Loss of separation

When the Roulettes were cleared into the MCG from Point Ormond (PTO) at the start of the rehearsal, the airspace release that was issued by the departures (DEP) controller to the EN aerodrome controller (ADC) was "PTO to the MCG keep clear of the 26 localiser".  Prior to the start of the rehearsal an onwards clearance for the Roulettes that were to proceed to ES was issued by DEP to EN. The clearance was "track direct to MB maintain 5000 feet” Only the Roulette leader was operating a transponder.

After the Roulettes had started the rehearsal the EN ADC requested departure instructions for VH-SRJ who was departing runway 17 at EN to track via the 150 Melbourne (ML) VOR radial to Cowes (CWS) at 3000 feet. A heading of 170 or 180 was also requested to keep VH-SRJ clear of the Roulettes. DEP issued a heading of 170 unrestricted. VH-SRJ departed and remained on EN TWR frequency. The pilot of VH-SRJ was passed traffic advice on the Roulettes and reported that he had them in sight. When VH-SRJ was transferred to DEP frequency abeam Westgate Bridge (WEG), the pilot said he still had the Roulettes in sight. VH-SRJ was then vectored onto the 150 radial at 10 miles from EN by which time the aircraft was cruising at 3000 feet.

Meanwhile, the Roulettes had advised EN ADC that they had completed their Airwork and wanted an onwards clearance. EN ADC then called DEP for a clearance "MCG to Yarragon (YAR)". DEP then confirmed the previously arranged clearance of "direct MB maintain 5000 feet". EN ADC then asked the Roulettes about their details for departure and the leader advised two for LV and four for ES. EN ADC then cleared the two for LV to depart via Station Pier (SNP) at 2000 feet. The leader of the Roulettes then requested that the formation depart on a southerly heading to facilitate the breakup of the formation. This was approved by the EN ADC who then advised the four Roulettes that were bound for ES that once they were south of PTO or clear of controlled airspace to climb to 5000 feet. The EN ADC continually kept the Roulettes and other traffic holding outside EN airspace informed of each other.

At this stage DEP could see the transponder return of the Roulette leader heading for PTO at 2000 feet at 230 knots groundspeed but could not see any primary returns from the rest of the formation. He then asked EN ADC where the Roulettes were as he was expecting to see some return in the MCG area. EN ADC advised they were in the PTO area. At this time VH-SRJ was just south of and abeam PTO cruising at 3000 feet. The Roulettes that were bound for LV, including the leader using a transponder, then did a left orbit at 2000 feet and proceeded to LV.

A few seconds later a primary return was observed approximately four miles west of the 150 radial making a sweeping left arc towards MB. The formation bound for ES then called DEP and was immediately asked their present level which was reported as "left 3400 feet". A transponder code was then issued to this formation which was identified heading east towards MB leaving 4500 feet two miles east of VH-SRJ. The primary return from this formation passed within one mile ahead of VH-SRJ.

Analysis

EN TWR received a telephone call from the Roulette leader to arrange the area for the practice display. There was no consideration given to callsign requirements after the formation breakup. The display area was not specifically co-ordinated between EN TWR, DEP or the Roulette leader via intercom or air to air communication.

The DEP controller expected the Roulettes that were bound for ES to be departing from the MCG direct to MB which would have kept them clear of the 150 radial and VH-SRJ. However, the original airspace release from DEP to EN was PTO to the MCG up to 4000 feet and clear of the EN 26 localiser. Had there been a more precise description of the airspace release and onwards clearance then the EN ADC may have been more aware of the need to co-ordinate with DEP prior to clearing the Roulettes to track south.

DEP was unaware that the EN ADC had cleared the Roulettes to track south to PTO until he asked. When the Roulettes asked to track south, they were already almost over PTO with an airspeed of close to four miles a minute.

