explanation of vfr terms

1 VFR AERONAUTICAL CHARTS

EXPLANATION OF VFR TERMS AND SYMBOLS

The discussions and examples in this section are based on the Sectional Aeronautical Chart (Sectional). Sec-tionals include the most current data and are at a scale (1:500,000) most beneficial to pilots flying under Visual FlightRules. A pilot should have little difficulty in reading these charts which are, in many respects, similar to automobileroad maps. Each chart is named for a major city within its area of coverage.

The chart legend lists various aeronautical symbols as well as information concerning terrain and contourelevations. You may identify aeronautical, topographical, and obstruction symbols (such as radio and television tow-ers) by referring to the legend. Many landmarks which can be easily recognized from the air, such as stadiums,pumping stations, refineries, etc., are identified by brief descriptions adjacent to small black squares marking theirexact locations . Oil wells are shown by small open circles . Water, oil and gas tanks are shown by smallblack circles and labeled accordingly, if known. The scale of an item may be increased to make it easier toread on the chart.

NACO charts are prepared in accordance with specifications of the Interagency Air Cartographic Committee(IACC) and are approved by representatives of the Federal Aviation Administration (FAA) and the Department ofDefense (DoD).

TERRAIN AND OBSTRUCTIONS

The elevation and configuration of the Earth'ssurface are certainly of prime importance to pilots. Car-tographers devote a great deal of attention to showingrelief and obstruction data in a clear and concise manner.Five different techniques are used: contour lines, shadedrelief, color tints, obstruction symbols, and MaximumElevation Figures (MEF).

1. Contour lines are lines con-necting points on the Earth of equalelevation. On Sectionals, basic con-tours are spaced at 500' intervals.Intermediate contours may also be shown at 250' inter-vals in moderately level or gently rolling areas. Occasion-ally, auxiliary contours at 50, 100, 125, or 150' intervalsmay be used to portray smaller relief features in areas ofrelatively low relief. The pattern of these lines and theirspacing gives the pilot a visual concept of the terrain.Widely spaced contours represent gentle slopes, whileclosely spaced contours represent steep slopes.

2. Shaded relief is adepiction of how the terrainmight appear from the air. Thecartographer shades theareas that would appear inshadow if illuminated by al ight from the northwest.Studies have indicated thatour visual perception has been conditioned to this view.

3. Color tints, also referred to ashypsotints, are used to depict bands of ele-vation reletive to sea level. These colorsrange from light green for the lowest eleva-tions to dark brown for the higher eleva-tions.

4. Obstruction symbols are used todepict man-made vertical features thatmay affect the National Airspace System.NACO maintains a database of over118,000 obstacles in the United States,Canada, the Caribbean and Mexico. Eachobstacle is evaluated by cartographersbased on charting specifications before it isadded to the visual charts. When the posi-tion or elevation of an obstacle is unveri-fied, it is marked UC (under construction orreported but not verified).

The data in the Digital Obstacle File (DOF) is col-lected and disseminated as part of NACO’s responsibilityfor depicting the National Airspace System.

Source data on terrain and obstructions is some-times not complete or accurate enough for use in aero-nautical publications; for example, a reported obstructionmay be submitted with insufficient detail for determiningthe obstruction's position and elevation. Such cases areidentified by NACO and investigated by the FAA FlightEdit program.

The FAA Flight Edit crew conducts data verifica-tion missions, visually verifying cultural and topographicfeatures and reviewing all obstacle data. Charts are gen-erally flight-checked every three years. This reviewincludes checking for obstructions that may have beenconstructed, altered, or dismantled without proper notifi-cation.

1000

2000

3000

7000

5000

9000

12000

-228

19633

VFR AERONAUTICAL CHARTS 2

Generally, only man-made structures extendingmore than 200' above ground level (AGL) are charted.Objects 200' or less are charted only if they are consid-ered hazardous obstructions; for example, an obstruc-tion is much higher than the surrounding terrain or verynear an airport. Examples of features considered hazard-ous obstacles to low level flight are smokestacks, tanks,factories, lookout towers, and antennas.

Obstacles less than 1000' AGL are shown by the

symbol . Obstacles 1000' AGL and higher are

shown by the symbol . Man-made features which areused by FAA Air Traffic Control as checkpoints may berepresented with pictorial symbols shown in black withthe required elevation data in blue.

