Accident Sequence
At 2144, the pilot contacted air traffic control and requested visual flight rules (VFR) flight following to the destination. This flight was the final leg of a four-leg trip that had begun approximately 1120 that morning. At 2220, the flight began a slow descent toward the destination airport. Radar data showed that the airplane executed a steady descent and flew a straight-line course toward Graham. The final radar return occurred 37 minutes later at an altitude of 3,000 feet, 8 miles southeast of Graham Municipal Airport. Radar coverage is not available below 3,000 feet. Two minutes after the final radar return, the pilot reported to air traffic control that the flight was two miles out and canceled VFR flight following. No further communications or distress calls were received from the airplane.
Witness Observations
Witnesses living near the accident site reported hearing an airplane flying low, observing dense fog, and hearing the sounds of an airplane crashing.
Weather Conditions
The nearest weather reporting station indicated that near the time of the accident, the temperature-dew point spread was within 2 degrees, visibilities were reduced to between 3 and 4 miles in fog, and the ceiling was decreasing from 600 feet broken to 400 feet overcast. The pilot did not request or receive updated weather from air traffic controllers during the flight.
Examination Findings
Examination of the airframe revealed no preimpact anomalies. The landing gear was extended and the flaps were retracted. Examination of both engines revealed evidence of power at the time of impact. At the time of the accident, the pilot's duty day exceeded 12 hours.
Probable Cause
According to the official findings, the probable cause of the accident was the pilot's failure to discontinue the approach after encountering instrument meteorological conditions, which resulted in controlled flight into terrain. Contributing factors were the dark night light condition, low ceiling, and reduced visibility due to fog.