The incident occurred during a peak traffic period when both DEP and EN TWR were handling moderate to heavy traffic levels. Both the DEP controller and the EN ADC were experienced in their respective positions

Significant Factors

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

1. Co-ordination between the Roulettes, DEP, and EN TWR, both before and during the exercise was loose and lacking in specific detail.
2. Callsigns for the Roulettes after the formation breakup had not been addressed prior to the display. This resulted in the DEP controller having to access another transponder code for the ES bound aircraft at a critical period of the flight.
3. The DEP controller never issued a precise description of the airspace that was released to EN ADC.
4. EN ADC likewise did not ensure that the precise lateral and vertical limits of the airspace required by the Roulettes was co-ordinated with DEP. As a result, the Roulettes were not restricted to a specific block of airspace for their display.
5. DEP did not give a precise onwards clearance for the ES bound formation. A clearance should have been issued to ensure the formation set course from the MCG direct to MB. This was critical for separation with VH-SRJ.
6. The EN ADC did not recognise the significance of the need to co-ordinate with DEP the request by the Roulettes to track south to facilitate the formation break.

Safety Action Taken

1. The DEP and EN TWR controllers were taken off their rosters and given appropriate counselling.
2. A standardisation item is to be issued by Air Traffic Services (ATS) in Melbourne to highlight the need for precise descriptions of airspace releases along with a reminder of the need to take performance characteristics into account when formulating airspace releases.
3. Another standardisation item is to be issued to highlight the importance of being specific when defining a route clearance, particularly when it involves separation with another aircraft. This item will include a reminder that it is imperative that co-ordination is effected before any approval is given that may change the conditions of an issued clearance.
4. Discussion is taking place among ATS supervisory staff as to the best way of co-ordinating these types of activities between all involved parties to ensure that correct briefing and co-ordination is achieved.

Sequence of Events

The crew of VH-OGO, when established on final approach to runway 33, reported a TCAS RA (Resolution Advisory) against an unknown aircraft indicating half a nautical mile west at the same level, 1,000 ft AMSL. The other aircraft, VH-HSC, a helicopter, was tracking west of the Cook Highway to the south-eastern training area. A breakdown in separation had occurred.

The pilot of the helicopter had been given a clearance by SMC (Surface Movement Control) to track to the western training area via Green Hill. The ADC (Aerodrome Controller) later amended this clearance for the aircraft to remain west of the Cook and Bruce Highways. The departure of the helicopter was not monitored by the ADC due to distractions in the Control Tower. The ADC expected the helicopter pilot to track directly to the south-western section of the Bruce Highway which is due south of the aerodrome. The pilot instead tracked west of the Cook Highway which closely parallels the final approach path to runway 33.

Analysis

When the two aircraft passed each other, the helicopter which had not reached the junction of the two highways was still being operated within its clearance restriction of "west of the Cook Highway", although this was not what the ADC intended. The ADC failed to monitor the helicopter's departure thus did not ensure adequate separation of the outbound helicopter and the inbound passenger jet.

Safety Action

As a result of this incident, a caution has been inserted in the Air Traffic Services Local Instructions stating that at a departure clearance west of the Cook Highway does not provide separation with final runway 33.

VH-UJF was enroute Eildon Weir to Moorabbin at 3000 ft in controlled airspace and was approaching the reporting point Academy when the approach radar controller observed VH-AZQ approaching Academy from the Moorabbin direction at 2800 ft. VH-AZQ had penetrated controlled airspace while awaiting an airways clearance. The approach controller advised VH-UJF of the conflicting traffic and turned VH-UJF onto a heading of 270 degrees. At the same time VH-AZQ called Melbourne radar advisory service (RAS). The RAS controller advised VH-AZQ of the conflicting traffic and verified the level of VH-AZQ as 2500 ft. Both aircraft came within 2 NM of each other in visual meteorological conditions.

An unidentified aircraft, later identified as VH-JEB, was observed inside the Melbourne control zone in the Sunbury area on a south-south-easterly heading. The mode C readout showed the aircraft was at 1900 feet. At the same time, VH-CZU was becoming airborne from runway 27 on an "Avoca one" departure. VH-CZU was instructed to maintain runway heading and asked to look for the other aircraft. The crew of VH-CZU sighted VH-JEB and passed two miles in front of it and 200 feet higher.

The pilot of VH-JEB reported that he had become distracted after initiating a diversion back to Essendon due to concern about fuel reserves. He was conducting a solo navigation training exercise.

