The crew of the Beech 1900D (B1900) aircraft had been cleared by the aerodrome controller (ADC) 1 to descend to 4,000 ft and were instructed to join the circuit via a left base leg for runway 12L (northern) circuit at Tamworth. The ADC 1 also instructed the crew to report approaching 4,000 ft. The crew acknowledged the clearance but later advised that they were unable to report approaching 4,000 ft due to frequency congestion. The ADC 1 had assigned 4,000 ft so that a procedural separation standard of 1,000 ft could be maintained with other aircraft until he could see the B1900 and apply visual separation.

The crew of the B1900 subsequently requested confirmation of their assigned level and reported their position when at 2NM north of the aerodrome. The controller then sighted the aircraft and cleared the crew to make a visual approach. The controller also asked the crew if they would need to extend through the centreline of runway 12L. The crew acknowledged the visual approach but did not advise the controller that they would need to extend through the centreline. The visual approach clearance authorised the crew to descend below 4,000 ft.

The crew of the B1900 could not comply with the instruction to join the circuit via a left base for runway 12L because the aircraft was too high and too fast. The co-pilot was the non-flying pilot and was undergoing command upgrade training. He had acknowledged the clearance for the visual approach and had previously acknowledged the instruction to join the northern circuit via a left base leg for runway 12L. At the time that the visual approach clearance was issued, the pilot-in-command was aware that they could not comply with the circuit entry instruction. He believed that the controller would have been aware that they were unable to enter the circuit on a left base leg, given their proximity to the circuit at that time and the height and speed of the aircraft. He also believed that the controller would have taken those circumstances, and the disposition of traffic in the southern circuit, into account when issuing the visual approach instruction.

The B1900 continued to descend and entered the runway 12R (southern) circuit airspace which was under the control of the ADC 2. The ADC 1 notified the ADC 2 that the B1900 had entered the southern circuit. The ADC 2 advised the ADC 1 that there was a Pacific Aerospace Corporation Airtrainer CT4B (CT4) on a right base leg for runway 12R. The ADC 2 provided traffic information about the B1900 to the crew of the CT4. There were four other CT4 aircraft inbound to the circuit at that time but the ADC 2 had not sighted them. The ADC 1 was unable to apply the required separation standard, either 1,000 ft vertically, or a minimum horizontal distance determined using the appropriate `Lateral Separation' standard from the Manual of Air Traffic Services (MATS), between the B1900 and the traffic inbound to the southern circuit. There was an infringement of separation standards.

The ADC 1 reported that he had sighted the CT4 on right base. He then instructed the crew of the B1900 to make a right turn and track via a right base leg for runway 12L. He believed that the B1900 was visually separated from that CT4 and that he could maintain visual separation between the B1900 and that CT4 with that instruction. He did not think that there had been an infringement of separation standards between the B1900 and the aircraft inbound to the southern circuit because all parties had enough time to ensure that visual separation was not infringed.

A Boeing 747-200 (B747) was being radar vectored from the west for sequencing to runway 21 at Perth. A de Havilland Canada DHC-8-102 (Dash 8) was being radar vectored from the east for sequencing to land on runway 21 behind the B747. When the crew of the Dash 8 reported that they had sighted the B747, the air traffic controller assigned them the responsibility for separation from the B747. The rate of closure between the two aircraft was high and the crew of the Dash 8 received a traffic advisory from their traffic alerting and collision avoidance system. Although the Dash 8 crew was being issued with radar vectoring instructions by air traffic control, they were obliged to turn their aircraft to the right to avoid the B747.

Radar data and air traffic control automatic voice recordings were reviewed to establish the sequence of events. The investigation found that the approach controller had assigned the responsibility for separation to the pilot of the arriving Dash 8 while the aircraft was being radar controlled. The radar separation standard required 3NM horizontal separation while there was less than 1,000ft of vertical separation. During the occurrence, radar separation reduced to 1.82NM when there was 100ft vertical separation. A radar or vertical separation standard was not required when some other form of separation was being applied. In this situation the controller was relying on visual separation.

