What happened
An instrument-rated private pilot was operating under IFR conditions on two separate flight plans throughout the day, traveling from Miami, Florida, to Groton, Connecticut. During the flight, the pilot updated the destination and alternate weather information while en route and was aware of the ongoing weather conditions.
After reporting the Babet intersection and receiving clearance for an approach to land for runway 23, the pilot descended the aircraft to approximately 680 feet MSL and engaged the autopilot. The aircraft subsequently underwent a slow descent below the minimum descent altitude of 660 feet. The aircraft impacted a wooded area located approximately 1.5 miles from the airport. At the time of the impact, the pilot was visually scanning out of the window and did not notice the loss of altitude.
The investigation
The pilot reported that there were no failures regarding any airplane systems or radios. An FAA coordinator inspected the aircraft and found nothing unusual with its mechanical condition. During the investigation, it was noted that the pilot reported fatigue at the time of the approach.