Two heavy, international passenger aircraft were approaching Australia from the North West. Whilst they were in airspace under the control of the Perth Sector 2 Air Traffic Controller, communication with the aircraft was being provided by a Flight Service Officer manning the Perth Flight Information Service International 1 position. The lead aircraft requested a climb and was cleared to Flight Level 310. The following aircraft also requested a climb and the Air Traffic Controller passed a clearance to the International Flight Service Officer indicating that the aircraft was cleared to Flight Level 290. Shortly after the following aircraft commenced climbing, the lead aircraft advised that the TCAS system had indicated that there was an aircraft behind and below presenting a confliction.

The Flight Service Officer had incorrectly passed a clearance to the following aircraft for a climb to Flight Level 310 instead of Flight Level 290, and the following aircraft was detected and reported by the lead aircraft. The following aircraft descended to Flight Level 290.

The Flight Service Officer had written the correct clearance on the flight strips but had passed the incorrect level to the aircraft. The officer could not explain this, however the investigation identified some preconditions which may have contributed to the occurrence

a. The incident occurred during the last five minutes of the Flight Service Officer's ten hour shift which was due to conclude at 2300 hours. The Flight Service Officer had spent the entire shift, with appropriate breaks, working on the same operating position. Normal procedure is to attempt to rotate staff through different positions.

b. The workload, which had been light earlier in the shift, peaked just prior to the incident and was heavy and complex at the time of the incident.

c. The Shift Supervisor's workload monitoring process did not detect that the Flight Service Officer's workload had become complex and heavy and that he may have been in need of assistance.

d. The Air Traffic Controller working Sector 2 did not note the incorrect clearance, given by the Flight Service Officer, although the information was available through a Flight Service monitoring facility (part of the safety net) available to and used extensively by him prior to the incident. It is probable that the Air Traffic Controller's workload had also reached a point where he was unable to provide a monitoring service.

e. A number of environmental and organisational issues were reported as having developed from the uncertainty of the continued operation of the Flight Service organisation following the Civil Aviation Authority's airspace review. Areas such as inadequate working conditions and low staff morale were reported as major issues.

Safety Action

The Civil Aviation Authority are planning to resolve rostering and supervision issues by implementing the "team" concept for staffing within Flight Service centres. They are also employing contract staff in an attempt to reduce the load on their permanent staff.

VH-TQR departed Sydney on Runway 25, Radar 3 departure, and was cleared to climb to an initial altitude of 5,000 ft, on a radar heading of 240 degrees. The altitude restriction was to provide vertical separation with inbound traffic. The aircraft was under the control of the Departures South Controller.

VH-OGB was inbound to Sydney from the southwest, being radar vectored by the Approach South Controller for a left circuit to runway 34L, and had been assigned a heading of 050 degrees, on descent to 5,000 ft. This placed VH-OGB and VH-TQR on crossing tracks with a convergence angle of about 170 degrees. The crew of VH-OGB received a Traffic Alerting and Collision Avoidance System (TCAS) Traffic Advisory warning which indicated an aircraft climbing towards VH-OGB, 1,800 ft below. They expected the TCAS traffic would level off 1,000 feet below them. As VH-OGB was in visual meteorological conditions, a lookout was commenced for the traffic. VH-TQR was not fitted with TCAS. The conflicting traffic was then observed on TCAS, climbing some 500 feet below VH-OGB.

The Approach South Controller instructed VH-OGB to turn right heading 090 degrees to position for landing on runway 34L. The other traffic passed off the TCAS screen behind VH-OGB, without the crew sighting the aircraft. Minimum vertical separation indicated by TCAS was 300 ft. Neither the Departures South nor Approach South controller recognised the traffic conflict, and no traffic information was passed to either aircraft.

Recorded radar data confirmed the conflicting traffic was VH-TQR which passed within 1 NM of VH-OGB, with a minimum vertical separation of 500 ft. The minimum separation standard required for air traffic control purposes was 1,000 ft vertical or 3 NM lateral.

New air traffic handling procedures for departing and arriving aircraft were introduced at Sydney one week prior to the incident. Among the changes was an alteration to the vertical division for airspace in the vicinity of Sydney Airport between the Departures and Approach Controllers. The controller who occupied the Approach South position had minimal familiarity with the new procedures. He inadvertently reverted to old procedures and incorrectly assigned VH-OGB an altitude of 5,000 ft instead of 6,000 ft. Neither the Departures South nor the Approach South controller had been monitoring the vertical progress of their respective aircraft, at the point at which the flight paths crossed.

