The pilot of the Sikorsky S76 helicopter reported that while approaching Barrow Island and immediately after he reduced the helicopter's airspeed for landing gear extension, he found that the cyclic could not be moved aft. He also found that with any further forward movement of the cyclic stick, the stick then could not be moved aft of the new position. The pilot froze the cyclic longitudinal position and the helicopter stabilised in a level pitch attitude at about 85 kts indicated airspeed. Using only lateral cyclic movements to manoeuvre the helicopter, the pilot conducted an 80-kt run-on landing on the runway at Barrow Island.

The subsequent maintenance inspection found a panhead type screw at the base of the cyclic stick. The screw had lodged between the lower protrusion on the casting on the end of the cyclic stick torque tube and the lugs on a support bracket. The lodgement of the screw in that location had caused the cyclic restriction experienced by the pilot.

The cyclic stick base hardware was accommodated in a tub-like area formed by the cabin structure supports. A leather boot mounted at the base of the cyclic normally prevented foreign objects from entering the tub. The subsequent maintenance inspection found the leather boot on this helicopter to be intact. With the boot in place, the only possible entry points where a screw could be inserted was through a rigging pin hole in the aft mid-height position of the boot-halves joint, or vertically through an opening provided for the cyclic stick electrical wiring loom. Due to the unlikelihood that a screw could enter the tub area when the boot was fitted, the screw was probably introduced to the area during prior maintenance while the boot was removed.

The pilot of the Chipmunk did not see the Metroliner. It is likely that the pilot commenced his take-off roll when the Metroliner was at least 3 NM from touchdown. At that distance, the Metroliner may not have been readily detectable by the Chipmunk pilot. His lookout for possible traffic would most likely have been directed towards the circuit and approach of runway 03 rather than towards runway 21 and he would not have been expecting to see traffic approaching from the opposite direction. With the aircraft in the level attitude during take-off, he would have been looking along the runway and his attention would have been focused on maintaining directional control. The Metroliner would most likely have been obscured from the Chipmunk pilot's view by the nose of his aircraft when he subsequently rotated to the climb attitude.

The crew of the Metroliner did not see the Chipmunk until that aircraft was almost overhead theirs. As they had not received any response to their broadcasts on the CTAF, they were relying on visual acquisition of any unalerted traffic as their only defence against a conflict. However, the Chipmunk was a small visual target with little relative movement. In addition, it had no anti-collision lighting and would initially have been below the Metroliner crew's horizon. The contrast between the background and the colour of the Chipmunk was minimal and would have made the aircraft difficult to discern.

The straight-in approach procedure at CTAF aerodromes did not appear to adequately address the limitations of unalerted "see and avoid" principles. The assumption of two pairs of eyes being more likely to detect unalerted aircraft than one pair of eyes, did not prove to be an adequate defence in this incident.

In this instance, the crew of the Metroliner elected to make a straight-in approach in wind conditions that most probably favoured a reciprocal runway direction. Without any response to their broadcast intentions, the crew probably assumed that there was no traffic and believed it was safe to use runway 21. As regulations in force at the time of the occurrence did not include a requirement for an airline operator to assess the circumstances and the likelihood of encountering non-radio traffic at individual locations, it was likely that many crews were conducting straight-in approaches as an expected routine. Had the crew been aware, for example, of the potential for greater numbers of recreational movements at weekends and on public holidays, they may have decided not to conduct the straight-in approach.

Although the company had provided a radiocommunication service to comply with the requirements for this procedure, its effectiveness to alert the crew to other aircraft was restricted by company procedures and by the physical location of the radio operator. The radio operator was not familiar with aircraft movements and had never been instructed to provide runway-in-use information. Had the radio operator been afforded a full view of the entire runway and the approach path of the Metroliner and permitted to issue traffic information, a timely warning may have been broadcast to the crew of the Metroliner about the presence of the Chipmunk.

The pilot of the Chipmunk chose to continue his flight without radio communication and without knowledge of a procedure that could place him in potential conflict with a passenger-carrying aircraft. Knowledge of scheduled aircraft movements at that location may have influenced the pilot to avoid commencing a non-radio flight when the arrival of a scheduled service was imminent.

