ERA20FA096

The pilots’ loss of control in flight in freezing instrument meteorological conditions due to spatial disorientation and the cumulative effects of task saturation.

While on an instructional flight in icing and instrument meteorological conditions (IMC), the pilots indicated that they were having instrumentation difficulties to air traffic control. They initially reported a problem with the autopilot, then a navigational issue, which they later indicated were resolved, and finally they reported it was a problem with the left side attitude indicator. After air traffic control cleared them to their destination, the airplane entered a descending left turn, which continued into a 360° descending turn. An inflight breakup resulted, with the wreckage being scattered over 7,000 ft of wooded terrain. Examination of the engines revealed there were no anomalies that would have precluded normal operation prior to the accident. Control cable continuity was established from the flight controls in the cockpit to all flight control surfaces through multiple overload failures. The pitot-static system was examined, and no blockages were noted. Since there was rotational scoring noted on the vertical gyro and the directional gyro, it’s likely they were operating at the time of the accident. Furthermore, the left side attitude indicator examination revealed that there were no anomalies with the instrument. Examination of the deice valves for the deicing boots revealed that the left wing deice valve did not operate. Corrosion was visible in all three valves and it could not be determined if the corrosion was a result of postimpact environmental exposure. Furthermore, since the cockpit switch positions were compromised in the accident, it could not be determined if the pilots were operating the deicing system at the time of the accident. However, most of the pilot reports (PIREPs) in the area indicated light icing and the airplane performed a 6,000 ft per minute climb just before the loss of control. Given this information, it is unlikely the icing conditions made the airplane uncontrollable. A review of the pilots’ flight experience revealed that the pilot in the left seat did not hold a type rating for the accident airplane model but was scheduled to attend flight training to obtain such a type rating. The pilot in the right seat, who also held a flight instructor certificate, did hold a type rating for the airplane. Given that the remarks section of the filed flight plan described the flight as a “training flight” and the left-seat pilot’s plan to obtain a type rating for the accident airplane model, it is likely the pilot in the left seat was the flying pilot for the majority of the flight. Although the right-seat pilot's autopsy noted coronary artery disease, the condition was poorly described. The circumstances of the accident are not consistent with sudden physical impairment or incapacitation; therefore, it is unlikely it contributed to the event. Toxicology testing identified diphenhydramine, which can cause significant sedation, in the right-seat pilot’s blood. However, the level present at the time of the accident was too low to quantify. Therefore, it is unlikely effects from diphenhydramine contributed to the accident. Prior to entering the descending right turn, air traffic control noted that the airplane was not following assigned headings and altitudes and the pilots’ reported having autopilot problems. Subsequently, the pilots’ reported they were using the right attitude indicator as they had difficulties with the left-side indicator. Information was insufficient to evaluate whether the reported difficulties were the result of a malfunction of the autopilot or the pilots’ management of the autopilot system. However, the reported difficulties likely increased the pilots’ workload, may have diverted their attention while operating in IMC and icing conditions, resulting in task saturation, and may have increased their susceptibility to spatial disorientation. It is also possible that the onset of spatial disorientation was the beginning of the pilots’ difficulties maintaining the airplane’s flight track and what they perceived to be an instrumentation problem. Regardless, since the left seat pilot was not rated to fly the airplane, the right seat pilot’s workload would have increased by having to diagnose the issue, assess the situation, and maintain positive airplane control. The airplane’s track data are consistent with the known effects of spatial disorientation, leading to an inflight loss of control and subsequent inflight breakup.

