ERA17FA231

The pilot's loss of control due to spatial disorientation while maneuvering in night conditions over an area devoid of ground reference lights.

The noninstrument-rated private pilot departed on a night flight for which he had not received proper authorization from the flight school that owned the airplane. For most of the approximate 30-minute flight, including taxi and takeoff, the pilot was conducting a video call with his girlfriend, but ended the call about 6 minutes before the accident occurred. During the flight, the pilot completed one practice hold pattern, maintaining nearly constant altitude about 1,400 ft mean sea level, then turned right toward an area with no ground reference lights, likely to perform another hold pattern, during which the airplane's altitude began to vary. The airplane then entered a right descending turn, during which it exceeded the standard turn rate, reached a rate of descent about 6,000 ft per minute, and subsequently impacted the ground. The airplane was destroyed by high-energy impact forces. Personnel from the flight school assumed that the airplane had become stuck at a coastal airport due to weather but did not attempt to locate the pilot and did not report the airplane missing until 4 days later. An undetermined malfunction of the airplane's emergency locator transmitter (ELT) likely also contributed to the delay in identifying the crash and locating the wreckage. The wreckage was subsequently located, recovered, and examined; there were no discrepancies with the airframe, flight controls, engine, or recovered engine accessories. The flight instructor who flew in the airplane earlier the day of the accident with the accident pilot later reported that the attitude indicator displayed a "3° or less" right bank during that flight; he did not write up the discrepancy. However, the airplane's directional gyro and attitude indicator displayed a heading and bank angle consistent with the radar data and the disposition of the wreckage path, which suggests an operative vacuum system and functional vacuum-operated flight instruments at the time of the accident. Although debris was found in the vacuum regulating valve, the debris was consistent with material produced by an insect, which likely entered the valve after the accident occurred. Postaccident toxicology testing of specimens from the pilot identified ethanol and n-propanol. It is likely that the n-propanol and some of the ethanol was from postmortem production; however, the investigation was unable to eliminate the possibility that some of the ethanol could have been from ingestion and could not determine whether or to what extent it may have contributed to the accident. Conditions conducive to the development of spatial disorientation were present at the time of the accident, including the night conditions, operating over an area with no ground lighting, scattered clouds (which would have reduced available moon illumination). Additionally, the airplane's spiraling descent and the fragmentation of the wreckage due to high-energy impact are consistent with the known effects of a loss of control due to spatial disorientation.

