Aeronautical Charts

Chart Types

Three types of charts are used for VFR flight. These are:

Wide Area Charts(WAC) Scale 1:1,000,000 ( 1 inch = 13.7 nm)
Sectional Chart Scale 1:500,000 ( 1 inch = 6.86 nm)

VFR Terminal Charts

 Scale 1:250,000 ( 1 inch = 3.43 nm)

Most pilots use the Sectional chart. It provides good detail of topographical features, and is good for both the Student pilot as well as experienced pilot.

Since the WAC chart covers twice the area of the Sectional, pilots flying higher performance aircraft may prefer this chart. It shows less topographical features. It contains most of the electronic navigation features that are shown on the sectional charts. Both the WAC and Sectional charts show the Victor Airways.

VFR Terminal Charts are published for areas of concentrated air traffic, such as Charlotte, NYC, Los Angeles, etc. These charts show many more details. They contain landmarks often used by controllers not shown on the other chart types.

Charts show significant terrain and topographical detail, location of cities and towns, airports, navigational aids, prohibited, restricted and special use airspace, and many other symbols.

Longitude and Latitude

A system of X-Y coordinates is used to define a point on the earth's surface. These coordinates are called Meridians (longitude) and Parallels (latitude). Meridians span from the north pole to the south pole, and are measured in degrees from the PRIME MERIDIAN. It runs north and south through Greenwich, England. Measurement is either EAST or WEST from the Prime Meridian, and continues around the earth until they meet at meridian 180.The measurement, either East or West is measured in degrees, minutes and seconds. This measurement is called “Longitude”. The example dot on the diagram is at Longitude 30° 45’ W ( 30 degrees, 45 minutes West).

Meridians are not parallel. They converge at the poles, and have maximum distance between them at the equator. They represent the direction to True North. At the equator, one minute of arc longitude equals one nautical mile. The only place where 1° longitude = 1 Nm is on the equator. As one moves toward either pole, the lateral distance across one degree becomes less and less, and approaches zero at the pole. Since the earth makes one revolution of 360 degrees within 24 hours, it moves 15° in one hour.

The lines running around the earth, parallel to the equator, are called lines of parallel (or parallels). They are measured from the equator to the poles in terms called degrees of latitude. They range from 0° latitude at the equator to 90° latitude at the poles. They are termed North latitude in the Northern Hemisphere, and South latitude in the Southern Hemisphere. Unlike Meridian Lines, lines of parallel are equidistant between them (since they are parallel and do not converge). One minute of latitude equals a nautical mile.

The Latitude of the dot shown on the earth’s surface in the diagram above is defined as 35° 20’ N. Therefore, the location of the dot can be explicitly defined as 35° 20’N - 30° 45’ W.

Aeronautical charts show horizontal latitude lines and vertical longitude lines at 30 minute intervals. They are labeled near the edges of the chart, and periodically along the line. There are 30 “tick” marks between each 30 minute line, each representing one minute. The 10 minute marks are long, and the 5 minute marks are intermediate in length. One can determine latitude by locating the line below the point in question, then count upward, adding the number of tick marks from the reference line. When parallel with the point, the latitude location has been reached. (NOTE: If the latitude line is above the point in question, count the tick marks downward. Subtract them from the latitude line value. When moving North, add degrees and minutes. When moving South, subtract degrees and minutes).

To find the longitude of a point is similar. Count the tick marks either East or West from the reference longitude line to the point in question. When going in a westerly direction, add degrees and minutes. Subtract degrees and minutes when going in an easterly direction. (Note: these rules apply only in the North and Western Hemisphere.)

Three airport locations are shown below. Listed below are their ID, Latitude and Longitude. The diagram shows how to find the location of each airport. (Note: These points are shown on the Charlotte Sectional Aeronautical Chart).

SVH 35° 46’ N 80° 57’ W
LEX 35° 47 N 80° 18’ W
3N8 35° 23’ N 80° 42’ W

Note: The 36 degree North Latitude line simply has the number 36° on it at the left end of the line.

