The crew of a departing Boeing 737 (B737) reported that as they were climbing to 5,000 ft on a standard instrument departure from runway 27 at Melbourne, they saw an arriving B737 on descent in their 12 o'clock position, passing from right to left. The departing aircraft's traffic alert and collision-avoidance system indicated that there might have been less than the required radar separation standard of 3 NM between the two aircraft. The crew was not alerted by air traffic control regarding the arriving B737.

Radar data and air traffic control automatic voice recordings were reviewed to establish the sequence of events. The investigation found that the Departures controller had assigned responsibility for separation to the pilot of the arriving B737, which was tracking for left downwind runway 34. The transmission from air traffic control to the crew of the descending B737 included the statement "...clear of the 737 out to your left, descend to 3000".

Airservices Australia advised that the procedure was used when separating runway 27 departing aircraft from arriving aircraft tracking on left downwind for runway 34. The aim was to release the climb and descent restrictions of both aircraft as soon, and as efficiently, as possible. The procedure of one aircraft sighting and confirmed past the other aircraft was considered to be a legitimate technique in such situations.

Visual separation of air traffic may have been a valid method to use in those circumstances. However, the criteria for its application were clearly detailed in the Manual of Air Traffic Services (MATS) Part 4 Section 5. In particular, MATS 4.5.1.11 stated: "In circumstances where an aircraft has been instructed to maintain separation from, but not follow, an IFR aircraft, traffic information shall be issued to the IFR aircraft, including advice that responsibility for separation has been assigned to the other aircraft". The departing B737 was an IFR aircraft but was not provided with the required traffic information.

Sequence of events

As the crew of the Boeing 747-438 applied take-off thrust to begin a flight from Sydney to Los Angeles, a noise described as "similar to an engine stall" was heard by all on the flight deck. After an immediate check of engine parameters revealed no abnormal indications, the crew elected to continue the take-off and subsequently heard no similar noises.

During the climb phase of the flight, the Cabin Services Director advised the flight crew of a small area of damage to the right outboard trailing edge flap. The first officer then inspected the area and reported that he believed that the damage was the partial delamination of the composite flap section. All engine parameters, including vibration levels were subsequently rechecked and found to be normal. After discussions with ground maintenance personnel, the crew decided to continue the flight.

On landing at Los Angeles, inspection of the aircraft by ground staff revealed the loss of both left and right combustion fairing panels from the number-three engine. Indentation and scraping damage was found on the internal surfaces of the bypass airflow nozzle behind the combustion fairing. The damage to the trailing edge flap was limited to the area immediately behind the number three engine.

On the morning following the departure, while conducting a routine runway inspection, Sydney airport staff recovered four large aircraft parts from the undershoot area of runway 34L. Further items, including small fragments of composite material, clevis couplings and metal strips, were subsequently found during a walking inspection of the runway undershoot area.

Inspection of the items by the operator's engineering personnel confirmed the items to be the missing fairing panels from the Boeing 747.

Technical examination

The ATSB examined the items recovered from the runway to determine how they separated from the aircraft. The left and right combustion fairing panels were both extensively damaged, with the larger right panel having broken into two sections. Both panels showed evidence of having forcibly struck the internal surfaces of the engine nozzle assembly before being ejected to the rear by the bypass airflow of the accelerating engine.

The fairing panels were mounted onto the engine by a row of three hooks that engaged with recessed pins on the upper panel section. When mounted, the panels latched together at the base of the engine using an adjustable hook and clevis. A study of the fairing panel mounting and latching points showed evidence that the right panel was not engaged with the upper panel at the time it was ejected from the engine. All three mounting hooks were undamaged and showed no sign of having been forcibly pulled away from the upper fairing pins. In comparison, both latches and the forward hook from the left panel showed damage consistent with the connections being overloaded and pulled apart.

Damage to the trailing edge section of the right centre wing flap was consistent with an impact with the ejected combustion fairing panels. Witness marks pointing to a forceful impact surrounded the area of damaged composite material along the edge of the flap section.

Technical analysis report number 18/01 refers to this part of the investigation and is available on the ATSB website or from the Bureau on request.

