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On 15 April 2016, an instructor and student of a Grob G115C2 aircraft, registered VH-ZTA (ZTA), were conducting a local training flight in the training area south of Jandakot Airport, Western Australia. Two aerodromes were situated in the training area – Serpentine and Murray Field, and they shared a common traffic advisory frequency (CTAF).

When ZTA was north-west of Serpentine aerodrome and tracking south, the instructor broadcast that they were 10 NM from Serpentine at 2,500 ft and intended to pass abeam the aerodrome tracking south.

At about that time, a Morgan Cheetah aircraft, registered 19-5456 (5456), departed Serpentine for a private flight to Rottnest Island with a pilot and one passenger on board. The pilot reported that they made the following broadcasts on the CTAF: taxiing at Serpentine for runway 23; entering and rolling on runway 23 for a departure to Rottnest Island; and when departing overhead the aerodrome at 1,500 ft climbing to 3,000 ft heading to Rottnest via Carnac.

The pilot then changed the aircraft’s only VHF radio from the CTAF to the area frequency about 5 NM from Serpentine. The aircraft was then climbing through about 2,800 ft and tracking north-west when the pilot sighted an aircraft (ZTA) about 10–15 ft above, on a reciprocal track and about 100 m away. The pilot of 5456 immediately turned left and descended.  

The student of ZTA sighted an aircraft (5456) in close proximity and alerted the instructor. The instructor saw 5456 making a steep left turn at about the same height as ZTA, took control of the aircraft from the student, and conducted a left turn to increase separation between the two aircraft. The aircraft passed at the same level and about 20 to 30 m horizontally from each other.

A search for other traffic is eight times more effective when a radio is used in combination with a visual lookout than when no radio is used. In areas outside controlled airspace, it is the pilot’s responsibility to maintain separation with other aircraft. For this, it is important that pilots use both alerted and un-alerted see-and-avoid principles.


Aviation Short Investigations Bulletin - Issue 51

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General details
Date: 15 April 2016 Investigation status: Completed 
Time: 10:00 WST  
Location   (show map):Serpentine (ALA), 15 km NW Investigation type: Occurrence Investigation 
State: Western Australia Occurrence type: Near collision 
Release date: 08 September 2016 Occurrence class: Operational 
Report status: Final Occurrence category: Serious Incident 
 Highest injury level: None 
Aircraft 1 details
Aircraft manufacturer: Grob - Burkhart Flugzeugbau 
Aircraft model: G-115C2 
Aircraft registration: VH-ZTA 
Serial number: 82048/C2 
Type of operation: Flying Training 
Sector: Piston 
Damage to aircraft: Nil 
Departure point:Jandakot, WA
Destination:Jandakot, WA
Aircraft 2 details
Aircraft manufacturer: Morgan Aero Works 
Aircraft model: Cheetah 
Aircraft registration: 19-5456 
Serial number: Unknown 
Type of operation: Private 
Sector: Piston 
Damage to aircraft: Nil 
Departure point:Serpentine, WA
Destination:Rottnest, WA
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Last update 18 April 2017