1The lesson in plain words
In one sentence…
An integrated drill connects decisions and records while you practise without radiating real distress.
What does it train?
An integrated exercise connects priority, medium, identity, position, time, follow-up, backup and records; it joins the decision chain without becoming an examination.
How do you start?
State the fictional vessel and identities, sea area and service, then use a non-radiating mode or approved test mode.
What do you change?
Change one condition at a time: the primary medium fails, the position is stale, someone needs medical help, or an accidental alert appears.
What does it not demonstrate?
A correct result does not prove current coverage, vessel compliance, SAR receipt or accreditation; it demonstrates bounded learning.
2Step by step
Integrated GMDSS drill
- 1
State the fictional vessel, voyage, medium and source version.
It fixes the scenario and keeps its assumptions visible.
- 2
Classify the situation: distress, urgency, safety or routine.
Priority determines the next decision.
- 3
Confirm the fictional identity and best available position and time.
It prevents ignoring a stale position without recognising it.
- 4
Choose the available simulated path without inventing coverage.
A1–A4 are not universal button routes.
- 5
Plan the voice or satellite follow-up and listening response.
Follow-up communication and listening are part of the exercise.
- 6
Check the backup equipment and write the fictional record.
The record makes learning traceable, not an official ship log.
- 7
Explain one fact, one equipment issue and one administration issue.
The debrief separates observations from dependencies and supports safe repetition.
3Key data
- A1–A4 areas
- Service and carriage contexts
- A3 context
- Depends on recognised satellite service
- Practice mode
- Isolated simulation or approved test
- Drill boundary
- Never radiate real distress
- Workflow order
- Facts, path, record, debrief
- IMO reference
- MSC.514(105)
- Classification
- Distress, urgency, safety or routine
- Follow-up
- Voice or satellite, with listening
4Key points
- 1.
State vessel, voyage, medium and source version.
- 2.
Priority → identity → position/time → path → follow-up → backup → record.
- 3.
Practise in isolated simulation or approved test mode.
- 4.
Debrief: observed fact, equipment and administration.
5Frequent mistakes
Wrong: "If it is a drill, I can transmit real distress."
Right: Practise with isolated simulation or approved mode; never transmit real distress.
Wrong: "A1–A4 are four fixed button routes."
Right: They are service and carriage contexts; the path depends on the scenario and available service.
Wrong: "A perfect worksheet proves coverage, compliance or GOC."
Right: It demonstrates bounded learning, not current coverage, compliance, accreditation or SAR outcome.
6Practice case & exam keys
Situation
In a simulator drill, a ship 280 NM offshore with MF/HF DSC and Inmarsat C has a crew member with severe chest pain, conscious but deteriorating. The Inmarsat C terminal shows NOT LOGGED IN and the DSC position is 40 minutes old at 12 knots.
What must you explain before advancing?
Show the answer →
The priority (urgency: a PAN-PAN medical call to reach TMAS through an HF coast station, escalating to distress only if the doctor confirms an immediate threat to life), the path (HF, since the satellite terminal is down), the position with its time and roughly 8 NM uncertainty, the backup check, and the log entry.
Why: A medical case is normally urgency: the first need is medical advice. If the doctor finds that a life now depends on immediate assistance, the priority can rise to distress. With the terminal down, HF is the remaining long-range path. 40 minutes at 12 knots is 8 NM, so the voice message must give the current position. Everything stays in test mode, and nothing implies certification or real coverage.
Exam keys
When you see «A1–A4» and «fixed route», reject it: they are contexts, not universal buttons.
When you see «practice mode», look for isolated simulation or approved test, never real transmission.
For a result, distinguish traceable learning from coverage, compliance or accreditation.
How to read it
Think of the drill as a chain: facts justify the priority, path, follow-up and record.
An honest debrief says what you observed, what depends on equipment and what depends on administration.
7Go deeper: GOC exam level
The detail behind each step for the General Operator's Certificate: the rules, the radio technique and worked cases.
Five integrated cases
Case 1 — Fire 450 NM offshore, 0215 UTC
A merchant ship 450 NM from the coast has an uncontrolled engine-room fire. 24 persons on board. No VHF coast coverage; MF/HF and the satellite terminal work; GNSS is fine.
Reasoned answer. Distress. There is no single universal sequence when several means are ready: the aim is ship-to-shore alerting by independent paths. Start an MF/HF DSC alert on a suitable band and/or a satellite distress alert according to the ship's procedures. On MF, 2187.5 kHz DSC / 2182 kHz voice only if coverage is expected; on HF choose the band by propagation, with 8414.5 kHz as a common start and 4/6/12/16 MHz as alternatives. Include identity, position and time, FIRE/EXPLOSION, and prepare the MAYDAY. The EPIRB becomes especially relevant if the ship has to be abandoned or other means fail; it is not activated by routine.
