History of Flight
On April 6, 2011, about 0905 mountain daylight time, an Aviat Aircraft, Inc., A-1C-180, registration N28WY, sustained substantial damage when it impacted terrain about 11 miles east of Laramie, Wyoming. The commercial pilot, the sole occupant, was fatally injured. The airplane was registered to and operated by Alpine Aviation of Alpine, Wyoming, under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the cross-country positioning flight, which originated from Fort Collins, Colorado, about 0800 with an intended destination of Alpine.
According to the pilot of a lead airplane flying a similar aircraft, both were repositioning two Aviat A-1C-180 airplanes from Florida to Alpine. The lead pilot stated that prior to departure, they reviewed the weather and were confident about the flight, though some areas might have marginal VFR conditions. After an uneventful departure from Fort Collins, the flight stayed close to Interstate 80. Shortly after departure, they encountered light rain but no ice. As both airplanes approached a mountain pass east of Laramie, they encountered light snow with a cloud ceiling of about 1,200 feet above ground level and 3 to 4 miles visibility. The lead pilot estimated that around this time, he heard a transmission from the accident pilot saying he was "on the edge of a stall." No further radio transmissions were received. The lead pilot reported no evidence of icing on his airplane or abnormal flight characteristics. A witness on Interstate 80 at milepost 336 observed two airplanes flying northwest at low altitude, noting that the trailing airplane was shaking abnormally.
Pilot and Aircraft Information
The pilot, age 73, held a commercial pilot certificate with airplane single-engine land, single-engine sea, and instrument ratings. A second-class airman medical certificate was issued on March 9, 2011, with no limitations. The pilot reported 4,500 total flight hours on his most recent medical application; his logbook showed 4,307.2 hours as of March 28, 2011.
The Aviat A-1C-180, serial number 310, was manufactured in 2010. It was a two-seat, high-wing, fixed-gear airplane powered by a Lycoming O-360-A1P engine rated at 180 horsepower, with a Hartzell two-blade adjustable-pitch propeller. It was equipped with 8.50x6 tires and an Airglass cargo pod. The airplane's logbook records were not located during the investigation.
Meteorological Conditions
A National Weather Service Surface Analysis Chart at 0900 depicted a low pressure center in central Colorado, with calm and light winds in the region. At 0853, Laramie Regional Airport reported wind from 230 degrees at 7 knots, visibility 10 miles or more, overcast ceiling at 4,900 feet, temperature 2°C, dew point -6°C, and altimeter 29.89 inches of mercury. A Wyoming Department of Transportation weather station (WY28), about 1 mile northwest of the accident site at an elevation of approximately 8,570 feet, recorded at 0905 moderate snow, temperature 25°F, dew point 24.6°F, 97% relative humidity, and visibility 0.78 miles. Information on data quality assurance and instrument operation was not obtained. A North American Mesoscale model sounding indicated no potential for icing below about 11,000 feet, and the troposphere below 500 hPa was mostly stable or conditionally unstable. A Terminal Aerodrome Forecast for Laramie issued at 0530 forecasted for 0600–1000 wind from 310 degrees at 12 knots, visibility 4 miles, light snow, scattered clouds at 2,000 feet, and overcast ceiling at 4,000 feet.
Wreckage and Examination
The airplane came to rest on its left side about 300 feet north of Interstate 80. All major structural components were present; the right wing was partially separated, and the engine was crushed aft into the fuselage. Wreckage was recovered for further examination. Examination of the recovered airframe revealed that the left and right wings were separated from the fuselage by recovery personnel. The fuselage was mostly intact aft of the cabin area. The flap handle was consistent with 30 degrees of flaps, elevator trim slightly nose down, fuel selector valve ON, carburetor heat handle extended (ON), and throttle handle full forward. Battery power applied to the stall warning horn produced an audible tone. Flight control continuity was established throughout. The left wing exhibited leading edge crushing from root to tip, mostly on the upper edge. The right wing showed leading edge crushing from root to tip, with crushing oriented at about a 20-degree angle from just inboard of the landing light outboard. The stall warning switch was intact and undamaged; electrical continuity was established. The vertical stabilizer and rudder were intact.
The engine and accessories were examined. The gascolator was disassembled and found free of debris. All four cylinders were examined internally with a borescope and were unremarkable. Rotational continuity was established, and thumb compression and suction were noted on all cylinders. Both magnetos produced spark on all terminals. The carburetor was intact; throttle and mixture arms moved freely; fuel screen and float bowl were clear. The propeller was separated from the crankshaft; both blades remained attached. One blade showed leading-edge polishing near the tip and chord-wise scratches; the other showed polishing and scratches from mid-span to tip. Both blades exhibited a slight aft bend near the root. No evidence of preimpact mechanical malfunction was found.
Loose items from the airframe (luggage, clothes, flight bag, brochures, signs, chairs) weighed about 231 pounds.
Medical and Pathological Information
An autopsy conducted by the Albany County Coroner's Office on April 6, 2011, reported the cause of death as "rapid deceleration tear of the aorta." Toxicological tests performed by the FAA's Civil Aeromedical Institute found desmethylsertraline (0.27 ug/mL in blood), quinine, sertraline (0.107 ug/mL in blood), and sertraline in the liver. Quinine is an antimalarial also used for leg cramps; at usual doses it has no significant effect. Sertraline (Zoloft) is an antidepressant in the SSRI class; its therapeutic range is 0.010–0.200 ug/mL and carries an FDA warning about impairing ability for hazardous tasks. The pilot's primary physician, who was also his aviation medical examiner, reported being unaware of the pilot's medication use.
GPS Data
A Garmin GPSmap 396 and Garmin GPSmap 696 were recovered. The 396 contained no data from the accident flight. The 696 yielded data showing the flight track from Fort Collins via Interstate 25 to Interstate 80, then west/northwest paralleling the interstate. The airplane climbed to about 8,600 feet, then began a descent in the last 3 minutes 57 seconds of data. Groundspeed increased from 78 to 85 knots for 44 seconds following the descent start, then decreased to about 53 knots over the next 2 minutes 56 seconds. The last recorded data point was 0.3 miles south of the accident site at an altitude of 8,533 feet.