Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the Australian Transport Safety Bureau (ATSB) to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation.

On 12 October 2011, the ATSB commenced an investigation into the breakdown of separation, between an Airbus Industrie A320 aircraft registered VH-VGR and a Boeing Company 737 aircraft registered VH-VOD near Melbourne Airport, Vic. Examination of the information collected during the investigation identified that the occurrence had significant similarities to aspects of ongoing investigation AO-2010-104, breakdown of separation, between a Boeing Company 767 aircraft registered VH-OGU and a Boeing Company 737 aircraft registered VH-VBH, near Melbourne Airport, Vic on 5 December 2010.

Accordingly, the ATSB decided to examine the 12 October 2011, breakdown of separation event as part of the broader investigation AO-2010-104 and the separate AO-2011-131 investigation was discontinued.