Four high-capacity air transport passenger aircraft were en route to Perth under the control of the Melbourne Sector 1 controller, using procedural control methods. Two aircraft were on air route L513 and the other two aircraft were on air route Q76/J68. The routes converged and aircraft at the same level or not longitudinally separated would be in lateral conflict at the Perth 150 NM position for the routes. The aircraft were occupying FL270, FL280 and FL290. Aircraft on the same routes were separated by the minimum vertical separation standard of 1,000 ft.

However, the aircraft's estimates for the 150 NM Perth positions were within an eight minute period which did not provide a longitudinal separation standard. The controller elected to descend VH-TAX, a Boeing 737, which was at FL280 on route Q76/J68 to FL260 prior to the 150 NM position, to maintain separation with an aircraft at the same level on route L513. The crew descended to FL260 as instructed. Subsequently, the sector 1 controller was queried by another controller as to the separation standard used to maintain separation with VH-HYJ, an Airbus A320, which was on route Q76/J68 at FL270. The controller had descended TAX through the level of HYJ without an appropriate longitudinal standard being applied between the aircraft. There was a breakdown of separation.

The lack of a longitudinal standard between TAX and HYJ had been recognised by the previous sector controller. This controller had annotated the flight progress strips for HYJ to provide a prompt for distance checks. The sector 1 controller was nearing the end of his shift, during which he had worked the last three hours alone. To accommodate training commitments for other controllers and for his own purposes the controller's shifts had been swapped on a number of occasions. The number of recent shifts worked, the time of day and the fact that the controller was nearing the end of his shift probably combined to provide an environment in which he became less vigilant in the scanning of the flight progress strips. Consequently, he did not appreciate that there was not a longitudinal separation standard between the aircraft.

The wind at the time was reported to be from the south-east at 15 to 20 kt with gusts to 25 kts. The pilot had flown away from a mob of cattle at 50 kts in a south-westerly direction across the wind, to check on some other animals. He then reduced speed and turned left into wind at a height of about 15 ft above ground level. As he was rolling out of the turn, the helicopter sank to the ground. The helicopter cartwheeled forward and came to rest inverted. The aircraft was within weight and balance limits for the flight and was reported to have been operating normally before the accident. The pilot reported having flown 6.4 hours that day.

The take-off was rejected at speed of approximately 30 kts due to EICAS message 'L ENG BLEED'. The operator advised that the right pack flow control shut-off valve was replaced due to suspected faulty electrical connector. Subsequent leak and BITE checks confirmed normal operation.

During the flight from Sydney to Coolangatta the aircraft encountered unexpected turbulence. The Purser, who was on the flight deck at the time, returned to the cabin, fastened her seat belt, and made an announcement for passengers to secure their seat belts. The pilot reported that the turbulence was unforecast and occurred in clear conditions, lasting for about two minutes. A child, who was in a rear toilet at the time, was injured. The child described being unable to brace herself against the force of the turbulence and being thrown about the toilet, hitting her head on a tap. She suffered soft tissue injuries, bruising around the lower left rib area and concussion. 

he seat belt sign was not on when the child entered the toilet, but had been turned on at the onset of the turbulence. Two cabin crew, who were in the rear galley at the time, reported that the turbulence was so sudden and severe, that they were unable to take their seats. They braced themselves against the galley and a rear exit door. At that time the child opened the toilet door, and one of the flight attendants, believing it was safer for the child to remain in the toilet, told her to go back in and hold on to the rail. The flight attendant managed to get to his seat and fasten his seat belt. When the turbulence subsided he took the child to her mother.

Despite developments in technology and procedures designed to detect and avoid clear air turbulence, aircraft continue to encounter hazardous conditions resulting in injuries. Following a number of recent severe injuries and a passenger fatality due to the effects of in-flight turbulence, the international airline industry is increasing its efforts to educate passengers as to the seriousness of the problem. Methods to protect passengers and crew when turbulence events occur are also being examined.

SAFETY ACTION

As an outcome from a recent turbulence incident in which passengers and crew were injured during a flight from Japan to Sydney, the operator now requires passengers to have their seat belts fastened while seated.

