NUSPM
NUSPM
The Global Maritime Distress and Safety System (GMDSS) connects ships with shore services and other vessels using several communication technologies. Its purpose is to improve the chance that a distress alert reaches people able to coordinate or provide assistance.
This overview explains the system. It does not teach equipment operation; only qualified training and the vessel’s approved procedures should do that.
A network, not one device
Depending on the vessel and sea area, the GMDSS arrangement may include terrestrial and satellite radio services, Digital Selective Calling (DSC), emergency position-indicating radio beacons (EPIRBs), search-and-rescue locating equipment and receivers for maritime safety information.
Each component has a defined purpose. Equipment carriage, maintenance and qualified operation depend on the vessel’s requirements.
Distress, urgency and safety
- Distress concerns grave and imminent danger requiring immediate assistance.
- Urgency concerns an urgent message about the safety of a ship, aircraft, person or vehicle without necessarily meeting the distress threshold.
- Safety communications include important navigational or meteorological warnings.
Use the terminology, priority and procedure taught in approved training. An incorrect transmission can delay response or create confusion.
EPIRBs in context
An EPIRB can transmit identifying and position-related information through a satellite-supported alerting chain. Registration details, installation, testing and maintenance are critical. Crew should know the vessel-specific location and assigned emergency duties, but should not improvise activation or testing from a web article.
Preventing and responding to false alerts
False alerts burden rescue services and may divert resources. Follow authorised test procedures, protect equipment from accidental activation and report a false alert immediately using the prescribed cancellation process. Never ignore an accidental activation in the hope that it will disappear.
Maritime safety information
GMDSS also distributes navigational warnings, meteorological warnings and forecasts, and other urgent safety information. Watchkeepers must understand which equipment and procedures deliver this information on their vessel and ensure it is considered in operations.
Familiarisation checklist
- Know who is qualified and responsible for radio duties.
- Locate relevant equipment and backup power arrangements.
- Understand where operating instructions and logs are kept.
- Know your muster-list communication role.
- Report defects or expired service items.
- Participate in authorised drills without transmitting a real alert.
Authoritative references
- IMO — Radiocommunications and Search and Rescue
- IMO — Circulars related to the GMDSS
- IMO — SOLAS Convention
After a distress alert, maritime search and rescue (SAR) is a coordinated process—not a single rescue vessel racing toward a point. Rescue authorities assess available information, identify suitable resources and organise a response across defined search-and-rescue regions.
From alert to coordination
A distress alert may reach a rescue coordination centre through radio, satellite-supported systems, a beacon, another vessel or another authority. Coordinators seek to confirm key facts and build a reliable operational picture.
Useful information can include:
- vessel identity and position;
- nature of distress and assistance required;
- number of people involved;
- injuries or immediate hazards;
- communications available;
- weather, sea state and vessel condition.
Accuracy matters. Give updates through trained channels and avoid speculation.
How help is organised
The rescue coordination centre may involve nearby merchant ships, rescue vessels, aircraft, coast stations and neighbouring authorities. Geography, conditions, capability and urgency shape the plan. A shipmaster receiving a distress message may have duties relating to assistance, subject to the applicable circumstances and safety of their own ship.
SAR regions allocate coordination responsibility; they are not political borders that prevent cooperation. Maritime rescue often depends on services working across boundaries.
What crew should do
Follow the master, alarm instructions, muster list and vessel emergency procedures. Prepare equipment or information only as directed. Maintain communications discipline and preserve the accuracy of passenger or crew counts.
Do not publish live operational details or casualty information on social media. Unverified messages can distress families, breach privacy and complicate response.
If your vessel is assisting
Your own master will assess the situation and direct preparations. Crew may be assigned lookout, communication, recovery, medical or accommodation duties. Use the vessel’s plans and trained methods. Do not improvise a recovery technique from an online summary.
After rescue
Recovery is not the end of the incident. Survivors may need urgent medical assessment, warmth, food, communication assistance and trauma-informed support. Identities and personal details should be protected. Crew involved in a difficult rescue may also benefit from debriefing and wellbeing support.