Sequence of Events

The aircraft was on a night departure from runway 22. Shortly after a normal take-off it struck trees 439 metres from the departure end of the runway. The aircraft then impacted the ground and slid to a stop approximately 360 metres further on. The aircraft was destroyed by a post impact fire. All occupants were able to evacuate the aircraft although they received significant burn injuries.

This summary looks at the factors leading to the accident, some of the events surrounding the post impact evacuation and safety action already taken.

Accident Analysis

The aircraft was in controlled flight, in a shallow descent with wings level, at impact. All aircraft systems were reported to be operating normally at the time.

Evidence indicates that the pilot flew the aircraft to an initial 10 degree nose up attitude after lift-off. However, he then selected the landing gear up, turned the landing light off, introduced forward elevator trim, to relieve an apparent nose up tendency, and attempted to make a radio call. It was during these activities that the aircraft descended and struck the trees.

The pilot, who was a very experienced instructor, met all night flying recency experience requirements at the time of the accident. Evidence indicates that the pilot had commenced work at approximately 0330, on the day prior to the accident. The aircraft arrived at Halls Creek around 1130, and post flight activities were completed by 1200. The pilot then proceeded, by vehicle and in the company of the passengers, to inspect a drill site, arriving back at the motel about 1630.  He attended a barbecue, completed planning for the next day's flying and loaded some of the baggage on to the aircraft before retiring for the night. He had about six hours sleep immediately prior to commencing duty at 0330 on the day of the accident. The pilot had planned to depart after breakfast however he had been asked, by his company, to bring the flight forward as a piece of defective machinery was required in Perth as soon as possible. He calculated an earlier departure time based on his assessment of minimum crew duty times as set out in Civil Aviation Order (CAO) 48.

The outside environment (no ambient lighting, no visible horizon) was such that the pilot, immediately after lift-off, had to make a transition from outside visual references (runway, runway lights etc.) to total reliance on the aircraft flight instruments for the aircraft to be flown safely away from the runway environment.

If an effective cross reference of the instruments was not established immediately, potential existed for the aircraft to descend. To establish an effective cross reference, a pilot must accept that dark night take-offs need to be conducted in accordance with the procedures normally used for a departure in instrument flying conditions. The actions of the pilot in becoming involved in other activities including the attempted transmission of a departure report, so soon after liftoff, indicates that he had not fully accepted the instrument flying conditions criteria. In addition, the application of nose down trim probably started a descent that went unnoticed by the pilot whilst he was distracted by his other activities.

The pilot advised the investigation team that he was not aware of the somatogravic illusion commonly associated with dark night take-offs. The somatogravic illusion, as outlined in Note 1, is a condition that could also have made the pilot's concentration on a safe departure difficult. The possible presence of fatigue would have increased his susceptibility to the illusion.

Aviation safety research indicates that accidents often occur at a low point in a pilot's circadian rhythm (which often occurs in the early hours of the morning) and/or if a pilot's intake of nourishment is inadequate. The pilot reported that he ate normally except that he did not have any breakfast on the morning of the accident. Whilst no direct evidence was available to support a positive conclusion, the flight timings and other activities indicate that both of these factors may have been relevant to the accident sequence.

The known facts concerning the pilot's post lift-off activities, the aircraft's flight profile and the environment to the south-west of the airfield (the prevailing visibility and darkness conditions) suggest that the pilot did not apply the correct departure techniques and that he probably experienced a somatogravic illusion. It is possible that fatigue, a low circadian rhythm and irregular nourishment made him more susceptible to the illusion.

Evacuation Analysis

The investigation determined that the pilot did not conduct a pre-departure safety briefing at either Jandakot, for the flight to Halls Creek, or immediately prior to the departure for the accident flight. Although it was the pilot's normal practice to conduct such a briefing, and it was a company operation's manual requirement to do so, no information was available which would explain the omissions on these occasions. Consequently, none of the passengers were aware of the correct procedure for evacuating the aircraft in the event of an emergency. There were three emergency exits in the cabin area of the aircraft. Two over-wing window exits and a rear door exit. The safety briefing normally covers the use of the emergency exits. In the case of VH-CFG, the release mechanism was such that knowledge on how to operate the emergency exits was essential for a passenger to be able to escape through these openings under conditions of high stress.

