Chester, CA, USA
N5866S
BEECH S35
The 76-year-old private pilot departed during the hours of darkness on a return trip to his home airport. Radar data revealed a flight track consistent with the pilot hand flying the airplane without the assistance of an autopilot at altitudes appropriate for the terrain elevation. No radar data was available for the approach segments and accident sequence of the flight. Based on witness reports, the airplane appeared to perform a normal crosswind approach over a town and toward the airport runway. During the airport approach, the pilot made a normal radio call and did not appear to be in distress. As the airplane rounded the turn from crosswind to downwind, it continued in a shallow, high-speed descent, directly into the frozen surface of a lake adjacent to the runway. The debris field was on a heading which approximated the downwind segment of the landing runway. The debris field length was consistent with a high-speed, right-wing-low, gradual descent into the ground. The landing gear and flaps were not in the landing configuration, and the speed brakes were not deployed. All sections of the airplane were located at the accident site, and no anomalies were noted with the airframe or engine that would have precluded normal operation. The damage to the propeller was consistent with the engine producing power at the time of impact. The airport was located on the outskirts of a town, adjacent to a lake and a sparsely populated national park. The moon, which exhibited a 6 percent visible disk, would have provided limited illumination and would have been located low on the horizon and behind the airplane during the crosswind and downwind turns. The pilot's forward view would also have been dominated by a dark void as the airplane passed over the town, and began the landing approach. The pilot did not possess an instrument rating, which, coupled with the lighting conditions, could have made him vulnerable to spatial disorientation. Additionally, the airplane's impact trajectory was consistent with him encountering this phenomena. The pilot had experienced a mild heart attack 6 years prior to the accident, with placement of stents in two coronary arteries, and a diagnosis of diabetes. He had denied any medical history in applications for FAA medical certificates. It was not possible to conclusively determine what role, if any, the pilot’s unreported medical conditions played in the accident.
HISTORY OF FLIGHT On January 6, 2011, about 1845 Pacific standard time (PST), a Beech S35, N5866S, impacted the frozen shoreline of a lake adjacent to Rogers Field Airport (O05), Chester, California. The pilot/owner was operating the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The certificated private pilot and passenger were killed. The airplane sustained substantial damage to both wings and the entire fuselage forward of the tailcone. The cross-country personal flight departed Charles M. Schulz-Sonoma County Airport (STS), Santa Rosa, California, about 1745. Visual night meteorological conditions prevailed, and no flight plan had been filed. At the time of the accident a witness, who was a neighbor of the pilot, was positioned in the kitchen of his residence, which was located about 4,500 feet northeast of the departure end of runway 34 at Chester Airport. The location approximated the beginning of the right downwind leg for that runway. The house was surrounded by 70-foot-tall pine trees, with kitchen doors that opened to a north-facing deck. The witness reported that his radio scanner was on, and he heard a faint radio call from the pilot over the common traffic advisory frequency (CTAF), reporting that he was inbound for landing. A few minutes later he heard the pilot clearly report that he was overflying the airport, with the intention of entering the right base for runway 34. The pilot then transmitted, "Thanks Vic for turning the lights on!" The witness explained that the pilot knew he was listening on scanner, and usually makes the call in jest as he approaches the airport. The witness then opened his kitchen door, and walked onto the deck in an effort to observe the airplane. He was facing north, and could hear the sound of an airplane to his left. The sound continued to travel in front of him from left to right. He stated that this was consistent with the normal sound that he would often hear as aircraft joined the traffic pattern. He could not see the airplane, but explained that this was not unusual due to the trees. The sound continued to pass to his right, and towards the south. He reported that the sound of the airplane was unremarkable, with no indication of distress. He then went inside, and continued to listen to his scanner; he heard no more radio transmissions. He stated that this was unusual because the pilot usually transmits a position report as he approaches the right base, followed by a final report after he clears the runway. About 5 minutes later, the witness heard radio transmissions of emergency personnel responding to the report of an airplane accident. A second witness was walking her dogs along First Avenue, which is located between the airport and Lake Almanor parallel to, and east of, runway 34. The witness was located at the southern end of the avenue, about 1,900 feet northeast of the runway 34 threshold. Seventy-foot-tall trees lined the road to her east and west, leaving an unobstructed view both along the avenue back to the north, and through a clearing towards the southwest. She heard an airplane to the southwest, and observed lights flying over the airport in a northbound direction. She stated that the engine sound was normal and appropriate, and she thought nothing more of it. A short time later she heard an airplane to the north, but this time the engine was much louder, with a sound she described as, "full-bore, pinning it." Looking to the north, she then observed red, green, and white lights fly from left to right in a gradual descent. The lights descended behind trees, and towards the lake. She then heard the sound of a thud, followed by the noise of cracking ice. The Federal Aviation Administration (FAA) provided radar data for the flight. The