WPR16FA042

The pilot's loss of control due to spatial disorientation while maneuvering during an instrument approach in instrument meteorological conditions.

The instrument-rated private pilot was operating the airplane on an instrument flight rules flight in instrument meteorological conditions (IMC). As the airplane neared the destination airport, the controller cleared the pilot for the instrument landing system (ILS) approach, instructed him to descend to 3,400 ft mean sea level (msl), and provided him with a heading to intercept the localizer course. The pilot acknowledged the clearance and began descending the airplane, but did not initiate the turn. About 30 seconds later, the controller again instructed the pilot to turn to intercept the localizer course. The pilot complied, turned west, and began tracking toward the airport south of the localizer course. The controller asked the pilot whether the airplane was established on the localizer, to which the pilot replied, "I'm re-establishing." Shortly thereafter, the controller asked the pilot if he was receiving the glideslope indication for the approach. The pilot confirmed that he was receiving the glideslope, but stated that he was "off glideslope" and "too high." However, at this time, the airplane was 800 ft below the minimum altitude for that segment of the approach (3,400 ft msl). The controller issued a low altitude alert, cancelled the approach clearance, and instructed the pilot to turn north and climb. The pilot acknowledged; however, the airplane turned south and did not climb. The controller again issued the pilot instructions to turn and climb, and the airplane began to turn north and climb before subsequently entering a descent. Shortly thereafter, the pilot stated, "I'm losing it." No further transmissions were received from the pilot, and radar contact was lost in the vicinity of the accident site. The airplane impacted heavily-wooded terrain about 12 nautical miles southeast of the destination airport, at an elevation about 1,400 ft. Postaccident examination of the airplane revealed heavy fragmentation consistent with a high-energy impact as well as evidence of a postimpact fire. Examination of the airframe, flight controls, and the engine revealed no evidence of any preimpact mechanical failures or anomalies. Although the extensive damage precluded examination of the primary vacuum pump and functional testing of the autopilot system, it is unlikely these components malfunctioned because before beginning the approach, the pilot experienced no difficulty complying with air traffic control-assigned altitudes and headings, and, throughout the flight, he gave no indication that he was experiencing problems with the flight controls, flight instruments, or autopilot. Based on weather data and the pilot's radio communication that he was "in the weather," the airplane was operating in IMC throughout the approach. When issued instructions to execute a missed approach, the pilot experienced a high workload that involved changes to the airplane's heading, altitude, and likely, configuration; this situation was conducive to the development of spatial disorientation. The pilot likely recognized the onset of spatial disorientation as evidenced by his statement to the controller, "I'm losing it;" however, the pilot was unable to make the appropriate corrective inputs before losing control of the airplane.

