Wind correction angle and groundspeed calculator

The wind triangle: what to steer, and how fast you will actually go.

How it works

sin(WCA) = (wind speed ÷ TAS) × sin(wind angle), and groundspeed = TAS × cos(WCA) − wind speed × cos(wind angle), where the wind angle is measured from your course to the direction the wind is coming from.

True, magnetic, compass

This works in true throughout, because winds aloft forecasts are true. To fly it, subtract easterly variation or add westerly to get magnetic, then apply the aircraft's deviation card. Variation is not a rounding error — it exceeds 20° in the western US and far more in Alaska.

What it does not model

One wind for the whole leg. If the forecast changes materially along the route, split the leg at that point and run it twice — averaging the winds produces a fuel figure that was never correct at any moment of the flight.

Live: the strongest sustained winds right now

Sustained wind, not gusts. At light-aircraft true airspeeds several of these would demand a wind correction angle big enough to be uncomfortable — try one above.

Other calculators

For planning and study, not for operational use. Aircraft performance comes from your POH, not from a generic formula.