What happened
The aircraft was operating under visual flight rules but encountered deteriorating weather conditions during its arrival at Coatesville. There was no weather reporting station located at the airport, but forecasts from a station approximately 25 miles to the southeast in Philadelphia indicated occasional ceilings of 600 feet overcast and visibility of three miles with light rain showers and fog. Flight predictions also warned of turbulence below 5,000 feet due to wind shear, with frequent ceilings and visibility below 1,000 feet and three miles associated with stratus, light drizzle, and fog.
During the arrival phase, air traffic control vectored the aircraft for a VOR runway 29 approach, noting that the instrument landing system was out of service. On the first attempt, the pilot executed a missed approach. The pilot received new vectors to fly the approach again and stated he would proceed to Philadelphia if a landing could not be completed.
On the second approach, the aircraft descended below radar coverage at an altitude of 1,800 feet mean sea level, approximately three miles east-southeast of the airport. Subsequently, the aircraft crashed approximately one mile northeast of the runway threshold while in a steep nose-down attitude. The main wreckage came to rest 44 feet northeast of the principal impact point.
The investigation
Examination of the aircraft revealed no preimpact mechanical problems. However, investigators noted that the stabilator trim was in the full nose-down position at the time of the accident, although the system's integrity was not maintained during the crash sequence. A weather study indicated that cloud bases were at 900 feet mean sea level at the time of the incident.
Findings
The minimum descent altitude for the approach was 1,860 feet mean sea level, while the airport elevation was 662 feet. The pilot descended below the minimum descent altitude in low visibility conditions, likely due to a loss of visual reference in the reported fog and stratus.