Assembly examination

The engine from which the fairing panels were lost was a Rolls-Royce RB211-524 model. The panels were part numbers UL26239 (right) and UL26237 (left), with the manufacturers illustrated parts catalogue identifying both items as made to incorporate service bulletin RB.211-72-4647. The manufacturer introduced bulletin 4647 in 1977 to combat combustion (gas-generator) fairings detaching because of incorrect fitting.

Examination of the fairing assembly during installation confirmed that it was possible to place the fairing panels in position around the engine without engaging the upper mounting hooks. The clamping action of the interlocking fire seal along the rear edge of the fairing panels allowed the items to stay in position without the support of the hooks. Latching action between the fairing panels was also unaffected.

When the panels were installed incorrectly, inspection of the upper connection points clearly showed a large gap between the upper and side fairings. Inspection of that area was difficult because of the restricted confines of the cold stream duct surrounding the panels. Platforms for use within the cold stream duct were available, however comment from maintenance personnel suggested they were rarely used. Testing the platforms showed a degree of instability in use and further restricted the access to the lower areas of the duct. Latching the fairing panels together with the platforms in place was difficult. The time taken to load, fit and then unload the platform sections, was also cited as a problem for maintenance personnel. The Boeing maintenance manual for the 747-400 aircraft requires the use of access platforms within the cold stream duct.

Maintenance records

Documents provided by the operator showed that the flight from Sydney to Los Angeles was the first flight of the aircraft following release from scheduled maintenance. That maintenance (described as an `A' check) involved several tasks that required the removal and reinstallation of the combustion fairing panels from all engines. A further review of the records relating to the work conducted on the number-three engine showed that a "panels and fairings final fitment check" line item was present in the work instructions. That action was signed-off as completed by a licensed maintenance engineer. The engine had been subsequently ground run for five minutes at idle speeds, with no noted anomalies. Check sheets for the examination of engines after ground running incorporated eight specific inspections, including a check for correct installation and latching of the fairing panels. Those checks had also been signed-off as being satisfactorily completed.

Fitting the combustion fairing panels to RB211-524 engines was the subject of several work instructions produced by the operator. The instructions referred to the operator's minor maintenance manual and the manufacturer's maintenance manual, which provided both written and visual illustrations of how the panels were to be fitted. The need for inspection of mounting hook engagement after installation was also clearly stated, with clear warnings of the potential for incorrect installation and the damage that may result. Requirements for the use of INA (integrated nozzle assembly) access platforms were also included in the latest revisions of the manual, which were issued on February 18, 2001.

Following the Boeing 767 (B767) aircraft's second flight after scheduled maintenance, a pilot maintenance log entry noted that the cabin door L1 slide bustle was hanging down. A line engineer on duty examined and certified that the cause was a weak cable spring. The discrepancy was then placed on deferred maintenance as it was not considered to be an airworthiness defect. The following day, prior to departure, the cabin crew of the aircraft reported the cabin door L1 (forward entry door) bustle was lower than normal. Inspection revealed that the girt bar was not attached to the escape slide girt bar carrier, but was instead in the stowed for maintenance position, rendering the slide inoperative. The line engineer on duty correctly installed the girt bar, thereby returning the L1 door escape slide to operational capability. No maintenance log entry was made concerning the discrepancy, or of the corrective actions.

When maintenance personnel conferred following the L1 door escape slide girt bar rectification, a decision was made to inspect the remaining aircraft door slides for condition. The inspection revealed that cabin doors R1 (forward service door), R2 (rear service door), and L2 (rear entry door) emergency escape slides were inoperative, with the door girt bars also in the stowed position.

Consequently, during 8 and 9 April 2001, the aircraft was operated seven sectors with four cabin door mounted escape slides inoperative. During 9 April 2001, the aircraft was operated one sector with three slides inoperative. If required, the cabin crew could not have successfully activated the escape slides of those doors, nor the automatic opening of the doors during those flown sectors.

B767 cabin door configuration

The cabin door configuration of this aircraft was one forward door and one rear door per side. The doors were arranged in sequential order, numbered from the nose of the aircraft. The doors were identified as per side by lettering indicating `L' for the left side of the cabin looking towards the nose, and `R' for right.

