Chapter 28: Maritime Safety Systems
GMDSS, AIS and shore reporting systems form the distress, safety and traffic-awareness layer of modern navigation. The equipment carried depends on the sea area of operation.
GMDSS sea areas and equipment
Sea area A1 is within VHF coverage of a coast station with DSC (roughly 20–30 NM); A2 within MF DSC coverage (about 100–150 NM); A3 within Inmarsat geostationary coverage, approximately 76°N to 76°S; A4 is everything else — the polar regions — requiring HF. Equipment includes VHF/MF/HF DSC radios, a satellite EPIRB on 406 MHz, SARTs or AIS-SART, NAVTEX and an EGC/SafetyNET receiver, and two-way VHF portables for survival craft.
- A1 VHF DSC · A2 MF DSC · A3 Inmarsat · A4 HF (polar)
- 406 MHz EPIRB — registered, float-free, with GNSS position
- SART responds to 9 GHz radar; AIS-SART reports position to AIS displays
AIS, NAVTEX and reporting systems
AIS Class A is mandatory for SOLAS vessels and transmits static, dynamic and voyage data with a fast dynamic report rate; Class B is for smaller craft with lower power and slower reporting. AIS is an aid to situational awareness and must not be used alone for collision avoidance — data may be wrong, absent or manually mis-entered. NAVTEX delivers navigational warnings, weather and SAR information automatically on 518 kHz. AMVER is a voluntary worldwide ship reporting system that maintains a search-and-rescue plot of participating vessels; participation costs nothing and materially improves SAR response.
Key takeaways
- • The sea area (A1–A4) determines the required radio fit.
- • AIS supplements but never replaces radar and visual look-out for collision avoidance.
- • AMVER is voluntary; EPIRB registration is essential for the beacon to be useful.
Knowledge check
Immediate feedback with rationales. Answer each question to see the explanation.
Chapter 28 quiz
0 of 3 answered
1.GMDSS Sea Area A4 is:
2.A radar SART, when interrogated, produces on the radar display:
3.Relying on AIS alone for collision avoidance is unsafe because: