GOC GMDSS Exam flashcards

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

MAYDAY

Spoken radiotelephony distress signal indicating a vessel or person is in grave and imminent danger and requires immediate assistance; has absolute priority over all other communications.

PAN PAN

Urgency signal used when a vessel or person is in need of assistance but not in immediate danger, such as medical advice or a breakdown without immediate risk.

SÉCURITÉ

Safety signal used to announce important navigational or meteorological warnings, or the transmission of maritime safety information; lower priority than distress and urgency.

MAYDAY RELAY

Procedure used by a station other than the one in distress to transmit a distress message on its behalf, for example when relaying an EPIRB activation.

Sea area A1

Sea area covered by VHF coast stations with continuous DSC alerting, approximately 20 to 30 nautical miles from the coast.

Sea area A2

Sea area covered by MF coast stations with continuous DSC alerting, excluding A1, typically extending about 100 to 150 nautical miles offshore.

Sea area A3

Sea area covered by an Inmarsat geostationary satellite with continuous alerting, excluding A1 and A2, roughly between 70 degrees north and 70 degrees south.

Sea area A4

Remaining sea areas outside A1, A2 and A3, mainly polar regions, requiring HF DSC and HF radiotelephony for distress alerting and watchkeeping.

GMDSS functional requirements

Alerting, search and rescue coordination, on-scene communications, locating, maritime safety information, and general radiocommunications including bridge-to-bridge.

VHF Ch 70

Dedicated VHF digital selective calling channel used only for DSC distress, urgency, safety and routine alerts; voice transmission is not permitted on this channel.

MF DSC frequency

2187.5 kHz is the MF digital selective calling distress and safety frequency, paired with 2182 kHz for MF radiotelephony distress and calling.

HF DSC frequencies

4207.5, 6312, 8414.5, 12577 and 16804.5 kHz are the HF DSC distress and safety frequencies used for alerting and watchkeeping in sea area A4.

MMSI structure

Maritime Mobile Service Identity: ship stations use MID plus six digits; coast stations use 00 plus MID plus four digits; group stations use 0 plus MID plus five digits.

DSC distress alert contents

Includes format specifier, nature of distress, position, time, and telecommand indicating the subsequent communication mode, usually radiotelephony.

Inmarsat-C

Store-and-forward satellite messaging terminal with an omnidirectional antenna that supports distress priority alerting and enhanced group call reception for MSI.

SafetyNET

Inmarsat enhanced group call service that delivers maritime safety information, including navigational and meteorological warnings, to ships in ocean areas and NAVAREAs.

COSPAS-SARSAT

Satellite system that detects and locates 406 MHz EPIRB distress signals, providing global coverage including polar regions outside Inmarsat coverage.

Inmarsat ocean regions

Atlantic Ocean Region East and West, Indian Ocean Region, and Pacific Ocean Region; a terminal must be logged into the correct region for service.

NAVTEX frequency

518 kHz is the international NAVTEX frequency for English broadcasts; 490 kHz is used for national language broadcasts; coverage is typically 200 to 300 nautical miles.

NAVTEX message types

B2 character identifies message type: A navigational, B meteorological, C ice, D search and rescue, and others for specific warning categories.

NAVAREA and METAREA

Geographic areas established for coordinating navigational warnings (NAVAREA) and meteorological information (METAREA) under the World-Wide Navigational Warning Service.

406 MHz EPIRB

Emergency position-indicating radio beacon transmitting a digital distress message with vessel identity and, if GPS-equipped, position to the COSPAS-SARSAT satellite system.

121.5 MHz homing

Frequency transmitted by an EPIRB to allow search and rescue aircraft and vessels to home in on the beacon for locating the survivor.

SART

Search and rescue transponder operating on 9 GHz X-band radar, producing a series of dots on a radar display to indicate the survivor's position.

AIS-SART

Device transmitting AIS messages indicating a SART in distress, displayed on AIS-equipped vessels and shore stations; it does not produce a radar response.

HF frequency selection

Use higher HF frequencies during daylight and lower frequencies at night, governed by the maximum usable frequency and lowest usable frequency for the path.

VHF radio horizon

Approximate line-of-sight range in nautical miles equals 4.12 times the square root of antenna height in metres, plus the same for the other station.

Standing wave ratio

SWR indicates antenna system matching; a low value, ideally below 1.5 to 1, shows good matching, while a high value indicates a fault.

Reserve source of energy

Independent battery supply for the radio installation, required for at least one hour, or six hours when no emergency generator is fitted.

Battery capacity test

Discharge test at the manufacturer's specified rate; the battery should deliver at least 80 percent of its rated capacity to remain acceptable.

GMDSS radio log

Record of distress, urgency and safety communications, equipment tests, position reports and watchkeeping details, retained as required by the flag state.

GMDSS operator certificates

General Operator's Certificate covers all sea areas A1 to A4; Restricted Operator's Certificate covers A1 only; the certificate must be carried on board.