Tips to read aeronautical charts

I’ve always been fascinated by how pilots navigate the skies; isn’t that puzzling? Drivers use road maps, and signs along the way guide them in the right direction. But what about pilots in the air? They don’t have any indications telling them where to go or what obstacles they should avoid, and getting lost is out of the question. As a result, they rely on an aeronautical chart to navigate.

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An aeronautical chart is a map used to help in aircraft navigation. Pilots can establish their position, safe altitude, optimum route to a destination, navigation aids along the way, alternate landing areas in the event of an in-flight emergency, and other helpful information such as radio frequencies and airspace borders using it and other technologies. There are maps for every landmass on the planet, as well as long-distance maps for trans-oceanic travel.

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Visual charts are classified according to their scale which is directly proportional to the size of the area covered by one map.

  1. World Aeronautical Charts (WACs) are a form of aeronautical charts used for navigation by pilots of medium-speed aircraft and aircraft flying at high altitudes. They have a scale of 1:1,000,000 and cover a huge area. These graphs are similar to sectional graphs and use the same symbols. However, because of the smaller scale, it has less information. It displays topographic information, airports, and radio navigational aids. They’re useful for strategic flight planning, as they provide you with a bird’s-eye view of the whole flight region. These charts are updated annually, except for a few Alaskan charts and the Mexican/Caribbean charts, which are updated every two years.
  2. Sectional charts are printed on both sides of the map and have a scale of 1:500,000. They cover a total area of around 340×340 miles. It is aimed to be used in visual flight rules air navigation (VFR). It shows topographical elements (such as terrain levels), ground features (such as rivers, dams, bridges, and buildings), and other ground objects that pilots may find useful (airports, beacons, landmarks, etc.). Not only those but also airspace classifications, ground-based navigation aids, radio frequencies, longitude and latitude, navigation waypoints, and navigation routes are displayed on the sectional charts. These charts are updated every six months.
  3. VFR Terminal area charts are designed with a scale and coverage appropriate for a large airport’s general surroundings (1:250,000).
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Fixed-Base Operators (FBOs), internet supply providers, and catalogs of aeronautical gear all sell aeronautical charts. They are also available to view on the FAA’s website. Because aeronautical information is always changing, pilots should double-check the effective dates on each chart and publication. It is critical to always use current editions and remove obsolete charts and publications to avoid risk.

These are some quick tips to begin reading the sectional charts

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First tip

Every location on the planet has a latitude and longitude coordinate system that is defined by an imaginary grid pattern. To easily calculate longitude and latitude, we must first know the equator’s and prime meridian’s locations. The prime meridian is a line that goes from the North Pole to the South pole and passes through Greenwich, New England. It is the zero longitude and serves as a basis for all other longitudes. The equator, which is perpendicular to the prime meridian, acts as zero latitudes and is the primary measurement for all other latitudes.

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There are two popular methods for determining latitude and longitude.
First, there is the historical technique, which uses the degrees, minutes, and seconds system (1 degree equals 60 minutes, and 1 minute equals 60 seconds). Second, there’s the modern GPSecimal notation. And, of course, switching between the two methods is simple. The map is divided into four quadrants. A quadrant is a 30-minute latitude and 30-minute longitude area defined by a boundary. When pilots are identifying specified but large areas in sectional charts, quadrant identifiers serve as rapid referencing.

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Second tip

One of the most important points in that chart is the airports. Of course, there are numerous types of them, therefore sectional charts differentiate them based on whether they have a control tower, a hard-surfaced runway, or fuel availability. Military airports are easily identified by abbreviations such as AAF (Army Air Field), NAS (Naval Air Station), and NAV (Naval Air Facility), among others.
To find out what information is available for a specific airport, check the set of letters and numbers that accompany each airport symbol.
According to an agreement with the International Civil Aviation Organization, each airport’s name is represented by an abbreviation (ICAO).
The dark blue circle with the letter ‘C’ indicates that the airport employs the Common Traffic Advisory Frequency (CTAF), which allows passing aircraft to self-announce their location and intentions. This means that, even though the airport has a control tower, it is only operational part-time.