The line below it has 30’ on it. Although the number 35° does not occur on the chart, the line is 35° 30’ by inference. Charts such as this can occur on the Private Pilot Written Exam, so learn how to interpret the degree and minute legends on the charts.

To find the Lat/Lon of SVH, project a line both vertically and horizontally from the center of the airport (follow the blue dotted lines). Go to the 81° Longitude line, and count horizontally eastward by 3 minutes (3 tick marks east). When counting a number of tick marks toward the East, treat the count as a negative value. This yields a latitude = 81° 0’ - 0° 03’ = 80° 57’ W.

Likewise, go to the 35° 30’ Latitude line. Count upward 0° 16’ (16 tick marks). When counting northward, the count of the tick marks is positive) The Latitude of the airport is therefore 35° 30’ + 0°16 ‘ = 35° 46’ N. You could also have gone up to the 36° 00’ line and counted downward 14 minutes to also get a 46’ point north of Latitude 35°. In this case, you would have counted toward the South, so that the count of tick marks is negative.

In the US, when you encounter a line marked 30’ (30 minute), you must go to the next Lower Latitude Line to determine the degrees. Similarly, when a longitude line has only a 30’ (30 minute ) label, you will have to go to the right (eastward) to the next line to determine the degree of Longitude.

Time Zones

The United States lies between 67°W and 125° W. This spans 4 time zones. Meridians are useful in determining time zones. When the sun is directly above a meridian, it is noon at that meridian. To the West of that meridian, it is forenoon; to the East, it is afternoon. Since it is impractical to define 360 noon’s, the surface of the earth is divided into time zones, approximately 15° apart. However, as noted, due to local geographical and jurisdictional variations in the U. S., the actual time zone lines are irregular.

Since Greenwich, England is at the zero meridian, all time references used in flying is to the time at the zero meridian. This used to be Greenwich Mean Time. The terminology is now Coordinated Universal Time (abbreviated UTC). In aviation terminology, the word ZULU refers to UTC time, and is written with a Z suffix.

Examples: 1450Z, 0024Z, 0400Z, etc.

A conversion from local time in the US to UTC time is required for flight plans and communications with ATC. To convert local times to UTC, add the following values:

  • From EST to UTC add 5 hours.
  • From CST to UTC add 6 Hours.
  • From MST to UTC add 7 hours.
  • From PST to UTC add 8 hours.

NOTE: If the local time is Daylight Savings Time, reduce the added hours by 1 Hour (4, 5, 6, 7 respectively).

Controlled Airport Legend

CHARLOTTE
DOUGLAS INTERNATIONAL (CLT)
CT - 118.1 126.4
ATIS 121.15
749 L 100 122.95
Controlled airports with control towers (Class B, C, D) show information about the airport in BLUE lettering near the airport symbol, which is also blue. This type of data is typical of the airport information for Controlled airports with a control tower.
The data is interpreted as follows.

  • Airport Name: CHARLOTTE DOUGLAS INTERNATIONAL
  • USA Airport Identifier: CLT
  • Control Tower Frequency (CT) - 118.1 - 126.4
  • Automated Terminal Information Service (ATIS) 121.15
  • Airport Altitude - 749 feet MSL
  • L = Lighted
  • Longest Runway (100) = 10,000 feet
  • UNICOM frequency (for fuel, etc.) = 122.95

Non-Controlled Airport Legend

STATESVILE (SVH)
965 *L 50 123.05
Airports colored magenta on the charts have no control tower. The data associated with these airports is in magenta color also.
  • Airport Name: STATESVILLE
  • USA Identifier: SVH
  • Airport Altitude: 965 feet MSL
  • *L = Lighted part time (indicated by the *). Pilot controlled at other times.
  • Longest Runway (50) = 5,000 feet.
  • Common Traffic Advisory Frequency = 123.05

Plotting the Course

An instrument called a plotter is used to determine course distance and direction. It has a transparent scale and a protractor. It usually has both Sectional and WAC scales in both Nautical Mile and Statute Mile dimensions. When measuring distances from point to point, one must be careful to use the appropriate scale for the chart in use. Also, one must guard against mixing the use of the Nm and Sm scales. The scale shown on the diagram is in Nm for simplicity of the diagram.

