The pilot was conducting practice solo circuits using runway 10. The wind was blowing from approximately 115 degrees at 15 knots. As he flared the aircraft to land, it ballooned. The pilot applied power to assist the touchdown, but the aircraft turned to the left, touched down and ran off the runway into a drainage ditch.

VH-MZX was inbound to Sydney from the north-west and had been given a clearance to descend to 3,000 ft. Thai International 986 (THA 986), which was outbound to the north-west, had just departed runway 34 at Sydney. The aircraft had been instructed to turn left onto a heading of 330 degrees and cleared to climb to 3,000 ft. Subsequently, THA 986 was turned onto a heading of 270 degrees. When the controller responsible for the control of THA 986 realised that both aircraft were at 3,000 ft, he instructed THA 986 to turn right. The closest point of approach of the aircraft was laterally 0.9 NM and vertically 200 ft. The required separation was either 3 NM laterally or 1,000 ft vertically. Control of aircraft in the terminal area at Sydney can be divided among up to four different controllers.

In some cases, it is necessary for aircraft under the control of one controller to temporarily enter the airspace of another controller. In such cases, it is normal practice for the aircraft to remain on one radio frequency under the control of the former controller. To assist with the processing of the aircraft, the controller responsible for each aircraft co-ordinates the passage of aircraft under his control with the controllers responsible for the adjoining airspace. This adds an internal co-ordination workload for any controller involved in this procedure.

On this occasion, VH-MZX was being controlled by the Approach (North) controller and THA 986 by a trainee Departures controller who was being supervised by a rated Departures controller. As THA 986 became airborne, the trainee controller asked the Approach (North) controller if he could vector and climb THA 986 clear of VH-MZX through the Approach (North) airspace. The Approach (North) controller concurred with his request. It was then the responsibility of the trainee Departures controller to separate THA 986 from VH-MZX. The trainee Departures controller believed that the inbound aircraft would only be cleared to descend to 4,000 ft and planned to vector THA 986 below this aircraft at 3,000 ft. This belief stemmed from the fact that this was the technique normally used by his training officer. The realisation that both aircraft were at the same altitude was delayed because the radar screen labels that indicate aircraft altitude had become cluttered because of the number and proximity of aircraft in the area. When the Approach (North) controller observed that the aircraft were in confliction he instructed VH-MZX to turn south.

The aircraft did not respond to the instruction. The pilot of VH-MZX later reported that he had not heard the callsign and the beginning of the instruction and was therefore unaware that the instruction was directed to him. He also advised that he had not seen the other aircraft until it was established in the right turn. This was probably because it was shielded behind a cockpit pillar. The controller supervising the Departures controller also had the expectation that VH-MZX would only descend to 4,000 ft. This expectation was apparently based on his normal technique but neither he nor the trainee had requested the Approach controller to limit the descent of VH-MZX to 4,000 ft. However, the supervisor believed that the trainee was going to vector THA 986 behind VH-MZX and by the time he realised that both aircraft were at about the same level the trainee had taken appropriate action to resolve the conflict and regain separation. The pilot of THA 986 saw the light aircraft as his aircraft was turned to the north and was satisfied that the aircraft were clear of each other.

Significant Factors

1. The airspace structure and air traffic control procedures applying in the Sydney Terminal area resulted in an unnecessary rise in co-ordination workload.

2. The control technique used by the trainee was inappropriate for the traffic disposition in the Sydney terminal area.

3. The Departures Controller did not monitor the techniques and instructions given by his trainee to the extent necessary to ensure adequate separation was maintained.

Safety Action

The division of airspace responsibilities within the approach/departures cell of Sydney AACC is to be changed following trials in the ATS simulator.

These "Structured Airspace" proposals should be implemented during 1994 and are expected to result in procedures whereby the internal co-ordination safety deficiency identified in this report will be alleviated.

The pilot reported that he had completed a number of flights into and out of Darnley Island during the day. When he was arriving at the island later in the afternoon, he found that the wind was calm and elected to land into the west to utilise the uphill slope. He considered the influence of the low sun on his vision and accepted the situation. He retracted the flaps on touchdown and commenced normal braking.

After realising that the brakes did not appear to be very effective, he applied heavier braking. The aircraft seemed as if it would run off the end of the strip, which had a 50-foot drop at its end. The pilot initiated a ground loop. While the aircraft was sliding sideways the landing gear collapsed. The aircraft came to rest off the side of the strip near the escarpment.

The strip length is reported to be 500 m. The performance charts indicate that the strip length required for this landing was of the order of 560 m.

The pilot forgot to select the landing gear down before landing and the aircraft touched down with its gear retracted. The pilot reported that he was under a number of pressures which may have contributed to his forgetfulness. His sleep the night before the accident was disturbed and he had accumulated a delay in his tasking during the progress of several flights prior to the accident landing. One of the passengers on the accident flight was a high-profile local identity.

His presence may have influenced the pilot's decision to continue the approach to landing after finding that the approach was faster and higher than normal. The landing gear warning horn did not sound because the warning horn circuit breaker had been pulled by the pilot. The pilot had developed this habit whilst flying in another aircraft where the warning system was operating incorrectly.

