How to Read a Sectional Chart: The Complete Guide

What Is a Sectional Chart?

A VFR Sectional Aeronautical Chart is the primary navigation tool for pilots flying under Visual Flight Rules in the United States. Published by the FAA, these charts depict topographic features, airports, airspace boundaries, navigation aids, and obstructions — everything a pilot needs to navigate visually from one point to another.

Sectional charts use a scale of 1:500,000, which means one inch on the chart equals approximately 6.86 nautical miles on the ground. The entire United States is covered by 37 sectional charts, each named after a major city within its coverage area (e.g., the "Los Angeles" sectional or the "Chicago" sectional). Each chart covers roughly 340 by 510 nautical miles.

You can obtain current sectional charts from the FAA's official source (through AeroNav Products), digital apps like ForeFlight and SkyVector (free online viewer), or from aviation supply retailers. Charts are updated on a 56-day cycle to reflect changes in airspace, airports, and obstructions. Using an expired chart for navigation is not only unsafe — it can also be a violation of FAR 91.103, which requires pilots to become familiar with all available information for a flight.

Airport Symbols

Airports are arguably the most important features on a sectional chart. The FAA uses a systematic color and shape coding system that tells you critical information at a glance — whether an airport has a control tower, what kind of runways it has, and whether fuel and services are available.

Towered vs. Non-Towered Airports

The most fundamental distinction on a sectional chart is color. Blue airport symbols indicate a towered (controlled) airport — one with an operating control tower. You must establish two-way radio communication with the tower before entering the airspace. Magenta airport symbols indicate a non-towered (uncontrolled) airport where no control tower is operating. At these airports, pilots self-announce their position and intentions on the CTAF (Common Traffic Advisory Frequency).

Runway Surface Type

The shape of the airport symbol tells you about the runway surface. A circle with runway lines inside indicates hard-surface runways (asphalt or concrete) that are at least 1,500 feet long or longer. If the runway lines are drawn to show the actual orientation of the runways, the longest runway is at least 8,069 feet. An open circle without runway lines (just a hollow circle) indicates a hard-surface runway shorter than 1,500 feet, or a soft-surface runway (grass, dirt, gravel) of any length. These are important distinctions — landing on an unpaved surface requires different technique and aircraft capability.

Fuel and Services

Small tick marks radiating from the airport symbol indicate that fuel is available. No tick marks means no fuel services. This is critical information for cross-country flight planning. Always cross-reference with the Airport/Facility Directory (now called the Chart Supplement) for the most current fuel availability, hours of operation, and FBO contact information.

The Airport Data Box

Adjacent to each airport symbol, you will find a data block that packs a surprising amount of information into a small space. Learning to read this quickly is essential.

Military Airports

Military airports are depicted with a specific symbol pattern. The airport circle has tick marks or lines forming a specific pattern distinct from civilian airports. You will generally not land at military fields without prior permission (PPR — Prior Permission Required), but it is crucial to know where they are because of the associated airspace. Military airports may have restricted or prohibited areas nearby, and you may encounter military training traffic patterns that extend well beyond the airport boundary. Joint-use airports (shared civilian/military) are labeled accordingly and may have both military and civilian frequencies listed.

Airspace on a Sectional Chart

Understanding airspace is arguably the most complex — and most important — aspect of reading a sectional chart. The National Airspace System (NAS) is divided into classes designated A through G, each with different requirements for weather minimums, equipment, and pilot qualifications. Here is how each class appears on the chart.

Class A — The Flight Levels

Class A airspace extends from 18,000 feet MSL up to FL600 (60,000 feet). It is not depicted on sectional charts at all because sectional charts are designed for VFR operations, and Class A requires an IFR flight plan and an instrument rating. All operations in Class A must be conducted under Instrument Flight Rules. If you are flying VFR, you will never legally be in Class A airspace.

Class B — The Big Airports

Class B airspace surrounds the nation's busiest airports — think LAX, JFK, ORD, ATL. On the sectional chart, it appears as solid blue lines forming a series of concentric shelves that look like an upside-down wedding cake. Each shelf is labeled with its ceiling and floor altitudes (e.g., "100/40" means from 4,000 feet MSL up to 10,000 feet MSL).

