Skip to main content

Collision with terrain

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.

Further Reading:

Bureau of Meteorology. (1988). Manual of meteorology part 2: Aviation meteorology. Canberra, ACT: Australian Government Publishing Service.

Bureau of Meteorology. (1991, September). Downslope winds are dangerous. BASI Journal, 9, 38-39.

Jorgensen, K. (undated). Mountain flying: A guide to helicopter flying in mountainous and high altitude areas. Westcourt, QLD: Cranford Publications.

Lester, P. F. (1993). Turbulence: A new perspective for pilots. Englewood, CO: Jeppesen Sanderson.

Welch, John, F. (Ed.). (1995). Van Sickles modern airmanship (7th Ed). New York, NY: McGraw-Hill.

Woods, R. H., & Sweginnis, R. W. (1995). Aircraft accident investigation. Casper, WY: Endeavor Books.

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

  1. The aircraft's engine was not operating normally throughout the take-off run.
  2. 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

Piper PA-30, VH-CNZ

Significant Factors

  1. The left-wing fuel tank filler caps were not secured before take-off.
  2. Fuel vented from the left-wing fuel tanks and had the appearance of smoke coming from the left engine.
  3. The pilot(s) did not take the appropriate actions to maintain aircraft performance after shutting down the left engine.
  4. The pilot(s) were unable to maintain control of the aircraft.

Analysis

The aircraft took off with the fuel caps for the left-wing tanks not secured, and the flap covers unlocked. It could not be established if the flap covers remained in the opened (up) position where they were left by the refueller, or whether they moved to the closed/not locked position because of aircraft movement or vibration, or airflow.

There may have been some perceived time pressure regarding the pre-flight inspection because of the deteriorating light. Further, the light may have reduced the visual prominence of the open flap covers. Either, or both of those influences could have contributed to the pilots not being aware that the left-wing fuel caps were not secured.

As the aircraft accelerated during the take-off roll, the caps fell from the left-wing filler ports, probably as a result of vibration and/or aerodynamic forces. The 'smoke' observed by the tower controller and a witness was fuel venting from the open tank filler ports. It was unlikely that any other interpretation of the venting fuel would reasonably have been made in the circumstances, particularly in the deteriorating ambient light conditions, coupled with the position of the filler ports on either side of the engine nacelle.

Other than the tower controller's transmission regarding the 'smoke', it could not be determined what other information the pilots of the aircraft used in reaching the decisions to shut down the left engine and attempt a left turnback. However, based on the examination of the left engine and propeller, there would most probably have been no indication from the cockpit instruments that the left engine was malfunctioning in any way. Whether the pilots were able to observe the 'smoke', or became aware of the situation regarding the fuel caps, could not be determined.

It was apparent from the record of communications with the control tower that the pilot who initiated communications with the air traffic controller prior to take off was not the same person who communicated with the tower controller following the advice that there was 'smoke' coming from the left engine. However, which pilot manipulated the aircraft controls during that period could not be determined.

At the time the aircraft passed abeam the control tower, there was adequate runway and overrun distance available for the aircraft to land and decelerate significantly before reaching the boundary fence. Whether the pilots considered the option of landing straight ahead after being notified of the 'smoke' could not be determined.

The flight path taken by the aircraft (the turn away from the live engine) and the aircraft configuration at impact (left propeller not feathered, landing gear extended) indicated that aspects critical to maintaining single engine performance were not accomplished. The final flight path and impact attitude of the aircraft were typical of what might be expected following loss of control when the airspeed falls below the minimum single engine control speed.

Summary

Sequence of events

The co-owners of the Piper Twin Comanche aircraft, both of whom were pilots, were conducting the flight to test a newly fitted left propeller governor.

At about 1650 EST, one of the owners telephoned the aircraft refueller and requested fuel for VH-CNZ. When the refueller arrived at the aircraft a short time later, he was requested by the other pilot to refuel the aircraft to full tanks. The refueller reported that this pilot appeared to be conducting a preflight check of the aircraft while the other pilot was seated in the cockpit, possibly in the left seat. The refueller noticed that the fuel filler flap covers were open and that the fuel tank filler caps, two on each wing, one on either side of the engine nacelles, had each been removed and placed on the wing adjacent to the filler points. After adding fuel to the right auxiliary fuel tank, the refueller placed the cap in the filler port. The pilot who was doing the external inspection approached him and said that he would secure the caps because they had a locking mechanism that was different from those fitted to many other aircraft types. The refueller then filled the right main tank and placed the cap in the filler port. As he moved away, he saw the pilot move to the tank. The refueller then moved to the left side of the aircraft and filled the left auxiliary and left main tanks, again placing the caps in the filler port of each tank. He did not secure the caps and left the flap covers open. At this stage, he saw the pilot lying beneath the fuselage, apparently conducting a fuel drain check. The refueller recorded in the refuelling register that 179 litres of fuel had been added to the aircraft at 1700. He then told the pilot seated in the aircraft the amount of fuel he had added, and reminded her that he had not secured the fuel caps. The refueller then moved to refuel another aircraft.

