VH-OJJ had departed Cairns and was climbing through Flight Level (FL) 120 when it received a TCAS (Traffic Alert and Collision Avoidance System) warning. The subject of the alert was P2-AND, which was on descent inbound to Cairns from the north-east. Both aircraft took avoiding action, with VH-OJJ following the Resolution Advisory directions of the TCAS and adopting a descent. The crew of P2-AND saw VH-OJJ and arrested their descent. The closest point of approach between the two aircraft was 1.14 NM laterally and 900 ft vertically. Both aircraft were under radar control by Cairns Approach at the time. The minimum separation standard under these circumstances is 3 NM laterally or 1,000 ft vertically. The Approach Control console was manned by a controller who was being refamiliarised by another rated air traffic controller, following a period of absence. VH-OJJ had departed Cairns via a SID (Standard Instrument Departure) that left the aircraft on a climb-out track of 020 degrees. During the SID, the clearance was amended to allow the aircraft to track direct to the first enroute reporting point at AKTEL. The aircraft turned and tracked about 330 degrees to comply with the amended clearance. The supervising controller advised the operating controller that the track adopted would, in his opinion, not provide enough separation with P2-AND. The operating controller then gave VH-OJJ a heading of 330 degrees to steer. The supervising controller allowed the situation to continue as the aircraft were still separated by some 25 NM, expecting the operating controller to take adequate steps to resolve the potential confliction. Approach Control was busy, having approximately 10 aircraft on frequency with several awaiting clearance to enter the control zone. When the supervising controller saw that a confliction was imminent, if the two aircraft continued on their present headings, he told the operating controller to turn VH-OJJ to the right, expecting a significant turn onto 020/040 degrees. However, because of radio transmissions from other aircraft, some 20 seconds elapsed before the controller was able to instruct VH-OJJ to turn to a heading of 360 degrees. As VH-OJJ straightened on the new heading, the TCAS Resolution Advisory warning was received by the crew. The control technique used by the operating controller, and allowed to continue by the supervising controller, was flawed because it left the two aircraft in conflict from the time the crew of VH-OJJ was instructed to steer 330 degrees. The controller had the option of using a fail safe technique by turning VH-OJJ early and further so that it would pass behind P2-AND. The option of applying altitude restrictions on both aircraft to achieve vertical separation was not considered. During the sequence, the supervising controller was sitting behind and to one side of the operating controller. He was provided with a facility to listen to communications but was unable to directly issue instructions to aircraft. The supervising controller was surprised at the small turn given to VH-OJJ when the confliction was imminent, but it was then too late to take action. Later he said that he should have taken action earlier but the controller at the console was more experienced in the position. As a result, he was reluctant to interfere with the other controller's method of operation. Prior to this shift, the operating controller had been absent from work for 25 days. This period included recreation leave followed by sick leave. Unbeknown to his shift supervisor, he was under considerable stress due to illness in his family, and had not fully recovered from influenza. Refamiliarisation can be undertaken under the supervision of any rated controller, even if the latter has only himself or herself just been rated. Other training is carried out by a training officer who has at least six months experience in the position or has received training in instructional techniques. A refamiliarisation officer is not required to have received training in instructional techniques. SIGNIFICANT FACTORS 1. The operating controller was unfit for duty due to his own illness and stress caused by family problems. 2. He did not inform his supervisor of the problems. 3. The supervising controller did not take timely action to resolve the confliction. 4. The operating console was inadequate for training/familiarisation in that there were no facilities for the supervising controller to communicate directly with aircraft. SAFETY ACTION During the course of the investigation the Bureau issued the following recommendation R930236: It is recommended that the Civil Aviation Authority include complete and comprehensive documentation on the operation of TCAS in the Manual of Air Traffic Services and Australian Aeronautical Information Publication to provide: (i) flight plan, progress strip and radar data tag indications when serviceable TCAS equipment is carried. (ii) samples of unambiguous phraseology for aircrew to notify only TCAS TA and RA events to ATS. (iii) samples of unambiguous phraseology for aircrew to use when diverting from and resuming flight profiles following an RA event. A reply was received from the Civil Aviation Authority which stated, in part: 'The general comments on TCAS have been noted and are confirmed by our own information. I also advise that the recommendations listed have already been acted upon or are in the process of activation. The Civil Air Operations Officers' Association of Australia have expressed the view that they are "convinced that the carriage of TCAS should be the subject of specific flight plan notification" and "that notification should be displayed for controller reference". (U.S. controllers receive flight plan notification and the information is also shown on radar data tag and/or flight progress strip.) District Offices have been asked for comment on the inclusion of the ICAO statement in MATS or otherwise given the Civil Air and BASI position. Copies have been made of 2 videos; the first deals with the operation of TCAS from a pilot's perspective (30 minutes) and the second deals with the controllers side (10 minutes). Both were produced by the FAA. These videos have been distributed to the CAA District Offices for controller education. "Standard phrases" both for pilots and controllers are being devised for inclusion in AIP and MATS. It is expected that these phraseologies, which are based on UK CAA and FAA phrases in use, will be included in the next AIP/MATS amendment. In conclustion it is agreed that it is important to raise both pilot and controller awareness of TAS. and the effect that it will have.' Other deficiencies identified during this investigation, including console modification and training considerations, are being analysed in order to formulate appropriate safety actions.