Investigation number
AO-2013-161
Occurrence date
Location
Adelaide Airport, west 19 Km
State
South Australia
Report release date
Report status
Final
Investigation level
Defined
Investigation type
Occurrence Investigation
Investigation status
Completed
Aviation occurrence category
Loss of separation
Occurrence class
Serious Incident
Highest injury level
None

What happened

On 20 September 2013, a loss of separation occurred about 17 km west of Adelaide, South Australia, between an Airbus A330 aircraft, registered VH-EBO (EBO) operating a scheduled passenger service from Sydney, New South Wales to Perth, Western Australia, and an Airbus A330 aircraft, registered VH-EBS (EBS), operating a scheduled passenger service from Perth to Sydney.

Both aircraft were within radar surveillance coverage at the time of the occurrence and were equipped with a traffic collision avoidance system (TCAS).

What the ATSB found

The ATSB determined the en route air traffic controller did not adequately assess the traffic for potential conflicts before issuing a climb instruction to the EBO flight crew. The air traffic control computer system subsequently alerted the controller to the conflict and they promptly commenced compromised separation recovery actions. The flight crew of EBS responded to alerts generated by the aircraft’s TCAS. The TCAS in EBO malfunctioned and did not provide the flight crew with traffic information or generate any safety alerts. The reason for the malfunction could not be determined and the equipment manufacturer considered it to be a unique event.

The ATSB identified a safety issue relating to the convergence of many published air routes overhead Adelaide, combined with the convergence point being positioned on the sector boundary of the Augusta and Tailem Bend sectors, which reduced the separation assurance provided by strategically separated one-way air routes and increased the potential requirement for controller intervention to assure separation.

What's been done as a result

Airservices Australia is undertaking a review of air routes and of the Australian airspace design that contributes to risk. There is also consideration to providing more flexible route structures using modern navigation technology to create traffic directional flows and remove convergence points.

In addition, Airservices undertook pro-active safety action associated with safety alerting and traffic avoidance advice by air traffic services.

Safety message

This occurrence is a reminder of the potential for skill-based errors to occur when experienced personnel are performing their tasks and highlights the importance of controllers following their normal processes to ensure traffic is assessed prior to providing control instructions.

Aircraft Details
Manufacturer
Airbus
Model
A330
Registration
VH-EBO
Aircraft Operator
Qantas
Serial number
1169
Operation type
Air Transport High Capacity
Departure point
Sydney, NSW
Destination
Perth, WA
Damage
Nil
Aircraft Details
Manufacturer
Airbus
Model
A330
Registration
VH-EBS
Aircraft Operator
Qantas
Serial number
1258
Operation type
Air Transport High Capacity
Departure point
Perth, WA
Destination
Sydney, NSW
Damage
Nil