data revealed a target at 1551, displaying a 6313 beacon code, about 12 miles northeast of Sonoma County Airport. The target indicated a mode C altitude of 4,900 feet, and continued on a meandering northeast track for the next 45 minutes and 100 miles, while incrementally climbing to 11,100 feet. The final radar return occurred a few seconds later, at an altitude of 11,000 feet, about 18 miles southwest of the accident location. The airplane flew above 10,000 feet for about 31 minutes while under radar surveillance. The highest obstacle elevation along the airplane's route of flight was Spring Valley Mountain, the peak of which was at an elevation of 6,859 feet. PERSONNEL INFORMATION A review of FAA airman records revealed that the 76-year-old pilot held a private pilot certificate with ratings for airplane single-engine land. The pilot did not possess an instrument rating. The pilot held a third-class medical certificate issued on April 21, 2009, with limitations that he must wear corrective lenses. A set of damaged spectacles were located within the cabin area. An examination of the pilot's logbook indicated an estimated total flight time of about 2,700 hours as of February 19, 2010, about 600 hours of which were flown at night. A set of loose pages within the logbook indicated that during the period between the last logbook entry and December 1, 2010, the pilot had flown 23 flights, the duration of which had not been documented. The pilot had amassed about 467 flight hours during the period between June 2001 and the accident, the majority of which occurred in the accident airplane, while based at Chester Airport. The flight logs indicated that during the 90-day period prior to the accident, the pilot had performed a total of two night takeoffs and landings. During the period from September 22, 2010, to November 6, 2010, he had performed a total of eight night takeoffs and landings, with all landings occurring at the accident airport. Federal Aviation Administration Regulation, Part 61.57, states, in part, that no person may act as a pilot-in-command of an aircraft carrying passengers during the period beginning 1 hour after sunset and ending 1 hour before sunrise, unless within the preceding 90 days that person has made at least three takeoffs and three landings to a full stop during the period beginning 1 hour after sunset and ending 1 hour before sunrise. AIRCRAFT INFORMATION The low-wing, retractable-gear airplane, was manufactured in 1965. It was powered by a six-cylinder, fuel injected Teledyne Continental Motors (TCM), IO-520-BA (3) engine, serial number 814453-R, and equipped with a three blade aluminum Hartzell constant-speed propeller. The maintenance logbooks revealed that the airframe, engine, and propeller last received an annual inspection on December 6, 2010, at a total airframe time of 3,217 flight hours, 5 flight hours prior to the accident. At the time of the accident, the engine had accumulated 477 flight hours since its last major overhaul, which occurred in February 2000. The airplane was equipped with attitude, direction, and navigation instruments required for flight in instrument meteorological conditions, and the original factory equipped autopilot. The airplane was not equipped with a supplemental oxygen system. METEOROLOGICAL INFORMATION A remote automated weather station (RAWS) was located in Westwood, California, about 10 miles east of the accident site at an elevation of 4,994 feet. An automated weather observation was issued about 2 minutes after the accident. It reported calm winds; a temperature of minus 2 degrees C; dew point minus 6 degrees C; and an altimeter setting at 30.25 inches of mercury. Local fire and law enforcement officers, who located the airplane shortly after the accident, reported calm winds, clear skies, and unlimited visibility at the time of their arrival. They did not observe the presence of the moon. According to the U.S. Naval Observatory, Astronomical Applications Department, the computed sunset occurred in Chester, at 1654, with civil twilight ending at 1724. There was a waxing crescent moon, with 6 percent of its visible disk illuminated. Moon transit occurred at 1408, and moonset occurred at 1936 at an azimuth of 254 degrees. WRECKAGE AND IMPACT INFORMATION The accident site elevation was 4,500 feet mean sea level (msl), and was located about 3,500 feet northeast of the approach end of runway 34 at Chester Airport, on the frozen shallows of the western shore of Lake Almanor. The airport was situated on the southern outskirts of Chester, adjacent to the west side of the lake, at an elevation of 4,528 feet msl. The lake was about 12 miles long, and about 3 miles wide at the area of the accident site. The banks of the lake beyond Chester, and the area surrounding both it and the town were sparsely populated, and within the confines of Lassen National Forest. The debris field spanned a distance of about 900 feet, on a bearing of 160 degrees magnetic, parallel to runway 34. The first identified point of impact was characterized by a 12-inch-deep, 7-foot-long, teardrop-shaped swath of excavated snow. The ground excavation was oriented on a bearing of about 150 degrees. A second swath was located about 15 feet beyond the initial impact. The swath continued 40 feet further expanding to about 20 feet in width, and exposing the mud surface of the lakeshore. A single separated propeller blade was located within the initial ground scar, and the odor of aviation gasoline was present. The blade appeared bent aft in an s-shape, and exhibited chordwise abrasions, and leading edge gouges. The remaining two blades and the propeller hub were located, along with the right wing tip, about 40 feet beyond the first blade. Both blades remained firmly attached to the hub and exhibited trailing edge wrinkling. The propeller flange remained attached to the hub, and had separated from the crankshaft just forward of the engine case. The crankshaft fracture surface exhibited torsional granular features, on a 45-degree conical plane around its circumference. The debris field expanded for another 100 feet, and appeared enveloped with an oily residue. The oily area contained