HISTORY OF FLIGHT On September 23, 2011, about 0853 eastern daylight time, N54WB, an experimental amateur-built Thorp T-18, owned and operated by the private pilot, sustained substantial damage when it impacted a semi-trailer and terrain while on approach to runway 9 at the Plainwell Municipal Airport (61D), near Plainwell, Michigan. A ground fire occurred. The pilot was fatally injured. Visual meteorological conditions prevailed at the time of the personal flight. The flight originated from the Tulip City Airport, near Holland, Michigan, about 0830. The accident airplane was the second airplane in a flight of two airplanes destined for 61D. The pilot in the first airplane stated that there were no radio transmissions by the accident pilot of any mechanical malfunctions and that the accident pilot asked him to keep up his speed on final. He stated that there was a haze layer that he had to fly through which was located about 400 feet above ground level. The haze layer was localized around the river and airport. He stated that the visibility under the haze layer was about three miles. A witness, working on a bridge near the accident site, reported to the Michigan Highway Police that he observed that the second plane was close to the first airplane. He stated that both airplanes were “quite” low on approach. He indicated that the accident airplane impacted the semitrailer and “flipped” into the ditch embankment west of runway 9. Another witness who was in a southbound vehicle saw the airplane impact the semitrailer. This witness indicated the visibility was “good” and that he did not see any fog. A ground fire ensued when the airplane impacted terrain. PERSONNEL INFORMATION The pilot, age 73, held a private pilot certificate with single-engine land and instrument airplane ratings. His most recent medical certificate was a third class issued on July 20, 2011, without any limitations. A family member estimated that the pilot had accumulated approximately 1,921 hours of total flight time and 1,311 hours of total flight time in the accident airplane. AIRCRAFT INFORMATION The plans to build the accident airplane were sold to the pilot on September 27, 1974. A logbook endorsement showed that the last condition inspection was completed on March 2, 2011. There were no airframe hours listed in that endorsement entry. However, a family member indicated that the airplane accumulated about 1,311 hours of total flight time. METEOROLOGICAL INFORMATION At 0853, the recorded weather at the Kalamazoo/Battle Creek International Airport, located about 15 nautical miles and 165 degrees from the accident site, was: wind calm; visibility 6 statute miles; present weather mist; sky condition clear; temperature 11 degrees C; dew point 9 degrees C; altimeter 30.09 inches of mercury. AIRPORT INFORMATION 61D is a public, non-towered, airport located about 2 miles north of Plainwell, Michigan, at a surveyed elevation of 722 feet above mean sea level. The airport featured two runways: 9/27 and 1/19. Runway 9, which was 2,650 feet by 50 feet dry asphalt, had a 17-foot road, 201 feet from the runway end, a 4-foot fence, 50 feet from the runway end; and a 17-foot road, 140 feet from the runway end entries listed as obstructions. The runway had 191 foot displaced threshold. WRECKAGE AND IMPACT INFORMATION An on-scene examination of the wreckage was conducted. All of the flight control surfaces were found with the wreckage. The cabin area was melted, charred, and deformed consistent with involvement with a ground fire. The outer portions of the flight controls’ push-pull tubes were intact and their respective control surface moved when the tubes were moved by hand. The rudder control cables were intact and the rudder moved when the cables were moved by hand. No flight control preimpact anomalies were detected. The engine produced a thumb compression at all cylinders when the propeller was rotated by hand. The magneto sustained fire damage and its internal distributor gear was melted. The magneto produced spark at its center electrode when it was rotated by hand. The mechanical fuel pump ejected a liquid when its pump lever was manipulated by hand. No engine preimpact anomalies were detected. MEDICAL AND PATHOLOGICAL INFORMATION The Allegan County Medical Examiner arranged for an autopsy to be performed on the pilot. The autopsy listed the cause of death as smoke and soot inhalation and thermal burns. The FAA Civil Aerospace Medical Institute prepared a Final Forensic Toxicology Accident Report. The report was negative for the tests performed.