Lehi, UT, USA
N127JK
KNELL ASC SPIRIT
The private pilot of the experimental, amateur-built glider was conducting a local flight. The tow plane pilot reported that, as the glider pilot approached the privately owned airport, he announced over the radio his intent to land. He and one witness in the area reported seeing the glider circling to land and making several steep turns during the descent. When the glider was about 30 to 40 ft above ground level, the nose suddenly dropped, and the glider then descended straight down into the ground short of the runway. Another witness reported that it looked like the glider had stalled. Wreckage documentation indicated that the glider impacted terrain in a steep, nose-down, left-wing-low attitude with little forward motion, which is consistent with a stall. Postaccident examination of the airframe revealed no anomalies that would have precluded normal operation. It is likely that the pilot exceeded the glider's critical angle of attack while maneuvering to land, which resulted in an aerodynamic stall.
HISTORY OF FLIGHTOn June 22, 2014, about 1430 mountain daylight time, an experimental amateur-built, ASC Spirit Glider, N127JK, impacted terrain about one-half mile southeast of the Cedar Valley Airport (UT10), 10 miles west of Lehi, Utah. The glider was owned and being operated by the pilot/builder as a visual flight rules personal local flight under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The solo pilot received fatal injuries. The glider departed UT10, about 1350. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 23, a Federal Aviation Administration (FAA) air safety inspector who visited the accident site, said witnesses reported that the glider was circling to land on runway 35. During the descent, the pilot made several steep turns. When the airplane was about 30 to 40 ft above the ground, the right wing dropped and the glider suddenly nosed into the ground short of the runway. A witness who was the tow-plane pilot, reported that he towed the glider to about 7,500 ft. (mean sea level) where the pilot released from the tow. The tow pilot then landed back at the airfield and met with another glider pilot he was preparing to tow. The witness added that the accident glider made several circles southeast of the airport and then announced over the radio that he was setting up to land on runway 35. He reported that it appeared the accident glider was coming in too steep. He added that he watched as the glider's turns continued to steepen and then the glider descended straight down at an "almost vertical attitude." An additional witness reported that he saw the glider from a distance, and that the glider was about 500-800 ft above the ground, and it appeared to be circling back towards the airport when he lost sight of it. When he saw it again, it appeared to be 30 to 40 ft above the ground. He saw the glider crash south of the airport. A third witness reported that the glider was coming in to land and made a turn. He added that it looked like the glider stalled and crashed nose first. PERSONNEL INFORMATIONThe pilot held a private pilot certificate with a glider rating. The pilot received a third-class medical certificate on October 17, 1995, with the limitation for corrective lenses. No personal flight records were discovered for examination and the pilot's total flying experience was estimated to be about 350 total flight hours. AIRCRAFT INFORMATIONThe airplane was an experimental amateur-built ASC, single-seat, Spirit glider, built by the pilot in 2007. The pilot/builder held a Repairman Experimental Aircraft certificate issued by the Federal Aviation Administration. Maintenance records showed that the last condition inspection (Annual equivalent) was completed by the pilot/builder on May 18, 2013. At the time of the inspection, the glider had accrued a total of 285 flight hours. METEOROLOGICAL INFORMATIONThe closest official weather reporting station, about 7 miles northwest of the accident site, reported sky condition clear, temperature 86 degrees, dew point 36 degrees, altimeter setting 29.95 inches of mercury, wind variable at 4 knots, and visibility 15 miles. The density altitude was calculated to be 7,874 ft. AIRPORT INFORMATIONThe airplane was an experimental amateur-built ASC, single-seat, Spirit glider, built by the pilot in 2007. The pilot/builder held a Repairman Experimental Aircraft certificate issued by the Federal Aviation Administration. Maintenance records showed that the last condition inspection (Annual equivalent) was completed by the pilot/builder on May 18, 2013. At the time of the inspection, the glider had accrued a total of 285 flight hours. WRECKAGE AND IMPACT INFORMATIONAccording to a Utah County Deputy who was dispatched to the accident site, upon arrival, he found the glider about one quarter to one half mile South of the airport. The glider was oriented with the nose pointing southwest. There were imprints in the ground under each wing. There was damage to the tail, cockpit, left wing, and nose. The scattered debris appeared mostly in front of the glider. The pilot's seat and pilot were located outside of the glider and the pilot was wearing a parachute. An FAA air safety inspector examined the glider. The inspector said all the major components of the glider were present, and no mechanical anomalies were found. Photographs provided by the Utah County Sheriff, Spanish Fork, Utah, taken at the accident site were provided to the National Transportation Safety Board (NTSB) investigator-in-charge. Photographs taken the day of the accident showed Visual Flight rules weather conditions at the time the photos were taken. The photos showed the glider upright on the dirt, in a large expanse of flat desert landscape. No trees or large vegetation were visible. No ground-scars were visible at the point of impact. The major structural components of the glider were present. The glider was composite construction, and the nose/cockpit section showed compression fracturing up and aft, consistent with impact at a steep nose-down angle. The cockpit showed a pronounced bend to the left forward of the cockpit's aft bulkhead. The right-wing appeared relatively intact and undamaged. The left-wing showed compression aft and separation forward at the wing-root. The upper and lower left-wing panels had separated along the leading and trailing edges. The vertical stabilizer had folded forward and showed compression fracturing on the upper portion of the joint/intersection with the tail-cone. COMMUNICATIONSPrior to the accident, the pilot of the accident airplane was heard on the airport's universal communications radio frequency (UNICOM) reporting his position and intent to land; no mechanical anomalies were reported. MEDICAL AND PATHOLOGICAL INFORMATIONA postmortem examination of the pilot was completed under the authority of the Utah Department of Health, Office of the Medical Examiner, Salt Lake City, Utah. The pilot's cause of death was attributed to multiple blunt force injuries. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, completed a toxicological examination September 8, 2014. No toxicological anomalies were found.
The pilot’s exceedance of the glider’s critical angle of attack while maneuvering in a steep turn at low altitude, which resulted in an aerodynamic stall.
Source: NTSB Aviation Accident Database
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