The pilot of a Piper Chieftain had planned an instrument flight rules (IFR) flight from Taree to Sydney via overhead Williamtown. After the aircraft became airborne, the pilot contacted the Myall sector controller. The controller told the pilot there was no other IFR traffic and that the Williamtown restricted areas were active. Shortly after, the controller told the pilot that clearance on the planned track was not available and to remain clear of the Williamtown restricted areas. The pilot was told to expect clearance via the Williamtown - NICLA track. However, the controller had intended to tell the Chieftain pilot to expect a clearance via the Taree - NICLA track. The track from Taree to NICLA is 237 degrees. The pilot did not query the controller regarding the amended route. He acknowledged the controller's transmission and then reported intercepting the 198 degree track from the Taree NDB navigation aid direct to Williamtown, on climb to 8,000 ft. The controller subsequently saw on his radar display that the Chieftain was 15 NM south of Taree at 5,000 ft, inside the Williamtown restricted area. The Chieftain was also approximately 3 NM to the north of a northbound IFR de Havilland Dash 8 that was on descent to Taree. The aircraft subsequently passed each other safely.
Pilots of aircraft on the ground at Taree can normally communicate via VHF radio with the Myall sector, which is located in the Brisbane air traffic control centre. The Chieftain pilot later reported that he had attempted, unsuccessfully, to contact the controller on the aircraft's VHF radio while taxiing. The investigation could not establish why the Chieftain pilot was unable to communicate with the controller. The Chieftain was not fitted with a high frequency radio.
When the pilot of a southbound flight reports taxiing at Taree, controllers normally issue a secondary surveillance radar (SSR) code and then coordinate a clearance for the flight with Williamtown air traffic control. A controller can then issue a clearance once the aircraft is identified on radar after departure. As communication was not established until the Chieftain was airborne the controller had to coordinate with Williamtown after the pilot reported departure.
Because radar coverage in the Taree area was not available below about 4,500 ft, controllers were required to pass traffic information to IFR aircraft on other IFR aircraft. The Dash 8 and the Chieftain flights were traffic for each other. The controller later reported that he expected to identify the Chieftain before the Dash 8 left the Williamtown restricted area. Also, he considered that the amended track for the Chieftain would have provided separation, as it diverged from the inbound track of the Dash 8. After the Chieftain pilot's departure report, the controller did not appreciate that the aircraft was tracking direct to Williamtown and was likely to conflict with the Dash 8 on the reciprocal track.
The preferred route between Taree and Sydney, as listed in the Aeronautical Information Publication en route supplement, was W238 to NICLA and Craven, a position 41 NM west-south-west of Taree. That route avoided the Williamtown restricted area. The Chieftain pilot was unfamiliar with waypoint NICLA and was attempting to locate its position on his chart as the aircraft climbed.
During the departure the Chieftain pilot made radio broadcasts in accordance with common traffic advisory frequency (CTAF) procedures. The CTAF is used for operations in non-controlled airspace and is not monitored by air traffic control. Immediately after departure, the pilot broadcast on the CTAF that the aircraft was tracking to the Mount Mcquoid VOR navigation aid, located 39 NM south-west of Williamtown. He also advised that the aircraft was on climb to 8,000 ft. Shortly after, he contacted the Dash 8 pilot in response to the latter's inbound CTAF broadcast. The Dash 8 pilot was advised by the Chieftain pilot that he was 6 NM south of Taree passing 4,100 ft and tracking direct to Williamtown. The Dash 8 pilot then queried the controller regarding the Chieftain's position. The controller confirmed the position of the Chieftain relative to the Dash 8. The Dash 8 pilot then returned to the CTAF and advised sighting the Chieftain. The Chieftain pilot reported to the Dash 8 pilot that he could see the Dash 8.
The Dash 8 pilot later reported that he had used controller and CTAF reports plus information from his aircraft's traffic alert and collision avoidance system (TCAS) to see the Chieftain. He estimated the aircraft passed with about 3 NM lateral displacement.
