Aviation safety investigations & reports

Loss of separation involving Boeing 737, VH-VUV and Boeing 737, VH-VXM near Ceduna, SA, 8 November 2011

Investigation number:
AO-2011-144
Status: Completed
Investigation completed

Summary

Download Final Report
[Download  PDF: 1.52MB]
 

What happened

On 8 November 2011, a loss of separation occurred between a Boeing Company 737-8FE, registered VH-VUV, and a Boeing Company 737-838, registered VH-VXM, near Ceduna, South Australia. The aircraft were conducting scheduled passenger flights and were under the air traffic control of Airservices Australia (Airservices). The aircraft were operating on converging tracks at 39,000 ft. The procedural longitudinal separation standard of 20 NM (37 km) was infringed. It is likely that there was between 6 NM (11.1 km) and 12 NM (22.2 km) longitudinal separation between the aircraft.

What the ATSB found

The ATSB found that the two controllers involved were experiencing a high workload due to a range of factors, including the number of tasks and their limited experience. Airservices’ processes for monitoring and managing controller workloads did not ensure that newly-endorsed controllers had sufficient skills and techniques to manage the high workload situations to which they were exposed. In addition, Airservices’s fatigue risk management system (FRMS) did not effectively manage the fatigue risk associated with allocating additional duty periods. The ATSB is also concerned that there had been increasing traffic levels and complexity in some sectors in recent years, combined with a decrease in the experience levels of controllers and without a concomitant increase in controller resources. In addition, although Airservices has been in the process of developing and trialling a flight plan conflict function for procedurally-controlled aircraft for several years, the fact that it is still not operational is a safety issue.

What's been done as a result

Airservices reported that the airspace sectors involved in the occurrence had been re-sectorised into three sectors in November 2012 to manage workload and that a working group had been established to determine a suitable workload model to monitor and forecast controller workload on a sector by sector basis. The first stage of a flight plan conflict function had also been deployed in Brisbane Upper Airspace, with further roll out planned in Melbourne Centre in 2014.
In addition, Airservices reported that an updated FRMS had been implemented in July 2012 and that it had addressed the systems limitations outlined in the report.

Safety message

High workload can have significant effects on a controller’s performance. It needs to be monitored and managed using a systemic approach, particularly for less experienced controllers but also those who have recently received a new endorsement. Other recent loss of separation occurrences involving high workloads and newly-endorsed controllers indicate that this problem is not restricted to the sectors involved in this occurrence. Ideally the best way of managing workload is to reduce the level of work demands and distractions. If the work demands cannot be reduced, then another option is to ensure the controllers have the experience, skills techniques and support to effectively manage their task demands.

Download Final Report
[Download  PDF: 1.52MB]
 
 
 
General details
Date: 08 November 2011   Investigation status: Completed  
Location   (show map): near Ceduna Airport   Investigation type: Occurrence Investigation  
State: South Australia   Occurrence type: Loss of separation  
Release date: 18 October 2013   Occurrence class: Airspace  
Report status: Final   Occurrence category: Serious Incident  
  Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-VUV  
Serial number 37821  
Operator Virgin Australia  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Perth, WA  
Destination Brisbane, Qld  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-VXM  
Serial number 33483  
Operator Qantas  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Port Hedland, WA  
Destination Melbourne, Vic.  
Last update 14 November 2018