NTSB Factual Report

HISTORY OF FLIGHT

On April 11, 2015, about 1525 mountain standard time, a Schempp-Hirth, Standard Cirrus glider, sustained substantial damage after impact with terrain following a winch-tow-launch and initial climb at the A.C. Goodwin Memorial Field Gliderport (AZ86), Prescott Valley, Arizona. The private pilot, who was the sole occupant of the glider, sustained fatal injuries. The glider was registered to and operated by the Prescott Soaring Society, Prescott, Arizona. Visual meteorological conditions prevailed at the time of the accident, and a flight plan was not filed. The proposed local flight, which was being operated in accordance with 14 Code of Federal Regulations Part 91, was originating at the time of the accident.

Several witnesses to the accident provided written statements to the National Transportation Safety Board investigator-in-charge. One witness, who was also a pilot with the glider club, reported that the accident aircraft had been flown twice earlier in the day. The witness stated that prior to the accident pilot departing, he advised him of the difficulties in flying the Standard Cirrus, in that it had a "touchy elevator", and that things seemed to happen fast in a fiberglass glider. The witness further stated that the pilot launched using the winch launch in the normal fashion, and had called ahead and requested a speed of 65, which he called out/verbalized. The witness opined that while watching the launch, it appeared the glider was going slower with an increase in angle of attack; a few seconds later he reported hearing a call [on the radio] of "more power." The witness reported that the glider was about 800 feet above the ground (agl), when he turned to go to the radio to advise the pilot that he was too slow, which is when he heard another witness say "Oh no"; when he looked back he observed the glider in a stall spin to the left prior to impact with terrain.

Another witness reported that the launch was slightly bumpy, and that during the climb he observed the wings begin to flutter and then stalled. The left wing [then dropped], followed by the glider spinning two full times at about a 75-degree angle prior to impact with terrain.

A third witness reported observing the glider launch, climb to about 800 feet agl, slowed below stall speed, and then spun between two and one-half and three times before impact with terrain.

A fourth witness stated that the launch appeared to be a very smooth transition into the climb, at what he estimated to have been about 800 feet agl, when the glider appeared to fly through a thermal. The witness stated that at this point the glider's wings wobbled, first to the right, then to the left. Shortly thereafter, the pilot gave out a speed reading of 65 mph, shallowed out his climb, and then call for "more power." The witness stated that at this time, he estimated that the glider was between 1,200 to 1,300 feet agl, when the aircraft stalled then spun two and one-half times to the left at an angle of between 70 to 80 degrees before impact with terrain was observed.

The individual who was operating the tow winch at the time of the accident reported that the winch is located about a mile down the main runway from the initial takeoff point. The operator opined that the pilot made a standard radio call that he was ready to launch, and that he requested a reference speed of 65 mph. The operator stated that he then added power and saw what appeared to be a normal takeoff and initial climb out, during which the pilot called his speed as 65, which indicated that the winch power setting was as desired for the tow. The operator added that he heard the pilot call what sounded like "more power," which according to the operator is not a standard call; a normal call would be one which would indicate power needs by calling an airspeed above or below the desired reference speed. The operator stated that he began to add additional power, but almost immediately saw the nose of the glider drop as the glider entered a spin. The operator reported that at this point he cut the power on the winch, and put the transmission in neutral to release any tension on the tow line. He concluded by saying that he did not see the glider impact terrain, as there was a small hill between the winch and the impact point.

PERSONNEL INFORMATION

The pilot, age 74, possessed a private pilot glider rating. The pilot's initial glider flight under dual instruction was on November 10, 2005; he soloed on March 6, 2006, following 15.4 hours of instruction. The pilot received his private pilot glider rating on March 21, 2015, at a total time of 132 hours. All pilot time logged was exclusively in glider aircraft.

A review of the pilot's personal logbook revealed that at the time of the accident he had accumulated a total time of 134.8 hours, 87.7 hours as pilot-in-command, with 9.4 hours in make and model; there was no record to indicate that the pilot had received instruction in make and model. It was further revealed that the pilot had made a total of 222 ground tow launches, 168 which were performed as pilot in command, and 54 performed while having received dual instruction. Additionally, it was revealed that the pilot had made a total of 13 ground tow launches in make and model, all of which were in the accident glider as pilot in command. Prior to the accident, the most recent ground tow launch in make and model was performed on March 23, 2014, which was in the accident glider.

