The airport and associated airspace were being operated in accordance with Mode 7 of the Sydney Long Term Operating Plan (LTOP), in that runway 25 was being used for departures while runways 34L and 34R were being used for arrivals.

A Boeing 737 (B737), registration VH-CZV (CZV), had departed runway 25 at Sydney. When the aircraft was 6 NM north-west of Sydney airport, the crew was cleared to climb to flight level (FL) 280. When it was 10 NM north of Sydney, the Departures North controller instructed the crew to turn right onto a heading of 060 degrees. Shortly after, the controller recognised that CZV was not going to reach 9,000 ft in sufficient time to maintain separation with another B737, VH-CZK (CZK), which was on a LETTI 3 Arrival, standard arrival route (STAR) for runway 34R and maintaining 8,000 ft. The required separation standard was either 1,000 ft vertically or 3 NM horizontally.

The aircraft were approximately 3 NM apart when traffic information was passed to the crew of CZV. Subsequently, the crew of CZV reported sighting CZK and advised the controller that visual separation could be maintained. Analysis of the radar data indicated that a breakdown of separation had occurred when the lateral separation standard was infringed while the vertical displacement of the aircraft was 500 ft. The aircraft subsequently closed to within 1 NM, at which point 1,400 ft of vertical separation existed. The investigation revealed that the controller cancelled restrictions for CZV that had been imposed for the departure. The speed restriction was cancelled first, followed by the altitude restriction of 5,000 ft.

The altitude restriction would have assured separation with the track of the inbound conflicting aircraft (CZK). When the altitude restriction was removed, the controller relied on monitoring the flight paths of the aircraft and his ability to implement any necessary action to maintain separation. The controller was undergoing a familiarisation period under the supervision of a suitably rated controller. The controllers were distracted, from the monitoring role, by coordination activities with flight service and the control tower. As a result of this investigation and a number of similar occurrences, the Bureau of Air Safety Investigation issued report B98/90 which covered the systemic investigation into factors underlying air safety occurrences in Sydney Terminal Area airspace.

After taking off from Scone, the pilot of an Embraer 820C aircraft reported that when retracting the landing gear, the landing gear selector failed to return to the neutral position, and the gear unsafe light remained on. The emergency checklist was actioned and the emergency hand pump was used by the pilot to extend the landing gear, however, the nose gear failed to lock down. The pilot requested emergency services to be in attendance prior to returning for a landing. When the aircraft subsequently landed, the nose gear collapsed during the landing roll. The pilot and passenger vacated the aircraft without injury.

An investigation revealed that the right engine driven hydraulic pump was leaking from a loose suction line fitting, and that most of the hydraulic fluid had been lost overboard. Inspection of the hydraulic hand pump found contamination of the check valve. This was probably enough to hold the valve off its seat so that insufficient pressure was available to lock the nose gear in the down position.

Further investigation determined that the right engine had been changed prior to the accident flight. As the engine had been supplied without a hydraulic pump, a serviceable pump was fitted. During engine ground running, the right hydraulic pump failed to pressurise the system and it was assumed that, because the left and right engines rotate in opposite directions, the pump was configured for left engine rotation. On completion of the engine run, the hydraulic pump lines were reconfigured for correct rotation. A very short engine run confirmed that the pump pressurised the system and that no leaks were apparent. However, the suction line had not been properly tightened, which was not detected. Sometime later, at about the time the aircraft departed, hydraulic fluid commenced to leak from the loose suction line fitting.

It is likely that whilst the pump was operating in the reverse rotation mode during the first engine run, the reversed hydraulic flow disturbed any sediment that was in the hydraulic system. The contamination then found its way into the hand pump when it was operated by the pilot during the emergency extension of the landing gear.

While returning to Adelaide from Moomba, the crew of a Dash 8 detected smoke coming from around the weather radar. They immediately turned off the equipment, donned oxygen masks and made a PAN call requesting RFF services to be placed on standby. To dissipate the smoke, the crew requested a descent to 10,000 feet where the aircraft was depressurised and the forward outflow valve was opened. After ensuring that there was no smoke or flame coming from the radar unit, the crew made the decision to continue to their destination and briefed the passengers accordingly. Upon arrival in Adelaide the aircraft made a normal approach and an uneventful landing. The flight attendants were later sent for medical attention due to the effects of smoke inhalation. Maintenance investigation by the operator traced the fault to the radar indicator unit. This was replaced and the aircraft returned to service.

