Accident Overview
On March 21, 2014, at about 1600 central daylight time, an experimental amateur-built Kit Fox II, registration N438TT, was substantially damaged during a forced landing onto the roof of an industrial supply company in Vicksburg, Mississippi. The flight instructor and the sport pilot/owner under instruction were seriously injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the local flight from Vicksburg Municipal Airport (VKS). The instructional flight was conducted under 14 Code of Federal Regulations Part 91.
Flight History
According to the pilot/owner, he had purchased the airplane in February 2014 and was receiving tailwheel endorsement training. He and the flight instructor had previously flown it about 9 hours, in sessions of about 2 hours each, with no problems noted. On the accident day, they had taken off around 1500 with light winds from the west. The pilot/owner had been making landings to runway 1 for about one hour.
Accident Sequence
While in a right climbing turn about 300 feet above ground level, the airplane suddenly "quit climbing" and "dropped." The flight instructor asked if the throttle was in; the pilot/owner responded that it was, noting 6,500 rpm, while the flight instructor saw at least 6,000 rpm. The instructor observed flags standing straight out to the north (indicating wind from the south) and directed the pilot to turn right, hoping to gain lift into the wind and knowing that Route 61 South provided an off-airport landing option. Once over the highway, the airplane still would not climb, and the flight instructor took control. With cars on the road and power lines in the flight path, the instructor aimed for a large white roof. As the airplane approached, it clipped a tree and then struck the roof at a steep angle. The pilot/owner later recalled seeing 6,500 rpm and 50 mph on the airspeed indicator as the airplane descended to impact. He speculated that wind shear or swirl might have been present, given the airplane's "good forward motion" throughout the descent.
Post-Accident Examination
According to the responding Federal Aviation Administration inspector, the airplane first impacted the flat roof about 10 feet from the edge and slid about 30 feet, with propeller witness marks clearly visible. All three fiberglass propeller blades were broken, consistent with the engine developing power at impact. The left main landing gear had collapsed and folded under the airplane. Both wings exhibited damage, including spar damage. The fuselage was twisted, and both flap/ailerons were damaged. The engine mount was broken and twisted, as was the cockpit area, with the bulk of the damage around the left seat; the windshield was broken. There was evidence of fuel and hydraulic fluid spillage, with absorbent applied. Both fuel tanks were full to the caps, and fuel was visible in the firewall fuel filter bowl. Both carburetor butterfly plates were in the full-open position. The inspector reported no evidence of preexisting mechanical anomalies that would have precluded normal airplane operation.
Weather and Environment
The flight instructor reported that the airplane's maximum gross weight was 950 pounds, with the accident weight at 900 pounds, and the Rotax 582 engine generated a maximum of 65 horsepower. Weather recorded at VKS at 1555 included wind from 220 degrees true at 12 knots. At 1615, wind was from 230 degrees, varying between 170 and 260 degrees, at 8 knots. At 1635, wind was from 240 degrees at 9 knots, gusting to 15 knots. All observations noted clear skies, 10 statute miles visibility, temperature 26°C, and dew point 4°C. Visible satellite imagery at 1615 showed no significant weather or cloud cover. The nearest upper air sounding, taken at 1900, indicated that the lowest 2,500 feet mean sea level of the atmosphere were very unstable. An NTSB meteorologist noted that the air was so dry that thunderstorms, rain showers, and clouds were not expected, but thermals would have been prominent. Differences in vegetation could have resulted in thermals in some spots and not others. The cooler temperatures of the river could have caused a slight increase in wind and some wind shear near the river. Some light wind shear and turbulence could also be expected, possibly with up and downdrafts in areas where vegetation changed quickly. Satellite mapping imagery revealed that the topography north of VKS was relatively level, including open fields mixed with housing and treed areas, as well as light industrial buildings.