Loss of separation

On 10 December 2007 at about 2143 Eastern Daylight-saving Time a Cessna Aircraft Company 172N (C172) registered VH-WDA entered runway 17 at Essendon Airport, Vic. without an air traffic control clearance. At that time, a Piper Aircraft Corporation PA31, registered VH-BTD, was on final approach and had been cleared to land on runway 17. The pilot queried the landing clearance with the tower controller, who observed the C172's unauthorised entry onto the runway, or runway incursion, and sent the PA31 around in order to maintain separation between the two aircraft.

The pilot of the C172 was appropriately licensed, rated and current for the conduct of the private night visual flight rules (VFR) scenic flight and had notified the tower controller from the runway 17 run-up bays that he was 'ready'. In response, the controller instructed the pilot to 'taxi forward and hold short of runway 17'. That instruction was correctly read back by the pilot. Shortly after, the aircraft crossed the holding point and entered runway 17.

The C172 pilot had 311 hours total experience with 20 hours experience under the night VFR. The pilot was completing commercial pilot training and had been operating regularly at Essendon Airport over the previous 2 months. Most of those operations were reported to have been on runways 17 and 35. The pilot advised that the airport markings, signage and lighting were more than adequate for the planned flight.

The C172 pilot could not explain or rationalise why he had entered the runway when he had acknowledged the instruction to hold short of the runway. The investigation did not identify any operational factors that may have contributed to the development of the runway incursion.

On 21 September 2007, a SAAB Aircraft AB, SF-340B (SAAB) registered VH-EKX was inbound to Sydney, NSW on a scheduled passenger service from Wagga Wagga, NSW. The crew was cleared by air traffic control to track direct to short final runway 16R at Sydney Airport. The last assigned altitude issued to the SAAB crew was 2,500 ft. A Eurocopter EC120 helicopter registered VH-CKO had departed Sydney Airport on a Georges River 1 departure and, when identified on radar by air traffic control, was cleared to track direct to Kingsgrove at 1,500 ft for aerial work. Air traffic control had coordinated the positions and intended tracks of both aircraft and established a 1,000 ft vertical separation standard.

At 1058.08 Eastern Standard Time, the short-term conflict alert activated on the display consoles of the air traffic controllers. Two seconds later, the copilot of the SAAB reported that they were responding to a resolution advisory from the aircraft's traffic advisory and collision avoidance system (TCAS). Radar analysis indicated that the separation between the two aircraft reduced to 200 ft vertically and 0.5 NM horizontally. There was an infringement of the vertical separation standard of 1,000 ft.

The helicopter pilot had climbed to 2,000 ft and later reported that he had been distracted from monitoring his assigned altitude by a focus on meeting the client's photographic requirements. The pilot in command and the copilot of the SAAB both reported that they believed that they had been cleared by air traffic control to make a visual approach and had descended their aircraft to 2,000 ft.

The investigation established that there was a safety issue in that there is no requirement for a controller to confirm that descent below a previously assigned altitude has not been given in a clearance to a circuit position that does not include a visual approach clearance. Airservices Australia is examining options to address this safety issue.

At about 1717 Eastern Standard Time on 27 August 2007, a student pilot and an instructor in a Cessna Aircraft Company C172 (172), registered VH-TIX, were operating in the circuit area as the crew of a Boeing Company B737-838 (737), registered VH- VYC, was conducting a runway 01 instrument landing system (ILS) approach at Townsville Airport, Qld. The pilot of the 172 was cleared for take-off and to make a right circuit on runway 07 from a position about 700 m along the runway. The 737 was about 1.2 NM from the runway 01 threshold and descending through 400 ft at that time.

The 737 landed on runway 01 and, as it crossed the extended centreline of runway 07, the pilot observed the 172 to pass in close proximity. Radar data and pilot estimates indicated that the 172 passed about 150 m behind the 737 at an altitude of about 100 ft. There was no separation assurance.