Previous maintenance

Further investigation revealed that the last known maintenance of the escape slides, bustles, and girt bars of doors R1, R2, L1, and L2 was performed sixteen days earlier, during a recent 2C scheduled maintenance check. The C check on B767 aircraft, a major scheduled maintenance check, was performed at 6,000 flight hour intervals, and normally planned for 30 days elapsed time (total days out of service). The incident aircraft was out of service for the 2C check for 41 days.

During that maintenance, the escape slide bustles of doors L1, L2, R1, and R2 were disabled and removed by an apprentice Aircraft Maintenance Engineer (AME) under supervision, to allow repainting, other maintenance in the area, and zone inspections. During disabling and removal of the bustles, the girt bars were removed from the carriers and stowed using special straps on the side of the slide packs.

Door mounted slide normal operation

During normal operation, door arming by the cabin crew would lock the girt bar carrier to the aircraft floor fittings. The girt bar would engage the girt bar carrier, whether the slide was ARMED or DISARMED. The ARMED or DISARMED status of the door-mounted slides was indicated to the cabin crew by witness marks, visible at floor level. The arming witness marks reflected the girt bar carrier position in the floor fittings, not the location of the girt bar itself. Thus, the ARMED indication presented to the cabin crew was the same, whether the girt bar was properly installed in the girt bar carrier or stowed on the slide pack.

When a cabin door was unlocked from the inside while in the ARMED condition, the girt bar (engaged with the carrier) initially caused the slide to release from the door. The unladen door would then open under the influence of heavy springs. The subsequent action of the slide pack falling out of the doorway activated the slide inflation sequence.

Door mounted slide operation with girt bar stowed on the slide pack

With the girt bar stowed on the slide pack, each door would have unlocked if opened from the inside in the ARMED condition, however the girt bar carrier would have remained (disconnected from the door) in the floor fittings. The slide pack would have remained intact and attached to the door. The doors would have needed opening manually (as though disarmed), as the emergency auto-opening feature of the cabin door, before slide deployment, relied on the weight of the slide releasing from the door as the door was unlocked. Manual operation was only applicable if the slide had released from the door, but failed to inflate.

Maintenance documentation (removal of the escape slide)

The maintenance facility's normal practice was to use the company's Maintenance Supplementary Report (MSR) form to document tasks involving removal of items from an aircraft for access and inspection purposes. The removal of four escape slide bustles was noted on the aircraft's MSR form for the maintenance event, however, the apprentice who completed the removal of the bustles did not personally document details of the removal in the MSR form. The apprentice did annotate on a Supplementary Report Card (SRC) the bustles removal in accordance with the company's maintenance manual procedures.

The senior Licensed Aircraft Maintenance Engineer (LAME) responsible for the cabin during the scheduled inspection, and supervising the apprentice, stated that his normal practice was to annotate in the Heavy Maintenance Discrepancy Report (HMDR) form, deactivation of the escape slides. On that occasion, he noted the removal of the slide bustles but not the deactivation of the escape slides. There was no evidence that a hand-over log was employed documenting the work.

Installation of the escape slide

Following completion of the zone maintenance in the area of the slides, another apprentice was tasked with reinstallation of the slide bustles to allow the aircraft to be moved outside for engine runs. The engine runs were normally performed three days before maintenance check completion to identify and resolve any engine related anomalies. Normal Heavy Maintenance practices required the slides be installed and operational during engine runs. The slide bustles, including the girt bars, were not completely installed because of on-going work in the area. It was reported that the aircraft's inspection completion was behind schedule by approximately one week.

The bustles of the four doors were partially installed by a second apprentice and annotated on the SRC as completed in accordance with the applicable maintenance manual section. The installation was not completed as per the maintenance manual at that time, as the girt bars were still stowed and the inflation cylinder regulator safety pins were still fitted. No other documentation was utilised to annotate the partial installation.

Post maintenance inspection of the escape slide

According to aircraft maintenance documentation, two LAMEs conducted independent inspections of the slides following maintenance to the slide during the scheduled check. Both conducted and certified the inspection with the knowledge that slide R1 was not yet fully operational. An independent inspection was not carried out for maintenance actions performed on escape slide bustles at the L1, L2 and R2 doors. No additional entries were annotated in the aircraft documentation to note the non-operational condition of the slides.

