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Wind triangle calculator

Aviation

What heading and ground speed do I need with this wind?

The heading to fly, the wind correction angle and the ground speed for a course and wind, with the leg time, fuel and a drawn triangle.

°

kt

°

kt

Leg, fuel and units

NM

Optional: gives the time for the leg.

L/h

Optional: with a distance, gives the fuel for the leg.

°

Optional: east as plus, west as minus, from the chart. Gives the magnetic heading.

Heading to fly (true)

082°

Wind correction 8° left · ground speed 96 kt

North up, to scale: fly 082° at 110 kt in the wind 040° 20 kt, and the aircraft moves along 090° at 96 kt.

Your leg

Wind correction angle
8° left
Ground speed
96 kt

What this means

  • Fly 082° to make good 090°: the nose points 8° left of the course, into the wind, and the aircraft crabs along the line.
  • The wind slows you down: the ground speed is 14 kt below the true airspeed.

The wind on your course

Headwind
13 kt
Crosswind
15 kt from the left
True heading
082°
True course
090°

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The heading to fly, the wind correction angle and the ground speed for a course and wind, with the leg time, fuel and a drawn triangle.

How to use

  1. Enter the true course from your chart and your true airspeed.
  2. Enter the wind direction and speed from the forecast for your cruising altitude.
  3. Read the heading to fly, the wind correction angle and the ground speed; the triangle shows how they fit together.
  4. Optionally, add the leg distance and your fuel burn for the time and fuel, and the magnetic variation for the magnetic heading.

Ground speed into a headwind

Headwind (kt)Ground speed (kt)
0120
10110
20100
3090
4080

TAS 120 kt, course 090° true and wind directly from ahead.

How it works

An aircraft moves through the air, and the air itself moves with the wind. To travel along the line on the chart, the pilot points the nose a little into the wind, so the aircraft crabs along the line. The wind triangle has three sides: the air vector (heading and true airspeed), the wind, and the ground vector (track and ground speed). This is the wind side of the E6B flight computer.

If the course is CRS, the wind blows from WD at W and the true airspeed is TAS, the wind correction angle is WCA = asin(W × sin(WD − CRS) / TAS), the heading is CRS + WCA, and the ground speed is GS = TAS × cos WCA − W × cos(WD − CRS). Example: course 090°, TAS 110 kt, wind from 040° at 20 kt. WCA = asin(20 × sin(−50°) / 110) ≈ −8°, so fly 082°, and GS = 110 × cos 8° − 20 × cos 50° ≈ 96 kt. A 60 nmi leg then takes 60 / 96 h ≈ 38 minutes. Sources: FAA Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), chapter 16; Ed Williams, Aviation Formulary.

Forecast winds are true, so the course and heading here are true too; subtract an east variation (add a west one) for the magnetic heading on the compass. The answer is only as good as the forecast wind, and the fuel figure has no taxi, climb or reserve fuel. For learning, simulators and curiosity, not for flight planning or navigation.

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Frequently asked questions

Why does the wind slow me down even when it blows from the side?

To hold the course, part of the airspeed goes into fighting the crosswind, so even a pure crosswind lowers the ground speed a little.

Should I use the true or the magnetic course?

Use the true course with a forecast wind, which is true. Turn the result into a magnetic heading with the variation: subtract east, add west.

What if the wind is too strong?

If the crosswind is larger than your airspeed, no heading holds the course, and the calculator says so. Slow aircraft such as microlights and paragliders meet this in strong winds.

Is the ground speed the same as on my GPS?

It should be close if the wind forecast is right. Comparing the two in flight is a good way to see the real wind.

Is wind direction where the wind comes from or goes to?

Enter where it comes from. A wind from 090° blows from east to west, so it is a headwind on an eastbound course of 090°.

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