STCW Communication Systems 4 — Questions and Answers
Question 1: What does 'MMSI' stand for in the context of maritime communications?
- Marine Mobile Satellite Identifier
- Maritime Mobile Service Identity (Correct answer)
- Marine Messaging and Signal Index
- Maritime Management and Safety Inspection
Correct answer: Maritime Mobile Service Identity
MMSI stands for Maritime Mobile Service Identity, a unique nine-digit number assigned to a ship's radio station for DSC and AIS identification.
Question 2: On which VHF channel should a vessel call a US port authority or vessel traffic service?
- Channel 6
- Channel 12 or 14 (Correct answer)
- Channel 22A
- Channel 70
Correct answer: Channel 12 or 14
VHF Channels 12 and 14 are commonly used by US port authorities and vessel traffic services (VTS) for ship movement coordination.
Question 3: What is the significance of the 'silence period' observed twice each hour on 2182 kHz?
- Equipment testing and calibration window
- Three-minute periods reserved for listening for distress signals (Correct answer)
- Scheduled broadcast of weather bulletins
- Mandatory rest period for radio operators
Correct answer: Three-minute periods reserved for listening for distress signals
At H+00 and H+30, a three-minute radio silence is observed on 2182 kHz so that weak distress signals can be heard without interference.
Question 4: A vessel in Sea Area A2 must carry which mandatory GMDSS equipment in addition to Sea Area A1 equipment?
- INMARSAT-C terminal
- MF DSC radio capable of transmitting on 2187.5 kHz (Correct answer)
- HF SSB radio with DSC on all distress frequencies
- AIS Class A transponder
Correct answer: MF DSC radio capable of transmitting on 2187.5 kHz
Sea Area A2 extends MF coverage, requiring an MF DSC radio able to transmit distress alerts on 2187.5 kHz and watch on 2182 kHz.
Question 5: What is the purpose of AIS (Automatic Identification System) in maritime communications?
- To encrypt vessel position data from unauthorized users
- To automatically broadcast vessel identity, position, course, and speed to nearby ships and coast stations (Correct answer)
- To replace VHF radio for all ship-to-ship communications
- To activate distress alerts when a vessel exceeds safe speed limits
Correct answer: To automatically broadcast vessel identity, position, course, and speed to nearby ships and coast stations
AIS continuously broadcasts vessel identity, position, course, speed, and other data, enhancing situational awareness and collision avoidance.
Question 6: Which distress signal procedure is correct when making a MAYDAY call on VHF Channel 16?
- Transmit once, then switch to Channel 6 for response
- Say 'MAYDAY' three times, vessel name three times, then give position and nature of distress (Correct answer)
- Activate DSC first, then wait 15 minutes before voice transmission
- Request permission from the coast guard before transmitting MAYDAY
Correct answer: Say 'MAYDAY' three times, vessel name three times, then give position and nature of distress
The correct procedure is to say 'MAYDAY MAYDAY MAYDAY' followed by the vessel name three times, then position, nature of distress, persons aboard, and any other relevant information.
Question 7: What is the role of a Radio Medical Advice (MEDICO) call in maritime communications?
- To request emergency evacuation of a critically ill seafarer
- To obtain medical guidance from a shore-based physician for treating a sick or injured person at sea (Correct answer)
- To report a medical emergency to the International Maritime Organization
- To activate the GMDSS urgency signal PAN-PAN
Correct answer: To obtain medical guidance from a shore-based physician for treating a sick or injured person at sea
A MEDICO call connects the ship to a shore-based medical authority that can provide treatment guidance for medical emergencies when evacuation is not immediately possible.
STCW Communication Systems 4
What does 'MMSI' stand for in the context of maritime communications?