Earlier in the day, the C99 had flown from Port Macquarie to Sydney via Kempsey. The aircraft was on the first sector of the return flight. Before taxying the aircraft was issued with a 16 West Maitland Two departure clearance, at 9000 feet. The Captain was the handling pilot. The B767 was inbound to Sydney for a landing on runway 16 and was manoeuvring to remain clear of a line of weather east of the coast. The aircraft was under the control of Sydney Approach and was cleared to descend to 6000 feet. Cloud formations east of the coast between the 030 radial and 090 radial of the Sydney VOR, ranging between 10 and 15 miles, were generating clutter on the Sydney air traffic control radar.

Aircraft departing from runway 16 were requesting clearances to avoid the weather east of the coast. When the C99 pilot reported ready for take-off, an amended departure clearance was issued. The standard instrument departure clearance was cancelled and the aircraft given an initial heading of 100 degrees. After take-off, when contact was established with Sydney Departures, a climb restriction of 5000 feet was issued. This clearance limit was read back correctly and set in the assigned altitude indicator by the handling pilot. The aircraft was not fitted with an altitude alert system. After crossing the coast, the Captain asked the First Officer to request an immediate left turn as cloud build ups were visible about 2 miles ahead of the aircraft.

Sydney Departures cleared the C99 to turn left onto 030 degrees and soon after, for a further left turn onto 010 degrees. After advising the Captain, the First Officer selected a company radio frequency to pass details of their departure and estimated times of arrival. Whilst occupied with this task the First officer neglected to alert the Captain when the aircraft was 1000 feet from the assigned altitude, as required by company procedures. The Captain, who was not adequately monitoring altitude, did not realise this check was missed and climbed the aircraft through 5000 feet. The First Officer queried the altitude when he noticed the aircraft climbing above 6000 feet.

Simultaneously, the Sydney Approach controller noticed a reading of 6400 feet on the radar display of the C99. Due to the proximity of the weather returns, the label for that aircraft was obliterated by the weather return and was seldom readable. The Approach controller immediately advised the Departures controller who in turn asked the aircraft to confirm maintaining 5000 feet. The First officer advised it was not and that the aircraft was on descent to 5000 feet.

Both controllers recognised the separation standards were breached and issued instructions to both aircraft to regain separation. VH-OXE was instructed to continue climb and turn right onto 030 degrees by Sydney Departures. The B767 was instructed to turn left onto 270 degrees and to maintain 6000 feet. VH-OXE was also advised of the relative position of the B767. When the C99 climbed above 5000 feet, the minimum 1000 feet vertical separation standard with the B767 no longer existed. The minimum required lateral separation was 3 miles. The actual lateral separation was reduced to about 1.5 miles.

The pilot elected to use a short field take-off technique to ensure that the aircraft cleared a termite mound alongside the direct take-off path. The hot day and the sandy strip surface combined to lengthen the take-off roll required. The aircraft deviated towards the termite mound during the take-off run, and the pilot was forced to rotate at a lower-than-normal airspeed.

As the aircraft passed over the termite mound in a high nose up attitude, the tailplane struck the mound causing substantial damage to the tip of the tailplane and the elevator. The pilot did not associate the slight bump felt with mound contact. No adverse flight characteristics were noticed during the short flight to the destination. The damage was observed, by the pilot, during the after-flight inspection.

The left engine suffered a 5 second power interruption while the aircraft was cruising in moderately heavy rain. Following the power interruption the engine continued to operate normally. This was one of a series of similar events that led to the manufacturer undertaking instrumented and filmed flight tests. These disclosed that ice was building on the engine inlet and when released was being ingested into the engine.

Further testing found that the inlet heating cycle was being interrupted by electro-magnetic interference in the de-icing controller. This allowed ice to build up. Two modifications were introduced. SB F50-71-037 rerouted the bonding cable for the oil cooling flap actuator to reduce EMF transmission and SB F50-71-041 enlarged the lower cowl bypass duct to allow any displaced ice to eject overboard rather than through the engine. The operator has embodied both modifications and to date has not had a recurrence of power interruptions.

The pilot landed on the bush strip after a short local flight. After the aircraft had touched down and was decelerating along the strip, its nosewheel struck a small hole and a rock, causing the wheel to break up and the nosewheel support structure to collapse.

The pilot was conducting a test flight as part of the certification process required by the Civil Aviation Authority. Positive gear down and locked indications were obtained during the downwind leg of the circuit. As the aircraft touched down the pilot detected a settling of the right main landing gear and elected to go around. Inspection from the ground confirmed that there was a fault with the right landing gear. The pilot adjusted his approach so that the right gear touched down at a low speed. The gear leg collapsed on touch down and the aircraft slewed off the runway. It has not been determined why the landing gear collapsed.

The aircraft was engaged in spraying cotton crops. At the commencement of the third run, the aircraft contacted the ground with the main landing gear and bounced back into the air. The spray run was completed after which the pilot was advised by his marker that the landing gear appeared to be damaged. This damage was confirmed by the pilot of another company aircraft, which was operating in the near vicinity.

The pilot continued with the treatment of the cotton crop until his load of chemical was exhausted, upon which the aircraft was flown to Narromine where, after a further assessment of the damage by a ground observer, emergency services were called out for the landing. During the subsequent landing on a grass strip, both main landing gear legs collapsed.