Flight History
The pilot, who was not instrument rated, obtained weather forecasts indicating visual flight rules (VFR) conditions with clear skies and visibilities varying between 4 to 10 miles along the intended route. The flight departed on a dark night. A performance study of radar data showed the airplane proceeded over land at an altitude of 5,500 feet. About 34 miles west of Martha's Vineyard Airport, while crossing a 30-mile stretch of water toward its destination, the airplane began a descent of 400 to 800 feet per minute (fpm). Approximately 7 miles from the approaching shore, the airplane initiated a right turn. The descent stopped at 2,200 feet, then climbed back to 2,600 feet and entered a left turn. During the left turn, the airplane began another descent that reached about 900 fpm. While still descending, it entered a right turn, during which the rate of descent and airspeed increased. The rate of descent eventually exceeded 4,700 fpm, and the airplane struck the water in a nose-down attitude.
Weather and Visibility
Airports along the coast reported visibilities between 5 and 8 miles. Other pilots flying similar routes on the night of the accident reported no visual horizon while flying over the water because of haze.
Pilot Information
The pilot's estimated total flight experience was about 310 hours, of which 55 hours were at night. In the accident airplane make and model, the pilot had about 36 hours total, including about 9.4 hours at night. Of those, about 3 hours were without a certified flight instructor (CFI) on board, and about 0.8 hour was flown at night and included a night landing. In the 15 months before the accident, the pilot had flown to or from the destination area about 35 times; at least 17 of those flight legs were without a CFI, of which 5 were at night. Within 100 days before the accident, the pilot had completed about 50 percent of a formal instrument training course.
Spatial Disorientation Information
A Federal Aviation Administration Advisory Circular (AC) 61-27C, "Instrument Flying: Coping with Illusions in Flight," states that illusions or false impressions occur when information provided by sensory organs is misinterpreted or inadequate, and that many illusions in flight could be caused by complex motions and certain visual scenes encountered under adverse weather conditions and at night. The AC also states that some illusions might lead to spatial disorientation or the inability to determine accurately the attitude or motion of the aircraft in relation to the earth's surface. According to AC 60-4A, "Pilot's Spatial Disorientation," tests with qualified instrument pilots indicated that it can take as long as 35 seconds to establish full control by instruments after a loss of visual reference of the earth's surface. AC 60-4A further states that surface references and the natural horizon may become obscured even though visibility may be above VFR minimums, and that an inability to perceive the natural horizon or surface references is common during flights over water, at night, in sparsely populated areas, and in low-visibility conditions.
Aircraft Examination
Examination of the airframe, systems, avionics, and engine did not reveal any evidence of a preimpact mechanical malfunction.