How this calculator works
The ground-velocity vector is the air-velocity vector plus the wind velocity. Wind direction follows the meteorological FROM convention, while heading and course point toward travel. Crosswind determines the heading correction; along-course wind then changes ground speed. Use true bearings consistently. The direction inverse can have two valid wind bearings, so it returns a table. The heading solution uses the forward-pointing airspeed branch.
Formula
sin(WCA) = wind_speed sin(wind_from-course)/true_airspeed. Heading = course + WCA; ground_speed = true_airspeed cos(WCA) - wind_speed cos(wind_from-course).
Worked example
With a northbound course, airspeed 100 knots and a 20 knot wind from east, correction is 11.536959 degrees right. Heading is 011.536959 degrees and ground speed is 97.979590 knots.
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Frequently asked questions
Does wind direction mean where it is going?
No. Enter the direction it comes from, using the same north reference as the course.
Can every crosswind be corrected?
No. The sideways wind component cannot exceed the available true airspeed.
Why return two possible wind directions?
A known sideways component can occur with either a headwind or a tailwind component. Additional information selects the actual direction.