What happened
During a scheduled training session intended to transport equipment for an Aero Club to Goulburn, a formation flight was conducted. The mission involved two aircraft, with the lead aircraft being operated by a pilot undergoing formation flying instruction. Prior to the flight, the crew completed a briefing regarding the specific procedures to be followed during the maneuver.
As the aircraft entered the circuit, the pilot of the trailing aircraft expressed concerns regarding the reliability of their airspeed indicator and requested a comparison with the lead aircraft's readings. In response, the pilot of the lead aircraft deployed the landing gear and maintained an indicated airspeed of 96 knots during the first leg of the circuit.
At the conclusion of this initial leg, the pilot executed a sharp left turn. During this maneuver, the nose of the aircraft type dipped, causing the plane to transition into a steep right-hand turn. Although the pilot managed to level the wings and pull the nose up to a level attitude, the aircraft was descending at a very high rate of sink at the moment of impact.
Findings
Investigations into the accident revealed that the pilot had not performed practice maneuvers involving steep turns at such low airspeeds. Furthermore, the pilot lacked sufficient awareness regarding the stalling speed for the specific aircraft configuration and flight attitude being utilized. The pilot was also unable to provide a clear reason for attempting a turn of such extreme bank angle during the flight.