WPC GMDSS ROC (India) cheat sheet

GMDSS combines satellite (Inmarsat) and terrestrial (DSC, NAVTEX, VHF/MF/HF radiotelephony) subsystems to ensure distress alerting, SAR coordination, MSI, and general communications.

Functional requirements: distress alerting, SAR coordination, on-scene communications, locating signals, MSI, and general radiocommunications (bridge-to-bridge included).

Sea areas: A1 (VHF coast station coverage), A2 (MF coast station coverage), A3 (Inmarsat coverage, excluding A1/A2), A4 (outside A1–A3, polar regions).

Every ship must carry VHF DSC (Ch 70), at least one SART, and two-way VHF radiotelephone apparatuses for survival craft.

Distress alert routes: VHF Ch 70 DSC to coast stations (A1); MF 2187.5 kHz DSC (A2); Inmarsat or HF DSC (A3/A4).

NAVTEX receiver required for MSI in A1/A2; SafetyNET (Inmarsat) or HF NBDP for A3/A4 as appropriate.

GMDSS equipment must be powered from the main and emergency sources; reserve power (battery) capacity specified for 1 h (with emergency generator) or 6 h (without).

Distress alerts via DSC include ship's MMSI, position, nature of distress, and time; they are addressed to 'All Ships' or a specific coast station.

Sea area A1: coverage by VHF coast stations with continuous DSC alerting (approx. 20–30 nm).

Sea area A2: coverage by MF coast stations with continuous DSC alerting on 2187.5 kHz (approx. 100–150 nm).

Sea area A3: within Inmarsat geostationary satellite coverage (approx. 70°N–70°S), excluding A1 and A2.

Sea area A4: outside A1, A2, and A3; polar regions; requires HF DSC and HF radiotelephony/NBDP.

Ships in A1 must carry VHF DSC, SART, two-way VHF, and NAVTEX (if available).

Ships in A2 additionally carry MF DSC (2187.5 kHz) and MF radiotelephony (2182 kHz).

Ships in A3 additionally carry Inmarsat ship earth station (or HF DSC as alternative) and MSI reception via SafetyNET or HF NBDP.

Ships in A4 carry HF DSC and HF radiotelephony/NBDP for distress and MSI; Inmarsat not available.

Carriage requirements are specified in SOLAS Chapter IV and Indian Merchant Shipping (GMDSS) Rules; surveys verify compliance.

Priority order: Distress (Mayday) > Urgency (Pan Pan) > Safety (Securite) > Routine.

Distress signal: MAYDAY (spoken) or SOS (Morse); urgency: PAN PAN; safety: SECURITE.

Distress call format: MAYDAY ×3, this is [ship name/callsign] ×3, MAYDAY [ship name/callsign], position, nature of distress, assistance required, persons on board, other information.

Distress acknowledgement by coast station: MAYDAY [ship's name/callsign], received MAYDAY, then control of distress traffic.

Urgency call: PAN PAN ×3, All Stations ×3 (or addressed station), this is [ship name/callsign], position, nature of urgency, assistance required.

Safety call: SECURITE ×3, All Stations ×3, this is [ship name/callsign], safety message follows.

Silence periods: 00–03 and 30–33 minutes past each hour on 500 kHz (historical) and 2182 kHz; GMDSS uses DSC 2187.5 kHz for alerting.

Distress traffic must be terminated by the station controlling it with MAYDAY [ship name], silence finished (or SEELONCE FEENEE).

DSC uses VHF Ch 70 (156.525 MHz), MF 2187.5 kHz, and HF 4207.5, 6312, 8414.5, 12577, 16804.5 kHz for distress alerts.

MMSI: 9 digits; ship stations: MID (3 digits) + 6 digits; coast stations: 00 + MID + 4 digits; group: 0 + MID + 5 digits.

Distress alert via DSC: press DISTRESS button (cover lifted), select nature of distress, hold for 5 seconds until alarm sounds; transmitted on default distress frequency.

DSC distress alert contains: format specifier (distress), MMSI, nature of distress, position (if interfaced), time, and telecommand (radiotelephony).