Both pilots reported that the controller's frequency was very busy with a lot of radio transmissions.
The controller assumed that adequate separation would be achieved based on his experience. However, that left little margin to recover the situation after he saw the Chieftain on radar, tracking to Williamtown. The provision of traffic information would have probably enabled the Chieftain pilot to take action earlier to avoid the Dash 8.
The Chieftain pilot did not flight plan via the recommended track for aircraft operating from Taree to Sydney. Had he planned via NICLA it is unlikely that he would have entered the restricted area without a clearance. It would have also minimised the possibility of conflict with aircraft on the Williamtown - Taree track, which was one of the intentions of the preferred track advice in the en route supplement. The non-use of the preferred track to Sydney and the pilot's unfamiliarity with waypoint NICLA were indicators of inadequate flight preparation.
The Chieftain pilot had little option but to depart Taree when he was unable to communicate with the controller. However, that meant the pilot would be busy with CTAF broadcasts and establishing contact with the controller during the initial stages of the flight. It is likely that the increased workload, and the need for him to find NICLA, caused the pilot to probably approach task saturation. That was indicated by the pilot not appreciating the illogical aspects of being advised, in the same radio transmission, to expect a clearance by the Williamtown - NICLA track and to avoid the restricted area. Had the pilot been less busy with the flight, or more familiar with the area, he probably would have requested the controller to confirm the track to be adopted.
The controller was also probably approaching task overload as he coordinated a clearance for the Chieftain with Williamtown air traffic control. That was likely the reason for the controller advising the pilot of the incorrect track. In addition, he missed the pilot's advice of tracking direct to Williamtown. Had the controller been less busy he would have probably appreciated the content of both his and the Chieftain pilot's transmissions and taken action to clarify the situation. That could have included either navigation assistance or the provision of traffic information to the pilot.
The proximity of the Taree CTAF to the Williamtown restricted area results in increased complexity for both controllers and pilots, especially when aircraft are operating between controlled and non-controlled airspace. In this occurrence the use of TCAS by the Dash 8 pilot, and adherence to CTAF procedures by both pilots assisted them to resolve the situation. The occurrence also highlighted the importance of effective planning for both controllers and pilots prior to commencing duty or undertaking flights respectively.
1. The Chieftain pilot was unfamiliar with the airspace in the area.
2. The Chieftain pilot did not plan via the preferred route.
3. The Chieftain pilot was not provided with traffic information
on the Dash 8 by air traffic control.
4. The proximity of the Taree CTAF to the Williamtown restricted area increased the complexity for operations in the area.
5. The controller did not appreciate the potential for conflict when the Chieftain pilot reported tracking direct to Williamtown.
6. The use of TCAS by the Dash 8 pilot and adherence to CTAF procedures by both pilots to locate and avoid the other aircraft.
Local safety action
As a result of their investigation of the occurrence Airservices Australia Northern District:
- briefed team leaders to specifically consider the traffic information parameters used by controllers during performance assessments; and
- briefed team leaders when developing rosters to consider the provision of appropriate support and supervision for controllers in busy periods.
|Date:||24 October 2000||Investigation status:||Completed|
|Time:||1935 hours ESuT|
|Location:||19 km SSW Taree, (NDB)|
|State:||New South Wales||Occurrence type:||ANSP info/procedural error|
|Release date:||18 July 2001||Occurrence category:||Incident|
|Report status:||Final||Highest injury level:||None|
Aircraft 1 details
|Aircraft manufacturer||Piper Aircraft Corp|
|Type of operation||Air Transport Low Capacity|
|Damage to aircraft||Nil|
|Departure point||Taree, NSW|
|Departure time||1930 ESuT|
Aircraft 2 details
|Aircraft manufacturer||de Havilland Canada|
|Damage to aircraft||Nil|
|Departure point||Sydney, NSW|