An early morning flight was arranged between the owners of the Gipsy Moth VH-UQV and the owner of a Tiger Moth VH-DDA with the intention of photographing the Gipsy Moth from the air. The owner of VH-DDA agreed to fly in the Gipsy Moth and occupy the rear seat whilst the pilot-in-command occupied the front seat. The Tiger Moth was flown by the other owner of the Gipsy Moth. The Gipsy Moth was flown by the rear seat pilot for the first part of the flight. At the completion of the photography, which was conducted in the circuit area at Maitland, the pilot-in-command took control of the aircraft. The aircraft was flown to the north-east of the aerodrome to the Hunter River where it was descended to fly at a low height over the river. With the pilot in-command still at the controls, the aircraft returned to the aerodrome at a height of about 500 feet. After passing the aerodrome southern boundary, the aircraft entered a steep turn to the left. The non-flying pilot in the rear seat reported the aircraft, whilst passing through a north westerly heading, was rolled to the right to avoid a tree. The right wing struck and severed a cable of an 11,000 volt power line causing the aircraft to cartwheel into the ground, within the aerodrome boundary. This accident was not the subject of a formal on scene investigation.

During cruise, the engine started to run roughly. The pilot found that he could not maintain altitude and elected to land on a narrow road, this being the only area clear of trees. During the landing, the wing struck the ground. The cause of the engine problem was not determined. This accident was not the subject of a formal on-scene investigation.

On landing the basket touched down once, lifted back into the air and touched down a second time about 10 metres further on. The landing was not heavy and it was described as normal by an expert witness. The basket remained upright throughout the landing. One of the passengers apparently shifted position during the landing sequence and this resulted in her receiving a broken ankle. This accident was not the subject of an on-scene investigation.

Circumstances:

Towards the completion of a scenic flight with five adult passengers on board, the pilot descended the balloon to a height of approximately 200 feet above ground level and commenced searching for a suitable landing site. His initial selection was subsequently abandoned to avoid frightening an injured horse. The balloon with limited fuel remaining continued at low level, passing over timbered country before commencing a deflated landing into a semi cleared area. The area was surrounded by tall trees to the left, right and rear of the flight path. A two-wire high voltage set of powerlines located just ahead of the pilot's proposed landing area, were not sighted by a ground retrieval crew member, who was in the vicinity of the landing site and in radio contact with the pilot, nor apparently by the pilot until late into the landing. The passengers had not been briefed to assist in observing for and reporting powerlines. The pilot then issued instructions which his passengers understood to mean that they prepare to exit the balloon basket. When approximately one metre above the ground, the first passenger evacuated the basket followed by the pilot, who had the fabric covered metal parachute vent line wrapped in a spiral around his forearm. With the load reduced the balloon began to ascend. One flying wire supporting the balloon basket at the lower section of the balloon envelope, contacted the powerlines before the balloon descended again. An electrical discharge was heard, and one powerline was severed. As the basket neared the ground a second and third passenger exited. The pilot was then observed lying on the ground fatally injured, apparently having received a high voltage discharge via the parachute vent line. The line had then detached from around his forearm. A fourth passenger then vacated the basket, leaving one passenger on board. With the release of the parachute vent line the exhaust vent closed and as there was still sufficient buoyancy retained within the envelope, the balloon slowly re-ascended. When at an estimated height of 10 metres above the ground, the remaining passenger was observed to fall from the balloon basket and receive fatal injuries. The balloon continued to drift for approximately two kilometres before settling to the ground in heavily timbered country. The pilot's technique of wrapping the parachute vent line around his wrist and forearm would have made rapid deflation difficult. His actions in preparing passengers to jump and his decision to exit the basket prior to landing, were totally alien to the normal and emergency modus operandi. It is believed that a previous similar type fatal accident involving a balloon colliding with a powerline, may have influenced his behaviour. Subsequent trials indicated that it is extremely difficult to evacuate all passengers from a basket in a short time frame without pre-warning, established drills, and orderly implementation. The weather conditions were calm and clear, but the early morning ambient light conditions would have made detection of the powerlines difficult. The area selected for the landing was the only alternative available considering the meteorological conditions and fuel remaining. The size of the area should have been within the capabilities of the pilot and balloon had there been no powerlines across the flight path. Stringent obstacle clear gradient requirements exist for the selection of take-off sites, but not for landing sites. Despite some instrumentation deficiencies, the balloon and all of its relevant equipment was serviceable and had been maintained in accordance with approved procedures. Electrical bonding and insulation properties of the balloon were considered to be inherent design deficiencies for this type of aircraft, thereby permitting differing electrical potentials to exist between individual components, particularly in the event of powerline contact.

