2. Search and Scan in Flat Terrain (Horizontal Scanning). Search from the horizon to 20
degrees above the horizon by moving your eyes in short movements across the sky, working up and
across. Continue the pattern below the horizon to detect aircraft contour flying. This method of
scanning is shown in figure 15.
Figure 15. Horizontal Scanning
3. Search and Scan in Hilly Terrain (Vertical Scanning). Search the sky using the horizon as
a starting point and prominent terrain features as reference points by moving your eyes in short
movements up the sky, then back down, continuing the movement across the terrain. You should
scan in the same pattern to 20 degrees below the horizon to detect aircraft contour flying.
This method of scanning is shown in figure 16.
Figure 16. Vertical Scanning