If wind is 18 knots from the left at 90° to the runway, what is the crosswind component?

If wind is 18 knots from the left at 90° to the runway, what is the crosswind component?

• A. 10 knots
• B. 12 knots
• C. 18 knots
• D. 20 knots

Answer: (C)

Crosswind is the portion of wind that pushes the aircraft sideways relative to the runway. When wind comes from the left at 90 degrees to the runway, it is exactly perpendicular to the runway centerline, so the crosswind component equals the full wind speed. Using crosswind = wind speed × sin(angle between wind and runway), with angle = 90°, sin(90°) = 1, giving 18 knots. There is no headwind component here (wind speed × cos(90°) = 0). So the crosswind component is 18 knots. The other values would occur at different angles where sin is less than 1.

Crosswind is the portion of wind that pushes the aircraft sideways relative to the runway. When wind comes from the left at 90 degrees to the runway, it is exactly perpendicular to the runway centerline, so the crosswind component equals the full wind speed. Using crosswind = wind speed × sin(angle between wind and runway), with angle = 90°, sin(90°) = 1, giving 18 knots. There is no headwind component here (wind speed × cos(90°) = 0). So the crosswind component is 18 knots. The other values would occur at different angles where sin is less than 1.