Tehachapi, CA, USA
N851LT
TRUSTY THORP T-18
The pilot was making an approximate 40-minute flight to his home airport during daylight visual meteorological conditions. After he did not check in at his expected arrival time, his family reported him overdue. The wreckage was subsequently located by a local resident after he observed debris on a road, looked over the edge of a mountain, and saw the accident site. Radar data showed the airplane traversing a mountain range in a straight-and-level flightpath, entering an adjoining valley, and then entering a descent of between 700 and 900 ft per minute. The last radar return was about 15 miles from the accident site, which was located about 200 ft below the ridgeline on the west-facing side of the 4,400-ft-tall mountain. The airplane impacted the rising terrain in a wings-level attitude. Postaccident examination of the airframe and engine revealed no mechanical anomalies that would have precluded normal operation. About 6 months before the accident, the pilot and his wife reported a significant change in the pilot's behavior to the pilot's endocrinologist, who prescribed further medical evaluation and consultation; however, no records of any further evaluation or consultation were found. Postmortem toxicology tests on the pilot identified donepezil, which is used to slow the progression of dementia in Alzheimer's disease. The medication does not carry a specific warning, but it has been associated with fainting, dizziness, and other neurological symptoms in some patients. Although it could not be determined whether the pilot was impaired by the effects of donepezil at the time of the accident and the exact extent of the pilot's cognitive decline could not be determined, it is likely that he was cognitively impaired and, thus, at an increased risk for an accident. The pilot also had other chronic medical problems, including diabetes, hypertension, and high cholesterol. Further, the pilot's autopsy revealed that he had moderate-to-severe coronary artery disease and biventricular hypertrophy, which placed him at risk for impairment or incapacitation from a cardiac event such as acute ischemia or arrhythmia that would not be evident during an autopsy. Thus, he may have been impaired or incapacitated at the time of the accident as a result of his extensive heart disease. Postmortem toxicology testing on the pilot also detected metoprolol (a beta blocker used to treat high blood pressure and control heart rate); however, it is not likely that it impaired the pilot. Further, the testing detected therapeutic levels of the antihistamine doxylamine, which due to its significant sedating effects is also marketed as an over-the-counter sleep aid and carries the warning that, at therapeutic levels, it "may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery)." It is likely that the pilot was impaired by doxylamine at the time of the accident.
HISTORY OF FLIGHT On June 19, 2011, about 1720 Pacific daylight time (PDT), an experimental amateur built Trusty Thorp T-18 airplane, N851LT, impacted a mountain near Tehachapi, California. The pilot/owner operated the airplane under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. The pilot, the sole occupant, was fatally injured; the airplane sustained substantial damage. Visual meteorological conditions prevailed for the flight that departed Santa Ynez Airport (IZA), Santa Ynez, California, about 1630. The flight was destined for Tehachapi Airport (TSP), Tehachapi, and no flight plan had been filed. When the pilot had not checked in with family members upon his expected arrival time at Tehachapi, they called the Federal Aviation Administration (FAA) and an ALNOT (alert notification) was issued at 1900. Family members reported that the pilot had been at his second home, and that the day of the accident he was flying back to Tehachapi. The pilot was dropped off at Santa Ynez airport about 1620; the flight normally takes about 35 to 40 minutes. According to his family, his normal procedure was to check in before he departed and upon his arrival at his destination airport. PERSONNEL INFORMATION The pilot, age 64, held a private pilot certificate with rating for airplane single-engine land, and a third-class medical issued on February 22, 2010. It held the limitation that he must wear corrective lenses. The pilot reported on his most recent application for a medical certificate, that he had a total time of 1,600 hours with 40 hours accrued in the past 6 months. The National Transportation Safety Board (NTSB) investigator-in-charge (IIC) obtained the pilot's personal flight logbook and other