Sectional aeronautical charts are the foundational maps of the National Airspace System (NAS). Although drone pilots operating under 14 CFR Part 107 do not navigate to radio stations the way manned aircraft crews do, the NAVAID symbols printed on sectional charts carry critical information about controlled airspace boundaries, communication frequencies, and the underlying structure of the airspace around every flight area. Understanding what each symbol means — and what additional data is packed into the boxes and boxes of text beside each one — is a tested skill on the FAA Part 107 Aeronautical Knowledge Test and a genuine safety tool in the field.
This article walks through every common NAVAID type you will encounter on a VFR sectional chart, explains the symbol conventions, decodes the information boxes beside each station, and highlights the practical implications for remote pilots planning sUAS operations.
What Is a NAVAID?
A navigational aid (NAVAID) is any visual or electronic device — airborne or on the ground — that provides point-to-point guidance information or position data to aircraft. On a VFR sectional chart, the most common ground-based NAVAIDs are the VHF Omnidirectional Range (VOR), the Non-Directional Beacon (NDB), and various combinations or co-located equipment. Each has a distinct symbol shape, color, and associated data block that you must be able to read at a glance.
VOR Stations
The VOR is the backbone of the U.S. en route navigation system. It broadcasts a VHF radio signal (108.0–117.95 MHz) that allows equipped aircraft to determine a magnetic bearing to or from the station. On a sectional chart, a VOR is shown as a compass rose — a circle with tick marks every 30 degrees — overlaid on the geographic position of the station. The compass rose is aligned to magnetic north, which is an important distinction because sectional charts use true north for their grid lines.
Three VOR variants appear on sectionals:
- VOR only: The compass rose symbol appears alone, with no additional co-located equipment.
- VOR/DME: The compass rose is enclosed within a slightly thicker outer ring, indicating that a Distance Measuring Equipment (DME) transponder is co-located. DME allows aircraft avionics to compute slant-range distance to the station in nautical miles.
- VORTAC: A VORTAC combines a VOR with a TACAN (Tactical Air Navigation) station used by military aircraft. The symbol shows the compass rose with two small rectangular "bumps" or notches on opposite sides of the outer ring. VORTACs also provide DME service to civilian aircraft, since the civilian DME signal is derived from the military TACAN ranging component.
Reading the VOR Information Box
Next to every VOR symbol is a bracketed information box. Learning to parse it quickly is essential for the knowledge test. The box contains, in order:
- Station name — printed in bold capital letters (e.g., MEMPHIS).
- Station identifier — the two- to three-letter code (e.g., MEM), used to tune the station and displayed on cockpit instruments.
- Frequency — the VHF frequency in MHz (e.g., 117.1). This is what a pilot dials in to receive the VOR signal.
- Channel number — a TACAN channel number (e.g., Ch 118) listed only for VORTACs and VOR/DMEs; civilian pilots generally ignore this field.
- Morse code identifier — a series of dots and dashes that the station broadcasts so pilots can verify they have the correct station tuned.
Some VOR boxes include the notation "Underline" beneath the frequency, indicating that the station does not have voice capability — it transmits only the navigation signal. A box without the underline means voice broadcasts (such as ATIS, weather, or HIWAS) may be received on that frequency.
NDB — Non-Directional Beacon
The NDB transmits a low- to medium-frequency (LF/MF) signal in all directions, and an aircraft's Automatic Direction Finder (ADF) receiver points an instrument needle toward the station. On a sectional chart, an NDB is depicted as a solid magenta circle with a dot at the center, sometimes accompanied by a small dotted circle around it. The NDB does not have a compass rose overlay — that is one of the easiest ways to distinguish it from a VOR at a glance.
The NDB information box lists the station name, identifier (typically two or three letters), and frequency in kilohertz (kHz) rather than MHz, which further differentiates it from VOR data. Many NDBs are co-located at airports or serve as outer markers for instrument approaches; their locations can therefore mark the edges of certain airspace features relevant to Part 107 pilots.
Waypoints and RNAV Fixes
Modern GPS-based navigation uses RNAV waypoints — named geographic coordinates rather than physical ground stations. On a sectional chart, named waypoints that are designated intersection fixes appear as small blue or magenta triangles. They are typically identified by a five-letter pronounceable name (e.g., JIIMS or CRIED). While Part 107 pilots do not navigate using VOR radials or RNAV routes, these waypoints sometimes define the corners of special use airspace or the outer boundaries of complex Class B and Class C shelves, so knowing they exist helps you interpret airspace depictions accurately.
Why NAVAIDs Matter to Part 107 Pilots
You might wonder why a drone pilot needs to know about radio navigation stations at all. The answers are both regulatory and practical:
- Airspace boundaries: Many controlled airspace segments — especially Class B airspace floors and ceilings — are defined by radials and distances from VORs or VORTACs. Understanding the symbol tells you where to look for the associated airspace and how its boundaries are measured.
- Airport identification: VORs, VOR/DMEs, and VORTACs are almost always located at or near airports. Spotting a NAVAID symbol tells you there is likely a busy airport and associated controlled airspace nearby, which is directly relevant to your LAANC authorization or waiver needs.
- Frequency reference: Although remote pilots do not transmit on VOR frequencies, knowing that a co-located ATIS frequency can be found near a VORTAC data box helps you quickly find weather and field information if you want to listen before flying near a towered airport.
- Chart literacy: The FAA Part 107 knowledge test includes sectional chart excerpts and asks questions that require you to correctly read NAVAID information boxes to extract frequencies, identify airspace classes, or determine distances.
Key Numbers and Rules
- VOR frequency range: 108.0–117.95 MHz (VHF). Odd tenths between 108.0 and 111.95 MHz are ILS frequencies; VOR-only frequencies fall on even tenths in that band and anywhere from 112.0 to 117.95 MHz.
- NDB frequency range: 190–535 kHz (LF/MF band).
- Compass rose orientation: Aligned to magnetic north, not true north.
- Underlined frequency in VOR box: No voice transmissions available on that frequency.
- VORTAC vs. VOR/DME: Both provide DME service. VORTAC also serves military TACAN users; the symbol has two rectangular notches.
- RNAV waypoints: Named with five-letter identifiers, depicted as small triangles, define fix-based airspace boundaries.
Common Test Traps
- Confusing VOR and NDB symbols: Test questions sometimes show a symbol and ask you to identify the station type. Remember — the compass rose = VOR family; solid dot/circle = NDB. If there is no compass rose, it is not a VOR.
- Misreading the frequency units: VOR frequencies are in MHz; NDB frequencies are in kHz. Mixing these up on the test is a common error, especially when a question lists a frequency like "385" and asks what type of station it is — 385 kHz is clearly an NDB.
- Assuming all VORTACs are near airports: Most are, but some VORTACs are located in open terrain far from any airport. Do not infer an airport exists simply because a VORTAC symbol appears.
- Ignoring the underline convention: A question may ask which frequency can be used to receive a voice weather broadcast. If the VOR frequency is underlined, that station cannot be used for voice — you must look elsewhere.
- Treating compass rose tick marks as current magnetic variation: The rose is aligned to magnetic north for navigation, but it does not display the local magnetic variation value. Magnetic variation (isogonic lines) is shown separately on the chart as dashed lines with degree values.
Mastering NAVAID symbols is one of the highest-leverage investments you can make in your sectional chart reading skills. Each symbol is a compact data package: station type, frequency, identifier, and voice capability are all encoded in a few square centimeters of chart space. Once you can parse these boxes quickly and connect them to the airspace structure around your planned flight area, you will be reading sectional charts the way experienced pilots do — confidently, accurately, and safely.