At what wind speed is wind characterized as "calm"?

Wind is characterized as "calm" when its speed is less than 3 knots. This designation is important in aviation and meteorology, as it provides critical information about weather conditions affecting flight operations. When wind speeds are below this threshold, they are considered negligible, meaning there is minimal impact on aircraft performance during takeoff, landing, and taxiing.

Higher wind speed classifications indicate varying degrees of turbulence and potential challenges for aircraft maneuverability. Therefore, understanding the specific threshold for calm winds helps pilots and air traffic controllers in their decision-making processes regarding safety and efficiency during flight operations.