This was the first time the pilot of VH-WMK had flown to the Melbourne area and for departure he attended the Moorabbin Briefing Office where he submitted a Visual Flight Rules plan for a flight to Shepparton and Lightning Ridge. The flight plan indicated that in the Melbourne area the pilot would be operating outside controlled airspace, (OCTA). The area forecast included predictions of broken stratus from 800 feet to 2000 feet above mean sea level with showers/drizzle and visibility reduced to six kilometres in showers and 3 kilometres in drizzle. Fog patches were predicted until 1000 hours. Under visual flight procedures navigation by reference to the ground is considered impractical above broken cloud cover. After departure the pilot found he was soon over full fog/low cloud cover, and he had difficulty ascertaining his position. However, he was able to remain in clear conditions on top, cruising initially at 2000 feet. The aircraft was equipped with radio navigation aids. Although there were ground stations in the Melbourne area to which these aids could be tuned, the pilot had the equipment selected to the Mangalore aids which did not give him navigational assistance. Melbourne Airport was closed to aircraft operations due to poor visibility associated with fog. Because of this there were many regular public transport (RPT) aircraft holding at various locations and heights. Essendon Airport was open and some smaller RPT aircraft were diverting into Essendon for landing, in lieu of Melbourne Airport. As a consequence of the situation the Melbourne Approach Controller was very busy. Approaches for Essendon were via the Plenty Locator and the Essendon Instrument Landing System (ILS) for runway 26. One of the aircraft diverting to Essendon was the F27, VH-FNF. As this aircraft was passing the Plenty area at an altitude of 3000 feet, tracking west for the Essendon ILS approach, the crew noted a light aircraft pass underneath them, tracking approximately north. They were not concerned at the time as it was approximately 1000 feet vertically clear of them. Other aircraft were holding at altitudes above VH-FNF, in a racetrack pattern, with respect to the Epping Locator. This beacon is some ten kilometres north-west of the Plenty locator and the flight paths were such that the radar returns at times passed in the vicinity of the Plenty Locator. At times, this presented to the controller a cluttered radar screen in that area. A characteristic of the radar equipment was that false returns were displayed on the radar screen as primary radar paints. For varying intervals, two of these appeared on the Approach Controller's screen close to the time of the incident. To ascertain whether a return is in fact an aircraft, requires several time consuming checks. In heavy workload conditions such as existed at the time it is often impractical for a controller to carry out these checks. Track splitting of radar returns from aircraft had also occurred. Another problem for the controller was that the tracks of two aircraft holding at Epping was sometimes lost from the display. Another controller standing behind the Approach Controller saw an unidentified return emerge from the screen clutter, in close proximity to the returns from VH-FNF and the other holding aircraft. It was initially thought this may have been associated with track splitting of the images of one of the holding aircraft. Because the Approach Controller was busy, the unidentified return was followed on another radar screen. At 1009 hours when asked for a position report, the pilot of VH-WMK indicated he was unable to ascertain his position due to fog. VH-WMK was radar identified at 1009 hours, by that time the aircraft was exiting the Melbourne Control Zone (Melbourne CTR) near Yan Yean Reservoir. The pilot was provided with radar assistance until he was able to resume his own navigation in the Kilmore area. The Melbourne Radar equipment detects aircraft by two different methods. It may detect reflections of radar signals which bounce off the body of an aircraft. These are known as a primary returns. The other type of return is generated by transponder equipment on board an aircraft. A radar transponder is sensitive to radar energy and is designed to emit a pulse whenever it is so triggered. This electrical reply to the radar beam is known as a secondary return. VH-WMK was equipped with a transponder, however, on this occasion it had not been selected "ON". This aircraft was planned to operate outside controlled airspace (OCTA) and although not mandatory, there was a notam requesting pilots operating OCTA within coverage of the Melbourne Radar to have their transponder selected on Mode "C", Code 2000. Radar signals received at the Melbourne radar are recorded and a replay of these was made. It was determined from the radar replay that VH-WMK entered controlled airspace without a clearance and crossed 0.7 nautical miles in front of VH-FNF. VH-FNF was maintaining an altitude of 3000 feet at the time, and it is thought that VH-WMK was maintaining about 2000 feet. The radar recording did not show a return from VH-WMK until 47 seconds prior to that aircraft entering controlled airspace and 77 seconds prior to its crossing the path of VH-FNF. At the time of the unapproved entry of VH-WMK into controlled airspace the Melbourne Approach Controller was busy and had his attention focussed on another area. In the short time span between the entry of VH-WMK into controlled airspace and its passing under VH-FNF, it was not detected by the controller.