A short time later, the aircraft taxied for take-off. Visual meteorological conditions existed with scattered light cloud at 3500 feet. The wind was from the southeast, gusting to 5 knots. Sunset on the day of the accident was at 1658. At the time of the accident, the sun was 3.5 degrees below the horizon, bearing 292 degrees True.

The following is a summary of the pertinent communications between the aircraft (CNZ) and Archerfield Tower (Tower), which commenced at 1714.14.

  • 1714.14 (CNZ) Archer Tower Twin Comanche Charlie November Zulu is ready runway 10 right departing to the southeast (male voice).
  • 1714.26 (Tower) Charlie November Zulu Tower runway right cleared for take-off.
  • 1714.31 (CNZ) Runway right cleared for take-off Charlie November Zulu (male voice)
  • 1715.21 (Tower) Charlie November Zulu there is smoke coming from one of your engines (pause) it's the left engine.
  • 1715.31 (Tower) Charlie November Zulu did you copy.
  • 1715.36 (CNZ) Charlie November Zulu affirm we're shutting it down and request a left turn back for landing (female voice).
  • 1715.43 (Tower) Charlie November Zulu left turn approved.
  • 1715.45 (CNZ) Charlie November Zulu (female voice).
  • 1716.23 (Tower) Charlie November Zulu clear to land.
  • 1716.27 (CNZ) Clear to land Charlie November Zulu (female voice).

Several witnesses observed the progress of the aircraft. Their observations confirmed that a cloud of what appeared to be 'greyish black smoke' coming from both sides of the left engine. The aircraft yawed sharply left and right just after becoming airborne and then commenced a left circuit at very low level, estimated to have been 100 ft above ground level. The landing gear remained extended throughout the circuit. Approaching the western boundary of the airport, the aircraft entered another left turn, passing low over some buildings. Part way through the turn, the aircraft's angle of bank suddenly increased and it descended rapidly into the ground. Both occupants were fatally injured.

Wreckage and impact information

Initial examination at the accident site revealed that the fuel filler flap covers of the two left wing tanks were open, and both filler caps were missing. The caps were recovered the following day from runway 10 right and the adjoining clear way. Fuel wetting was evident on the ground below the open fuel caps of the inverted left wing. A total of approximately 35 litres of fuel was recovered from the damaged right wing fuel tanks. The recovered fuel was confirmed as the correct type and grade for the aircraft. The accident aircraft was the thirteenth of sixteen refuelled from the same batch and tanker on the day. The records show that the fuelling agent had sample tested the fuel on three previous occasions throughout the day. Given that there were no reports of fuel related problems from any other aircraft and because of the obvious level of performance from the right engine. The quality of the fuel as a factor in the development of the accident was discounted.

The aircraft wreckage was located in an open area adjacent to the western boundary fence of the aerodrome, approximately 250 metres north-northwest of the threshold of runway 10 left. Impact marks indicated that the aircraft was inverted and rolling left when it struck the ground. The aircraft attitude was 55 - 60 degrees nose down and 25 - 30 degrees left wing low. The main wreckage came to rest about 17 m beyond the initial impact point. The tail section was right way up and the main wing section was folded back on top of the rear fuselage. The cabin area was severely distorted, with the instrument panel and cockpit floor displaced rearward.

Specific points noted during the wreckage examination included the following:

  • There was no evidence of either pre-impact or post impact fire including to the left engine. (PA30-160 aircraft, along with most other light twin engine aircraft, were not equipped with fire detection or suppressant systems.)
  • The landing gear was locked in the extended position and the wing flaps were fully retracted. Impact damage prevented the serviceability of the stall warning system being assessed.
  • The nature and extent of damage to the cockpit engine control pedestal prevented any useful witness mark information being obtained regarding the pre-impact position of the controls.
  • Ground contact marks and the condition of the right propeller blades indicated that the right engine was developing significant power at impact. Ground contact marks and the condition of the left propeller blades indicated that the left propeller was rotating at impact but that the engine was not developing power.

The constant speed governor from the left engine was recovered; the only obvious damage being slight bending to the control-input shaft which was consistent with impact damage. The governor was functionally tested at an approved overhaul facility. The tests met all the manufacturer's specifications, with the exception of the maximum RPM setting that indicated 2285. This was 45 RPM below the specification. Specialist opinion was that this discrepancy could be attributed to the damage to the control-input shaft.