Prior to release from the 2C check, the B767 Flight Readiness Schedule, an engineering check list, was used to ensure aircraft completion. The check list contained a requirement to check over-wing emergency exits for correct arming, but for door mounted slides the inspection was only to verify that the escape slides were installed.

Human factors issues

The LAME responsible for cabin certification during the 2C check, reported that this was the first time he had been tasked with such duties.

A Boeing 737-476 aircraft was in the final stages of preparation for an 0810 EST scheduled departure from Melbourne. It was the aircraft's first flight of the day. The ground engineer had completed the pre-flight and other assigned pre-departure tasks. There was little else for him to do prior to his duties for the pushback which included assisting the ramp towmotor driver to connect the towbar to the towmotor and walk out with the aircraft. The flight crew had started the Auxiliary Power Unit (APU) and were completing the Before-Start Checklist in preparation for pushback.

The towbar was delivered by ramp personnel at 0803 and was connected to the aircraft nose landing gear by the engineer. At 0805, cargo loading was still in progress in both the forward and rear cargo bays. The engineer was aware that the towmotor should only be driven by the rostered ramp towmotor driver who was still involved with the loading of the aircraft. Concerned that the departure of the aircraft was about to fall behind schedule, he decided to connect the towmotor to the towbar himself.

The engineer moved the towmotor close to the towbar, but stopped when he noticed that the towbar was at the wrong height for connection. He then left the cab, with the towmotor's engine running, to correct the towbar height. While re-adjusting the towbar, he heard the towmotor engine shut down. He reported that he then climbed back into the towmotor, restarted the engine, and attempted to drive forward the remaining 10 cm required for connection.

At that time the towmotor appeared to him to move forward "...relentlessly..." and collided with the aircraft. He indicated that he had applied the brakes and selected reverse gear, without success. He then vacated the cabin of the towmotor across the deroofed front of the vehicle.

The flight crew indicated that they heard and felt a "...big thump..." which continued and shook the aircraft for about 4-5 seconds. The pilot in command advised the cabin crew to "...brace..." and noticed the towmotor wedged under the aircraft nose. He assessed that there was no danger to the aircraft and ordered that the passengers be disembarked normally through the forward door via the aerobridge, which was still in place. He shut down the flight deck systems, set the park brake, but left the APU running to power the hydraulics and disembarked to view the extent of the damage.

The aircraft had sustained substantial damage to the radome, forward pressure bulkhead, forward fuselage skin and nose landing gear doors.

The engineer had been employed by the operator for more than 26 years and was highly regarded as a Licensed Aircraft Maintenance Engineer (LAME) and company employee. Supervisors indicated that the engineer was very cooperative and willing to assist ramp staff at all times to despatch aircraft on schedule.

At the time of the accident, the engineer was on the first day of a shift rotation, having been off-duty for the preceding three weeks.

The engineer held a current ramp driver's licence and had considerable recent experience towing aircraft using another towmotor type. He had last driven the accident towmotor about 6 months previously.

Towmotor and towbar information

The towmotor was designed specifically for B737 use. It had last undergone maintenance action on 5 March 2001. According to the operator's maintenance staff, the accident towmotor was used only on the ramp as it was unsuited for maintenance purposes. It was the only one of its type used by the operator.

The design of the towmotor was such that the towbar and connection point at the front of the vehicle could not be seen from the driver's seated position. Towbar connection was a two-person operation. Any attempt by a single person to connect the vehicle and the towbar, involved the driver having to stand up and lean over the steering wheel to view the operation. From a standing position, it was possible for the driver to place a foot over both the accelerator pedal and the brake pedal simultaneously.

The cabin forward structure had been torn upwards and rearwards during the initial contact with the aircraft. The rear left corner of the cabin structure was forced down through the vehicle's upper body panel by the weight of the aircraft's nose. Inspection of the towmotor found no mechanical fault that could have contributed to the accident.

