be clear conditions with some upper level cloud. Winds were strong and blustery, from the west and northwest. A Bureau of Meteorology assessment of the weather indicated gusty north-westerly winds backing to the west after the passage of a front, which had occurred earlier in the day. The general wind structure lent itself to at least moderate turbulence and the strong possibility of lee waves and strong downslope winds.

While on short final, the aircraft was observed to make a steep climb towards a downwind position, turning to the right using 60-80 degrees angle of bank. It was then observed to lose altitude rapidly. It turned through about 295 degrees before impacting the ground approximately 300 m east-north-east of the airstrip threshold. The aircraft struck the ground at a 60-80 degree nose down, left wing low, attitude on a heading of about 240 degrees M. The aircraft was destroyed by impact forces and post-impact fire.

Injuries to persons

The passenger was fatally injured. Autopsy and toxicological tests conducted on the passenger revealed a low level of carbon monoxide in the blood. Medical opinion indicated that death occurred prior to the commencement of the post-impact fire. The pilot was seriously injured and survived the accident for 68 days before succumbing to the effects of his injuries.

Annex 13 to the Convention on International Civil Aviation, Aircraft Accident and Incident Investigation, defined a fatal injury as an injury that resulted in death within 30 days of the date of an accident.

Wreckage and impact information

A post-impact fire consumed the cockpit area. The extent of the fire damage precluded a productive examination of the cockpit, controls and instruments. Many of the alloyed components had been reduced to a molten state. Examination of the wreckage indicated that at the time of impact the aircraft was not configured for landing. The wing flaps were set to the retracted position. The engine was removed from the accident site for technical examination. The examination determined that the engine was capable of normal operation prior to impact and that it was producing power at the time of impact. Nothing was found during the investigation to suggest that mechanical failure of any part of the aircraft could have contributed to the accident.

Personnel Information

The pilot held a current private pilot's licence, was endorsed on the aircraft type and familiar with the landing area. A review of the pilot's personal flying logbook indicated that he had accumulated in excess of 340 hours total time, most of which were accrued on the occurrence aircraft. Four days prior to the accident, the pilot had satisfactorily completed a biennial flight review. The pilot held a valid Class 2 Aviation Medical Certificate. The pilot had just completed a short hiking holiday and there was no evidence to indicate any physical or psychological conditions that may have adversely affected his ability to pilot the aircraft.

Landing area

The landing area at Turalla was inspected after the accident. With the exception of a centrally located windsock, there were no aerodrome markings to detail the exact location and dimensions of the airstrip. There was evidence of recent aircraft use on the grass strip. The landing distance available was approximately 800 m, orientated approximately 305 degrees M. There was no evidence to indicate that livestock had been grazing on the paddock that contained the airstrip in the past month. A north-south ridgeline was located approximately 1 km to the west of the airstrip. At the time of the accident, the sun was setting in the west and was visible above the horizon.

Previous occurrence at the airstrip

One of the pilot's brothers and a sister were fatally injured in a separate aircraft accident (Bureau of Air Safety Investigation Report No. BO/199603734) in the vicinity of the same airstrip in 1996, when similar wind conditions were experienced. On that occasion, the Cessna U206F (C206) aircraft was climbing on departure from Turalla when the pilot turned left onto downwind. The C206 stalled at a height from which it was not possible to recover.

Summary

Occurrence summary

Investigation number	200204663
Occurrence date	13/10/2002
Location	2 km W Bungendore
State	New South Wales
Report release date	18/07/2003
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Cessna Aircraft Company
Model	182
Registration	VH-PDK
Serial number	51673
Sector	Piston
Operation type	Private
Departure point	Leongatha, VIC
Destination	Turalla, NSW
Damage	Destroyed

Piper PA-32-300, VH-MAR

Summary

At about 1708 Eastern Standard Time (EST) on 26 September 2002, the pilot of a Piper PA-32-300 (Cherokee Six) aircraft, registered VH-MAR, reported taxiing for departure from runway 14 at Hamilton Island, Queensland. The charter flight was to Lindeman Island, a distance of about 15 km to the southeast. On board the aircraft were the pilot and five passengers.

Witnesses to the east of runway 14 at Hamilton Island reported that, shortly after the aircraft became airborne, the engine began coughing and misfiring, before cutting out and then starting again. Shortly after, the aircraft commenced a right turn, and the engine was heard spluttering and misfiring. Witnesses reported that, when part way around the turn, the engine again cut out, and the aircraft descended and impacted the ground.

The aircraft came to rest upright, aligned in an east-north-easterly direction, approximately 300 m to the west of the runway centreline and approximately 100 m south of the departure end of the runway. A severe post-impact fire consumed the majority of the aircrafts fuselage. The six occupants of the aircraft were fatally injured.

The pilot was qualified, appropriately endorsed and authorised for the operation. The pilots condition and demeanour on the day of the occurrence were reported to be normal.

There was no evidence that fuel contamination, amount of fuel carried, structural failure or meteorological conditions were factors in the occurrence.

The engine installed in the aircraft was different from that specified in the aircraft Type Certificate Data Sheet. Notwithstanding, the Civil Aviation Safety Authority (CASA) and the engine manufacturer reported that the installed engine should have been capable of producing the power output expected from the engine certified for installation in the Cherokee Six. Furthermore, the engine had been in service in the aircraft for 126.2 flight hours with no reported power abnormalities, suggesting that, provided there were no defects, the engine should have been capable of producing the required power throughout its operating range.

The extensive damage caused by the impact forces and post-impact fire prevented functional testing of a significant number of aircraft and engine components. On the available evidence, there was nothing found to suggest what may have degraded the engine performance to the extent reported by the witnesses to the occurrence.

