Accident Scenario
A Robinson helicopter, operated by a certified flight instructor (CFI) and a student, had been flying for approximately 46 minutes. The CFI elected to conclude the training session with a demonstration of a 180-degree autorotation. Meanwhile, a Piper airplane had been towing gliders and, after landing following a previous tow, was preparing for another departure with a glider connected.
Sequence of Events
An occupant of the helicopter announced on the common traffic advisory frequency (CTAF), "North County traffic helicopter one Zulu Gulf is turning left downwind at (500) feet for practice one eighty autorotation North County." The Piper pilot reported seeing the helicopter at the start of its downwind leg and made a takeoff announcement on the CTAF. Recorded CTAF transmissions did not include ground communications.
Witnesses observed the helicopter on the downwind leg while the airplane began its takeoff roll. The helicopter then made a left turn. The pilot of the glider being towed noted the helicopter slightly above and behind to his left, paralleling the airplane's flight path.
The airplane and helicopter collided. Following the collision, the airplane continued straight ahead for a short distance before descending nose- and left-wing-low into a marsh. The helicopter impacted the ground.
Postaccident Examination
Examination of both aircraft revealed that the helicopter's main rotor contacted the left main landing gear tire and a section of the leading edge of the left wing of the airplane.
Airport Operations
The airport did not have a memorandum of agreement with any operators at the airport pertaining to helicopter and fixed-wing operations to runway 8L.