Aviation safety investigations & reports

Loss of separation involving Boeing 737, VH-VZC and Boeing 737, VH-VOT at BLAKA

Investigation number:
AO-2011-090
Status: Completed
Investigation completed

Summary

Download Final report
[Download  PDF: 1.53MB]
 

What happened

On 29 July 2011, at 0756 Eastern Standard Time, a loss of separation occurred between a Boeing Company 737-838 aircraft, registered VH-VZC (VZC), and a Boeing Company 737-8FE aircraft, registered VH-VOT (VOT), in the holding pattern at BLAKA, an IFR reporting point south-west of Brisbane, Queensland. The aircraft were inbound to Brisbane on the same air route, with a requirement to hold at BLAKA for sequencing.

The air traffic controller, who had been recently endorsed on the control position, did not identify that the sequence in which the two aircraft entered the holding pattern had changed, and twice assigned VOT descent through the flight level of VZC. The flight crew of VZC identified the confliction and queried the controller, who then took action to recover the compromised separation situation. Separation reduced to 3.9 NM (7.2 km) and 400 ft. The required separation standard was either 5 NM (9.3 km) or 1,000 ft.

What the ATSB found

The Australian Transport Safety Bureau (ATSB) identified that the controller received a reduced amount of on-the-job training, was allocated multiple training officers, and was required to intermittently staff another control position during and immediately following their training on the Gold Coast en route sector. As a result, the controller probably had not consolidated effective control techniques for the sector, particularly for high workload situations.

The ATSB also found that, even though the quality of the controller’s training had been affected by several factors, the controller’s planned on-the-job training period had been reduced from 6 weeks to 4 weeks. More importantly, there was no requirement for a systematic risk assessment to be conducted and documented when the planned amount of training for a controller was reduced.

What has been done to fix it

Airservices Australia advised that it would develop a training variation form to systematically assess risk associated with amendments to the planned length of controller training programs, and completion of the form required the involvement of the controller’s line manager and the Operational Training Manager. Airservices also indicated several other proposed enhancements to its controller training.  

Safety message

In order for the training of operational personnel to be managed safely and effectively, organisations should have a structured risk assessment process in place to evaluate proposed changes to a training program.

Download Final report
[Download  PDF: 1.53MB]
 
 
 
General details
Date: 29 July 2011   Investigation status: Completed  
Time: 07:56 EST    
Location   (show map): 93 km south-south-east of Brisbane Airport   Investigation type: Occurrence Investigation  
State: Queensland   Occurrence type: Loss of separation  
Release date: 06 March 2013   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-VZC  
Serial number 34197  
Operator Qantas  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Melbourne, Vic  
Destination Brisbane, Qld  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-VOT  
Serial number 33801  
Operator Virgin Australia  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Melbourne, Vic  
Destination Brisbane, Qld  
Last update 14 November 2018