CIRCUMSTANCES

VH-AZX, a Beech 76, was taxiing for take-off at the same time as VH-NJU, a British Aerospace 146. Both aircraft had made the appropriate mandatory broadcast zone (MBZ) calls. While lining up for take-off, the crew of NJU noticed AZX at taxiway E approaching the runway. The crew of NJU broadcast "rolling" and AZX stopped. Immediately, another voice broadcast that AZX had infringed the flight strip and suggested that the pilot should take off. This broadcast was acknowledged by the pilot of AZX, who taxied onto the runway and took off.

The crew of NJU had only just commenced the take-off roll and rejected the take-off. The other voice was that of the airport safety officer, who was in a vehicle near taxiway E. He saw AZX cross the holding point and enter the flight strip. He believed that the crew of NJU had not seen AZX, and that a dangerous situation existed. This was the basis for his radio transmission to the pilot of AZX. The investigation found that there were no published procedures or guidelines for airport safety officers to follow in situations perceived to require immediate action. On this occasion, the safety officer made a radio transmission which the pilot of AZX interpreted as an air traffic control instruction and which he subsequently followed.

SAFETY ACTION

The Bureau of Air Safety Investigation is currently investigating a perceived safety deficiency that has been identified as a result of this occurrence. The deficiency involves the lack of published information available to airport safety officers on recommended radio usage. This information is necessary in order to provide safety officers with phraseology they can use to alert pilots to safety hazards, without using terms that could be interpreted as controlling or suggesting. Any recommendation issued as a result of this investigation will be published in the Bureau's Quarterly Safety Deficiency Report.

FACTUAL INFORMATION

The pilot of the Cessna 206 was conducting repetitive parachute jumping exercises at the Dale River drop zone. He was operating in Class C airspace and communicating with the air traffic controller at Perth Approach on the radar advisory frequency. He advised his intention for the parachutists to jump and was cleared by the controller to operate to a ceiling of flight level (FL) 110. Soon after the pilot of the Cessna received his clearance to drop, the pilot of an Airbus A320 contacted Perth on the approach frequency, advising that he was on descent to FL120. The Airbus was inbound to Perth from the south-east on a track that passed close to the Dale River Drop Zone. The Cessna pilot reported that he had the Airbus sighted. The air traffic controller then assigned the pilot of the Cessna responsibility for maintaining separation visually from the Airbus but the Cessna pilot did not respond. Because the two aircraft were on different frequencies, the pilot of the Airbus was unaware of the Cessna and that the pilot of the Cessna had been assigned a requirement to remain visually clear of the Airbus.

At the time of the incident, the Cessna was tracking southbound and had just turned left with the Airbus passing about 1.25 NM to the North. The controller then cleared the Airbus to descend to 8,000 ft. As the Airbus left FL120 on descent, the crew received a traffic alert and collision avoidance system (TCAS) traffic advisory (TA) closely followed by a resolution advisory (RA) instruction to reduce sink rate with which the crew complied. The crew of the Airbus reported sighting the Cessna 400 ft below their aircraft and climbing. Radar evidence indicated that the nearest the aircraft came to each other was approximately 700 ft vertically and 1.25 NM laterally.

The Aeronautical Information Publication (AIP) Air Traffic Rules and Services (RAC) noted that air traffic control (ATC) will provide separation between instrument flight rules (IFR) and visual flight rules (VFR) flights. In this situation, ATC would have normally been expected to direct the aircraft such that a minimum separation of 5 NM laterally or 2,000 ft vertically between the aircraft was maintained. However, it also stated that "under certain conditions, the pilot of one aircraft may be given the responsibility for separation with other aircraft". The Manual of Air Traffic Services (MATS) section 8 prescribed the application of visual separation and there was no requirement for the pilots of aircraft that had not been assigned separation responsibility to be advised that visual separation standards applied. There was also no requirement for the aircraft to be on the same frequency.

Whilst Civil Air Regulation 163 stated that an aircraft must not be flown so close to another aircraft as to create a collision hazard, it did not prescribe a minimum separation requirement. Therefore, the pilot given the responsibility for maintaining visual separation was at liberty to fly close to another aircraft so long as no collision hazard was created.

Although the air traffic controller had assigned a visual separation requirement in accordance with the AIP and MATS, he had not sought confirmation from the Cessna pilot regarding the assignment of the separation responsibility. However, there was no evidence to indicate that the Cessna pilot did not maintain such separation from the Airbus. Because the aircraft were on different frequencies and the air traffic controller had not advised the Airbus pilot that the Cessna was assigned separation responsibility, the Airbus pilot was unaware of the Cessna and the reduced separation standard being applied. He had no opportunity to accept or reject the reduced separation standards and his first indication of the presence of the Cessna was the TCAS alert to which he properly responded.

