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Final Report

Summary

On 21 February 2016, a Glaser-Dirks DG-800B glider, registered VH-IGC (IGC), departed from Pipers Field aerodrome, New South Wales. The glider pilot planned to track towards Cowra, and to remain outside a 10 NM radius of Orange Airport. Not long after they departed Pipers Field, the pilot selected their radio to a glider frequency 122.9.

At about 1420 Eastern Daylight-saving Time, a Regional Express SAAB 340B aircraft, registered VH-ZLA (ZLA), taxied at Orange Airport, for a scheduled passenger service to Sydney, New South Wales. The flight crew broadcast on the Orange common traffic advisory frequency (CTAF) when taxiing and again when rolling on runway 11. After receiving an initial air traffic control clearance, the captain requested a further clearance to track 5 NM right of track to remain clear of cloud. As the captain read back the amended clearance, the aircraft was climbing through about 7,500 ft. The captain sighted the glider (IGC) ahead, just below the cloud base, and assessed there was a risk of collision. The captain immediately took control of the aircraft from the first officer, disconnected the autopilot and lowered the nose of the aircraft to ensure it passed below the glider. The flight crew estimated that the glider passed within about 100 m of the aircraft.

The glider IGC was descending through about 8,560 ft AMSL, and 11 NM from Orange Airport, when the pilot of IGC sighted ZLA in their 3 o’clock position and climbing towards them. The pilot of IGC assessed that while ZLA was on a direct track towards IGC, due to its climb rate there was no risk of collision, and elected to continue on their current track. The pilot of IGC estimated that ZLA passed about 200 m below the glider.

Pilots are encouraged to ‘err on the side of caution’ when considering when to make broadcasts and whether specific frequencies should be monitored, particularly noting the fundamental importance of communication in the effective application of the principles of see-and-avoid. The ATSB report  Limitations of the See-and-Avoid Principle outlines the major factors that limit the effectiveness of un-alerted see-and-avoid.

 

Aviation Short Investigations Bulletin - Issue 51

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