Marine Communications and GMDSS Flashcards

What is the international distress, safety, and calling frequency on VHF radio?

Answer: Channel 16

VHF Channel 16 (156.8 MHz) is the international distress, safety, and calling frequency required to be monitored by all vessels at sea.

What does GMDSS stand for?

Answer: Global Maritime Distress and Safety System

GMDSS stands for Global Maritime Distress and Safety System, the international radio communications framework for maritime safety established under SOLAS.

Which EPIRB type is float-free, automatically activated, and transmits on 406 MHz via satellite?

Answer: Category I 406 MHz EPIRB

Category I 406 MHz EPIRBs are float-free, automatically activate when submerged, and use the COSPAS-SARSAT satellite system to transmit distress signals.

Which VHF channel is designated exclusively for Digital Selective Calling (DSC) distress alerts?

Answer: Channel 70

VHF Channel 70 is reserved exclusively for Digital Selective Calling (DSC) and must not be used for voice communications.

What is the primary purpose of a NAVTEX receiver aboard a vessel?

Answer: Receiving navigational warnings, weather forecasts, and urgent maritime safety information

NAVTEX is an international automated direct-printing service that receives navigational warnings, meteorological forecasts, and urgent maritime safety information on MF frequencies.

Which signal word indicates an urgency message in maritime radio communications?

Answer: PAN-PAN

PAN-PAN (spoken three times) is the urgency signal used when a vessel has a serious situation requiring assistance but is not in immediate life-threatening danger.

How often must GMDSS operators test DSC equipment to ensure its readiness?

Answer: Daily

GMDSS regulations require daily testing of DSC equipment to verify proper function and ensure the system is operational in an emergency.

Which GMDSS Sea Area is defined as within VHF shore-based DSC coverage, typically within 20-30 miles of shore?

Answer: Sea Area A1

Sea Area A1 is defined as the area within range of VHF shore-based DSC stations, generally within 20-30 nautical miles of the coast.

What is the function of a SART (Search and Rescue Transponder)?

Answer: Locating survival craft by responding to X-band radar pulses

A SART responds to X-band (9 GHz) radar pulses from searching vessels or aircraft, displaying a series of dots on the radar screen to pinpoint the location of survivors.

What is the primary purpose of two-way VHF portable radios required in survival craft under GMDSS?

Answer: On-scene communications between survivors and rescue units

Two-way VHF portable radios in survival craft are used for on-scene communications between survivors and SAR rescue units during rescue operations.

What does the COSPAS-SARSAT system primarily do?

Answer: Detects and locates 406 MHz emergency beacons including EPIRBs and PLBs

COSPAS-SARSAT is an international satellite-based search and rescue system that detects and locates distress signals from 406 MHz emergency beacons.

Which frequency band does NAVTEX use for international maritime safety broadcasts?

Answer: MF (518 kHz and 490 kHz)

NAVTEX operates on medium frequency, primarily 518 kHz for international broadcasts in English and 490 kHz for national language broadcasts.

What vessel identifier is automatically transmitted when a DSC distress alert is sent?

Answer: The vessel's MMSI number

A DSC distress alert automatically transmits the vessel's unique 9-digit MMSI number along with the nature of distress and GPS position when connected.

What is the watch-keeping requirement for VHF Channel 16 on GMDSS-equipped vessels while at sea?

Answer: Continuous watch while at sea

GMDSS vessels must maintain continuous watch on VHF Channel 16 while at sea because it is the international distress and calling frequency.

What is the correct sequence for initiating a voice MAYDAY distress call?

Answer: MAYDAY three times, vessel name three times, MAYDAY once, position, nature of distress, persons aboard, other relevant information

The correct MAYDAY procedure begins with 'MAYDAY MAYDAY MAYDAY,' followed by the vessel's name three times, then 'MAYDAY' once more, then position, nature of distress, number of persons, and any other pertinent information.

Which signal word announces a safety message regarding navigational hazards or important meteorological warnings?

Answer: SECURITE

SECURITE (pronounced 'say-cure-ee-tay,' spoken three times) is the safety signal used to precede announcements about navigational hazards, ice reports, or meteorological warnings.

How many digits make up a vessel's MMSI (Maritime Mobile Service Identity) number?

Answer: 9 digits

An MMSI is a unique 9-digit number assigned to a vessel or coast station, used in DSC and AIS systems for identification.

Under USCG and SOLAS regulations, how often must an EPIRB battery be replaced and its hydrostatic release be serviced?

Answer: Every 2 years

EPIRB batteries and hydrostatic releases must be replaced or serviced every 2 years, or by the expiration date printed on the unit, whichever comes first.

What communication systems are required for GMDSS vessels operating in Sea Area A3, beyond MF range but within INMARSAT satellite coverage?

Answer: MF/HF radio or INMARSAT satellite communications

Sea Area A3 vessels must carry MF/HF radio capable of DSC on relevant frequencies and/or INMARSAT satellite equipment to ensure distress alerting capability beyond coastal waters.

What information must be programmed into a vessel's DSC controller before it can function properly?

Answer: The vessel's MMSI number, and ideally a GPS connection for automatic position updates

The vessel's MMSI number must be programmed into the DSC controller; a GPS interface should also be connected so position is automatically included in any distress alert.