Disassembly of the left and right propellers found no evidence of any pre-existing fault or defect. Disassembly of the left propeller confirmed the blades were at fine pitch and not in the feathered position at impact. Disassembly of both engines did not reveal any pre-existing fault or defect that would have affected normal engine operation.

Fuel tank filler points

The two fuel tank filler points on each wing were located on either side of the engine nacelles. The filler points consisted of filler port, a cap to seal the port, and a flap covering the cap access. The cap consisted of a black rubber insert that compressed to seal the fuel filler tank port by the action of a screw grip on top of the cap. The flap cover was secured with a winged slotted 'dzus' type fastener and, when locked, was flush with the upper surface of the wing. Locking the flap cover required deliberate action, and could not be achieved by slamming the cover down. The flap covers were hinged parallel to the longitudinal axis of the aircraft, and opened away from the engine nacelles. The slotted 'dzus' fasteners had to be locked for the flap covers to be closed flush with the wing surface. If not locked, the flap covers would stand slightly proud of the wing surface.

The left and right wing filler points, inboard of the engine nacelles, were visible from the left and right cockpit seats, respectively. They may have been visible in the pilot's peripheral vision, depending on the pilot's seating position. With the flap covers open, there was a high level of contrast between the white painted upper surface of the wing and the dark underside of the flap covers and filler cavity. In reduced light conditions, the level of contrast would have been lower.

When in the open position, the outboard flap covers were partly visible from the cockpit. If those covers were down, but not locked, they were not visible from the cockpit.

The 'dzus' fastener locking mechanism for the flap covers on the left-wing tanks functioned normally. Aside from damage caused to one cap when it was struck by an aerodrome mower operating on the runway 10R flight strip on the morning following the accident, both fuel caps from the left-wing tanks were in a serviceable condition.

The pilots

Both pilots were appropriately licensed and held current medical certificates.

Toxicological and Post-mortem analysis did not reveal the presence of any compound or pre-existing medical condition that may have affected the performance of either pilot.

Aerodrome information

Runway 10 Right was 1100 m long. Beyond the runway end was a flat area extending for more than 400 m, and free of major obstacles, to the aerodrome boundary fence. The distance from a position on the runway abeam the control tower to the boundary fence was about 800 m.

The control tower cab was 65 ft above ground level. The controller reported that when the aircraft passed abeam the tower, its level appeared to be slightly below that of the tower cab. With respect to the control tower, the remaining light or glow from the sun was behind and slightly left of the position of the aircraft, as it became airborne.

Aircraft performance

The aircraft flight manual performance charts indicated that, in the prevailing conditions, the take-off ground run distance required was about 350 m, depending on the flap setting used. The observations of the tower controller indicated that the actual take-off performance of the aircraft was not substantially different from that figure.

The landing distance over a 50-ft obstacle was approximately 500 m, depending on the aircraft flap setting and approach speed.

Single engine performance

The sea level single engine climb performance of light twin engine aeroplanes certified in accordance with United States Federal Aviation Regulation 23 requirements can be up to 70 to 90 percent less than the twin engine performance. Many factors can contribute to this performance loss such as aircraft age and condition, leaving the landing gear extended, not feathering a propeller, not maintaining the correct airspeed, and not turning towards the live engine.

The Pilot's Operating Manual for the aircraft included information on propeller feathering procedures and single engine flight. That information included the statement that, when climbing with one engine inoperative, the landing gear and wing flaps must be retracted.

Occurrence summary

Investigation number 200102253
Occurrence date 23/05/2001
Location Archerfield, Aero.
State Queensland
Report release date 04/11/2002
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 Piper Aircraft Corp
Model PA-30
Registration VH-CNZ
Serial number 30-858
Sector Piston
Operation type Private
Departure point Archerfield, QLD
Destination Archerfield, QLD
Damage Destroyed

Cessna 402, VH-RJH

Summary

The owner/pilot of the Cessna 402 was conducting a check circuit following the installation of a repaired engine-driven fuel pump. He occupied the left control seat. The intended lessee, who was also a pilot, occupied the right control seat.

A witness observed the aircraft fly downwind on a left circuit for runway 18 and complete what appeared to be a normal base turn. When the aircraft was on final approach, with the landing gear extended, it briefly pitched nose up and yawed left before the nose pitched down and the yaw was corrected. The aircraft then rapidly lost altitude and crashed into scrub short of the airport boundary fence and approximately 200 m from the runway threshold. Both occupants sustained serious injuries. The intended lessee later indicated that both engines had ceased operating almost simultaneously when the aircraft was on final approach. He said that he then moved both fuel selectors from main tanks to auxiliary tanks.

