NTSB Factual Report

On March 21, 2014, about 1600 central daylight time, an experimental amateur-built Kit Fox II, N438TT, was substantially damaged during a forced landing to a 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), Vicksburg, Mississippi. The instructional flight was conducted under the provisions of 14 Code of Federal Regulations Part 91.

According to the pilot/owner, he purchased the airplane in February of 2014 and was receiving tailwheel endorsement training. He and the flight instructor had previously flown it about 9 hours, about 2 hours each time, with no problems noted.

According to both the flight instructor and the pilot/owner, on the date of the accident, they had taken off about 1500 with light winds coming from the west. The pilot/owner had been making landings to runway 1 for about 1 hour, and the airplane was in a right climbing turn about 300 feet agl, when it suddenly "quit climbing" and "dropped." The flight instructor asked if the throttle was in; the pilot/owner responded that it was, and remembered seeing 6,500 rpm, while the flight instructor saw at least 6,000 rpm.

The flight instructor looked out his window and saw flags standing straight out to the north (wind from the south) and told the pilot/owner to turn right, with the hope of gaining some lift when the airplane headed into the wind and knowing that route 61 South would provide an option for an off-airport landing.

Once over the highway, the airplane still wouldn't climb and the flight instructor took control. There were cars on the road and power lines in the potential flight path, so the flight instructor aimed the airplane toward a large white roof. As the airplane approached the roof, it clipped a tree, then hit the roof at a steep angle.

The pilot/owner recalled seeing 6,500 rpm on the tachometer and 50 mph on the airspeed indicator as "the airplane continued dropping all the way to impact." He also thought that there could have been a wind sheer or swirl, as the airplane had "good forward motion" during the entire descent.

According to the responding Federal Aviation Administration (FAA) inspector, the airplane first impacted the flat roof about 10 feet from the edge, and slid about 30 feet, with propeller witness marks easily identified. All three fiberglass propeller blades were broken, consistent with the engine developing power at impact. The left main landing gear was collapsed and folded under the airplane. Both wings exhibited damaged, 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, and the windshield was broken. There was evidence of fuel and hydraulic fluid spillage, with absorbent on the spills. Both fuel tanks were full to the caps with fuel, and fuel could be seen in the firewall fuel filter bowl. Both carburetor butterfly plates were in the full-open position. The inspector did not report any evidence of preexisting mechanical anomalies that would have precluded normal airplane operation.

According to the flight instructor, the airplane's maximum gross weight was 950 pounds, the weight at the time of the accident was 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 degrees and 260 degrees at 8 knots. At 1635, wind was from 240 degrees, at 9, gusting to 15 knots. All observations included clear skies, 10 statute miles visibility, temperature 26 degrees C, dew point 4 degrees C.

Visible satellite imagery at 1615 did not reveal any significant weather or cloud cover.

The nearest upper air sounding, at 1900, indicated that the lowest 2,500 feet mean sea level of the atmosphere were very unstable.

According to an NTSB meteorologist, the air was so dry that thunderstorms, rain showers, and clouds would not have been expected; however, thermals would have been prominent. Differences in vegetation on the ground could have also resulted in thermals in some spots and not in others. The cooler temperatures of the river could have resulted in a slight increase in wind and some wind shear right near and around the river. Some light wind shear and turbulence could also be expected and possibly some up and downdrafts in areas where vegetation changed quickly.

Satellite mapping imagery revealed that the topography north of VKS was relatively level and included open fields mixed with housing and treed areas, and light industrial buildings.

NTSB Probable Cause

The airplane’s low-level encounter with a downdraft that maximum engine power could not overcome.