Primary finding
Probable cause
The student pilot's decision to take off from a partially-lit grass runway in dark night, marginal visual flight rules conditions, which resulted in spatial disorientation, an exceedance of the airplane's critical angle of attack, and an aerodynamic stall.
Investigator assessment
Analysis narrative
The student pilot departed in dark night, marginal visual flight rules (MVFR) conditions from his private grass runway that was partially lit with solar lights. A witness heard the airplane depart followed by the sound of a crash, and when he arrived at the airstrip, he observed a light layer of fog over the runway. The airplane came to rest in heavily-wooded terrain adjacent to the runway. Examination of the airplane and engine revealed no anomalies that would have precluded normal operation before impact. Data downloaded from an onboard GPS unit revealed that, after departure, the airplane made a climbing right turn to an altitude of 407 ft. It then descended to 256 ft and reached a maximum airspeed of 95 knots (kts) while continuing the right turn. The airplane then climbed in a right, 30° bank to a maximum altitude of 666 ft while slowing to an airspeed of 32 kts, which was well below the minimum stall speed. The airplane then rolled to the right and entered a rapid descent before the data ended. Conditions conducive to the development of spatial disorientation were present, including the dark night, MVFR conditions and a noninstrument-rated student pilot. Additionally, the airplane's track data, which reflects spiral-like maneuvering, and a wreckage distribution consistent with a loss-of-control, stall-type vertical descent, are consistent with the known effects of spatial disorientation. Based on this evidence, the student pilot most likely experienced spatial disorientation after takeoff, which led to the airplane exceeding its critical angle of attack and an aerodynamic stall.
Source record
Factual narrative
HISTORY OF FLIGHT On September 20, 2017, at 0601 eastern daylight time, a Cessna 150G, N3875J, was substantially damaged when it collided with terrain shortly after takeoff from a private airstrip near Rhine, Georgia. The student pilot was fatally injured. The airplane was owned by the pilot who was operating it as a Title 14 Code of Federal Regulations Part 91 personal flight. Dark night marginal visual flight rules (MVFR) conditions prevailed in the area and no flight plan was filed for the flight, which was destined for Turner County Airport (75J), Ashburn, Georgia. On the morning of the accident, the student pilot, who was the owner of the airplane, planned to pick up his flight instructor in Ashburn before flying to St. Simon's, Georgia, where he was scheduled to take his private pilot practical test the following day. The instructor had checked the weather that morning and saw that that there was fog reported in some areas, so he called the student, who did not answer his phone. The instructor then received a text from the student that stated, "I'll see you in a few." The instructor responded, "ok;" this was his last communication he had with the student pilot. A witness stated that he had just stepped out of his home when he heard an airplane with the engine "full throttle." It was dark outside and the sun was not up. He said that he never saw the airplane, but it sounded like the airplane took off, made a turn, then crashed. The witness then drove 3/4 mile to the airstrip, where the student pilot also had a business. When he arrived, he observed "light" fog over the airstrip. The witness then spoke with the student pilot's employees and told them that he thought the airplane had crashed. The student pilot's cousin and uncle, who were also both pilots, initiated an air search and located the airplane via the airplane's ELT about 0710. The airplane was equipped with a hand-held Garmin GPSMAP 396. The device recorded the date, time, latitude, longitude, GPS altitude, and an averaged groundspeed and track. An NTSB airplane performance specialist conducted an airplane performance study based on the data retrieved from the device. According to the study, the airplane departed about 05:59:47 and entered a climbing right turn, reaching an altitude of 407 ft at 06:00:40. The airplane then descended to 256 ft while continuing the right turn, reaching its maximum airspeed of 95 knots (kts). The airplane then climbed in a tightening right turn to a maximum altitude of 666 ft at which point the lowest airspeed, 32 kts, was recorded at 06:01:11; the bank angle at that time was 30° right wing down. The airplane then quickly lost altitude and rolled right, losing about 440 ft in 13 seconds. By 06:01:24, the airplane had descended to 226 ft before the last data point was recorded at 06:01:33 at an altitude of 279 ft. An airspeed of 32 kts at a calculated bank angle of 30° right wing down is below the manufacturer's minimum