WPR11FA090

The pilot's loss of control while maneuvering to land, most likely due to spatial disorientation.

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 perce