Moore, ID, USA
N559Y
BRIEGLEB BG-12B
The pilot of the experimental amateur-built glider was returning to land after a 2-hour flight. Witnesses located on the airfield were startled as the glider flew inbound with a tailwind 75 feet over the runway at a high speed. The glider then began a smooth pitch up and a wingover-type maneuver in a presumed effort to return for landing. During the maneuver, the glider stalled and spun to the ground. The pilot had arrived at the airfield earlier in the week for a fly-in, and had flown the glider uneventfully twice since arriving. Witnesses, who were also friends of the pilot, expressed astonishment that he performed the low pass and wingover maneuver, stating that such a flamboyant maneuver was completely out of character. The pilot purchased the vintage glider about 4 years before the accident, and the fly-in was the first time he had flown it. He held a commercial pilot certificate for gliders and powered airplanes, and had accumulated extensive experience flying hang gliders and paragliders. Additionally, he owned a modern glider, which would have had markedly different performance characteristics than the accident glider. Although the most recent condition inspection had been performed on the glider 4 years before the accident, examination of the wreckage did not reveal any anomalies with the airframe that would have precluded normal operation. About 2 years before the accident (and after his most recent FAA medical certificate application), the pilot’s personal physician described signs of depression, including mood swings, elevated mood, compulsive behaviors, obsessive thoughts, and poor insight. As such, he prescribed medication to control these conditions, as well as medication for hypertension, which had been diagnosed previously. About 6 months before the accident, the pilot was also diagnosed with and prescribed medication for hyperlipidemia; he was still under treatment for prior diagnosed conditions. At that time the physician noted that his depression was under “fair control.” However, postmortem toxicological analysis revealed that he had not been taking any of his prescribed medications at the time of the accident. As such, it is possible that he was experiencing symptoms of his medical conditions, including compulsive behavior, at the time of the accident. Although the pilot’s judgment could have been affected by the symptoms of hypoxia or dehydration, it was not possible to determine if he was experiencing these conditions.
HISTORY OF FLIGHT On August 18, 2011, about 1640 mountain daylight time, a Briegleb BG-12B, N559Y, collided with terrain during approach to King Mountain Glider Park Airport, Moore, Idaho. The pilot was operating the experimental amateur-built glider under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot sustained fatal injuries; the glider was substantially damaged during the accident sequence. The local flight departed King Mountain at 1436. Visual meteorological conditions prevailed, and no flight plan had been filed. At the time of the accident, an annual Fly-In was underway at the airport. The pilot had arrived earlier in the week, and airfield records indicated that he flew the glider two times during the period prior to the accident. A witness, who was located midfield under an awning on the east verge of the runway was seated and facing northwest, when he heard the pilot report on the common traffic advisory frequency that he was inbound for landing. A few minutes later, his attention was drawn to a glider flying past the awning in level flight, heading north along runway 34 at an altitude of about 75 feet above ground level (agl). He did not see the glider prior to that moment, and while he could not accurately judge its airspeed, he surmised that it was traveling at a speed higher than appropriate for the glider type. He was startled, and expressed considerable alarm at the glider's position relative to the airfield. The glider continued to the end of the runway, and then began a smooth pitch-up maneuver. During the initial climb, the right wing dropped slightly, and the glider proceeded to bank smoothly to the left. The turn continued until its heading had diverged by about 40 degrees, at which point the glider had slowed down significantly. It reached the apex of the climb, and was about 300 feet agl, when it began a spin to the left in a near vertical, nose-down attitude. It completed one full rotation before disappearing out of his view behind trees. The flaps did not appear to be deployed at any point during the maneuver. The witness, who was an acquaintance of the pilot, stated that it was extraordinarily unusual, and completely out of character, to see the pilot perform such a low-pass maneuver. He further reported that the pilot was methodical and deliberate, and this compounded his shock as he observed the glider initially overfly the field. The pilot had earlier