The pilot was conducting a bore inspection at a height of approximately 300 ft above ground level at the time of the occurrence. He had just flown over the No. 7 bore when the engine started to run roughly. The pilot completed a magneto function check which did not disclose any problems. He decided to turn the ignition switch off and then back on to make the engine backfire in an attempt to clean any lead off the spark plugs. When the pilot attempted to turn the switch back on, instead of the key turning in the ignition, the whole ignition box turned in the dash, leaving the key in the off position. The pilot applied additional pressure to the key and the whole switch became detached and fell inside the dash as the key came out in his hand. He attempted, briefly, to correct the problem, then realising that he was going to have to land the pilot transferred his attention to the emergency landing.

The pilot aimed the aircraft between two trees knowing that the wings would be damaged, but hoping the fuselage would be safe. The aircraft went between the trees then skidded for about 10 metres before the propeller dug into the ground and it flipped over onto its back.

The aircraft had flown approximately 95 hours since its last periodic servicing and there had been no indications that the ignition switch mountings were faulty during that period. The reason for the rough running was not determined.

The pilot of VH-UBM called Wagga Tower inbound at 45 miles on the 065 radial of the Wagga VOR, at 8000 feet. He was instructed to maintain 8000 feet and track inbound on the 075 radial. The assigned track was to ensure separation was maintained with VH-SBA, which was tracking outbound on the 053 radial, initially at 7000 feet.

Once VH-SBA had passed the lateral separation point for the two tracks, at 10 miles from Wagga, the aircraft was cleared to climb above the level of VH-UBM. Although separation was arranged by procedural means by Wagga Tower, VH-UBM was observed on radar by Melbourne air traffic control crossing the 050 radial from south to north. A loss of procedural separation occurred due to VH-UBM being off track to the north of the 075 radial.

The pilot of VH-UBM made an error in mentally orientating himself with respect to the Wagga VOR and turned right instead of left. In retrospect he was uncertain of how this occurred.

Significant Factors

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

1. The pilot made an error in orientating himself with respect to the Wagga VOR.

2. The precise reason for this happening was not determined.

After the aircraft suffered a power loss at 1000 feet AGL, the pilot commenced an autorotational descent. The aircraft was flared above trees and the aircraft fell into a clearing.

A post flight inspection by the pilot found that the fuel system was contaminated by water. He had refuelled out of a 200-litre drum on the previous night and had omitted to carry out preflight fuel drains.

The pilot reported that while on approach to a three foot hover, he commenced a right turn to position the aircraft for refuelling. As he did so an unsecured object in the cockpit shifted, preventing movement of the cyclic control to the left. The pilot tried to recover the situation by increasing altitude, but the aircraft continued to roll right until the main rotor blades hit the ground. The aircraft was then thrown back onto its skids after which it rolled onto its left side.

VH-HYG departed Melbourne (ML) for Perth (PH) tracking ML - Yarrowee (YWE) - Q23 - CRENA cleared to climb to flight level (FL) 350. At approximately 20 nm from ML, VH-HYG was recleared direct to CRENA. VH-HYG contacted the Inner West (IW) radar controller 30 nm outbound from ML.

VH-HYA contacted the IW controller 120 nm inbound to ML, tracking from Mount Gambier (MTG) direct ADAMS - ML on descent to FL 210.

The controller was aware of the potential conflict with the tracks and the traffic disposition. He determined that both aircraft would pass with at least six miles separation and, in his judgement, would also have established vertical separation.

When the aircraft were approximately 10 nm apart (nose to nose) the outbound aircraft, VH-HYG, appeared to turn approximately 10 degrees to the right, towards the track of VH-HYA. The controller observed this but assessed that both aircraft would still pass abeam each other with minimum allowable lateral separation of five miles.

Both aircraft entered an area of potential separation conflict at approximately 60 nm from ML. Lateral separation reduced to 3.5 nm with no vertical separation.

The controller had used his experience to assess current/future positions of both aircraft but had failed to alter his plans to ensure separation after VH-HYG altered track. At the time of the loss of separation, the controller did not pass traffic information to either aircraft because of lack of time and because from the 3.5 miles nearest proximity the aircraft tracks began to diverge.

Significant Factors

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

1. The controller failed to alter his plans to ensure separation standards were not infringed after VH-HYG turned approximately 10 degrees towards the track of VH-HYA.

