At what speed will vortices from larger aircraft close to the ground move laterally?

• A. 1 to 2 knots
• B. 2 to 3 knots
• C. 4 to 5 knots
• D. 5 to 6 knots

Answer: (B)

The correct answer is relevant to the behavior and movement of wake turbulence, or vortices generated by larger aircraft during takeoff and landing. These vortices are a significant safety concern for smaller aircraft as they can lead to loss of control if encountered too closely.

When aircraft take off or land, they create rotating air masses behind them. The lateral movement of these vortices close to the ground is influenced by various factors, including wind conditions and the aircraft's size. In general, vortices close to the ground tend to move laterally at a speed between 2 to 3 knots. This speed range is important for air traffic controllers and pilots to understand because it helps in determining safe separation distances between arriving and departing aircraft, particularly when one is much larger than the other.

Understanding that vortices can disperse at these speeds is crucial for ensuring safe air traffic management and minimizing the risks of wake turbulence encounters for smaller or lighter aircraft that may be taking off or landing in the proximity of larger jet traffic.