The B737 was inbound to Coolangatta, heading 340 and on descent to 7,000 ft. This heading would take the aircraft across the extended centreline of runway 14. The SA226 had been cleared to climb to 5,000 ft on runway heading after take-off from runway 14. The B737 was subsequently cleared to 2,000 ft to join right downwind for runway 14. Shortly after the SA226 levelled at 5,000 ft, the B737 passed in the opposite direction approximately 1.5 NM east and 500 ft below the SA226. The separation standard required was 3 NM horizontal/1000 ft vertical separation.

The responsible controller was under a moderate to high workload in the period leading up to the incident. In addition to other departing and arriving traffic, there was traffic to the north of Coolangatta being handed off to Brisbane and a parachuting aircraft awaiting run-in for a drop near the aerodrome.

It appears that the high workload and other traffic considerations distracted the controller to the extent that he forgot about the SA226, at least temporarily. The appropriate technique would have been to provide separation assurance by way of the departure clearance. The controller indicated that he may have been suffering a degree of fatigue at the time of the incident, and this may have affected his performance.

Following take-off from runway 01 at Townsville, the military aircraft, Stallion 080, was instructed to turn right and climb to flight level (FL) 120. VH-TNX departed from the same runway and was instructed to turn left to intercept the track to Cairns. When Stallion 080 reported at FL120 the Townsville controller requested the level of VH-TNX. The pilot of that aircraft replied passing FL110 and was instructed to report leaving FL130, and to climb at the best rate of climb. The controller then asked Stallion 080 to report sighting VH-TNX, after a short delay the pilot reported that the aircraft was in sight and that he would maintain separation visually.

Subsequently, Stallion 080 passed VH-TNX on the left side at about the same level, approximately 200 metres away.

The method by which the Townsville controller attempted to maintain separation between the two aircraft was not correct for the situation. The Manual of Air Traffic Services does not allow for one aircraft to visually separate itself from another aircraft at the level the aircraft were operating. However, there were a number of other techniques, that could have been employed by the controller, to maintain the required separation between the two aircraft.

The pilot of Stallion 080 reported that he was unable to manoeuvre his aircraft to pass further from VH-TNX as this would have required abrupt action and may have resulted in injury to standing passengers in his aircraft.

The crew on VH-EWA were conducting circuit training at Melbourne Airport. On the base leg turn for runway 34 the crew reported sighting another aircraft which had passed above them.

The other aircraft was VH-TXN, which had entered the Melbourne control zone without a clearance. The pilot of VH-TXN was proceeding from Tyabb to Shepparton and the pilot was intending to track around the southern and western boundaries of the zone. No contact was made with the aircraft until the pilot later called on the Radar Advisory Service (RAS) frequency at Rockbank.

Subsequently the aircraft again entered the zone without a clearance near Sunbury. The aircraft was not on the RAS frequency at the time. Subsequently RAS made radio contact, and the pilot was given radar headings to clear the zone near Beveridge.

Later checking of the plan for VH-TXN showed the pilot had made calculation errors in estimating the appropriate headings to fly and also errors in the time intervals. Enroute navigation errors also occurred.

Significant Factors

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

1. Poor flight planning by the pilot of VH-TXN.

2. Poor inflight navigation procedures by the pilot of VH-TXN.

Two aircraft were flying in opposite directions on the track between Mackay and Clermont. The inbound aircraft to Mackay was being held at 5,000 ft until the outbound aircraft had passed. The outbound aircraft was maintaining 4,000 ft. The controller estimated that the two aircraft would pass at about 21 NM from Mackay.

The controller was using Distance Measuring Equipment (DME) reports from both aircraft to obtain the required separation before allowing further climb or descent. When the inbound aircraft reported at 20 DME, and the outbound aircraft reported at 25 DME, he allowed the inbound aircraft to descend. Just after passing 4,500 ft the pilot of the descending aircraft sighted the outbound aircraft straight ahead and slightly below. He took avoiding action and reported the event to ATC.

It was subsequently determined that the pilot of the outbound aircraft had not been trained in the use of DME, and that the equipment in the aircraft was unreliable. When asked for DME distances he had provided dead reckoning distances obtained by map reading, which were incorrect.