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How to Calculate Headwind

The strength of the headwind affects flight calculations since it reduces the plane's speed and increases the amount of time needed to reach a destination. You need to be able to calculate headwind If you want to fly an airplane safely. You can calculate headwind fairly easily with a device known as an E-6B flight computer, a handheld circular slide rule.

Things You'll Need

E-6B flight computer

Instructions

- 1
  Set the wind direction. Visit the National Oceanic and Atmospheric Administration's website (See Resources) and look up the forecast for the winds aloft based on your location and the times you're going to be flying. For example, "2929+03" under the "9000" heading indicates that you will encounter winds with a bearing of 290 degrees at 29 knots at 9,000 feet.
- 2
  Rotate the true index of the E-6B (the outer circle) so it reflects what you see on the report; in this case, 290 degrees, which is almost due west (270 degrees).
- 3
  Adjust the slide so that the grommet -- the circular hole -- is over one of the heavy speed arcs. You can set it at 100, because that is easy to count from. Then mark the wind dot at 29 knots above the grommet.
- 4
  Create a flight plan at SkyVector (See Resources), and it will tell you your course. If it tells you to go at a bearing of 131 degrees, for example, rotate the true index of the E-6B to 131 degrees.
- 5
  Determine your true air speed, which is the calibrated airspeed corrected for temperature and altitude. Your pilot operating handbook will have this information.
- 6
  Align the wind dot to the speed arc of your true air speed -- say 120, for example.
- 7
  Read the ground speed under the grommet and compare it to your true air speed to determine if you have a tailwind or headwind. If, for example, your ground speed is 148, 28 knots higher than your true air speed, you have a 28-knot tailwind. If your ground speed is 110, 10 knots lower than your true air speed, you have a 10-knot headwind.

Aviation