The out-going controller stated that the runway configuration made the management of traffic complex, a situation which required a high level of concentration. She had spent approximately one and half hours on duty and felt ready for a break. Consequently, once the new controller commenced in the approach east position, she relaxed. However, she remained at the console monitoring the audio program for approximately another 10 to 15 minutes but did not maintain a full appreciation of the new traffic sequence. She provided only limited coordination assistance to the new controller.

When the Navajo was north-east of Perth, the approach east controller radar vectored the aircraft to separate it from the Baron and to position it for right base runway 03. This was in compliance with a local instruction that required inbound aircraft which would overfly the departure end of a nominated runway to be maintained above 4,000 ft or radar separated from departing traffic. After radar separation was established with the departing Baron, the pilot of the Navajo was instructed to descend to 2,500 ft. When the Navajo was approximately 20 NM east of Perth, the approach east controller elected to track the aircraft for runway 11. The Navajo was radar vectored on a heading of 270 degrees for a left circuit to that runway.

Shortly after, the approach east controller observed the secondary surveillance radar altitude readouts from both aircraft and determined they would pass without adequate vertical or horizontal separation. The pilot of the Navajo was instructed to maintain 3,000 ft, which provided 500 ft vertical separation from the Baron. This was less than the required vertical separation of 1,000 ft. The approach east controller also instructed the pilot of the Baron to turn right onto a south-easterly heading for separation. As the controller further determined that both the horizontal and vertical separation standards were not going to be maintained, he passed traffic information to the pilot of the Baron. The pilot of the Baron subsequently sighted the Navajo and monitored the flightpath of the other aircraft until it was well clear.

The two aircraft passed with less than 3 NM horizontal separation and less than 1,000 ft vertical separation. There was a breakdown in separation.

ANALYSIS

The Navajo was the second of three aircraft being sequenced for runway 03. The controller determined the Navajo might eventually conflict with following traffic and considered changing the aircraft to runway 11. However, a pending Airbus departure to the east from runway 03 would possibly have conflicted with the Navajo as it tracked downwind and thus it remained sequenced for runway 03.

When the Airbus from runway 03 was airborne, the controller reconsidered the earlier option of changing the Navajo to runway 11. Two larger and faster aircraft, following for runway 03, were closing and would require vectoring to maintain separation and spacing for landing. The controller decided to change the Navajo to runway 11. At this stage the Baron and Navajo were radar separated and assigned the same level. However, when the approach east controller turned the Navajo downwind for runway 11, he placed both aircraft on closing reciprocal radar headings without re-establishing vertical separation in accordance with local instructions.

The turn given to the pilot of the Baron was an attempt to maintain 3 NM separation. The controller was also aware that 500 ft was insufficient separation for IFR category aircraft but believed that under the circumstances it was better than having the aircraft at the same altitude. The provision of traffic information was appropriate and enabled the application of visual separation by the crew of one of the aircraft.

The out-going controller could have contributed more to assist the new controller in the period immediately following the handover/takeover. While the new controller would have appreciated the immediate disposition of aircraft on the radar display it takes some time to appreciate the plan for a developing sequence of air traffic. The basis of the handover/takeover and monitoring process is to ensure the out-going controller maintains the full disposition of aircraft and understands what actions are needed to manage and separate, immediate and pending aircraft until the new controller fully appreciates the disposition and sequencing plan of the control position. While the initial reaction of a controller to relax after handing over is understood, for an effective handover/takeover, all controllers at a control position should maintain a state of awareness commensurate with active controlling until the new controller indicates a complete comprehension of the traffic situation.  Perth Approach Control Centre does not have specific handover/takeover instructions for controller guidance.

During the investigation, aspects of the restructure of Perth airspace scheduled for implementation by December 1996 were provided. The restructure will provide track crossover points outside 30 NM and separation assurance procedures. While these measures will not necessarily alleviate similar occurrences, they should provide an airspace environment better able to cope with similar situations.

