BEAR VALLEY, CA, USA
N6831U
Mooney M20D
About noon, during a cross-country flight under benign visual meteorological conditions, the pilot lost control of her airplane. It entered an uncontrolled descent and impacted 9,200-foot mean sea level terrain in a nearly vertical nose down attitude. The wreckage was not located for several days. The pilot had about 1,700 total hours of flight time, of which about 1,600 hours were in the accident model of airplane. She was a current pilot. The airplane was not equipped with an autopilot or any wing-leveling device. There were no en route communications between the pilot and any FAA facility. No evidence of any mechanical malfunction with the airframe or engine was noted during the on-scene wreckage examination. The continuity of the airplane's flight control system was confirmed. Three witnesses who observed the pilot prior to departure indicated that she did not appear physically well. One of the witnesses stated the pilot had a 'flushed' look on her face and bags under her eyes. The second witness reported that the pilot 'did not look normal.' The third witness stated that the pilot 'did not look well.' The toxicological examination revealed the presence of a readily available over-the-counter decongestant in body tissue; however, no blood level for the drug was ascertained. The drug's involvement remains undetermined.
HISTORY OF FLIGHT On September 2, 1999, between 1138 and 1245 hours Pacific daylight time, a Mooney M20D, N6831U, owned and operated by the pilot, descended into mountainous terrain about 10 nautical miles east-northeast of Bear Valley, California. Visual meteorological conditions prevailed during the personal flight, and no flight plan was filed. The flight was conducted under the provisions of 14 CFR Part 91. The airplane was destroyed, and the commercial pilot was fatally injured. The flight originated from Corona, California, between 0930 and 1000. Family members reported that the pilot planned to fly from the uncontrolled Corona Municipal Airport, where the airplane was based, to the Fallon, Nevada, Municipal Airport in order to attend a wedding. The pilot's departure time was approximated and was based, in part, upon the pilot's receipt of a weather briefing at 0847 from the Federal Aviation Administration (FAA), and a fuel receipt time stamped 0915. The pilot's route of flight was not determined, and no FAA en route services were provided to the pilot. No witnesses reported observing the accident. On September 4, 1999, the Civil Air Patrol located the accident site in the Sierra Nevada Mountains, about 80 nmi south-southwest of Fallon. The wreckage was located above the tree line, in the Stanislaus National Forest. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with an instrument rating. No current flight record logbook was located in the wreckage. Previous logbooks terminated with flights performed prior to August 1996. The pilot's last biennial flight review was accomplished in the accident airplane on December 31, 1997. The flight times listed for the pilot in the Safety Board's Factual Report were estimated. They were based upon a combination of data listed in the airplane maintenance records, logbook entries, and the pilot's daily planner. The pilot's estimated total flight time (experience) is 1,700 hours. Her estimated total flight time piloting a Mooney is about 1,600 hours. A review of entries listed in the pilot's daily planner indicated that between August 1998 and the accident date, the pilot had flown her airplane about 33 hours. During the 90-day period preceding the accident, the pilot had flown her airplane about 15 hours. AIRCRAFT INFORMATION Mooney Aircraft Company personnel reported that the airplane was manufactured in 1963. Its manufacture predated factory installation of the "Positive Control System," and the wing-leveling system was not subsequently added. In March 1964, retractable landing gear was installed. The airplane was not equipped with an autopilot. A review of logbook entries, in conjunction with a verbal statement made by the mechanic who certified that he had inspected the airplane pursuant to the Federal Aviation Administration's annual inspection requirements, indicated that the pilot had routinely performed maintenance on her airplane. (See the logbook entries appended to this report). No airplane or engine times were observed recorded in the logbooks for the last annual inspection that was listed as having been performed on December 1, 1998. Also, no airplane time was listed for the subsequent owner-performed maintenance involving an overhaul of the brake master cylinder on August 15, 1999. The 26 hours listed in the Safety Board's Factual Report form representing the time since accomplishment of the last annual inspection was estimated. It was based upon entries listed in the pilot's daily planner that was found in the wreckage. METEOROLOGICAL INFORMATION The Lake Tahoe Airport, elevation 6,264 feet mean sea level, is the closest aviation weather observation station to the accident site. It is located about 27 miles north-northwest of the accident site. In pertinent part, at 1147, Lake Tahoe reported its surface visibility was 7 miles, and scattered clouds were present with bases about 8,000 feet above ground