On August 7, 1994 at 1400 eastern daylight time, N245JD, a Rolladen-Schnieder LS-4A glider, collided with trees on high terrain, in Franconia, New Hampshire. Visual meteorological conditions existed. The certificated commercial pilot, the sole occupant, was not injured. The glider was substantially damaged. The departure point was Franconia. The flight was operated under 14 CFR Part 91. Shortly after the pilot released from the towplane, he circled in a thermal southwest of the peak of Cannon Mountain. According to the pilot, "I started to thermal in a counter-clockwise circle. As I came around one rotation, the lift changed to sink abruptly." The pilot then lowered the nose of the aircraft and steepened the turn to avoid the ridge; however, the glider stalled, descended, and impacted trees on the ridge. The pilot stated the accident could have been prevented had he not established the thermal circle so close to the ridge, causing him to be unable to adequately maneuver in (south west blowing) air.