The aircraft was examined shortly after the accident. Very little fuel remained in any of the four fuel tanks. Three days later, after the aircraft was removed to a maintenance facility, the fuel tanks were drained. The amount of fuel recovered from each tank was measured as follows:

Left main: 2.50 US gallons / 9.5 litres
Left auxiliary: 2.75 US gallons / 10.45 litres
Right auxiliary: 3.0 US gallons / 11.4 litres
Right main: 1.25 US gallons / 4.75 litres

Total 9.5 US gallons / 36.1 litres

The aircraft was equipped with optional 20 US gallon auxiliary fuel tanks. The Cessna 402 Pilot's Operating Handbook stated that the total unusable fuel for this configuration was 3 US gallons, consisting of 1 US gallon in each main tank, and 0.5 US gallons in each auxiliary tank.

Both engine-driven fuel pumps were removed for testing. They functioned correctly. The engine-driven fuel pump from the left engine had been re-installed the day before the accident after being repaired. During subsequent engine ground runs, maintenance personnel noted that the fuel gauges indicated less than 5 US gallons in each main tank. Although there was a small amount of usable fuel recovered from the main tanks, it is possible that aircraft attitude changes during the approach allowed the relatively small amount of fuel remaining to move away from the fuel pick-up points inside the main tanks, thereby starving the engines of fuel.

No documentary or witness information was found to suggest that the aircraft had been refuelled after the engine runs were completed, and prior to conducting the check circuit. Two witnesses stated that

Occurrence summary

Investigation number 200102216
Occurrence date 18/05/2001
Location Maroochydore/Sunshine Coast, Aero.
State Queensland
Report release date 24/06/2002
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 Serious

Aircraft details

Manufacturer Cessna Aircraft Company
Model 402
Registration VH-RJH
Serial number 4020023
Sector Piston
Operation type Private
Departure point Maroochydore, QLD
Destination Maroochydore, QLD
Damage Substantial

Grob G-115C2, VH-BGQ

Safety Action

Local safety action

As a result of the investigation, the operator conducted a review of night training operations together with an assessment of their aerodrome emergency plan. As a result of these reviews, the following actions were completed:

  1. The purchase of portable runway lighting;
  2. The purchase of additional emergency equipment;
  3. The review of the aerodrome emergency plan;
  4. The construction of an observation deck for instructors to monitor solo flying operations;
  5. The review and amendment of the training syllabus to include an introduction to night flying, scheduling students to complete instrument flying training (including night synthetic training) before introducing the night flying component;
  6. The discontinuation of the practice where night flying is scheduled concurrently with other training sequences;
  7. The introduction of a requirement for instructors to more closely monitor student duty times; and
  8. The introduction of human factors training (night flying), prior to the commencement of night flying training.

Analysis

The circumstances of the accident were consistent with the student becoming disorientated after take-off, possibly associated with the change in aircraft configuration during completion of the after take-off checklist.

The student was in the early phase of his night flying training and, although he reported that an unserviceable attitude indicator had contributed to his disorientation, he had only limited instrument flying experience. He had not completed the training required in the operator's syllabus prior to commencing night flying and, most probably, had not developed his instrument flying skills to the standard normally required for this stage of training.

The dual check immediately before the accident flight had been conducted only a short time after last light and possibly, when there was still some external visual reference available.

Although the student received a short rest break before commencing the accident flight, he had been in attendance at the aerodrome for most of the day and recently had returned from an extended navigation exercise. Accordingly, it is possible that fatigue had also affected the student's performance and his ability to maintain control of the aircraft with reference to the flight instruments.

Summary

The student pilot of a Grob 115 C aircraft was authorised by his instructor to conduct solo night circuits at Merredin, WA. Shortly after take-off from runway 28, and as the student commenced his after take-off checks (at about 300 ft AGL, including flap retraction and engine power reduction), he noticed that the aircraft was becoming difficult to control. As he scanned the aircraft's flight instruments he decided that the attitude indicator was unreliable and noted the directional indicator turning quickly to the left. Control inputs applied to reduce the rate of turn were unsuccessful. The student recalled that the airspeed indicator was indicating 140 kts.

The student reported that despite applying back-pressure to the control column and maintaining the pitch attitude for a climb, the aircraft continued to descend and impacted the ground beyond the aerodrome boundary. Immediately following the ground impact, the aircraft became airborne and the student recalled applying full power and commencing a climb. An instructor on the ground established radio communication and provided instructions to assist the student. The student stated that the attitude indicator remained unreliable for the entire circuit but, with the instructor's assistance, he was able to complete a normal approach and landing. As the nose was lowered to the runway during the landing roll, the propeller struck the runway and stopped. The accident occurred at approximately 2000 Western Standard Time. The student was not injured and vacated the aircraft without assistance.

