Cultural Features

CHAPTER ONE

T-6A NAVIGATION

Secondary roads include all other roads maintained for automobile traffic, including hard-

surfaced and dirt roads. They are shown as a single thin line and are selected for portrayal when

they do not cause clutter. Most often they are shown in open areas containing few checkpoints or

primary roads.

Tracks and trails are generally dirt roads not necessarily maintained for automobile traffic. They

are portrayed with a broken line and shown only in areas where few roads exist.

NOTE

Except for dual lane highways, the road classification shown on the

chart may not be a reliable indication of the visual appearance of

the road. This is particularly true of two-lane roads, which may be

encoded as primary or secondary. Therefore, roads may be

difficult to identify on any basis other than planned time of arrival.

The student should not attempt to count roads as an orientation

technique. (PROPER SCAN IS CLOCK, CHART, GROUND!)

In uncongested areas, bridges over 500 feet long are portrayed with a bridge symbol (Figure 1-8).

Bridge length may be exaggerated on the chart since the minimum length to scale on a TPC is

2000 feet between abutment ticks.

Typically, bridge symbols are shown where roads cross double line streams (streams at least 600

feet wide).

Many bridges along the flight path are not shown on the chart. Their presence is inferred by

noting the road crosses a portrayed stream. The bridges, one might infer from road crossings,

may vary widely from minor culverts to significant spans because of wide disparities among the

actual widths of single line streams. In addition, the vertical development of the bridge cannot be

determined from the symbol. Though a tall bridge appears the same on a chart as a low bridge, it

is easier to spot from a distance. Bridges are excellent fix points, but only when correctly

identified.

1-14

CHART LEGEND REVIEW