What happened
While performing an approach to the destination airport, the pilot requested vectors for a localizer approach to runway 19. Due to existing traffic, air traffic control provided a holding clearance. As the aircraft reached the holding fix at approximately 8,000 feet, the pilot notified controllers that the plane was encountering light icing conditions. Although air traffic control suggested increasing the altitude to 9,000 feet, the pilot initially declined the amended clearance before eventually accepting and climbing to the higher altitude.
Air traffic control informed the pilot that an approach clearance would be issued once a preceding aircraft had landed. At an altitude of roughly 9,200 feet, the pilot acknowledged the instruction. Radar surveillance indicated that the aircraft performed a 360-degree turn followed by a 270-degree turn on the non-holding side of the pattern. During these maneuvers, the aircraft's altitude fluctuated between 8,300 and 8,900 feet. These turns were significantly tighter than standard holding patterns, with radii measured between 0.1 and 0.4 nautical miles. Following these turns, the aircraft disappeared from radar and ceased all radio communication. The aircraft struck mountainous terrain during this phase of flight.
Findings
An inspection of the wreckage showed no evidence of mechanical failure prior to the impact. While another pilot in the vicinity reported moderate rime ice at 8,000 feet, they noted that they were clear of icing after climbing to between 9,000 and 10,000 feet. The tightness of the turns performed during the holding pattern was a notable deviation from standard procedures.