Pearlington, MS, USA
N361DS
DIAMOND AIRCRAFT IND INC DA 40
Air traffic control radar data showed the airplane making multiple circles with altitude variations ranging from 8,400 feet mean sea level (msl) to 700 feet msl. A witness reported that he heard a single-engine airplane flying overhead and that he heard the engine changing pitch, which made him immediately look up. He saw what appeared to be a single-engine airplane doing “loops” near his house. He was able to see the silhouette of the airplane and the two white strobes under its wing tips. The engine pitch dropped as the airplane was climbing. About 3 seconds, later the witness could see the red and green lights on the airplane’s wing tips, as well as the strobes again as the engine pitch increased. He observed the airplane as it made “a couple more loops.” The airplane appeared to level out and continue flying west-northwest and, about 1 minute later, it made a turn toward the north. The airplane was located the following day in a wooded area about 5 miles from the witness’s home. Night visual meteorological conditions prevailed and the airplane was flying over sparsely lighted terrain at the time of the accident. The crash debris field indicated that the airplane was in a shallow, controlled descent at impact. Examination of the wreckage revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation. Based on the available information, it is likely that the pilot experienced spatial disorientation before impacting the ground. Although toxicological testing of the pilot’s blood specimens showed potentially lethal carbon monoxide levels, the testing also showed very low hemoglobin concentration, which suggests significant contamination (possibly during postaccident firefighting activities) that made the sample unsuitable for accurate testing. Examination of the airplane’s debris path found evidence to preclude any possibility that the pilot inhaled carbon monoxide during the postcrash fire, and examination of the airplane revealed no evidence of any precrash leaks in the exhaust system. Further, the pilot demonstrated the ability to talk coherently to air traffic controllers about 1 hour before the accident and to operate and maneuver the airplane during the flight. Given the absence of any detectable exhaust leak in the airplane, the uncertain quality of the specimen used for toxicological testing, the lack of confirmatory testing, and the pilot’s demonstrated abilities during the flight, it is unlikely that the pilot experienced any significant premortem exposure to carbon monoxide. Ethanol was detected in multiple tissues of the pilot, and the levels suggest that there was some degree of postmortem ethanol formation, although the levels also suggest that some of the alcohol present was from ingestion; however, the contamination of the pilot’s blood specimens raises the possibility that the detected ethanol levels are misleading as well. Thus, it is not possible to determine if the pilot was impaired at the time of the accident.
HISTORY OF FLIGHT On December 12, 2010, approximately 2200, central standard time, a Diamond DA-40, N361DS, was substantially damaged by impact and postcrash fire in a field near Pearlington, Mississippi. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91 with no flight plan filed. Night visual meteorological conditions prevailed. The private pilot was fatally injured. The flight departed Destin-Fort Walton Beach Airport (DTS), Destin, Florida, at 1924, en route to Stennis International Airport (HSA), Bay St. Louis, Mississippi. According to Gulfport approach control personnel, at 2021, the pilot was handed off from Mobile approach control to Gulfport approach when the flight was over the shoreline about 40 miles southeast of Gulfport-Biloxi International Airport (GPT). The airplane’s mode C transponder reported an altitude of 4,500 feet mean sea level (msl). At 2022, the pilot checked in with Gulfport approach and reported that the airplane was flying level at 4,500 feet. At 2052, the pilot reported he had HSA in sight, and he was 10 miles east of the airport. Radar service was then terminated. At 2053, the Automated Radar Terminal System (ARTS) tagged the airplane mode C at 5,000 msl, 7 miles east of HSA heading westbound. Between 2053 and 2200, ARTS showed the airplane flying around the Bay St. Louis area making multiple circles. There were altitude variations from a high of 8,400 feet msl at 2100 to 700 feet msl at 2138. About 2200, the last mode C target on the airplane was recorded at 2,000 feet msl. According to a witness located near the accident site, sometime between 2100 and 2200, he heard a single-engine airplane flying overhead. He said that he heard the engine changing pitch, which made him immediately look up. He saw what appeared to be a single-engine airplane doing loops near his house. He stated that he was able to see the silhouette of the airplane and the two white strobes under its wingtips. The engine pitch dropped as it was climbing. About 3 seconds later, he could see its red and green lights on the wing tips, as well as the strobes again as the engine pitch increased. He observed the airplane as it made “a couple more loops.” He was about to call 911 when the airplane appeared to level out and continue flying west-northwest. About 1 minute later, the airplane made a turn toward the north, and the pitch “normalized.” Local hunters found the downed airplane the next day in a wooded area about 5 miles from the witness’s home. PERSONNEL INFORMATION The pilot, age 44, held a private pilot certificate with ratings for airplane single-engine land, multi-engine land, and instrument airplane. The pilot was issued his pilots certificate on August 22, 2006.The