Accident Overview
On July 16, 2013, at about 0805 central daylight time, an experimental amateur-built Thompson Sonerai II, registration N788T, was destroyed during a collision with terrain and subsequent post-crash fire. The accident occurred after an uncontrolled descent following takeoff from Abernathy Field Airport (GZS) in Pulaski, Tennessee. The certificated private pilot/owner was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight under Part 91.
Sequence of Events
Witnesses reported to a Federal Aviation Administration (FAA) inspector that they observed the airplane come to a stop on Runway 34 with the propeller stopped after taxiing from the parking area. The pilot deplaned, walked to the front of the airplane, restarted the engine, and climbed back into the cockpit. The airplane then began its takeoff roll from that point, with approximately 2,500 feet of the 5,310-foot runway remaining. The airplane departed downwind and used the entire up-sloping runway before rotating "steeply." It traveled 2,900 feet beyond the departure end of the runway, descended "vertically," impacted a state highway in a nose-down attitude, and caught fire.
A witness traveling on the state highway noted the airplane was lower than typical departing traffic. Just before crossing the roadway, the airplane "pulled straight up…like a crop duster…about 70 –75-degree angle" before rolling left and descending straight down to ground contact. Witnesses also reported hearing the engine "sputtering" and running roughly during taxi and takeoff.
Aircraft and Pilot Information
The pilot held a private pilot certificate with a single-engine land rating. His most recent FAA third-class medical certificate was issued February 10, 2012. According to a logbook review, the pilot had logged 120 total flight hours, including 9 hours in the accident airplane, 3 hours in the preceding 90 days, and 28 hours in the previous year.
The airplane was manufactured in 1982 and purchased by the pilot/owner on March 31, 2013. Maintenance logbooks were not recovered, but an FAA inspector reported that an annual inspection was completed in May 2012. The engine was not equipped with an electric starter.
Post-Accident Examination
Photographs showed that the engine compartment, cockpit, left wing, and empennage were completely consumed by fire. The right wing was largely intact, with the leading edge crushed uniformly, consistent with a near-vertical, nose-down impact. Control continuity was established from the cockpit to all flight control surfaces. The right-side engine cylinder heads were separated by impact, exposing internal components. An engine examination was not completed due to extensive impact and fire damage.
Previous Owner's Comments
In an interview with an FAA inspector, the previous owner described the accident airplane's flight characteristics, including inherent instability, required airspeeds for stable takeoffs and landings, and stall characteristics. He stated the airplane required "lots of airspeed" to be stable and preferred 100 mph in the traffic pattern and climb for engine cooling. He noted the wing had no dihedral, lessening lateral stability, and would dip quickly in a stall, with a 1,000-foot altitude loss normal for spin recovery. The airplane also exhibited adverse yaw tendencies requiring significant rudder input. The previous owner reported entering inadvertent spins on several occasions during practice stalls.
Weather Conditions
At 1621, weather reported at GZS included clear skies, wind from 140 degrees at 3 knots, temperature 26°C, dew point 23°C, and altimeter setting 30.31 inches of mercury. Computed density altitude was 2,040 feet.