FCC Restricted GMDSS (RG) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

GMDSS purpose

A SOLAS-based system combining satellite and terrestrial communications to alert shore SAR authorities automatically, coordinate rescue, broadcast MSI, and provide locating signals.

Sea Area A1

The sea area within VHF coverage of at least one coast station providing continuous DSC alerting, typically about 20 to 30 nautical miles offshore.

Sea Area A2

The sea area beyond A1 but within MF coverage of coast stations providing continuous DSC alerting, roughly 100 to 150 nautical miles from the coast.

Sea Area A3

The sea area beyond A1 and A2 within coverage of a recognized mobile-satellite service supporting alerting, roughly between 70 degrees north and 70 degrees south.

Sea Area A4

The remaining sea areas outside Inmarsat coverage, mainly polar regions, requiring HF DSC and narrow-band direct-printing radiotelegraphy on the 4, 6, 8, 12 and 16 MHz bands.

A1 carriage requirements

A vessel operating only in Sea Area A1 must carry VHF with DSC, a 406 MHz EPIRB or equivalent satellite alerting, an MSI receiver such as NAVTEX, and a SART.

VHF Channel 16

156.800 MHz, the international distress, safety and calling channel. It is monitored for distress, urgency and safety, and routine traffic moves to a working channel after contact.

VHF Channel 70

156.525 MHz, reserved exclusively for Digital Selective Calling. Voice transmission on this channel is prohibited because it would interfere with digital distress alerting.

VHF DSC distress alert

Lift the protective cover and hold the DISTRESS button for about five seconds. The alert goes on Channel 70 with the vessel MMSI and, if connected, position.

MAYDAY call format

Say MAYDAY three times, then the vessel name and call sign three times, followed by MAYDAY, name, position, nature of distress, assistance required and persons aboard.

PAN PAN meaning

The urgency signal, spoken three times, used for urgent messages about the safety of a vessel or person that do not yet involve immediate distress.

SECURITE meaning

The safety signal, spoken three times, used to announce important navigational or meteorological warnings that affect the safety of navigation.

Cancelling false DSC alert

Transmit a DSC distress cancellation on Channel 70 to all stations, then announce the false alert by radiotelephony on Channel 16, log the event and inform the coast station.

MAYDAY RELAY

A distress message transmitted on behalf of another station that cannot transmit itself. It is prefixed MAYDAY RELAY three times and includes the original station's details.

On-scene coordinator role

Usually the first vessel on scene or a SAR unit, designated by the rescue coordination centre to coordinate search patterns, communications and rescue operations.

Alerting versus coordination

The DSC alert on Channel 70 or an EPIRB alerts SAR authorities; the radiotelephony distress traffic on Channel 16 then supplies details and coordinates the response.

NAVTEX frequencies

518 kHz for international English broadcasts, 490 kHz for national broadcasts in local languages, and 4209.5 kHz in some regions, with coverage typically 200 to 400 nautical miles.

NAVTEX category A

Navigational warnings. Other common categories include B for meteorological warnings, D for search and rescue information, E for forecasts and Z for no message.

NAVTEX message header

Each message starts with a station identifier letter, a message type letter and a two-digit sequential number, allowing the receiver to accept or reject stations and types.

SafetyNET MSI

The Inmarsat Enhanced Group Call service that broadcasts maritime safety information in Sea Areas A3 and A4, and in A2 where NAVTEX coverage is unavailable.

406 MHz EPIRB

A float-free beacon that sends a digital distress alert with vessel identity and, if interfaced, position to the COSPAS-SARSAT system, plus a 121.5 MHz homing signal.

EPIRB registration

The beacon must be registered with the flag administration with vessel details and emergency contacts, and the registration updated when the vessel or ownership changes.

EPIRB battery and HRU

The battery typically needs replacement every five years as marked on the label, and the hydrostatic release unit must be renewed before its expiry date.

SART operation

A 9 GHz radar transponder that, when interrogated by a radar, shows a series of dots on the display. Switch it on when abandoning ship and mount it at least one metre above sea level.

Survival craft VHF

A waterproof, battery-powered portable radiotelephone carried in survival craft, operating on Channel 16 and a working channel, often with 121.5 MHz for homing.

121.5 MHz use

The aeronautical emergency frequency used for homing by SAR aircraft. A survival craft radio may transmit on it to attract attention, but it is not a working channel.

Survival craft radio battery

Must have capacity for the required operating period, typically eight hours or as specified. Keep the radio dry and warm and keep transmissions brief to conserve power.

Ship radio licence

Issued by the flag administration, it specifies the permitted equipment, frequencies and operating conditions, and must be kept on board for inspection.

Restricted Operator Certificate

The certificate authorizing operation of GMDSS equipment on vessels in Sea Area A1 and, where endorsed, other areas. The operator must work within its scope.

Radio watch in A1

A continuous watch on VHF Channel 16 and DSC Channel 70, plus reception of MSI by NAVTEX or another receiver, as required by SOLAS and the flag administration.

Radio log entries

Record all distress, urgency and safety communications, watch periods, equipment tests, battery checks and malfunctions, with times and the operator's signature.

GMDSS battery testing

Reserve batteries are checked regularly, typically weekly for voltage and electrolyte and annually for capacity, with terminals kept clean and all results recorded in the radio log.