| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. Because occurrence briefs are not investigations under the Transport Safety Investigation Act 2003, the information in them is de-identified. |
What happened
On 1 December 2024, a Jonker Sailplanes JS3 glider was participating in a gliding competition at Lake Keepit in central New South Wales. About 1504 local time, the glider was 18.5 km west‑north-west of Lake Keepit and tracking north at about 5,500 ft above mean sea level, in uncontrolled airspace (Class G) when the pilot became aware of motion in their right-hand peripheral vision. On closer inspection, the pilot visually identified a larger aircraft, later reported as a Cessna 208B EX (Caravan). The Caravan was on descent to Gunnedah Aerodrome, in a south-westerly direction on a directly converging course and passing through about the same altitude. The glider climbed as the Caravan manoeuvred to the left and descended to pass behind the glider. Both aircraft passed about 100 to 200 m apart, with little vertical separation however, avoided collision (Figure 1).
Figure 1: Representation of aircraft flight paths before near-collision occurrence
Source: Google Earth, Flight radar 24 and annotated by the ATSB
The Caravan was one of two Caravans from the same company travelling to Gunnedah, from the Gold Coast, Queensland, under instrument flight rules (IFR). Both Caravans had observed other gliders on their descent to Gunnedah Aerodrome but reported not being able to contact them on the Gunnedah common traffic advisory frequency (CTAF)[1] and that they were not displayed on the ADS-B (automatic dependent surveillance-broadcast) traffic display of their navigation system.
Although not mandated for use in class G airspace the glider was equipped with flight alarm (FLARM), but not ADS-B, and therefore did not broadcast its position in a format that would appear on the Caravans’ traffic display. FLARM is an EASA[2]-approved electronic system used to selectively alert pilots to potential collisions between aircraft. It is not formally an implementation of ADS-B, as it is optimised for the specific needs of light aircraft, not for long-range communication or ATC interaction. Australian FLARM algorithms are optimised for collision avoidance for gliders.
The glider reported being on the competition safety frequency and monitoring the Lake Keepit CTAF. Both aircraft continued their respective journeys without further incident.
On return to the Gold Coast, the pilot of the Caravan involved in the near collision, debriefed with the company chief pilot and discovered that a NOTAM[3] advising of the gliding competition had been overlooked in their pre-flight planning.
Safety message
The summer months see a significant increase in recreational aircraft activity and Australia-wide gliding competitions attract large numbers of participants. Gliding Australia issues Gliding Activity Advisory notices to industry each month. Advance notice of such events or any other potential airspace hazards reduces the risk of incidents. Accessing and reviewing NOTAMs is an integral part of flight planning and plays a key role to help improve safety in the skies for all aviators. Pilots should allocate an appropriate time for reading NOTAMs during flight planning as they contain critical safety information that may impact more than just pre-flight preparation. More information on NOTAM conventions can be found on the Airservices website.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report and allow for greater industry awareness of potential safety issues and possible safety actions.
[1] Common Traffic Advisory Frequency (CTAF) is a radio frequency pilots use to communicate with each other when a control tower is not available. Pilots can share their position, altitude, and intentions with other aircraft in the area.
[2] European Union Aviation Safety Agency (EASA) has responsibility for civil aviation safety in Europe.
[3] Notice to Airmen (NOTAM) is a notice filed with an aviation authority to alert pilots of potential hazards along a flight route or at a location that could affect the flight.