SIGNIFICANT FACTORS

1. The aircraft were required to pass on approximately reciprocal tracks due to the runway configuration.
2. The approach east controller did not use separation assurance techniques when there was a possibility the aircraft would conflict.
3. The out-going air traffic controller did not fully monitor the new traffic sequence and only provided limited assistance to the new air traffic controller.

SAFETY ACTION

The Bureau of Air Safety Investigation is evaluating controller handover/takeover procedures. Any forthcoming recommendation will be published in the Quarterly Safety Deficiency Report.

The pilot reported that the helicopter was being used to muster cattle. While manoeuvering at about 30 ft AGL and a speed of 10 knots the pilot said he heard a loud bang. He was able to conducted an immediate autorotative landing.

Post flight inspection found that the main rotor drive shaft flex plate had separated at the gearbox end. The flailing end had then cut into the fuel tank, as well as causing other damage in the area.

Specialist examination concluded that the flexplate failure was caused by fatigue crack growth. The fatigue crack initiated at a region of intergranular corrosion at the edge of the plate. The pilot reported that the failure occurred some 40.8 hours after the previous 100 hourly inspection. Because of the type of flexplate in use, a dye penetrant inspection had been conducted on the flexplate during that previous inspection. This was required by an Airworthiness Directive, which subjected all such flexplates to a special inspection every 100 hours until they were replaced by a new version of flexplate. A similar directive issued by the United States FAA required an inspection every 50 hours.

The pilot was positioning the aircraft from Adelaide Airport to Parafield where he was instructed to join the circuit on right base for a landing on runway 08L. When the landing gear was extended the nose gear down light failed to illuminate. The pilot initiated a go around and attempted to obtain a safe indication by recycling the gear using both normal and manual methods, but without success.

An inspection from the ground indicated that the nose gear leg was trailing about 30 degrees, which was verified by the pilot of another aircraft flying close by who advised that all the gear retracted normally, but the nose gear trailed when extended.

A decision was made to land the aircraft with the gear retracted to minimise damage.

An investigation revealed that the forward retract drive tube was severely bent, and the rear drive tube bowed. This prevented the nose gear from fully extending.

The reasons why drive tubes were bent could not be determined. The aircraft may have suffered a heavy landing on the nose gear, or it may have been extended very late on the previous landing, with the nose wheel contacting the ground just prior to the gear locking into the down position, bending the tubes, but still with enough energy to engage the down lock. The pilot who flew the aircraft previously denied any knowledge of an abnormal landing.

During a practice touch and go landing, the aircraft ballooned during the flare. The pilot applied some power to prevent a subsequent heavy touchdown/bounce and persisted with the landing attempt. She said that she was then distracted by the proximity of a runway strip marker on the left side of the aircraft. The pilot lost directional control of the aircraft, and a ground loop ensued.

At 0812, VH-CZL departed runway 16 at Melbourne on a 16 Cowes 5 departure with instructions to maintain 3000 ft. This departure involves tracking 170 deg until through 2500 ft or four miles DME and then tracking direct to Cowes which is on the Melbourne 150 deg VOR radial. After CZL made contact with departures control, the aircraft was cleared to climb to flight level 370.

At 0813, N61CF departed from runway 17 at Essendon heading 170 deg and initially limited to 3000 ft. At 0815 CZL left 5000 ft and N61CF was cleared to climb to 4000 ft. Shortly afterwards N61CF was instructed "at 4000 ft turn right heading 260 deg".

At 0816, N61CF was observed in a right turn and climbing through 4700 ft. At this time CZL was climbing through 5500 ft with N61CF less than two miles away and closing. N61CF was asked to confirm maintaining 4000 ft and passed traffic on CZL. The pilot of N61CF advised the traffic was in sight and apologised for the transgression.

The pilot was taxiing the aircraft for take-off at the time of the accident. He had just completed refuelling at the fixed fuel bowser and was turning the aircraft to the right when it collided with a refuelling cart that had been positioned to refuel a regular public transport aircraft that was expected to land shortly. The impact crushed a section of the wing's leading edge and then, as the cart rolled over it punched a hole in the lower surface of the wing fuel tank.

