What happened
While operating an approach to runway 08 via the Asort transition for a scheduled medevac mission, the crew was navigating toward the localizer at Asort. The flight was descending through 9,500 feet when they reported being inbound. Shortly after, while passing through 8,200 feet and approximately 14 miles west of the Dibol intersection, the crew made their final radio transmission. The Learjet subsequently struck a mountainside at an elevation of 3,500 feet MSL. There were four fatalities, involving both pilots and two medical doctors.
Findings
Investigation into the crash revealed that no mechanical failures occurred prior to the impact. Instead, the accident was driven by improper use of navigation equipment and a premature descent. Although both navigation systems were tuned to the correct frequency (10D9.9 MHz), the DME control head had been left in the 'hold' position. This error caused the distance measurements to remain locked to the SSR vortac rather than switching to the I-JDL source. Consequently, the crew became disoriented regarding their exact position and began descending below safe altitudes. Contributing environmental factors included low visibility, cloud cover, and the presence of rising mountainous terrain during night operations.