The elevation of the top of theobstacle above mean sea level (MSL) andthe height of the structure AGL are shownwhen known or when they can be reliablydetermined by the cartographer. TheAGL height is shown in parentheses below the MSL ele-vation. In extremely congested areas the AGL values maybe omitted to avoid confusion.

Obstacles are portrayed wherever possible. Butsince legibility would be impaired if all obstacles withincity complexes or within high density groups of obstacleswere portrayed, only the highest obstacle in an area is

shown using , the group obstacle symbol.Obstacles under construction are indicated by

the letters immediately adjacent to the symbol. Ifavailable, the AGL height of the obstruction is shown inparentheses; for example, . Obstacles with high-in tens i t y s t robe l i gh t i ng sys tems a re shown

as:5. The Maximum Elevation Figure (MEF) repre-

sents the highest elevation, including terrain and othervertical obstacles (towers, trees, etc.), within a quadrant.A quadrant on Sectionals is the area bounded by tickedlines dividing each 30 minutes of latitude and each 30minutes of longitude. MEF figures are depicted to thenearest 100' value. The last two digits of the number arenot shown. In this example the MEF represents 12,500'.

MEFs are shown over land masses as well as over openwater areas containing man-made obstacles such as oilrigs.

In the determination of MEFs, extreme care isexercised to calculate the values based on the existing

elevation data shown on source material. Cartographersuse the following procedure to calculate MEFs:

When a man-made obstacle is more than 200'above the highest terrain within the quadrant:

1. Determine the elevation of the top of theobstacle above MSL.

2. Add the possible vertical error of the sourcematerial to the above figure (100' or 1/2 con-tour interval when interval on source exceeds200'. U.S. Geological Survey QuadrangleMaps with contour intervals as small as 10'are normally used).

3. Round the resultant figure up to the nexthigher hundred foot level.

Example: Elevation of obstacle top (MSL) = 2424Possible vertical error + 100

equals 2524Raise to the following 100 foot level 2600

Maximum Elevation Figure

When a natural terrain feature or natural vertical obstacle(e.g. a tree) is the highest feature within the quadrangle.:

1. Determine the elevation of the feature.2. Add the possible vertical error of the source

to the above figure (100' or 1/2 the contourinterval when interval on source exceeds200').

3. Add a 200' allowance for natural or man-made obstacles which are not portrayedbecause they are below the minimum heightat which the chart specifications require theirportrayal.

4. Round the figure up to the next higherhundred foot level.

Example: Elevation of obstacle top (MSL) = 3450Possible vertical error + 100Obstacle Allowance 200

equals 3750Raise to the following 100 foot level 3800

Maximum Elevation Figure

Pilots should be aware that while the MEF isbased on the best information available to the cartogra-pher, the figures are not verified by field surveys. Also,users should consult the Aeronautical Chart Bulletin inthe A/FD or NACO website to ensure that your chart hasthe latest MEF data available.

RADIO AIDS TO NAVIGATION

On visual charts, information about radio aids tonavigation is boxed, as illustrated. Duplication of data isavoided. When two or more radio aids in a general areahave the same name with different frequencies, TACANchannel numbers, or identification letters, and no misin-terpretation can result, the name of the radio aid may beindicated only once within the identification box. VHF/


UHF radio aids to navigation names and identificationboxes (shown in blue) take precedence. Only those itemsthat are different (e.g., frequency, Morse Code) arerepeated in the box in the appropriate color. The choiceof separate or combined boxes is made in each case onthe basis of economy of space and clear identification ofthe radio aids.

Radio aids to navigation located on an airportdepicted by the pattern symbol may not always beshown by the appropriate symbol. A small open circleindicates the NAVAID location when co-located with anairport symbol. The type of radio aid to navigation maybe indicated by letter identification; e.g., VOR, VORTAC,or VOR-DME, positioned on and breaking the top line ofthe identification box.

AIRPORTS

Airports in the following categories are charted asindicated (additional symbols are shown later in this Sec-tion).

Public use airports:

Hard-surfaced runways greater than 8069' orsome multiple runways less than 8069'

Hard-surfaced runways 1500' to 8069'

Other than hard-surfaced runways

Seaplane bases

Military airports:

Other than hard-surfaced runways

Hard-surfaced runways are depicted the sameas public-use airports.U.S. military airports are identified by abbrevia-tions such as AAF (Army Air Field), AFB (Air ForceBase), MCAS (Marine Corps Air Station), NAS(Naval Air Station), NAF (Naval Air Facility), NAASNaval Auxiliary Air Station), etc. Canadian militaryairports are identified by the abbreviation DND(Department of National Defense).