Visual separation of air traffic may have been a valid method to use in circumstances where less than the required radar separation is achievable. However, the criteria for the application of the standard were clearly detailed in the Manual of Air Traffic Services (MATS) Part 4 Section 5. In particular, MATS 4.5.1.11 stated:`In circumstances where an aircraft has been instructed to maintain separation from, but not follow, an IFR aircraft, traffic information shall be issued to the IFR aircraft, including advice that responsibility for separation has been assigned to the other aircraft'. The arriving B747 was an IFR aircraft but was not provided with the required traffic information.

The pilot of the Cessna 402 (Cessna) had been cleared by the aerodrome controller (ADC) to land on runway 16R at Sydney Kingsford Smith airport. The ADC monitored the aircraft's approach and after landing it was established that the pilot had landed on taxiway Alpha, which was parallel to, and to the right, of runway 16R. There was no other aircraft on taxiway Alpha at the time. The weather was visual meteorological conditions (VMC).

The pilot of the Cessna had approximately 3,000 hours flying experience and had planned to operate an instrument flight rules (IFR) charter flight from Broken Hill to Bankstown via Dubbo. En route the pilot amended the destination to Sydney in an attempt to assist the passengers to connect with their next flight. The pilot had never operated into Sydney but had recently operated into Adelaide and felt that he could self-brief satisfactorily using the Aeronautical Information Publication (AIP) documents. He was familiar with Bankstown but predominantly operated in country areas where, generally, runways had limited or no markings.

Runway 16L was 2483 m long and runway 16R was 3962 m long. Each runway had a parallel taxiway located to the right. Runway 16L was 1037 m to the left of runway 16R and taxiway Alpha was 183 m to the right of runway 16R. Runway 16R threshold was 2,862 m north of the runway 16L threshold. Runway 16R threshold was 497 m north of the intersection of taxiways Alpha and Foxtrot. The colour of the surface of taxiway Alpha changed between taxiways Foxtrot and Golf due to a bitumen/concrete join.

The flight departed Dubbo at 1445 Eastern Standard Time. The pilot tracked via Bindook and was issued with an Odale 2 standard arrival clearance to the aerodrome. He was using the AIP En Route Supplement to assist in orientating himself with the aerodrome layout and made a visual approach to final for runway 16R. He reported that when the aircraft was on the [right] base position he had an uninterrupted view of the area and could see what appeared to be the parallel runways. At the time, the pilot did not appreciate the distance between the runways and the extent of the offset of the runway thresholds. He aligned the aircraft with what he thought was runway 16R, but in fact was taxiway Alpha, with the intention of landing. The ADC issued a landing clearance and as the aircraft passed 1,500 ft on descent the pilot saw a Boeing 747 enter the taxiway he had intended to use. The pilot elected to go around and advised the ADC that he was initiating a go around. The ADC coordinated a clearance with the departure controller and instructed the pilot to turn onto a heading of 170 degrees, to climb to 3,000 ft and to contact the departure controller. The pilot did not query the ADC with respect to the aircraft entering his intended runway as he immediately complied with the instructions and changed to the departure radio frequency.

The ADC saw that the Cessna was high on final and believed that the pilot conducted the go around because the aircraft was too high and did not query the pilot about the approach. The prime means for the ADC to establish aircraft positions was by monitoring aircraft visually. The ADC had an air situation display (ASD), plus access to a surface movement radar (SMR) display to assist in confirming positions of arriving and departing aircraft, and aircraft on the aerodrome. The resolution of both displays was dependent on the selected scale and was also limited, to some extent, by the lateral proximity of runway 16R and taxiway Alpha.

The aircraft was re-sequenced for another visual approach to runway 16R. During the second approach the pilot again aligned the aircraft with what he believed to be runway 16R and subsequently landed on taxiway Alpha.

Runway 16R and taxiway Alpha were marked in accordance with Civil Aviation Safety Authority Rules and Practices for Aerodromes.