Fuel Pump Diaphragm The fuel pump diaphragm was examined at the NTSB Materials Laboratory. Scanning electron microscope imagery of the tear in the diaphragm revealed signatures consistent with tensile overstress as a result of impact forces. Spatial Disorientation The FAA Civil Aeromedical Institute's publication, "Introduction to Aviation Physiology," defines spatial disorientation as a loss of proper bearings or a state of mental confusion as to position, location, or movement relative to the position of the earth. Factors contributing to spatial disorientation include changes in acceleration, flight in IMC, frequent transfer between visual meteorological conditions (VMC) and IMC, and unperceived changes in aircraft attitude. The publication states that pilots flying in IMC are more susceptible than usual to the stresses of flight, such as fatigue and anxiety, and any event that produces an emotional upset is likely to disrupt the pilot's mental processes, making them more vulnerable to illusions and false sensations. The FAA's Airplane Flying Handbook (FAA-H-8083-3A) describes some hazards associated with flying when the ground or horizon are obscured. The handbook states, in part: "The vestibular sense (motion sensing by the inner ear) in particular tends to confuse the pilot. Because of inertia, the sensory areas of the inner ear cannot detect slight changes in the attitude of the airplane, nor can they accurately sense attitude changes that occur at a uniform rate over a period of time. On the other hand, false sensations are often generated; leading the pilot to believe the attitude of the airplane has changed when in fact, it has not. These false sensations result in the pilot experiencing spatial disorientation." The Alameda County Sheriff's Office Coroner's Bureau, Oakland, California, performed an autopsy on the pilot. The cause of death was listed as blunt force trauma. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing; tests were negative for ethanol and all tested-for drugs. Carbon monoxide testing could not be performed with the samples available. The 1126 automated weather observation at Livermore Municipal Airport (LVK), Livermore, California, located about 8 miles east of the accident site, included wind from 260° at 15 knots, 10 miles visibility, broken cloud layers at 1,300 and 3,200 ft, temperature 15°C, dew point 12°C, and an altimeter setting of 29.82 inches of mercury. The 1154 automated weather observation at Hayward Executive Airport (HWD), Hayward, California, located about 7 miles west of the accident site, included wind from 270° at 11 knots, 9 miles visibility, broken ceiling at 3,900 ft, overcast ceiling at 5,000 ft, temperature 14°C, dew point 12°C, and an altimeter setting of 29.85 inches of mercury. A weather computer model balloon sounding for the accident site about 1100 showed clouds likely from the surface through 6,000 ft msl, with drizzle and light rain. Weather satellite information about the time of the accident showed clouds over the area of the accident site moving northwest to southeast. Weather radar animation for the area of the accident site at the time of the accident showed light precipitation. The area forecast, issued at 0345 and valid through the time of the accident, included overcast ceilings at 1,000 ft above ground level (agl) and visibilities of 3 to 5 miles in light rain and mist. AIRMET advisories issued between 0645 and 0730, valid for the time of the accident, warned of moderate turbulence below 18,000 ft msl, IMC due to precipitation and mist, and mountain obscuration. Instrument conditions were forecast to improve between 1000 and 1300; however, the mountain obscuration conditions were forecast to continue beyond 1300. The pilot held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. He held an FAA third-class medical certificate, which was issued in August 2015 with a limitation requiring the use of corrective lenses. Review of the pilot's logbook indicated that he had accumulated about 1,262 total hours of flight experience, of which about 960 hours were in the accident airplane make and model. The pilot had accumulated about 43 total hours of actual instrument flight experience, 3.5 hours of which were in the 6 months before the accident, and about 82 hours of simulated instrument experience. His most recent flight review and instrument proficiency check were conducted on November 21, 2015. The accident site was located on a heavily-wooded hillside about 12 nautical miles southeast of OAK at an elevation about 1,400 ft. The initial impact point was identified by several fallen trees and large branches. From the initial impact point, the wreckage path extended downhill about 300 ft on a magnetic heading about 330°. The cockpit and cabin area was largely consumed by a post-crash fire. The wreckage was recovered to a secure facility for examination due to its heavy fragmentation and the difficult terrain at the accident site. All major components of the airplane were accounted for during reconstruction of the wreckage, and there was no evidence of an inflight breakup. The cabin and cockpit area, including all flight instruments and the autopilot, were destroyed by impact and fire. The left and right aileron control cables remained attached to the control chain. Both stabilator cables remained attached to the lower stabilator t-bar assembly. The left and right rudder control cables remained attached to the rudder control arm assemblies. The left and right wings were separated from the fuselage at their respective roots and displayed varying degrees of impact and fire damage. Neither left nor right wing aileron bellcrank stops exhibited indications of flutter, and all control cable separations exhibited signatures of overstress. The fuel selector was in the left tank position, and the filter was free of contaminants. The fuel system was breached in multiple locations. The landing gear down-locks displayed no damage, consistent with the landing gear having been in a retracted position at the time of impact. Measurement of the wing flap actuator threads corresponded to a flaps-retracted position. The empennage displayed significant impact damage and was separated into several sections. The right side horizontal stabilizer exhibited thermal damage. Both stabilator cables remained attached to the stabilator arm assembly, and the left and right rudder cables remained attached to the rudder bellcrank assembly. The propeller was separated from the engine at the crankshaft flange. All three propeller blades remained attached at the hub and exhibited varying degrees of torsional twisting and s-bending. The propeller governor remained attached at its mounting pad with the pitch control rod securely attached to the control wheel. The governor was removed for examination; the drive was intact and free to rotate, and the gasket screen was free of contamination. The engine was separated from its mounts and displayed significant impact damage to the Nos. 1, 3, and 5 cylinders. The No. 1 cylinder rocker assemblies were absent. The No. 3 cylinder head was impact separated, leaving only the barrel in place. The No. 5 cylinder was completely separated from the engine; the piston remained in place. Due to impact damage, the crankshaft could not be rotated by hand. The spark plugs were removed (except for those from the No. 3 cylinder, which were not located), and all displayed normal wear. The Nos. 2, 4, and 6 cylinder rocker covers were removed, and the rocker boxes displayed no anomalies. The Nos. 2, 4, and 6 cylinder combustion chambers were examined with a borescope and exhibited no anomalies. Holes were drilled through the engine case to facilitate internal examination of the connecting rods, crankshaft, and camshaft, which revealed no eviden