stated to the witness that the prior flights that week were uneventful, and the glider was performing well. Multiple witnesses and acquaintances recounted similar observations and encounters with the pilot, all reporting that at the time of the accident, the wind was out of the south between 10 and 20 knots. PERSONNEL INFORMATION A review of Federal Aviation Administration (FAA) airman records revealed that 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 on June 1, 2009, with limitations that he must wear lenses for distant vision, and have glasses for near vision. No personal flight records were located for the pilot; however, on his most recent application for a medical certificate, he reported a total time of 4,267 flight hours. FAA records revealed that at the time of the accident, the pilot owned an AS+LTD - AC 4 Glider manufactured in 1996, a Cessna 172M, and a Boeing A75N1. Acquaintances further reported that he had accumulated extensive experience flying both hang gliders and paragliders. GLIDER INFORMATION The plans-built, single-seat glider was comprised primarily of wooden construction, and received its special airworthiness certificate in 1965. FAA registration records indicated that the pilot purchased the glider in March 2007. Examination of the maintenance logbooks revealed that the most recent conditional inspection was accomplished in March 2007, at a total airframe time of 286.2 flight hours. Associates of the pilot reported that he purchased the glider about 4 years prior to the accident, and the fly-in was the first time he had flown it since purchase. METEOROLOGICAL An NTSB meteorologist completed a weather study. The closest weather reporting station to the accident site was an Automated Weather Observing System (AWOS-3) located at Friedman Memorial Airport (elevation 5,320 feet), 52 miles southwest of the accident site. Seven minutes after the accident, the station disseminated wind from 200 degrees at 8 knots, gusting to 12 knots; 10 miles visibility and clear skies; temperature at 28 degrees C; dew point 2 degrees C; and an altimeter setting of 30.08 inches of mercury. A National Weather Surface (NWS) Surface Analysis Chart for 1500 depicted a cold front east of the accident site, stretching from eastern Idaho east-northeastward into central North Dakota. According to the meteorologist, the accident site was within mountainous terrain where mostly clear skies and daily afternoon surface wind increases along the terrain would normally be expected. The NWS Storm Prediction Center archive, Constant Pressure Charts for 1800 depicted a mid-level trough at 500-hPa north of the accident site. The magnitude of the cross barrier flow wind component at 700-hPa was not strong enough to expect the formation of mountain wave induced turbulence below 15,000 feet. A full meteorological report is contained within the accident docket. A video of the glider's takeoff revealed that the wind was calm at the time of departure. AIRPORT INFORMATION King Mountain Airpark is located at the southern end of the Lost River Mountain Range, on the western foothills of King Mountain. From the airports elevation of 5,500 feet, the terrain rises to the North King Mountain Peak at 10,780 feet, 4.5 miles to the northeast. The airport was comprised of a single 3,900-foot-long, 120-foot-wide turf runway, oriented on a heading of 160 and 340 degrees magnetic. The airport was surrounded by level terrain comprised of ploughed agricultural fields. FLIGHT RECORDERS The glider was equipped with a Bräuniger Flugelectronic, IQ-Basis II Variometer. According to the manufacturer, the unit was capable of recording the maximum climb rate, maximum speed, and maximum altitude of the last 10 flights. The unit was sent to the NTSB Office of Research and Engineering for data extraction; however, no recorded data was present within the devices memory. WRECKAGE AND IMPACT INFORMATION The glider came to rest about 600 feet north of the arrival end of runway 16, in a field consisting of brush and rubble. The entire cabin area forward of the wing leading edge was fragmented, with the tailcone and empennage remaining relatively intact. The tail section came to rest in a level attitude, on a heading of 270 degrees magnetic. The first identified point of impact consisted of a 6-inch-deep ground disruption, centered in the area of the fragmented cabin remnants. Two 16-feet-long and 4-inch-deep ground scars emanated outward from the disruption, on a heading of 72 and 252 degrees, respectively. Both wings remained attached to the center box section, which had become separated from the fuselage. All sections of the glider were accounted for at the accident site. