Loss of separation

Mariner 398 was tracking from Richmond to Nowra, via Camden and Wollongong. The crew had planned at 8000 ft but due to other traffic the aircraft was restricted to 7000 ft initially. The track took the aircraft close to D595 which is used for parachuting at Wilton. At 1215 the aircraft was approaching Camden.

VH-WRT departed from Wilton at 1210 for parachute operations and requested clearance to climb to flight level 130. The pilot was told by the sector 12 air traffic controller to climb to 7000 ft and remain within 3 miles of Wilton.

The sector 12 air traffic controller co-ordinated details on VH-WRT, including the 7000 ft altitude limit, with Sydney departures south. In response the controller was given identification on Mariner 398 and told that Mariner 398 was at 7000 and would call sector 12, eventually, at 8000 ft.

The sector 12 controller told the pilot of VH-WRT, at 1218, to maintain present altitude. The pilot acknowledged and said he was at 6300 ft. Subsequently the sector 12 controller passed traffic information on Mariner 398 to VH-WRT. The two aircraft passed with 700 ft vertical separation and one mile horizontal separation. The minimum separation required was 1000 ft vertical or 5 miles horizontal.

Significant Factor

The following factor was considered relevant to the development of the incident:

1. A lapse on the part of the sector 12 air traffic controller meant that the required separation was not applied.

At time 1831, 3 minutes after departure, a clearance was issued to the pilot of   VH-AJJ to track via Savoy and planned route with a climb to FL310.

No separation standard, i.e. 10 minutes or 1000 feet in altitude, was established between VH-AJJ and VH-JJQ.

At time 1839, VH-JJQ reported passing T84C at 1839, FL270, estimating Curtin at 1934. This transmission was made on the Perth Sector 2 (134.5) frequency.

At time 1843.5, the pilot of VH-AJJ reported maintaining FL310 and requested a higher level. VH-AJJ was now vertically separated from VH-JJQ.

The Controller was preoccupied with a separation problem in the vicinity of Karratha and did not fully assess the situation between VH-JJQ and VH-AJJ. It was also moderately busy at the time and a number of transmissions took place around the time of the incident. As a consequence of the workload, the Controller took the advice of the Sector 2 Controller who advised her to assign VH-AJJ FL310 due to SIA7220.

The Sector 2 Controller also entered a time when VH-AJJ would leave lateral conflict with SIA7220 on the flight progress strip for the Sector 1 Controller. This led the Sector 1 Controller to think that the Sector 2 Controller had looked at the entire scenario and offered a solution that would separate all the conflicting traffic.

The Sector 1 controller then issued a clearance to the pilot of VH-AJJ to climb through the level of VH-JJQ without fully assessing the traffic situation.

VH-NMA was en route from Perth to Meekatharra at 27,000 feet (FL270) and had passed position Mount Magnet at time 0810 and was estimating Meekatharra at 0831.

VH-FMQ departed Readys for Perth at time 0801 and was estimating Mount Magnet at 0819 and had planned at FL260.

In addition, VH-LBX was en route between Peakhill Mine and Perth. This aircraft had planned via Meekatharra (estimate 0825) and Mount Magnet (estimate 0848). VH-LBX was issued with a requirement to Reach FL240 by Meekatharra to facilitate separation with the other traffic.

At time 0813.5 a clearance was issued to the pilot of VH-FMQ to transit via planned route, to climb to FL220, and to expect higher levels at Mount Magnet.

At time 0816 an instruction was passed to the pilot of VH-NMA to leave control area on descent with a requirement to reach FL230 by time 0820. This was done to ensure separation with VH-LBX.

The pilot of VH-NMA queried the requirement and was told it was due to traffic. VH-NMA then commenced descent.

At time 0819.5, the pilot of VH-NMA reported leaving FL230 and requested the traffic.

The Perth Sector 4 Controller advised the pilot of VH-NMA that he could expect a short delay at FL230. The pilot queried this, stating he had just left FL220. The Sector 4 Controller then told the pilot of VH-NMA to report leaving FL210.

At time 0821, the pilot of VH-FMQ reported passing over Mount Magnet at time 0819, maintaining FL220.

The aircraft were now established on opposite sides of a Navaid and adequately separated.