Taxiway Alpha had:

1. centreline markings, and
2. sideline markings.

Runway 16 had:

1. threshold markings,
2. designation or number (16R) markings,
3. centreline and sideline markings,
4. fixed distance markings, and
5. touchdown zone markings.

Runway 16R was served by an instrument landing system (ILS) navigation aid which provided centerline and glidepath guidance to pilots of aircraft that were fitted with ILS avionics. It also had a T-VASIS that provided a visual approach slope indication. The Cessna was not fitted with an ILS and the pilot was not qualified to conduct an ILS approach. The pilot was instructed by the director controller to report the runway in sight. The pilot reported he had the "aerodrome in sight". The controller did not subsequently query the pilot to confirm that he had the runway in sight. The requirement to report the runway in sight was a function of independent visual approach procedures and was not a runway allocation procedure.

During the second approach, the distance between the Cessna and an aircraft ahead in the approach sequence was reducing and was likely to infringe the required wake turbulence separation standard of 6 NM. The director asked the pilot if he was happy to continue the approach with less than the standard separation. The pilot reported to the director that he was happy to continue. Manual of Air Traffic Services (MATS) procedures required controllers to "ensure that the appropriate wake turbulence minima are applied at the landing threshold" for aircraft on final approach to the same runway. The intention was for only pilots to initiate requests for wake turbulence waivers. Controllers were not to initiate such requests.

A Cessna T207A aircraft, with seven persons on board, was departing Jabiru for a local scenic flight. The operator reported that the control rod end for the right aileron disconnected and the aileron deflected upwards shortly after the aircraft had rotated for take-off. The take-off was continued as there was insufficient runway remaining to stop the aircraft. A significant amount of left aileron input was then required to counteract the tendency for the aircraft to roll right. The pilot was able to conduct a normal left circuit and landed the aircraft safely at the departure runway. There were no injuries to passengers or crew, and no damage to the aircraft.

The investigation found that the swivel joint for the rod end, which attached to the outboard end of the right aileron control rod, had fractured and separated at the base of the threaded section. The rod-end fitting consisted of a rounded but flat-sided cast-alloy housing with a threaded tail section, which was attached to the interconnecting drive rod from the wing. The housing contained a spherical bearing with a bolt through the centre (at ninety degrees to the threaded tail) which connected the drive rod to the aileron control surface.

Metallurgical examination confirmed that the rod-end bearing had seized in the housing due to surface corrosion on the sliding surfaces. That action had exposed the threaded shank section of the fitting to elevated bending loads, rather than the push-pull loads for which it was designed. Cracking then initiated and propagated, through about 50% of the rod-end cross section, under normal operating conditions over an extended period before finally separating.

Examination of the maintenance documentation for the aircraft showed that the failed rod end was fitted to the aircraft as a new item on 14 Oct 1999. The rod end failed in service on 13 June 2001. At that time, it had completed a total of 754.3 hours time-in-service. The rod ends did not have a time-in-service life and were listed by the manufacturer as an "on condition" item.

The company reported that it had a policy of changing all control rod swivel-end fittings when their aircraft underwent repainting; approximately every 4-5 years. The investigation was unable to determine why the rod end was not changed at the last repaint.

The BAe 146 aircraft had departed Brisbane, Qld on a flight to Mackay, Qld with a carried-forward defect that required the number 1 air conditioning pack to be used as the sole source of air for the cabin and flight deck. That situation was permissible under the terms of the aircraft's Minimum Equipment List (MEL), which allowed operation of the aircraft in non-standard configurations. The number 2 pack was not to be used because an intermittent oil leakage in the number 4 engine was a potential source of air contamination to air conditioning pack two.

During normal operation, bleed air from engines one and two was fed to pack one which in turn normally supplied conditioned air to the flight deck and cabin. Bleed air from engines three and four was fed to pack two, which normally supplied air to the cabin only. Additionally, bleed air from the auxiliary power unit (APU) was used by either pack during the take-off and landing phases or when air conditioning was required on the ground.

