Aviation safety investigations & reports

Loss of separation involving a Cessna 441, VH-JLT, and a Raytheon B200, VH-ZCJ, near Darwin Airport, NT on 10 June 2015

Investigation number:
Status: Completed
Investigation completed


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On 10 June 2015, a Cessna 441 aircraft, registered VH-JLT (JLT), departed Darwin for a charter flight from Darwin to Oenpelli, Northern Territory with the pilot and 6 passengers on board. The pilot was cleared to depart via the VANDI ONE standard instrument departure (SID).

At about 0856 Central Standard Time, a Raytheon B200 aircraft, registered VH-ZCJ (ZCJ), operating an aeromedical flight with the pilot and four passengers on board, was approaching Darwin from Elcho Island, Northern Territory, on the GATOR THREE A standard arrival route (STAR).

At about 0900, the pilot of JLT contacted the approach controller and advised that they were conducting a VANDI SID, and passing 1,000 ft on climb to 3,000 ft. About 20 seconds later, the pilot of ZCJ reported that they were visual and were then passing about 8,400 ft on descent.

About 30 seconds later, the approach controller cleared JLT to climb to flight level (FL) 130. The controller did not cancel any requirements, hence JLT was still required to be at or below 6,000 ft at waypoint BAXIB in accordance with the SID. Shortly after that communication, the pilot of JLT inadvertently selected Brisbane Centre frequency, and was no longer able to hear Darwin Approach frequency.

At about 0902, ZCJ was approaching waypoint BITES at 7,000 ft, JLT was at 5,000 ft and the aircraft were about 6 NM apart. The controller then issued JLT as traffic to the pilot of ZCJ. As the two aircraft converged, an Australian Defence Air Traffic System (ADATS) predicted conflict alert (PCA) activated on the controller’s situational display. At about 0903, 1.6 NM horizontally and 800 ft vertically existed between the aircraft, and the pilot of ZCJ reported that they had JLT in sight. The pilot of ZCJ then received a TCAS ‘TRAFFIC TRAFFIC’ alert. The approach controller quickly attempted to contact JLT, but did not receive a reply and JLT continued to climb. The controller then advised the pilot of ZCJ that the aircraft had climbed through the 6,000 ft level restriction and issued a requirement to the pilot of ZCJ to maintain separation with that aircraft. By the time the controller had completed that transmission, the two aircraft had passed.

At about 0904, the approach controller received an ADATS conflict alert (CA), with the closest proximity according to the radar reducing to 400 ft vertically and 0.3 NM between the two aircraft. The pilot of JLT sighted ZCJ slightly above, to their left, and closer than normal and realised their radio was selected to Brisbane Centre frequency and switched it to the Darwin Approach frequency. ZCJ landed on runway 11 without further incident.

This incident provides a reminder for pilots to become familiar with published standard departure and arrival procedures and charts, particularly those with intermediate level restrictions, and the associated phraseology.


Aviation Short Investigations Bulletin - Issue 43

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[Download  PDF: 473KB]
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General details
Date: 10 June 2015   Investigation status: Completed  
Time: 0910 CST   Investigation level: Short - click for an explanation of investigation levels  
Location   (show map): near Darwin Airport    
State: Northern Territory   Occurrence type: Loss of separation  
Release date: 07 October 2015   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft 1 details

Aircraft 1 details
Aircraft manufacturer Cessna Aircraft Company  
Aircraft model 441  
Aircraft registration VH-JLT  
Serial number 441-0138  
Type of operation Charter  
Sector Turboprop  
Damage to aircraft Nil  
Departure point Darwin, NT  

Aircraft 2 details

Aircraft 2 details
Aircraft manufacturer Raytheon Aircraft Company  
Aircraft model B200  
Aircraft registration VH-ZCJ  
Serial number BB-1853  
Type of operation Medical Transport  
Sector Turboprop  
Damage to aircraft Nil  
Departure point Elcho Island, NT  
Destination Darwin, NT  
Last update 14 November 2018