Flight History
According to air traffic control communication and radar data, the flight was operating under visual flight rules (VFR) over the top at approximately 7,900 feet when the pilot requested an instrument flight rules (IFR) clearance to the destination airport. The flight was issued an IFR clearance and subsequently cleared for the localizer runway 03 approach. Radar data indicated that the airplane intercepted the localizer and began tracking inbound. After reaching the final approach fix, the airplane entered a shallow descent but did not reach the minimum descent altitude (MDA) until after passing the missed approach point (MAP). The airplane flew past the MAP, continued to descend, and over flew the runway. The final radar return was captured at 1,200 feet and one mile northeast of the airport, where the airplane was later located.
Weather Information
The weather observation facility at the airport reported that, 11 minutes before the accident, the winds were from 140 degrees at 6 knots, ceiling 200 feet overcast, visibility 1/4 mile in fog, temperature 45°F, and dew point 45°F. A person who was at the airport at the time reported that the "clouds were low and visibility was poor."
Pilot Toxicology
Toxicological testing performed on the pilot by the FAA's Civil Aeromedical Institute revealed the following: 0.121 ug/ml/g amphetamine in blood, 0.419 ug/ml/g in liver, and detected in kidney; 4.595 ug/ml/g methamphetamine in blood, 5.34 ug/ml/g in liver, and 3.715 ug/ml/g in kidney; pseudoephedrine present in blood and liver.
Aircraft Examination
The airframe and engines were examined, and no anomalies were discovered that would have affected operation of the flight.
Probable Cause
The investigation determined the probable cause to be the pilot's failure to follow the instrument approach procedure and his continued descent below the prescribed minimum descent altitude. Contributory factors were the pilot's physical impairment from drugs, the low ceiling, fog, and dark night light conditions.