Cessna 208 N40EA

The pilot was conducting a visual flight rules (VFR) cross-country repositioning flight at dusk in preparation for skydiving activities the following morning. Although he had accumulated more than 8,600 total flight hours, he did not hold an instrument rating. The ADS-B data for the flight showed that the pilot did not fly a direct route to the destination airport and that the airplane’s altitude varied throughout the flight. During the first half of the flight, the pilot flew the airplane northbound along a major interstate at an altitude of about 1,700 ft mean sea level (msl). He then turned left and flew the airplane west over a city and climbed to 3,100 ft msl before turning right to the north-northeast. Weather conditions along the latter portion of the route included areas of low ceilings and cloud cover. The airplane’s meandering flight path was consistent with a pilot attempting to avoid entering instrument meteorological conditions (IMC) and/or using ground lighting and roadways to navigate and maintain visual references. The ADS-B data showed that, in the final minute of the flight, the airplane entered a descending 180° turn to the right, and the descent rate increased steadily to greater than 12,000 ft per minute (fpm) until the data ended. Although the pilot’s initiation of the right turn may have been an attempt to avoid or exit IMC, a review of available weather information revealed that, about the time of the right turn, the airplane likely encountered and remained in IMC consisting of significantly reduced visibility and low ceilings while flying over a rural area with few ground lights or other visual references. Loss of external visual references during VFR flight presents a high risk of spatial disorientation and loss of control. Several risk factors for spatial disorientation were present in this accident: the pilot did not have an instrument rating and, thus, likely had limited experience flying in instrument meteorological conditions; the weather conditions included reduced visibility and low ceilings; and the flight occurred near dusk which would further limit the pilot’s ability to maintain outside visual reference when flying in areas of limited ground cultural lighting. Based on these factors, and the rapidly descending flight path and severely fragmented wreckage consistent with a high-energy impact, the pilot likely experienced spatial disorientation after entering IMC and subsequently lost control of the airplane. A postaccident examination of the wreckage revealed no evidence of any preimpact mechanical malfunction or failure that would have precluded normal operation. Although the pilot’s age, history of high blood pressure (which he reported at his most recent aviation medical examination), and possible diabetes or prediabetes (as suggested by the metformin detected by postmortem toxicological testing) were associated with some increased risk of having impairing cardiovascular disease, the pilot’s autopsy was too limited by injury to provide significant information about his cardiovascular health at the time of the accident. Although potentially impairing effects of diabetes, including fatigue and vision changes, could not be excluded based on the available medical evidence, the circumstances of the accident did not indicate that medical factors likely contributed to the accident.

Quoted verbatim from the NTSB record.