ERA24FA058

The pilot’s failure to maintain airplane control, which resulted in pilot-induced oscillations and a subsequent loss of control and impact with terrain.

After departure on a 430-nautical mile (nm) cross-country flight, initial controller-pilot communications and headings were unremarkable. However, as the airplane climbed through 6,500 ft mean sea level (msl) and became established enroute, a performance study of ADS-B data showed that the airplane’s altitude and airspeed began to vary as the airplane repeatedly descended and climbed with fluctuating airspeeds. These oscillations became increasingly more severe over about 25 minutes, with altitude deviations up to 1,500 ft and significant fluctuations in airspeed. An air traffic controller advised the pilot that the airplane was left of course; although the pilot acknowledged the controller, the deviations continued to worsen and the pilot stopped responding to radio calls. Faint emergency transmissions were later received from the pilot and passenger as the airplane continued to descend. During the final portion of the flight, the airplane exceeded a descent rate of 10,000 ft per minute with a groundspeed of about 228 knots before terrain impact. The increasing altitude and heading deviations, loss of communication, and rapid uncontrolled descent were consistent with a loss of airplane control. Flight instructors who had flown with the pilot before the accident indicated that she routinely demonstrated poor manual aircraft handling and struggled with cockpit automation, including autopilot and trim use. The pilot’s training history showed that she had demonstrated difficulty maintaining situational awareness, suggesting the high-performance airplane she had purchased about 1.5 years before the accident was beyond her level of pilot proficiency, something explicitly noted by one of the instructors who had flown with her. Postaccident examination of the airplane wreckage did not reveal evidence of any anomalies or mechanical irregularities that would have precluded normal operation, though the degree of fragmentation and fire damage precluded a complete evaluation of the airplane’s flight controls and autopilot system. Given the airplane’s heading was stable during the initial portion of the flight, it is likely that the pilot had been using the autopilot. Based on the pilot’s reported misunderstanding of that system, including, but not limited to the autopilot’s pitch inputs and the requirement for manual pitch trim application, it is possible that the pilot inadvertently mis-trimmed the airplane, which resulted in oscillations that were exacerbated by the pilot’s application of force on the control yoke. These kinds of pilot-induced oscillations can occur when manual yoke or pitch trim inputs are in conflict with the autopilot's pitch control inputs, leading to delayed, or out-of-sync, corrections, rather than a smooth, constant altitude hold. The airplane’s vertical profile as evidenced by the ADS-B data, was consistent with these kinds of pilot-induced oscillations. As the oscillations became stronger, the pilot may have ultimately been unable to control the airplane’s pitch, even with the autopilot disengaged, resulting in the loss of airplane control. Toxicology results indicated that the pilot had used a combination of medications that may be used to treat conditions such as anxiety and depression, which may have performance-impairing effects. However, no details about any associated underlying conditions were available from reviewed records. Additionally, the medications trazodone, alprazolam, and buspirone may cause psychomotor and cognitive impairment such as slowed reaction time, diminished situational awareness, and sedation. However, due to the extent of the pilot’s injuries, measurement of drug levels was limited to tissue specimens only, preventing reliable comparison to antemortem reference ranges in blood. Overall, the pilot may have been experiencing impairing effects of medication use or an associated underlying condition at the time of the accident, and such effects may have diminished her ability to render effective control inputs. However, available medical and circumstantial evidence was insufficient to establish whether such effects contributed to the accident, particularly given the pilot’s demonstrated baseline proficiency in the high-performance airplane.

