A navigational warning is a broadcast message alerting vessels to hazards affecting safe navigation in a given area — covering dangers not necessarily shown on charts or that have emerged since the chart’s last update.
What Navigational Warnings Cover
- Wrecks and obstructions — recently discovered or newly hazardous
- Military exercises — areas where naval activity may pose a hazard or restrict passage
- Malfunctioning aids to navigation — lighthouses, buoys, or other navigation marks not functioning correctly
- Ice hazards — in relevant regions and seasons
- Other dangers — anything from drifting containers to unusual weather hazards affecting a specific area
How Warnings Are Distributed
- NAVTEX — automated text broadcast system covering coastal waters, received and printed automatically by onboard NAVTEX receivers
- SafetyNET (INMARSAT) — satellite-based broadcast covering ocean areas beyond NAVTEX’s coastal range
- VHF — local, shorter-range voice broadcasts, often used by port authorities or coast guards for immediate local hazards
Why This Matters for Passage Planning
Charts are updated periodically but can’t reflect every hazard in real time — navigational warnings are the mechanism that fills this gap, and reviewing current warnings for the intended route is a standard, mandatory part of passage planning, not an optional extra step.
Exam Relevance
Navigational warning systems (NAVTEX, SafetyNET) and their role in passage planning are core GMDSS and Navigation topics in deck officer competency exams.