Sequence of events

The crew of a Metroliner, conducting a scheduled passenger service from Sydney, reported that at 30 NM from Latrobe Valley, they obtained weather information from their ground agent on the common traffic advisory frequency (CTAF). They recorded the wind as light and variable. At approximately 17 NM, the co-pilot broadcast on the CTAF advising their intention to join for a 5 NM straight-in approach to runway 21. Two similar broadcasts were made, one at 10 NM and the other at 5 NM. At approximately 1 NM from touchdown, the crew saw a Chipmunk aircraft a short distance to their left and about 400 ft above them, travelling in the opposite direction. The crew continued their approach and landing as they considered that there was no further risk of collision.

The Chipmunk pilot was conducting a private flight. He reported that the aircraft radio had undergone maintenance prior to the incident flight and that he was unsure if a functional check of the radio had been made. He determined that the wind was a light north-easterly and elected to use runway 03. He broadcast on the CTAF that he was taxiing, and made a further transmission advising that he was backtracking along runway 03. He did not hear any response to either broadcast and had not heard the aerodrome frequency response unit. He assumed that his aircraft radio was not operating and proceeded with the flight without making any further radio broadcasts.

The pilot of the Chipmunk reported that he did not see any aircraft either when entering the runway or when lining up for takeoff. He departed and climbed away, unaware that the landing Metroliner had passed below him. Although he was aware that scheduled flights operated into the aerodrome, he was not familiar with those schedules. He was also unaware that such aircraft could conduct straight-in approaches to CTAF aerodromes. He reported that although his aircraft was equipped with a landing light, he was not in the habit of using it in daylight conditions.

Witness information

An instructor at the aerodrome reported that, at the time of the occurrence, the Chipmunk and the Metroliner were the only aircraft in the circuit. He added that other aircraft movements that day had been made from runway 03.

Following this incident, another instructor observed the straight-in approach procedure under similar conditions. He stationed himself at a position similar to that of the Chipmunk pilot at takeoff in order to determine the visibility of the approaching Metroliner. He reported that when the crew broadcast their 5 NM position, he was only able to see the aircraft after several seconds of looking. However, at an estimated 3 NM, with the landing gear extended and the taxi light illuminated, it was much easier to see the aircraft.

Weather

Weather conditions at the time of the occurrence were described as fine and clear with good visibility. Witnesses on the ground reported the wind as 5-8 kt from the north-east. Data recorded from the automatic weather station (AWS), indicated that a north-east wind had prevailed from 1100 Eastern Standard Time (EST) onwards. The Latrobe Valley METAR (meteorological observation) at 1304 EST indicated that the wind direction was 070 degrees magnetic and the windspeed was 7-10 kt. Those conditions favoured the use of runway 03.

Straight-in approach procedures

On 26 March 1997, the Civil Aviation Safety Authority permitted multi-crew regular public transport aircraft to conduct straight-in approaches to non-controlled aerodromes other than those within a mandatory broadcast zone. Effective from 1 May 1999, amendment 35 to the Civil Aviation Orders (CAO) part 82.3 incorporated a new sub-section 5A that required the provision of a ground-based radiocommunication service at aerodromes where straight-in approach procedures were conducted. However, following industry concerns about the operator's liability in relation to the provision of traffic information and the cost to airlines of providing such a service, that section was amended. CAO amendment 41 was issued with a new sub-section 5B that restricted the information to be given by the radiocommunication service to wind direction and runways in use at the aerodrome.

The company operating the Metroliner contracted the services of a ground-handling and booking agent to perform the required radiocommunication service, and personnel were trained and approved to provide that service. The procedure required the agent's staff to obtain weather information from the AWS and, when requested, broadcast this information to company pilots on the CTAF. Information about other traffic or the runway in use was not transmitted.

The agent advised that crews could obtain traffic and runway information from other aircraft on the CTAF. Other duties performed by the agent's staff precluded them from continuously monitoring the CTAF for information about other traffic. Additionally, the company radio was situated in the airport terminal and only a limited view of the airfield was afforded through the windows. Visual observation of aerodrome traffic from this location was not possible. The Chipmunk would not have been visible from this vantage point at any time it was taxiing or airborne.

There were no specific company instructions for crews making straight-in approaches at CTAF aerodromes. Company management personnel were satisfied that the procedures contained in the Aeronautical Information Publication were adequate. Company standard operating procedures required the landing and recognition lights to be turned on as aircraft were approaching 10,000 ft when transition checks were being completed. The taxi light was not to be turned on until after the landing gear was extended. The crew reported that that procedure had been followed.

The pilot in command advised that the crew's preferred choice of runway direction at Latrobe Valley on the flight from Sydney was runway 21. This not only reduced flying time but also allowed crews the 3-minute cooldown period for the engines while backtracking to the terminal. It also avoided running the engines near the terminal and creating unnecessary noise.

