Updated November 2026 · free, works in your browser
Show the formula
WCA = asin( WS × sin(WD − TC) / TAS )
Heading = TC + WCA
Groundspeed = TAS × cos(WCA) − WS × cos(WD − TC)
TC = course, TAS = true airspeed, WD = direction the wind blows from, WS = wind speed. A positive WCA means correct to the right. Use true or magnetic for both course and wind; the heading comes out in the same reference.
To find the heading to fly and your groundspeed in a crosswind, enter your course, true airspeed, and the wind direction and speed. The calculator solves the classic E6B wind triangle: it returns the wind correction angle, the heading that holds your course, and the groundspeed you can expect. Results update as you type.
How to use
- Enter your desired course in degrees (0 to 360).
- Enter your true airspeed and choose knots, mph or km/h.
- Enter the direction the wind is blowing from, in degrees, and the wind speed in the same unit.
- Read the heading to fly, the wind correction angle (R means turn right of course, L left) and the groundspeed.
- Use the headwind/tailwind and crosswind components to check runway or leg conditions, or copy a link to share the result.
Keep the reference consistent: if the course and wind are magnetic, the heading is magnetic too. If both are true, the heading is true.
How it is calculated
The calculator uses the standard wind triangle relations:
WCA = asin( WS × sin(WD − TC) / TAS )
Heading = TC + WCA
Groundspeed = TAS × cos(WCA) − WS × cos(WD − TC)
TC is the true course, TAS the true airspeed, WD the direction the wind blows from and WS the wind speed. The term WS × sin(WD − TC) is the crosswind component, and WS × cos(WD − TC) is the headwind component (negative values mean a tailwind). These are the same relations a mechanical E6B computer solves graphically, as described in standard pilot training texts on navigation.
A quick mental check is the share of the wind that acts as crosswind, depending on the angle between the wind and your course:
| Angle between wind and course | Share of wind as crosswind |
|---|---|
| 30° | about 50% |
| 45° | about 70% |
| 60° | about 87% |
| 90° | 100% |
Frequently asked questions
What is the wind correction angle?
It is the angle between your course over the ground and the heading you point the nose. You turn into the wind by this amount so that the aircraft tracks along the intended course rather than drifting downwind.
Is the wind direction the direction it blows from or to?
Aviation winds are reported as the direction the wind blows from. Enter it that way. A wind from 270° pushes the aircraft toward the east.
Why is my groundspeed lower even in a pure crosswind?
When you crab into a crosswind, part of your airspeed is used to hold the course against the drift, so you fly slightly slower along the track. The effect is small for light winds and grows as the crosswind approaches your airspeed.
Why does the calculator say the course cannot be held?
If the crosswind component equals or exceeds your true airspeed, no heading can keep you on the course. The same applies when the headwind is so strong that groundspeed would be zero or negative.
Can I use indicated airspeed?
No. The wind triangle needs true airspeed, because the wind moves the air mass relative to the ground. Convert indicated airspeed to true airspeed first, using altitude and temperature.
This tool is a planning aid. Always verify numbers against your flight computer, current weather and approved flight planning sources.
From wind triangle to trip plan
Groundspeed decides how long a leg takes, and that decides when you land. On a cross-country trip, a strong headwind or a weather delay can turn a day trip into an overnight stop. It helps to look at accommodation near your destination airport ahead of time, so a change of plans only costs you a booking rather than a scramble.
Other tools
- Crosswind Component CalculatorEnter the runway heading, wind direction and wind speed to get the crosswind and headwind or tailwind components.
- Density Altitude CalculatorEnter field elevation, temperature and altimeter setting to get pressure altitude and density altitude.
- Airport Runway Length CheckerSearch a Vermont airport and see its longest runway, surface type and whether your required distance fits.
This is an independent guide. It is not affiliated with Vermont Agency of Transportation.