Figure C-3 Contour Lines

LOW-LEVEL AND TACTICAL FORMATION

APPENDIX C

Figure C-3 Contour Lines

Spot Elevations. Spot elevations are the heights of particular points of terrain above an

established datum plane, usually at sea level. Spot elevations are identified on the ONC, TPC,

and JOG. Accuracy to within 100 feet is indicated by black numbers preceded by a dot, which

indicates the exact location of the elevation (.000). Approximate elevations are shown in black

numbers preceded by a small x (x0000). Undetermined locations are indicated by omission of

the point locator (0000). Critical elevations (mountain peaks) are indicated by heavy black

numbers and dots (.0000).

Maximum Elevation Figure (MEF). The MEF is based on the highest point, natural or

man-made, within a given grid square (Figure C-4). The MEF is determined by adding a 200-

foot safety margin, plus a vertical accuracy factor, to the highest point in the grid square, and

then rounding up to the next 100-foot increment. If you fly at the MEF, you should have at least

200 feet of obstruction clearance.

Cultural Features. All man-made structures appearing on a chart are called cultural

features. The following three factors govern the amount of detail: the scale of the chart, use of

the chart, and geographical area covered. Population centers, roads, railroads, towers, power

lines, dams, and bridges are some of the many kinds of cultural features portrayed on

aeronautical charts. The true representative size and shape of larger cities and towns are shown.

Standardized coded symbols and type sizes are used to represent the smaller population centers.

Although most symbols denoting cultural features are keyed in the legend, some are self-

explanatory. Examine cultural features with caution; if the chart is several years old, man-made

features have certainly changed.

NAVIGATIONAL CHARTS C-5