How Do You Use A Graphic Flight Computer To Find Ground Speed And True Heading?
• Align the wind direction under the “True Index” mark by rotating the azimuth plate. If the winds are from 330° at 20 knots, align 330 under the true index. • Align the grid so the center grommet is over one of the heavy lines. It doesn’t matter which line is used at this point. • Plot the wind speed and direction Mark the wind speed by counting up from the center grommet. Each light line represents two knots. Mark a dot or an X in pencil on the 20 knot line (two heavy lines above the center grommet). This is the wind dot. • Rotate the azimuth plate until your desired course (true course) is aligned under the True Index mark. Use 175° for this example. • Slide the grid until the wind dot is over your true airspeed. In this example, the true airspeed is 120 knots. • Read ground speed and wind correction angle Read ground speed under the grommet. Ground speed is the speed of the aircraft over the ground and in this example is 138 knots. • Find the wind correction angle (WCA) by checking
