VH-NJL was maintaining flight level (FL) 240 on a flight from Cairns to Alice Springs and the crew had reported their position to air traffic control at BIDEB at 1537 EST estimating GAFER at 1619.  The crew also made a request for climb to FL 280 at this time.

The air traffic controller denied this request and explained that climb would be subject to a sighting and passing of an opposite direction BAe146. The time of passing was expected to be 1540 and the controller instructed both crews to report sighting and passing each other.

VH-JJU was maintaining FL 250 on a flight from Alice Springs to Cairns and reported passing GAFER at 1510 with an estimate for BIDEB of 1545.

At 1541, the crew of NJL reported their distance from Mount Isa as 38 DME. The crew of JJU immediately reported that they were 28 DME Mount Isa.  The controller acknowledged these reports and cleared NJL to climb to FL 280.

The captain of NJL had not seen the other aircraft and did not climb his aircraft, instead he queried air traffic control stating that he was now 35 DME and the other aircraft had just reported 28 DME.

The controller then asked both crews to report their DME distances from Mount Isa again.  Before this could be carried out, the crew of NJL reported sighting and passing JJU at 34 DME Mount Isa.  The crew of JJU then reported that they had sighted and were passing NJL.

With this information recorded, the controller again cleared NJL to climb to FL 280.  The crew acknowledged and reported leaving FL 240.

As NJL did not leave FL 240 prior to the mutual sighting and passing, no breakdown in separation standards occurred.

The controller would have required the two aircraft to have passed by 10 DME in order to approve a climb for NJL if a mutual sighting and passing was not achieved.  It is probable that, on hearing the initial DME reports 10 NM apart, the controller's mind set about this standard led him to think that the aircraft had passed by that distance.  In fact, they had not yet passed.

Traffic levels at the time of the occurrence were high and complexity increased by virtue of several weather diversions by aircraft under his control.

Findings

1. Both aircraft were operating at approved levels at the time of the level change request by the crew of NJL.
2. The time of passing calculation by the air traffic controller was sufficiently accurate for control purposes.
3. The controller most probably misinterpreted the DME reports of NJL and JJU to indicate a passing of the aircraft by 10 NM when, in fact, they were 10 NM prior to passing.
4. The air traffic controller issued a clearance for NJL to climb to FL 280 when the appropriate separation standard did not exist.
5. The crew of NJL did not initiate the approved climb due to their assessment of the position of the other aircraft.
6. The two crews subsequently sighted and passed each other.
7. There was no breakdown in separation standards. 

Significant Factor

The air traffic controller was busy at the time of the occurrence and misinterpreted the information available to him.

Runway 34 was in use and the wind was from 340 degrees T, at 15-25 knots. VH-HYJ, an A320 aircraft, commenced the take-off roll from the Juliet taxiway intersection. The aircraft was climbed on a track of 340 degrees M until about three miles from the airport, then was turned left onto a track of 230 degrees M.

VH-TJH was also cleared for take-off from the Juliet taxiway intersection. At the time of this clearance VH-HYJ had passed the threshold at the departure end of the runway. VH-TJH was also flown on a track of 340 degrees M on climb. At a height of about 1800 feet the aircraft encountered severe wake turbulence from VH-HYJ. To maintain control and prevent the aircraft from rolling excessively the captain was forced to apply and hold almost full left aileron followed by a significant amount of right aileron over a period of approximately 20 seconds.

At the time of the incident VH-TJH was about five kilometres behind the other aircraft. The longitudinal separation between the two aircraft, at the time the take off in VH-TJH was commenced, met the minimum standard specified in the Manual of Air Traffic Services.

Significant Factors

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

1 Encounter with wake turbulence.

VH-LRT was on a visual flight rules (VFR) flight from Riddell via Albury to Bankstown and cruising at 7500 feet. The pilot was having difficulty with visual navigation due to cloud cover and as a result the aircraft entered the Wagga control area steps without an airways clearance.

VH-CMH was on climb out of Wagga for Sydney when the crew saw LRT on a converging heading and estimated it was 500 ft to 700 ft below. The crew of CMH reported that there was scattered to broken cloud from 1500 ft to flight levels. They reported the intruding aircraft to Wagga tower. The tower controller in turn checked with the Melbourne sector eight radar controller who advised there was an unidentified aircraft painting at 7500 ft 25 miles to the northeast of Wagga. That aircraft was duly identified as LRT, the offending aircraft.

LRT had previously transgressed twice on the trip from Riddell, on one occasion entering controlled airspace, climbing through 10,000 ft without a clearance and on the second occasion leaving a cleared altitude without a clearance while transiting Albury control area steps. For this reason, the Melbourne sector eight radar controller had been monitoring the aircraft's progress but had lost radar contact when the aircraft was to the south of Holbrook.