The Miami-Dade Medical Examiner's Office, Miami, Florida, performed a postmortem examination of the pilot. The cause of death was multiple blunt injuries. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology testing on specimens from the pilot. According to the toxicology report, testing for carbon monoxide and cyanide was not performed. No tested-for drugs were detected in the heart specimen; 79 and 67 mg/dl ethanol were detected in the liver and muscle specimen, respectively, and unquantified amounts of n-propanol were detected in the muscle and liver specimens. The Miami-Dade Medical Examiner's Office toxicology testing was negative for tested drugs; 0.094% and 0.099% ethanol were detected in the right chest blood and bile specimens, respectively. Ethanol is primarily a social drug with a powerful central nervous system depressant. After absorption, ethanol is quickly distributed throughout the body's tissues and fluids fairly uniformly. The distribution pattern parallels the water content and blood supply of each organ. Ethanol and n-propanol may be produced in body tissues after death. The NWS southeast section of the Surface Analysis Chart valid from 2000 EDT (0000Z July 2, 2017) depicted a high-pressure ridge extending over the area with easterly winds of 10 to 15 knots across south Florida associated with the tropical trade winds. No frontal or outflow boundaries associated from any thunderstorms were depicted across the region. A review of the NWS National Composite Radar Mosaic revealed no echoes within 20 miles of the accident site. The TMB Automated Surface Observation System, located about 20 nautical miles (nm) east-northeast of the accident site reported at 2053, wind from 090° at 8 knots, 10 statute miles visibility, scattered clouds at 2,500 ft above ground level, temperature 29°C, dew point 24°C, and an altimeter setting of 30.14 inches of mercury. The Miami 2000 sounding was reviewed and a High Resolution Rapid Refresh (HRRR) numerical model for 2100 over the accident site. The sounding indicated a relative humidity greater than 80%, supporting scattered low clouds between 1,500 and 3,000 ft. The wind profile indicated a surface wind from 100° at 5 knots, with winds from the east with little directional variation with height. The mean 0 to 18,000 ft wind was from 080° at 6 knots. The wind profile did not identify any strong vertical wind shears supporting any significant turbulence below 10,000 ft. At the time of the accident, the sun was more than 15° below the horizon at an azimuth of 300°. The moon was 54° above the horizon at an azimuth of 213°, the phase was a waxing gibbous with 60% of the moon's visible disk illuminated. The pilot, age 29, held a private pilot certificate with a rating for airplane single-engine land, issued April 18, 2017, and held a 1st class FAA medical certificate with no limitations, issued December 1, 2016. According to the operator, the pilot's total flight experience was 136.3 hours, all of which was in the accident airplane make and model. He had accrued 66.6 hours as pilot-in-command, 42 hours in the previous 90 days and 12 hours in the previous 30 days; he had flown 3 hours of night operations, none of which were in the previous 90 days. He had accrued 29.4 hours simulated instrument flight, of which 10.6 hours were in the previous 30 days. The two-place, high-wing airplane, serial number 15281280, was manufactured in 1978. It was powered by a 110-horsepower Lycoming O-235-L2C engine and equipped with a McCauley two-bladed, fixed pitch aluminum propeller. It was also equipped with vacuum-driven gyroscopic flight instruments consisting of an attitude indicator and directional gyro, and an electrically-operated turn coordinator. Dean International, Inc., purchased the airplane on June 15, 2008, and it was used for visual and instrument flight rules flight training. Since purchase, it had accrued about 7,084 hours. The airplane was maintained in accordance with 14 CFR Part 43 Appendix D and inspected every 100 hours and annually. Maintenance records indicated that the airplane's last altimeter, static system, and transponder tests were performed on July 8, 2016, and the last 100-hour inspection was on June 27, 2017. The recorded hour meter reading at the 100-hour inspection was 3,670.5; the hour meter reading at the time of the accident was 3,690.0 hours. The flight instructor who flew with the accident pilot earlier that day initially reported that there were no discrepancies with the engine, engine systems, airplane, or airplane systems during the 1.6 hour flight; however, he later reported that, "while flying, the [attitude indicator] was showing a slight bank to the right of 3 degrees or less." A review of the airplane discrepancy sheets from January 5, 2017, to June 27, 2017, revealed only 1 entry pertaining to an inoperative attitude indicator. The corrective action indicated that the defective indicator was removed and replaced and the system was tested on January 27, 2017. The airplane was then approved for return to service. The airplane impacted marshy terrain about 10 nautical miles west of X51; no ground reference lights were in the surrounding area. The first identified ground scar exhibited a teardrop shape and an energy path oriented on a magnetic heading of 075°. The right main landing gear brake assembly and right wingtip were located on the right side of the energy path, and the nose landing gear was located on the left side of the energy path. Additional components of the airplane were located on both sides of the energy path between the initial impact crater and the main wreckage. No odor of fuel or fuel sheen was noted. The main wreckage was also located about 136 ft and 068° from the first impact location. The fuselage was oriented on a magnetic heading of 194°. The main wreckage consisted of the fuselage, wings, empennage, and engine. All observed and identified components were recovered on July 8 and secured for further examination. Examination of the wreckage following recovery revealed that all structural components and primary and secondary flight controls remained attached or were recovered from the immediate vicinity of the accident site. None of the parts exhibited evidence of pre- or postimpact fire. The cockpit was fragmented. The pilot's seat was separated from the airplane, and the seat lock pin was bent aft. The pilot's lap belt was not latched, and the single shoulder harness was not attached to the lap belt. No stretching was noted to either the lap belt or shoulder harness webbing. Both control wheel tubes (shafts) were separated from the control wheels at the rivets and from the control Y assembly at the universal joints. Only one control wheel was found during the wreckage examination. The control wheel was fractured and separated from the control tube. The leading edges of both wings exhibited full span chordwise crushing. The main spar of the left wing and the aft spar of the right wing were fractured at wing station 84.00; the fracture surfaces exhibited overload failure. Both lift struts remained connected at both ends, and the full spans of both flaps remained attached. Both left and right ailerons were accounted for. Examination of the left wing revealed that the stall vane hose was separated from the stall inlet attach point at the aft side of wing leading edge, and the stall horn was separated from the opposite end of the hose. Examination of the aft fuselage revealed that it was fractured at fuselage station 173.41, about the location of the leading edge of the horizontal stabilizers, but remained connected by the control cables. A compression wrinkle was noted on the left side of the bulkhead below the leading edge of the horizontal stabilizer. The vertical stabilizer, rudder, both horizontal stabilizers, both elevators, and the right