On October 20, 2021, the pilot passed her Private Pilot Airplane Airmen Knowledge Test. On May 14, 2022, she passed her private pilot (single-engine land) practical test, at which time she had accumulated 193.2 hours total flight time. Of those hours, 182.6 were dual instruction received; nearly all of the hours were accomplished in a Piper PA-28-140 that she had purchased on June 15, 2021. The following year she sold PA-28-140 and subsequently bought the accident airplane on July 13, 2022. The pilot’s logbook was found at the accident site but was heavily damaged. The most recent logbook pages that were not damaged revealed the pilot had logged 390.3 hours total time as of August 14, 2023, about 3 months and 3 weeks before the accident flight. None of the pilot’s logbook endorsements were contained within the undamaged segment of logbook that was reviewed. An interview with one of the pilot’s former flight instructors was conducted. The instructor stated that she, “leaned on technology too much and did not have solid stick and rudder flying skills.” Regarding the systems on the airplane, specifically the trim and autopilot, he stated that she would often confuse the trim direction and would manually adjust the trim in the wrong direction. The instructor stated, “For instance, she could get flustered. If that trim was in the wrong position, if the autopilot was not happy, she would just disconnect it and fly manually.” On the autopilot, “She would press the Down or Up button repeatedly. I would just tell her to gently press and hold the button down,” she would “repeatedly” push it. A subsequent interview with the general manager of the pilot’s flight school indicated that her training progress was not meeting the necessary proficiency levels. He reported that several weeks before the accident she was given an instrument phase check and that it did not go well on almost all aspects of aircraft control, situational awareness, and risk management. He reported that he advised her that she was behind the Debonair and that he believed she had purchased more aircraft than she was ready for. “She and her father did not disagree when I repeated this assessment.” The airplane was equipped with a Continental IO-470-N six-cylinder, fuel-injected engine producing 260 horsepower. The airplane featured retractable landing gear and a constant-speed propeller, making it a complex and high-performance airplane. These systems require specific pilot management and add to the aircraft's complexity compared to fixed-landing gear, fixed-pitch propeller trainer airplanes. It was capable of a maximum structural cruising speed of 161 knots and had a never-exceed speed of 195 knots. The airplane was equipped with a Century 2000 autopilot. This model was a prompting autopilot, meaning automatic control of the elevator trim (auto trim) was not available on this system. When the autopilot displayed a flashing TRIM UP or TRIM DOWN on the annunciator, the pilot would need to manually move the trim control of the airplane in the direction indicated on the autopilot. When the autopilot determined that the trim condition was satisfied, the trim lamp on the annunciator would extinguish and the pilot could then stop trim action. There were 2 degrees of trim prompting: for a small trim error, the trim prompt will flash approximately once each second. A large trim error will cause the prompt to flash approximately 3 times per second. A large error not corrected for a period of approximately 2 minutes would sound an alert for 5 seconds. The alert would repeat every 2 minutes until the error was corrected. According to airworthiness records, the pilot’s previous airplane, the Piper PA-28-140, had fixed landing gear, a fixed-pitch propeller, and a 160-hp engine installed in accordance with a supplemental type certificate; it was not a high performance or complex airplane. FAA airworthiness records showed that the airplane had been equipped with a Bendix King/Tru Trac autopilot system. Its cruise speed was about 110 kts with a maximum speed of 125 kts. According FAA medical records, the 44-year-old pilot’s last aviation medical examination was January 20, 2023. At that time, she reported using the medication fexofenadine (an over-the-counter, non-sedating antihistamine commonly used to treat symptoms of seasonal allergies). She otherwise reported no active medical conditions. The pilot was issued a third-class medical certificate with the limitation that she must wear corrective lenses to meet vision standards at all distances. The Middle Tennessee Regional Forensic Center performed the pilot’s autopsy for the Giles County Medical Examiner. According to the pilot’s autopsy report, her cause of death was multiple injuries, and her manner of death was accident. Due to the extent of her injuries, the autopsy was limited for evaluation of natural disease. At the request of the Middle Tennessee Regional Forensic Center, NMS Labs performed toxicological testing of postmortem liver tissue from the pilot. Alprazolam was detected at 530 ng/g. Alpha-hydroxyalprazolam was detected at 56 ng/g. The FAA Forensic Sciences Laboratory also performed toxicological testing of postmortem specimens from the pilot. Alprazolam was detected in liver tissue at 222 ng/g and was detected in muscle tissue at 81 ng/g. Alpha-hydroxyalprazolam was detected in liver tissue at 57 ng/g and was detected in muscle tissue at 4 ng/g. Trazodone was detected in liver tissue at 286 ng/g and was detected in muscle tissue at 56 ng/g. Buspirone was detected in liver tissue at 55.5 ng/g and was detected in muscle tissue at 3.8 ng/g. Ondansetron, propranolol, fexofenadine, and azacyclonol were detected in both liver and muscle tissue. Oxymetazoline was detected in liver tissue and was not detected in muscle tissue. Alprazolam (sometimes marketed as Xanax) is a potent prescription benzodiazepine medication used to treat generalized anxiety disorders and panic disorders. It typically carries a warning that use may cause central nervous system depression including increased sedation, reduced concentration, and reduced inhibitions. Alprazolam generally carries a warning that users should avoid engaging in hazardous occupations or activities requiring complete mental alertness such as operating machinery or driving a motor vehicle. Alpha-hydroxyalprazolam is an active metabolite of alprazolam. According to the FAA, alprazolam is a Do Not Issue/Do Not Fly medication. Trazodone is a prescription antidepressant medication that may be used to treat major depression, insomnia, generalized anxiety disorders, panic disorders and post-traumatic stress disorders. It typically carries a warning that use may slow thinking and impair motor skills, and that users should not drive, operate heavy machinery, or do other dangerous activities until they know how the drug affects them. The FAA considers trazodone a Do Not Issue/Do Not Fly medication. Buspirone is a prescription medication commonly used to treat anxiety. Use of buspirone may cause dizziness. Buspirone generally carries a warning that users should be cautious operating a motor vehicle or heavy machinery until they know how the drug will affect them. According to the FAA, buspirone is a Do Not Fly medication. Ondansetron is a prescription medication commonly used to treat and prevent nausea and vomiting. Multiple studies have found no significant effect of ondansetron on cognitive and psychomotor performance. According to the FAA medical case review for this investigation, ondansetron is disqualifying for FAA medical certification due to side effects including serious heart rhythm irregularities, drowsiness, and dizziness. Propranolol is a prescription medication commonly used to treat high blood pressure, migraine headaches, and chest pain caused by reduced blood flow to the heart (angina). Propranolol also may be used to treat various fo