Example: The ATIS reports the wind as from 230° at 14 knots with runway 18 in use. In the column headed by 50° (see Figure 20) there is a box for 10 knots and a box for 20 knots. Interpolating, the headwind component will be
9.5knots and the crosswind component will be
11.5knots. Those are “approximate” because the wind when you touch down will rarely be exactly what was reported.
The Wind Side of the Slide
Directions for use of the wind side are printed on the slide (see Figure 21). It provides a graphic method of solving problems in trigonometry and displaying the answers in a very useful form.
To determine ground speed and wind correc- tion angle you must know four things: true course, true airspeed, true wind direction, and wind velocity. The winds aloft forecast provides the latter two; true course is measured directly on your sectional or WAC chart, and TAS is either converted from indi- cated airspeed in flight or taken from the airplane’s performance charts during preflight planning.
Enter the wind first. Rotate the transparent disk until the reported wind direction lines up with the TRUE INDEX. Measure up from the grommet and make a dot equal to the wind velocity. Each line equals 1 knot on the
Now rotate the transparent disk until the true course lines up with the TRUE INDEX, and move the slide up or down until the wind dot falls on the arc
28