Case 2 — An HF distress alert from far away
You receive a DSC distress alert on 8414.5 kHz. No coast station is heard yet. The casualty is 600 NM away; another merchant ship is about 20 NM from it according to AIS.
Reasoned answer. No DSC acknowledgement from a ship station on HF. Watch for the coast acknowledgement and set the band's voice frequency, 8291 kHz. If no coast station acknowledges within about five minutes, inform a coast station or RCC by any means; send a DSC relay only if that station asks for one, and never to all ships. The nearby ship is useful information for the RCC, not a substitute for your own watch and coordination.
Case 3 — Accidental VHF alert during a test
During a test the operator presses DISTRESS by accident and the set confirms transmission.
Reasoned answer. Do not switch off and carry on. DSC self-cancel if available; go to Channel 16; transmit an ALL STATIONS cancellation with name, call sign, MMSI and the UTC time of the false alert; keep watch and answer the coast station or RCC. Record it and find the cause so it does not happen again.
Case 4 — Poor HF propagation at night
0200 UTC, a 1,700 NM circuit. 4 MHz is very noisy; 8 MHz has less noise and a moderate signal; 12 MHz gives nothing.
Reasoned answer. "Night = low frequency" does not force 4 MHz. If 8 MHz is below the circuit's MUF and gives a better SNR, it can outperform 4 MHz. Try bands with judgement, watch for acknowledgements and use redundancy.
Case 5 — A frozen GNSS position
The VHF DSC display has shown the same position for 5 hours while the ship makes 17 knots.
Reasoned answer. A future alert would carry a position about 85 NM out and delay SAR. Investigate the GNSS feed, enter position and time manually, and repair the connection. SOLAS sets 4 hours as the maximum interval for manual updates when the feed fails while underway; in practice act now.
Emergency procedures for the radio station itself
STCW A-IV/2 lists three emergencies every GOC must be ready for.
| Emergency | What the operator does |
|---|---|
| Abandon ship | Send or update the distress alert and MAYDAY if time allows; take the survival VHF sets and the SART or AIS-SART; if there is time, release the EPIRB by hand (even a float-free one), activate it and secure it to the raft; report the abandonment |
| Fire or damage at the radio station | Use the radio installation from another position if fitted, or the portable and survival-craft sets; send alerts early, before the fire forces you out |
| Partial or full failure of the radio installation | Switch to the other means (duplicated sets, satellite, portable VHF, EPIRB as last resort), use the reserve source, inform the company and coast station, record the failure and request repair |
Rapid-fire questions
| Question | Short answer |
|---|---|
| Why is A1 not "30 NM"? | It is defined by VHF coast-station coverage with continuous DSC alerting, not by distance |
| DSC or voice? | DSC is structured digital signalling to alert or set up a call; voice carries the traffic |
| Channel 70 or 16 to talk? | 16; Channel 70 is DSC only |
| 2187.5 or 2182 for a DSC alert? | 2187.5 kHz is DSC; 2182 kHz is voice |
| Voice partner of 8414.5 kHz? | 8291 kHz |
| Why several HF DSC frequencies? | To follow changing propagation and raise the chance of reception |
| Who normally acknowledges a DSC distress alert? | A coast station or RCC |
| What is EGC? | Enhanced Group Call: selective satellite broadcast of MSI and SAR information |
| NAVTEX B2 = D? | SAR, piracy, tsunami and natural-phenomena messages; it sounds the alarm |
| Radar SART = AIS-SART? | No: one answers X-band radar, the other transmits on AIS VHF |
| Reserve source endurance? | 1 h with a compliant emergency source feeding the radio; 6 h without |
| GNSS feed to DSC fails? | Update position and time manually, at most every 4 h while underway, and fix the fault |
| NBDP still a distress means? | No; it was removed from MF/HF distress and safety |
| What is ACS? | DSC-based automatic set-up of MF/HF links |
| Is Inmarsat the only RMSS? | No; Iridium is operational and other services have been recognized |
| VSWR 1:1 means a good antenna? | No; a match can still radiate poorly |
| Why does more power not always fix HF? | The problem may be propagation, skip zone, noise, antenna, ATU or receiver |
The frequencies you must know cold
| System | Frequency / channel | Function |
|---|---|---|
| VHF DSC | Ch 70 – 156.525 MHz | Distress, urgency, safety and calling by DSC |
| VHF voice | Ch 16 – 156.800 MHz | Distress, safety and calling; distress traffic |
| VHF bridge | Ch 13 – 156.650 MHz | Bridge-to-bridge navigational safety |
| VHF SAR | Ch 6 – 156.300 MHz | Intership, SAR and on-scene |
| MF DSC / voice | 2187.5 / 2182 kHz | Distress and safety |
| HF DSC | 4207.5 / 6312 / 8414.5 / 12577 / 16804.5 kHz | Distress and safety DSC |
| HF voice | 4125 / 6215 / 8291 / 12290 / 16420 kHz | Distress and safety voice |
| NAVTEX | 518 kHz (international), 490 and 4209.5 kHz (national) | MSI |
| EPIRB | 406.0–406.1 MHz | Cospas-Sarsat alert |
| AIS1 / AIS2 | 161.975 / 162.025 MHz | AIS, AIS-SART, EPIRB-AIS |
| Radar SART | 9.2–9.5 GHz | Locating on X-band radar |
References: ITU-R M.541 · SOLAS IV as amended by MSC.496(105)
GOC exam check
An uncontrolled engine-room fire breaks out 450 NM offshore. There is no VHF coast coverage; MF/HF, the satellite terminal and GNSS work. How do you alert?