stall speed for all configurations and bank angles. PERSONNEL INFORMATION The student pilot's most recent Federal Aviation Administration (FAA) third-class medical certificate was issued on April 13, 2017. A review of his logbook revealed that he had accrued a total of 236 flight hours, all of which were in the accident airplane. The student pilot had logged 8.3 hours of night time experience; however, none of those flights included taking off or landing at his private airstrip at night. The student pilot's instructor stated that he knew "for a fact" that the student pilot had departed at least "30-40" times from his private airstrip at night. He had advised the pilot not to do so on several occasions because it was not safe. The strip was in poor condition and not properly lighted. The instructor also learned after the accident that the student pilot had given airplane rides to several family members and friends. He described the student pilot as a "good pilot" but "very head strong." He had "no fear – saw no danger." The instructor said that the student pilot always checked the weather before a flight but that he "didn't know weather" like a more experienced pilot would. AIRCRAFT INFORMATION The Cessna 150G is a two-seat, high-wing airplane equipped with a Continental O-200A engine. A review of the airframe maintenance logbook revealed that the most recent annual inspection was performed on March 2, 2017, at a total tachometer time of 5,534.8 hours. The most recent 100-hour inspection was performed on July 11, 2017, at a total tachometer time of 5,588.83 hours. METEOROLOGICAL INFORMATION A review of weather observations from Fitzgerald Airport, (FZG), Fitzgerald, Georgia, about 13 miles southwest of the accident site, revealed that MVFR conditions prevailed at the time of the accident with visibility restricted by mist. At 0555, the weather at FZG included calm wind, 4 miles visibility, mist, clear skies below 12,000 ft, temperature 22°C, dew point 22°C, and an altimeter setting of 30.01 inches of mercury. At 0615, FZG reported calm wind, 3 miles visibility, mist, clear skies, temperature 22°C, dew point 22°C, and an altimeter setting of 30.01 inches of mercury. GOES-13 infrared images taken at 0615 depicted clear skies over the accident site with a mid-level band of clouds near 14,000 ft to the northeast and east. The image could not discriminate between any low mist or fog and the surface temperatures at the time of the image. According to the U.S. Naval Observatory, civil twilight in Rhine, Georgia, began at 0656 and sunrise was at 0720. The moon phase was "new" at 0130. AIRPORT INFORMATION The student pilot co-owned the private airstrip from which he departed. According to family, the grass runway was about 4,200 ft long, oriented southwest/northeast, and partially lighted with solar lights placed every 200 ft. The pilot was known to taxi to the end of the runway and depart to the south. After departure, he always made a 360° turn over the airport and confirmed that the airplane was performing normally before departing for his destination. WRECKAGE EXAMINATION The airplane came to rest in wooded terrain adjacent to the private airstrip. The initial impact point was an approximate 80-ft-tall pine tree. The airplane came to rest about 70 ft from the initial impact point. Several tree branches were strewn along the wreckage path. Several of these tree limbs were fractured and exhibited 45° angular cuts. These cuts were flat and exhibited black paint transfer marks consistent with propeller contact. There was no postimpact fire. The main wreckage came to rest upright with the tail section bent over the top of the airplane. Both wings sustained extensive leading edge impact damage. The center section of wing was partially separated from the airframe. The engine and propeller remained attached to the airplane. A small section of the outboard wing, along with the tip, separated and was found adjacent to the right wing. The left wing tip separated and was found several feet away from the main wreckage. The tip portion of the vertical stabilizer was also damaged. Flight control cable continuity was established for all flight controls to the cockpit, and the wing flaps were fully retracted. The main right wing aileron cable was found separated. The fractured ends were frayed consistent with overload stress. The elevator trim tab was found 5° tab down (nose up). The right and left wing fuel caps were secure, but the right wing fuel tank was breached. Fuel was noted draining from both wings during recovery of the airplane. A fuel receipt found in the airplane revealed that the pilot had purchased 20 gallons of 100LL aviation fuel the day before the accident. The fuel selector was in the "on" position. The gascolator remained attached to the firewall. The bowl contained some fuel and the screen was absent of debris. The carburetor was removed from the eng