Which statement about helicopter ground taxiing compared with hover taxiing is true?

Which statement about helicopter ground taxiing compared with hover taxiing is true?

• A. Increases noise
• B. Minimizes air turbulence
• C. Higher emissions
• D. Reduces visibility

Answer: (B)

Rotor wash and lift management differ between modes. When a helicopter is taxiing on the ground, the weight is supported by the landing gear, so the rotor doesn’t have to produce as much lift. You can use a lower collective and still move, which reduces the downward air velocity and the strength of the rotor downwash. With weaker downwash, the air around the helicopter remains steadier and less turbulent. In hover taxiing, the rotor must generate enough lift to keep the helicopter off the ground while moving, which creates stronger downward and outward air movement and more turbulence in the surrounding air. Because ground taxiing lessens the rotor-induced air disturbances, it minimizes air turbulence. The other factors—noise, emissions, and visibility—can vary with power and conditions and aren’t the primary difference between these two taxiing modes.

Rotor wash and lift management differ between modes. When a helicopter is taxiing on the ground, the weight is supported by the landing gear, so the rotor doesn’t have to produce as much lift. You can use a lower collective and still move, which reduces the downward air velocity and the strength of the rotor downwash. With weaker downwash, the air around the helicopter remains steadier and less turbulent. In hover taxiing, the rotor must generate enough lift to keep the helicopter off the ground while moving, which creates stronger downward and outward air movement and more turbulence in the surrounding air. Because ground taxiing lessens the rotor-induced air disturbances, it minimizes air turbulence. The other factors—noise, emissions, and visibility—can vary with power and conditions and aren’t the primary difference between these two taxiing modes.