Post-mortem toxicological examination of the pilots blood revealed a blood alcohol concentration (BAC) of 0.081%, the presence of an inactive metabolite of cannabis, and an analgesic preparation consistent with a therapeutic dosage. The possibility that the pilots BAC reading resulted at least in part from post-mortem alcohol production could not be discounted.

There was insufficient evidence to definitively link the pilots prior intake of alcohol and/or cannabis with the occurrence. However, the adverse effects on pilot performance of post-alcohol impairment, recent cannabis use and fatigue could not be discounted as contributory factors to the occurrence. In particular, the possibility that the pilot experienced some degree of spatial disorientation during the turn as a combined result of the manoeuvre, associated head movements and alcohol-induced balance dysfunction could not be discounted.

The following factors were considered to have significantly contributed to the occurrence.

Based on witness reports, the aircrafts engine commenced to operate abnormally shortly after lift off from the runway.
The pilot initiated a steepening right turn at low level.
The aircraft stalled at a height from which the pilot was unable to effect recovery.

The operator has initiated a number of safety actions in order to mitigate some of the issues identified in the report. Those actions include the areas of: company pilot training, fatigue management, documentation, and aircraft operations.

The ATSB has issued four recommendations concurrent with the release of this report. The first three recommendations address the potential use of alcohol and drugs by safety-sensitive personnel in the Australian aviation industry, and options to manage the safety risk to the travelling public of that potential use. The fourth recommendation addresses the CASA Air Operator Certificate Safety Trend Indicator surveillance methodology. In addition, two Safety Advisory Notices have been issued to CASA relating to pilot manipulation of the Cherokee Six fuel selector and development by operators of pilot induction training programs.

Occurrence summary

Investigation number	200204328
Occurrence date	26/09/2002
Location	Hamilton Island, Aero.
State	Queensland
Report release date	18/03/2004
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Piper Aircraft Corp
Model	PA-32
Registration	VH-MAR
Serial number	32-40920
Sector	Piston
Operation type	Charter
Departure point	Hamilton Island, QLD
Destination	Lindeman Island, QLD
Damage	Destroyed

Cessna 210N, VH-RRI

Summary

The pilot, the sole occupant of the Cessna 210 aircraft, was conducting a charter positioning flight from Groote Eylandt to Numbulwar. Witnesses reported that shortly after the aircraft took off from runway 10, it diverged to the right of the runway heading. The aircraft was reported to maintain level flight, at about 20 ft above ground level, and track towards the operator's ticketing office where a company pilot occupied the office, with the door closed, at the time. As the aircraft passed over the office it banked left and adopted a nose-high attitude. The witnesses then saw the aircraft hit a palm tree next to the office, and one saw an object fall from the aircraft. They then saw the aircraft lose altitude and disappear behind buildings. Shortly afterwards, the aircraft was observed on the ground, sliding towards the runway where it came to rest and an intense fire broke out. Although the pilot was able to exit the aircraft unaided, he later died from injuries sustained during the accident. The aircraft was destroyed by impact forces and post-impact fire.

The ticketing office was a converted shipping container situated next to a steel and corrugated iron shelter used as a passenger waiting area. There was a 6.6 m high very high frequency (VHF) aerial attached to the north side of the shelter and two large palm trees immediately south of the office. The office was approximately 150 m south of the runway centreline, 1130 m from the threshold of runway 10 and adjacent to the south-east corner of the sealed aircraft parking area. There was a light pole 5.2 m northeast of the VHF aerial.

The investigation established that the aircraft's left wingtip struck one of the floodlights on the light pole 5.2 m above the ground, detaching the floodlight, the wingtip and the aircraft's strobe light power unit attached to the outer wing rib. The left horizontal stabiliser struck the VHF aerial 5.6 m above the ground. The outer third of the left horizontal stabiliser and the left elevator were detached from the aircraft. A number of palm fronds were also detached from the two palm trees. The relative position of the impact marks indicated that the aircraft was in a left bank and nose-up pitch attitude at the time it struck the floodlight and aerial.

The damaged extremities of the left wing contacted the ground approximately 155 m from the light tower, leaving a shallow ground scar for 21 m before the propeller struck the ground. The aircraft continued to travel across the ground for a further 80 m before coming to rest, upright, within the runway flight strip immediately adjacent to the sealed runway surface. The landing gear and flaps were retracted and all flight control cables were intact and attached. The left wing and cockpit area were destroyed by fire. Ground contact marks and damage to the propeller were consistent with the engine delivering substantial power at impact.

The aircraft had been out of service for 2 months prior to the accident, due to difficulty in obtaining parts to complete a periodic maintenance inspection. The maintenance organisation completed the inspection on 22 March 2002. Although the current maintenance release had been damaged by the fire, there was no indication on the recovered parts of the maintenance release that any defects had been recorded on it. The accident pilot had flown the aircraft from Darwin to Groote Eylandt, via Gove, on the morning of the day before the accident. Another company pilot flew the aircraft on the afternoon of the day before the accident and again on the morning of the accident. The aircraft had completed 5.1 hours time in service since the periodic inspection and neither pilot had reported any aircraft defect that may have contributed to the accident.

The operator had three bases, with the chief pilot and check and training pilot both located at the head office in Darwin. Pilots new to the company were initially based at Groote Eylandt. At the time of the accident, there were three pilots and a base manager on the island. One pilot normally based on Groote Eylandt held the position of senior base pilot and had oversight of operational issues. On the morning of the accident, the senior base pilot had travelled from Groote Eylandt to Darwin. The base manager had oversight of administrative and maintenance issues on the island. The pilot had started flying for the operator on 4 January 2002 and after conducting 2 flights from Darwin, began operating from Groote Eylandt on 8 January 2002.

A check of the pilot's personnel files from his present and previous employers did not reveal any record of him being formally counselled regarding any aspect of his flying. Company personnel described the pilot as reliable and professional in all areas of his duties. Company personnel on the island reported that the pilot apparently slept normally on the night prior to the accident flight and did not exhibit any uncharacteristic behaviour on the day of the accident. Post-mortem and toxicological examination did not identify any factor which may have impaired the pilot's ability to operate the aircraft safely.

At the time of the accident, the automatic weather station at the airport recorded the wind as 9 kts, gusting to 15 kts, from 100 degrees magnetic. Witnesses reported that the weather was generally fine with scattered cloud.

The investigation was unable to establish why the aircraft diverged from the runway heading immediately after take-off.

Occurrence summary

Investigation number	200201100
Occurrence date	24/03/2002
Location	Groote Eylandt, Aero.
State	Northern Territory
Report release date	24/09/2002
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Cessna Aircraft Company
Model	210
Registration	VH-RRI
Serial number	21064628
Sector	Piston
Operation type	Charter
Departure point	Groote Eylandt, NT
Destination	Numbulwar, NT
Damage	Destroyed

Ayres Corp S2R-G10, VH-UDG, Moruya Aerodrome, New South Wales, on 7 January 2002

Summary

The Ayers Turbo Thrush aircraft was conducting water-bombing operations in support of bush fire-fighting activities. Three missions had been flown during the preceding 2 hours, using runway 05. Following the third mission, aircraft operations were suspended, and the aircraft was refuelled. During refuelling the pilot was tasked to drop a load of retardant in another location. The pilot assessed the wind to be from the northeast and lined up for departure on runway 05. The aircraft had a full load of retardant on board. The pilot reported that during the take-off roll he experienced control difficulties, so he jettisoned approximately half of the retardant load in order to assist with directional control of the aircraft. As the aircraft became airborne, it pitched nose-up and rolled right. The right wing collided with a sand dune and the aircraft cartwheeled onto the nearby beach, coming to rest in shallow water. The pilot, who was the sole occupant, egressed the aircraft uninjured. The aircraft was destroyed. A total of 25 minutes had elapsed between the take-off attempt and the preceding landing.

The pilot assessed that while the aircraft was heavy at the commencement of the take-off roll, it was approximately 300 kg below Maximum Take-off Weight. Jettisoning of approximately half the fire retardant load during the take-off roll further reduced the take-off weight.

The Terminal Area Forecast current at the time of the accident indicated a wind of 270 degrees at 15 kts. Recorded and observed meteorological conditions indicated strong gusty north-westerly winds.

The failure of the aircraft to become airborne while under control was consistent with a take-off attempt in a heavy aircraft under the influence of strong tail and crosswind components.

Occurrence summary

Investigation number	200200022
Occurrence date	07/01/2002
Location	Moruya, Aero.
State	New South Wales
Report release date	15/02/2002
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	None

Aircraft details

Manufacturer	Ayres Corporation
Model	S2R
Registration	VH-UDG
Serial number	G10-110DC
Sector	Piston
Operation type	Aerial Work
Departure point	Moruya, NSW
Destination	Moruya, NSW
Damage	Destroyed

Beech Aircraft Corp C90, VH-LQH

Factual Information

FACTUAL INFORMATION

In common with most transport accidents, this occurrence involved a number of different contributing factors. Although some of these factors were associated with actions of individuals or organisations, it is essential to note that the key objective of an ATSB safety investigation is to identify safety deficiencies or weaknesses in the safety system and to learn how to minimise the risk of future accidents. It is not the purpose or intention of the investigation to apportion blame, or to provide a means of determining liability.

Sequence of events

At about 0836 Eastern Standard Time on 27 November 2001, a Beech Aircraft Corporation King Air C90 aircraft, registered VH-LQH, took off from runway 29 at Toowoomba aerodrome, Queensland for an Instrument Flight Rules charter flight to Goondiwindi, Queensland. On board were the pilot and three passengers.

Just prior to, or at about the time the aircraft became airborne, the left engine failed. A subsequent examination of the left engine found that it probably lost thrust-producing power almost immediately. Following the engine failure, the take-off manoeuvre continued and the aircraft became airborne prior to crashing.

The aircraft was equipped with an automatic propeller feathering system, but the propeller was not feathered at impact. The reason the propeller was not feathered could not be determined. The landing gear was not retracted during the short flight. The right engine was developing significant power at impact.

The aircraft remained airborne for about 20 seconds. The aircraft's flight path was typical of an asymmetric, low speed flight situation, and it is unlikely that the aircraft's speed was ever significantly above the minimum control speed (V_mca) of 90 kts. The aircraft manufacturer's specified procedures for responding to an engine failure in LQH stated that the take off should be rejected below the 'take-off speed', specified as 100 kts. After control of the aircraft was lost, and as the aircraft was rolling through about 90 degrees left bank, it struck powerlines about 10 m above ground level and about 560 m beyond the end of the runway. It then continued to roll left and impacted the ground inverted in a steep nose-low attitude. An intense fuel-fed fire erupted upon initial impact with the ground. The aircraft was destroyed and all four occupants sustained fatal injuries. The accident was not considered to be survivable due to the impact forces and post-impact fire.

Maintenance-related issues

The central event in this accident was the failure of the left engine, which was the 'critical' engine on the aircraft in terms of aircraft performance considerations. Examination of the left engine showed internal damage that was consistent with the fracture and release of one or more compressor turbine blades into the engine gas path, resulting in a significant reduction in power from the engine. There were no indications that the engine failure was due to manufacturing defects, metal fatigue, foreign object damage during the flight, or the quality or quantity of fuel on board the aircraft. Examination of the compressor turbine blades indicated that they had been exposed to higher than normal operating temperatures in the period leading up to the accident.