The Sector 4 Controller had predetermined how to separate the aircraft involved, but gave the pilot of VH-NMA an

instruction to leave control area on descent, instead of limiting decent to FL230 to remain separated from VH-FMQ.

Prior to issuing the descent clearance, the Controller did not advise the pilot of VH-NMA of the plan to enable him to descend into Meekatharra without experiencing extensive delays. Had this been done it is likely the pilot of VH-NMA would have realised the error when he was given descent below FL230.

VH-FMQ passed over Mount Magnet at time 0819 which was the time that NMA reported leaving FL230, so although separation existed, the Controller was unaware of the fact.

The Controller was experienced and, at the time was also performing Team Leader duties.

A review of the flight strips indicated that no times of passing between the aircraft were recorded on the flight progress strips and other details missing indicated that the Controller was not performing at the required technical level at the time.

The traffic levels in Sector 4 when it is busy, particularly in the vicinity of Mount Magnet, may warrant a separate flight progress board bay designator for Mount Magnet. This would make it much easier to visualise conflictions than the current method where the Mount Magnet position is located adjacent to the Mount Singleton designator.

Safety Action

The Civil Aviation Authority are reviewing the possible use of a Mount Magnet designator on the flight progress board.

The pilot of VH-CYT landed the aircraft on runway 35. On the landing roll he asked the tower for clearance to turn left into runway 12/30. Because another aircraft, VH-CSZ, was about to land on runway 12 the air traffic controller told the pilot of VH-CYT "negative, continue through the intersection without delay".

The pilot of VH-CYT misunderstood the instruction and turned left into runway 12/30. VH-CSZ had already been cleared for a touch-and-go landing on runway 12 and was already on the ground when VH-CYT turned left. The controller issued instructions to both aircraft to stop. They both came to rest on the runway, with about 350 metres space between them.

Significant Factor

The following factor was considered relevant to the development of the incident:

1. The pilot of VH-CYT misunderstood the instruction given by the tower controller.

The crew of VH-YSB had flight planned for an examination flight test to be conducted in accordance with Japanese Civil Air Board procedures which required a practice instrument landing system (ILS) approach to a minimum of 200 ft above aerodrome elevation.  They had briefed for a left turn from the runway 35 minima at Canberra.

Due to equipment limitations at Canberra, air traffic control (ATC) had instituted a system of slot times for any pilot requesting a practice ILS.  The pilot of VH-YSB had obtained approval for such a practice ILS and had also advised ATC that he would be carrying out a Category One ILS.  As ATC had no special instructions relating to the words 'Category One' in the notification of a Category One ILS at Canberra, no further action was taken by them in relation to that part of the flight plan advice.  Their expectation was for VH-YSB to carry out a standard ILS to the normal published decision height of 330 ft above the aerodrome elevation. As far as ATC were concerned, this was the only minimum for this approach and the instructions issued to aircraft were based on the use of this minimum.

The Canberra runway 35 ILS is not approved for Category One operations. The Category One ILS is designed for landings in extremely poor weather conditions and requires additional ground facilities which are not yet provided in Australia.

The crew of VH-YSB were cleared for final by Canberra Approach and were instructed to contact the tower for further instructions, which they did.

VH-ILL had completed a solo training exercise to the north of Canberra and was being processed by the aerodrome controller (ADC) for a right circuit to runway 30.

The ADC was under training and being supervised by an appropriately rated training officer.  The pilot of VH-YSB requested a left break and left circuit from the ILS.  The ADC decided that because of the traffic situation, such a procedure was not appropriate and issued instructions for VH-YSB to make a right break at the minima and then conduct a left circuit for a landing on runway 30.  There was some confusion between ATC and the crew of VH-YSB at this point but a correct readback of the instructions was obtained.

The ADC had been assessing the situation in relation to a landing sequence between VH-YSB and VH-ILL.  He decided that VH-ILL would be number one and issued instructions to achieve this sequence.  Consequently, he re-issued the break instruction to VH-YSB but in so doing included the words 'at the minima or when ready'.  This was misinterpreted by the pilot as an additional approval to continue to a minimum of 200 ft as required by the company's examination procedures.

The ADC decided to add a further requirement for VH-YSB to remain south of the field at all times in the break as this would add an additional safety buffer between the two aircraft.  Although this instruction was issued, no readback was obtained from the pilot and the crew do not believe they received such an instruction.  Examination of the automatic voice recording indicates that the pilot and ADC were probably transmitting at the same time and did not receive each other's message.