SAFETY ACTION

Since this incident, the CAA has reminded all inner sector controllers of the importance of:

1. Separation assurance; specifically, that profile separation is not separation assurance.

2. Radar technique and the action required when using minimum radar separation.

The pilot was conducting circuits and landings to gain additional experience on the aircraft type. He had already flown three circuits and had experienced some difficulty remaining behind slower traffic. On the fourth circuit, the Tower advised him to turn inside a slower aircraft ahead which caused a shortening of the downwind leg of the circuit.

Because of the number of aircraft operating in the circuit the pilot decided to discontinue the flight and advised the Tower he would make a "full stop" landing. However, due to the distraction of other traffic and concentrating on slowing the aircraft for landing, the pilot forgot to extend the landing gear.

The aircraft slid to a stop on runway 29 Left, sustaining damage to the underside and propeller.

The B767 was maintaining FL280, enroute from Denpasar to Singapore. As the aircraft approached SUMBU, at the junction of the A576 and W18 airways, the crew received a traffic alert from the aircraft's Traffic Alerting and Collision Avoidance System (TCAS). The crew checked the sector indicated by the TCAS and sighted another aircraft in their 2 o'clock position, at a range of about five miles. At the same time, the TCAS issued a resolution advisory "climb" command.

The captain climbed the aircraft as directed and the other aircraft passed about 200 feet below them. After several requests to Jakarta Control, the conflicting traffic was identified as a B737 enroute from Banjarmasin to Jakarta, also maintaining FL280.

FACTUAL INFORMATION

When the pilot of the Boeing 727 requested a taxi clearance from bay two for runway 17, the Aerodrome Controller (ADC) issued a clearance to the Surface Movement Controller (SMC) for the Boeing to cross runway 12. The SMC cleared the Boeing to taxi and issued the clearance to cross runway 12.

Other traffic requirements then became the priority for both the SMC and Co-ordinator.

While the SMC was issuing the Boeing 727 pilot with the clearance, the Cessna 152 pilot reported ready for take-off to the ADC. As both aircraft were on different frequencies, neither pilot heard the other. After a short delay, the Cessna was cleared for take-off.

Over the 30 seconds following the issuing of the take-off clearance, the ADC became involved in the co-ordination of three other aircraft. He then noticed that the Cessna had not taken off and reissued the take-off clearance. The Cessna pilot replied, 'We've got the 727 crossing'. At this point the ADC saw the Boeing crossing the runway and instructed the Cessna to hold position.

The second ADC was involved in discussions with surveyors during the entire sequence.

Due to the weather conditions, runway 17 was designated for arrivals and departures, while runway 12 was used for circuit traffic. This runway configuration is not often used in Canberra.

ANALYSIS

The ADC forgot that he had issued the Boeing with the clearance to cross. He was distracted by the presence of visitors in the tower and the busy workload.

The non-standard runway configuration may have had some influence on the ADCs procedures, resulting in a runway scan different to that which he normally would use.

FINDINGS

1. The ADC issued the SMC with a clearance for the Boeing 727 to cross runway 12.
2. The SMC issued that clearance to the Boeing 727 pilot.
3. The ADC issued the Cessna 152 pilot with a take-off clearance from runway 12.
4. The Cessna 152 pilot reported holding while the Boeing 727 crossed the runway.

SIGNIFICANT FACTORS

1. The runway configuration was not standard for Canberra.
2. The ADC was distracted due to a busy workload and the presence of visitors.

The duty runways at Perth were 06 and 03 for departures and 03 for arrivals. There were a number of aircraft inbound, including G-BNLW. Only one, VH-NGA, was taxiing for departure when a wind change occurred necessitating a change of runways. Following coordination between the tower, the approach east controller, the approach procedural controller and the flow controller, the duty runways were changed to runway 21 for departures and runways 21 and 24 for arrivals. During this coordination, the flow controller questioned the need for the change, advising that they had a sequence of seven aircraft (being sequenced for runways 03/06).

After the runway change was effected G-BNLW was advised of the change and to expect vectors for an ILS approach to runway 21. G-BNLW was inbound to Perth from the west and at the time of that advice had about 30 track miles to run. The aircraft was under the control of the approach west controller. VH-NGA was permitted to continue taxiing for runway 03, even though the aircraft was at a position where it would have been just as convenient to taxi for runway 21. Shortly afterwards G-BNLW was given a heading change to position for a runway 21 ILS approach and advised there was 25 to 26 track miles to go.

On departure, VH-NGA had planned to track to the southeast and would therefore be under the control of the approach east controller from shortly after take-off. This controller was responsible for separating VH-NGA from G-BNLW on the ILS approach for runway 21. It was his plan to have VH-NGA make an early right turn after take-off and have the aircraft established on an assigned radar heading (120 deg) prior to the three mile radar separation standard between the two aircraft being infringed.