Examination of the aircraft indicated that the nose wheel and oleo had been damaged during the initial impact with the ground and had detached from the aircraft prior to landing. The nose oleo was subsequently recovered from a paddock in the vicinity of a left base position for runway 28.

Last light at Merredin on the night of the accident was 1802. It was reported to be a dark night, with no discernible natural horizon. During the initial climb from runway 28, the student had no significant external visual reference available and was using the flight instruments to maintain control of the aircraft.

Following the accident, the operator contracted an independent maintenance organisation to examine the aircraft flight instruments, engine driven vacuum pump, and other associated systems. No pre-accident defect was detected.

The flying roster for the day indicated that the student was scheduled to complete two separate exercises, a navigation phase check during the afternoon, followed by solo night circuits. The student had arrived at the aerodrome at 1000 to prepare for his phase check.

A delay in departure time for the phase check meant the aircraft arrived back at Merredin after last light. Prior to concluding the phase check, the instructor completed three circuits with the student for the purpose of authorising his solo night flying. The total flight time for the phase check was recorded as 3.3 hours, of which 0.2 hours was logged at night. By 1845, all tasks associated with the phase check were completed and the student took a short meal break before recommencing duty for the night circuits.

The operator had a detailed flying training syllabus for the conduct of training. It was reported that a gap in the flying program had permitted some students to progress through their training at an accelerated rate, which introduced night flying at an earlier stage of training than was usual. The student had been previously assessed proficient in the required syllabus items for solo night circuit operations and had attained this standard in less than the minimum flight time contained in the operator's flying training syllabus.

At the time of the accident, the student's flying training included 3.6 hours dual night instruction, 2.5 hours night pilot-in-command, 4.4 hours instrument flying and 2.7 hours in a synthetic trainer. The syllabus indicated that a student required at least 9 hours in a synthetic trainer prior to commencing his night training, including a requirement for 5 hours of night simulation in the synthetic trainer. There was no provision for an exemption against those operations manual requirements.

Occurrence summary

Investigation number 200101929
Occurrence date 24/04/2001
Location Merredin, (ALA)
State Western Australia
Report release date 04/09/2002
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 None

Aircraft details

Manufacturer Grob - Burkhart Flugzeugbau
Model G115
Registration VH-BGQ
Serial number 82043/C2
Sector Piston
Operation type Flying Training
Departure point Merredin, WA
Destination Merredin, WA
Damage Substantial

Enstrom R.J. 280C, VH-SHK

Summary

The pilot of an Enstrom 280C helicopter was to conduct about 30 joy flights during the afternoon. Each flight was planned to last for about 3 minutes and carry two passengers. The flights commenced at approximately 1330 Eastern Standard Time and were to be finished by last light, which was 1758. The aircraft was refuelled twice during the afternoon, with the helicopter shut down and fuel transferred from jerrycans. The second refuelling was completed at about 1745.

Passengers then boarded the helicopter for the twenty-seventh flight of the afternoon. Witnesses reported that transition from the hover to forward flight appeared normal, and that they had then stopped watching the helicopter. A short time later they heard the sound of impact. The helicopter had struck a tree prior to impacting the ground. The occupants were not injured.

The pilot reported that the helicopter's engine did not appear to gain full power during the transition and climb and that he deliberately did not correct a minor out of balance situation to avoid overpitching the rotor. He assessed that there was sufficient engine power available to clear the trees and continue the flight. The area beyond the trees was clear so that if a problem occurred after he cleared the trees, he could have allowed the helicopter to descend to gain performance and continue the flight. The pilot said that the engine turbo-overboost light did not illuminate as it had done during previous departures.

The air temperature was about 28 degrees C. Witnesses reported that the wind at ground level had been calm during the day. The pilot reported that about 20 minutes before the accident, Archerfield Tower, which was about eight kilometres east of the accident location, reported the surface wind at Archerfield to have been easterly at 12 knots. Throughout the afternoon, movement of the treetops had indicated a steady wind. However, the pilot said that he did not have an opportunity immediately before the take-off to confirm the wind strength.

The pilot held a Commercial Pilot (Helicopter) Licence and had accumulated 200 hours total flying experience and 130 hours on the Enstrom.

A comprehensive examination of the engine found nothing that might have prevented it from operating normally.

In line with a normal diurnal wind variations, it is possible that the wind was beginning to die at the time of the accident (dusk). Because of the added fuel, the helicopter's all up weight was higher than for the previous take-off. Both of these changes, either separately or in combination, would have increased the power required for the helicopter to maintain the previously flown departure profile. The pilot would have needed to adjust the departure path or transition technique to account for the decreased performance available. The investigation was unable to determine if maximum engine power had been achieved.