VH-ILL had continued an approach to runway 30 in accordance with ATC instructions.  As VH-ILL was on final approach VH-YSB had commenced its go-around from a 200 ft and, realising that he would be unable to make a left circuit for runway 30, the pilot levelled the aircraft wings to overfly runway 30.  His intention was to make a right circuit contrary to the instructions from ATC.  The pilot believed that this was the safest course of action he could perform from his position and that this action would enable him to comply, as near as possible, with the last ATC instruction.

The ADC training officer realised that VH-YSB was not going to remain clear of the flight path of VH-ILL and immediately gave traffic information on VH-ILL to the crew of VH-YSB.  Because VH-ILL was crossing the threshold with a landing clearance and VH-YSB was climbing and seen to be above VH-ILL, the training officer decided that no further action was necessary to prevent a collision and re-cleared VH-YSB for a right base to runway 30.

The aircraft passed within 150-300 ft of each other.

The training manual in use by the flying school states that such flight tests will descend to 200 ft before commencing a break.  However, ATC instructions only refer to the published minima, in this case 330 ft.

The go-around instruction given by ATC was designed to be commenced by 330 ft and would provide sufficient room for a safe left circuit to runway 30. Both ATC and the crew of VH-YSB agree that the position of the aircraft at the commencement of the break did not permit a safe execution of this manoeuvre.

The phrase used by the ADC, 'at the minima or when ready', was designed to allow a pilot to commence the break earlier than the minima if an easier transition to downwind leg was required.  However, in this occurrence it only served to reinforce the pilot's belief that he could continue to 200 ft.

Findings

1. The flying training school's advice to ATC of a Category One ILS approach had no meaning to the controllers.
2. There were no ATC instructions referring to runway 35 ILS approach minima below 330 ft.
3. The Canberra runway 35 ILS approach is not approved for Category One operations.
4. The crew of VH-YSB continued below the published minima for the approach being used.
5. The company training manuals used by the crew of VH-YSB specify a Decision Height of 200 ft for this particular examination.
6. The company training manuals used by the crew of VH-YSB had been accepted by the Civil Aviation Authority.
7. The go-around instructions issued by ATC were not able to be safely complied with from 200 ft.
8. The phraseologies used by ATC in issuing overshoot instructions were confusing to the crew of VH-YSB.
9. The ATC requirement for VH-YSB to remain south of the airfield in the right break was not received by the crew of VH-YSB.
10. The ADC was unable to provide adequate visual separation.
11. A breakdown in separation standards occurred.

Significant factor

The implications of the notification of a CAT 1 ILS by the flying training school, had not been disseminated to ATC.

Safety Action

As a result of the investigation:

1. ATS management at Canberra reviewed and amended the phraseologies in use at Canberra for overshoot instructions in similar circumstances.
2. The flying training school has reviewed and amended its notification requirements for ILS training flights.

The pilot of VH-LLY was cleared for descent in Darwin controlled airspace from FL330 to 5,000 ft, on a heading of 085, for radar vectoring to the ILS. VH-JPW had departed Darwin, and the pilot was cleared for climb to FL330, on a heading of 163.

During descent, as VH-LLY was passing through 8,000 ft with a 3,000 ft per minute rate of descent, the pilot heard Darwin Approach advise the pilot of VH-JPW of unidentified traffic in his 2 o'clock position, and to maintain 6,000 ft until clear. He looked out and sighted another aircraft rapidly approaching and realised that he must be the unidentified traffic. He resumed control from the co-pilot, made an immediate left turn and passed behind the other aircraft, with an estimated separation distance of 200m.

He then contacted the pilot of VH-JPW and Darwin Approach to advise them of the occurrence. The pilot of VH-JPW believed that if he had not maintained climb power when he levelled at 6,000ft, the passing distance would have probably been much less.

The Darwin Approach Controller admitted to misidentifying VH-LLY, contributing to the breakdown in separation standard.

VH-EJM was being operated on dual circuit training on runway 30. A mixture of left and right circuits had previously been flown, with the last one being a right circuit. Stop and go landings were being made. On the last approach air traffic control had instructed the pilot to make the next circuit a left circuit.

