What happened
During a flight conducted under instrument meteorological conditions, the pilot contacted air traffic control to request radar flight following, though the communication was made using an incorrect call sign. The flight path involved several altitude changes, with the aircraft climbing to 13,500 feet, descending to 11,500 feet, and returning to 13,500 feet before a final descent led to a terrain impact at 11,900 feet.
Approximately one minute before the collision, the pilot inquired with the air traffic controller regarding the minimum altitudes required for the intended route. The controller provided a minimum instrument altitude range of 15,000 to 15,300 feet. At the time of the incident, the moon had already set. While the pilot had previously communicated a planned altitude of 12,500 feet to a dispatcher, there was no evidence that a preflight weather briefing had been conducted.
Findings
Investigations into the flight operations revealed that the air traffic controller was aware of the aircraft's position, altitude, and proximity to terrain, yet no safety alert was issued to the pilot. Although the controller was monitoring the aircraft's general route, the descent into terrain occurred despite the controller's recent communication regarding higher minimum altitudes. A mechanical inspection of the engines and all related aircraft systems showed no signs of malfunction or anomalies prior to the impact.