Incident Overview
On the evening of the incident, an aircraft was dispatched to Philadelphia, Pennsylvania, on a passenger flight. After arriving, the pilot remained at the airport to pick up four additional passengers who were scheduled to arrive at approximately 2100 EST. At 2007, the pilot obtained a partial weather briefing and filed an instrument flight rules (IFR) flight plan to return to Pottstown.
The aircraft departed with an IFR clearance at 2145 EST and proceeded at 3,000 feet MSL, just above the cloud tops. During arrival, the pilot was cleared for a VOR-B approach to Pottstown Municipal Airport. He reported that he could see the airport beacon from over the VOR but observed patchy ground fog.
The approach was continued to the missed approach point, where the pilot lost sight of the beacon. He initiated a missed approach; however, when the throttle was advanced, no difference in engine sound was noted, except that the pilot recalled there may have been some "flutter in the engine." According to reports, the aircraft continued descending and slowing until it struck trees at 440 feet MSL, approximately 1 mile northwest of the airport. The airport elevation is 256 feet.
Investigation Findings
No preimpact mechanical failure was found in the aircraft. The temperature and dew point were both 48 degrees Fahrenheit. An icing probability chart indicated that serious carburetor icing conditions were present. However, the position of the carburetor heat control could not be verified.