To enter Class B airspace, you need a specific ATC clearance ("Cleared into the Class Bravo"), a two-way radio, a transponder with Mode C (altitude reporting), and at least a private pilot certificate (student pilots need a specific endorsement for certain Class B airports). The visibility minimum is 3 statute miles and you must remain clear of clouds.

Class C — Medium Airports

Class C airspace is found around airports with an operating control tower, radar approach control, and a certain level of IFR or passenger traffic. On the sectional chart, it appears as solid magenta lines. The typical shape is two concentric circles: an inner ring (5 nm radius, surface to 4,000 feet AGL) and an outer ring (10 nm radius, 1,200 feet AGL to 4,000 feet AGL).

You must establish two-way radio communication with ATC before entering Class C airspace. A transponder with Mode C is required. The key distinction from Class B: you need communication, not a specific clearance. If ATC says your callsign, you are authorized to enter.

Class D — Towered Airports

Class D airspace surrounds airports with an operating control tower that do not qualify for Class B or C. It is depicted as a dashed blue line, usually a circle with about a 4 nm radius, extending from the surface up to a designated altitude (typically 2,500 feet AGL). The ceiling is shown inside a bracketed number (e.g., "[25]" means 2,500 feet MSL).

Two-way radio communication with the tower is required before entering. If the tower closes, the Class D typically reverts to Class E or Class G airspace — check the Chart Supplement for specific tower operating hours.

Class E — Controlled But Not Towered

Class E is the most confusing airspace for student pilots because it has multiple depictions on the sectional chart, each representing a different floor altitude:

• Faded magenta line (vignette) — Class E starts at 700 feet AGL. This is the most common Class E depiction. The shading is on the side where Class E begins at 700 feet; the other side is Class G up to 1,200 feet.
• Faded blue line (vignette) — Class E starts at 1,200 feet AGL. Less common, typically used around federal airways.
• Dashed magenta line — Class E extends to the surface. This is found around non-towered airports with an instrument approach but no control tower.

Where none of these depictions exist and you are below 14,500 feet MSL, Class E generally begins at 1,200 feet AGL. Above 14,500 feet MSL, everywhere is Class E unless otherwise designated.

Class G — Uncontrolled Airspace

Class G is the "everything else" airspace. It is uncontrolled, meaning ATC has no authority or responsibility for separating aircraft. You will not see Class G explicitly drawn on the chart — it is whatever airspace is left after all other classes are accounted for. In most of the US, Class G extends from the surface up to 700 or 1,200 feet AGL (below the Class E floor). In remote areas, Class G can extend much higher. Weather minimums in Class G vary by altitude and time of day, so review FAR 91.155 carefully.

Special Use Airspace

In addition to the standard airspace classes, sectional charts depict several types of special use airspace:

Navigation Aids (NAVAIDs)

While GPS has become the primary navigation tool for most pilots, sectional charts still prominently feature ground-based navigation aids. Understanding these symbols is essential for the FAA knowledge test and for backup navigation when GPS is unavailable.

VOR / VORTAC Stations

The VOR (VHF Omnidirectional Range) is the backbone of the conventional airway system. On the sectional chart, VOR stations appear as a compass rose — a circular symbol with radial lines emanating from the center, oriented to magnetic north. A VORTAC (VOR + TACAN) looks the same but also provides DME (Distance Measuring Equipment) capabilities. A VOR-DME is similar and has a slightly different symbol (a square inside the compass rose hexagon shape).

Each VOR has an associated frequency box nearby on the chart. This box contains the VOR name, the three-letter identifier, the frequency, and the Morse code identifier. For example: "LOS ANGELES 113.6 LAX". You can practice VOR navigation with our VOR simulator.

Victor Airways

Victor airways are the "highways in the sky" for low-altitude navigation. On the sectional chart, they appear as blue lines connecting VOR stations, labeled with a "V" followed by a number (e.g., V-23). Victor airways exist from 1,200 feet AGL up to but not including 18,000 feet MSL. They are 4 nautical miles wide on each side of the centerline (8 nm total). The chart shows the airway identifier, the total distance between VORs, and any MEAs (Minimum En Route Altitudes) that apply.

NDB (Non-Directional Beacon)

NDBs are older navigation aids that transmit a signal received by the aircraft's ADF (Automatic Direction Finder). On the sectional chart, an NDB is shown as a small magenta circle with dots radiating outward. NDBs are being phased out in the US but remain important internationally and still appear on FAA exams. The frequency is shown in a nearby box, along with the identifier and Morse code.