One passenger indicated that, after the aircraft had stopped and become engulfed in fire, he observed the sign indicating the location of an emergency window exit but was unable to determine how it operated or to force his way out through it. He had then attempted to escape by moving to the rear of the cabin area only to find that there was no apparent way out. An emergency door exit was located at the rear of the cabin, but he was not aware of this fact. A second passenger also attempted, unsuccessfully, to open an emergency window exit.

All occupants, including the two passengers sitting in the middle row of seats adjacent to the emergency exits, were forced to escape through the normal entrance door located on the forward, right side of the combined cabin/cockpit. This led them through the main fire zone.

Safety Action

As a result of concern over a number of previous accidents with circumstances generally similar to this accident, the Bureau of Air Safety Investigation published a research report, in early 1995, titled Dark Night Take-off Accidents in Australia (SAB/RP/95/01).

Research report SAB/RP/95/01 included the following recommendation:

R940219.

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

1. integrate and expand human performance and limitation considerations into the day VFR syllabus at and above the level of the GFPT for the private pilot licence;
2. review the policy on the testing of human performance and limitation considerations and include this area as an examinable part of the syllabus above the level of the GFPT for the private pilot licence;
3. review theory requirements of the instructor, night VFR and instrument ratings, with emphasis on the specific operational and human-factors considerations that the use of these ratings require as compared to day VFR flight;
4. review the practical requirements of the syllabus leading to an instrument rating, to ensure that a candidate has experienced conditions of IMC and flight (including take-offs and landings) at night, in areas with limited lighting, before being granted a rating;
5. review the policy applicable to the renewal and recency requirement of the night VFR rating, to ensure renewal and recency requirements are similar to other instrument ratings; and
6. educate pilots and operators of the effects of fatigue and the need to establish flight and duty times that are commensurate with the demands of their flight operations. In particular, it should stressed that the limits imposed by CAO 48.0 are maximum limits and lower limits may be appropriate to some types of operations.

Note 1. - The Somatogravic Illusion

'If one considers an aircraft flying straight and level and accelerating along the direction of flight because of an increase in power, for example, then the direction of the inertial force due to the acceleration is to the rear of the aircraft and for the purposes of this discussion can be assumed to be along the longitudinal axis of the aircraft. This inertial force combines with the force of gravity to produce a resultant which is inclined to the rear of the aircraft. If this resultant is then used by the pilot as the vertical reference, then the pilot will incorrectly sense that the aircraft is in a nose-up attitude. If the pilot then trims or eases forward on the control column to correct for this nose-up perception, the nose of the aircraft will drop, and the airspeed will increase. This change in attitude will change the direction of the resultant force vector in such a manner as to maintain and perhaps magnify the illusory perception of a nose-up attitude.

Significant errors in perception can develop within the first few seconds of a change in the force environment. Experiments carried out in flight have shown that there is little lag in the onset of the illusion and that there is a relatively rapid increase in its magnitude during the initial six to eight seconds. This illusion is known as the somatogravic illusion, and it is particularly dangerous when it occurs on take-off or when overshooting, especially at night or in poor visibility. An aircraft deceleration will result in the opposite effect, that is, a perceived nose-down attitude. '

Transportation Safety Board of Canada, Report 89H0007

The pilot was a student with limited experience. He was attempting a flapless approach and landing.

The pilot reported that the airspeed was higher than required as the aircraft crossed the threshold and when he attempted to land the aircraft it touched down nosewheel first. Following a number of bounces the pilot opened the throttle and attempted to go around for another circuit. As he did so the stall warning sounded. The pilot closed the throttle and attempted a final landing. A combination of low airspeed and inexperience caused the pilot to loose directional control and the aircraft turned approximately 30 degrees off runway heading. The aircraft touched down on the grass flight strip, to the left of the runway, and ran across the grass for approximately 80 metres before turning through 180 degrees and stopping.

The pilot said that he had intended to fly practice circuits in the tailwheel aircraft. During the landing roll of his first circuit, he lost directional control at about 25 to 30 knots indicated airspeed. After yawing first left then right, the aircraft entered a ground loop to the left at about 20 to 25 knots. The right-wing tip and right tail plane made contact with the ground.

The aircraft was taxied back to the hangar.

The passenger, who was an experienced instructor but was on board as a passenger, indicated that the pilot had made inappropriate control inputs following touchdown. This led directly to a loss of control. An intercommunication system was not fitted in this aircraft.

