Operational event involving a Robinson R22 Alpha, VH-NOC, 18 km north-east of Darwin, Northern Territory, on 14 December 1994

The pilot had been undergoing dual instruction and had been practicing autorotational landings onto a dry mud flat.

One exercise was for the instructor to hold the anti-torque pedals firmly in the neutral position simulating jammed pedals, the pilot terminating the exercise with a run on landing. He made an approach to a larger, and clearer area of the mud flats, but his initial pass was too slow, and he was unable to maintain directional control. The instructor took over and completed the exercise as a demonstration, touching down in a straight and level attitude, with a ground speed of approximately 10 kt.

Immediately after ground contact the landing skids broke through the firm top layer of the mud crust, causing the helicopter to pitch forward allowing the main rotor blades to contact the ground. The helicopter then cartwheeled and came to rest on its left side, facing back along the approach path.