The slat asymmetry warning message illuminated as the crew were configuring the aircraft to land. The approach was discontinued, and the aircraft was then cleared to 1500 ft to carry out the appropriate safety checks. A decision was taken to divert to Brisbane, where engineering assistance was available. The flight landed at Brisbane without further incident. The aircraft was able to depart for the intended destination a short time later after ground checks determined the original slat asymmetry warning to be spurious.

The crew of VH-KEQ contacted Melbourne Centre at their descent point, 30 NM south of Wagga Wagga and were advised that there was no IFR traffic. The crew completed their pre-descent checklist, briefed for a runway 05 VOR/DME approach and commenced to descend. At 28 NM Wagga and descending through 8,000 ft, the crew broadcast their position on the Wagga MBZ frequency. They received a response from the Wagga Aerodrome Frequency Response Unit, that indicated the frequency had not been used within the preceding five minutes.

The crew of KEQ continued their descent and contacted Melbourne Centre at 18 NM and advised they were transferring to the Wagga MBZ. The crew joined the 05 VOR/DME approach on the 10 DME arc and reported their intentions to Melbourne Centre, nominating a time for an operations normal call. Following this transmission, the crew of a second aircraft VH-EKH, broadcast their position 7 NM south west of Wagga, approaching 3,000 ft. They reported having conducted an overshoot from the runway 23 VOR/DME approach and requested that KEQ climb to 4,000 ft to facilitate separation. Both aircraft subsequently landed safely from the runway 05 VOR/DME approach.

At the time of the occurrence, the ATS Sector 2 and 8 positions were combined. The two crews' initial estimates for Wagga Wagga differed by 8 minutes and the controller's expectation was that the first SAAB would have already landed by the time the second SAAB transferred to the MBZ. The controller is reported to have recognised the conflict between the aircraft and had passed traffic information to the crew of EKH as they initiated a missed approach from the runway 23 VOR/DME procedure. Communication between the two crews was subsequently established on the area VHF frequency with EKH at 7 DME on the overshoot from runway 23 and KEQ on the 10 DME arc and inbound for runway 05. The controller did not pass traffic information to the crew of KEQ.

Following this occurrence, ATS team leaders briefed controllers on the importance of anticipating aircraft separation when issuing traffic information.

The flight was part of a private holiday tour with four adults and two children in the aircraft. The pilot was conducting an approach to land at a property airstrip. There was a headwind of about 20 kts on final approach and he was maintaining an airspeed of 80 kts. When the aircraft descended below the tree line just before landing it entered an area of windshear. The pilot noted an increase in speed at this time and said that the aircraft bounced a number of times after the initial touchdown.

He then elected to go around, applied full engine power, and retracted the flaps from 30 to 20 degrees. He then became concerned about clearing trees to the left of the strip as the aircraft had veered left during the go-around. The aircraft subsequently collided with the trees and impacted the ground heavily. The pilot and one passenger sustained minor injuries. There was no reported problem with the engine or the aircraft during the go-around. Post-accident examination of the aircraft indicated that, at impact, the flaps were in the process of retracting, and the landing gear was down.

Shortly after take-off, the pilot advised ATS that aircraft operation was abnormal and he was returning to Port Lincoln. The pilot requested emergency services be placed on standby as the aircraft had a hydraulic problem and he was unable to extend the landing gear normally. After successfully carrying out a manual extension of the landing gear the aircraft was landed safely. A maintenance investigation revealed a cracked flared fitting in the hydraulic system, which allowed the system fluid contents to be lost. The fitting was changed and the aircraft returned to service. The fitting is the subject of a Defect Report to CASA.

The Departures North controller was controlling a Beechcraft Super Kingair B200C, radio callsign Alpha-Mike-Mike, and a British Aerospace BAe146 radio callsign Echo-Whiskey-Mike. Both aircraft had departed Sydney to the south-east. The crew of the Kingair were flying a radar departure, on a heading of 120 degrees, maintaining 5,000 ft. The crew of the BAe146 were flying a runway 16L COOKS ONE standard instrument departure (SID).

The Departures North controller confused the callsigns of the two aircraft and, although intending to turn the B200C, mistakenly instructed the crew of the BAe146 to turn left onto a heading of 350 degrees. The BAe146 was then cleared to leave 5,000 ft on climb to flight level 240. The combination of both instructions placed the BAe146 in the Approach South/Director controller's airspace and in potential conflict with a Boeing B737 on left downwind for runway 25 that had been assigned descent to 5,000 ft.