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was conducted by Western Pathology Associates LLC., under the auspices of the Butte County Coroner. The cause of death was reported as blunt force trauma, with findings of Nephrosclerosis, mild to moderate, and Atherosclerotic heart disease, mild to moderate. Toxicological tests on specimens from the pilot were performed by the FAA Civil Aerospace Medical Institute (CAMI). Analysis revealed no findings for carbon monoxide, or cyanide. The results were negative for all screened drug substances and ingested alcohol. Refer to the toxicology report included in the public docket for specific test parameters and results. Current toxicological analysis does not permit the identification of antemortem hypoxia or hydration state in post mortem tissues. Personal Medical Records Review of the pilot's personal medical records from his primary care physician for the period April 2007 to February 2011, revealed that he had been prescribed the medications, Bupropion (Welbutrin, Zyban), and Paroxetine (Paxil), as well as medication for the treatment of hypertension. The records revealed that he had been suffering from Hypertension, Depression, Hyperlipidemia, and Sleep Disturbance during that period. His personal medical records, dated June 12, 2009, 11 days after his FAA medical examination, included a psychiatric evaluation with the observation of, “Mood swings. Elevated mood. Exhibits compulsive behaviors. Obsessive thoughts. Poor Insight.” The primary care physician's assessment at the pilot’s final medical examination, dated February 21, 2011, noted that his Depression was under “fair control,” his Sleep Disturbance was “stable,” Hyperlipidemia under “poor control,” and that his Hypertension was “chronic.” The evaluation further stated that at that time, he was actively taking Lisinopril, Paxil, Hydrochlorothiazide, and Fluticasone Propionate. At the time of the pilot's most resent FAA medical certificate application, he recorder “no” to all questions regarding medical history, including, “Have you ever in your life been diagnosed with, had, or do you presently have any of the following:”, ”Mental disorders of any sort; depression, anxiety, etc.”, “Heart or Vascular trouble.”, ”High or low blood pressure”. He also stated that he was not currently using any medication. TESTS AND RESEARCH The airframe was examined at the accident site by the NTSB investigator-in-charge, and inspectors from the FAA. The vertical stabilizer remained attached to the tailcone, with the rudder firmly attached to the stabilizer. All rudder hinges remained intact, and no binding was noted. The rudder horns remained attached to their control cables, which were continuous to the foot pedals. The horizontal stabilizer remained attached to the tailcone. The right elevator remained attached to the stabilizer, with all hinges intact. The elevator control push-pull tubes sustained bending damage and fragmentation through to the control stick. The grip portion of the control stick had separated at its weldment. The surface features at separation were granular in appearance, and no indication of preexisting cracking was present. The flap control lever had become separated from the airframe and detent plate. The detent plate exhibited a fresh cut to the wood backing panel, adjacent to the fully retracted flap position. The airspeed indicator glass bezel had been shattered, with the indicator needle pointing to the 36 knots position. The altimeter indicated 5,340 feet, with the Kollsman window set to 30.16 inches of mercury. The aileron control push-pull tubes sustained bending damage and fragmentation from the control surfaces through to the control stick. The pitot static system sustained heavy fragmentation damage, and as such, its operational status at the time of the accident could not be determined. An empty oxygen canister was recovered from the wreckage adjacent to the location of the pilot; its valve was in the open position. The bottle remained attached to a Mountain High E&S Co. Electronic Diluter Demand O2 Delivery System (EDS model A). The unit appeared set to the off position, and in demand mode (automatic operation above 11,000 feet). The switches were of the toggle type, and as such, an accurate assessment of their position at the time of impact could not determined. Due to the fragmentation sustained to the cabin area, it could not be determined if the pilot was wearing the nasal cannula at the time of the accident. No water bottles or additional means for pilot hydration were located in the wreckage. Examination did not reveal any anomalies with the airframe that would have precluded normal operation. A full examination report is contained within the accident docket.
The pilot’s decision to perform a low pass over the runway in the opposite direction of his intended landing, and his subsequent failure to maintain airspeed and glider control during the reverse-course maneuver. Contributing to the accident was the effect of the pilot's failure to take his prescribed medications.
Source: NTSB Aviation Accident Database
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