Aeronautical Information Manual (AIM), page 68

Index   67 -- Page 68 -- 69


1-1-11. NAVAID Identifier Removal During

During periods of routine or emergency maintenance,
coded identification (or code and voice, where
applicable) is removed from certain FAA NAVAIDs.
Removal of identification serves as a warning to
pilots that the facility is officially off the air for
tune-up or repair and may be unreliable even though
intermittent or constant signals are received.
During periods of maintenance VHF ranges may radiate
a T-E-S-T code (- D DDD -).


DO NOT attempt to fly a procedure that is NOTAMed out
of service even if the identification is present. In certain

cases, the identification may be transmitted for short
periods as part of the testing.

1-1-12. NAVAIDs with Voice

a. Voice equipped en route radio navigational aids
are under the operational control of either a Flight
Service Station (FSS) 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 availability of two-way voice communication
and HIWAS is indicated in the Chart Supplement
U.S. and aeronautical charts.

b. 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 Chart Supplement U.S.

1-1-13. User Reports Requested on
NAVAID or Global Navigation Satellite
System (GNSS) Performance or
a. Users of the National Airspace System (NAS)
can render valuable assistance in the early correction

of NAVAID malfunctions or GNSS problems and are

encouraged to report their observations of undesir-
able performance. Although NAVAIDs are
monitored by electronic detectors, adverse effects of
electronic interference, new obstructions, or changes
in terrain near the NAVAID can exist without


detection by the ground monitors. Some of the
characteristics of malfunction or deteriorating
performance which should be reported are: erratic
course or bearing indications; intermittent, or full,
flag alarm; garbled, missing or obviously improper
coded identification; poor quality communications
reception; or, in the case of frequency interference, an
audible hum or tone accompanying radio communic-
ations or NAVAID identification. GNSS problems are
often characterized by navigation degradation or
service loss indications.

b. Reporters should identify the NAVAID (for
example, VOR) malfunction or GNSS problem,

location of the aircraft (i.e., latitude, longitude or

bearing/distance from a NAVAID), magnetic head-
ing, altitude, date and time of the observation, type
of aircraft (make/model/call sign), and description of
the condition observed, and the type of receivers in
use (i.e., make/model/software revision). For GNSS

problems, if possible, please note the number of
satellites being tracked at the time of the anomaly.
Reports can be made in any of the following ways:
1. Immediately, by radio communication to the
controlling Air Route Traffic Control Center
(ARTCC), Control Tower, or FSS.

2. By telephone to the nearest FAA facility.
3. For GNSS problems, by internet via the GPS
Anomaly Reporting Form at http://www.faa.gov/

c. In aircraft that have more than one receiver,
there are many combinations of possible interference
between units. This can cause either erroneous
navigation indications or, complete or partial
blanking out of the communications. Pilots should be
familiar enough with the radio installation of the
particular airplanes they fly to recognize this type of

1-1-14. LORAN

In accordance with the 2010 DHS Appropriations Act, the
U.S. Coast Guard (USCG) terminated the transmission of

all U.S. LORAN-C signals on 08 Feb 2010. The USCG also
terminated the transmission of the Russian American
signals on 01 Aug 2010, and the Canadian LORAN-C
signals on 03 Aug 2010. For more information, visit
http://www.navcen.uscg.gov. Operators should also note

1-1-14 Navigation Aids

Page 68 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   67 -- Page 68 -- 69