Services available:Tick marks around the basic airport symbol indi-cate that fuel is available and the airport is tendedduring normal working hours. (Normal workinghours are Monday through Friday 10:00 A.M. to4:00 P.M. local time.)

Other airports with or without services:

Airports are plotted in their true geographic posi-tion unless the symbol conflicts with a radio aid to navi-gation (navaid) at the same location. In such cases, theairport symbol will be displaced, but the relationshipbetween the airport and the navaid will be retained.

Airports are identified by their designated name.Generic parts of long airport names (such as "airport”,"field” or "municipal") and the first names of persons arecommonly omitted unless they are needed to distinguishone airport from another with a similar name.

The figure at right illus-trates the coded data that isprovided along with the airportname. The elevation of an air-port is the highest point on theusable portion of the landingareas. Runway length is thelength of the longest active run-way including displaced thresh-olds and excluding overruns.Runway length is shown to thenearest 100', using 70 as thedivision point; a runway 8070' in length is charted as 81,while a runway 8069' in length is charted as 80.

Airports with Control Towers (CT), and theirrelated information, are shown in blue. All other airports,

{


and their related information, are shown in magenta (red-dish purple).

The symbol indicates that runway lights are onduring hours of darkness. A indicates that the pilotmust consult the Airport/Facility Directory (A/FD) todetermine runway lighting limitations, such as: availableon request (by radio call, letter, phone, etc), part-timelighting or pilot/airport controlled lighting. Lighting codesrefer to runway edge lights. The lighted runway may notbe the longest runway available, and may not be lightedfull length. A detailed description of airport and air navi-gation lighting aids available at each airport can be foundin the A/FD. When information is lacking, the respectivecharacter is replaced by a dash. The symbol indicatesthe existence of a rotating or flashing airport beaconoperating continuously sunset to sunrise. The Aeronauti-cal Information Manual (AIM) thoroughly explains thetypes and uses of airport lighting aids.

CONTROLLED AIRSPACE

Controlled airspace consists of those areaswhere some or all aircraft may be subject to air trafficcontrol, such as Class A, Class B, Class C, Class D,Class E Surface (SFC) and Class E Airspace.

Class A Airspace

within the United Statesextends from 18,000' up to 60,000' MSL. While visualcharts do not depict Class A, it is important to note itsexistence.

Class B Airspace

is shown in abbreviated formon the World Aeronautical Chart (WAC). The SectionalAeronautical Chart (Sectional) and Terminal Area Chart(TAC) show Class B in greater detail. The MSL ceiling andfloor altitudes of each sector are shown in solid blue fig-

ures with the last two digits omitted: Radials and

arcs used to define Class B are prominently shown onTACs. Detailed rules and requirements associated withthe particular Class B are shown. The name by which

the Class B is identified is shown as forexample.

Class C Airspace

is shown in abbreviated formon WACs. Sectionals and TACs show Class C in greaterdetail.

The MSL ceiling and floor altitudes of each sectorare shown in solid magenta figures with the last two dig-

its eliminated: . The following figures identify a sec-

tor that extends from the surface to the base of the Class

B: . The name by which the Class C is identified is

shown as: . Separate notes, enclosedin magenta boxes, give the approach control frequenciesto be used by arriving VFR aircraft to establish two-wayradio communication before entering the Class C (gener-ally within 20 NM):

Class D Airspace

is symbolized by a bluedashed line. Class D operating less than continuous isindicated by the following note: . Ceilings

of Class D are shown as follows: . A minus in frontof the figure is used to indicate "from surface to but notincluding .... .”

Class E Surface (SFC) Airspace

is symbolizedby a magenta dashed line. Class E SFC operating lessthan continuous is indicated by the following note:

Class E Airspace

ex is ts at 1200' aboveground level unless desig-nated otherwise. The lat-eral and vertical limits of allClass E up to but not including 18,000' are shown bynarrow bands of vignette on Sectionals and TACs. Con-trolled airspace floors of 700' above the ground aredefined by a magenta vignette; floors other than 700'that abut uncontrolled airspace (Class G) are defined bya blue vignette; differing floors greater than 700' above

the ground are annotated by a symbol and a

number indicating the floor. If the ceiling is less than18,000' MSL, the value (prefixed by the word "ceiling") isshown along the limits of the controlled airspace. Theselimits are shown with the same symbol indicated above.