SAFETY ACTION

In 1996, a similar event occurred involving a Boeing 767 departing from Darwin and a Partenavia P68C which was conducting aerial work at Darwin. As a result of the investigation into that incident, the Bureau issued interim recommendation IR970027 to Airservices Australia. The interim recommendation stated, in part, that "Airservices Australia should introduce a requirement for a controller to advise the crew of an IFR-category aircraft that the pilot of another aircraft has been assigned visual separation responsibility and to pass traffic information on the other aircraft". On 31 October 1997, the Bureau received a response from Airservices Australia which stated, in part, that "Airservices will seek a review, in conjunction with CASA, of the visual separation standards applicable to aircraft operating below FL125, at the earliest opportunity. On completion of the review, BASI will be advised of any outcomes".

Response classification: OPEN

As at 11 July 1998 the Bureau had received no further advice on the proposed review. As a result of this occurrence (9801510), the Bureau is investigating further safety aspects related to visual separation procedures and responsibilities. Any safety outputs resulting from this investigation will be published in the Quarterly Safety Deficiency Report.

FACTUAL INFORMATION

The crew of an instrument flight rules (IFR) Beech 200 (B200) was conducting a base check which would entail a practice non-directional beacon (NDB)/distance measuring equipment (DME) approach to runway 12 at Williamtown aerodrome. The pilot under check (handling pilot) and the checking pilot briefed for an approach to the minima, followed by a missed approach to 1,500 ft and then join the circuit for circuit training. The missed approach was to be conducted with the aircraft configured to simulate asymmetric operation. While inbound to Williamtown, the handling pilot briefed the approach controller of their intentions and was subsequently cleared to make the NDB/DME approach. The handling pilot then advised the approach controller that, after the NDB, the aircraft would conduct a go around. The check pilot did not hear this transmission due to the aircraft's communications configuration, which prevented his hearing any air/ground transmission by the handling pilot.

Prior to the missed approach point the handling pilot commenced an asymmetric missed approach and reported to the aerodrome controller. The aerodrome controller (ADC) instructed the crew to go around, to maintain runway heading and to maintain an altitude not above 500 ft. The transmission from the ADC was broken and both pilots believed that the assigned altitude was 1,500 ft. The handling pilot readback the requirement to maintain runway heading but did not readback the altitude, which was contrary to Aeronautical Information Publication (AIP) procedures. The ADC did not challenge the lack of the readback of the altitude by the pilot, which was contrary to air traffic control procedures.

The ADC's intention was to limit the altitude of the B200 to establish 500 ft vertical separation with a formation of Macchis that was entering the circuit via the initial point. The Macchi pilots had sighted the B200 as they tracked from the initial point and pitched into the circuit. During the missed approach, at approximately 1,200 ft, the B200 pilots saw the formation of Macchis pass from their left to right in front of and slightly below the level of their aircraft. The Macchi formation passed with approximately 200 ft vertical separation.

ANALYSIS

The misunderstanding by the handling pilot of the B200 in relation to a "go around" and a "missed approach", and the fact that the check pilot did not hear the transmission, created a developing situation that was appreciated differently by the two pilots and the ADC. The minima for the "missed approach" was 570 ft, whereas a "go-around" could have been commenced from a lower altitude.

While the radio transmission quality made communication difficult, the lack of radiotelephony discipline by both the handling pilot and the ADC ensured that the opportunity to resolve any misunderstanding was lost.

SIGNIFICANT FACTORS

1. The pilot of the B200 requested a "go around" instead of a "missed approach"

2. The check pilot could not hear the handling pilot's air/ground transmissions.

3. The pilot did not readback the requirement to maintain 500 ft to the ADC.

4. The ADC did not challenge the pilot to readback the altitude requirement.

The crew of a Fairchild Metro 23 aircraft report experiencing difficulty in maintaining directional control as they applied power during the take-off roll. The aircraft seemed to be sluggish in accelerating and was pulling to the left. The difficulty in controlling the aircraft was exacerbated due to the inadvertent deactivation of the nose wheel steering button on the left power lever.

This system had been checked during taxi and was confirmed as serviceable. The crew indicate that this switch was "on" at completion of the pre-take-off checklist but had somehow been released during the early stages of the take-off roll.

The crew detected that the left propeller had not released the start locks, resulting in asymmetric power being produced. A non-standard call made by the pilot not flying is reported to have delayed the crew's recognition of the problem. The crew were in the process of abandoning the take-off when the aircraft veered off the left side of the runway, stopping prior to the runway 10 T-VASIS. The crew taxied the aircraft back onto the runway, switched the nose wheel steering system "on" and taxied normally back to the hangar for maintenance investigation.

The aircraft was not damaged during the incident and all aircraft systems checked out as serviceable. The crew briefed themselves on aspects of the previous incident before departing on the planned flight.