8Full lesson & sources
Open the full lesson (diagrams and official references)
Practise distress in A1, A2 and the ship-specific A3/A4, loss of a primary medium, medical urgency/distress, false-alert cancellation, abandonment and receipt of route-relevant MSI. Use isolated simulation or the approved equipment test mode. Never deliberately transmit a real distress alert for practice.
Check priority, available communication path, identity and position/time, voice or satellite follow-up, listening and coordination, backup equipment and records. If a real false alert escapes a drill, stop the exercise and cancel it immediately. Debrief errors and repeat safely. These are study exercises, not universal official GOC pass marks, examination time limits or accreditation; the examining administration sets its own approved assessment.
Make the drill a controlled decision
An integrated drill puts everything from the previous lessons into one evolving incident. You are scored on the reasoning, not on how fast you press buttons. Run it in a non-radiating simulator or approved equipment test mode, with a fictional ship and fictional identities, and state the assumptions at the start: sea area, equipment fitted, satellite service carried.
One scenario, several checks
Here is a worked scenario. The bulk carrier NORDIC ALBA, 24 crew, is 280 NM west of the nearest coast at 0130 UTC. She carries VHF DSC, MF/HF DSC, Inmarsat C and a float-free EPIRB, and is in A3 for her Inmarsat service. The instructor adds one new fact at a time:
| Inject | Decision | Reasoning |
|---|---|---|
| 0130: No. 1 hold flooding, pumps keeping up | PAN-PAN to the RCC via Inmarsat C or MF/HF; report position and situation | Serious, but not yet grave and imminent |
| 0215: pumps failing, list 12° and increasing | Upgrade to distress: satellite alert plus HF DSC alert, then MAYDAY by voice as soon as possible | Two independent services; the danger is now imminent |
| 0220: HF alert acknowledged by a coast station on 8414.5 kHz | Distress traffic on 8291 kHz with that station | The acknowledgement tells you which band works |
| 0240: GNSS fails | Give the last position with its time, plus course and speed since; update the DSC position by hand | 20 minutes at 4 knots is about 1.3 NM of uncertainty |
| 0300: master orders abandon ship | Final position by voice; take the survival VHF and SART; the EPIRB is activated and taken to the raft | Alert, locate, communicate |
Sea areas are service and carriage contexts, not four button routes. NORDIC ALBA had two independent long-range paths because she was equipped for A3. A ship in the same position with only Inmarsat C would have had one, and her drill would have to show what she does if it fails.
Branches the instructor can add
Change one condition at a time and ask what changes.
- 1Another ship's HF distress alert arrives at 0200. That is a separate branch: listen on the voice frequency, inform the shore, and relay only if asked, while handling your own flooding.
- 2The satellite terminal shows NOT LOGGED IN. HF becomes the only long-range path: check the terminal, log the fault, and do not assume the shore heard the earlier PAN-PAN through it.
- 3Someone presses DISTRESS on the VHF by accident during the drill. Hard stop: cancel and log it.
- 4A NAVTEX gale warning arrives. Plot it, and decide whether it affects when you abandon and where the rafts will drift.
False alerts and the assessment boundary
IMO guidance in MSC.514(105) on avoiding false distress alerts is the safety boundary for every drill. Most false alerts happen during tests, maintenance and training. Keep distress buttons covered, announce the drill on board, and keep the cancellation card next to the console.
This site can check whether you classified the situation, kept identity and position with time, chose a path consistent with the stated equipment, and logged your reasoning. It cannot give you a GOC pass, an exam time or a certificate. Those come from the Administration's approved examination.
Sources: IMO MSC.514(105) index; IMO GMDSS circulars; IMO SAR documents and current DSC procedure listing.
Official references · 2026-09-09
9Test your knowledge
What should the exercise use to avoid radiating real distress?
Keep studying…
Reviewed by Ramon Curto, Nautical teacher at IECNPC · Last reviewed: