N4335T

At the time of the accident, simultaneous operations were being conducted at the airport. Airplanes were in left traffic for landing on runway 20, and military helicopters were in right traffic landing to a midfield helipad on the west (right) side of the runway. According to the flight instructor (CFI) in the accident airplane, the student pilot completed three touch-and-go landings and proceeded around the pattern for a fourth landing. During the landing the airplane approached the runway as a helicopter "suddenly lifted to a hover." Several witness statements and security video revealed that the 2,150-pound airplane followed behind an airplane that landed on the runway, and passed abeam an 18,000-pound Army utility helicopter on final approach to the helipad, before it banked sharply to the right and impacted terrain. Post-accident examination of the airplane by an FAA inspector revealed partial separation of the right wing and substantial damage to the fuselage. The CFI reported there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.

According to the FAA's Aeronautical Information Manual, section 7-3-7:

In a slow hover taxi or stationary hover near the surface, helicopter main rotor(s) generate down wash producing high velocity outwash vortices to a distance approximately three times the diameter of the rotor. When rotor downwash hits the surface, the resulting outwash vortices have behavioral characteristics similar to wing tip vortices produced by fixed wing aircraft. However, the vortex circulation is outward, upward, around, and away from the main rotor(s) in all directions. Pilots of small aircraft should avoid operating within three rotor diameters of any helicopter in a slow hover taxi or stationary hover. In forward flight, departing or landing helicopters produce a pair of strong, high-speed trailing vortices similar to wing tip vortices of larger fixed wing aircraft. Pilots of small aircraft should use caution when operating behind or crossing behind landing and departing helicopters.