Determination of the runway in use, as required by the Aeronautical Information Publication (AIP) procedure, was assumed by crews to be either the reported runway being used by other traffic in the circuit or, in the absence of other traffic, runway 21, provided that wind conditions were favourable. The view expressed by the pilot in command was that the straight-in approach procedure offered a better level of safety than that provided by the normal circuit entry and that it was more expedient. He believed that the procedure resulted in less circuit manoeuvring and a reduced risk of traffic conflicts.

Aerodrome traffic

This incident occurred on a Sunday afternoon. The airline operated six services per week into Latrobe Valley but only one of these flights was conducted on a weekend. The pattern of activity at the aerodrome was not recorded however, staff at the Aero Club were able to confirm that most recreational flying activity took place at weekends and on public holidays. Only a small number of aircraft operating from the aerodrome were not radio-equipped. The scheduled movements at Latrobe Valley were not published in any of the aeronautical publications.

1. The approach controller used the "sight and follow procedure" in an inappropriate circumstance. That is, the controller transferred the responsibility for separation to the pilot in a situation where the positive application of a separation standard may have been more appropriate.
2. The approach controller requested the crew of the Metroliner to sight the Jetstream in circumstances where a positive sighting may have been improbable.
3. The crew of the Metroliner sighted and followed the BAe 146 rather than the Jetstream

Notwithstanding the different profiles of the two aircraft, type identification of either aircraft would have been virtually impossible to determine at the ranges of the aircraft, that is beyond 6.8 NM. This is because contrast, which is the difference between the brightness of the aircraft against the brightness of the background, reduces with increasing range. Further, target identification would have been hampered by contour interaction. This phenomenon occurs where the outline of a target aircraft interacts with the contours present in the background. This is a particular problem at lower altitudes where aircraft appear against complex backgrounds.

When the crew of the Metroliner was instructed to report when they could see the other aircraft at 11 o'clock, the BAe 146 was the only aircraft discernible to them. With its side profile, the BAe 146 was at the extreme limit of visual acuity and could easily have been mistaken for a Jetstream, particularly as no other aircraft was in their field of vision. The Jetstream, with its head-on profile and greater range, would have been impossible to see at 9.8 NM. Moreover, because its actual position was not correctly described to the crew, they were looking for the Jetstream in the wrong place.

The approach controller may have realised that there was potential for mis-identification of the two aircraft. This is suggested by his action of cautioning the Metroliner crew about the BAe 146 that was on short final. However, the controller did not provide additional information that would have provided an assurance that the pilot was following the correct aircraft.

The identification of the potential conflict and action taken by the aerodrome controller was timely and appropriate. The vigilance and prompt action of the aerodrome controller acted as a safety defence to reduce the possibility of collision between the aircraft.

There were three aircraft in the approach sequence to land on runway 19 at Brisbane: a British Aerospace 146 (BAe 146), VH-JJS, on final at 2 NM; a British Aerospace Jetstream 3200 (Jetstream), VH-XFC, on right base at 6.5 NM with approximately 8 track-miles to touchdown; and a Fairchild SA226 Metroliner (Metroliner), VH-TFQ, on an oblique left base at 6.5 NM with approximately 10.5 track-miles to touchdown. Analysis of recorded voice data confirmed that the approach controller advised the crew of the Metroliner that they were number 3 in the sequence and that the Jetstream was number 2. Subsequent to that advice, the controller advised the Metroliner crew that the aircraft they were to follow was at 11 o'clock, 10 NM at 1600 ft. They were instructed to report when they could see that aircraft. The crew responded "Traffic sighted". The crew of the Metroliner was then assigned responsibility for separation from the Jetstream by being cleared to manoeuvre as required to make a visual approach and to "follow the Jetstream". In the same transmission, the crew were cautioned about the BAe 146 "on a very short final runway 19" and instructed to contact the tower.

When the crew transferred to the tower frequency, the aerodrome controller realised that the Metroliner was following the wrong aircraft, the BAe 146, and could be in conflict with the Jetstream. The controller instructed the Metroliner crew to orbit their aircraft on left base to increase its separation with the Jetstream. Analysis of recorded radar data indicated that separation between the Metroliner and the Jetstream had reduced to 1.2 NM when they were at the same level.

The crew of the Metroliner did not recall being cautioned about the 146. The aircraft they had sighted and followed was not the Jetstream but the BAe 146, which resulted in the breakdown of separation.