pilot's most recent Federal Aviation Administration (FAA) medical examination was performed on February 16, 2009, and he was issued a second-class medical certificate with limitations for corrective lenses. The pilot reported 1,650 hours of flight time on his last medical application, and 30 flight hours within the last 6 months of his exam. The pilot’s logbook was located within the airplane and was destroyed by postimpact fire. AIRCRAFT INFORMATION The single-engine, four-seat, low-wing, fixed-gear airplane, serial number 40.261, was manufactured in 2003. The airplane was powered by a Lycoming IO-360-M1A, 180-horsepower engine. The airplane’s logbooks were destroyed by postimpact fire. Review of the last work invoice revealed that the last annual inspection was completed on August 20, 2010. At the time, the airframe and engine had 1,015 hours of operation. METEOROLOGICAL INFORMATION The 2055 recorded weather observation at HSA, located approximately 6 nautical miles northeast of the accident site, included winds from 270 degrees at 7 knots, clear skies, 10 miles visibility, temperature 33 degrees F, dew point 24 degrees F, and an altimeter setting of 30.12 inches of mercury. Civil twilight occurred at 1754. WRECKAGE AND IMPACT INFORMATION The wreckage was located in a wooded area 6 miles southwest from HSA. The wreckage debris path extended from a field at the beginning of a tree line. There was evidence of three landing gear strikes in the grass at the initial impact point. The airplane traveled approximately 75 feet before entering a tree line. The airplane collided with pine trees and traveled approximately 300 feet through the wooded area and came to rest on a heading of 300 degrees magnetic. The vegetation within the wooded area was very dry, and a postcrash fire was evident around the engine and other components of the airplane. The dry vegetation continued to smolder during examination of the wreckage. The wreckage was located at 30°19’ 20.5” north latitude, 089° 32’10.8” west longitude. The upper and lower engine fiberglass cowlings were fragmented throughout the debris field. The engine assembly was detached from the airframe and located along the debris path. The engine mounts remained attached to the engine. All accessories remained attached to the engine and were impact- and fire-damaged. The stainless steel and fiberglass firewall was buckled and fire-damaged. The nose landing gear was separated from the airframe. The propeller hub assembly remained attached to the crankshaft flange. The fiberglass spinner was fragmented throughout the debris path. The three-bladed wooden propeller was found splintered at the initial ground scar. Two blades were splintered at the propeller hub, and approximately 12 inches of the third blade remained attached to the hub. The forward cabin area windscreen was broken, and pieces were located throughout the debris field. The fiberglass forward cabin area was fragmented and fire-damaged. The lower forward spar was broken in half, and fragments were located throughout the debris path. The instrument panel was destroyed, and all switches and instruments were unreadable. Aileron, elevator, and rudder control continuity could not be confirmed, and all flight control push- and pull-tubes were broken and fragmented throughout the debris path. The flap actuator was found retracted, which is consistent with the flaps in the “up” position. The rear fiberglass cabin area was fragmented throughout the debris field. The rear passenger door was separated from the fuselage. The right wing was fragmented throughout the debris field. The right two aluminum fuel tanks were located along the debris path and contained residual amounts of fuel. Both fuel tanks were ruptured and buckled. The fuel cap was secure with a tight seal. The right flap was broken and located in the debris field. The right aileron was located along the debris path and was fragmented and broken. The right main landing gear strut was separated from the fuselage attachment point located along the debris field. The right main landing gear wheel and tire was separated from the strut and fire damaged. The aft fuselage and empennage was fragmented and located at the beginning of the tree line. The vertical stabilizer was fragmented. The rudder was separated from its attachment fittings and broken in half. The right and left horizontal stabilizers were separated from the empennage and were fragmented. The right and left elevators were fragmented and separated from their attachment fittings. The left wing was fragmented throughout the debris field. The left two aluminum fuel tanks were located along the debris path and contained residual amounts of fuel. Both fuel tanks were ruptured and buckled. The fuel cap was secure with a tight seal. The left flap was fragmented and located in the debris field. The left aileron was fragmented along the debris path. The left main landing gear strut was separated from the fuselage attachment point located along the debris field. The left main landing gear wheel and tire was separated from the strut. Examination of the engine revealed the engine exhaust tubes were connected to the engine and damaged. The engine muffler assembly was separated from the engine and damaged. The muffler assembly heat shroud was removed, and no carbon deposits were noted inside of the shroud. The muffler was recovered for further examination. Both magnetos were fire-damaged and could not produce spark. All ignition leads and the ignition harness were fire-damaged. The engine-driven fuel pump housing was fire-damaged, and only the pump arm remained attached to the engine. The fuel lines from the engine-driven fuel pump to the throttle body fuel control unit were