The engine failure occurred at 3,556.0 hours since the last overhaul, which was within the 3,600 hours time between overhaul (TBO) specified in the engine manufacturer's service bulletins. However, the aircraft's engines were operating on a life extension to 5,000 hours TBO in accordance with the provisions of the Australian Civil Aviation Safety Authority (CASA) Airworthiness Directive AD/ENG/5 Amendment 7. A requirement of the AD was that, if the engines were operating to a 5,000 hour TBO, they had to be subject to an engine condition trend monitoring (ECTM) program. The pattern of ECTM data from the left engine indicated that a potentially safety-critical problem existed in that engine for several weeks prior to the accident. For a variety of reasons, that evidence was not detected and analysed, nor was appropriate remedial action initiated. Without timely intervention to address the developing engine problem, it was increasingly probable that the aircraft would have an in-flight emergency involving the left engine.

The pattern of evidence suggested that a problem with the efficiency of the cold section of the engine probably led to temperature-related damage to the compressor turbine blades, which probably resulted in the failure of one of those blades. However, some other explanations for the failure, such as a previous hot start leading to or exacerbating the temperature-related damage, could not be discounted.

Apart from issues associated with the left engine, there was no indication of any fault in any aircraft system that may have contributed to the accident. The ECTM data for the right engine suggested that a potential problem had also been developing in the cold section of that engine for a period of time.

The last maintenance of the left engine most probably occurred on 7 June 2001. Based on the requirements of AD/ENG/5, a compressor performance recovery wash was required to be conducted in response to trend monitoring parameter deviations, or at intervals not to exceed 3 months or 220 hours, whichever came first. Had the performance recovery wash been conducted on the left engine at the appropriate time, it may have been effective in removing the source of deterioration in cold section efficiency.

Prior to March 2001, maintenance on the operator's aircraft was conducted by an external maintenance organisation. From March 2001, maintenance was conducted by a newly formed internal maintenance organisation. The ratio of the operator's available maintenance personnel resources relative to the maintenance resources reasonably required, resulted in the operator's chief engineer experiencing a significant workload. In August 2001, the maintenance controller left the operator and the chief engineer took over the maintenance controller responsibilities. His workload increased significantly when he took on these additional responsibilities.

In addition to the level of maintenance resources, the investigation noted that the defences within the operator's maintenance organisation were deficient in a number of other areas. The chief engineer had minimal preparation for his role as maintenance controller. He had also not completed ECTM training, and therefore the operator arranged to send the data to the engine manufacturer's field representative for analysis. However, the ECTM data were not being recorded or submitted for analysis as frequently as required by the engine manufacturer's requirements or AD/ENG/5. In addition, there were deficiencies in the operator's maintenance scheduling processes.

CASA was aware that the chief engineer had not completed ECTM training and that the operator had an arrangement to send ECTM data to the engine manufacturer's field representative for analysis. However, CASA surveillance had not detected any problems with the operator's ECTM program prior to the accident. Following the accident, CASA inspectors conducted a review of the engine condition monitoring programs of operators in their region. The review found that a number of the operators were not complying with relevant requirements.

The introduction of AD/ENG/5 allowed life extensions to be approved for PT6A engines in Australia under less restrictive circumstances compared with those required by the engine manufacturer. By allowing a wider range of operators to extend TBOs, there was an onus on CASA to take measures to assure itself, during its surveillance activities, that operators were complying with the AD and conducting ECTM appropriately. However, CASA's surveillance system was not sufficiently rigorous to ensure that the mitigators it had introduced within AD/ENG/5 for allowing TBO extensions were effective.

The investigation also noted that the CASA system for approving maintenance organisations and maintenance controllers did not appropriately consider the maintenance organisation's resource requirements.

Flight operations issues

The investigation determined that the pilot was appropriately licensed to conduct the flight, and that it was unlikely that any medical or physiological factor's adversely affected the pilot's performance. There was also no evidence that incorrect aircraft loading or meteorological conditions were factors in the accident.

Several factors would have contributed to the aircraft's speed not being sufficient for the pilot to maintain control of the aircraft during the accident flight. These factors included the significant loss of power from the left engine just prior to, or at about the time, the aircraft became airborne, and the substantial aerodynamic drag resulting from the landing gear remaining extended and the left propeller not being feathered. In addition, the aircraft's speed when it became airborne was probably close to V_mca and not sufficient to allow the aircraft to accelerate to the best one-engine inoperative rate-of-climb speed (V_yse) of 107 kts with an engine failure.

With an engine failure or malfunction near V_mca, the safest course of action would be to reject the takeoff due to the likelihood of the aircraft not being able to accelerate to V_yse. Although in some cases this will mean that the aircraft will overrun the runway and perhaps sustain substantial damage, the consequences associated with such an accident will generally be less serious than a loss of control after becoming airborne.

In this case, the engine failure occurred during a critical phase of flight, in a situation that was among the most difficult for a pilot to respond to in a manner that would ensure a safe outcome. In addition to the timing of the engine failure, a number of factors could have influenced the pilot's decision to continue with the takeoff, including the nature of the operator's procedures, the length of the runway, and the visual appearance of the runway and buildings beyond the runway at the time of the engine failure.

The operator specified a rotation speed of 90 kts, which was less than the 96 kts rotation speed specified by the aircraft manufacturer for King Air C90 aircraft. The operator's specified rotation speed had the effect of degrading the one-engine inoperative performance capability of the aircraft during takeoff. In addition, the operator's procedures did not provide appropriate guidance for pilots regarding decision speeds or decision points to use for an engine failure during takeoff.

