Navigational Warnings

• Navigational Warnings


  Messages disseminated to seafarers to alert them to potential hazards or dangers in navigable waters
• Navigational Warnings


  • Crucial for promoting maritime safety
  • Ensure vessels can navigate with awareness of obstacles, hazards, or other navigational concerns
• Information included in Navigational Warnings


  • Navigational Hazards
  • Weather Conditions
  • Maritime Events
  • Security Concerns
• Categories of Radio Navigational Warnings

  • NAVAREA Warnings
  • METAREA Warnings
  • Coastal Warnings
  • Local Navigational Warnings
  • Ice Navigational Warnings
  • Tropical Cyclone Warnings
  • Broadcast Notices to Mariners (NMs)
• NAVAREA Warnings


  Provide information on hazards to navigation that may affect multiple maritime zones within a particular area
• METAREA Warnings


  Provide meteorological and oceanographic information relevant to navigation, including weather forecasts, storm warnings, and sea state conditions
• Coastal Warnings


  Issued for specific coastal areas and include information on hazards such as wrecks, obstructions, changes in navigational aids, and other local conditions that may affect safe navigation near the coastline
• Types of Coastal Warnings

  • Gale Warning
  • Coastal Flood Warning
• Gale Warning


  Inform communities and coastal areas about strong winds, big waves, and other associated hazards
• Coastal Flood Warning


  Indicate that coastal flooding is either imminent or already occurring along coastlines bordering the Atlantic Ocean, Pacific Ocean, or the Gulf of Mexico
• Local Navigational Warnings


  Issued for specific waterways, ports, or harbors and provide detailed information on local hazards, navigational restrictions, temporary obstructions, and other relevant conditions
• Examples of Local Warnings


  • Rainfall and Thunderstorm Warning
  • Seismic Hazard Assessment
  • Tsunami Warnings
  • Storm Surge Information
  • Flood Forecasting and Warning System
• WWNWS (World-wide Navigation Warning Service) guidance and coordination are involved with only NAVAREA and Coastal Warnings and, of the latter, only with those Coastal Warnings which are broadcast under the internationally coordinated services using NAVTEX, or in lieu of NAVTEX, the International Safety NET service, as their principal means of transmission
• Ice Navigational Warnings


  Provide information on the presence, extent, and movement of icebergs, ice floes, and other ice-related hazards
• Tropical Cyclone Warnings


  Provide information on the development, movement, and intensity of tropical cyclones (hurricanes, typhoons) that pose a threat to maritime navigation
• Broadcast Notices to Mariners (NMs)


  Provide important updates to navigational charts and publications, informing mariners about changes in navigational aids, harbor regulations, and other relevant information
• Methods of Transmitting Navigational Warnings


  • Navtex (Navigational Telex)
  • Radio Broadcasts
  • Electronic Chart Display and Information Systems (ECDIS)
  • Online Platforms and Websites
  • Notice to Mariners
• Navigational warnings


  Information transmitted to seafarers to ensure widespread dissemination and timely awareness
• Methods of transmission for navigational warnings


  1. Navtex (Navigational Telex)

  2. Radio Broadcasts

  3. Electronic Chart Display and Information Systems (ECDIS)

  4. Online Platforms and Websites

  5. Notice to Mariners
• Navtex (Navigational Telex)


  • International automated system for broadcasting maritime safety information, including navigational warnings, to ships
  • Navtex messages are transmitted on designated frequencies and are automatically received by Navtex-equipped vessels within range
• Radio Broadcasts


  • Maritime safety information, including navigational warnings, may be broadcasted via maritime radio services such as the Global Maritime Distress and Safety System (GMDSS)
  • These broadcasts are typically made on designated VHF, HF, or MF
• Electronic Chart Display and Information Systems (ECDIS)


  • Navigational warnings can be integrated into electronic navigational charts (ENCs) and displayed on ECDIS systems aboard vessels
  • These warnings are often received via electronic means, such as satellite or internet connections
• Online Platforms and Websites


  • Maritime authorities and organizations responsible for issuing navigational warnings often maintain websites or online platforms where seafarers can access updated information, including navigational warnings, Notices to Mariners, and other relevant notices
• Notice to Mariners


  • Navigational warnings may also be disseminated through official Notices to Mariners publications, which provide updates and corrections to nautical charts and publications used for navigation
• Inmarsat-C


  A two-way, packet data service operated by the telecommunications company Inmarsat which operates between mobile earth stations (MES) and land earth stations (LES)
• Inmarsat-C became fully operational after a period of pre-operational trials


  January 1991
• Inmarsat-C


  • Low cost
  • Smaller
  • Uses a smaller omni-directional antenna
• Disadvantage of Inmarsat-C


  Voice communication is not possible
• Inmarsat-C is approved for use under the Global Maritime Distress and Safety System (GMDSS)
• Inmarsat-C meets the requirements for Ship Security Alert Systems (SSAS) defined by the International Maritime Organization (IMO)
• Inmarsat-C is the most widely used service in fishing Vessel Monitoring Systems (VMS)