Because no fault could be found with the engine, it was considered likely that the departure path or transition technique had not been sufficiently adjusted to account for the changed conditions. The pilot's low level of experience and the repetitive nature of the flying may have also been factors in the accident.

Occurrence summary

Investigation number 200101788
Occurrence date 11/04/2001
Location 8 km WSW Archerfield, Aero.
State Queensland
Report release date 11/02/2002
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 The Enstrom Helicopter Corporation
Model 280
Registration VH-SHK
Serial number 1146
Sector Helicopter
Operation type Charter
Departure point Basil Stafford Centre, QLD
Destination Basil Stafford Centre, QLD
Damage Substantial

Beech Aircraft Corp A36, VH-NKB

Summary

A Beechcraft Bonanza A36, with the pilot and one passenger on board, departed Swan Hill at approximately 1600 on 20 April 2001. The pilot had not submitted a flight plan to Airservices Australia and did not broadcast his intentions to an air traffic control unit. However, the pilot left details of the flight at the point of departure and arranged to phone a contact on arrival at Goulburn. At about 1735 a radar trace consistent with the flight path of the aircraft was identified approaching Goulburn from Yass. The aircraft disappeared from radar 7 NM west of Goulburn at 1744, which was consistent with the flight profile of a planned descent to Goulburn. The end of official daylight was 1758. The pilot did not report to the contact by phone as planned and a search for the aircraft commenced the next morning.

The aircraft wreckage was found 4 NM to the south-west of the aerodrome. The aircraft had been flying in a direction away from the aerodrome, when it collided with dense woodland on the far side of a hill. The measured descent path of the aircraft through the trees indicated a rate of descent well in excess of that normally found in controlled flight. The aircraft was consumed by post-impact fire. The accident was not survivable.

Examination of the wreckage found no evidence of any defect in the aircraft or its systems that may have contributed to the circumstances of the accident. The pilot was appropriately licensed to operate the aircraft in day visual conditions. He had completed 4.5 hours flight training towards qualifying for issue of the night visual flight rules rating, but did not hold that rating. The aircraft was not appropriately equipped, nor was the pilot qualified for flight in instrument meteorological conditions.

At the time of the aircraft's departure from Swan Hill meteorological reports indicated the en-route weather as fine. The destination forecast indicated cloud in the vicinity of the aerodrome and a requirement to expect the possibility of holding for up to 30 minutes, for weather reasons, before a landing would be possible. Witnesses reported that at the time of the accident there was fog and drizzle in the vicinity of the hill on which the aircraft impacted.

Persons who had flown with the pilot stated that they had flown with him at night and in conditions of poor visibility. They also reported that the pilot normally flew the aircraft with the aid of a moving-map display global positioning system.

The weather conditions facing the pilot in the Goulburn area, together with fading daylight, would have deprived the pilot of a visible horizon to assist in controlling the aircraft. This would have increased the probability of spatial disorientation and a subsequent loss of control.

The circumstances of the accident were consistent with the pilot attempting to continue the flight into non-visual meteorological conditions.

Occurrence summary

Investigation number 200101729
Occurrence date 20/04/2001
Location 8 km WSW Goulburn, (NDB)
State New South Wales
Report release date 03/08/2001
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 Beech Aircraft Corp
Model 36
Registration VH-NKB
Serial number E-933
Sector Piston
Operation type Private
Departure point Swan Hill, VIC
Destination Goulburn, NSW
Damage Destroyed

Amateur Built Lancair 320, VH-DNO

Summary

The owner of Lancair, VH-DNO, was in the process of selling his aircraft. He had arranged to meet some prospective purchasers at Mildura, and had flown from Maroochydore that morning so that the purchasers could inspect and fly the aircraft with him. He started the flight early in the morning and arrived in Mildura at lunch time. The day was warm and, as the top of the cockpit was transparent, the cockpit would also have been very warm. The pilot stated that he had consciously limited his fluid intake during the flight as the duration of each leg was fairly long.

Two people who had travelled to Mildura for the aircraft inspection were considering purchasing the aircraft together. When the vendor arrived at Mildura, he joined the two prospective purchasers in the airport terminal, where he drank some water and ate some fruit. As they discussed the aircraft, one of the purchasers emphasised his interest in the aircraft's take-off and landing performance and low speed handling characteristics. After about half an hour, the purchasers agreed which one would go for the first test flight and they went out to the aircraft. The vendor sat in the left (command) seat and the purchaser sat in the right (passenger) seat; both seats had functioning flight controls.