The cart had been repositioned by the fuel agent between the time the pilot completed refuelling and when he taxied the aircraft. The cart had not been there when he taxied in, and he was not expecting it to be there when he taxied out. The Glassair aircraft has a tailwheel, and forward visibility is partly restricted. The pilot was speaking to the crew of the regular public transport aircraft, to establish their intentions, as he taxied out and this probably distracted him. He also reported that he was not feeling well, and this may have reduced his concentration.

The aircraft was landing on a loose gravel surface runway with a crosswind from the left at 10 - 15 kt. During the landing roll the aircraft veered to the right and the pilot took corrective action in an attempt to return it to the centreline. The aircraft started to recover, but due to skidding on the loose gravel surface it was too late to prevent the right main gear leg from striking a runway flare unit made from steel bore casing welded to a steel base plate, standing 300 mm high, causing the gear to collapse.

The helicopters main rotor blades came into contact with a tree during a low-level fence inspection operation. The helicopter then descended out of control into a flooded river and submerged. The pilot and observer egressed safely from under the water.

The pilot reported that he had manoeuvred the aircraft to within about 10 metres of some tall trees beside the river, in order to give the observer the best possible view of a section of fence. At this point the helicopter yawed left and the main rotor blades struck a tree. Later the pilot said that he though the tail rotor blades may also have struck a tree. After the tree strike the pilot had insufficient control and was unable to prevent the aircraft descending sideways into the river.

The wreckage was not recovered from the river for several weeks, due to flooding and continuing torrential rain. Later examination of the wreckage did not reveal any pre-existing mechanical fault which may have contributed to the accident. The tail rotor assembly was found to be intact and attached to the boom. No evidence was found to indicate the tail rotor blades came into contact with the tree.

The pilot reported that he had accumulated about 6.5 hours flying for the day as well as having spent time on the ground on business at a number of locations. It had been very hot and turbulent throughout the day. He was relieved when he reached the Newman circuit and relaxed as the flight was nearly over. He joined the circuit on downwind and made a general downwind broadcast on MBZ frequency. The pilot thought he had completed the downwind checks correctly, but subsequent events indicated he had forgotten to lower the landing gear. During his finals checks he noticed that the landing gear lights were not illuminated but he assumed he had forgotten to turn the brightness back to the daytime setting. He realised the gear was still up when the propeller started to hit the ground. The landing gear warning horn, which had not sounded during the circuit, came on as the aircraft settled onto its lower fuselage.

The pilot reported that the landing gear waring horn may have been intermittent prior to the accident. He had made a note on the maintenance release to have it checked at the next periodic service which was due when the aircraft arrived back in Perth.

The pilot indicated that he felt that the factors leading to the accident were very straight forward. He was fatigued after a long day and had relaxed too much when he reached Newman. He had not payed sufficient attention to the operation of the aircraft and his fatigue had led to him rationalise the lack of landing gear lights as a rheostat setting rather than an indication the gear was still up. The failure of the landing gear warning horn to sound aggravated the situation.

FACTUAL INFORMATION

A Boeing 727 aircraft was en route from Melbourne to Brisbane via Casino and Coolangatta at flight level (FL) 350, while a Boeing 767 aircraft was en route to Brisbane from Sydney via BANDA and Coolangatta at FL370. The Boeing 767 was east of the Boeing 727's track and a few minutes behind on time estimates. There was a holding requirement at Brisbane with instrument landing system approaches in progress due to reduced visibility in passing rain showers.

The Brisbane sector radar position responsible for controlling the two aircraft was manned by a trainee controller undergoing final checks prior to rating. The trainee was being supervised by a current sector controller. However, the supervising controller was not the regular training officer for the trainee, and this was the first occasion that they had worked together. The Boeing 727 was initially vectored in a northerly direction for separation from other traffic but was shortly after instructed to turn right onto a north-easterly heading for arrival sequencing at Brisbane. The trainee controller intended to maintain the Boeing 727 on the north-easterly heading and provide a final heading to Coolangatta to meet the time required for sequencing. The Boeing 767 entered the controller's area of responsibility, and the crew requested descent to FL330 due to moderate turbulence.