UNCONTROLLED AIRSPACE

Class G Airspace

within the United Statesextends up to 14,500' MSL. At and above this altitude isClass E, excluding the airspace less than 1500' abovethe terrain and certain special use airspace areas.

SPECIAL USE AIRSPACE

Special use airspace confines certain flight activ-ities and restricts entry, or cautions other aircraft operat-


ing within specific boundaries. Except for ControlledFiring Areas, special use airspace areas are depicted onvisual aeronautical charts. Controlled Firing Areas are notcharted because their activities are suspended immedi-ately when spotter aircraft, radar, or ground lookout posi-tions indicate an aircraft might be approaching the area.Nonparticipating aircraft are not required to change theirflight paths. Special use airspace areas are shown in theirentirety (within the limits of the chart), even when theyoverlap, adjoin, or when an area is designated withinanother area. The areas are identified by type and identi-fying name or number, positioned either within or imme-diately adjacent to the area.

OTHER AIRSPACE AREAS

Mode C Required Airspace

(from the surface to10,000' MSL) within 30 NM radius of the primary air-port(s) for which a Class B is designated, is depicted by

a solid magenta line . Mode C is required

but not depicted for operations within and above allClass C up to 10,000' MSL. Enroute Mode C require-ments (at and above 10,000' MSL except in airspace atand below 2500' AGL) are not depicted. See FAR 91.215and the AIM.

FAR 93

Airports and heliportswhere Federal Aviation Regulation (FAR93) special air traffic rules and airporttraffic patterns apply are shown by"boxing" the airport name.

FAR 91

Airports where fixed wing special visualflight rules operations are prohibited (FAR 91) are shownwith the type "NO SVFR" above the airport name.

National Security Areas

indicated with a brokenmagenta line and

Special Federal AviationRegulations (SFAR) Areas

indicated with the followingsymbol: , consist of airspace with definedvertical and lateral dimensions established at locationswhere there is a requirement for increased security andsafety of ground facilities. Pilots are requested to volun-tarily avoid flying through these depicted areas. Whennecessary, flight may be temporarily prohibited.

Temporary Flight Restriction (TFR) AreasRelating to National Security

are indicated with a bro-ken blue line . A Temporary Flight Restriction

(TFR) is a type of Notices to Airmen (NOTAM). A TFRdefines an area restricted to air travel due to a hazardouscondition, a special event, or a general warning for theentire airspace. The text of the actual TFR contains thefine points of the restriction. It is important to note thatonly TFRs relating to National Security are charted.

Air Defense Identification Zones (ADIZs)

aresymbolized using the ADIZ symbol: . Asdefined in 14 CFR Part 99, an ADIZ is an area in whichthe ready identification, location, and control of all aircraftis required in the interest of national security. ADIZboundaries include Alaska, Canada and the ContiguousU.S.

Due to federal security agencies’ concerns aboutunidentified VFR aircraft flying too close to the nation’scapital, in early 2003 the FAA adapted the ADIZ conceptto address these concerns and issued a Flight Data Cen-ter (FDC) NOTAM that designated this airspace as theWashington DC Metropolitan Air Defense IdentificationZone (DC ADIZ).

The Washington DC Flight Restricted Zone(FRZ) Relating to National Security

is depicted usingthe Prohibited/Restricted/Warning Area symbology

and is located within the DC ADIZ. It isdefined as the airspace within approximately a 13 to15NM radius of the KDCA VOR/DME. Additional require-ments are levied upon operators requesting access tooperate inside the National Capitol Region.

Terminal Radar Service Areas (TRSAs)

areshown in their entirety, symbolized by a screened blackoutline of the entire area including the various sectorswithin the area .

The outer limit of the entire TRSA is a continuousscreened black line. The various sectors within the TRSAare symbolized by slightly narrower screened black lines.

Each sector altitude is identified in solid blackcolor by the MSL ceiling and floor values of the respec-tive sector, eliminating the last two digits. A leader line isused when the altitude values must be positioned out-side the respective sectors because of space limitations.The TRSA name is shown near the north position of theTRSA as follows: . Associated frequen-cies are listed in a table on the chart border.

