On November 13, 1999, at 1430 central standard time, a Schweizer SGS-1-34, N7646, operated by a commercial glider pilot collided with the terrain following a loss of control while in the traffic pattern to land at Richters Field, East Lynne, Missouri. The pilot was seriously injured and the glider was substantially damaged. The 14 CFR Part 91 flight was operating in visual meteorological conditions prevailed and no flight plan was filed. The local flight originated from Richter Field at 1400 cst. The pilot reported the accident occurred when he returned to land following a local flight. He reported that while on short final to runway 18, at an altitude of 350 feet above ground level (agl), the glider encountered a gust of wind and it turned left of the runway heading. He reported he elected to perform a 360 degree turn to the left to realign the glider with the runway heading. The pilot continued to report that while on a northerly heading "violent turbulence" and a sink rate were encountered. He reported he was unable to level the wings and the glider stalled, impacting the terrain. A glider pilot who witnessed the accident reported seeing the glider at an altitude of approximately 200 feet agl southeast of the runway on a westerly heading. He reported, "I thought it was a reasonable position for right turn to landing, but lower and slower than I would like to have seen." He reported the glider then made a turn to the left (away from the runway), and after about 270 degrees of turn, "...the nose dropped dramatically." He reported he then lost site of the glider. He reported the glider came to rest approximately 100 feet southeast of where it began its turn southeast of the runway. The witness reported they often landed downwind with a wind of 10 knots or less, to minimize ground handling. The location of the wreckage was also comfirmed by the Cass County Sheriff's Office. The pilot reported the local winds were from the northwest at 2 knots. The witness reported the local winds were from 200 degrees at 10 knots. The winds reported at the Kansas City, Richards-Gebaur Memorial Airport, located 18 miles northwest of the accident site were from 220 degrees at 15 knots. This weather observation was taken 23 minutes after the accident occurred.