The Manual of Air Traffic Services (MATS) stated in MATS 4-5-1, paragraph 7:

"Correct identification of the aircraft from which separation must be maintained is essential".

Paragraph 10 stated:

"The traffic information provided shall contain as much as is necessary of the following to assist the pilot in identifying the other aircraft:

1. type, and description if unfamiliar;
2. level;
3. position information either by clock reference, bearing and distance, relation to a geographical point, reported position and estimate, or position in circuit;
4. intentions, or direction in flight."

Analysis of the radar data indicated that at the time the crew was asked to report sighting the aircraft, the BAe 146 was in the Metroliner's 11 o'clock relative position at 6.8 NM and displayed an oblique, side profile. The position of the Jetstream was more to the Metroliner's 12 o'clock relative position, at 9.8 NM and displayed a head-on profile.

On the day of the accident, the pilot had been flying the aircraft at low level for most of the day, with minimal rest periods. He had only recently qualified for his private pilot licence and a significant portion of his total flying hours had been accumulated in the 9 days before the accident. During this period, he had exceeded the flight and duty times normally permitted for a commercial operation.

Fatigue can diminish human performance, particularly with tasks requiring sustained attention and rapid reaction times. It may impair a pilot's ability to judge distance and speed, and it increases reaction times. It may also lead to poor decision making. Heat, noise and vibration may exacerbate these effects.

A human factors report noted that the pilot had worked long hours in a job in which he was inexperienced and that he probably found this type of flying both physically and mentally demanding. The report concluded that at the time of the accident the pilot was suffering from the effects of fatigue, possibly impairing his ability to safely operate the aircraft. The pilot was not qualified to conduct mustering or low flying operations. Without such qualifications, the pilot was legally required to operate no lower than 500 ft above ground level. At this height, the aircraft may have been of some use in spotting sheep but probably would have been ineffective at mustering.

The pilot had received minimal training to identify the visual illusions associated with low level flight. As such it was considered unlikely he was aware of appropriate techniques to safely manoeuvre the aircraft at low level. Several visual illusions affect pilots of low flying aircraft. An untrained pilot would be particularly susceptible to such illusions, some of which may prevent correct estimation of airspeed or making appropriate control inputs during a critical phase of flight.

The property owners had little aviation experience to help them manage the hazards of this type of operation. Although one of the owners knew that pilots needed special training for mustering, the accident pilot was employed while still unqualified.

Pilot fatigue, a lack of low flying training and no appropriate supervision of a relatively inexperienced pilot were identified as possible contributing factors to the accident. The immediate circumstances of the aircraft impacting the ground could not be established.

The Cessna 172 was being used to assist a ground party of station hands to muster sheep on a station property approximately 46 km south-west of Onslow, WA. As a result of the accident the pilot sustained fatal injuries and the aircraft was destroyed.

1. The similarity of the departure instruction to the noise abatement procedure provided the potential for a human error to occur.
2. The crew of TAF did not comply with the departure instruction issued by air traffic control because the crew confused the instruction with the noise abatement procedure.
3. The enroute controller did not issue TAF with a procedural clearance that would have provided separation assurance with CZV.

The investigation determined that the crew of TAF did not comply with their departure instruction. Separation would not have been infringed if TAF had continued on a heading of 090 M as directed, instead of intercepting the 128 radial. The similarity of the noise abatement procedure to the departure instruction may have diminished the importance of the requirement for the crew to maintain a heading of 090 M after departure.

Although the action of the crew resulted in an infringement of the radar separation standard, the enroute controller did not issue a clearance that assured separation between TAF and CZV. Separation assurance was required in accordance with MATS 4-1-1, paragraph 6. The controller used radar procedures to separate the two aircraft, where non-radar separation should have been applied in accordance with MATS 4-1-1 paragraph 11 because communications and equipment did not allow the application of radar separation.

The enroute controller was not in direct communication with the crews of both aircraft. Moreover, portions of Maroochydore airspace were below radar coverage including airspace below 1,500 ft. Although LOA 98/054 allowed the enroute controller to "assume radar identification of departing aircraft within four minutes of the next call", published procedures did not permit the enroute controller to apply radar separation between radar identified aircraft and aircraft departing Maroochydore that were not identified.