The radar tape was monitored and revealed that a code 2000 return appeared on radar about 16 minutes later at a position 15 miles south of Wagga at 8400 ft on a northerly track entering Wagga CTA. It was later determined that this return was LRT. The tape showed that LRT proceeded in a north-north-easterly direction through Wagga CTA and gradually descended to 7000 feet when, at 15 miles northeast of Wagga, the two aircraft were one mile apart at the same altitude.

Factors

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

• The pilot of LRT was not competent to navigate his aircraft in the cloud conditions existing at the time. This resulted in the aircraft entering the Wagga CTA without a clearance and because the Wagga air traffic controllers were unaware of LRT, they had not arranged separation with CMH.
• The Melbourne sector eight controller had been watching LRT, because of earlier incursions, until its return disappeared from radar. Although Wagga airspace is not the responsibility of the Melbourne sector eight controller, it is considered that in this instance when the code 2000 return appeared entering Wagga airspace, the sector eight controller should have suspected that it may be LRT and alerted the Wagga controllers accordingly. Such an alert should have resulted in this incident being avoided.

The helicopter had been engaged in a low-level survey for approximately four hours. As the pilot commenced to climb at 60 kts to return to the helipad for refuelling, he saw a single-strand powerline, at an oblique angle, about 30 ft in front of the aircraft. In an attempt to avoid the wire, the pilot rolled the helicopter to the right and pushed the nose down. However, a loud bang was heard, and the aircraft yawed to the left. The pilot centralised the controls, transmitted a MAYDAY call on the company frequency, and informed the passengers to prepare for a forced landing. He successfully carried out a flat approach and "run-on" landing in a nearby clearing. At the time of the accident the weather was fine. The pilot described the visibility as good, with the position of the sun approximately overhead.

A damage inspection of the aircraft revealed slash marks on the main rotors consistent with those of a wire strike. The powerline had sliced through the upper left cabin area, and the arm of a winch located above the left passenger door had been pulled and twisted. The wire appeared to have temporarily wrapped around the exhaust before unravelling and falling clear.

The pilot reported he had been notified of the task the day before, and as part of his flight planning routine, had consulted local employees from his company. Although he had flown in the same area some months before, he had not seen the powerline, and nobody he spoke to appeared to have any knowledge of its presence. Whilst a general survey of the area was carried out in preparation for the flight, the pilot advised he was not able to complete a high-level reconnaissance due to the nature of the operation.

The pilot had accumulated considerable experience in low level flight operations. Although he carried aeronautical charts for the area in the aircraft, they did not indicate the position of the powerline.

The powerline was a single wire earth return line type, the property of an electricity authority, and had been erected some 30 years ago. In the area in which the helicopter was operating the supporting poles were approximately 1.4 km apart, where the powerline spanned a gully. The aircraft struck the powerline some 700 m from the nearest pole, whilst climbing out of the gully, some 300 ft above ground level. The powerline was not fitted with any warning markers.

On arrival at Jandakot the student pilot flew a circuit for a normal, full flap approach and landing. During the final approach the airspeed reduced below the target figure. The instructor, who was monitoring the situation, allowed it to develop beyond a point where a go-around should have been made. Neither the student nor the instructor took any corrective action, and the aircraft landed heavily on the main landing gear and the tail skid.

It was reported that the instructor allowed the situation to continue in an attempt to have the student recognise his error without intervention from the instructor. The instructor's inexperienced was probably a factor in his misjudgement as to when he should take recovery action.

The pilot said he had over corrected when the aircraft was struck by a gusting crosswind during the take-off roll. This action caused the left wing to contact the runway, slewing the aircraft sideways. The aircraft then departed the runway sliding sideways before coming to rest, upright, within the cleared area of the flight path.

Both the pilot and the passenger were able to exit the aircraft safely.

The take-off was the first solo flight for the pilot after receiving endorsement on the type.

The aircraft received significant damage to the landing gear, propeller and wings.

The pilot of the C182 had been cleared to operate over the metropolitan area at 5,000 ft, provided he remained 2 NM west of the extended centreline of Perth runways 03/21. This clearance had been issued several hours before, by a different controller to the one involved in this incident.

A C172 had also been operating over the metropolitan area at 1,500 ft and had been cleared to return to Jandakot.

The B767 was departing Perth from runway 21 and the crew intended to turn right and depart towards the north-west.

During the day, the pilot of the C182 had been following a regular, orbiting flight path which was displaced from the B767's planned departure track. After the B767 took off the C182 made two irregular orbits which took it further south than previously, and closer to the B767's path.

The approach-west controller was aware of a possible conflict between the B767 and both the C172 and C182, prior to the B767's departure. He had formulated a plan to ensure that separation was maintained. The plan required the B767 to maintain runway heading until it was clear of both aircraft. The initial clearance to the crew of the B767 was to maintain runway heading after take-off and to climb to, and maintain 6,000 ft. The altitude requirement was to keep the B767 clear of military airspace.