The towbar for the Boeing 737 aircraft underwent a complete service on 28 March 2001 and had been correctly connected to the nose landing gear strut of the aircraft. Impact from the towmotor sheared the towbar's rear shear pin, which allowed the bar to swivel out of the way, pivoting on the remaining shear pin, as the towmotor drove forward into contact with the aircraft. The towbar was inspected and found to have been serviceable at the time of the accident.

Aircraft pushback procedures

Aircraft pushback procedures at the time of the accident were contained in the operator's Ramp Standard Operating Procedures (SOP). The SOP stated that the towbar was to be delivered to the aircraft by ramp personnel, then connected to the nose landing gear by the engineer. Connection to the towmotor was to be accomplished by the rostered ramp towmotor driver, with the assistance of the engineer. Line engineers normally towed the aircraft for maintenance purposes only. In addition, the SOP stated:

"Use a marshal (usually the engineer) when manoeuvring for hook up to the tow bar when it is attached to the aircraft. Do not stand up to see the hitch point."

The operator's Engineering and Maintenance Procedures Manual stated that:

"...Prior to push-out operation, the engineer will...(2) Connect the towbar and towmotor by front or rear connection as appropriate..."

A ramp driver's licence was valid for a 12 month period. Renewal was devolved to airline operators by the airport owner and consisted of a written examination covering rules, procedures, airfield speed limits and ATC communications and light signals. No driver refresher training was conducted. Company towmotor drivers who were qualified to tow aircraft on the ramp were to conduct towing operations in accordance with their respective company SOP.

Sequence of events

The balloon pilot and his two passengers were conducting a private flight as part of the Canberra balloon festival. The balloon's equipment included three aluminium liquefied petroleum gas (LPG) fuel cylinders, dual burners, three radios, a motorcycle-type lead-acid battery, an altimeter and a variometer. After completing a normal flight, the pilot prepared to land the balloon on an area of parkland. This area was relatively small, with large trees on the approach and a street and houses in the direction of flight. Following the touchdown, as the balloon envelope continued to travel, the basket gradually tipped over and the pilot pulled the ripline to deflate the envelope. At about that time, the occupants of the basket noticed a fireball in the basket and immediately evacuated. Witnesses described the flames as yellow. The pilot stated that he let go of the ripline and allowed the balloon to ascend, deciding that it was safer for the fuel cylinders to be in the air than on the ground surrounded by bystanders. Witnesses heard an explosion and saw an object fall from the remains of the basket. The fire continued to burn, and subsequently consumed the wicker basket and damaged the lower panels and skirt of the envelope. Debris from the balloon fell across three suburbs and damaged several houses. The remains of the balloon were subsequently found 1.6 km from the initial landing point.

The pilot of the balloon was wearing a hat, a short-sleeved cotton shirt, trousers, gloves and shoes. He sustained serious burns to his forearms, face and neck. The male passenger was wearing a woollen lumberjack-style long-sleeved shirt, jeans, gloves, boots, sunglasses and a hat. He sustained minor burns to his face and wrists and was the only occupant not admitted to hospital. The female passenger was wearing running shoes, three-quarter length pants, gloves and a long-sleeved top which did not tuck into the waistband of her pants. She sustained serious burns to her shins and stomach.

Wreckage examination

An examination of the wreckage of the balloon established that two aluminium fuel cylinders were each connected to one of the two burners. One tank was connected by both the vapour feed line and the liquid feed line, while the other was only connected by the vapour feed line. Both pilot-light valves were on, the cross-feed valve was off and both the liquid and vapour offtake valves on both fuel cylinders were on. It was also noted that a male connector fitting had broken off flush with the top of the threaded portion of the body of the corresponding fuel cylinder liquid offtake valve.

Further examination of the broken fitting showed that it had been partially fractured when the fire developed. The fracture was sufficiently large to allow the uncontrolled escape of LPG into the balloon's basket. The fracture surfaces indicated that the fire was no longer burning near the fracture at the time the fitting broke away completely. The fitting had fractured in a downward direction, and there was no evidence of fatigue or pre-existing defects.

One aluminium fuel cylinder was found along the debris trail between the initial landing site and the final location of the remains of the balloon. This cylinder had failed because of a single ductile rupture of the upper shell section, characterised by a large bulged area, outwardly turned fracture lips and extensive blackening and sooting around the rupture.