After sending distress alert, wait 15–30 seconds for acknowledgement; if none, retransmit or try another frequency/equipment.

DSC watchkeeping: continuous watch on VHF Ch 70, MF 2187.5 kHz, and HF distress frequencies (as per sea area).

DSC routine call: select station MMSI, choose working channel, send; receiving station acknowledges on DSC then switches to working channel.

False DSC distress alert: immediately cancel via DSC (if possible) or radiotelephony on distress frequency; notify coast station; log incident.

VHF Ch 16 (156.800 MHz) is the international distress, safety, and calling channel; Ch 70 is DSC only (no voice).

VHF Ch 13 (156.650 MHz) is bridge-to-bridge navigation safety; Ch 06 is inter-ship; Ch 09 is alternate calling.

MF distress and calling frequency: 2182 kHz (radiotelephony); DSC: 2187.5 kHz.

HF distress and calling frequencies (radiotelephony): 4125, 6215, 8291, 12290, 16420 kHz; corresponding DSC: 4207.5, 6312, 8414.5, 12577, 16804.5 kHz.

VHF range is approximately line-of-sight; typical ship-to-ship 10–20 nm, ship-to-coast up to 30–40 nm depending on antenna height.

MF range (2182 kHz) groundwave: up to 100–150 nm by day; HF range varies with ionospheric propagation and frequency selection.

Radiotelephony distress procedure: MAYDAY ×3, this is [ship name] ×3, MAYDAY [ship name], position, nature of distress, assistance required, persons on board, over.

When transmitting on 2182 kHz, use low power (≤ 400 W) and keep transmissions brief to allow distress watch.

Inmarsat provides global coverage except polar regions (approx. 70°N–70°S) via geostationary satellites.

Inmarsat-C: store-and-forward messaging, distress alerting, SafetyNET reception; compact terminal; used in A3.

Inmarsat Fleet (F77/FB): voice and data; Inmarsat Mini-C for small craft.

Distress alert via Inmarsat-C: select Distress, enter nature, position, press Send; alert routed to RCC via LES.

SafetyNET: Inmarsat broadcast service for MSI (navigational and meteorological warnings, SAR information) to specific sea areas.

Inmarsat-C terminal must have updated position input (GPS) for effective distress alerting; manual position entry if interfaced fails.

Enhanced Group Call (EGC) is the SafetyNET system; receivers can be programmed to receive MSI for a given sea area (e.g., NAVAREA).

Inmarsat-C can also be used for two-way distress communications with RCC after alert.

406 MHz EPIRB: transmits distress alert to COSPAS-SARSAT satellites; includes MMSI, position (if GPS), and homing signal on 121.5 MHz.

EPIRB activation: manually (switch) or automatically (hydrostatic release) when submerged; float-free mounting required.

EPIRB registration: must be registered with national authority (India: DG Shipping); update details on change of ship/owner.

SART (Search and Rescue Transponder): radar transponder operating in 9 GHz band; responds to radar with a series of dots on radar screen.

SART range: approximately 5–10 nm depending on radar height; battery capacity ≥ 96 hours standby, ≥ 8 hours active.

AIS-SART: transmits AIS message 1 (position) and message 14 (safety) on AIS frequencies; displayed on AIS and some radar/ECDIS.

SART mounting: in survival craft or on bridge with quick access; test using radar or built-in test facility.

EPIRB battery replacement: typically every 5 years (or as per manufacturer); expiry date marked on beacon.

NAVTEX: international automatic direct-printing system on 518 kHz (English), 490 kHz (national), 4209.5 kHz (tropical).

NAVTEX message categories: A (navigational warnings), B (meteorological), C (ice), D (SAR), E (weather forecast), F (pilot), etc.

NAVTEX receiver should be programmed with correct station and message type selection; typically receives all relevant categories.

NAVTEX coverage: approximately 200–400 nm from coast station; required in Sea Areas A1 and A2.

SafetyNET (Inmarsat EGC) provides MSI to A3 and A4; receiver programmed for NAVAREA/METAREA.

MSI includes navigational warnings, meteorological warnings, SAR information, and other urgent safety information.