The flight to Mackay was uneventful. During the approach to land, the APU was selected as the bleed air source for pack one and the configuration remained that way until the aircraft was parked, the engines were shut down and the passengers disembarked.

From the time the aircraft turned off the runway, the crew was aware of a strong oil smell coming from the air-conditioning system. The fumes were detected in the cabin as well as the flight deck. Because it was a short taxi distance and a busy period on the flight deck, the crew did not have time to investigate the origin of the contaminated air. Although the smell was generally described as oil-like, the moderate south-east surface wind may have added to the air contamination by directing engine exhaust fumes into the APU air intake.

The pilot in command vacated the aircraft to get some fresh air and a short time later he suffered headache, itchy eyes, nausea and a bad taste. Company engineers at the Brisbane and Adelaide bases were consulted by telephone and a decision was made to proceed with the scheduled return flight to Brisbane using engine air one and two as the sole source of air to pack one. As the pilot in command was still suffering from the symptoms described above, he checked with the first officer and confirmed that he was unaffected by the fumes incident and requested the first officer to be the handling pilot on the next sector.

The passengers were embarked, the doors were closed and the engine start procedure was commenced. During the turnaround, the air conditioning had been turned off and remained off during the engine start. However, the cabin fan, which distributed air to the cabin through individual louvres above each passenger seat, was on. After starting three of the four engines the pilot in command felt increasingly unwell and the cabin staff also became aware that they were being affected by the fumes. The pilot in command then cancelled the flight and later expressed concern that he had considered attempting a flight while still feeling the effects of the air contamination. He stated that he may have been influenced by his desire to consult his Designated Aviation Medical Examiner in Brisbane as soon as possible. He also noticed that he had made simple errors during the flightdeck preparation and put those errors down to the effect of the fumes on his thought processes. Previous incidents have indicated that operating crews were not aware of their impairment and the subsequent effect on their decision making ability. The seriousness of that aspect was reflected in the decision by the Civil Aviation Safety Authority (CASA) to adopt a United Kingdom Air Accidents Investigation Branch (AAIB) recommendation requiring flight crew to use oxygen masks selected to 100 percent when there is a suspicion of flight deck or cabin air contamination.

A Licensed Aircraft Maintenance Engineer (LAME) was dispatched to Mackay to investigate the source of the fumes. The engineer carried out an inspection in accordance with a CASA airworthiness directive AD/BAe146/086, issued 30 March 2001, and British Aerospace Systems Information Service Bulletin (ISB) 21-150. The ISB required certain actions to be performed whenever a cabin air quality problem was identified, which was suspected of being associated with oil contamination of the air supply from the air conditioning packs. The engineer's inspection of the air conditioning system, engines and APU revealed no signs of oil contamination or oil leaks. The aircraft was ferried to Brisbane where further investigation, including an air test, confirmed that the number 4 engine was producing fumes during the climb and the descent and the APU was continuously producing fumes. Subsequently the number 4 engine and the APU were replaced.

The two cabin staff received medical advice and resumed their flying duties. Medical tests were carried out on the pilot in command but no abnormalities were detected and he resumed flying duties one week after the incident. The co-pilot was unaffected by the fumes.

Particular attention has been paid to this type of problem in Australia since July 1997 due to apparently similar incidents and crew reaction. A number of organisations, including the ATSB, have been conducting investigations into the subject of air quality in BAe146 aircraft. Evidence from previous incidents of air system contamination on this type of aircraft has indicated that the fumes are associated with engine or APU oil contamination of the air conditioning system. As a result, operators have incorporated various modifications to the cabin air system, APU and engines. They have also introduced improved maintenance practises to further address the issue. However, that action has not completely solved the problem. The air supplied to the air conditioning packs is protected from contamination by oil seals in the engines and APU. A technical defect arising in one of these seals can result in oil entering the cabin air conditioning system with the first signal of the defect being an awareness of fumes by the members of the crew. The difficulty of identifying the origin of the contamination is exacerbated by the often intermittent nature of the fume events.