When should the "calm wind" runway be used?

• A. When winds are less than 5 knots
• B. During emergency landings
• C. Only for light aircraft operations
• D. When directed by air traffic control

Answer: (A)

The appropriate use of the "calm wind" runway occurs when winds are less than 5 knots. This is because light winds do not significantly affect the aircraft's performance or handling characteristics during takeoff and landing. In such conditions, pilots can choose any runway since crosswinds or tailwinds will have minimal impact, allowing for flexibility in operations. The "calm wind" runway typically refers to the longest available runway that aligns with the prevailing conditions, providing pilots with the best option under low wind circumstances.

The other options might imply specific scenarios that do not necessarily relate to the use of a "calm wind" runway. For instance, while emergency landings may use any available runway regardless of wind conditions, the guideline specifically refers to routine operations under minimal wind. Similarly, light aircraft operations may prefer different runways based on their specific performance needs, while air traffic control may provide guidance unrelated to calm wind conditions unless required.