Significant Factors:

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

1. The aborted landing to avoid injured stock placed the pilot in an emergency landing situation.

2. The lack of timely detection of powerlines deprived the pilot of vital pre-landing information.

3. The evacuation of the basket prior to touchdown made pilot control of the balloon buoyancy difficult.

4. The pilot could not deflate the envelope before the balloon ascended into the powerlines.

5. Lack of effective electrical insulation and bonding properties facilitated the conduct of the electrical discharge to earth.

6. The pilot received a fatal electrical high voltage charge through the parachute vent line which was wrapped around his forearm.

7. The balloon contained sufficient buoyancy to ascend after the parachute vent line became free and the parachute vent closed.

8. The pilot's actions may have been influenced by a similar previous accident.

Recommendations:

It is recommended that the Civil Aviation Authority in conjunction with the Commercial Balloon Operators and the Australian Ballooning Federation, reassess existing requirements for commercial balloon operations and surveillance of standards and in particular give consideration to

1. Initiating a research and development programme into an on-board, electronic, directional, powerline detection device.

2. Redefining the Flight Manual Emergency Landing procedures concerning the briefing of passengers before ground contact, with particular emphasis upon orderly basket evacuation methods.

3. Initiating manufacturer approved methods of reducing the amount of exposed metal and providing electrical bonding of all metal components to achieve a neutral electrical potential difference between any two components.

4. Defining minimum obstacle clear approach parameters and gradients for commercial balloon landing sites consistent with balloon size and prevailing meteorological conditions.

5. Ensuring, as far as is practicable, that at least one member of the retrieve crew is either present at the proposed landing site, or in such other position with unrestricted views, as to be able to brief the pilot of obstacles and assist with rapid deflations and evacuations as required.

Five hot air balloons, including the two involved in the collision, VH-NMS and VH-WMS, were operating tourist charter flights from the same launch area. Flight plans had been submitted and correctly co-ordinated. All the balloons were ready at about the same time and took off within minutes of each other. VH-WMS was airborne about two minutes ahead of VH-NMS. The pilot of VH-WMS then requested an Airways Clearance for both his aircraft and VH-NMS. A clearance was issued for them to operate in the Alice Springs Control Zone not above 4000 feet. VH-WMS acknowledged for both aircraft. This clearance did not make specific reference for them to operate as a formation, but to operate in company. VH-WMS climbed to 4000 feet (2000 feet above ground level) and drifted in a westerly direction. Witness evidence revealed that the pilot did not use the burner for a considerable period of time while pointing out places of interest to the passengers. A video film taken from another balloon indicates that VH-WMS appeared to be descending at this time, while VH-NMS was climbing to follow it. During the climb the pilot of VH-NMS would have lost visual contact with VH-WMS due to his envelope causing a blind area above. VH-WMS was not fitted with the mandatory instrument package, without which the pilot would have been unable to accurately ascertain his altitude or judge his vertical movement. The pilot was wearing a wrist altimeter. Several of the passengers in VH-WMS had noted that the other balloon, VH-NMS, was below and climbing towards them from the east. They reported that it seemed to close on them at a fast rate until its envelope struck their basket. Evidence indicates that neither of the pilots were in contact with one another. Both balloons were equipped with UHF (Ultra High Frequency) radios operating on the same frequency. The basket of VH-WMS contacted the envelope of VH-NMS just below the velcro rip panel, tearing a hole in the fabric panel, which was under tension from containing the large mass of hot air within the envelope. Tearing continued through adjacent panels and seams, creating a hole large enough for the basket of VH-WMS to enter and proceed more than half way down into the interior of the envelope. At the point where the basket of VH-WMS moved inside the envelope, it would have contacted and fouled against the control lines for the velcro rip panel vent, initiating activation of the rip panel Capewell safety locks, and as it moved further inside would have contacted the control line for the parachute vent. The parachute vent line remained fouled around the outboard end of the basket of VH-WMS as it swung clear of the hole in the envelope of VH-NMS. This caused the velcro rip panel to fully open as the two balloons separated. VH-NMS then descended as hot air escaped through the damaged envelope panels and opened velcro rip panel, causing the envelope to elongate and rapidly collapse. The degree of disruption of the envelope was such that the balloon could not remain inflated. The basket, with the deflated envelope trailing above it, then plummeted to the ground. The investigation did not reveal any abnormalities or defects to the balloon, its envelope material or methods of manufacture, which could be considered to have contributed to the accident. Following the accident, the pilot of VH-WMS mentioned to one of his passengers that he had not noticed the other balloon before they collided. Subsequently, the pilot of VH-WMS, following legal advice, refused to co-operate fully with the Investigator-In-Charge in spite of having been summonsed under the provisions of the Air Navigation Act. The Company's Operations Manual states - "FORMATION FLIGHT When two or more balloons are flying together the upper balloon must give way. Avoid basket to envelope contact when taking off or in close proximity."