While aircraft manufacturers have provided guidance material in operating manuals regarding engine failures leading to power loss in multi-engine aircraft, CASA had not published formal guidance material. The level of training available for emergencies in this category of aircraft during critical phases of flight and at high aircraft weights was less than desirable.

Toowoomba aerodrome was licensed and met the relevant CASA standards. However, runway 29 did not meet the ICAO standard in relation to the runway end safety area (RESA).

Safety action

Since the accident, CASA has made changes to the requirements of AD/ENG/5 and the processes for assessing the suitability of maintenance controllers.

As a result of this investigation, the ATSB issued six recommendations to CASA relating to the following areas:

reviewing operator compliance with the requirements of mandatory turbine engine condition monitoring programs.
surveillance processes for confirming operator compliance with mandatory engine condition monitoring programs.
processes for identifying priority areas for consideration during airworthiness surveillance and approval activities.
processes to assess whether a maintenance organisation has adequate resources to conduct its required activities.
the provision of formal advisory material to operators and pilots about managing engine failures and other emergencies during takeoff.
the assessment of synthetic training devices for the purpose of training pilots in making decisions regarding emergencies during critical stages of flight.

As a result of this accident, the ATSB has issued a recommendation to the aerodrome operator for it to liaise with CASA to evaluate an engineering solution to enhance aircraft deceleration in the runway end safety area of runway 11/29 at Toowoomba aerodrome.

A number of issues identified during the investigation related to the aircraft operator, and would normally have resulted in safety recommendations to that organisation. However, subsequent to the accident the operator ceased operations.

Summary

On 11 November 2005 a further investigation under section 19DF of the Air Navigation Act 1920 was commenced into aspects of this accident. This investigation has been completed and a supplementary report 200507077 has been released and is available on the website.

Occurrence summary

Investigation number	200105618
Occurrence date	27/11/2001
Location	Toowoomba, (ALA)
State	Queensland
Report release date	25/06/2004
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Beech Aircraft Corp
Model	90
Registration	VH-LQH
Serial number	LJ-644
Sector	Turboprop
Operation type	Charter
Departure point	Toowoomba,QLD
Destination	Goondiwindi, QLD
Damage	Destroyed

Avtech Pty Ltd JABIRU ST3, VH-XLX, Southport Aerodrome, on 29 September 2001

Summary

The pilot and his passenger were conducting a private flight in the pilot's Jabiru aircraft in the Southport area. Several other pilots heard the pilot advise over the radio that he was conducting a simulated engine failure and glide approach. The aircraft subsequently impacted a steep embankment short of runway 19 at Southport aerodrome and on the extended runway centreline. The embankment was approximately 2 m high, about 210 m from the displaced approach threshold and 30 m short of the sealed runway surface. Both occupants sustained fatal injuries.

An examination of the wreckage indicated that the aircraft had impacted the embankment in a moderately nose-high, left wing-low attitude. Damage to the propeller indicated that the engine was delivering significant power at the time of impact. There were no known flight control deficiencies, and the evidence indicated that the aircraft was capable of normal flight prior to the accident.

Local procedures required that pilots conduct right circuits when operating on runway 19. Tall trees adjacent to the aerodrome induced localised mechanical turbulence, windshear and downdrafts when the wind was from the southeast. At the time of the accident, the wind was recorded on the Gold Coast Seaway as 150 degrees at 15 kts, gusting to 18 kts.

It is likely that the aircraft entered an area of turbulence and high sink rate generated by the prevailing wind over the adjacent trees. Given the evidence of significant power at the time of impact, it is possible that the pilot had initiated a go around at a stage in the approach from which it was not possible to establish a positive rate of climb.

Occurrence summary

Investigation number	200104707
Occurrence date	29/09/2001
Location	Southport, Aero.
State	Queensland
Report release date	04/12/2001
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Avtech Pty Ltd
Model	ST3
Registration	VH-XLX
Serial number	ST 0011
Sector	Piston
Operation type	Private
Departure point	Southport, QLD
Destination	Southport, QLD
Damage	Destroyed

Agusta 47-G-2A1, VH-SHP

Attachment A

ATTACHMENT A

Mountain wave turbulence

Aviators need to be always aware of the wind and to seek to understand its potential effects and read the environment to appreciate and anticipate its effects on aircraft.

Wind effects around mountains and large features are the result of an interaction between the features, solar heating or cooling, mechanical turbulence caused by obstacles such as trees, and the ambient wind. The effects can be felt as anabatic and katabatic winds (resulting from solar heating and cooling), mountain waves, and rotors or eddies. Mountain waves and rotors are among the more hazardous phenomena aircraft can experience and understanding the dynamics of the wind is important to improving aviation safety.

Encounters with mountain waves can be sudden and catastrophic. Although glider pilots learn to use these mountain waves to their advantage, other aircraft have come to grief. Encounters have been described as similar to hitting a wall. In 1966, a mountain wave ripped apart a BOAC Boeing 707 while it flew near Mt Fuji in Japan. In 1968, a Fairchild F-27B lost parts of its wings and empennage and in 1992, a Douglas DC-8 lost an engine and wingtip in mountain wave encounters. In Australia, mountain waves are commonly experienced over and to the lee of mountain ranges in the southeast of the continent. They also often appear in the strong westerly wind flows Australia's east coast experiences in late winter and early spring.

Mountain waves are the result of flowing air being forced to rise up the windward side of a mountain barrier, then as a result of certain atmospheric conditions, sinking down the leeward side. This `bounce' forms a series of standing waves downstream from the barrier and may extend for hundreds of kilometres; being felt over clear areas of land and open water. Formation of the mountain waves relies on several conditions. The atmosphere is usually stable and an inversion may exist. The wind needs to be blowing almost constantly within 30 degrees of perpendicular to the barrier at a minimum speed of about 20 to 25 knots at the ridgeline. Wind speed needs to also increase uniformly with height and remain in the same direction. Wave `crests' can be upwind or downwind from the range and their amplitude seems to vary with the vertical stability of the flow. The crests of the waves may, (depending on the air having sufficient moisture content), be identified by the formation of lens-shaped or lenticular clouds. Mountain waves may extend into the stratosphere and become more pronounced as height increases with U2 pilots reportedly experiencing mountain waves at 60,000 feet. The vertical airflow component of a standing wave may exceed 8,000 feet per minute.