The crew of VH-TAF, a Boeing 737, was taxiing for runway 18 at Maroochydore (MC) for a departure to Sydney. The route was flight planned, and subsequently cleared, via waypoint TRIKI (128 MC at 22 NM) on air route W196 at flight level (FL) 350. The crew had pre-briefed the noise abatement procedure that was detailed in AIP Australia as follows:

"2.2 Departing Runway 18 - MC to TRIKI: UNLESS OTHERWISE DIRECTED BY ATC. (a) Jet aircraft shall at 500FT, turn left heading 090 degrees M to intercept track. If not able to intercept track from this heading, then maintain heading 090 degrees until 4DME before turning to intercept track".

Another Boeing 737, VH-CZV, was inbound to Maroochydore from Sydney and tracking via TRIKI on W196. The Maroochydore aerodrome controller had received prior coordination on this aircraft, which was on descent to 5,000 ft. Although the BURNET enroute controller was responsible for CZV, the crew was not in two-way communication with the enroute controller. The enroute controller had agreed to allow the crew to transfer frequency direct from Brisbane Approach to Maroochydore Tower. The standard frequency transfer point in accordance with Letter of Agreement (LOA) ND 98/054 was TRIKI. CZV was roughly 32 NM from Maroochydore when the aerodrome controller contacted the enroute controller to coordinate a departure clearance for TAF.

Maroochydore was a non-radar tower and the aerodrome controller was responsible for providing procedural separation to aircraft below 4,500 ft. The enroute controller was responsible for the surrounding airspace overlying and to the south of Maroochydore as defined in the AIP Designated Airspace Handbook. The enroute controller was able to use radar or procedural means to provide air traffic control separation. Radar coverage in the Maroochydore area was generally available above 1,500 ft.

At 1236, the enroute controller advised the aerodrome controller to issue TAF a heading of 090 degrees M and to maintain FL150, a level that would provide vertical separation from a third aircraft overflying at FL160. The aerodrome controller recognised a potential conflict between TAF and CZV, and confirmed with enroute that the enroute controller would accept the responsibility for conflict resolution. The enroute controller accepted the responsibility for providing separation.

The aerodrome controller then issued the following departure instruction to the crew of TAF: "TAF, restriction on departure is to turn left and take up a heading of 090 magnetic, maintain FL 150, clear for take-off, make left turn". The crew correctly read back the instruction. The crew later reported that they interpreted the restriction on departure to be the altitude restriction and believed the heading instruction applied to the noise abatement procedure. At 1238, the crew was instructed by the aerodrome controller to contact the enroute controller to make a departure report.

CZV meanwhile, was approaching TRIKI and the crew reported to the Maroochydore aerodrome controller on descent to 5,000 ft. The aerodrome controller directed the crew to continue tracking direct to Maroochydore and to maintain 5,000 ft. Maroochydore tower then contacted the enroute controller seeking an unrestricted descent clearance for CZV, which was granted but not issued to the crew.

At the same time, TAF was turning right to intercept the 128 radial at 4 NM from Maroochydore and was passing 4,400 ft on climb. The crew contacted the enroute controller at 1239 and reported established on the 128 radial, climbing to FL 150. TAF and CZV were then on reciprocal tracks and closing. In an unsuccessful attempt to preserve the required separation, the crew of TAF was told to turn left onto a heading of 090 M and maintain 5,000 ft. The aerodrome controller who was in two-way communication with the enroute controller over the hotline, found that CZV was passing 5,400 ft on descent. The enroute controller asked the aerodrome controller to direct the crew of CZV to turn right on to 090 M, which was actioned. The enroute controller issued traffic information to the crew of TAF about the relative position of CZV and requested the crew to climb to FL 150 and maintain their best rate of climb. Traffic information was not issued to the crew of CZV about TAF.

At 1240, the required vertical separation of 1,000 ft between the two aircraft reduced to 400 ft when the minimum radar separation of 5 NM was infringed. The application of radar separation and the requirements for issuing clearances were detailed in chapters 4, 9 and 12 of the Manual of Air Traffic Services (MATS).

The enroute controller received a short-term conflict alert (STCA) on the radar display. However, neither of the flight crews reported receiving a traffic alerting and collision avoidance system (TCAS) warning from their respective aircraft's display.

1. The supervisor of the trainee, the aerodrome controller, had a lapse in concentration at a critical stage of the departure sequence, having been operating at the position in excess of 3 hours.
2. The trainee was unfamiliar with terminal area operations/procedures and was unaware of the increase in complexity during runway transition.
3. Tower training publications' critical safety section and other references did not include potential standard instrument departure or arrival areas of conflict.

The concentration level of both the aerodrome controller and the trainee had probably lapsed due to the duration of the training session. Additionally, the aerodrome controller may have been less vigilant in his monitoring of the trainee because of the reduction in aircraft numbers and his perception of the trainee's level of competence in the aerodrome control position.