Pilot light usage

The balloon manufacturer's Flight Manual section 4.6 'Landing', stated that the pilot light should be turned off before touchdown. Some balloon pilots indicated that they sometimes left the pilot lights on for landing if they were certain that the balloon basket would not tip over, allowing them to conduct a go around if required. Once the pilot lights were turned off, if insufficient height was available to relight the pilot lights, a pilot would normally be prevented from conducting a go around before the balloon touched down.

Fuel cylinder fitting selection

The broken fitting consisted of a Rego 8101P5 service valve coupled to a 7141M check connector. With this configuration, the assembly extended outside the fuel cylinder guard ring.

A comparison of the Rego 8101P5/7141M combination liquid offtake valve (left), and the Rego 8180 valve (right), and their relationship to the fuel cylinder guard ring

The balloon manufacturer's maintenance manual stated that "only factory supplied parts and materials are permitted to be used for repair or maintenance actions". The manufacturer advised that they previously supplied the Rego 8180 valve, but now supplied the BMV 344 handwheel-type liquid offtake valve in place of the Rego 8180 valve. The BMV valve was similar to the Rego 8180 valve. Balloon industry personnel suggested that while the Rego 8180 valve was the most widely used fitting, the Rego 8101P5/7141M combination was also relatively widely used in ballooning applications.

While the balloon manufacturer's documentation provided guidance regarding selection of fuel cylinder fittings, general practice among balloonists was for gas supply companies to replace, if required, fuel cylinder fittings during the mandatory 10-yearly cylinder inspection. Gas supply company personnel generally have extensive experience and knowledge regarding fuel cylinder maintenance, but they do not normally have much involvement in the aviation industry. They are not provided with detailed guidance regarding the appropriate selection and configuration for fuel cylinder fittings for aviation applications.

The investigation did not establish who had installed the Rego 8101P5/7141M combination liquid offtake valve.

The pilot of a piper Archer was cleared for final by the Terminal Area (TMA) controller for a practice runway 35 Instrument Landing System (ILS) approach at Canberra. The duty runways at Canberra were 17 and 12. A Saab 340, VH-KDQ, had recently departed from Canberra using runway 17 when the Canberra surface movement controller (SMC) recognised that it was tracking in the opposite direction towards the Archer which was on final approach. The TMA controller took action to resolve the situation by instructing the pilot of the Archer to turn away from the ILS approach. The Archer was at about 8 NM on final approach at 4,500ft while KDQ was 2 NM upwind leaving 3,000ft on climb. The Canberra aerodrome controller (ADC) dept KDQ on frequency until he observed on radar that the Arhcer was turning and then instructed the crew of KDQ to contact the TMA controller.

The separation standard required between aircraft was either 3 NM laterally or 1,000ft vertically. Examination of recorded radar data indicated that the distance between the aircraft was about 4 NM laterally and 1,100ft vertically at the closest point of approach. There was no infringement of separation standards.

The TMA controller had moved the electronic flight strip for the Archer into the traffic management window of The Australian Advanced Air Traffic System (TAAATS) display, indicating that the aircraft was to carry out the ILS approach. The movement of the electronic strip into the traffic management window automatically indicated the pending arrival of the aircraft to the ADC in Canberra Tower. The ADC annotated the electronic strip with a "back-slash", which indicated an acknowledgment of the pending transfer.

Six aircraft had been issued airways clearances for departure from Canberra. The TMA controller was aware of the pending departures but he was not aware of when they would be ready for take-off. Two of those aircraft, Impulse 935 and VH-KJQ, subsequently taxied and the ADC advised the TMA controller that he was releasing those aircraft. Auto release procedures, which were in operation at the time, authorised the ADC to clear aircraft for take-off on pre-determined departure tracks after advising the TMA controller of the pending release. Auto release procedures were designed to minimise voice coordination between the TMA controller and ADC. Under auto release procedures, dependence was placed on the ADC to ensure that there was sufficient spacing between successive departing aircraft to enable the TMA controller to establish and maintain the required separation standard. The ADC advised the TMA controller that the Archer could "have the ILS" after those two aircraft, while also reiterating that there were a number of additional pending departures.