As G-BNLW got closer, the approach east controller realised that for his plan to work, it was necessary for VH-NGA to get airborne without delay.  This was evidenced in transmissions to VH-NGA while still taxiing including requesting "minimum delay due inbound traffic", "will this be a rolling take-off" and "clear for immediate take-off". Although the approach east controller intended that VH-NGA make an early right turn, he never communicated this to anyone and therefore it was never communicated to the aircraft. VH-NGA made an intersection departure which further reduced the distance between VH-NGA and G-BNLW.

When VH-NGA became airborne, it was obvious from the radar return that the aircraft was not making an early right turn. The approach west controller was still controlling G-BNLW and he realised there could be a loss of separation between the two aircraft unless some preventive action was taken. At this time G-BNLW was intercepting the runway 21 localiser from a heading of 180 deg and was cleared to descend to 1500 ft.

The approach west controller instructed G-BNLW to continue its right turn onto 290 deg but the response from the pilot was "we're fully established now on the ILS". The controller repeated the instruction but again G-BNLW did not comply. The controller did not tell G-BNLW the reason for his instruction. By this time, it was evident that VH-NGA had commenced its right turn so the approach west controller did not persevere any longer in trying to get G-BNLW onto a westerly heading. He then instructed G-BNLW to contact the tower.

Shortly afterwards, VH-NGA contacted the approach east controller airborne and reported ".....right turn 120 climbing 3000 passing 2000". The controller responded asking the aircraft to make a hard right turn. It was estimated that separation between the two aircraft reduced to approximately 1.75 miles with less than 1000 ft vertical separation. The required standard is three miles when there is less than 1000 ft vertical separation.

Analysis

When the change of runways occurred, VH-NGA was taxiing in the vicinity of the terminal. It was not necessary for the aircraft to continue to be processed for a runway 03 departure. Had the aircraft been redirected to runway 21 then this incident would never have occurred.

There was no evidence from the recorded communications or interviews with the controllers involved of any consideration being given to reclearing VH-NGA for a runway 21 departure. It appears that the aircraft was simply permitted to continue taxiing for runway 03. This indicated a lack of consideration/coordination in respect of the departure for VH-NGA.

With VH-NGA processed for a runway 03 departure, the approach east controller accepted responsibility for separation between VH-NGA and G-BNLW. In doing so, he did not then apply any positive measures to ensure that separation was maintained. His plan was simply an expectation that VH-NGA would be on a diverging radar heading before radar separation was lost. This was a misjudgement which made no allowances for anything going wrong such as radio failure or an aircraft malfunction.

When the approach west controller became aware of the deteriorating separation situation between the two aircraft, he issued heading instructions to G-BNLW (i.e. continue the right turn onto 290 deg) which were meant to maintain separation. However, the intent of the instructions were obviously not understood by the crew of G-BNLW because the aircraft did not comply. This lack of compliance was most probably due to the lack of alerting phraseology (e.g. due opposite direction traffic continue the right turn onto...) to convey the urgency of the situation.

Factors

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

1. A runway change occurred at Perth airport from runways 03 and 06 to runways 21 and 24. As a result an inbound Boeing 747, G-BNLW, was vectored for an ILS approach to runway 21 while a taxiing Westwind, VH-NGA, was allowed to continue for an opposite direction departure from runway 03.
2. Although it would have been a simple matter to redirect VH-NGA for a departure from runway 21, for reasons not determined this was not done.
3. With the decision made to depart VH-NGA from runway 03, the approach east controller, who was responsible for separating that aircraft from G-BNLW, did not take adequate measures to ensure that separation.
4. The approach west controller, who was controlling G-BNLW, saw the loss of separation developing and issued heading instructions to G-BNLW to alleviate the situation. However, because he did not use appropriate phraseology to convey the urgency of the situation, his instructions were not followed by the aircraft.

The helicopter was engaged in mustering operations. On board was the pilot and one passenger. The pilot reported that the helicopter was "in near hover" at approximately 200-250 ft AGL, when he noticed a loss of engine power and the low rotor siren sounded. He was able to advise a second helicopter involved in the operation of the emergency by radio. The aircraft descended to land heavily, before coming to rest on its side.

Both the pilot and passenger sustained serious back injuries in the accident.

The engine was later test run, with no problems evident.

Windy conditions were reported to have existed at the time of the accident.