GMDSS Sea Area A1
For small craft SRC revision, VHF/DSC is commonly associated with GMDSS Sea Area A1, where VHF coast station coverage is expected.
- A1 is VHF DSC coverage
- VHF is not global
Marine Radio revision module 9 of 10
GMDSS
GMDSS & Safety Equipment
How VHF fits alongside EPIRB, PLB, SART, AIS, Navtex, and other distress or safety information systems.
GMDSS sea areas A1 and A2 awarenessSAR and rescue coordination centres
10 guided lessons · 20 practice questions · 20 flashcards
3 outcomes · self-guided revision
- Explain how VHF fits alongside EPIRB, PLB, SART, AIS, Navtex, and other distress or safety information systems.
- Apply GMDSS sea areas A1 and A2 awareness to a realistic onboard situation.
- Recall the core check: a1 is VHF DSC coverage.
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Lesson summaries
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EPIRB, PLB, and SART
An EPIRB alerts search and rescue through satellite systems. A PLB is a personal locator beacon. A SART helps rescuers home in at close range.
- EPIRB: vessel beacon
- PLB: personal beacon
AIS and Navtex
AIS exchanges vessel identity and movement data. Navtex receives maritime safety information such as navigational and weather warnings.
- AIS: vessel data
- Navtex: safety information
Where VHF Fits In GMDSS
For small craft, VHF DSC sits mainly in Sea Area A1 thinking: communication within range of VHF coast stations. It is powerful, but it is not global and it depends on aerial, power, range...
- VHF DSC is line-of-sight and range-limited.
- EPIRB/PLB satellite alerts need registration.
EPIRB, PLB, And Registration
An EPIRB or PLB can send a distress alert through satellite systems, but registration is what connects that alert to useful vessel and contact information.
- Register beacons and keep details current.
- Check battery and service dates.
SART, AIS, And Locating
Search and Rescue Transponders and AIS locating devices help rescuers find a survival craft or casualty after the alert has been raised. They are locating aids, not full two-way distress...
- SART/AIS SART help with final location.
- AIS is useful but incomplete.
Safety Information And Redundancy
Weather, navigation warnings, and maritime safety information may arrive through VHF broadcasts, Navtex, apps, harbour notices, or other sources. The skipper's task is to choose reliable...
- Know which safety information source applies to the area.
- Keep handhelds charged and protected.
GMDSS, Sea Areas, SAR, And MSI
GMDSS combines alerting, communication, locating, and Maritime Safety Information. Sea Area A1 is within VHF coast-station radiotelephone coverage where continuous DSC alerting is availab...
- A1 is defined by VHF coast-station DSC coverage, not a fixed distance from shore.
- A2 uses MF coast-station DSC coverage.
Read A NAVTEX Identity Before Reading The Message
A NAVTEX message identity uses B1 for the transmitter, B2 for the subject or message type, and B3B4 for the two-digit message number. Select transmitters for both the area you are in and...
Read the full lesson: Read A NAVTEX Identity Before Reading The MessageEPIRB, SART, And Survival-Craft VHF Checks
A 406 MHz EPIRB sends a coded distress alert through Cospas-Sarsat; many units also provide a 121.5 MHz homing signal. Keep registration and coding correct, the float-free mounting unobst...
- 406 MHz alerts satellites; 121.5 MHz supports local homing where fitted.
- Float-free EPIRB mounting must not be obstructed.
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