DME Arcs and Fixes

DME (Distance Measuring Equipment) provides slant-range distance from a VORTAC or VOR-DME station. While DME arcs are more commonly associated with instrument approaches, the sectional chart shows DME distances along Victor airways. Specific fixes (waypoints) defined by a VOR radial and DME distance may be depicted with a small triangle or intersection symbol along the airway.

Terrain and Obstructions

Controlled flight into terrain (CFIT) remains one of the leading causes of fatal accidents in general aviation. Understanding how terrain and obstructions are depicted on the sectional chart is literally a matter of life and death.

Elevation Contour Lines and Color Tinting

Sectional charts use both contour lines and hypsometric tinting (color shading) to indicate terrain elevation. The color progression from low to high goes:

Contour lines connect points of equal elevation and are spaced at specific intervals (typically 200, 500, or 1,000 feet depending on the terrain). Lines spaced closely together indicate steep terrain; widely spaced lines indicate gradual slopes. Spot elevations show the exact elevation of prominent peaks or hilltops with a dot and number.

Maximum Elevation Figures (MEF)

Each latitude/longitude quadrangle on the sectional chart displays a Maximum Elevation Figure (MEF) — a large bold number representing the highest elevation within that quadrangle, including terrain and obstructions, plus a safety buffer. The MEF is read as two digits: the first in thousands and the second in hundreds. For example, "45" means 4,500 feet MSL. Flying at or above the MEF ensures terrain and obstruction clearance in that grid square — a crucial reference for VFR pilots flying in unfamiliar areas or marginal weather.

Obstruction Symbols

Man-made obstructions are a serious hazard to low-flying aircraft. The sectional chart uses specific symbols to call them out:

• Tower under 1,000 ft AGL — A small inverted "V" (triangle pointing up) with the MSL elevation on top and the AGL height in parentheses below.
• Tower 1,000 ft AGL or higher — Same symbol but with a wider base and an added "flag" appearance, making it more prominent.
• Lighted obstruction — A filled (solid) symbol. Unlighted obstructions use an open (outline-only) symbol. Lighted obstructions typically have red flashing or steady-burning lights.
• Group of obstructions — When multiple towers are clustered together, they are shown with a special grouped symbol rather than individual marks.
• High-tension power lines / cables — Depicted as a line with small perpendicular marks. Wires are particularly dangerous because they can be nearly invisible from the air. Always assume there are more wires than the chart shows.

Other Chart Features

Isogonic Lines (Magnetic Variation)

Dashed magenta lines running roughly north-south across the chart are isogonic lines. They indicate the magnetic variation — the angular difference between true north and magnetic north at that location. The line is labeled with the variation value (e.g., "12°W" means magnetic north is 12 degrees west of true north). When planning a flight, you must apply this correction to convert between true and magnetic headings. The agonic line (0° variation) runs roughly through the Great Lakes region. Use our crosswind calculator for wind correction during flight planning.

Latitude and Longitude Grid

The chart is overlaid with a grid of latitude and longitude lines, spaced at 30-minute intervals. Each full degree is labeled. These lines are essential for plotting positions, measuring distances, and identifying which quadrangle you are referencing when reading MEF figures. One degree of latitude always equals 60 nautical miles. One degree of longitude varies with latitude (60 nm at the equator, less at higher latitudes).

Visual Landmarks

Sectional charts depict cultural and natural features that are useful for visual navigation (pilotage). These include:

• Roads and highways — Major interstate highways are shown as bold red lines; smaller roads as thinner lines.
• Railroads — Depicted as lines with crosshatch marks. Railroads are excellent visual references because they are highly visible from the air and easy to follow.
• Cities and towns — Populated areas are shown with yellow tinting. Larger cities have denser yellow fill with labeled names.
• Bodies of water — Lakes, rivers, and coastlines are shown in blue. Major rivers are labeled by name. Large bodies of water are immediately recognizable and make excellent checkpoints.

Explore specific airports and their surrounding features using the Rotate airport directory.

Tips for Reading Sectional Charts

Reading a sectional chart quickly and accurately is a skill that improves with practice. Here are the techniques that experienced pilots use:

Frequently Asked Questions