fire-damaged and did not contain fuel. All oil supply lines were fire-damaged. All rocker covers were removed, and no damage was present on the valves or valve springs. The starter was separated from the engine and broken. The alternator was broken, and the armature was located along the debris path. The top sparkplugs were removed, and the electrodes exhibited light gray combustion deposits and were worn normally when compared to the Champion Check-A-Plug chart. A lighted borescope was used to examine the bottom plugs, and the electrodes exhibited light gray combustion deposits, and were worn normally when compared to the Check-A-Plug chart. The fuel flow divider was removed and disassembled, and the diaphragm was found intact. Fuel was not present in the fuel flow divider. The oil filter was destroyed and could not be examined. The accessory housing was removed, and the engine was rotated from the crankshaft flange. Compression and suction were obtained on all cylinders. The rocker arms and valves moved on all cylinders except No. 4 when the crankshaft was rotated. Push rods on the No. 4 cylinder were damaged. Continuity of the crankshaft was confirmed to the rear accessory gears. The interiors of all cylinders were examined using a lighted borescope, and no anomalies were noted. No preaccident mechanical malfunctions or failures were found that would have precluded normal operation of the airplane. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot on December 14, 2010, by the Coroner's Office, Hancock County, Mississippi, as authorized by the Hancock County Coroner. Three toxicological tests were performed on the pilot: one by the Garden Park Medical Center Laboratory, Gulfport, Mississippi; and two by the FAA Bioaeronautical Science Research Laboratory (CAMI), Oklahoma City, Oklahoma. The local toxicology report revealed 56.6 percent Carboxyhemoglobin (COHb) and stated that the specimen was taken from whole blood. A review of this toxicology report by the National Transportation Safety Board (NTSB) chief medical officer indicated that the testing was not confirmed by chromatography (which is considered more specific) and that the amount of available hemoglobin in the sample was not determined. The first CAMI toxicology was performed on March 17, 2011, and the report showed that 21% carbon monoxide was detected in cavity blood. The report also revealed positive ethanol values (as follows) and reported that there was putrefaction: 499 (mg/dL, mg/hg) ETHANOL detected in Blood (Cavity) 206 (mg/dL, mg/hg) ETHANOL detected in Heart 178 (mg/dL, mg/hg) ETHANOL detected in Muscle 150 (mg/dL, mg/hg) ETHANOL detected in Kidney 131 (mg/dL, mg/hg) ETHANOL detected in Lung 112 (mg/dL, mg/hg) ETHANOL detected in Liver 12 (mg/dL, mg/hg) N-BUTANOL detected in Blood (Cavity) 6 (mg/dL, mg/hg) N-PROPANOL detected in Blood (Cavity) The first CAMI toxicology report also revealed that 3.582 (ug/ml, ug/g) Acetaminophen detected in cavity blood. The second CAMI toxicology report was released on September 28, 2011, and the report revealed that the specimens that were used for carbon monoxide testing were unsuitable for analysis. The ethanol and drug values were the same as those reported in the first CAMI toxicology report. A review of the CAMI toxicology information by the NTSB chief medical officer found that the quality of the blood sample submitted to CAMI for testing contained so little hemoglobin that the sample was considered contaminated and COHb saturation could not be accurately determined. TEST AND RESEARCH The engine muffler was sent to the NTSB materials laboratory for examination. The engine muffler assembly had an overall oxidized appearance but no areas of pitting or excessive material thinning were identified. The muffler assembly had two areas where fractures had occurred. Examination of these fractures revealed that they had been caused by overstress due to impact forces. No evidence was identified that revealed the presence of any preexisting cracks. ADDITIONAL INFORMATION FAA Advisory Circular (AC) 60-4A, “Pilot’s Spatial Disorientation,” states, in part: “The attitude of an aircraft is generally determined by reference to the natural horizon or other visual references with the surface. If neither horizon nor surface references exist, the attitude of an aircraft must be determined by artificial means from the flight instruments. Sight, supported by other senses, allows the pilot to maintain orientation. However, during periods of low visibility, the supporting senses sometimes conflict with what is seen. When this happens, a pilot is particularly vulnerable to disorientation. The degree of disorientation may vary considerably with individual pilots. Spatial disorientation to a pilot means simply the inability to tell which way is ‘up.’” The AC notes that a disoriented pilot may place an aircraft in a dangerous attitude. The AC recommends that pilots obtain training and maintain proficiency in aircraft control by reference to instruments and to “not attempt visual flight rules flight when there is a possibility of getting trapped in deteriorating weather.” False visual reference illusions may cause you to orient your aircraft in relation to a false horizon. These illusions are caused by flying over a banked cloud, night flying over featureless terrain with ground lights that are indistinguishable from a dark sky with stars or night flying over a featureless terrain with a clearly defined pattern of ground lights and a dark starless sky.
The pilot’s controlled flight into terrain likely due to spatial disorientation, while flying over sparsely lighted terrain at night.
Source: NTSB Aviation Accident Database
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