Wind Correction Angle Calculator
Calculate the wind correction angle (crab angle) needed to fly or sail a straight course in crosswind conditions.
When wind blows across your path of travel, you must aim into the wind to maintain a straight course over the ground. The angle you aim away from your desired track is the Wind Correction Angle (WCA), also called the crab angle.
Formula: WCA = arcsin(wind speed × sin(wind angle) / airspeed or vessel speed)
Where wind angle is measured from your desired track direction (0° = headwind, 90° = direct crosswind, 180° = tailwind).
Worked example (aviation):
- True airspeed: 120 knots
- Wind: 15 knots from 270°, flying course 360° (north)
- Wind angle relative to course: 90° (direct crosswind from the left)
- WCA = arcsin(15 × sin(90°) / 120) = arcsin(0.125) = 7.2°
- Heading to steer: 360° − 7.2° = 352.8° (turn into the wind)
Worked example (sailing / kayaking):
- Vessel speed through water: 5 knots
- Cross-current: 1.5 knots at 90°
- WCA = arcsin(1.5 / 5) = 17.5° — aim 17.5° upstream
Effective speed after correction: Ground speed = sqrt(airspeed² − (wind × sin(wind angle))²) ± wind × cos(wind angle)
Pilot rule of thumb: WCA ≈ (crosswind component / airspeed) × 60 For small angles (under 15°) this approximation is accurate within 1°.