level. COMMUNICATION A search of nearby FAA facilities found no evidence of any air-to-ground communications or services provided to N6831U on September 2, 1999, between 1100 and 1300. According to the FAA, during this time interval it was unable to establish a track for the airplane on radar. WRECKAGE AND IMPACT INFORMATION The National Transportation Safety Board's on-scene investigation revealed the airplane impacted estimated 10-degree upsloping terrain at an elevation of about 9,200 feet mean sea level. The global positioning satellite (GPS) coordinates for the accident site are 38 degrees 27.27 minutes north latitude, by 119 degrees 49.39 minutes west longitude. The entire airplane was found in a near vertical nose down pitch attitude in a 3- to 6-inch-deep impact crater in the rocky terrain. No evidence was located of any other (secondary) crater or tree/ground scar impact signature. The airplane was found oriented on a magnetic bearing of about 165 degrees. It was resting on top of the impact crater, which had dimensions matching the size and shape of the wings and engine. Fragments of red and green lens fragments were observed in the crater beneath the approximate location of the destroyed left and right wing tips. The leading edges of both wings were observed symmetrically accordioned in an aft direction, with the compressive buckling extending from the leading to trailing edges. The crush line appeared to be nearly perpendicular to the wing chord. The landing gear and flaps were observed in the retracted position. The baggage door's locking pin was found in the extended (locked) position. The buckling of fuselage structure adjacent to the door matched the deformation observed in the door. All of the flight control surfaces were found with the main wreckage, and all were observed attached to their respective hinges, with the exception of the left elevator's inboard hinge and the right aileron, which was observed beneath the wreckage. The tail was found bent about 90 degrees upward. The continuity of the flight control push-pull tubes between the aft cabin area and the tail was established. All counterweights were found with the wreckage. The emergency locator transmitter (ELT), cockpit, instrument panel, engine, and propeller assembly were destroyed. An odor of fuel was noted in the ground beneath the wreckage. The propeller was found sheared off of the crankshaft at its mounting flange. The blades were observed torsionally deformed and gouges were apparent in the leading edges. The blades were scratched in a chordwise direction. Both of the blade tips were broken off. The engine oil sump and the carburetor were observed in an impact-damaged area of the wreckage and were destroyed. The oil pressure screen was observed clear. The crankshaft could not be rotated. There was no evidence of fire or streams of oil along the fuselage. The top spark plugs were removed from the engine and they exhibited a light gray color consistent with Champion's "Check-a-Plug" chart AV-27 indicating normal operation. The rocker box covers were removed and the rockers, valves, springs, and keepers were observed intact. The exhaust stacks and heater shroud were found crushed flat. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed by the Alpine County Sheriff-Coroner's Office, P.O. Box 278, Markleeville, California 96120. The FAA's Civil Aeromedical Institute (CAMI) performed toxicology tests on specimens from the pilot. The test results revealed pseudoephedrine and phenylpropanolamine in the pilot's kidney and lung. Ethanol and acetaldehyde were detected in kidney and muscle. CAMI reported that the maximum value of ethanol detected in any of the tested specimens was noted in the muscle, at a value of 27 mg/dl. No blood was available for testing. No other drugs were detected. See CAMI's toxicology report for additional information. According to pharmacological reference material, pseudoephedrine is a drug commonly used as a decongestant in over-the-counter medications. Three acquaintances of the pilot observed her on the morning of the accident. One witness stated that the pilot had a "flushed" look on her face and bags under her eyes. The second witness reported that the pilot "did not look normal," and said she was quieter than normal and was not her vibrant self. The third witness stated that the pilot "did not look well." TESTS AND RESEARCH The pilot's route of flight between the departure airport and the accident site was not determined; no flight plan was filed. Based upon the known locations of these points, the Safety Board investigator calculated that the pilot's airplane was capable of cruising between 120 and 140 knots over the projected 300 to 330 nautical mile course. The investigator calculated that the pilot's en route arrival time at the accident site could have been between 1138 and 1245. For the purpose of data entry, the mid-interval of 1212 was used in this report to represent a possible accident time. ADDITIONAL INFORMATION The airplane wreckage was released to the pilot's assigned insurance adjuster on September 30, 1999. No parts or records were retained.
The pilot's in-flight loss of control for undetermined reasons.
Source: NTSB Aviation Accident Database
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