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Credit : Pilotinstitute
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Third tip

The terrain and obstacles
aside from areas of interest, sectional charts help pilots avoid obstructions and navigate across continuously shifting terrain. Contour lines or a shaded relief map are the most common topographical indicators, and either of these can be used as the sectional chart’s foundation map. The maximum elevation of any topography or man-made features in a quadrant is represented by the MEF (Maximum Elevation Figure).

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Credit: Pilotinstitute
Credit: Pilotinstitute
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Fourth tip

Controlled vs. uncontrolled vs. special use airspace are the three types of airspace that are represented by symbols.
The airspace where Air Traffic Control (ATC) services are provided is referred to as controlled airspace. The uncontrolled airspace, also known as Class G airspace, does not have ATC regulatory service due to low air traffic volume. Special-use airspace is an area where air traffic limitations may apply for a variety of reasons that aren’t necessarily related to conventional air traffic activity.

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Credit: Studentpilotnews
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Controlled airspace is classified into 5 classes

Class A: exists between 18,000 and 60,000 feet in altitude. Commercial airlines often use this airspace for long-haul flights.

Class B: represented as a solid blue line that encompasses the nation’s busiest airports, as well as important air travel hubs in major cities. Because these airports have some of the biggest aviation traffic volumes in the country, you can expect Class B airspace to be the most extensive. The geometry of Class B airspace varies from airport to airport, although it usually takes the shape of an upside-down cake, with the biggest layers at the highest altitudes.

Class C: represented as solid magenta line. There is a slight difference between Class B and C. However Class C has different symbols as it is applied for small and less busy airports but both still have the same upside-down cake shape.

Class D: represented as blue dashed, which is for the smallest airport in the nation.


Class E: refers to all other controlled airspace zones that aren’t covered by the previous categories.

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The special use airspaces

Prohibited Area : which are tagged P-XXX and represented as solid blue lines with hash marks. They are usually established for national security and welfare reasons.

Restricted Areas: are tagged R-XXX and are represented by solid blue lines with hash marks. Drone flight is not fully restricted in restricted areas, however, a drone pilot will need to obtain permission from the proper regulatory agency.

Warning Areas: are tagged W-XXX. Drone operators are allowed to fly their drones in warning areas without prior permission, but they should exercise extreme caution.

Alert Areas: are tagged A-XXX are represented as solid magenta lines with hash marks. Because of flight training exercises and air shows, aviation traffic above alert areas is predicted to be exceptionally heavy. Another characteristic of aviation traffic in alert areas is that it might behave in surprising and unique ways.

Military Operation Areas (MOA): are represented as solid magenta lines with hash marks and are labeled in a manner that is very hard to miss. Military activities It could be anything from a training exercise to a packed operation. Drones should not be flown in MOAs since they are extremely risky.

Military Training Route (MTR): represented as arrow symbols in sectional charts, Military Training Routes (MTRs) are designated by a prefix of VR (visual rules) or IR (instrument rules) and a number. The number can be three digits, indicating that military operations are being carried out at altitudes greater than 1500 feet.

Temporary Flight Restriction: These are proclaimed in places where there are temporary risks or security concerns, causing uncontrolled aircraft flights to be restricted. The most common reasons for TFRs are the movement of the President or Vice-President, the presence of distinguished foreign dignitaries, large-scale entertainment or sporting events, disaster assistance, or emergency response.

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Credit: FAA

Those were some easy tips and indications to begin understanding the sectional chart. And you may also check this user guide for all the symbols used: https://ticc.tamu.edu/Documents/OtherInfo/VFR_Symbols.pdf
So don’t worry, your pilot won’t get lost because he’s acquainted with charts and tools that are just similar to our roadmaps.

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Sources

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