Aviation safety investigations & reports

Loss of separation assurance - Boeing 737, VH-VUJ and Boeing 737, VH-VZS, 87 km S Tamworth Airport, NSW, 8 January 2012

Investigation number:
AO-2012-008
Status: Completed
Investigation completed

Summary

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On 8 January 2012, at about 2141 Eastern Daylight-saving time, a loss of separation assurance occurred between a Boeing Company B737-8FE, registered VH-VUJ (VUJ) and a Boeing Company B737-838, registered VH-VZS (VZS), near Tamworth Airport, New South Wales (NSW).
Both aircraft were conducting scheduled passenger services, under the instrument flight rules, with VUJ operating from Sydney, NSW to Brisbane, Queensland and VZS operating from Brisbane to Sydney. Due to weather diversions, the aircraft were operating on reciprocal tracks at the time of the occurrence.

The air traffic controller assigned VUJ climb to the same level maintained by VZS. On activation of the air traffic control system's Short Term Conflict Alert (STCA), when the aircraft were 17.5 NM (32.4 km) and 2,200 ft apart, the controller issued both flight crews instructions that ensured vertical separation was maintained in excess of the required standard and a breakdown of separation avoided.
The controller later reported feeling mentally fatigued following a shift with high complexity and workload. They had not identified the confliction before the STCA, but once aware, the controller's knowledge and application of effective compromised separation recovery techniques was integral in managing the situation.

Following the occurrence, Airservices Australia advised that compromised separation recovery refresher training would be provided to controllers again, in addition to sessions on separation assurance techniques, and that they were implementing a renovated Fatigue Risk Management System and a Normal Operations Safety Survey program.

This incident highlights the need for awareness of the effects of high workload and sustained task complexity on performance, the importance of regular breaks and implementation of strategies, such as the use of conforming levels, when able. In addition, the knowledge and application of effective compromised separation recovery techniques by air traffic controllers is integral in the management of compromised separation situations.

Download Final Report
[Download  PDF: 5.65MB]
 
 
 
General details
Date: 08 January 2012   Investigation status: Completed  
Time: 2140 ESuT    
Location   (show map): 87 km South Tamworth Airport   Investigation type: Occurrence Investigation  
State: New South Wales   Occurrence type: Loss of separation assurance  
Release date: 25 June 2012   Occurrence class: Airspace  
Report status: Final   Occurrence category: Incident  
  Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-VUJ  
Serial number 34443  
Operator Virgin Australia Airlines  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Sydney, NSW  
Destination Brisbane, Qld  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-VZS  
Serial number 39358  
Operator Qantas Airways Limited  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Brisbane, QLD  
Destination Sydney, NSW  
Last update 14 November 2018