Jump to Content
Download Final Report
[ Download PDF: 290KB]

On 12 March 2014, at about 1211 Central Standard Time, the crew of a United States military Boeing 737 aircraft, call sign ‘Convoy 7186’, requested a clearance from the air traffic control (ATC) planner at Darwin Airport, Northern Territory, for a flight to Kadena Air Base, Japan via the ‘A461’ air route.

The planner cleared Convoy 7186 to track to the destination via the ‘OCTOB’ waypoint at 5,000 ft above mean sea level (AMSL) and for an ‘OCTOB TWO’ standard instrument departure (SID).

At about 1245, the tower controller cleared the pilot of a Cessna 206 aircraft, registered VH-RAP (RAP), for take-off from runway 29 at Darwin, then to turn right onto a heading of 320° and climb to 3,000 ft AMSL.

The crew of Convoy 7186 then contacted the tower approaching the holding point for runway 29 and requested an ‘IFR release’. The tower controller asked the crew to repeat the call. The crew stated that they wanted to verify they were ‘direct OCTOB on the go, up to 5,000’. The tower controller replied ‘Affirm’.

At about 1248, the approach controller identified RAP and requested the pilot to maintain 2,000 ft to guarantee separation assurance with the following aircraft. Shortly after, the crew of Convoy 7186 contacted the approach controller and advised they were passing 2,000 ft on climb to 5,000 ft and tracking direct to OCTOB.

The approach controller immediately issued a safety alert and advised the crew that there was a VFR aircraft at 2,000 ft about 1 NM ahead and that Convoy 7186 was cleared on an OCTOB TWO departure. The crew replied, ‘Negative, it’s direct to OCTOB on the go’ and advised that they had the VFR aircraft in sight.

This incident highlights the importance of using standard phraseology in all radio communications.


Aviation Short Investigations Bulletin - Issue 32

Download Final Report
[ Download PDF: 290KB]
General details
Date: 12 March 2014 Investigation status: Completed 
Time: 1250 CST  
Location   (show map):Darwin Airport Investigation type: Occurrence Investigation 
State: Northern Territory Occurrence type: Loss of separation 
Release date: 14 July 2014 Occurrence class: Airspace 
Report status: Final Occurrence category: Serious Incident 
 Highest injury level: None 
Aircraft 1 details
Aircraft manufacturer: The Boeing Company 
Aircraft model: 737 
Type of operation: Military 
Sector: Jet 
Damage to aircraft: Nil 
Departure point:Darwin, NT
Aircraft 2 details
Aircraft manufacturer: Cessna Aircraft Company 
Aircraft model: 206 
Aircraft registration: VH-RAP 
Serial number: U20602989 
Type of operation: Charter 
Sector: Piston 
Damage to aircraft: Nil 
Departure point:Darwin, NT
Share this page Provide feedback on this investigation
Last update 14 November 2018