What happened
During a night flight under marginal VFR conditions, an aircraft struck mountainous terrain while in controlled flight. The flight was being conducted as part of a pilot's 14 CFR Part 135 instrument competency check. During the procedure, approach control provided the pilot with a specific heading and altitude to maintain. This instruction directed the aircraft into a different airspace sector where the altitude was lower than the required minimum vectoring altitude (MVA).
At the time of the incident, the air traffic controller was managing six different arrival sectors and was dealing with a high volume of incoming traffic. The controller failed to issue a safety alert despite the aircraft's descent into terrain-sensitive airspace. Additionally, the approach control facility supervisor, who was monitoring the controller's performance, did not identify or rectify the error regarding the altitude assignment.
Findings
Investigations revealed that the controller assigned a heading and altitude simultaneously that placed the aircraft below the MVA, violating FAA Order 7110.65, Section 5-6-1. This regulation mandates that if a VFR aircraft is given both a heading and altitude, the altitude must remain at or above the MVA. The controller indicated a lack of concern regarding the aircraft approaching higher MVA areas, citing the common practice of VFR flights operating below these altitudes. The primary contributing factor was the improper assignment of altitude and heading by the controller during a period of high workload.