Military Training Routes (MTRs)

are shown onSectionals and TACs. They are identified by the routedesignator: . Route designatorsare shown in solid black on the route centerline, posi-tioned along the route for continuity. The designator IR orVR is not repeated when two or more routes are estab-lished over the same airspace, e.g., IR201-205-227.Routes numbered 001 to 099 are shown as IR1 or VR99,eliminating the initial zeros. Direction of flight along theroute is indicated by small arrowheads adjacent to and inconjunction with each route designator.


The following note appears on Sectionals andTACs covering the conterminous United States.

There are IFR (IR) and VFR (VR) routes as follows:Route identification:a. Routes at or below 1500' AGL (with no seg-

ment above 1500') are identified by four-digitnumbers; e.g., VR1007, etc. These routes aregenerally developed for flight under VisualFlight Rules.

b. Routes above 1500' AGL (some segments ofthese routes may be below 1500') are identi-fied by three-digit or less numbers; e.g., IR21,VR302, etc. These routes are developed forflight under Instrument Flight Rules.

MTRs can vary in width from 4 to 16 miles.Detailed route width information is available in the FlightInformation Publication (FLIP) AP/1B (a DoD publication),or in the Digital Aeronautical Chart Supplement (DACS)produced by NACO.

Special Military Activity

areas are indicated onthe Sectionals by a boxed note in black type. The notecontains radio frequency information for obtaining areaactivity status.

TERMINAL AREA CHART (TAC) COVERAGE

TAC coverage is shown on appropriate Section-als by a 1/4" masked line as indicated below. Within thisarea, pilots should use TACs which provide greater detailand clarity of information. A note to this effect appearsnear the masked boundary line.

INSET COVERAGE

Inset coverage is shown on appropriate Section-als by a 1/8" masked line as indicated below. A note tothis effect appears near the masked boundary line.

CHART TABULATIONS

Airport Tower Communications

are provided ina columnized tabulation for all tower-controlled airportsthat appear on the respective chart. Airport names arelisted alphabetically. If the airport is military, the type ofairfield, e.g., AAF, AFB, NAS, is shown after the airfieldname. In addition to the airport name, tower operatinghours, primary VHF/UHF local Control Tower (CT),Ground Control (GND CON), and Automatic TerminalInformation Service (ATIS) frequencies, when available,will be given. An asterisk (*) indicates that the part-timetower frequency is remoted to a collocated full-time FSSfor use as Local Airport Advisory (LAA) when the tower isclosed. Airport Surveillance Radar (ASR) and/or Preci-sion Approach Radar (PAR) procedures are listed whenavailable.

Approach Control Communications

are pro-vided in a columnized tabulation listing Class B, Class C,Terminal Radar Service Areas (TRSA) and SelectedRadar Facilities when available. Primary VHF/UHF fre-quencies are provided for each facility. Sectorizationoccurs when more than one frequency exists and/or isapproach direction dependent. Availability of servicehours is also provided.

Special Use Airspace (SUA)

information iscomprised of Prohibited, Restricted, Alert, and WarningAreas. They are presented in blue and listed numericallyfor U.S. and other countries. Restricted, Danger andAdvisory Areas for Canada are tabulated separately inblue. A tabulation of Military Operations Areas (MOA) thatappear on the chart are presented in magenta and listedalphabetically. All are supplemented with altitude, time ofuse and the controlling agency/contact facility, and itsfrequency, when available. The controlling agency will beshown when the contact facility and frequency data isunavailable.


AirportName

Hours of Operation(local time)

Frequencies (VHF/UHF)

Runway dependent

Approachdirection

dependent

Radar InstrumentApproach available

AirspaceName

VHF/UHF

VHF/UHF

{ {

{{

{VHF

UHF{

{ Sectors forVHF and UHF traffic

local time

Sunrise to Sunset

Frequencies (VHF/UHF)

Radar Approach

Control

RestrictedDanger

Advisory

{

NOT FOR NAVIGATIONNNNNNNNTIOIOIOOO

GANAVIG

OOOORORRRR NR NFFTTTOOTOTOTTTTT FFFFFF

NNNNNONONOOOOOTOTOTNNNNNNONONONOOOOO

explanation of vfr terms

Documents