Crosswind component

Split the wind into two parts: one blowing across the runway, one along it. Both come from the angle between the wind and the runway heading (TP 1102).

• Crosswind = wind × sin(angle), the sideways push you hold off with rudder and aileron; it sets the demonstrated-crosswind limit. Sine grows with the angle: the more off the nose, the bigger.
• Headwind or tailwind = wind × cos(angle), the along-runway part that sets your ground roll. Cosine is largest straight down the runway and falls to zero at 90° across.

Rule of thumb (rounds the sine curve): 30° off ≈ ½ crosswind, 45° ≈ 0.7, 60° ≈ 0.85, straight across (90°) is all crosswind.

Report winds in knots. The TP 1102 crosswind graph also carries a mph scale, so if a wind is given in mph convert first (1 kt ≈ 1.15 mph) before reading a component in knots.

Trap: using cos where you need sin gives you the headwind, not the crosswind.

Practice