What happened
The pilot was cleared for a Non-Directional Beacon (NDB) approach to Fitchburg Municipal Airport, which has an elevation of 350 feet. The airport's NDB was located on the field itself. The published Minimum Descent Altitude (MDA) for this procedure was 1,140 feet Mean Sea Level (MSL).
The approach procedure required the aircraft to fly outbound from the NDB on a 137-degree bearing, execute a procedure turn, and then track inbound on a final approach course of 317 degrees. The missed approach instructions directed the pilot to make a climbing right turn to 2,500 feet, proceed direct to the NDB, and hold.
The pilot initiated the approach sequence. At the time of the accident, the pilot believed he had reached the missed approach point located over the airport. However, the aircraft impacted the side of a tree-covered hill approximately 2.5 miles southwest of the airport. The collision occurred while the aircraft was in level flight at an altitude of approximately 1,150 feet MSL.