What happened
A pilot flying under visual flight rules (VFR) departed on a dark night for a cross-country flight. Weather forecasts prior to departure indicated clear skies and visibilities ranging from 4 to 10 miles along the route. Radar data analysis showed the airplane initially proceeded over land at 5,500 feet.
While crossing a 30-mile stretch of water approximately 34 miles west of Martha's Vineyard Airport, the airplane began a descent at a rate between 40 and 800 feet per minute. About 7 miles from the approaching coastline, the aircraft entered a right turn. The descent leveled off at 2,200 feet before the aircraft climbed back to 2,600 feet and initiated a left turn. During this left turn, a second descent began, reaching approximately 900 feet per minute. While still descending, the airplane entered a right turn, during which the airspeed and rate of descent increased significantly. The rate of descent eventually exceeded 4,700 feet per minute, and the aircraft struck the water in a nose-down attitude.
At the time of the accident, coastal airports reported visibilities between 5 and 8 miles. Other pilots operating on similar routes that night reported that haze had obscured the visual horizon while flying over the water.
The pilot had approximately 310 hours of total flight experience, including 55 hours at night. His experience in the accident aircraft totaled about 36 hours, with 9.4 hours flown at night. Of that time, only about 3 hours were completed without a certified flight instructor (CFI) on board, and only 0.8 hours of solo time included night operations and a night landing. In the 15 months preceding the accident, the pilot had flown to or from the destination area approximately 35 times, performing at least 17 of those legs without a CFI, five of which were at night. Within 100 days of the accident, the pilot had completed roughly 50 percent of an instrument training course.
The investigation
An examination of the airframe, engine, avionics, and systems revealed no evidence of a mechanical malfunction prior to the impact.