40 NM

18,000 ft.
1,000 ft.
NOTE:  All elevations shown are with respect to the station’s site elevation (AGL). Coverage is not available in a cone of airspace directly above the facility.
FIG GEN 3.4.3
Standard Terminal Service Volume
(See FIG GEN 3.4.4 for altitudes below 1,000 feet)

25 NM

12,000 ft.

1,000 ft.

3.1.4.5 Nondirectional Radio Beacon (NDB)  b) The ranges of NDB service volumes are shown in TBL GEN 3.4.2. The distances (radius) are the
a) NDBs are classified according to their intended
same at all altitudes.

use.

TBL GEN 3.4.1
VOR/DME/TACAN Standard Service Volumes
SSV Class Designator  Altitude and Range Boundaries 
T (Terminal) . . . . . . . . . . . .  From 1,000 feet above ground level (AGL) up to and including 12,000 feet AGL at radial distances out to 25 NM. 
L (Low Altitude) . . . . . . . .  From 1,000 feet AGL up to and including 18,000 feet AGL at radial distances out to 40 NM. 
H (High Altitude)  From 1,000 feet AGL up to and including 14,500 feet AGL at radial distances out to 40 NM. From 14,500 AGL up to and including 60,000 feet at radial distances out to 100 NM. From 18,000 feet AGL up to and including 45,000 feet AGL at radial distances out to 130 NM. 

TBL GEN 3.4.2
NDB Service Volumes
Class Distance (Radius)
Compass Locator

15 NM MH
25 NM H
50 NM* HH
75 NM

* Service ranges of individual facilities may be less than 50 nautical miles (NM). Restrictions to service volumes are first published as a Notice to Airmen and then with the alphabetical listing of the NAVAID in the A/FD.
FIG GEN 3.4.4
Service Volume Lower Edge Terminal

FIG GEN 3.4.5
Service Volume Lower Edge
Standard High and Low

1000
500

0 0 5 10 15 20 25 30 35 40 DISTANCE TO THE STATION IN NM
3.1.5 NAVAIDs with Voice
3.1.5.1 Voice equipped en route radio navigational aids are under the operational control of either an FAA Automated Flight Service Station (AFSS) or an approach control facility. The voice communication is available on some facilities. Hazardous Inflight Weather Advisory Service (HIWAS) broadcast capability is available on selected VOR sites throughout the conterminous U.S. and does not provide two-way voice communication. The avail-ability of two-way voice communication and HIWAS is indicated in the A/FD and aeronautical charts.
3.1.5.2 Unless otherwise noted on the chart, all radio navigation aids operate continuously except during shutdowns for maintenance. Hours of operation of facilities not operating continuously are annotated on charts and in the Airport/Facility Directory.
3.2 Mobile Service
3.2.1 The aeronautical stations (Airport Traffic Control Towers, Air Route Traffic Control Centers, and Flight Service Stations) maintain a continuous watch on their assigned frequencies during the published hours of service unless otherwise notified. An aircraft should normally communicate with the air.ground control radio station which exercises control in the area in which it is flying. Aircraft should maintain continuous watch on the appropriate frequency of the control station and should not abandon watch, except in an emergency, without informing the control radio station.
3.2.2 Flight Service Stations (FSSs) are allocated frequencies for different functions. For Airport Advisory Service, the pilot should contact the FSS on
123.6 MHz. Individually assigned FSS frequencies are listed in Airport/Facility Directory under the FSS entry. If you are in doubt as to what frequency to use to contact an FSS, transmit on 122.1 MHz and advise the FSS of the frequency on which you are receiving.
3.3 Fixed Service
3.3.1 Messages to be transmitted over the Aeronauti-cal Fixed Service are accepted only if they satisfy the requirements of:
3.3.1.1 ICAO Annex 10, Vol. II, Chapter 3, paragraph 3.3.
3.3.1.2 Are prepared in the form specified in Annex 10.
3.3.1.3 The text of an individual message does not exceed 200 groups.

3.3.2 General aircraft operating messages, Class B traffic, including reservation messages pertaining to flights scheduled to depart within 72 hours, shall not be acceptable for transmission over U.S. government operated telecommunications circuits except in those cases where it has been determined by the U.S. that adequate non.government facilities are not available.
3.4 Broadcast Service
3.4.1 The following meteorological broadcasts are available for the use of aircraft in flight:
3.4.1.1 LF Transcribed Weather Broadcast (TWEB).
3.4.1.2 Sub.Area Meteorological Broadcast (Vol-met).
3.4.1.3 VHF RTF Meteorological Broadcasts.
3.4.2 Full details of broadcast service are given in GEN 3.5, Meteorological Services.
　
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