Toxicology testing performed by the FAA’s Forensic Sciences Laboratory identified rosuvastatin in the left seat pilot’s blood and urine. This drug was not considered impairing. An autopsy was performed on the left seat pilot by the Division of Forensic Sciences, Georgia Bureau of Investigation. The cause of death was multiple blunt traumatic injuries, and the manner of death was accident. An autopsy was performed on the right seat pilot by the Division of Forensic Sciences, Georgia Bureau of Investigation. The cause of death was multiple blunt traumatic injuries, and the manner of death was accident. The examination was limited by the severity of injury. The autopsy noted “coronary artery disease” without any further description. Toxicology testing performed by the FAA’s Forensic Sciences Laboratory identified diphenhydramine (in an amount too low to quantify and lower than the lowest level believed to result in symptoms) and losartan in the right seat pilot’s blood and urine. While losartan is not considered impairing, diphenhydramine is sedating. Diphenhydramine is a sedating antihistamine used to treat allergy symptoms and as a sleep aid. It is available over the counter under the names Benadryl and Unisom. Diphenhydramine carries the following FDA warning: may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery). Compared to other antihistamines, diphenhydramine results in marked sedation; it is also classed as a CNS depressant and this is the rationale for its use as a sleep aid. Altered mood and impaired cognitive and psychomotor performance may also be observed. According to Federal Aviation Administration (FAA) airman records, the right seat pilot, the pilot-in-command, held a commercial pilot certificate with ratings for airplane multiengine land, airplane single-engine land, airplane single-engine sea, and instrument airplane. In addition, he held a flight instructor certificate with ratings for airplane single-engine, airplane multiengine, and instrument airplane. He was also type rated in the CE-500. His most recent second-class medical certificate was issued December 10, 2019. According to the pilot's logbook, he accumulated 5,924.4 total hours of flight time, of which, he accumulated 88.6 hours of flight time in the same make and model as the accident airplane in the year before the accident. The logbook also indicated that he accumulated 573.4 total hours of instrument flight time, of which, 40.7 hours were in the year prior to the accident. According to FAA airman records, the left seat pilot, held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. His most recent third-class medical certificate was issued January 10, 2019, at which time he reported 805 hours of total flight experience. According to an email and training materials located in the wreckage, the pilot was scheduled to attend flight training to obtain a CE-500 type rating. According to FAA records, the airplane was manufactured in 1981, and was most-recently registered to a corporation in January 2019. In addition, it was equipped with two Pratt & Whitney Canada, JT15D-1A series, engines, which could each produce 2,200 pounds of thrust. The most recent maintenance performed on the airplane was completed on February 5, 2020. At that time, a Phase B inspection was performed in accordance with the airframe manufacturer's maintenance manual, and at that time, the airplane had accumulated 8,078.7 hours of total time. In addition, the left engine had accumulated 8078.7 hours of total time since new and the right engine had accumulated 8034.7 hours of total time since new. According to the airplane flight manual, the airplane was equipped with anti-ice and deice systems. “The anti-ice system consists of bleed air heated engine inlets, bullet nose, stators, windshields (left and right), electrically heated pitot tubes, static ports, angle-of-attack probe (if installed) and wing leading edge segments ahead of each engine. The wing outboard of the electric elements, the horizontal stabilizer and vertical stabilizer are deiced by pneumatic boots. Windshield alcohol anti-ice is also provided as a backup system for the left windshield.” Furthermore, in the limitations section of the airplane flight manual it stated that the minimum flight crew for all operations was “1 pilot and 1 copilot or 1 pilot in the left-hand seat and the following equipment operative: 1 autopilot with approach coupling, 1 flight director, 1 boom microphone or headset mounted microphone, transponder ident switch on the pilot’s control wheel.” The main wreckage of the airplane was located in a wooded area, inverted, and partially submerged in a creek at an elevation of 703 ft msl. Several parts of the airplane were not located in the vicinity of the main wreckage but were in the wooded area surrounding the main wreckage, consistent with an inflight breakup. The debris path was about 7,000 ft long along a 005° magnetic heading. The wreckage was recovered to a salvage facility for further examination, which included the identification of parts that were separated in flight and were located along the debris path. The top of the fuselage was crushed downward, and the wings were wrinkled. Control cable continuity was established from the flight controls in the cockpit to all flight control surfaces through multiple overload failures. The pitot-static system was examined, and no blockages were noted. The wing deice inspection light, on the left side of the fuselage, was examined and the filament was not stretched. The left wing remained attached to the fuselage and exhibited crush damage. The left aileron remained attached to the left wing. The left flap remained attached to the wing and was in the retracted position. In addition, the left speed brake was in the stowed position. The outboard 8 ft section of the right wing was separated and located along the debris path. The aileron was separated from the outboard section of wing and the midsection was located along the debris path. The inboard section of the wing remained attached to the fuselage and was impact damaged. The fractured section of the spar caps of the right wing were examined and were bent in an upward direction. The fracture surfaces exhibited rough 45° angle surfaces, consistent with overload failures. Several sections of wing skin were located along the debris path. The horizontal stabilizers and elevators separated and were located along the debris path. The outboard 6 ft of the left horizontal stabilizer was separated from the inboard section and located along the debris path. The fractured section of the spar caps of the left horizontal stabilizer were bent in a downward direction. The inboard 2 ft of the left elevator was separated from the horizontal stabilizer and located along the debris path. The forward spar of the vertical stabilizer remained attached to the fuselage, was bent aft, and twisted to the right. The aft spar of the vertical stabilizer was located along the debris path. The rudder was separated from the fuselage and the 3 ft top section and 5 ft bottom section were recovered from the debris field. The engines remained attached to the fuselage and were submerged in creek water. They were removed from the fuselage to facilitate recovery and examination. The engine cowling was removed and both low-pressure compressors would not rotate. Both low-compressor turbine blades exhibited damaged and were bent the opposite direction of rotation. The inner stator vanes did not exhibit any damage. The fuel and oil filters were examined with no anomalies noted. There were no anomalies with the engines that would have precluded normal operation prior to the accident. Examination of the cockpit switches showed that they were compromised during impact which revealed unreliab