The outer scale on the protractor is in degree divisions from 0° at the right to 180° at the left. The inner scale is from 180° at the right to 360° at the left side of the protractor.

Measuring Distance

To find the distance between two points (A and B), draw a line between the two points and place the appropriate scale along the line. Read the distance from the scale. In the example, the Sectional Nautical scale is being used. The distance is 44 Nm.

When measuring from an airport as one of the points, place the index end (zero end) at the CENTER of the airport symbol. If measuring along a Victor Airway, measure from the center dot of the VOR. Sometimes, the center of the VOR is on an airport surface. To place a VOR symbol over the airport symbol would be confusing. Therefore, the center of the VOR is represented by small white dot on the airport symbol. Measure from the white dot.

Measuring the Course

The True Course is the degrees between the direction of flight and True North measured clockwise from a Longitude Line. Shown is a course from point A to point B. The course line, A and B are shown in red. For the most accurate measurement, measure where the course line crosses a longitude line. If such an intersection does not exist between A and B, extend the course line until it does cross a longitude line.

The protractor has a small hole at the center. Place the hole over the intersection of the course line and the longitude line. The edge of the plotter on the protractor side must be along the course line. Read the true course degrees at the top of the protractor at the longitude line.

If the direction of flight is from point A to point B, read the True Course in degrees on the outer protractor scale (39° shown in red). If the direction of flight is from B to A, read the True Course in degrees on the inner protractor scale (219). NOTE: When the True Course (TC) is toward the East, use the outer scale. If the TC is toward the west, use the inner scale.

Aeronautical Chart Symbols

The following are some of the other symbols also shown on the aeronautical charts.

Airport Synbols

The symbols in Magenta are airports without a control tower. Symbols in Blue have a Control Tower.

  • Paved airport with a runway longer than 8096 feet
  • Paved airport with longest runway less than 8096 feet.
  • Un-paved airport
  • Private airport
  • Heliport
  • Sea Plane Base

Obstruction Symbols

Obstruction symbols have two elevations shown near them. The one in BOLD letters (top number) is the elevation above mean sea level (MSL). The smaller numbers enclosed in parenthesis (bottom number) indicate the height above ground level (AGL). The symbols in the left hand column are less that 1000 feet AGL. The ones on the right are above 1000 feet AGL.

Single Un-lighted Obstruction

Lighted Obstruction

Group of Obstructions

Radio Navigation Beacons

VHF OmniRange Beacon (VOR)

A VOR is indicated on the chart as a compass rose. It is oriented toward Magnetic North, as indicated by the long arrow extending from the center to the zero degree mark. An information box near the VOR Compass Rose provides information such as the radio frequency, 3 letter Identification Code, and the morse code of the identifier. There is other miscellaneous data that may be contained in the box.

There are 3 types of VOR Ranges. They are indicated at the center of the rose.

  1. Symbol A. VOR with no distance measuring capability.
  2. Symbol B. VOR-DME: A VOR with distance measuring capability.
  3. Symbol C. VORTAC: A VOR which has DME and military VORTAC capability.

For more detailed information on the VOR, see Aeronautical Information Manual.

Non-Directional Beacon (NDB)

A Non-directional Beacon is shown on the chart as a concentric series of Magenta colored dots, with the center of the circle being the location of the radio station. A magenta colored box near the circle shown the station name, the 2 or 3 letter station ID, and the morse code of the ID. This beacon is used by a navigation instrument in the aircraft called an "Automatic Direction Finder" (ADF).