Accident Overview
During arrival, the aircraft was vectored for an NDB runway 06 approach. The weather at Raleigh-Durham was reported as 500 feet overcast, visibility 3 miles with fog, wind from 140° at 12 knots, and altimeter setting 30.01 inches of mercury. After being cleared for the approach, the aircraft crossed the final approach fix (FAF) at 2,100 feet MSL. Radar service was terminated, and frequency change was approved. When the aircraft did not arrive, a search was initiated.
Wreckage Examination
The wreckage was found approximately 2.5 miles southwest of runway 06, where the aircraft had struck trees and crashed. The elevation of the crash site was about 600 feet MSL. The minimum descent altitude (MDA) for the approach was 1,160 feet MSL with the local altimeter setting, or 1,260 feet with the Raleigh-Durham setting. Examination revealed that the aircraft hit trees while on runway heading in a wings-level attitude and was configured for landing. No preimpact part failure or malfunction was found.
Pilot Medical and Toxicology
Toxicological testing of the pilot-in-command's (PIC) blood showed 0.10 mg/l of diazepam and 0.09 mg/l of nordiazepam. Testing of his urine showed a metabolite of marijuana (11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid) at a level of 0.117 mg/l. The PIC had undergone surgery for malignant lymphoma in February 1989. He was restored to flight status on August 9, 1989, and cleared for PIC duty one week later. He continued flying while receiving maintenance chemotherapy, and associates noted that he tired easily. Both occupants were killed.
Probable Cause
The official probable cause was impairment of the PIC due to drugs/medication, chemotherapy, and fatigue; failure of the PIC to assure that the IFR (instrument) approach procedure was followed; and his failure to maintain the minimum descent altitude (MDA). Inadequate surveillance of the operation by company/operator/management personnel was a related factor.