Approximately half an hour later, a witness who was working in a vineyard saw the aircraft flying straight and level, with power changing regularly from a high power setting to idle. A short time later, the witness looked up again when an unusual noise attracted his attention. He saw the aircraft descending in a spin and disappear behind a hill. Shortly after, he heard a sound consistent with the aircraft impacting the ground.

The aircraft had impacted the ground at high speed, in straight flight, with wings level and a steep nose down angle. Both occupants received fatal injuries. No indication was found of any pre-existing defect in the aircraft or the engine prior to the accident. The landing gear and the flaps were extended at the time of the accident.

The circumstances of the accident were consistent with a loss of control during a demonstration of the handling characteristics of the aircraft at low speed with landing gear and flaps extended. The aircraft entered a spin for reasons that could not be determined. The circumstances were consistent with the spin rotation having been arrested and the aircraft impacting the ground as it was accelerating during the pull out from a dive at the end of a spin recovery.

Occurrence summary

Investigation number 200101082
Occurrence date 13/03/2001
Location Nangiloc
State Victoria
Report release date 13/06/2001
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 Amateur Built Aircraft
Model Lancair
Registration VH-DNO
Serial number Q058
Sector Piston
Operation type Private
Departure point Mildura, VIC
Destination Mildura, VIC
Damage Destroyed

Cessna 210L, VH-BBI

Summary

The pilot, who was the sole occupant of the Cessna 210, was departing Lake Evella on a positioning flight to Elcho Island. Witnesses reported seeing the aircraft take-off and climb to about 400 ft above ground level. The aircraft then entered what was described as a `wing-over type manoeuvre' before descending steeply into the ground.

It was reported that, before the flight, the pilot had indicated his intention to conduct a low pass over the runway after take-off. It was also reported that the pilot had occasionally conducted low passes on arrival and departure at the airstrip.

New evidence presented to the ATSB on 16 October 2003 revealed that the aircraft impacted the ground in a 30 degree nose-low attitude, with the engine operating at low power. The evidence indicated that an engineering examination found no evidence of any pre-existing system malfunction which would contribute to a loss of engine power. At the time of impact the propeller blade angles were close to the fine pitch stop. The examination concluded that the engine, propeller and their associated systems were not a factor in the accident.

The aircraft was considered to have stalled and briefly auto-rotated, during which the nose dropped into a steep nose-low attitude. To the untrained observer that may have looked like a wing-over type manoeuvre. During the attempted recovery, the pilot may have closed the throttle to reduce acceleration and height loss. The height at which the stall occurred was about 400 ft and calculations suggest that the time to ground impact was about 4 to 5 seconds and the speed at impact about 100 to 120 kts.

Witnesses reported that the engine was operating at high power until impact, indicating that the engine noise ceased about the time of impact. The new evidence presented to the ATSB indicates that the witnesses who reported hearing the engine noise were about 1000 metres from the aircraft and any change in engine noise would have taken about 3 seconds to reach them. That would indicate that the pilot may have closed the throttle soon after the aircraft entered the dive.

The circumstances of the accident were consistent with the pilot attempting a manoeuvre after take-off, which inadvertently stalled the aircraft at a low height. Control of the aircraft was then lost with insufficient height remaining to effect recovery.

The ATSB did not conduct an on-site investigation into this occurrence. This report has been compiled from information provided to the Bureau.

Occurrence summary

Investigation number 200100591
Occurrence date 04/02/2001
Location 1 km E Lake Evella, Aero.
State Northern Territory
Report release date 11/12/2003
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 Fatal

Aircraft details

Manufacturer Cessna Aircraft Company
Model 210
Registration VH-BBI
Serial number 21060471
Sector Piston
Operation type Charter
Departure point Lake Evella, NT
Destination Elcho Island, NT
Damage Destroyed

Pitts Aviation Enterprises S-1E, VH-SIS

Analysis

Why the aircraft impacted the ground could not be determined.

It is possible that the air temperature and humidity affected the pilot's performance, however, the extent of any such affect could not be assessed.

The pilot's new parachute pack would have changed his position relative to the cockpit controls. A possible consequence was that, if the pilot used that relationship as a reference during manoeuvres, without adjusting for the parachute pack, the position of the flight control surfaces would also have changed when compared with previous flights performing the same manoeuvres. That could have resulted in the aircraft being operated outside the parameters previously established by the pilot for particular manoeuvres, such as by descending unintentionally.

Although the aircraft impacted the ground while tracking to the north-west, when the observer lost sight of it behind a ridge the aircraft was tracking in a south-easterly direction at a very low height. It is possible that the pilot discontinued the knife-edge manoeuvre and reversed the direction of flight while hidden from view by the ridge.