Rotors, or eddies can also be found embedded in mountain waves. Formation of rotors can also occur as a result of down slope winds. Their formation usually occurs where wind speeds change in a wave or where friction slows the wind near to the ground. Often these rotors will be experienced as gusts or windshear. Clouds may also form within a rotor.

Many dangers lie in the effects of mountain waves and rotors on aircraft performance and control. In addition to generating turbulence that has demonstrated sufficient ferocity to significantly damage aircraft or lead to loss of aircraft control, the more prevailing danger to aircraft in the lower levels in Australia seems to be the effect on an aircraft's climb rate. General aviation aircraft rarely have performance capability sufficient to enable the pilot to overcome the effects of a severe downdraft generated by a mountain wave, or the turbulence or windshear generated by a rotor. In 1996, three people were fatally injured when a Cessna 206 encountered lee (mountain) waves. The investigation report concluded that, "It is probable that the maximum climb performance of the aircraft was not capable of overcoming the strong downdrafts in the area at the time."

Crossing a barrier into wind also means that an aircraft's groundspeed would be reduced, remaining in an area of downdraft for longer. Flying downwind would likely put the aircraft in updraft as it approached rising ground. Rotors and turbulence may also affect low level flying operations near hills or even trees. In 1999, a Kawasaki KH-4 hit the surface of a lake during spraying operations at 30 feet. The lack of sufficient height to overcome the effects of wind eddies and turbulence was implicated as a factor involved in the accident.

Research into mountain waves and rotors or eddies continues but there is no doubt that pilots need to be aware of the phenomenon and take appropriate precautions. Although mountain wave activity is normally forecast, many local factors may effect the formation of rotors and eddies. When planning a flight, the pilot needs to take note of the winds and the terrain to assess the likelihood of waves and rotors. There may be telltale signs in flight, including the formation of clouds (provided there is sufficient humidity to provide for cloud formation) and disturbances on water or wheat fields. Some considerations include allowing for the possibility of significant variations in the aircraft's altitude if up and downdraughts are encountered. A margin of at least the height of the hill or mountain from the surface should be allowed. Ultimately, it may be preferable for pilots to consider diverting or not flying, rather than risk flying near or over mountainous terrain in strong wind conditions conducive to mountain waves and rotors.

Summary

The Agusta/Bell 47G-2A1 helicopter departed from Maroochydore airport at about 1420 Eastern Standard Time (EST) on a solo navigation exercise. The pilot intended to track via Somerset Dam, Kenilworth, Nambour and return to Maroochydore under the Visual Flight Rules (VFR), with an expected enroute flight time of about 1.9 hours. A flight plan was not submitted to Airservices Australia by the pilot. However, a flight notification form was retained by the company for search and rescue (SAR) purposes. Shortly before take-off, the pilot was cleared by the Maroochydore Tower controller to track direct to Somerset Dam via The Big Pineapple initially at 1,500 ft above mean sea level (AMSL).

Air Traffic Services (ATS) primary radar intermittently tracked the helicopter at a position 7 NM northeast of the accident location about 40 minutes after departure. The primary "paint" ceased about that time and location. A witness reported seeing the helicopter near the northern side of Mount Archer at about 1515 EST and flying in a manner consistent with the pilot experiencing controllability difficulties. A subsequent aerial search located the wreckage at a position about 1 NM right of the direct track from Maroochydore to Somerset Dam and on the north-north-eastern slope of Mount Archer. The helicopter sustained severe impact damage. The pilot received fatal injuries.

Some notes containing pre-flight navigation planning calculations and small pieces of the perspex cockpit bubble were found several hundred metres before the accident site. The notes contained navigation calculations that did not take into account the forecast enroute winds. Personnel at the flight training school did not recall discussing at length the forecast weather conditions with the pilot and, in particular, they did not recall briefing the pilot about the forecast mountain waves prior to the navigation exercise. The personnel at the flight training school also reported that helicopter pilots had been flying throughout the day in the Maroochydore region without experiencing any controllability difficulties induced by the forecast and actual strong winds.

The ATSB investigation team did not attend the accident site but viewed video footage and police photographs of the wreckage. The video footage had been recorded by the search and rescue helicopter crew at the time the wreckage was located. Damage to the helicopter structure was extensive and the tail boom was severed. According to the search and rescue helicopter crew, the helicopter's emergency locator transmitter (ELT) did not activate. The pilot also carried a portable ELT but it was damaged during the impact and did not activate.

The pilot held a Student Pilot Licence and a Restricted Private Pilot (Aeroplane) Licence. At the time of the accident the pilot had accumulated a total of 72.5 flying hours in helicopters, including 21.5 hours on Bell 47G helicopters. The pilot's aeroplane flight time records were not available to the investigation.

At the time the accident report was compiled, the pilot toxicology and autopsy results were not available. Consequently, the investigation was unable to comment on whether the pilot's performance was adversely affected by any pre-existing physiological condition.

There were no known maintenance deficiencies and the helicopter was considered capable of normal flight prior to the accident.