fragmented sections of the right wing, with its associated flap and aileron, clear plastic material, and the engine cowling. The left wing was located 150 feet further downrange, had become separated at the wing root, and exhibited upward curling damage midspan. The debris field continued 500 feet further, and contained the right main landing gear, cabin door, fragments of engine accessories, the control yoke, and various cabin items. The main fuselage came to rest 700 feet beyond the initial impact point on a heading of about 020 degrees. The entire cabin, forward of the aft seats, had sustained crush damage through to cockpit controls, instrument panel and firewall, which had become canted 90 degrees to the left. The airspeed indicator displayed a speed of 182 knots. The tailcone and empennage sections remained attached, and were largely undamaged. The engine was the last component located along the debris field, coming to rest 200 feet beyond the fuselage. Both the left and right forward seats were separated from their seat tracks, and were located midway between the fuselage and engine. The fuel selector valve/strainer assembly was located within the crushed cabin area. Examination of the strainer revealed residual quantities of a fluid within the chamber, the odor of which was consistent with aviation gasoline. The fluid was tested with SAR-GEL water indicating paste, and no water was present. All major sections of the airplane were accounted for at the accident site, and no indications of pre or post impact fire were observed. The positions of occupants relative to the airplane structure were consistent with the pilot being located in the left forward seat, and the passenger in the right seat. The airplane was equipped with a single arm, throw-over type yoke control installation, which appeared set to the left-side position. MEDICAL AND PATHOLOGICAL INFORMATION The pilot’s two most recent applications for a third-class Airman Medical Certificate, dated 5/1/2007 and 4/21/2009, indicated "No" in response to "Do You Currently Use Any Medication," and to all items under "Medical History," including specifically "Heart or vascular trouble," "Diabetes," "Admission to hospital," and "Other illness, disability, or surgery." Personal medical records noted a history of "mild heart attack" in October 2005, treatment for high cholesterol since that time, and a diagnosis of diabetes in November 2005. The personal medical records did not note any cardiology visits or cardiac symptoms since 2005. The report of autopsy performed on the pilot for the Plumas County (California) Sheriff/Coroner noted the cause of death as the result of multiple blunt force injuries. The report further stated that the heart weighed 500 grams and that, "The coronary arteries arise normally and follow the usual distribution of a right dominant pattern with severe calcified atherosclerotic stenosis. The left anterior descending coronary artery has a stent present in the proximal and mid sections. The first branch of the left anterior descending coronary artery has also stents present in it. The right coronary artery is about 20% to 30% narrowed by the calcified atherosclerotic plaque in its mid section. The circumflex coronary artery is 80% to 90% narrowed by the atherosclerotic plaque in its mid section. The chambers and valves bear the usual size and position relationship and are unremarkable. The right ventricular wall is 0.3 cm and the left is 1.9 cm in thickness. The myocardium is dark red-brown, firm and unremarkable; the atrial and ventricular septa are intact. The aorta and its major branches arise normally and follow the usual course with severe atherosclerosis. The vena cava and its major tributaries return to the heart in the usual distribution and are within normal limits." Toxicological tests on specimens from the pilot were performed by the FAA Civil Aeromedical Institute. 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. TESTS AND RESEARCH Engine The NTSB investigator-in-charge (IIC) and a TCM representative examined the engine at the accident site. The engine came to rest inverted, and had become separated from its engine mounts. The alternator, starter, fuel pump, fuel control with throttle body, right muffler, and induction manifold assembly had become liberated from the engine, and were located within the debris field. The forward crankcase sustained crush damage, exposing the forward gear assemblies. The gears appeared oil wetted, and free of damage. The throttle body sustained impact damage and had become separated from the engine. The throttle valve appeared in the full open position. The throttle, mixture, and governor controls had sustained varying degrees of fragmentations, and were accounted for at their respective engine controls. All cylinder heads except number three had sustained varying degrees of crush damage to their cooling fins and rocker covers. The rocker covers were removed, revealing all the valves to be wet with oil and free of distress. The spark plug electrodes were light gray in color, with light gray deposits. The vacuum pump remained undamaged, and was removed from the engine to facilitate the rotation of the crankshaft. Rotation of the pump drive shaft by hand resulted in smooth and unrestricted movement. Disassembly of the pump revealed the four vacuum blades to be intact. The splined shaft remained attached to the rotor, and no evidence of catastrophic malfunction was noted. Rotation of the crankshaft by hand utilizing the vacuum pump drive gear resulted in smooth and free movement. Thumb compression was obtained for all cylinders, and all valves exhibited similar amounts of lift. Gear train continuity was confirmed through to the accessory case and forward gear assemblies. The magnetos remained firmly attached to their mounting pads and rotation of the crankshaft resulted in a spark at each magneto lead output. Left Wing The left wing remained largely intact, with both the aileron, flap, and main landing
The pilot's loss of control while maneuvering to land, most likely due to spatial disorientation.
Source: NTSB Aviation Accident Database
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