VH-FNE was lined up on runway 35 and after VH-EJM had crossed the runway intersection the controller cleared VH-FNE for take-off. On climb the crew of VH-FNE observed VH-EJM to be approaching their flight path, on a right circuit. The climb of VH-FNE was stopped and VH-EJM passed about 200 feet above and slightly behind VH-FNE. The pilot of VH-EJM had seen VH-FNE.

At about the same time as the pilots of the two aircraft saw each other the air traffic controller, who had been looking in another direction at a third aircraft, looked back and saw VH-EJM flying a right circuit and in conflict with VH-FNE. Traffic information was given to VH-FNE and the pilot of VH-EJM was advised of the mistake and to continue with the right circuit.

Significant Factor

The following factor was considered relevant to the development of the incident:

1. Misunderstanding of the instruction to make a left circuit, by the pilot of VH-EJM.

Circumstances

The B737 was operating on airway B580 and had passed waypoint URGUS at 1234 EST maintaining FL350 and was estimating waypoint MULID at 1322. Flight plan estimates indicated that the B737 would cross airway A464 at approximately 1343 and the next waypoint APORA at 1424.

The B74F was operating on airway A464 and had passed waypoint RELIK at 1251 maintaining FL350 and was estimating over Lord Howe Island at 1323. Flight plan estimates indicated that the B74F would cross airway B580 at approximately 1331 and the next waypoint UDIKO at 1401.

At approximately 1254, Brisbane oceanic control sector 8 (Sect 8) relayed a level change requirement instruction through Sydney Flight Service International (FS INT) for the B737 to descend from FL350 to FL330. The instruction was intended to provide separation assurance between the B737 and the B747F.

The level change requirement was notated on the correct flight progress strip but entered in an incorrect information box relating to waypoint URGUS, the waypoint just passed.  The FS INT officer was provided with a temporary relief break at approximately 1310.  The level change requirement had still neither been passed to the B737 nor been included in the handover/takeover to the relieving officer.

At approximately 1328, the relieving FS INT provided Sect 8 with reports for the B737 passing MULID and the B74F passing Lord Howe Island. Both aircraft were still maintaining FL350. Sector 8 realised that the aircraft level change instruction had not been issued and that lateral separation standards had been infringed.

Due to the prevailing poor communications propagation conditions, FS INT was unable to re-establish contact with the B737 until approximately 1336. The B737 then descended to FL330 and crossed airway A464 approximately seven minutes later.

Although the prescribed separation standards were not maintained, there was no risk of collision.

No new safety deficiencies were identified during this investigation.

The approximate track of VH-TAH was direct from Malim to Bindook, maintaining flight level 350. VH-CZV was tracking from Wagga to Cowra at flight level 330 and the tracks of these two aircraft crossed. Due to turbulence the crew of VH-CZV requested a climb to flight level 350. A clearance was given for VH-CZV to climb to flight level 370, with a requirement to reach this level in 15 track miles.

Subsequently, the radar controller realised VH-CZV would not reach this level in time. An instruction was issued to VH-CZV to turn right by 90 degrees. The required separation was not maintained, with the lateral distance reducing to 3 miles when VH-CZV was 1500 feet above VH-TAH. The climb was continued and vertical separation established.

Significant Factors

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

1. Controller technique in allowing insufficient track distance to achieve the level change.

2. Aircraft crew acceptance of the requirement and then not advising they could not achieve the required level in time.

3. Slow recognition by the controller that the climbing aircraft would not reach the required level in time.

VH-LJD was inbound to Canberra from the north-east at 3500 feet. VH-NNC departed from runway 30 at Canberra and made a right turn on climb to 4000 feet, tracking to the east. The tracks of the two aircraft crossed. Subsequently VH-NNC was cleared to climb to 7000 feet.

An actual altitude obtained from the pilot of VH-NNC indicated the mode C read out of altitude was 500 feet low. The pilot was told of this, and air traffic control used the pilot altitude reports for the separation of VH-NNC from VH-LJD.

After the two aircraft had passed the pilot of VH-NNC advised that he had misread his altimeter and that the mode C altitude was in fact correct. At the time the two aircraft passed the vertical separation by radar was 200 feet.

Significant Factor

The following factor was considered relevant to the development of the incident:

1. The pilot of VH-NNC misread his altimeter.