What happened
During the descent phase of the flight, air traffic control issued several instructions to the pilot. At 14:07, the aircraft was cleared to descend from Flight Level 2D40 to Flight Level 190. Shortly after, at 14:09, the controller provided a clearance to descend to 15,000 feet, which the pilot acknowledged. However, when the controller later requested that the pilot expedite the descent through 16,000 feet to accommodate other traffic, the pilot failed to respond.
Between 14:10 and 14:17, the controller made ten separate attempts to establish contact with the crew, all of which went unanswered. While the aircraft eventually responded to an ident request at 14:17, subsequent instructions for a GPS approach were not acknowledged. Radar data showed that the aircraft remained at Flight Level 190 for over four minutes despite the clearance to descend. The aircraft then climbed to 20,300 feet before performing a series of descending turns. The final radar contact indicated the aircraft was descending at 15,900 feet. The aircraft eventually struck a rocky drainage trench at an elevation of 5,630 feet, 15 nautical miles east-southeast of the destination airport, in a wings-level, 40-degree nose-down attitude.
Findings
Post-impact inspections of the aircraft revealed that the flight control, electrical, and pressurization systems were all functioning normally and showed no anomalies. There was no evidence of an in-flight fire or catastrophic engine failure, as both engines were found to be operational at the time of impact. Weather conditions were not considered a factor, as only light rime icing was present in the area.
Investigation into the pilot's medical history revealed several significant factors, including medications for high blood pressure and cholesterol, as well as recent elevated blood sugar levels. Given the lack of mechanical or environmental failures, the circumstances suggest substantial pilot impairment or incapacitation. While it remains unconfirmed whether the event was caused by a medical emergency, such as a stroke or heart attack, or a physiological event like hypoxia, the evidence points toward the pilot being unable to maintain necessary communications and flight path control.