paperwork with flight time recorded on it. There were no total hours recorded in the pilot's logbook. The logbook's last entry was dated May 15, 2010, and he recorded his total time as 1.7 hours. The pilot's last flight review had also been recorded on May 15, 2010. The pilot's last recorded flight time for the other paperwork was for March 2002. There was no other paperwork identified as the pilot's logbook. AIRCRAFT INFORMATION The two-seat, low-wing, tail-wheel equipped airplane, N851LT, serial number 851, was manufactured in 1974. It was powered by a Lycoming O-360-A1A 180-hp engine and equipped with a Sensenich model 76EM-8-85 fixed-pitch propeller. According to a logbook entry, the airplane had undergone an inspection under the scope and detail of appendix D Part 43 on April 8, 2011, at an airframe total time of 2,652.5 hours. A total time 1,714.5 hours had been recorded in both the engine and propeller logbooks at the time of the April 8, 2011, inspection. The fuel receipt from Tehachapi Airport indicated that the airplane was fueled on June 17, 2011. There were no records of the airplane being refueled at Santa Ynez Airport from June 16 thru June 19, 2011. METEOROLOGICAL INFORMATION The closest official weather observation station was TSP, which was 13 nautical miles (nm) southwest of the accident site. The elevation of the weather observation station was 4,001 feet mean sea level (msl). An aviation routine weather report (METAR) issued at 1655 PDT, reported wind from 310 degrees at 15 knots, visibility 9 statute miles, clear skies, temperature 23 degrees Celsius, dew point 10 degrees Celsius, and altimeter 29.90 inches of mercury. The recorded METAR at 1715 for TSP reported wind from 310 degrees at 14 knots gusting to 20 knots, visibility 10 statute miles, clear skies, temperature 23 degrees Celsius, dew point 10 degrees Celsius, and altimeter setting 29.20 inches of mercury. WRECKAGE AND IMPACT INFORMATION The accident site was located by a local resident who was driving home about 2030. The resident stated that debris was on the road (a portion of the door and some Plexi-glass), which caused him to stop. He got out of his car, and looked over the edge of the mountain spotting the wreckage. The resident then called the Stallion Springs Police Department. The IIC, and operations and airworthiness inspectors from the FAA, responded to the accident site the following day. The entire airplane came to rest on the west face of a 45-degree slope about 200 feet below the ridgeline of the 4,400-foot mountain. The wreckage was positioned upright. The airplane exhibited leading to trailing edge crush of the entire fuselage relative to the terrain. The propeller assembly separated from the engine crankshaft, and was embedded in the hard dirt about 20 feet below the main wreckage. The accident site was about 13 miles from Tehachapi airport. MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination was conducted by the Kern County Sheriff-Coroner Division, Bakersfield, California. The cause of death was reported as multiple blunt force injuries. The toxicology report presented positive results for: Ethanol 22 mg/DL in cavity blood, Blood Alcohol Concentration 0.022 cavity blood The report indicated that there was low-level alcohol detected in the pilot's system and may be due to decompositional changes. Additional positive toxicology results for Ibuprofen, theobromine, and caffeine were noted. Along with: Donepezil 60 ng/mL in cavity blood Doxylamine 410 ng/mL in cavity blood Donepezil is a cholinesterase inhibitor used orally to treat symptoms of mild-to-moderate dementia of the Alzheimer's type. The elimination half-life of the drug is about 70 hours. Common adverse effects at therapeutic doses can include dizziness and insomnia. Doxylamine is an antihistamine with sedative effects and is sometimes used in the short-term relief of insomnia. The elimination half-life, in therapeutic levels is about 10 hours. The FAA's Civil Aerospace Medical Institute performed forensic toxicology on specimens from the pilot. There were negative results for carbon monoxide and cyanide. The toxicology reported that there was putrefaction of the specimens. The toxicology test findings revealed positive results for tested volatiles: 20 (mg/dL, mg/hg) ethanol detected in blood (cavity) No ethanol detected in kidney 2 (mg/dL, mg/hg) N-Propanol detected in blood (cavity) The toxicology test findings further revealed positive results for tested drugs: Donepezil detected in liver Donepezil detected in blood (cavity) Doxylamine detected in liver 0.559 (ug/ml, ug/g) Doxylamine detected in blood (cavity) Metoprolol detected in liver Metoprolol detected in blood (cavity) The pilot's medical records were reviewed by the NTSB's Chief Medical Officer. The doctor reported that the pilot had reported hypertension, high cholesterol, and heartburn to the FAA for the past 8 years. In 2003, the pilot was diagnosed with Type 2 diabetes and treated with a series of medications. However, the diagnosis of diabetes and its treatment were not reported to the FAA by the pilot or the pilot's physician. Approximately 6 months before the airplane accident, the pilot and his wife reported a significant behavioral change to the pilot's endocrinologist; also reported to his endocrinologist was a recent motor vehicle accident, where the pilot had been driving and struck a parked car. Further medical evaluation and consultation were prescribed; no records of those consultations were identified. The pilot's autopsy report identified significant heart disease, which included wall thickening and two areas in major coronary arteries with more than 75 percent stenosis. Evaluation of the toxicology results by the doctor revealed ethanol, n-propanol, metoprolol (prescribed to treat the pilot's hypertension), donepezil (used to treat dementia of the Alzheimer's type), doxylamine (sedating antihistamine) as well as ibuprofen, caffeine, and theobromate. A detailed report is attached to the public docket for this accident. TEST AND RESEARCH Investigators from the NTSB, FAA, and the airplane builder examined the wreckage at Aircraft Recovery Service, Littlerock, California, on June 22, 2011. Due to the severity of the crush damage, flight control continuity could not be established. However, all the major components, cables, and hardware attachments and fittings were established with no discrepancies noted. The engine examination revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The crankshaft/propeller flange was bent and as a result, the engine could not be manually rotated. The engine was borescoped with no internal damage identified. The top spark plugs were removed and according to the Champion Aviation Check-A-Plug chart AV-27, the spark plugs were normal in appearance. The fuel selector was positioned to the main fuel tank; the fuel tanks were about half full. The oil filter was opened and the oil filter showed no foreign debris. Both magnetos separated from their respective mounting pads; inspection of the magnetos was unremarkable. The propeller blades were labeled A and B. Both propeller blades showed chord wise scratching the length of the blades. Blade A exhibited aft bending about mid-span of the blade. Blade B exhibited aft bending about mid-span of the blade, as well as, leading and trailing edge nicks and gouges. A Vision Microsystems unit and an II Morrow Apollo altitude encoder were shipped to the vehicle recorder division of the NTSB for further evaluation. According to the vehicle recorder specialist, the Vision Microsystem unit had a battery backup SRAM device. The data was successfully downloaded; however, there were no track and engine logs recorded. The II Morrow Apollo altitude encoder had no stored data. ADDITIONAL DATA According to the FAA, the airplane was a VFR flight following flight. Los Angeles Air Traffic Control Center (ZLA) had been in contact with the pilot. At 1711, the pilot was transferred to another ZLA; and at 1716, services were terminated and there was no further contact with the accident pilot. A Transportation Safety Specialist from the National Transportation Safety Board (NTSB) reviewed the radar data from Los Angeles Center for the accident time. According to data, a 2054 discrete transponder code was identified in the area of Lake Cachuma, about 7.21 miles south east of Santa Ynez. The flight track identified a normal flight path from Santa Ynez over the mountains and down into the valley. The flight track showed a steady altitude gain to about 9,500 feet and a straight line. After crossing the mountain range, the flight track remained straight with a gradual descent; about 700-900 feet per minute. The last identified radar return was at 1627, at an altitude of 5,400 feet, and about 15 miles west of the accident site. According to the U.S. Naval Observatory Sun and moon Data for One Day, on the day of the accident, the official sunset was recorded at 2011.
The pilot’s failure to maintain clearance from mountainous terrain during cruise flight, which resulted from his impairment or incapacitation due to multiple medical conditions and sedating medication.
Source: NTSB Aviation Accident Database
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