Both the Approach South controller and the Departures North controller recognised that the aircraft were in conflict as soon as the BAe146 started to turn onto the assigned heading and issued remedial instructions to both crews.

The required separation standard was either 1,000 ft vertically or 3 NM horizontally. Analysis of the radar data indicates that the B737 did not descend below 5,500 ft and that the BAe146 did not climb above 4,600 ft. The vertical difference of 900 ft occurred while the aircraft were less than 3NM apart and there was consequently an infringement of the separation standards.

The crew of the BAe146 sighted the B737 and were able to maintain visual separation.

The investigation revealed that the Departures North controller had worked six extra shifts on overtime or emergency duty in the previous 7 weeks, including an overtime shift the previous day. Fatigue was considered to be a contributory factor.

LOCAL SAFETY ACTION

Air Traffic Control Management at Sydney made two recommendations as a result of this incident:

"Recommendation 1. That strategies be put in place to limit the amount of overtime or extra duties worked by terminal control unit (TCU) staff. Should the present measures be withdrawn, other measures will be necessary".

"Recommendation 2. That the mode of operation, 16 Departures/25 Arrivals, be reviewed so as to permit two outbound radials to the north for different performance aircraft".

BASI SAFETY ACTION

As a result of this investigation and a number of similar occurrences, the Bureau of Air Safety Investigation conducted an investigation of systemic issues at the Sydney terminal control unit and issued report B98/90 on 18 August 1998. Nine recommendations were made in the report. The following two recommendations are considered relevant to this investigation.

R980159

The Bureau of Air Safety Investigation recommends that Airservices Australia reassess the human factor hazard analysis for both Stage One and Stage Two of the long-term operating plan (LTOP) safety cases so that the mitigating strategies applied to identified hazards adequately allow for the fundamental limitations of human performance. In reassessing this hazard analysis, BASI recommends that Airservices Australia seek the assistance of human performance expertise.

R980160

The Bureau of Air Safety Investigation recommends that Airservices Australia consider restructuring the current roster operating in the Sydney TCU to ensure that contemporary fatigue management research is translated into meaningful duty hour regulations. In any restructure of the roster, BASI recommends that Airservices Australia expand its absentee management program to include individuals who expose themselves to the risks of fatigue by participating in excessive amounts of overtime and/or emergency duty.

The aerodrome controller (ADC) at Perth tower had cleared the Boeing 737 to line up on runway 21. An Airservices Australia car was accompanying the airfield mower cutting grass at the runway's edge, approximately midway along the runway. The ADC was aware that the car was just within the flight strip but he was not aware of the existence of the mower. Only after he cleared the 737 to take off and it had begun rolling, did he become aware of the mower and its close proximity to the runway. He instructed the pilot of the 737 to cancel the take-off.

The surface movement controller (SMC), who had not heard the take-off clearance, became aware of impending confliction when the aircraft began rolling. He instructed the car to vacate the flight strip. The aircraft stopped approximately 600 m before the original position of the mower having rolled approximately 750 m. The mower was a small blue vehicle and was approximately 1500 m from the tower and would have been difficult to see from the tower. The ADC had taken over the position approximately 10 minutes prior to the incident. He reported that he could not recall being advised about the mower during the handover so the ADC was unaware of the mower's existence.

However, the "runway occupied" strip had been placed in the ADC's departure runway designator console but because the ADC did not post the aircraft's flight strip on the console before clearing the aircraft for take-off, he did not note that the mower's operation near runway. The manual of air traffic services (MATS) details a requirement that an aircraft not be issued with a take-off clearance until its flight strip has been placed under the "runway occupied" strip at the ADC console and the runway has been vacated. When the ADC issued the take-off clearance, he had assumed that the SMC had ensured that the runway was vacated although he had not coordinated with the SMC to ensure that such was the case.

The tower coordinator normally supervised the operations within the tower but he was pre-occupied at the time recording information for the automatic terminal information service (ATIS). He had, therefore, not noticed the incident developing until the aircraft had begun its take-off run. He reported that he then called to the ADC to stop the aircraft because there was a vehicle on the runway.

LOCAL SAFETY ACTION

Airservices Australia has issued a local instruction highlighting the necessity of full handover procedures and a requirement to address escort vehicles with their callsign and escorted company on all radio communications and during tower coordination.