Background
On June 7, 2009, about 1745 central daylight time, a Gulfstream American Corporation model AA-5B (Tiger), registration N448DM, was destroyed in an impact with terrain near Humbird, Wisconsin. The airplane was owned and operated by a non-instrument rated private pilot. The personal flight was conducted under 14 CFR Part 91 without a flight plan. Instrument meteorological conditions prevailed at the time of the accident. The pilot and his passenger were fatally injured.
Flight History
The flight departed at 1643 from Lake Elmo Airport (21D) in St. Paul, Minnesota, destined for Sheboygan County Memorial Airport (KSBM) in Sheboygan, Wisconsin. The pilot had contacted the Lansing Automated Flight Service Station (AFSS) at 1043 for a weather briefing, during which the briefer noted that VFR flight was not recommended due to an active advisory for widespread IMC along the planned route. Low overcast ceilings of 400-1,200 feet AGL, rain showers, and isolated thunderstorms with cloud tops reaching 34,000 feet were reported. The pilot stated he would call back later. At 1558, the pilot contacted the Washington AFSS for an updated briefing, again advised four times that VFR flight was not recommended due to widespread IMC, with ceilings of 900-1,500 feet AGL and forecasts of layered clouds up to 20,000 feet, scattered light rain showers, and isolated thunderstorms. The pilot did not file a flight plan.
Radar data showed a single VFR beacon track originating from 21D at 1643:31, proceeding south-southeast at 1,900-2,000 feet MSL. The last radar return was at 1708:18 over Durand, Wisconsin, at 1,900 feet MSL, approximately 42.6 nautical miles west of the accident site, at the lower altitude limit of radar coverage.
Several witnesses near the accident site reported hearing an airplane but could not see it due to low cloud ceiling, fog, and light precipitation. They noted the engine sound operating at high speed and fluctuating in loudness several times before hearing a ground impact. The accident site was located about 2045 by local law enforcement and property owners.
Aircraft Information
The accident airplane was a 1978 Gulfstream American Corporation model AA-5B (Tiger), serial number AA5B0976, a low-wing, all-metal, four-place monoplane with a certified maximum takeoff weight of 2,400 lbs. It was equipped with a Lycoming O-360-A4K reciprocating engine (180 horsepower) driving a Sensenich fixed-pitch, two-blade metal propeller. The airplane had a standard airworthiness certificate issued October 26, 1978. The pilot purchased the airplane on April 30, 2005. Total service time was 1,110 hours; the last annual inspection was completed July 3, 2008, at 1,057 hours. Static system, altimeter, and transponder tests were performed September 25, 2007. No unresolved airworthiness issues were noted.
Personnel Information
The pilot, age 45, held a private pilot certificate with an airplane single-engine land rating issued February 17, 2005. He was not instrument rated. His last aviation medical examination was February 5, 2009, resulting in a third-class medical certificate with no limitations. No accident, incident, or enforcement actions were on record. His logbook showed 271.6 total flight hours, including 189.6 as pilot-in-command, 271.6 hours in single-engine airplanes, 36.6 hours at night, and 4.2 hours in simulated instrument conditions. No time was logged in actual instrument conditions. He had 171.5 hours in the AA-5B. In the preceding 90 days, he flew 18.6 hours; in the preceding 30 days, 8.4 hours, all in the accident airplane. He had not flown in the 24 hours before the accident.
Weather Information
The nearest reporting station was Chippewa Valley Regional Airport (KEAU) in Eau Claire, Wisconsin, about 30 nautical miles northwest of the accident site. At 1756, the automated surface observing system reported wind 090 degrees true at 9 knots, visibility 10 miles, overcast ceiling at 1,700 feet AGL, temperature 12°C, dew point 8°C, and altimeter 29.96 inches of mercury. The accident location was within an active IFR advisory for cloud ceilings below 1,000 feet AGL and visibility less than 3 miles with light precipitation or mist. Forecast conditions included ceilings 1,500-2,500 feet AGL with layered clouds up to 20,000 feet, and widely scattered embedded light rain showers and isolated thunderstorms. Witnesses reported low cloud ceiling, light rain, and fog before and during the search.
Wreckage and Impact Information
The wreckage was located in hilly, heavily wooded terrain. The debris path was oriented eastward and approximately 461 feet long. The outboard half of the right wing was at the start, followed by the vertical stabilizer (423 feet west), right aileron and flap (400 feet), cockpit canopy (357 feet), inboard right wing (141 feet), and both elevators with stabilizers (89 feet). The main wreckage—consisting of the fuselage, cockpit, left wing, engine, and propeller—was in an impact crater about 3 feet deep and 10 feet wide. Damage to overhead foliage was limited, consistent with a near-vertical descent. The distribution indicated an in-flight breakup at low altitude.
All airframe structural components and flight control surfaces were accounted for. Primary structure showed severe impact damage and fragmentation. The lower firewall, cabin floor, and instrument panel were crushed upward and aft. Both wings were in multiple sections. Damage to wing and empennage load-bearing components was consistent with a positive-g maneuver. All structural failures were consistent with overload separations. Flight control cable continuity could not be established due to multiple separations, all consistent with overload.
The engine remained partially attached to the firewall; the propeller was attached to the crankshaft flange. The carburetor and induction box separated and were found in cabin wreckage; the fuel inlet screen was clean. Internal engine continuity was confirmed except for the number one cylinder due to impact damage. The engine-driven fuel pump had impact damage precluding operational testing. The left magneto was damaged; the right magneto did not spark when rotated but the ignition harness showed fraying. Spark plug electrodes exhibited normal wear. Propeller blades showed twisting, bending, and rotational scoring. Vacuum pump functional testing showed no preimpact failure. The directional gyro and attitude indicator had rotational scoring. No preimpact mechanical malfunctions or anomalies were identified.
Medical and Pathological Information
An autopsy on June 8, 2009, attributed the pilot's cause of death to multiple blunt force injuries. Toxicology tests for the pilot detected no ethanol or drugs. For the passenger, no carbon monoxide, cyanide, or drugs were found in blood, and no ethanol was detected in urine.