On October 27, 1993, at 1430 Hawaiian standard time, a Schweitzer SGS 2-33A, N7779S, struck a tree with the right wing while soaring along a ridge line. The student pilot was conducting a local visual flight rules solo instructional flight. The glider, operated by Honolulu Soaring Club, Inc., sustained substantial damage. The student pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. The flight originated at Dillingham Airfield, Waialua, Hawaii, at 1330 Hawaiian standard time. According to FAA Inspectors, the student pilot was operating in weak ridge conditions and encountered a sinking air mass. In so doing, the right wing of the glider struck a tree. The pilot was able to continue the flight and landed at Dillingham Airfield without further incident. An off-duty FSDO supervisor saw the aircraft in the hangar and noticed damage which consisted of a five inch dent in the leading edge between the third and fourth wing ribs, counting inboard from the tip. The skin was severely wrinkled, extending from the impact point on the leading edge, aft to the trailing edge.