By the time KJQ had become airborne, a further three aircraft had taxied for departure: Eastern 832, Impulse 917 and KDQ. The ADC advised the TMA controller that two of the aircraft were approaching the holding point and one was just leaving the parking apron. The ADC also instructed the TMA controller to "hold [the Archer] out". The TMA controller did not acknowledge that instruction nor did the ADC seek acknowledgment. The ADC subsequently advised the TMA controller that he was releasing "Eastern 832 followed by Impulse 917 then KDQ". The TMA controller replied "Roger".

The TMA controller was required to annotate his electronic flight strip with an "A" for each aircraft to signify that auto-release coordination had been carried out. After receiving the coordination on the latter three aircraft, the TMA controller did not immediately annotate his electronic strips. Rather he advised the pilot of the Archer of a further delay and provided radar vectors for re-sequencing. When he did annotate the electronic strips with an "A", he only annotated Eastern 832 and Impulse 917. The controller stated later that he might have omitted to annotate the electronic strip for KDQ by confusing that aircraft with KJQ, the crew of which had just called the controller with a departure report.

The TMA controller then vectored the Archer to carry out the ILS approach after the departure of Impulse 917. After that crew had contacted the TMA controller, the pilot of the Archer was cleared for final for the ILS approach. By the time KDQ became airborne, a further two aircraft had taxied and the ADC coordinated their release with the TMA controller. The TMA controller queried that they would be "after" the Archer, to which the ADC replied "no they're RPT [Regular Public Transport] they've got higher priority they are going".

The ADC and TMA controllers then entered into a discussion about the situation that lasted about 26 seconds. During that period neither controller seemed to understand where the aircraft under the other person's control was in relation to the aircraft under their control. It was not until a third party, the Canberra SMC, intervened that the controllers understood there was a potential conflict situation and the TMA controller then took action to resolve the situation.

Auto-release procedures

Canberra Local Instructions stated that prior to issuing a take-off clearance, the ADC "shall advise the TMA controller of the pending release and receive an acknowledgment by callsign". During this occurrence, the ADC released five aircraft: none were acknowledged by callsign nor were callsign acknowledgments sought.

Voice coordination - arriving aircraft

Movement of the electronic flight strip into the traffic management window and acknowledgment of the sequence by annotating the strip with a backslash was normally the only coordination required between the TMA and the ADC for an arriving aircraft. Canberra Local Instructions stated that, in addition to the use of the traffic management strip, the TMA controller "shall voice coordinate when:

a) An instrument approach other than a straight-in approach to the system arrival runway will be conducted."

Further, Canberra Local Instructions stated that use of the reciprocal runway directions may be approved for individual aircraft:

"a) when an aircraft is conducting a practice instrument approach and missed approach subject to mutual agreement between TMA and CBA [ADC]".

From the time the Archer was turned away from the ILS approach on the first occasion there was no mutual agreement between the controllers for the use of the reciprocal runway and there was no voice coordination regarding the subsequent approach for the aircraft.

Traffic Management

The Archer pilot contacted the Melbourne Senior Terminal Area Controller (STAC) to book a training ILS approach at Canberra. The booking system established an order of priority for flight crews competing for training ILS approaches. It was reported that it would be unusual for the STAC to deny an ILS booking. It was mainly a paperwork exercise and there were no known busy times blocked out on the booking sheet. In this particular instance there was no coordination between the FMA staff and Canberra tower staff regarding the suitability of the timing of the training ILS approach for the Archer, despite seven pending departures from the reciprocal runway around the same time.

Organisational Issues

The Canberra TMA controllers were originally co-located with the aerodrome function in Canberra. During that time controllers were rotated through both TMA and aerodrome elements. In 1994, the TMA element was relocated to Melbourne. The controllers involved in this occurrence had 5.5 and 7 years experience respectively in their positions at Canberra Tower and in Melbourne. During that time, both had two familiarisation visits to each other's unit. In both cases, one visit was prior to the transition to TAAATS and one was as part of the transition process. Neither controller believed that the frequency of these visits was sufficient to maintain an appropriate level of awareness and appreciation of the other person's working environment.