HISTORY OF FLIGHTOn February 1, 2019, about 1315 eastern standard time, a Piper PA-32RT-300, N3016L, was presumed destroyed after radar contact was lost over the Atlantic Ocean. The private pilot and passenger were presumed fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. A review of voice, radar, and weather data revealed that the airplane departed Palm Beach County Park Airport (LNA), West Palm Beach, Florida, under visual flight rules about 1300. The pilot subsequently obtained an instrument flight rules (IFR) clearance to Leonard M. Thompson International Airport (MYAM), Marsh Harbour, The Bahamas. The controller cleared the airplane to progressively higher altitudes and provided vectors to avoid areas of precipitation in its flight path. About 1305, the controller instructed the pilot to fly heading 080° to avoid weather and described an area of light and moderate precipitation at the pilot's eleven o'clock position and 10 miles ahead. The pilot acknowledged. About 2 minutes later, the controller instructed the pilot to turn 10° to the right in order to stay away from the precipitation. About 1309, the controller instructed the pilot to turn another 10° right to remain clear of precipitation. The pilot read back the instructions and said, "I don't know what happened my autopilot it just kicked off." The controller acknowledged the pilot and instructed him to climb and maintain 6,000 ft; the pilot repeated the altitude assignment. About 1310, the controller again instructed the pilot to turn 10° right for weather and stated that the airplane did not appear to be on the correct heading. The pilot stated that he was "really fighting" to maintain heading. One minute later, the controller informed the pilot that the airplane had turned south and asked if he required assistance. The pilot replied, "it's just really squirrelly up here it's weird." About 1312, the pilot contacted the controller and stated that there were some "really weird winds up here." The controller advised that the airplane was turning north toward an area of heavier precipitation and instructed the pilot to turn south toward "any heading." The pilot stated that the airplane was having autopilot issues and that he was going to turn off the autopilot and fly manually. About 1313, the controller advised the pilot that it appeared the airplane was heading eastbound and instructed him to maintain 6,000 ft. The controller also stated that he would advise the center controller that the airplane was having "some sort of an autopilot issue." About 1314, the controller advised the pilot that the airplane had turned back to the northwest and asked the pilot if he was going to return to an eastbound heading. The pilot responded that he was "fine," that his instruments were "acting really goofy" and that he would turn the airplane to a 090° heading. The controller instructed the pilot to maintain 6,000 ft and no higher than 7,000 ft. The pilot did not respond. Shortly thereafter, the airplane entered a sharp right turn from a northerly heading and began to descend. The radar track showed the airplane in an increasingly steep right turn as it rapidly descended and was lost from radar about 1315 in an area that depicted heavy precipitation. The United States Coast Guard conducted a search for the airplane by air and sea over an area of 1,115 square miles without success. After 36 hours, the search was suspended on February 3, 2019. PERSONNEL INFORMATIONThe pilot's personal logbook was not recovered, and neither his total instrument flight experience nor the recency of that experience could be determined. METEOROLOGICAL INFORMATIONThe accident pilot received a weather briefing through Leidos Flight Service at 1200. The briefer provided the convective outlook, Center Weather Advisory, METARs, and winds aloft. The accident pilot asked about the line of weather off the coast and stated that if it was moving north, he would fly south of it. The briefer responded that the line of weather was "just sitting there." The accident pilot told the briefer he "saw that one little red blob out there." The approximate cloud-top heights over the accident site were 16,000 ft mean sea level (msl), and a National Weather Service National Composite Radar Mosaic for 1315 at the approximate location of the accident site depicted 35- to 55-decibel (dBZ) echoes above the accident site. Radar data indicated that the airplane first entered precipitation between 1303 and 1309; reflectivity values between 30 and 50 dBZ, or moderate to heavy rain intensity echoes, were located above the accident site at the accident time (See figure 1). The reflectivity bands were moving from south to north. Figure 1. KAMX WSR-88D 0.5° elevation scan initiated at 1309:27 with the accident site marked with a black circle, the accident flight track in pink The Center Weather Advisory valid for the accident site at the accident time warned of areas of moderate rain showers and isolated thunderstorms with heavy precipitation with tops to 28,000 ft. ADDITIONAL INFORMATIONThe FAA Civil Aeromedical Institute's publication, "Introduction to Aviation Physiology," defines spatial disorientation as a loss of proper bearings or a state of mental confusion as to position, location, or movement relative to the position of the earth. Factors contributing to spatial disorientation include changes in acceleration, flight in instrument meteorological conditions (IMC), frequent transfer between visual meteorological conditions (VMC) and IMC, and unperceived changes in aircraft attitude. The FAA's Airplane Flying Handbook (FAA-H-8083-3B) describes some hazards associated with flying when the ground or horizon are obscured. The handbook states, in part: The vestibular sense (motion sensing by the inner ear) can and will confuse the pilot. Because of inertia, the sensory areas of the inner ear cannot detect slight changes in airplane attitude, nor can they accurately sense attitude changes that occur at a uniform rate over a period of time. On the other hand, false sensations are often generated, leading the pilot to believe the attitude of the airplane has changed when, in fact, it has not. These false sensations result in the pilot experiencing spatial disorientation.