Aviation safety investigations & reports

Loss of separation assurance involving a Boeing 717-200, VH-NXQ and Boeing 777-312ER, 9V-SYI, 303 km N Perth Airport, WA, 25 October 2012

Investigation number:
Status: Discontinued


Two aircraft, both maintaining flight level 350, were on converging tracks with the same estimate for overhead Morawa NDB, Western Australia. A controller noticed the potential conflict and alerted the sector controllers managing the flights, who acted to resolve the situation.  There was a loss of separation assurance. 


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 26 October 2012, the ATSB commenced an investigation into an airspace event involving a Boeing 717-200 aircraft, registered VH-NXQ, and a Boeing 777-312ER aircraft, registered 9V-SYI, near the Morawa non-directional radio beacon, Western Australia, on 25 October 2012.

Examination of the information collected during the investigation indicated that although there was a loss of separation assurance, the potential conflict between the two aircraft was detected and actively managed by air traffic control. This ensured that the required separation standard was maintained.

The ATSB did not find any systemic issues had contributed to the occurrence and assessed that no safety issues would be identified through further investigation. On that basis, the ATSB has decided to discontinue its investigation.

General details
Date: 25 October 2012   Investigation status: Discontinued  
Time: 1403 WST   Investigation level: Systemic - click for an explanation of investigation levels  
Location   (show map): 303 km N Perth Airport, WA (near Morawa NDB)    
State: Western Australia   Occurrence type: Loss of separation assurance  
Release date: 10 July 2013   Occurrence category: Incident  
Report status: Discontinued   Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer The Boeing Company  
Aircraft model 717  
Aircraft registration VH-NXQ  
Serial number 55097  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer The Boeing Company  
Aircraft model 777  
Aircraft registration 9V-SYI  
Serial number 32327  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Last update 03 April 2020