When the crew of the B767 gave their departure report the approach-west controller was engaged in a lengthy coordination discussion with another controller and he was not maintaining a continuous radar watch on the airborne traffic. He glanced at the radar and noted that the B767 was clear of the C172 before he directed the crew of the B767 to turn right onto 280 degrees. This turn was to allow the aircraft to use a preferred noise abatement track, one of a number that have been established in the metropolitan area. The controller had forgotten about the C182 and did not note its location when he glanced at the radar.

As the B767 established a heading of 280 degrees the C182, which was at the end of its southerly track, turned onto an easterly heading. This resulted in a reduction in vertical separation to 400 ft as the aircraft passed 2.8 NM apart. This was below the requirement to maintain at least 1,000 ft if the aircraft are less than 3 NM apart. The crew of the B767 received an electronic warning of the C182's proximity and also acquired it visually. No evasive action was necessary.

The evidence indicates that C182's long-standing clearance and its regular pattern may have caused the controller to establish a mind-set that the B767/C182 separation problem was less important than it actually was. The change in pattern was unexpected and went unnoticed. The controller's attention was distracted from the radar console by his discussion with another controller.

The combination of the unexpected and unobserved change in the C182's flight path and the distraction resulted in the controller only ensuring the B767 was clear of the C172 before he cleared the crew to turn onto a new heading.

The controller also indicated that he was mindful of the need to comply with noise abatement procedures and the priority he assigned to this may also have been a factor in his missing the impending confliction.

A Boeing 747-338 aircraft VH-EBU was inbound to Cairns on the 153 Very High Frequency (VHF) Omni-Directional Range (VOR) radial and had been assigned 3000 feet not below the DME steps. The pilot reported visual at approximately 15 NM south of Cairns and was then cleared to track for a left base for runway 15. VH-XFW an Embraer EMB-120ER was departing Cairns runway 15 for Bamaga and was given a departure instruction to turn left onto a heading of 030 degrees magnetic and to maintain 2000 ft. VH-EBU was observed by radar to descend below 3000 ft. The approach controller instructed VH-XFW to maintain 1500 ft and VH-EBU to maintain 2500 ft. The pilot of VH-EBU said it was too late and that he had the other aircraft in sight to his right. VH-EBU was then cleared for a visual approach and instructed to call the tower. VH-XFW was given climb and tracking instructions to intercept the outbound track.

Examination of the Automatic Voice Recording (AVR) tape and the radar tape showed that at 0119:20 EST the minimum horizontal separation was 1.33 NM, and the vertical separation was approximately 600 ft. The minimum separation standards are 3 NM and 1000 feet.

Interview with the crew of VH-EBU indicated that when VH-EBU was cleared to track for a left base for runway 15 (after reporting visual) it was assumed that they had been cleared for a visual approach. Accordingly, a descent to 1500 ft was initiated, which is circuit altitude. The crew of VH-EBU had not been cleared for a visual approach however, and thus had not been cleared to descend below 3000 ft.

Safety Action

The crew of VH-EBU have been counselled as to visual approach requirements, and a notice to pilots will be issued to prevent a recurrence.

During a touch and go landing, the pilot inadvertently selected the landing gear up instead of the flap while the aircraft was still on the runway. The landing gear retracted, and the aircraft slid to a stop.

During an early morning inspection of Broken Hill Aerodrome, the groundsman discovered an aircraft upside down about 300 m short of runway 23, just outside the aerodrome boundary. The owner was contacted by the local police who advised them that his aircraft had been stolen. Further police enquiries revealed that the owner had actually been the pilot, who now claimed he was suffering from amnesia, possibly caused by a head injury as the aircraft rolled over.

Later the pilot stated that he had departed his property at approximately 2000 CSuT for Broken Hill, with an arrival time of 2016 CSuT. He joined the circuit on downwind for runway 23, reduced engine power and lowered 20 degrees of flap. Turning base leg, he recalled that the engine appeared to be sluggish to throttle movement when an increase in power was required to overcome an excessive sink rate, which he thought may have been caused by the very high temperature of the day. He then retracted the flaps as he was worried that the aircraft might stall. This action probably increased the sink rate.

The aircraft contacted the ground heavily well short of the runway, continued for several metres before contacting obstacles and rolling inverted.

A friend and his family, who had visited the pilot's property that day for a barbeque, reported they had observed the pilot consume about 8 - 10 stubbies of full-strength beer during the afternoon. They departed for their property at about 2000 CSuT, and after about 15 minutes were "buzzed" by an aircraft they believed belonged to the pilot, which then continued in the direction of Broken Hill.

A thorough inspection, and test run of the engine was carried out which did not reveal any faults or malfunctions that may have caused a loss of power. An inspection of the aircraft failed to find any faults which could have contributed to the accident.

The police and the Civil Aviation Safety Authority are investigating further.