What is crosswind in aviation terms and why does it matter for runway selection?

• A. Crosswind is the wind component perpendicular to the runway direction and can influence runway selection.
• B. Crosswind is the wind component parallel to the runway direction.
• C. Crosswind is the vertical wind component.
• D. Crosswind is gusts across the entire airfield.

Answer: (A)

Crosswind is the wind component that blows perpendicular to the runway centerline, creating a sideways push on the aircraft during takeoff and landing. This sideways force causes drift, makes it harder to keep the wings level and the aircraft aligned with the runway, and can affect rollout distance and control. Because of that, choosing a runway with a smaller crosswind component helps maintain better handling within an aircraft’s limits and reduces the need for corrective techniques like crabbing or a wing-low sideslip.

The crosswind component is found by projecting the wind onto a line perpendicular to the runway. The part of the wind that acts along the runway (headwind or tailwind) is separate and influences airspeed and landing distance, but not the lateral control issue characterized by crosswind. If the wind direction is close to the runway heading, the crosswind is small; if it’s off by a larger angle, the crosswind becomes larger.