Schleicher ASW 28 18E accident near Ephrata, Washington, May 26, 2017

The NTSB's narrative final · quoted from the NTSB record

The private pilot of the glider received a tow to 3,000 ft above ground level. Recorded data from an onboard GPS device showed that the glider proceeded in a general westerly direction until it was about 15 nautical miles from the departure airport. It then turned and tracked eastward for the remainder of the flight. The data ended about 9 miles west-northwest of the departure airport. During the 43 minutes of recorded data, the glider reached a peak altitude of about 8,500 ft, slowly descended to about 3,900 ft, then entered another gradual descent that continued until ground contact. During the last 8 minutes of recorded data, the glider's speed was recorded slowly decreasing from about 76 to 40 knots. The glider came to rest in a dry, plowed field slightly northwest of the last GPS target. The engine was stowed and secure, and examination revealed no mechanical malfunctions or anomalies of the glider that would have precluded normal operation.  The pilot received his private pilot certificate about one year before the accident and purchased the accident glider a few days later. The pilot's first flight in the glider occurred about 3 weeks before the accident from the accident airport. The accident flight was the pilot's second flight in the accident glider. It could not be determined whether the pilot obtained training specific to the accident glider or in motorglider operations. The flight track data was consistent with normal glider operations and a slow descent to land. However, the on scene impact marks, the contained debris field, and the damage to the wreckage were all consistent with a stall. Therefore, it appeared that the pilot was attempting to make an off-field landing when the glider stalled and impacted the ground. It is unknown why the pilot did not use the airplane's engine; however, it was noted that very little fuel was removed from the glider at the accident site.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.