Circumstances:

Well before the flight was due to depart, the company agent at Mabuiag Island endeavoured to warn the operator that the strip was wet and unsuitable for operations. This attempt to communicate failed due to a local fault in the Telecom system. The pilot was aware of a previous recent accident where a pilot landed short of the runway lip. When he arrived, he assessed the strip as suitable and landed well into the strip. By the time that he discovered that the strip was slippery, it was too late to go around. When it became obvious that he could not stop within the confines of the strip by using normal braking, he attempted a ground loop. The aircraft slid sideways off the end of the strip onto a beach.

Although the pilot was experienced in operating unpowered hang gliders, he had only limited exposure to powered versions. He had been conducting a short local flight, and subsequently advised that he had probably misjudged the landing flare. The aircraft struck the ground in a relatively steep nose-down attitude. The landing gear collapsed and the aircraft overturned before coming to rest on the flight strip.

The pilot had been conducting superphosphate spreading operations in the area two days prior to the accident and had completed approximately 60 trips during that operation. On the morning of the accident, he had just completed the sixth load when the outboard section of the right wing struck powerlines. The right wing was torn from its attachment points and separated from the aircraft. The aircraft then impacted the ground in a steep nose down attitude and came to rest 169 metres from the powerlines. A detailed examination of the aircraft and its systems failed to reveal any defect which could have contributed to the accident. The engine was operating at high power at the time of the impact. It is probable that the pilot forgot about the presence of the powerlines. It was noted that the pilot was not wearing a shoulder harness and that an unapproved modification had been made to the lap harness. The toggle fitted to the lap harness was a type approved for 9 to 12g applications only and therefore was not suitable for agricultural operations, which require equipment capable of withstanding 25g loads.

While performing a climbing turn to the left, at about 400 feet above the ground, there was a violent thud, a loud bang and the aircraft bank increased rapidly to the left. The pilot reduced power to reduce the level of engine vibration and levelled the aircraft. He noticed that a large portion of the left wing had been damaged before carrying out a successful, engine-off landing into a nearby paddock. An inspection of the aircraft discovered that the perforated, steel muffler core had been ejected into the propeller which flung the core into the left wing. The propeller, the aileron, two ribs and sections of the wing coverings were damaged. The above information was obtained from a report submitted by the pilot to the Australian Ultralight Federation. The report did not give the reasons for the failure of the muffler.

Circumstances:

The aircraft was taking off from a 920 metre grass strip in moderate to heavy rain. Take-off weight was about 60 kilograms below maximum authorised. Witnesses reported that the aircraft became airborne well beyond the normal position, and then only momentarily, before the pilot abandoned the take-off. The aircraft crossed the end of the strip and ran across a beach before coming to rest in chest deep water. The pilot of a following aircraft later indicated that there was a significant downwind component during the first aircraft's take-off attempt.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The take-off attempt was made in downwind conditions, for reasons which were not determined.