A large group of pilots were practicing for the forthcoming World Gliding Championships. There were a number of weak thermals in the area near the starting gate position, and there were several gliders in each thermal. The pilot of VH-FQS encountered a surge of lift and commenced to increase the angle of bank and pull up, achieving a climb rate of about 6 knots. Shortly afterwards, the canopy of this aircraft struck the wing of VH-KYF, which was at a climb rate of about 4 knots. The canopy was shattered, and the left flap of VH-KYF was broken in half. The pilots maintained control of their aircraft, and subsequently landed safely. Neither pilot had seen the other aircraft in the thermal prior to the collision. The competitive nature of the exercise and the large number of aircraft in the area combined to present an operational hazard to those involved.

Passengers were moving from the terminal building to the F27 past the parked helicopter. The helicopter crew were ready to start and taxi when possible. The helicopter pilot observed some of the passengers stop outside the terminal building to take some photographs so he elected to start and taxi away from the area. He felt that no danger was created. Advice from the Civil Aviation Authority indicates that the aircraft operator is responsible for the safety of its passengers between the terminal building and the aircraft and that they are not in a public area when on the tarmac.

Circumstances:

VH-EWS was departing from runway 16 at Sydney for Hamilton Island, followed shortly after by VH-YMK for Perth. The DEPARTURE Radar Controllers on duty at the Sydney Area Approach Control Centre (AACC), believed that a breakdown in the radar separation standard had occurred between the two aircraft shortly after take-off. The initial DEPARTURE instructions given to the Sydney Control Tower for VH-YMK were 'Cancel SID turn right heading 170 maintain 3 000'. The DEPARTURE sequence was subsequently changed twice with two aircraft VH-HVA and VH-EWS sequenced ahead of VH-YMK. Immediately following the issue of the final DEPARTURE instruction for VH-EWS, the instruction 'and YMK can be unrestricted' was passed by DEPARTUREs to the Tower. The Tower understood the instruction to mean cancel the previous DEPARTURE instruction, and the aircraft may now track via the cleared SID with no altitude restriction.

Significant Factors:

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

1. There was a breakdown in co-ordination between the Departures and Tower Controllers.

2. There was a different expectation and understanding of the departure instruction between the Departures and Tower Controllers.

Circumstances:

The pilot had been in the habit of flying about twice per month for a number of years. Each flight was about 30 minutes long and usually involved aerobatic flying. On this occasion the aircraft was observed conducting loops and a barrel roll in the normal area above 3000 feet above sea level. The aircraft later joined the circuit for a landing. While on the crosswind leg, the aircraft continued to descend until, at about 700 feet above ground level, the aircraft entered a gentle left turn. The nose dropped during the turn until the aircraft was descending at an angle of about 45`. When the aircraft was about 100 feet above the river the angle increased to about 85` nose down. No changes in engine power were heard during this time. The aircraft struck the Clarence River about 40 metres from the shore at an estimated speed of 180 knots. No evidence of pre-existing defects in the control circuits was found, however, the wings had been torn off on impact and large sections of the control circuits were not recovered. Witnesses reported that nothing was observed to fall off the aircraft and no part of the aircraft was flapping during the descent. Pathological examination concluded that the pilot had died as a result of myocardial ischemia (lack of blood supply to the heart). The pilot had been hospitalised some years earlier due to a heart attack. This had not been reported to the medical examiner during subsequent licence medical examinations. Hence, as the required tests had not been conducted during licence renewal, it was not possible to determine whether the pilot may have been able to hold a licence at the time of the accident.

Significant Factors:

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

1. Pilot did not report his medical history accurately.

2. Pilot suffered from coronary artery disease.

3. Pilot died during flight.

Both aircraft were tracking towards radio navigation aids at Biboohra from approximately opposite directions, and were the only aircraft using those tracks. VH-PCO's climb had initially been restricted to 4500 feet, to maintain separation with VH-TAK on descent. The controller responsible for separating the two aircraft became preoccupied with other traffic, and, overlooking the separation requirement, cleared VH-PCO to climb to 8000 feet and VH-TAK to descend to 6000 feet. VH-PCO had reached 8000 feet, VH-TAK had reached 7000 feet, and the two aircraft had passed before the mistake was realised. A breakdown in vertical separation standards had occurred in the vicinity of the radio navigation aids. However, the proximity of the two aircraft to one another at the time of passing was not established. The Cairns controller responsible for separating the two aircraft was performing an established traffic management function, which combines the dual responsibilities of Aerodrome and Approach control utilising a single radio communication frequency. This controller's workload at the time of the incident was subsequently assessed as being moderately high. Following this incident, emphasis was made on the requirement for air traffic control staff to process traffic within the limitations of the present air traffic control system, and in accordance with published standards and procedures. Additional traffic management procedures have also been instituted at Cairns, providing increased regulation of departing and arriving traffic. Other arrangements at Cairns are also being reviewed with the intention of making changes if appropriate. Matters under review include: the general management of airspace in the Cairns area; control tower management and staffing; and the adequacy of existing facilities.

