Separation issue involving a Cessna 404, VH-TTZ and Unknown Glider, 25 km south of Ballarat, Victoria, on 25 February 1995

At the completion of a fire spotting exercise VH-TTZ was passing 9000 feet on descent in controlled airspace (CTA) when a glider was sighted at the same altitude.  Air traffic control had no knowledge of glider operations in the area, for which the lower level of CTA was 6,000 feet. The glider was not identified.

Investigation disclosed that a gliding competition was being conducted from Bacchus Marsh airfield and the glider was most probably one of those taking part. The competition task was a triangular cross-country flight departing from Bacchus Marsh, tracking southwest to Derrinallum, then north west to Buangor, then returning to Bacchus Marsh.

Bacchus March is situated under the 2,000 foot step of Melbourne CTA. On the day of the competition "Area Alpha", a specially released block of airspace over Bacchus Marsh with a 4,000 foot ceiling, gave pilots a higher start level over the airfield.  The south-eastern boundary of the 4,000 foot CTA step is located one mile to the west of the airfield. The competition track progressed under the 4,000, 6,000, 8,000 and 10,000 foot CTA steps.

Prior to take-off the pilots were briefed by the contest organiser who had arranged the task based on the weather forecast for the day, which indicated that thermals would go to 8,000 feet. The briefing covered task details, weather, safety and some airspace considerations. Pilots were not provided with airspace maps by the organiser, nor did the briefing involve airspace higher than 8,000 feet.

The weather for the day was much better than forecast with reports of some gliders taking part in the competition reaching 12,000 feet in thermals.

At the time of the airspace incursion the gliders were returning from the task. The incursion occurred south of Ballarat within the area of the 6,000 foot CTA step. Had the glider been observing the limitation and flying below the 6,000 foot CTA step, it would have been required to climb in thermals to have reached Bacchus Marsh. This would have slowed the glider's progress.

One aim of pilots in such competitions is to gain as much height as possible and, on the final glide, trade that height for speed to arrive over the airfield with just sufficient height to finish, conduct a circuit, and land. The pilot involved in the incursion would probably have been taking advantage of the strong conditions to maximise his competitive advantage and was either not aware of, or was not respecting, the airspace boundaries of the area in which he was flying.  Because of the smoke from the bushfire, it is doubtful that the glider pilots were able to achieve the visual navigation accuracy needed when flying close to CTA step boundaries.

Glider pilots do not receive training in airspace to the same extent as the pilots of powered aircraft. They also do not hold a licence issued by the Civil Aviation Authority (CAA) and consequently do not receive advice from the CAA in regard to availability of airspace maps and associated information.

The gliding fraternities' understanding and respect of airspace, and the quality of briefings, has been the subject of a previous accident report. (Ref 9303898 VH-AYB, GMN, Benalla 24 November 1993).

Significant Factors

The following factors were considered relevant to the development of the incident:

1. Glider pilots taking part in the competition were inadequately briefed in regard to airspace requirements.
2. Glider pilots do not receive formal training in airspace considerations.
3. The pilot was either not aware of or was not respecting the airspace limitations.
4. Smoke from a bushfire would have made visual identification of CTA step boundaries difficult.
5. The glider was flown in controlled airspace without a clearance.

Safety Action

This ASOR is to be referred to the Gliding Federation of Australia to reinforce the need for increased awareness of these matters. (Ref SADN 950070).