The wind correction angle (WCA) is how many degrees you turn the nose into the wind so the airplane tracks your planned course instead of drifting off it. It comes from the wind triangle, along with your ground speed: your true course and true airspeed worked against the forecast wind. Use the calculator below to get heading, ground speed, time and fuel for any leg, then learn the math and the E6B method behind it.
Part of our Navigation and Flight Planning guide. For the whole trip, from route to fuel reserve, see how to plan a cross-country flight.
The wind triangle in plain English
An airplane flies through a mass of air, and that whole mass moves over the ground with the wind. If you point the nose straight down your course line in a crosswind, the air carries you sideways and you drift off course. The fix is to point the nose a little upwind, so the sideways push and your slight angle cancel out and your track over the ground stays on the line you drew on the sectional chart.
The wind triangle has three sides, and you always know two of them before the flight:
- True course and ground speed: where you want to go over the ground, and how fast you will actually get there.
- True heading and true airspeed: where the nose points, and how fast the airplane moves through the air.
- Wind: the direction it blows from and its speed, from the winds aloft forecast.
You know your true course from the chart and your true airspeed from the POH or a flight computer, and the forecast gives you the wind. Solving the triangle gives you the rest: the wind correction angle, your true heading, and your ground speed.
How to calculate wind correction angle and ground speed
The formula
- Find the wind angle: the wind direction minus your true course.
- Find the crosswind component: wind speed times the sine of the wind angle.
- Find the wind correction angle: the angle whose sine is the crosswind component divided by your true airspeed.
- Apply it: add the angle to your true course when the wind is from the right, subtract it when the wind is from the left. The result is your true heading.
- Find ground speed: true airspeed times the cosine of the wind correction angle, minus the headwind component (wind speed times the cosine of the wind angle). A tailwind makes that component negative, so it adds speed.
The crosswind math is the same as the runway version on our crosswind calculator page; the only difference is that you measure the angle from your course instead of the runway.
A mental math shortcut
For a quick check, the most drift you can get (a wind straight across your course) is about the wind speed times 60, divided by your true airspeed, in degrees. A 20 knot wind at 110 knots gives about 11 degrees. Then scale it with the clock-face fractions: a wind 15 degrees off your course needs about a quarter of that, 30 degrees about half, 45 degrees about three quarters, and 60 degrees or more nearly all of it. For ground speed, subtract the headwind component (or add the tailwind component) from your true airspeed.
A worked example
You are planning a 120 nautical mile leg with a true course of 090. Your POH gives a true airspeed of 110 knots at cruise, burning 8.5 gallons per hour. The winds aloft forecast for your altitude is 030 at 20 knots, and the magnetic variation on your chart is 5 degrees west. The calculator above opens with this example:
- The wind is 60 degrees left of your course, so the crosswind is about 17 knots from the left and the headwind about 10 knots.
- Wind correction angle: about 9 degrees left, so the true heading is 081.
- Magnetic heading: 081 plus 5 degrees west variation is 086.
- Ground speed: about 99 knots, so the leg takes about 1 hour 13 minutes and burns about 10.3 gallons before your reserve.
The shortcut agrees: 11 degrees of maximum drift times nearly full for a wind 60 degrees off the nose is about 10 degrees, and 110 knots minus a 10 knot headwind component is about 100 knots.
From true heading to compass heading
Work the wind triangle entirely in true, then convert to what you will actually steer. The FAA’s Pilot’s Handbook of Aeronautical Knowledge lays out the order:
| Step | Apply | Result |
|---|---|---|
| True course (from the chart) | Wind correction angle: add if the wind is from the right, subtract if from the left | True heading |
| True heading | Variation from the isogonic lines: east is least (subtract), west is best (add) | Magnetic heading |
| Magnetic heading | Deviation from the compass correction card in the airplane | Compass heading |
Your navigation log has a column for each of these, so writing them down in order keeps you from applying variation twice or in the wrong direction.
Where the winds come from: true or magnetic?
This is the most common wind triangle mistake. Winds aloft forecasts, METARs and TAFs give the wind direction relative to true north, which is exactly what the wind triangle needs. Winds you hear on ATIS or from a control tower are magnetic, because they relate to runway headings. For en route planning, use the winds aloft forecast for the altitude closest to your planned cruise, and interpolate between levels when you are in between. The forecast leaves out winds for any level within 1,500 feet of the station’s elevation. Our guide to reading METARs and TAFs covers the surface reports.
Plan the whole trip at once: PilotMall’s free VFR navigation log works the wind triangle for every leg and keeps running totals of time and fuel, ready to print for your kneeboard.
How to solve the wind triangle on an E6B
The wind side of the manual E6B solves the same problem with a sliding grid. The most common method uses a pencil mark called the wind dot:
- Rotate the compass rose until the wind direction is under the true index.
- Slide the grid so the center grommet sits on a convenient speed line, and mark the wind dot straight up from the grommet, a distance equal to the wind speed.
- Rotate the compass rose until your true course is under the true index.
- Slide the grid until the wind dot sits on your true airspeed line.
- Read the ground speed under the grommet. Count the drift lines between the centerline and the wind dot for the wind correction angle: add it if the dot is right of center, subtract it if left.
Work the example above and you should see the wind dot about 9 degrees left of center, with the grommet near 99 knots. The ASA CX-3 electronic flight computer solves the same triangle from typed entries. Our step-by-step guide to using an E6B and CX-3 has more practice problems, and the E6B guide helps you choose one.
What you'll need
The plotter and flight computers you use to plan every cross-country leg, from PilotMall.com.
Frequently asked questions
What is the wind correction angle?
The wind correction angle is the difference between your true course and the true heading you must fly to stay on that course in a crosswind. You turn the nose into the wind: add the angle when the wind is from the right and subtract it when the wind is from the left.
How do you calculate the wind correction angle?
Find the crosswind component (wind speed times the sine of the angle between the wind and your course), divide it by your true airspeed, and take the angle whose sine is that number. For a quick estimate, use wind speed times 60 divided by true airspeed for a direct crosswind, and less for winds closer to the nose or tail.
Do you add or subtract the wind correction angle?
Add it to your true course when the wind is from the right of your course, and subtract it when the wind is from the left, so the nose always points slightly into the wind.
Are winds aloft forecasts true or magnetic?
True. Winds aloft forecasts, METARs and TAFs give the wind direction relative to true north. Winds from ATIS and the control tower are magnetic because they relate to runway headings.
How do you find ground speed from true airspeed and wind?
Solve the wind triangle. Ground speed is your true airspeed reduced by the headwind component, or increased by the tailwind component, with a small extra loss from crabbing into a crosswind. The calculator on this page, an E6B wind side, or a CX-3 gives it directly.
Do I apply variation before or after the wind correction angle?
After. Work the wind triangle in true, with your true course and the true winds, to get true heading. Then apply variation to get magnetic heading, and deviation from the compass card to get compass heading.