Accident
At 0230 local time, a four-engine aircraft operated by an unspecified organization departed Apiay Air Force Base near Villavicencio, Colombia, on an anti-narcotic control flight over the southern part of the country and along the border with Ecuador. Approximately one hour into the flight, while cruising at an altitude of 7,000 feet in limited visibility, the aircraft struck the slope of Mount Patascoy de Santa Lucía, which has an elevation of 3,923 meters. The mountain is located about 35 kilometers southeast of San Juan de Pasto.
The wreckage was discovered five days later at an altitude of 2,100 meters. The aircraft was destroyed, and all seven occupants—five U.S. citizens and two Colombians—were killed.
Investigation
The official investigation determined the probable cause of the accident. Contributing factors were identified as the crew inputting wrong settings in the Flight Management System, causing a deviation from the prescribed route and leading the aircraft over mountainous terrain; the crew's relative inexperience; crew complacency; lack of visibility due to night conditions; lack of ground visual references; and crew fatigue due to insufficient rest time.
Probable Cause
The official probable cause is controlled flight into terrain due to navigational errors on the part of the flying crew.