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Messages originated by the U.S. government which promulgate official warning of dangers to navigation, generally involving political situations. They remain active until canceled, and are published in Notice to Mariners No. 1 issued by DMAHTC.

Related Terms

MICROWAVE EARLY WARNING

High-power, long-range radar with a number of indicators, giving high resolution, and with a large traffichandling capacity; used for early warning of missiles.

HYDROLANT

A radio message disseminated by the National Imagery and Mapping Agency and restricted to important marine incidents or navigational changes which affect navigational safety. The HYDROLANT broadcast covers those water areas outside and eastward of NAVAREA IV in the Atlantic Ocean. HYDROLANTS constitute part of the U.S. long range radio navigational warning system. The text of HYDROLANTS issued during a week which are in effect are available through NAVINFONET and are printed in the weekly Notice to Mariners.

HYDROPAC

A radio message disseminated by the National Imagery and mapping Agency and restricted to important marine incidents or navigational changes which affect navigational safety. The HYDROPAC broadcast covers those water areas outside of NAVAREA XII in the Pacific Ocean. HYDROPACS constitute part of the U.S. long range radio navigational warning system. The text of HYDROPACS issued during a week which is in effect are available through NAVINFONET and are printed in the weekly Notice to Mariners.

NAVAREA

One of 16 areas into which the world's oceans have been divided for the dissemination of long-range navigational and meteorological warnings under the WWNWS

WWNWS

World-Wide Navigational Warning Service established by IMO in collaboration with I HO for the dissemination of navigational warnings to ships

MSI

Maritime Safety Information: navigational and meteorological warnings, forecasts and other urgent safety related messages broadcast to ships

OPERATING AREA CHART

A base chart with overprints of various operating areas necessary to control fleet exercise activities. Submarine Transit Lanes, Surface and Sub-surface Operating Areas, Air Space Warning Areas, Controlled Air Spaces, and other restricted areas are portrayed.

PINNACLE

A high tower or spire-shaped pillar of rock or coral on the sea floor, alone or cresting a summit. It may or may not be a hazard to surface navigation. Due to the steep rise from the sea floor no warning is given by sounding.

WARNING RADIOBEACON

An auxiliary radiobeacon located at a lightship to warn vessels of their proximity to the lightship. It is of short range and sounds a warbling note for 1 minute immediately following the main radiobeacon on the same frequency. Also called WARNING BEACON.

NAVTEX

Telegraphy system for broadcasting marine weather forecasts, navigational warnings, SAR alerts and other warnings and urgent information to ships in coastal waters (up to 400 nautical miles) under the WWNWS

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