AIRCRAFT INFORMATION

The glider, serial number 126, was issued its standard airworthiness certificate in September of 1971. A review of the aircraft's maintenance records revealed that the last annual inspection was performed on March 26, 2015, at an airframe total time of 1,144.6 hours.

METEOROLOGICAL INFORMATION

At 1545, the weather reporting facility at the Ernest A. Love Field (PRC), Prescott, Arizona, which was located about 7 nautical miles west-southwest of the accident site, reported wind variable at 6 knots, visibility 10 miles, sky clear, temperature 21 degrees C, dew point -9 degrees C, and an altimeter setting of 29.94 inches of mercury.

WRECKAGE AND IMPACT INFORMATION

A survey of the wreckage site revealed that the glider had impacted flat, desert-type terrain in a steep nose down attitude, about 215 feet west of runway 21, the departure runway, and about 2,490 feet from the point where the takeoff run had commenced. The glider came to rest on its left side on a measured magnetic heading of about 170 degrees. The first point of impact was evidenced by a relatively shallow depression, which measured about 6 inches in depth, and located about 30 feet east of the main wreckage. The direction of the first point of impact could not be determined.

The carry-through wing remained intact and upright laying on top of the cabin/cockpit area, with its entire leading edge facing aft, having rotated about 180 degrees during the accident sequence, and oriented nearly perpendicular to the aft fuselage.

The forward fuselage and cockpit area was crushed rearward. The aft fuselage was observed intact to the empennage, where a circumferential fracture was observed in the fiberglass. The vertical stabilizer was intact, with the rudder having remained attached to the stabilizer at all attach points. The left stabilator, which was attached to the top of the vertical stabilizer remained attached at all attached points. The right stabilator was observed separated from the vertical stabilizer, and located about 20 feet north of the main wreckage.

The outboard one-third of the left wing was observed intact, with moderate damage due to impact forces. The inboard two-thirds of the wing was not damaged. The left aileron was not damaged, and remained attached to the trailing edge of the wing at all attach points. The left spoiler was observed in the deployed position.

The inboard one-half of the right wing, both upper and lower surfaces, was substantially damaged due to impact forces. The outboard one-half of the wing was intact, with only minor damage observed. The right aileron was intact, not damaged, and remained attached to the wing's trailing edge at all attach points. The wing's spoiler was observed in the deployed position.

The single-place cockpit was destroyed as a result of impact forces. Flight control continuity was verified to the rudder and ailerons. Additionally, stabilator control through the fuselage via stabilator pushrods to the vertical stabilizer was verified.

An examination of the tow rope attachment revealed no anomalies that would have precluded normal operation. Additionally, the tow winch operator reported no anomalies with the tow winch system, which had been used to launch several flights on the day of the accident.

MEDICAL AND PATHOLOGICAL INFORMATION

On April 12, 2015, an autopsy on the pilot was performed at the Yavapai County Office of the Medical Examiner, Prescott Valley, Arizona. The results of the autopsy revealed that the pilot sustained fatal injuries as a result of multiple blunt force trauma.

Toxicological testing was performed on the pilot by the FAA Bioaeronautical Science Research Laboratory, Oklahoma City, Oklahoma. Review of the toxicology report revealed no carbon monoxide detected in Blood, no ethanol detected in Vitreous, and testing for cyanide not performed. Tests for drug revealed Flecainide and Tamsulosin detected in Liver and Blood.

Flecainide is a medication used to treat certain types of irregular heartbeat, and commonly known as an anti-arrhythmic drug.

Tamsulosin is an alpha-blocker that relaxes the muscles in the prostate and bladder neck, making it easier to urinate.

NTSB Probable Cause

The pilot’s failure to maintain adequate airspeed and his exceedance of the glider’s critical angleofattack during the initial climb after a ground-tow launch, which resulted in an aerodynamic stall/spin.