Tutorial
7. Aeronautical Charts
Aeronautical charts provide important information to the pilot. Sectional charts show topographic details, relief
features and aeronautical information of the selected area and are updated regularly. Other types of charts display
routes, airways and ground terminal locations.
The direction and distance come from a map or chart. To navigate when driving a car one uses a map with printed
routes, and you verify your position using landmarks and signs posted along the way. For air navigation your intended
course is plotted on a map or chart and your position is verified along the way with any number of interesting
methods. By the way, a chart is a map on which you plot a course.
An aeronautical chart provides pilots with a representation of a section of the Earth's surface (hence their name
"Sectional Chart"). This section shows many of the same features on a road map. These emphasize landmarks
and other special land features that would be easy for pilots to spot from the air. It delineates cities, tall
structures, geographical features and major roads. It is also color-coded. Yellow areas depict cities, green areas
indicate hills, brown is used to show mountains and magenta denotes roads. The intensity of the color corresponds
to the object's height. The greater the intensity of the color, the higher or taller the object. These charts are
updated and revised every six months. Pilots are encouraged to plot their course using the most recent and updated
chart.
The aeronautical chart is designed for convenient navigational use by pilots. It is intended to be written on and
marked up as needed by the pilot to plot the course and/or solve navigational problems such as calculations of
direction and distance.
Sectional Chart
The
scale of a "sectional" is 1/500,000 so one inch is about seven nautical
miles. It usually gives enough detail to fly by ground reference or pilotage.
A sectional shows highways and railroads, power transmission lines and television
and radio towers. It shows lakes, quarries, race tracks and other landmarks.
Sectionals also show information you cannot see on the ground such as Prohibited,
Restricted, Warning, and Alert Areas that have their own special flight rules.
Sectionals show Federal Airways commonly known as Victor Airways that are highways
in the sky connecting Very High Frequency Omnirange Stations (VOR) stations.
A sectional also shows topography or relief using contour intervals and color
differentiation. Blue indicates the lowest elevations and brown indicates the
highest. The highest obstruction in an area bounded by latitude and longitudes
are shown with a numeral for thousands of feet with another numeral as a superscript
for hundreds of feet. The highest terrain elevation is shown on the front of
the chart. Isogonic lines showing Magnetic Variation are also shown on a aeronautical
charts.
World Aeronautical Chart (WAC)
WAC charts scale is
1/1,000,000 making one inch about fourteen miles. Since WAC charts cover a larger area not as much detail is shown.
WAC charts are used for flights of long distances.
VFR Terminal Area Chart
If you plan
to fly in or near a large metropolitan area a VFR Terminal Area Chart may be available. A VFR terminal Area Chart
has everything a sectional chart has but in greater detail. The scale is 1/250,00. Open circles with points at
the top, bottom and both sides show VFR way points. Flags indicate a visual checkpoint. An air traffic controller
may tell a VFR pilot to report over the golf course for instance. The golf course will be indicated on sectionals
and VFR Terminal Area Charts with a flag icon. Small black squares indicate easily identified places on the ground.
IFR Charts
If the flight will be flown under instrument meteorological conditions, there are two types of instrument charts.
Pilots also have to file an IFR Flight Plan to fly in IMC conditions.
En
Route Low Altitude Charts are used for IFR flight planning by most propeller driven aircraft flying below the higher
flying jet aircraft. Low altitude charts show Victor Airways, minimum altitudes, distances, magnetic courses, reporting
points, and related data.
En
Route High Altitude Charts portray Jet routes, distances, time zones, special use airspace, radar jet advisory
areas, and other data. IFR flight plans are necessary for all flights above 18,000 feet.
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