What happened
While climbing to an assigned altitude of 14,000 feet, the aircraft's altitude readings began to deviate significantly from radar observations. Air traffic controllers noted that the pilot's reported altitude was consistently 10,000 feet lower than the altitude displayed on radar. After several inquiries, the controller instructed the pilot to cease altitude squawk transmissions. During the final radio contact, the pilot stated the aircraft had reached 14,000 feet.
For roughly 45 minutes, the flight continued toward its destination. However, the aircraft's trajectory then began to fluctuate, performing a 45-degree right turn to the northwest, followed by a 90-degree left turn, and finally a 180-degree right turn. Shortly after these maneuvers, the aircraft disappeared from radar tracking.
An investigation of the wreckage in the mountainous region showed that the aircraft had broken up in flight, with debris scattered across a 0.3 nautical mile area from east to west. Structural analysis revealed that the right wing had separated from the wing root in an upward direction, showing signs of structural overload. The right horizontal stabilizer also separated upward and aft, while the left stabilizer remained attached but was twisted. Additionally, both engines detached from the wings during the event.
Findings
Post-crash inspections of the engines and airframe showed no evidence of mechanical malfunction or failure. While the altimeters were too damaged for testing, medical examinations of the pilot revealed severe coronary artery disease, specifically a 95% narrowing of the left anterior descending coronary artery caused by plaque, along with a complete blockage by a thrombus. The pilot also had moderate diabetes. The investigation concluded that the pilot's behavior, including the altitude reporting errors, was consistent with hypoxia-induced incapacitation.