History of Flight
On August 18, 2011, about 1640 mountain daylight time, a Briegleb BG-12B glider (registration N559Y) collided with terrain during approach to King Mountain Glider Park Airport in Moore, Idaho. The pilot was operating the experimental amateur-built glider under Title 14 Code of Federal Regulations Part 91. The local flight departed King Mountain at 1436. Visual meteorological conditions prevailed, and no flight plan had been filed.
An annual Fly-In was underway at the airport. The pilot had arrived earlier in the week and had flown the glider two times prior to the accident.
A witness located midfield under an awning on the east verge of the runway heard the pilot report inbound on the common traffic advisory frequency. Moments later, the witness saw the glider in level flight heading north along runway 34 at about 75 feet above ground level (agl). The witness, who could not accurately judge airspeed, believed the glider was traveling faster than appropriate for the type. The glider continued to the end of the runway and began a smooth pitch-up. During the initial climb, the right wing dropped slightly, and the glider banked left. The turn continued until the heading diverged about 40 degrees, at which point the glider had slowed significantly. At the apex of the climb, about 300 feet agl, the glider entered a spin to the left in a near-vertical nose-down attitude, completing one rotation before disappearing behind trees. The flaps did not appear deployed during the maneuver.
The witness, an acquaintance of the pilot, stated the low-pass maneuver was extraordinarily unusual and out of character for the pilot, who was methodical and deliberate. The pilot had earlier reported that prior flights that week were uneventful. Multiple witnesses reported wind out of the south between 10 and 20 knots.
Personnel Information
The 55-year-old pilot held a commercial pilot certificate with ratings for airplane single-engine land, multiengine land, instrument airplane, and glider. He held a second-class medical certificate issued June 1, 2009, with limitations requiring corrective lenses for distant and near vision. On his most recent FAA medical application, he reported 4,267 total flight hours.
FAA records showed the pilot owned an AS+LTD - AC 4 Glider (1996), a Cessna 172M, and a Boeing A75N1. Acquaintances reported extensive experience in hang gliders and paragliders.
Glider Information
The plans-built, single-seat glider was primarily of wooden construction and received its special airworthiness certificate in 1965. FAA records indicated the pilot purchased the glider in March 2007. The most recent conditional inspection was in March 2007 at a total airframe time of 286.2 flight hours. Associates reported the pilot bought the glider about four years prior, and the Fly-In was the first time he had flown it since purchase.
Meteorological Information
An NTSB meteorologist completed a weather study. The closest weather reporting station was Friedman Memorial Airport (elevation 5,320 feet), 52 miles southwest. Seven minutes after the accident, it reported wind from 200 degrees at 8 knots gusting to 12 knots, 10 miles visibility, clear skies, temperature 28°C, dew point 2°C, and altimeter 30.08 inches of mercury. A National Weather Surface Surface Analysis Chart for 1500 showed a cold front east of the accident site. The meteorologist noted the site was in mountainous terrain where mostly clear skies and afternoon surface wind increases were expected. Constant Pressure Charts at 500-hPa showed no strong cross-barrier flow prone to mountain wave turbulence below 15,000 feet. A video of the glider's takeoff showed calm wind at departure.
Airport Information
King Mountain Airpark is at the southern end of the Lost River Mountain Range on the western foothills of King Mountain. The airport elevation is 5,500 feet, with terrain rising to North King Mountain Peak at 10,780 feet, 4.5 miles northeast. The airport has a single 3,900-foot-long by 120-foot-wide turf runway oriented 160/340 degrees magnetic, surrounded by level ploughed fields.
Flight Recorders
The glider was equipped with a Bräuniger IQ-Basis II Variometer, which records maximum climb rate, speed, and altitude for the last 10 flights. The unit was sent to NTSB for data extraction, but no recorded data was present in the device's memory.
Wreckage and Impact Information
The glider came to rest about 600 feet north of the arrival end of runway 16 in a field of brush and rubble. The cabin area forward of the wing leading edge was fragmented; the tailcone and empennage remained relatively intact. The tail section rested level on a heading of 270 degrees magnetic. The first point of impact was a 6-inch-deep ground disruption centered amid fragmented cabin remnants, with two 16-foot-long, 4-inch-deep ground scars on headings of 72 and 252 degrees. Both wings remained attached to the center box section, which had separated from the fuselage. All sections were accounted for.
Medical and Pathological Information
An autopsy by Western Pathology Associates LLC under the Butte County Coroner listed cause of death as blunt force trauma, with findings of mild to moderate Nephrosclerosis and mild to moderate Atherosclerotic heart disease. Toxicological tests by FAA CAMI showed no carbon monoxide, cyanide, or screened drugs/alcohol.
No personal flight records were located. On his FAA medical application, the pilot answered "no" to questions regarding mental disorders, heart trouble, blood pressure, and medication use. However, personal medical records from April 2007 to February 2011 revealed prescriptions for Bupropion, Paroxetine, and hypertension medication. Records indicated diagnoses of Hypertension, Depression, Hyperlipidemia, and Sleep Disturbance. A psychiatric evaluation on June 12, 2009, noted mood swings, elevated mood, compulsive behaviors, obsessive thoughts, and poor insight. The primary care physician's assessment on February 21, 2011, described Depression as under "fair control," Sleep Disturbance "stable," Hyperlipidemia "poor control," and Hypertension "chronic." At that time, the pilot was taking Lisinopril, Paxil, Hydrochlorothiazide, and Fluticasone Propionate.
Tests and Research
NTSB and FAA inspectors examined the airframe at the accident site. The vertical stabilizer and rudder were intact with continuous control cables to foot pedals. The horizontal stabilizer and right elevator were attached; elevator control push-pull tubes showed bending damage and fragmentation. The control stick grip had separated at its weldment with no preexisting cracking. The flap control lever had separated from the airframe; the detent plate exhibited a fresh cut near the fully retracted flap position. The airspeed indicator needle pointed to 36 knots; the altimeter indicated 5,340 feet with Kollsman window set to 30.16 inches of mercury. Aileron control push-pull tubes also showed bending damage and fragmentation. The pitot static system was heavily fragmented and its operational status could not be determined. An empty oxygen canister with open valve was recovered, attached to a Mountain High EDS diluter demand system set to off. Toggle switches could not be assessed. It could not be determined if the pilot was wearing the nasal cannula. No water bottles or hydration means were found. No airframe anomalies were found that would have precluded normal operation.