Schempp-Hirth Flugzeugbau Gmbh VENTUS 3F N753R accident near Moriarty, New Mexico

Probable cause

The pilot's exceedance of the glider's critical angle of attack during a low-altitude turn, which resulted in an aerodynamic stall and subsequent impact with terrain.

NTSB analysis

The private pilot was conducting a local flight in his motorglider in day visual meteorological conditions. Another glider pilot in the area reported hearing the accident pilot announce over the radio that he was not getting any lift and was going to stay near the airport. About 2 hours after the pilot departed on the flight, a witness on the ground saw the glider as she was driving near the airport. The glider was in a nose-down attitude very close to the ground; she thought that it might be landing. She subsequently turned her car and lost sight of the glider.

A search was initiated when the glider did not return to the airport as expected, and the wreckage was located about 1/2 mile southeast of the airport. The glider was equipped with a FLARM, which is an onboard collision avoidance system that recorded the glider's flight track, altitude, groundspeed, and engine noise level (ENL). The ENL value increased during the last 4 minutes of flight and then began to fluctuate during the last 13 seconds, both of which are indicative of engine use. FLARM data that were sent to a ground station indicated that, about 11 seconds before impact, the glider entered a left descending turn about 560 ft above ground level; the turn continued until just before impact. The FLARM data could not be correlated with the glider's airspeed, thus the glider's airspeed during the turn could not be determined.

Witness marks on the ground and the structural damage observed at the scene indicated that the glider impacted the ground with the left wingtip immediately followed by the left wing, the engine and propeller, and cockpit. The upward and aft crushing damage was consistent with the glider impacting the terrain in a steep nose down attitude, characteristic of a low-altitude aerodynamic stall. Examination of the airframe and engine revealed no evidence of preimpact anomalies that would have precluded normal operation.

The accident pilot had purchased the glider several months before the accident. Although he had logged over 1,300 hours of flight experience in gliders , the pilot had logged less than 10 hours in the accident glider.

Based on the impact damage, it is likely that during the left descending turn, after the last recorded data from the FLARM, the airplane pitch exceeded the critical angle of attack resulting in an aerodynamic stall causing the glider to descend to the ground in a steep nose down pitch attitude.

Text from the NTSB. Open the NTSB docket for CEN18FA262 for the full record.