Another BOS event investigated by the ATSB has been released:
The Australian Transport Safety Bureau (ATSB) established that the controller's mental model for separation correctly identified the situation and included a plan to manage the traffic. However, the instructions that were issued to the pilot of the G-IV contradicted that mental model in that the controller cleared the G-IV for descent through and below the level being maintained by the 737. The progression towards the BOS continued when the controller did not recognise the error during the G-IV pilot's read-back of the clearance.
Ultimately, the controller's earlier correct level input into The Australian Advanced Air Traffic System allowed a system alerting function to activate. In response to that alert, the controller initiated compromised separation recovery actions to recover the required separation standard.
The ATSB identified a number of human factors and individual work processes that contributed to the occurrence. In addition, a safety issue was identified in respect of differences in the traffic alert phraseology between the Manual of Air Traffic Services and Aeronautical Information Publication (AIP). These differences increased the risk of non-standard advice being provided to pilots by controllers during compromised separation recoveries.
In response to this safety issue, Airservices Australia (Airservices) amended the AIP to enhance understanding of the criticality of any safety alerts and avoiding actions being provided to flight crew. This amendment came into effect on 28 June 12.
Investigation: AO-2011-127 - Breakdown of separation - VH-YVA/VH-CGF, 59 km NE Armidale, NSW, 8 October 2011
So ATCers is the above amendment too little, too late? Is there more they could do to lessen the occurrence of these 'BOS' events (other than a frontal lobotomy of the execs)?
Good to see Ben Sandilands is still on the job:
Air traffic officer had mental problem in AU near miss case | Plane Talking