Summary

Sequence of events

The pilot of a Pitts aerobatic aircraft arranged to fly to a training area to the south of Archerfield in company with a friend in a Yak aerobatic aircraft. They planned to practise aerobatics for about 30 minutes. The area selected was over a pine forest with a duplicated high-tension power line traversing the forest. North of the power lines the trees had been cleared and grass to about 500 mm high was the only significant vegetation in the area. The terrain was gently sloping up towards the north-west. The pilots agreed to operate on either side of the power line with the Pitts operating to the north of the line.

When the pilot of the Yak aircraft completed his sequence he attempted, unsuccessfully, to contact the Pitts pilot by radio. He also could not see the aircraft. When he flew closer to the power line he observed a small fire and realised that the Pitts aircraft had crashed. The pilot then contacted the Archerfield Air Traffic Controller to alert emergency services.

A resident located north-east of the accident site had observed the Pitts aircraft flying manoeuvres parallel to the power line. During one manoeuvre conducted to the north-west and away from the observer, the aircraft appeared to be flying straight, with the wings vertical, as if in a manoeuvre known as a "knife-edge". The upper side of the fuselage was directed away from the power line. The aircraft appeared to be descending but the person was aware that the aircraft was moving away and thought that the apparent descent may have been an illusion. After a vertical climb and descent involving rolling manoeuvres, the aircraft again flew in a straight line with the wings vertical. On that occasion the aircraft was tracking to the south-east and toward the observer, and the upper fuselage was again oriented away from the power line. The observer stated that the aircraft appeared to be descending, and passed from sight behind a low ridge. He did not see the aircraft again and sometime later saw smoke rising from behind the ridge.

Aircraft examination

The aircraft impacted the ground in a wings-level attitude at a speed estimated at more than 100 kts, while travelling in a north-westerly direction. At the time the aircraft was descending at about 30 deg nose down, and appeared to have been in balanced flight and at a low "g" loading. The impact was considered not survivable. The aircraft did not bounce, coming to an extremely rapid stop in the sandy soil. The fire would have broken out immediately, as a result of the ruptured fuel tank and disruption of the electrical system. The aircraft was destroyed by impact forces and the post-impact fire.

The engine was dissassembled and inspected. The crankshaft had moved rearward by about 6 mm relative to the crankcase, a further indication of an abrupt stop. The lack of damage to the cylinders indicated that the propeller and crankshaft had taken most of the deceleration loads, transmitting them through the crankcase to the airframe. There was no indication of mechanical failure prior to impact. The available information suggested that the engine was operating at low to moderate power at impact.

The Pilot

The pilot held a private pilot's licence to fly aeroplanes. His Class Two medical certificate was valid until June 2001. He had commenced flying training in January 1983 and obtained an aerobatic rating in March 1995. The rating was progressively upgraded, and in November 2000 the pilot was approved to conduct aerobatics to a minimum height of 100 ft.

The pilot purchased the Pitts aircraft in September 1997 and had flown it almost exclusively since then. His most recent biennial flight review, which included aerobatic flying, was conducted in May 1999.

Although he normally flew without a parachute, on the accident flight the pilot was wearing a new parachute pack for the first time. The pack thickness was about 4 cm.

Weather conditions

At the time of the accident the sky was clear of cloud, and the wind was a light south-westerly. The pilot of the Yak aircraft assessed that the temperature was in the mid-thirties [Celsius]. The temperature and humidity at the accident site were considered by an experienced pilot to be such that conditions in the cockpit of the Pitts aircraft would have been oppressive.

Aerobatic manoeuvres

One of the manoeuvres the pilot was intending to practise was a "knife-edge" manoeuvre where the aircraft was flown straight and level while banked 90 degrees left or right. That manoeuvre was referred to as a stick-position manoeuvre, because the positioning of the control column and rudder pedals must be precise to place the aircraft in the correct attitude and flight path. Practice and familiarity are the primary means of ensuring accuracy.

In the immediate vicinity of the crash site there were no prominent visual indicators for the pilot to judge the height of the aircraft above the ground. The vegetation was low and devoid of trees, and the terrain was not sufficiently sloping to provide the pilot with good height cues.

Examination of terrain contours and the location of the observer indicated that the aircraft was probably below 30 ft above ground level at the time it was lost from sight behind a ridge.

Occurrence summary

Investigation number 200100347
Occurrence date 28/01/2001
Location Logan Village
State Queensland
Report release date 17/01/2002
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 Pitts Aviation Enterprises
Model S-1
Registration VH-SIS
Serial number W69
Sector Piston
Operation type Sports Aviation
Departure point Archerfield, QLD
Destination Archerfield, QLD
Damage Destroyed
Subscribe to Collision with terrain
Return focus to the top of the page