As a result of this incident, the local procedures at Townsville were amended to require the application of the Manual of Air Traffic Services (MATS) 4.8.9 Take-off Behind Landing or Departing Aircraft on Intersecting Runways separation standard between aircraft departing runway 07 and aircraft landing or departing runway 01/19 at Townsville. In addition, the Royal Australian Air Force (RAAF) implemented an audit project to examine the compliance of Australian Defence Force (ADF) air traffic services, instructions and procedures with civil requirements.

On 8 May 2007 at about 1858 Eastern Standard Time, a Boeing Aircraft Company 767-338 (767), registered VH-OGI, was inbound to Sydney, NSW from Melbourne, Vic. on descent to 6,000 ft and a SAAB Aircraft Company 340B (SAAB), registered VH-OLL, was departing Sydney for Moruya, NSW on climb to FL140. The distance between the aircraft reduced to 1.5 NM horizontal and 400 ft vertical separation. Separation standards as specified in the Manual of Air Traffic Services (MATS) required the provision of either 3 NM horizontal or 1,000 ft vertical separation between the aircraft. There was a breakdown of separation.

The apparent distraction of the controller by his involvement in a non-operational control room discussion would probably have adversely affected his mental 'air picture' and traffic planning. That included unintentionally clearing the flight crew of the SAAB to climb through the assigned level of the inbound 767, rather than the routinely assigned intermediate altitude of 5,000 ft. The traffic manager's preoccupation with administrative duties meant that the monitoring and control of the distraction risk and operational activities in the control room was ineffective.

Action by the controllers to issue traffic information to the flight crew of the 767 and a radar vector and altitude limit to the flight crew of the SAAB quickly re-established the required separation standards.

Although no safety issue was identified as a result of this investigation, in its submission in response to the draft report, Airservices Australia (Airservices) advised of its development of an Air Traffic Control (ATC) Reform initiative. The aim of that initiative was to improve the structure and processes used by Airservices to verify ATC operational performance. At the time of writing this report, the initiative was in the design phase, with implementation planned for early 2009.

On 19 April 2007, the Darwin radar (DNR) airspace was being operated as a non-radar procedural sector due to the removal of the Australian Defence Air Traffic System (ADATS) radar data from the civil Australian Advanced Air Traffic System (TAAATS). That change in arrangements was necessary because of ongoing technical problems with the integration of the ADF data into the civil radar system.

At about 0909 Central Standard Time, the DNR controller identified that an instrument flight rules (IFR) Cessna Aircraft Company C210N, tracking from Darwin to Gove, NT at an altitude of 9,000 ft, was in conflict with an IFR Piper Aircraft Corporation PA31-350 that was tracking from Bathurst Island to Jabiru and that a breakdown of separation standards had occurred. The controller re-established the required separation.

The investigation identified that the safety management system employed by Airservices Australia did not require the conduct of an independent review of the locally conducted hazard assessment process that was utilised to manage the controller's loss of radar surveillance capabilities. This was considered to be a safety issue.

On 4 April 2007 at about 0809 Eastern Standard Time a Boeing Aircraft Company 737-8FE registered VH-VON was inbound to Sydney, NSW from Melbourne, Vic. on descent to 6,000 ft and an Airbus A330-342X, registered B-HLW was departing Sydney for Hong Kong on climb to 7,000 ft. The distance between the aircraft reduced to 1.9 NM horizontal and 600 ft vertical separation. Separation standards as specified in the Manual of Air Traffic Services (MATS) required the provision of either 3 NM horizontal or 1,000 ft vertical separation between the aircraft. There was a breakdown of separation.

The loss of separation occurred as a result of the separation that was planned by the air traffic control officer being based on an incorrect cleared flight level (CFL) that had been entered into the controller's air situation display (ASD). The investigation concluded that this data entry error occurred within 2 minutes of the air traffic controller assuming responsibility for the control position, and that the reconfiguration of the in-use console by the controller during that time increased the risk of the controller being distracted from the traffic separation task.

On 7 February 2008 at Tamworth Aerodrome, New South Wales, an air traffic controller issued a take-off clearance to the flight crew of a Bombardier Inc DHC-8-315 (DHC8) aircraft, registered VH-TQZ, for runway 30 Right. At the same time, an airport operations officer was operating a vehicle on that runway.