A Bureau of Meteorology (BOM) area forecast, issued at 1338 EST on the day of the accident, indicated isolated severe turbulence and mountain waves below 9,000 ft. The BOM examination of the available data indicated that the wind between 1,000 ft and 5,000 ft above ground level (AGL) in the Mount Archer area was constant with height at about 250 degrees True in the range 25 to 30 kts. The surface wind speed was estimated to be around 15 to 20 kts with frequent gusts in the range 25 to 30 kts. The relative orientation of the ridge and wind direction were conducive to mountain waves and possible rotor effects (see Attachment A) to the northeast of Mount Archer. The helicopter impacted terrain on the north-north-eastern slope of Mount Archer. The search and rescue helicopter pilot's report of actual meteorological conditions in the vicinity of the accident site was consistent with the BOM forecast.

Initial video and photographic evidence indicated that the helicopter probably encountered severe turbulence from mountain waves or rotors in flight while approaching the lee of Mount Archer. The evidence suggested that the main rotor blades may have severed the tailboom approximately 1 m forward of the tail rotor assembly. This accident signature is consistent with excessive blade flapping. The evidence indicated that a divergence of the main rotor blade from its normal plane of rotation probably occurred as a result of severe turbulence generated by mountain wave or rotor activity, and a main rotor blade contact with the tailboom and cockpit area ensued, resulting in a loss of control of the helicopter.

It is also possible that the collective lever friction may have been overcome by the severe turbulence that caused the non-powered collective lever to suddenly drop. The collective lever drop would have induced a sudden nose down attitude and this may have caught the pilot by surprise. The pilot may have instinctively and rapidly applied aft cyclic to correct the aircraft's attitude. The rapid application of aft cyclic in this situation may have been sufficient to induce main rotor blade contact with the tailboom.

A further discussion of mountain wave phenomena is provided in Attachment A.

Occurrence summary

Investigation number	200104092
Occurrence date	29/08/2001
Location	Mount Archer
State	Queensland
Report release date	20/12/2001
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Agusta, S.p.A, Construzioni Aeronautiche
Model	47
Registration	VH-SHP
Serial number	80431
Sector	Helicopter
Operation type	Flying Training
Departure point	Maroochydore, QLD
Destination	Maroochydore, QLD
Damage	Destroyed

Beech Aircraft Corp C24R, VH-BMQ

Significant Factors

The aircraft's engine was not operating normally throughout the take-off run.
The pilot continued the take-off run with a 'rough running' engine.

Analysis

Based on witness evidence and the on-site examination of the aircraft, the investigation determined that the engine was not functioning normally during the take-off. However, the prospects of being able to positively identify conditions that may have affected the operation of the engine, the fuel and ignition systems, were severely reduced by the extent of the fire damage. Had the aircraft performed as predicted by the Pilot's Operating Handbook, it should have attained a height of more than 250 ft above ground level at the point that it contacted the trees beyond the end of the airstrip.

It was not possible to determine to what extent the incorrect spark plugs had contributed to the accident as the aircraft had flown with no reported problems from Hoxton Park to Trilby station. However, as indicated by the engine and spark plug manufacturers, the use of incorrect heat range spark plugs could result in serious engine damage from possible detonation/ pre-ignition. The reported symptoms such as engine 'rough running' and 'backfiring' are consistent with a pre-ignition condition.

The investigation could not determine why the pilot in command elected to continue the take-off with a 'rough running' engine.

Summary

The Beech C24R Sierra aircraft had been flown to Trilby Station as part of a weekend pleasure trip two days before the accident. The three occupants, including the aircraft owner, were qualified pilots experienced on the aircraft type.

The aircraft owner was the pilot in command for the flight from Hoxton Park to Trilby Station. During their stay at the property, none of the occupants of the aircraft had given any indication that there had been any problems regarding the operation of the aircraft on that flight.

For the return flight, the youngest of the three men was designated as pilot in command. Witnesses indicated that he occupied the front left seat of the aircraft. He was appropriately licenced for the aircraft type and held a current medical certificate. The aircraft owner occupied a rear seat while the other pilot occupied the front right seat.

Witnesses reported that the engine was 'running roughly' and 'missing' shortly after startup. One witness recalled the pilot carrying out a pre-takeoff engine run-up. The aircraft was then observed to taxy to the end of the dirt strip where the pilot immediately commenced the take-off run. Throughout the take-off run, the aircraft appeared to accelerate slowly with reported 'frequent backfires' and the engine 'missing badly'. One witness expected the pilot to reject the take-off. None of the witnesses observed the aircraft become airborne. Several seconds later the engine noise ceased, followed by the sound of an impact. The burning wreckage of the aircraft was subsequently located on the western bank of the Darling River.

The Bureau of Meteorology assessed the weather conditions at Trilby Station around the time of the accident as fine, with a temperature of 18 degrees C, and the wind from the NW at 15 knots. Calculations based on this data indicated that during the take-off there would have been approximately 5 knots headwind component, and 14 knots crosswind from the right. This was confirmed by witness observations.

The airstrip was 1000 m long and 30 m wide, with a level, dry, gravel surface. There were several small trees 108 m beyond the end of the strip on the extended centreline and a cleared area to the right.

The Pilot's Operating Handbook for the aircraft indicated that with 15 degrees of flap selected, a maximum take-off weight of 2750 lbs, a 5 kt headwind, temperature of 18 degrees C, and 350 ft elevation above mean sea level, the take-off distance to an obstacle height of 15 m (50 ft) was predicted to be 503 m (1650 ft). The trees struck by the aircraft were 1108 m (3635 ft) from the downwind end of the strip.

Autopsy and toxicological examinations of the pilot in command did not reveal any pre-existing medical condition that would have prevented him from safely operating the aircraft.