Circumstances:

The aircraft was scheduled to conduct three round trips between Townsville and Cape Richards, with a stop at Orpheus Island on some legs, during the day. The pilot involved in the accident flew the first and third trips and another pilot flew the second. After the first trip the pilot reported that he pumped the floats out and considered that the quantity of water removed was normal. On the third trip he picked up a "standby" passenger at Orpheus Island. On arrival at Cape Richards the scheduled six passengers were loaded. A witness employed by the resort to handle the aircraft and passengers on the island reported that the floats appeared to be sitting in the water such that the water was above the normal water line on the floats. Examination of the aircraft loading indicated that the aircraft was overweight, and the centre of gravity was just inside the rear limit. The pilot reported taxiing at 1613 hours with eight persons on board. At 1624 hours he reported that he was returning to unload one passenger. In that time two take-off attempts into the north-east were made. The wind in the bay where the attempts were made was a light northerly. The pilot again reported taxiing at 1634 hours with seven persons on board. A further two take-off attempts were made. On the final attempt the pilot did not taxi as far into the bay as on previous occasions. The take-off was continued well out beyond the shelter of the island into an area where the wind was easterly at about 10 knots, and the swell was 1 to 1.5 metres. The pilot reported that the aircraft had attained an indicated airspeed of 55 knots, and he intended to fly it off the water at 57 knots. The right float had lifted from the water, and it hit a wave which pushed the right wing up. The pilot was unable to lift the left wing which hit the water, causing the aircraft to cartwheel.

Significant Factors:

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

1. The pilot selected the incorrect take-off direction for the wind conditions prevailing.

2. The pilot continued the take-off into an area of unsuitable swell. This accident was not the subject of an on-scene investigation.

After taking off in calm, fine weather conditions, the pilot climbed the aircraft to a height of about 500 above the ground and commenced a series of manoeuvres incorporating steep angles of bank. During the nose-down segment of a wing-over, the aircraft was seen to be near vertical and to accelerate rapidly before pulling up into a steep turn at about 200 feet above the ground. The turn was tightened to at least 60 degrees of bank, and shortly afterwards the right wing failed. The aircraft fell to the ground at high speed and collided with a fence post after sliding for 18 metres. The aircraft had been substantially modified by the pilot, and was being operated at well in excess of the design weight. The wing spar had failed as a result of the overload forces applied to the structure during the sequence of manoeuvres.

After a normal preflight inspection and takeoff, the pilot selected the landing gear up. The indicators were later checked and the pilot found that all the up lights were indicating normally, but one down light was also on. During the short flight the pilot operated the landing gear a number of times. He was satisfied throughout the flight that the landing gear was retracting; his only concern being whether the gear would extend again on his return flight. During the gear checking the aircraft arrived in the circuit area of the destination. The pilot made routine radio calls to his company and Townsville Flight Service, checked for boats in the landing area and noted that there were only four landing gear lights illuminated. On touchdown the pilot was unable to prevent the aircraft from pitching excessively nose down. The aircraft came to rest with the engine and some of the wings in the water. Subsequent actions by the pilot and a nearby boat resulted in the aircraft being righted and then towed to a mooring site. The landing gear had been in the down position for the landing. Since the landing gear indicating system uses four blue lights to indicate gear up and four green lights to indicate gear down, the pilot concedes that he had not noted the colour of the lights adequately in order to determine whether the gear was up or down.

The pilot flew to a private airstrip for a visit with fellow aviators. After about one and a half hours he decided to fly home. The aircraft took off to the north and climbed straight ahead to about 100 feet above the ground before making a steep, 180 degree, left turn and descending towards witnesses standing in front of a hangar. About 100 metres south of the witnesses the pilot commenced a left barrel roll from an estimated altitude 60 feet and an airspeed of about 85 knots. The aircraft managed to get over the top of the barrel roll but then descended rapidly. It impacted the ground in a south westerly direction with a nose-low, wings level attitude. It bounced off the ground and came to rest in about 10 metres with the engine dislodged from the airframe and the landing gear collapsed. It has been determined that the aircraft was serviceable prior to the accident. Neither the weather conditions nor the pilot's medical status contributed to the accident. Subsequent inflight checks in a Chipmunk aircraft have confirmed that a complete barrel roll cannot be achieved from an altitude of 60 feet with an entry airspeed of 85 knots. The pilot had been instructed and found competent to carry out barrel rolls at higher altitudes in his Chipmunk in 1966. He gave no prior warning that he was going to attempt to carry out a low level barrel roll.