JP 3-50 National Search and Rescue Manual Vol I - US Navy

links, commonly called phone patches, provide important links
through the commercial telephone system and marine operator to
craft at sea and by aeronautical radio stations to en route
aircraft.
6. The International Maritime Satellite Organization (INMARSAT),
telephone direct-voice communication, via geostationary
satellites, which is available to INMARSAT-equipped vessels.
B. Printed Communications that may be used are:
1. Teletypewriter Private Lines (TWPL), installed when the volume
of traffic justifies a private line dedicated to printed
communications. In some areas, particularly the continental
United States, special SAR dedicated circuits have been
established to carry operational SAR traffic.
2. Automatic Digital Network (AUTODIN), a widespread teletype
network using automatic switching circuits, used extensively
for military communications and by other government agencies
for operational and administrative printed communications.
3. Aeronautical Fixed Telecommunications Network (AFTN), an
international teletype network based on ICAO requirements for
air navigation services, including SAR. FAA Flight service
stations (FSSs) are the normal points of interface for United
states RCCs. Diagrams of implemented and planned circuits are
contained in the communications sections of the ICAO Regional
Air Navigation Plans. AFTN may be helpful when language is a
barrier. AFTN should not be routinely used for maritime SAR
when reliable alternative systems exist. However, ICAO has
agreed that it can be used by maritime RCCs. It has the
advantages of being global and of allowing message priorities
to be established, and is often the best alternative when
communicating with developing nations.
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