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.

The pilot reported that after selecting the landing gear down he failed to obtain a safe down and locked indication. He notified the Tower of the situation, then retracted the landing gear and attempted a manual extension. He disarmed the landing gear circuit breaker, placed the selector switch to the "DOWN" position, disengaged the motor release arm and inserted the gear extension handle into the right socket, and after reducing airspeed, pushed the handle as far forward as it would go. As he was still unable to obtain a down and locked indication, he landed the aircraft, but the landing gear collapsed during the landing roll.

Investigation determined that the landing gear functioned normally during ground testing. The navigation lights were on at the time. This automatically dims the landing gear indication such that it is difficult to see in daylight. The pilot therefore assumed that the gear had not locked in the "DOWN" position after the first extension and he elected to attempt a manual extension. However, the pilot failed to complete the manual extension procedure which requires that after positioning the handle full forward in the right socket, the handle is then inserted into the left socket and the procedure repeated. This failed to lock the landing gear in the "DOWN" position, which subsequently collapsed under the landing loads. The pilot reported that in the fifteen years he had owned the aircraft, he had never performed a practice manual extension of the landing gear in flight.

The pilot was carrying out a fence inspection at 500 feet above ground level when the engine power reduced to idle. He changed the fuel tank selector to the fullest tank but there was no response from the engine. The pilot then closed and opened the throttle lever a number of times. This resulted in an increase to 1000 revolutions per minute, but power again returned to idle when he stopped moving the throttle. As the aircraft was losing altitude the pilot discontinued his trouble shooting activities and attempted a forced landing in heavily timbered terrain. The aircraft struck a number of trees during the landing.

The only fault found during an inspection of the wreckage was a fuel tank vent line containing a wasps nest. Testing of the line indicated that the nest could move causing either a partial or full blockage. The vent outlet was covered with a piece of gauze to prevent this type of occurrence. The fuel tanks were fitted with vented fuel caps.

The reason for the loss of power was not determined.