MOONEY M20R — Watertown, WI

What happened

The instrument-rated pilot was conducting a personal cross-country flight with a passenger. An airport surveillance camera captured the airplane climbing wings level into a 300-ft overcast ceiling shortly after takeoff. Based on a review of recorded flight track data, shortly after the airplane climbed into the clouds it entered a climbing left turn but did not establish a direct course to the intended destination or climb to 3,000 ft mean sea level (msl) as cleared by the air traffic controller before the takeoff. Rather, the airplane flew through the direct course while it climbed and descended before it ultimately entered a steep descending right turn. In the moments before the accident, the airplane exceeded the never exceed airspeed (VNE) as it descended more than 13,500 feet per minute (fpm) while in the steep right turn. A witness reported seeing the airplane descend “nose first” into a grass field and wooded area, which was followed by a large explosion.

The airplane fragmented upon impact with terrain and trees, but a wreckage layout confirmed that all major structural components and flight controls were accounted for at the accident site. Flight control continuity could not be confirmed due to extensive impact-related damage; however, the airplane’s recorded flight path established that the airplane turned left and right and both climbed and descended during the flight. Additionally, a sound spectrum analysis of recorded audio concluded that the engine was operating when the airplane impacted terrain. The recorded flight path was consistent with the pilot experiencing spatial disorientation while flying in instrument meteorological conditions (IMC). The pilot’s recent instrument flight experience could not be adequately assessed with the available logbook evidence.

FAA Forensic Sciences toxicological testing detected ethanol in both lung and muscle tissue of the pilot. The presence of ethanol in both specimens means that the possibility of alcohol consumption could not be excluded. The negative ethanol result from the autopsy toxicology report adds little information due to the relatively high reporting limit used. However, based on the condition of the pilot’s remains and the difference in ethanol levels between lung and muscle tissues, at least some of the detected ethanol likely was from postmortem production. If the pilot consumed ethanol, the ethanol level in lung tissue was not low enough to exclude some impairing effects, particularly in the presence of other potential central nervous system (CNS) depressant substances. Thus, whether ethanol effects contributed to the crash could not be determined.

The pilot’s toxicological results indicated the use of gabapentin. Based on the gabapentin levels measured in tissue, it is likely that the pilot was experiencing some effects from the gabapentin. Specific effects are uncertain; however, it is possible for gabapentin to affect the vestibular system and proprioception, which are important for spatial orientation. Toxicological results also indicated the pilot’s use of codeine. The use of codeine can cause CNS depression as well as increase the risk of gabapentin’s effects on the CNS. The toxicological results also indicated the pilot’s use of delta-8 THC. Delta-8 THC has the potential to alter perception and cause impairment. To what extent the combination of multiple CNS-active substances may have affected, the pilot’s cognitive processing and motor skills is unknown. Thus, based on the available information, it is possible that the pilot was impaired by the use of gabapentin, codeine, and delta-8 THC contributed to the accident. However, notably, the FAA prohibits an individual who uses gabapentin and/or delta-8 THC from acting as pilot-in-command of an aircraft.

The pilot reportedly had obstructive sleep apnea (OSA) treated with a continuous positive airway pressure (CPAP) device. Inadequately treated OSA can contribute to increased sleepiness, diminished attention, and cognition leading to an increased risk of performance errors. The pilot’s medical records regarding his use of a CPAP device were insufficient to determine whether he complied with OSA therapy; however, the pilot’s family reported that he was traveling with his CPAP device. Regardless, without additional information on the pilot’s compliance with OSA therapy, whether the effects of his OSA condition contributed to the accident could not be determined.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.