The controller had previously issued a clearance to the operations officer to conduct bird dispersal activities on the runway. The operations officer was monitoring his radio and heard the DHC8's take-off clearance. He advised the controller that he would vacate the runway. At the same time, the flight crew had observed the vehicle on the runway and did not commence the takeoff. The controller cancelled the take-off clearance until the runway was clear.

While these secondary safety defences effectively prevented any possibility of an accident, the issue of the take-off clearance with the vehicle on the runway constituted a breakdown of separation.

The investigation found that the controller's scan of the runway and flight strip board was not effective as a result of his pre-occupation with the management of current and pending traffic and the associated high volume of radio communications. It was also possible that the controller was experiencing some degree of fatigue at the time. The ATSB's investigation did not detect any safety issues that required consequent safety action.

On 15 November 2006, a Boeing Company 737-838 (737) aircraft was established on a visual approach to runway 01 at Brisbane, Qld. The Brisbane aerodrome controller (ADC) had issued a clearance for a vehicle driver to enter runway 01 to locate and remove debris that had been blown onto the runway strip. The ADC subsequently issued the pilot of the 737 with a landing clearance while the vehicle was still on the runway, anticipating that the vehicle would vacate prior to the 737 landing.

The ADC reported that he may have momentarily forgotten about the vehicle. An unidentified transmission, believed to have been made by the pilot of another aircraft waiting for departure, warned the ADC of the vehicle's presence. The ADC instructed the vehicle driver to vacate the runway and reissued a landing clearance to the pilot of the 737. There was a runway incursion.

Recent thunderstorm activity had resulted in unidentified debris being blown onto the active runways, requiring multiple entries for airside operations vehicles into the runway strip to locate and remove the debris.

The thunderstorm activity led to a situation where the ADC experienced a busy and complex workload for an extended period of time without a rest break. The ADC did not initially issue instructions to the vehicle driver, or adequately monitor the situation, to ensure that the vehicle vacated the runway strip so that separation was assured with the 737.

The investigation found a common misconception about the classification and reporting of runway incursion events. The ICAO runway incursion definition of an 'incorrect presence' does not preclude a presence being incorrectly authorised by an air traffic control clearance.

Discontinued Investigation

Statement of Reasons

Occurrence investigations commenced from 1 July 2003 are initially categorised as category 4 unless agreed by the ATSB Executive to be above this level at the outset. As detailed in Section 21 (2) of the TSI Act 2003, the Executive Director in empowered to discontinue an investigation at any time. Section 21 (3) of the TSI Act 2003 requires the Executive Director to publish a statement setting out the reasons for discontinuing an investigation (commenced from 1 July 2003) within 28 days of discontinuing the investigation.

On 19 August 2006, the pilot of a Tecnam Costruzioni Aeronautiche P2002 aircraft, registered VH-JFV, was tracking from Bankstown Airport to a flying training area, west of the airport. The flight was being conducted under the visual flight rules (VFR) and the pilot intended to remain in non-controlled airspace (OCTA) for the duration of the flight. The upper limit of OCTA on the intended track was 2,500 ft until 37 km west of Sydney Airport. At 1137, the aircraft was observed on air traffic control radar to be above 3,000 ft and climbing, inside controlled airspace (CTA). That placed the Tecnam in potential conflict with a Fairchild Industries Inc SA226-T Merlin aircraft, registered VH-SSM, which had departed from Bankstown for Wollongong. The Merlin was being operated on an instrument flight rules (IFR) flight.

At 1138, the Sydney Departures South controller received a short-term conflict alert on the air situation display (ASD). At the time of the alert the aircraft were separated by 900 ft vertically and 3,150 m (1.7 NM) laterally. The controller issued heading instructions to the pilot of the Merlin to avoid the Tecnam. A radar controller established radio communications with the pilot of the Tecnam and instructed the pilot to leave CTA. The pilot complied with the instruction by descending the aircraft and it left CTA at a position about 35 km west of Sydney Airport.

The pilot of the Tecnam had misidentified the aircraft's position in relation to the CTA boundary and consequently inadvertently entered CTA without a clearance. The pilot subsequently undertook additional training to ensure that he could visually identify the CTA boundaries in and around the Bankstown area