Inspection of the area between the end of the strip and the accident site revealed that, after becoming airborne and while in a left-wing low attitude, the aircraft had struck the tops of several small trees located beyond the end of the airstrip. The aircraft then crossed the Darling River, impacting on the steeply sloping western bank. Fire had destroyed most of the aircraft structure, except the aircraft's empennage, engine and propeller, limiting the amount of useful information available to the investigation.

Examination of the flap system indicated that the flaps were positioned at approximately 15 degrees. The landing gear position could not be determined. The airframe fuel system was destroyed in the fire. Both fuel tank caps were located secured to their fuel tank filler necks and the fuel selector position was not able to be determined.

The propeller blades were found in a fine pitch position. Fire damage to the propeller governor precluded an assessment being made regarding its pre-impact serviceability. The nature of the damage to the propeller blades indicated that they were not rotating under power on impact. The severe heat damage to the engine's ignition system and fuel control system prevented an assessment being made of their pre-accident operation.

The engine and propeller were removed from the wreckage for a technical examination at an appropriate overhaul facility. This examination revealed spalling damage on the number 1 cylinder exhaust valve camshaft follower. The number 1 cylinder inlet valve stem tip was 'belled' out. The number 4 cylinder connecting rod gudgeon pin bushing was a loose fit in the rod small end. However, nothing significant was noted during the examination of the core engine that would have prevented its operation.

The spark plugs fitted to the engine were part number REM38E in all cylinder lower plug positions, and part number REM40E in all upper positions. Due to the engine being found inverted at the accident site, most of the spark plugs had been coated with engine oil. When tested, all spark plugs operated normally, with the exception of the number 4 cylinder lower plug. After it had been cleaned, the spark plug again operated normally.

The engine manufacturer listed the spark plugs approved for use in their various model engines, and advised that only the approved plugs were to be fitted. The REM38E plugs were the correct type for the engine. The REM40E plugs were of a higher heat range for use in engines of a lower compression ratio. They were neither recommended nor approved for this engine model. The manufacturer stated that during the certification of the engines and spark plug approval, it was determined that it was possible to experience detonation/pre-ignition and serious engine damage with other than the approved spark plugs fitted. The engine manufacturer further advised that the mixing of spark plugs by heat range was not good practice.

The spark plug manufacturer described detonation as the explosion of unburnt fuel ahead of the normal flame front, and is typified by a mildly rough running engine with an audible knocking sound. Pre-ignition is the ignition of the fuel while the compression stroke is occurring, but much earlier than intended. Pre-ignition is typified by engine roughness and backfiring.

The only aircraft documents located were the engine and aircraft radio maintenance logbooks, and some expired maintenance releases. The aircraft and propeller logs, along with the current maintenance release, were believed to have been destroyed in the post-accident fire.

The aircraft's Lycoming IO-360-A1B6 engine, serial number L-7866-51A, had been installed in the aircraft on 29 November 2000 following overhaul. The engine had approximately 35 hours in service since installation. Documentation indicated that during the overhaul, amongst other components, all of the camshaft followers and the spark plugs were replaced. Only REM38E spark plugs were listed as fitted. No documentation indicating fitment of REM40E spark plugs was found. The engine logbook indicated that, on 22 February 2001, the fuel control unit was recalibrated, and the fuel injector nozzles tested due to high fuel flow at take-off. The logbooks indicated that during a subsequent engine run, the engine operated normally.

A pilot who flew the aircraft on 17 May 2001 reported that, following take-off, he experienced an engine surge similar to a change of propeller pitch towards coarse. After an adjustment of the propeller pitch control the engine returned to normal. He recorded the problem and mentioned it to the aircraft owner, who indicated he would have the propeller system examined. No maintenance records relating to this event were located. Maintenance documentation available indicated that the propeller governor had been repaired on 8 September 2000, and the propeller had been repaired on 12 October 2000.

Witnesses reported that the aircraft had been refuelled from a sealed drum on the afternoon of the day before the accident. Post accident examination of a sample of fuel remaining in the drum showed it to be free of water contamination. A detailed analysis of the fuel, carried out by a National Association of Testing Authorities (NATA) accredited laboratory, showed that it met the requirements of 100 Low Lead Avgas. Witnesses indicated that a fuel drain check was carried out prior to flight.

Occurrence summary

Investigation number	200102289
Occurrence date	27/05/2001
Location	20 km W Louth
State	New South Wales
Report release date	08/10/2002
Report status	Final
Investigation type	Occurrence Investigation
Investigation status	Completed
Mode of transport	Aviation
Aviation occurrence category	Collision with terrain
Occurrence class	Accident
Highest injury level	Fatal

Aircraft details

Manufacturer	Beech Aircraft Corp
Model	24
Registration	VH-BMQ
Serial number	MC-558
Sector	Piston
Operation type	Private
Departure point	Trilby Station, NSW
Destination	Hoxton Park, NSW
Damage	Destroyed

Subscribe to Collision with terrain

Collision with terrain

Summary

Analysis

Safety Action

Local safety action

ATSB safety action

Recommendation R20030219

Recommendation R20030220

Recommendation R20030221

Occurrence summary

Aircraft details

Summary

Occurrence summary

Aircraft details

Significant Factors

Analysis

Factual Information

History of the flight

Injuries to persons

Wreckage and impact information

Personnel Information

Landing area

Previous occurrence at the airstrip

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Occurrence summary

Aircraft details

Summary

Occurrence summary

Aircraft details

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Occurrence summary

Aircraft details

Summary

Occurrence summary

Aircraft details

Factual Information

FACTUAL INFORMATION

Sequence of events

Maintenance-related issues

Flight operations issues

Safety action

Summary

Occurrence summary

Aircraft details

Summary

Occurrence summary

Aircraft details

Attachment A

ATTACHMENT A

Mountain wave turbulence

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Aircraft details

Significant Factors

Analysis

Summary

Occurrence summary

Aircraft details