NAVTEX and SafetyNET messages are broadcast on scheduled times; urgent messages (SAR, distress) are broadcast immediately.

In India, NAVTEX service is provided by coast stations (e.g., Mumbai, Chennai, Kolkata) under NAVAREA VIII coordinator.

Ship radio station licence issued by national administration (India: Ministry of Communications, WPC wing); must be on board and valid.

Operator certificates: GMDSS General Operator's Certificate (GOC) or Restricted Operator's Certificate (ROC); ROC limited to A1/A2? Actually ROC is for A1 only; GOC for all areas.

ROC (Restricted Operator's Certificate) is valid for Sea Area A1 only; GOC for all sea areas.

Watchkeeping: continuous DSC watch on VHF Ch 70, MF 2187.5 kHz, and HF distress frequencies as required; radio watch maintained by qualified operator.

Radio log: must record all distress, urgency, safety communications, watch periods, equipment failures, and position reports.

Silence periods: 00–03 and 30–33 minutes past each hour on 2182 kHz (and historically 500 kHz); avoid transmissions except distress during these periods.

Licence renewal and equipment approval: GMDSS equipment must be type-approved; surveys verify compliance.

False alert penalties: transmitting false distress alerts is an offence under national law and ITU Radio Regulations.

GMDSS reserve power: battery capacity to supply distress and safety equipment for 1 hour (with emergency generator) or 6 hours (without).

Battery types: lead-acid (vented or VRLA) or NiCd; must be tested at intervals (specific gravity, voltage, capacity test).

Battery maintenance: keep terminals clean and tight, check electrolyte level (vented), ensure ventilation, record test results.

Emergency generator: must start automatically within 30 seconds and supply power for at least 3 hours (SOLAS).

Antenna types: VHF whip (vertical), MF/HF wire or whip, Inmarsat stabilized antenna; keep clear of obstructions and insulators dry.

Common faults: corroded connections, water ingress in coax, blown fuses, faulty PTT switch, incorrect antenna tuning.

Standing wave ratio (SWR) check: high SWR indicates antenna/feeder fault; use built-in meter or external SWR meter.

Battery charging: verify charging voltage and current; equalizing charge for lead-acid as per manufacturer.

Radio log entries: date/time, frequencies used, stations contacted, distress/urgency/safety traffic, watch periods, equipment status, false alerts.

False alert procedure: immediately inform coast station via DSC or radiotelephony; cancel alert if possible; log details and notify authorities.

False alert via EPIRB: switch off, notify RCC (e.g., via Inmarsat or VHF), follow up with written report.

Records retention: radio log and certificates must be available for inspection by surveyors and authorities.

Operational safety: avoid testing distress functions on air; use built-in test or dummy load; never transmit without antenna connected.

Distress alert cancellation: transmit MAYDAY [ship name], this is [ship name/callsign], cancel distress alert, over; then acknowledge.

Reporting requirements: accidents, equipment failures, and false alerts must be reported to flag state and coast station.

Safety practices: maintain watch, keep equipment charged, conduct regular drills (fire, abandon ship, radio distress).

ITU Radio Regulations govern frequency allocations, distress frequencies, and operator qualifications; national regulations supplement.

Ship station licence: issued by WPC (India) for the ship; operator certificate (GOC/ROC) issued by DG Shipping approved training institutes.

GMDSS operator certificate validity: GOC/ROC valid for 5 years; revalidation requires sea service or refresher course.

Watchkeeping obligations: continuous watch on VHF Ch 70, MF 2187.5 kHz, HF DSC frequencies, and Inmarsat (as applicable) while at sea.

Radio watch may be maintained by qualified operator or automated equipment (DSC, NAVTEX, EGC) with alarm to bridge.

Frequencies: 2182 kHz (MF distress), 4125/6215/8291/12290/16420 kHz (HF distress), 156.8 MHz (VHF Ch 16).

Licence documents: ship station licence, operator certificate, safety certificates, radio log; must be available for inspection.

Penalties: operating without licence, causing harmful interference, or false distress alerts can lead to fines or imprisonment.