FACTUAL INFORMATION

A Cessna 310 aircraft was operating a scheduled low-capacity regular public transport (RPT) flight from Deniliquin to Canberra. Due to fog extending from the surface to approximately 400 ft above ground level (AGL), the aircraft had been cleared to conduct an instrument landing system (ILS) approach to runway 35 at Canberra. The pilot was about to execute a go-around from the minima when he sighted the runway 35 high intensity approach lights (HIAL). He recalled seeing beyond the runway 35 threshold to the first taxiway and almost to the runway intersection: approximately 600 m and 900 m from the threshold respectively. The pilot elected to continue the landing. Just as the aircraft was about to flare, the aerodrome controller (ADC) instructed the aircraft to go around. The ADC subsequently advised the Cessna 310 pilot that an airport safety officer's vehicle had entered runway 35 at the threshold. Following two unsuccessful ILS approaches, the Cessna 310 diverted to Moruya. The Federal Airports Corporation (FAC) vehicle was being driven by a airport safety officer who had been conducting frequent visibility checks prior to the first aircraft departure. Normally all runway operations were conducted whilst communicating with the ADC while any other surface operations were conducted on the surface movement controller (SMC) frequency.

On this occasion, the safety officer had been requested by the SMC to conduct runway visibility checks for runway 35 on the discrete SMC frequency in lieu of frequent switching from SMC to the ADC frequency. Prior to the occurrence, the vehicle had been authorised to enter and vacate runway 35 a number of times using this communication procedure. The safety officer had neither expected, nor been aware, that the Cessna 310 was making an ILS approach to runway 35. Because all communications were conducted on the SMC frequency, the opportunity for the safety officer to intercept transmissions between the ADC, the Cessna 310 or any other inbound aircraft was excluded. The safety officer recalled driving past the holding point onto the runway 35 threshold and that the vehicle was approximately mid-way between the left runway edge lighting and the extended runway centreline when he saw the Cessna 310 pass about 50 ft overhead and execute a go-around. The safety officer immediately realised that he had entered runway 35 without a clearance. The automatic terminal information service (ATIS) was transmitting information 'Alpha' for the period surrounding the occurrence. This indicated runway 35 was the duty runway, the surface wind was light and variable, QNH 1027, temperature one degree Celsius and visibility reduced to 800 m in fog. The ATIS also advised that pilots could expect an ILS approach with radar vectoring and that the HIALs were on. Consequently, visibility from the control cabin was reduced such that the SMC could neither see the runway intersection, runway 35 threshold, the vehicle nor the Cessna 310. The SMC was aware that the Cessna 310 had been cleared to land if the ILS approach was successful. He did not expect the vehicle to enter the runway without first obtaining a clearance. When the runway incursion by the vehicle was apparent and the actual position of the Cessna 310 was unknown, the ADC instructed the Cessna 310 to execute a go-around. Simultaneously, the SMC instructed the safety officer to vacate the runway. ANALYSIS Runway 35 is a category one precision approach instrument runway served by an ILS and visual aids which permit operations down to a decision height of 330 ft and visibility of 1,200 m while the HIALs were operational. The ATIS report that visibility was reduced to 800 m in fog, implied that visibility may be greater than 800 m.

However, actual runway visibility reports provided primarily by the FAC airport safety officer indicated a visibility fluctuating between 300 and 1,000 metres for runway 35. The pilot stated that he flew the ILS to the missed approach point of 2,200 ft, where he had become visual. He had been about to go-around when he sighted the runway 35 HIAL and the runway 35 threshold through light mist. He added that although he could not sight the T-VASI, he elected to continue the approach. He did not see the safety officer's vehicle on the threshold. Air traffic control do not have the authority to close a runway or an aerodrome due to meteorological phenomenon. Additionally, a pilot may:

a) make an approach for the purpose of landing at an aerodrome; or

b) continue to fly towards an aerodrome of intended landing specified on the flight plan; if the pilot believes on reasonable grounds that the meteorological minima determined for that aerodrome will be at, or above, the meteorological minima determined for the aerodrome at the time of arrival at that aerodrome. Consequently, the pilot in command of an aircraft is responsible for ascertaining if weather conditions are suitable for the conduct of an instrument approach and landing.

The distance from the missed approach point to the runway 35 threshold is approximately 925 m with the HIALs contained within the last 800 m. The distances from the runway 35 threshold to the T-VASI, first taxiway and intersection are approximately 300 m, 600 m and 900 m respectively. Therefore, for a pilot to achieve the required 1,200m visibility at the missed approach point would require the T-VASI to be in sight. While the ATIS was indicating a runway visibility 'reduced to 800 m', the availability of ILS approaches and the departure of other aircraft, would indicate to a pilot conducting an ILS approach that he could expect a successful approach and landing. However, upon reaching the minima, it becomes a very different scenario when the visibility is considerably less than expected. It becomes a matter of judgement between the pilot's estimate for the required visibility and a safety officer counting runway lights to report actual runway visibility.

The evidence indicates the Cessna 310 pilot may have deviated from the prescribed minima requirements by continuing the approach with a reported visibility, at the time, of approximately 400 m at the threshold of runway 35. While he believed his decision to have been correct, it is considered highly unlikely that the required runway visibility of 1,200 m could have existed. If the required visibility did exist, then it was so marginal that a 1,200 m visibility could not have been maintained if the vehicle on the threshold and the T-VASI could not be seen. The safety officer believed that the runway was closed and that the visibility checks were for the departure of a Dash 8 aircraft currently at the terminal. The safety officer could not recall receiving, nor requesting, a specific clearance from the SMC to enter runway 35. However, on many previous requests from SMC, the request and clearance to enter the runway were embedded in one transmission. Consequently, the safety officer had not been required to stop at the runway holding points, change to the ADC frequency and request a specific clearance to enter the runway. The deviations from standard operating procedures and phraseology by the SMC and the airport safety officer created an environment of ambiguity associated with expectation and repetition of previous runway clearances. Retaining all communications with the safety officer on the SMC frequency eroded one of the system defences until there was a failure; the safety officer forgot to obtain a clearance to enter the duty runway. Collectively, deviations from standard operating procedures and standards by the SMC, safety officer and the pilot of the Cessna 310 did not allow for lapses in judgment, practices, decision making and, effectively, removed human performance redundancies.

CONCLUSION

Findings

1. Ad hoc variations to standard operating phraseology between the airport safety officer and the SMC, whilst conducting runway visibility range assessments, were inappropriate.

2. The ATIS transmission indicating that visibility was reduced to 800 m created a false expectation for the flight crew of arriving aircraft.

3. Both the SMC and airport safety officer failed to achieve complete and comprehensive transfer of situational awareness information.

4. The airport safety officer omitted to obtain the required clearance prior to entering the duty runway.

5. The pilot in command of the Cessna 310 continued the approach, below the decision altitude, from a position where the T-VASIS could not be sighted and the runway visibility range at the threshold was approximately 400 m.

Significant Factors

1. The airport safety officer lost situational awareness and omitted to obtain a clearance prior to entering the duty runway.

2. The pilot in command of the Cessna 310 misjudged the required visibility of 1,200 m and continued the runway 35 ILS approach when visibility was below the published minima.

SAFETY ACTIONS

Following this occurrence, the FAC initiated amendments to the Canberra Airport Operations Manual addressing low visibility operations. Additionally, some aspects of deficiencies of airside vehicle operations have been addressed as a consequence of recommendations resulting from Investigation Report 9301481 issued in July 1994.

Whilst taxiing for departure, the pilot of VH-CLA noticed that the left brake was becoming progressively less effective. He attempted to slow the aircraft by closing the throttles and using the right brake with full left rudder application. However, this proved ineffective. As directional control was becoming difficult the pilot elected to turn the aircraft to the right onto the grassed area beside the taxiway. He applied right brake, but the aircraft turned rapidly through about 165 degrees and collided with VH-ILS which was following behind.

The pilot of VH-ILS reported he had lost sight of VH-CLA immediately prior to the collision due to condensation on the inside surface of the windscreen, and from watching another nearby aircraft.

Investigation later determined that the left brake piston seal was in poor condition and leaking, and the master cylinder was almost empty. There was an outstanding entry on the Maintenance Release to bleed the right brake.

The pilot was taking some friends for a short flight before the end of daylight. Just prior to touchdown he became aware that the landing gear was not extended, and as he believed it was too late to attempt a go-around, he landed the aircraft with the landing gear retracted. The aircraft slid to a halt on the runway and all the occupants evacuated uninjured.

The pilot reported that he believed he had not been distracted prior to landing and that he completed the prelanding checks but had not noticed that the landing gear was not extended.

When the aircraft came to rest it blocked both runways. Due to the imminent arrival of two scheduled services the pilot advised off duty airport ground staff, who organised the removal of the aircraft from the runway.

It was reported that fuel usage during the flight appeared to be excessive, and the burner flames were more yellow coloured than normal. The pilot suspected a problem with the fuel gas and decided to land before his supply ran out. During the approach, the pilot had difficulty in controlling the descent accurately because of an unusually slow response to control burns. Following three landing attempts, the balloon was landed in pine trees. Eleven envelope panels were torn.

Investigation with the gas supplier revealed that the fuel mixture was not the 97% Propane requested but a mixture of 35% propane and 65% propylene. It was not the first flight using this fuel mixture, but it was the first time that the outside air temperature was as low as +5 degrees Celsius. Subsequent tests by the operator showed that the burners were inefficient with this gas at the lower temperatures.

FACTUAL INFORMATION

The aircraft was making its last spray run before refuelling when it suffered a loss of engine power. The pilot climbed the aircraft while attempting to restart the engine.

When the engine failed to respond, a forced landing was carried out into a paddock but during the landing roll the aircraft entered a 2-metre-deep ditch at low speed, causing damage to the propeller and left wingtip.

Subsequent inspection revealed that while there was a small amount of fuel in one wing tank, the header tank feeding the engine was empty.

ANALYSIS

When the aircraft type was originally designed, it was fitted with a radial piston engine. A turboprop engine was fitted to later models, and the fuel system was redesigned with a small header tank in the fuselage between the wing tanks and the engine. The header tank should supply fuel to the engine for a short time if the tank outlets become uncovered by fuel during manoeuvring with small amounts of fuel remaining.

If the fuel supply to a turboprop engine is interrupted and then restored, the engine is not likely to restart without action from the pilot unless an automatic re-ignition system is installed. There was no such system on the accident aircraft.

Other similar engine failures have been experienced with this type of aircraft due to the location of the fuel tank outlet, which can become uncovered when the fuel level in the tank is low, and the aircraft is in a nose-down attitude.  This was the most likely situation which led to interruption of the flow of fuel to the header tank and to the engine of VH-ODR.

SIGNIFICANT FACTORS

1. The aircraft was operating with a small amount of fuel in the wing tanks.
2. Although there was some fuel in one wing tank, the header tank feeding fuel to the engine was empty probably because a nose-down attitude allowed the tank outlets to become uncovered.
3. The engine failed, probably because of fuel starvation, at too low a height for the pilot to effect a restart.

SAFETY ACTION

As a result of the investigation into this and a subsequent occurrence (BASI No. 9601185, VH-XST), the Bureau of Air Safety Investigation forwarded the following Safety Advisory Notice to the Civil Aviation Safety Authority (CASA) on 1 July 1996.

SAN960052

The Bureau of Air Safety Investigation suggests that the Civil Aviation Safety Authority, in consultation with the US Federal Aviation Administration (FAA), review the fuel system design of aircraft conforming to Type Certificate A17SW to ensure the adequacy of the fuel system with all applicable airframe/engine combinations.

The CASA response dated 18 July 1996 stated in part: 'I have written to the President of Air Tractor, and the Small

Airplane Directorate of the Federal Aviation Administration, advising them of the fuel starvation incidents in

Australia and asking for their comments.  I will advise you of the responses when I receive them.'

The aircraft was cruising at a height of about 800 feet above the ground when the pilot noticed a reduction in engine power. Application of carburettor heat and changing fuel tank selection made no difference. The loss of power was accompanied by an unusual engine sound. A total loss of engine power followed, and the pilot made a forced landing in a paddock. During the landing roll the right wing stuck a fence post.

Inspection of the aircraft showed the crankcase had a hole in it.

Significant Factors

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

1. Engine failure.

2. Collision with a fence post on the ground roll.

The helicopter had been chartered to transport persons associated with a Fraser Island resort to the area of the wreck of the "Maheno". After picking up a third passenger at the resort the helicopter headed north along the beach, flying passed the wreck, before heading in a southerly direction prior to commencing the approach to land.

The pilot stated that he was making an approach over the water to land on the beach to the north of the wreck when, at about 30 feet above sea level, he felt a "stiffness" in the cyclic control as he attempted to move it forward. Before he was able to access the situation, the helicopter descended into the water. The aircraft remained upright, and all the occupants evacuated and made their way to the shore. The helicopter was subsequently rolled onto its side as a result of wave action.

Inspection of the wreckage and testing of the hydraulic components of the helicopter could find no fault with either the aircraft or the hydraulic system. The reason for the reported control stiffness could not be determined.