During a property inspection prior to commencing spraying, the engine failed. The helicopter was about 700 ft above ground level at the time. The pilot attempted to dump the load by the electrical system, but this failed to operate. He was too occupied to operate the mechanical dump system.

During the subsequent landing, the helicopter rolled onto its side after a cross tube on one side failed. The failed area had been weakened by corrosion and there was evidence of pre-existing cracks. The engine crankcase was fractured, consistent with a connecting rod failure at no. 5 cylinder. Logbook records indicated that the engine had been over-sped some 200 operating hours earlier. A faulty canon plug had prevented the electrical dump system from operating.

As the aircraft reached approximately 20 kts during the take-off roll, no 2 engine failed. The take-off was rejected. No other damage to the aircraft was reported. The engine examination by the aircraft operator revealed that all first-stage blades had failed adjacent to their blade platforms. The damage was most likely caused by failure of blade No 35, which failed in high cycle fatigue emanating from the blade trailing edge. The operator experienced several similar failures previously. The engine manufacturer was aware of the problem and was undertaking corrective action.

FACTUAL INFORMATION

Inbound to Launceston from Cape Barren, the pilot of a PA-23, VH-JSB, requested a 32L VOR/DME approach. Because of conflicting traffic, air traffic services (ATS) instructed JSB to enter the holding pattern, to maintain 7,000 ft, and report turning inbound in the holding pattern. The pilot acknowledged the instruction, but proceeded immediately into the 32L VOR/DME approach, descending from 7,000 ft. He reported turning inbound, but ATS believed the 'Inbound' call referred to JSB being inbound in the holding pattern. The pilot continued to fly the published 32L VOR/DME pattern and positioned the aircraft to intercept the 319 degrees radial as prescribed on the DAP chart. Minimum altitude specified before being established on the 319 degree radial is 2,800 ft.

Meanwhile, VH-OZV, a PA-31, was in cloud at 3,000 ft, conducting an ILS approach to runway 32L at Launceston. A company pilot occupied the right seat on the flight from Flinders Island. When passing the NILE locator, 7.7 NM DME distance, at 3,000 ft, the aircraft entered a cloud break and the right seat pilot sighted another aircraft about 200m ahead. The flying pilot took immediate action to avoid the other aircraft which was subsequently identified as JSB. JSB continued the 32L VOR/DME approach, and ATS provided OZV with separation.

ANALYSIS

The final approach paths for the runway 32L ILS and runway 32L VOR/DME are slightly different, with the ILS approach requiring the 313 degrees inbound radial to be flown, and the VOR/DME specifying the 319 degrees radial. The inbound turn in the VOR/DME pattern is a right turn to intercept the 319 degrees radial, and this requires the aircraft to fly across the inbound ILS approach track. An aircraft flying a VOR/DME approach would normally be inbound by 8NM, which is almost adjacent to the NILE locator, which aircraft utilise on an ILS approach.

Altitude requirements in the two approaches are also similar. At a distance of 7.7 NM DME, the distance of the NILE locator, an aircraft on an ILS approach would be descending from 3,000 ft, and an aircraft on a VOR/DME should be at about 2,900 ft.

Although aircraft may be carrying out different approaches to runway 32L, they need to be treated as if they are flying the same approach, and ATS apply separation standards accordingly. If a pilot misunderstands an ATS instruction, potential exists for two aircraft to be in close proximity.

The pilot of JSB misunderstood the ATS instruction to report inbound in the holding pattern, to mean to report inbound in the VOR/DME approach. Because of this misunderstanding, he commenced the approach and descended below 7,000 ft without a clearance. This action placed JSB in conflict with OZV which had been cleared to carry out an ILS approach to runway 32L. The 'Inbound' call to ATS did not provide a warning of the developing situation, as ATS were expecting the call in the holding pattern.

ATS had advised the pilot of JSB that the instruction to enter the holding pattern was because of other traffic in the area, including some making instrument approaches. Although adequate information was transmitted by ATS, the pilot's decision to descend from 7,000 ft and carry out the VOR/DME approach he originally requested, indicated a loss of situational awareness.

Further investigation showed that four minutes before the breakdown of separation between JSB and OZV, VH-IAM, a PA31, had departed from Launceston for Flinders Island. IAM was held at 6,000 ft to maintain separation from JSB which was thought to have been at 7,000 ft. However, when IAM departed, JSB had descended from 7,000 ft. With JSB descending to the southeast of the VOR and IAM climbing to the northeast, there was probably no breakdown of separation, but there was no separation assurance.

SIGNIFICANT FACTORS

1. JSB descended from 7,000 ft and commenced a 32L VOR/DME approach without a clearance.

2. In a cloud break, the right seat pilot of OZV sighted JSB.

3. The flying pilot in OZV took action to avoid JSB.