The purpose of the flight was to achieve the cross-country distance requirements for the upgrading of the pilot's qualifications. He had been airborne for over 6 hours when further lift could not be found and an outlanding became necessary. While manoeuvring towards the selected area, the pilot misjudged the strength of the wind and was forced to turn onto final approach at a low height above the ground. During the turn the right wingtip struck a tree and the aircraft rotated about 110 degrees to the right before striking the ground. It was considered likely that the pilot's performance was affected by fatigue resulting from the length of the flight and his exposure to direct sunlight for a period of more than 10 hours. This accident was not the subject of an on-scene investigation.