Issued by Hydrographic Offices, are notices that are usually more urgent than notices to mariners. They are normally concerned with changes of a temporary nature such as alterations to charts and hydrographic publications as well as changes, or failures, to navigational aids and any other matter that affects the safety of navigation. Such warnings are in text form and promulgated by coastal radio stations and on the NAVTEX system. They are also sent directly to satellite communication centres for international delivery and are coordinated in the sixteen NAVAREAS as part of the World-Wide Navigational Warning Service (WWNWS). This was established jointly by the International Maritime Organization and the International Hydrographic Organization in 1977 to promulgate by radio important information affecting the safety of navigation of ocean-going and coastal shipping.
Subjects: Maritime History.