The Boeing 767 was recleared to FL330. The new level was read back and the crew reported leaving FL370. The supervising controller discussed with the trainee the requirement to ensure separation between the two aircraft, since they were on converging tracks with the Boeing 767 crew cleared to descend through the Boeing 727's level. Discussion centred on whether the Boeing 767 should be radar vectored to parallel the track of the Boeing 727 until the required vertical separation of 2,000 ft was established. However, as there was more than sufficient horizontal separation (minimum separation required was 5 NM), the trainee controller elected to leave the Boeing 767 under the crew's navigation and to monitor the situation. The supervising controller believed it was reasonable to allow the trainee a level of latitude for independent action greater than he normally would for a trainee as the trainee controller had almost completed training. As separation between the two aircraft reduced to approximately 15 NM, the trainee controller's attention was diverted as he conducted coordination with another control position. As horizontal separation approached 8 NM and vertical separation was approximately 700 ft (with the Boeing 767 below the level of the Boeing 727) the trainee controller instructed the crew of the Boeing 767 to turn right onto a heading to parallel the track of the Boeing 727.

During this transmission the trainee controller incorrectly advised the Boeing 767 crew that the radar heading was for sequencing, instead of separation. The trainee controller requested the crew of the Boeing 767 to expedite descent and to confirm that the aircraft was turning right. The crew advised that the aircraft was turning right and expediting descent and, shortly after, reported sighting the Boeing 727 as horizontal separation reduced to approximately 4 NM with vertical separation of 1,600 ft. Horizontal separation reduced further to just over 3 NM before 2,000 ft vertical separation was re-established. The operating console was not fitted with an air-ground-air communication override facility to enable the supervising controller to intercede in trainee transmissions. Traffic information was not provided to either aircraft as the horizontal and vertical separation reduced to less than the standard. There was no Traffic Alert and Collision Avoidance System (TCAS) report from the B767. ANALYSIS The trainee's use of the term "sequencing" instead of "separation" did not provide the level of notice to the crew of the Boeing 767 that was warranted under the circumstances. Had the crew been advised that the heading change was for separation they may have been more expeditious in complying. However, the situation should not have been allowed to develop to the stage where immediate action was required to maintain separation.

Similarly, the inclusion of a console facility that would enable the supervising controller to override the trainee's transmissions to establish appropriate separation measures would have been beneficial. But again the situation should not have developed to the extent that such facilities were essential. Both controllers had discussed separation requirements for the two aircraft, and the trainee was satisfied with monitoring the situation. The supervising controller deferred to the trainee's judgement because he understood the trainee was close to achieving a rating. However, the trainee became distracted, and the supervising controller did not adequately monitor the trainee's subsequent control actions.

The supervising controller could have emphasised to the trainee the need to give priority to the radar display and to maintain a high scan rate to ensure separation. However, the situation would have been still totally dependent on the performance of the trainee and the supervisor. As the trainee became distracted by coordination to the detriment of control, the supervising controller was unable to intervene adequately, and separation was lost between the aircraft. Monitoring of the flight paths did not provide an adequate level of separation assurance. Early implementation of an altitude requirement or a radar heading (to parallel the track of the Boeing 727) to the crew of the Boeing 767 would have been an adequate separation assurance technique. Use of separation assurance techniques would have greatly improved the possibility of the two aircraft remaining separated.

SIGNIFICANT FACTORS

1. The supervising controller did not adequately monitor the trainee controller's actions or ensure that a suitable separation assurance technique were employed.

2. The use of inappropriate radiotelephony phraseology by the trainee controller did not impart to the crew of the Boeing 767 the need for expeditious compliance with instructions.

3. The lack of a communications override facility deterred the supervising controller from implementing timely remedial action.

SAFETY ACTION

The Bureau of Air Safety Investigation is continuing its investigation into the provision of adequate communications override facilities for air traffic control training officers. This is intended for all consoles where on-the-job training of air traffic controllers is likely to occur.