Provision of information regarding the increase in complexity of traffic management during runway transition and regarding the critical safety aspects of standard instrument departures and arrivals would have provided the trainee with some knowledge to compensate for areas where he lacked experience. On-the-job training does not necessarily expose trainees to all critical elements nor provide sufficient time for them to develop their own traffic management models. Information on such critical areas is required to ensure that safety aspects are understood and considered, particularly during on-the-job training.

A greater awareness of terminal area operations and procedures may have provided the trainee with sufficient knowledge to appreciate that the departing aircraft were not going to be separated by the departure controller. In turn, this may have alerted the trainee to the fact that he was required to provide a separation solution or alternatively coordinate one with the departure controller.

A Beech 1900 (Beech) departed from runway 27 and was tracking via a STRATHBOGIE 8 standard instrument departure, on climb to 5,000 ft. Shortly after, a Boeing 767 (B767) departed from runway 34 on a DOSEL 8 standard instrument departure, on climb to 5,000 ft. The standard instrument departure tracks intersected approximately 2 NM north of the aerodrome. The departure north radar controller (departure controller) observed that the separation between the two aircraft was not going to be maintained and queried the aerodrome controller in relation to the separation procedure being applied. The aerodrome control position was being operated by a trainee under the supervision of a rated controller. The trainee advised that he thought the departure controller was providing separation. The departure controller instructed the Beech crew to turn left onto a heading of 310 degrees and the B767 crew to turn right onto a heading of 030 degrees. The two aircraft passed at the same altitude, with 1 NM lateral separation. The minimum separation required was either 3 NM laterally or 1,000 ft vertically. There was an infringement of separation standards. The B767 was fitted with a traffic alert and collision avoidance system and the crew received a traffic advisory just prior to the issue of the avoiding instructions from the departure controller.

The trainee and the aerodrome controller had been at the console for about 3 hours and the number of aircraft being managed had reduced slightly following a busy period. The runway mode was being changed from land and hold short operation (LAHSO) using runways 34 and 27, to dedicated departure runway arrangement using those runways. In LAHSO all aircraft depart from runway 27, while in the dedicated departure mode, departures to the south and west use runway 27 and those to the north and east use runway 34. In that configuration, the intersection of aircraft departure tracks is almost eliminated. It was recognised by experienced controllers that the transition period between runway modes required an increased awareness and careful consideration of the traffic management plan to ensure that potential conflicts for departing aircraft were minimised. The trainee was aware of potential problems for each mode but had not been alerted to the potential problems that may occur during a mode transition period. On taxi, the crew of the B767 requested and were approved to use runway 34. The trainee subsequently amended the departure order of the B767 and the Beech to eliminate a requirement to apply a 2-minute wake turbulence separation standard to the Beech aircraft.

The trainee did not appreciate that the aircraft's departure tracks converged north of the aerodrome. The aerodrome controller reported that as the trainee was soon to be checked for a rating his monitoring of the trainee's control was less vigilant than normal. Local instructions stated that the aerodrome controller was responsible for the separation of departing aircraft within 5 NM of the aerodrome and that for departures from different runways, the aerodrome control and departure control positions were jointly responsible for coordinating a separation solution. The departure controller's preference was to depart the B767 before the Beech but he agreed to the trainee's request to change the departure order. Normal practice in this situation was that the aerodrome control position, having initiated the change, was responsible for the separation unless otherwise coordinated. The controllers neither coordinated a separation solution nor clearly established who was responsible for ensuring separation. Both assumed that the other was going to separate the two aircraft. The aerodrome controller was not aware of the developing situation and was only alerted to the infringement following the departure controller's query to the trainee.

The trainee had undergone tower control ab initio training, which included approximately 1 day of training on the vectoring of aircraft. The course did not provide any terminal area (TMA) control training. Controllers undergoing training for tower positions were able to undertake TMA familiarisation. But the tower training syllabus did not require trainees to develop an understanding of, or to be familiar with, TMA operations. TMA familiarisation by tower trainees was conducted on an ad-hoc basis and there was no procedure to assess a trainee's level of understanding of TMA operations.

Melbourne Tower training publications did not provide advice of a preferred duration for training sessions that would maximise the training benefit. The publications did list aspects of critical safety that needed to be covered during training for both trainees or supervising controllers. But the list did not include areas of known conflict for standard instrument departures or standard arrival routes. The publications did not include advice of the potential inherent complexity of runway mode transition.