Circumstances
A glider pilot was approaching a gliderport for landing. During the downwind leg, the pilot observed another glider and a tow airplane on the runway. To allow them to depart, the pilot extended the downwind leg.
Sequence of Events
After turning onto final approach for the runway, the glider encountered an unexpected headwind. While on final approach, the pilot noticed a row of trees ahead that he assessed he would not be able to clear. The pilot then turned the glider to the right and initiated a landing to an adjacent field.
During the attempted landing, the pilot later stated, "[The pilot] allowed the airspeed to get too slow." At an altitude of about 30 feet above ground level, the glider stalled, spun to the right, and impacted the terrain.
Probable Cause
The pilot allowed the airspeed to get too slow, resulting in a stall and spin at about 30 feet AGL.