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NIMASA GMDSS GOC Exam study materials
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NIMASA GMDSS GOC Exam practice questions

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Question 1GMDSS general principles, carriage requirements and functional elements

Under the GMDSS, which sea area is defined as being within radiotelephone coverage of at least one VHF coast station in which continuous DSC alerting is available?

  1. Sea Area A2
  2. Sea Area A3
  3. Sea Area A4
  4. Sea Area A1 Correct answer.

Explanation

Sea Area A1 is defined by the coverage of shore-based VHF coast stations providing continuous DSC alerting, roughly 20 to 30 nautical miles offshore. Each higher sea area adds further communication capability beyond A1.

Question 2GMDSS general principles, carriage requirements and functional elements

A vessel is certified to operate in Sea Area A3. Which minimum long-range alerting capability must it carry to satisfy that sea area?

  1. A NAVTEX receiver alone
  2. A 406 MHz EPIRB alone
  3. An MF/HF DSC watch on 2187.5 kHz only
  4. A recognised satellite service such as Inmarsat with continuous alerting Correct answer.

Explanation

Sea Area A3 is defined by continuous alerting through a recognised mobile-satellite service, so the ship must carry satellite communication equipment. An EPIRB or NAVTEX receiver supports distress and broadcast reception but does not by itself provide the two-way alerting that defines A3.

Question 3GMDSS general principles, carriage requirements and functional elements

Which equipment provides the fundamental GMDSS capability of transmitting a distress alert by satellite to a rescue coordination centre when the vessel sinks?

  1. SART
  2. 406 MHz float-free EPIRB Correct answer.
  3. Two-way VHF radiotelephone
  4. NAVTEX receiver

Explanation

A float-free 406 MHz EPIRB is designed to activate automatically on sinking and to relay the distress alert through the COSPAS-SARSAT system to a rescue coordination centre. The other items serve on-scene locating, broadcast reception or short-range communications.

Question 4GMDSS general principles, carriage requirements and functional elements

Which GMDSS functional element is served by the NAVTEX system?

  1. On-scene communications
  2. Bridge-to-bridge communications
  3. Transmission of maritime safety information Correct answer.
  4. Locating signals for search and rescue

Explanation

NAVTEX is a narrow-band direct-printing broadcast service that automatically receives maritime safety information such as navigational and meteorological warnings. It is a receive-only system and does not support two-way or locating functions.

Question 5GMDSS general principles, carriage requirements and functional elements

What is the primary purpose of the Digital Selective Calling facility in the GMDSS?

  1. To encrypt voice communications between ships
  2. To transmit automated alerts and establish contact on a specified channel or frequency Correct answer.
  3. To provide continuous position reporting to the flag State
  4. To broadcast meteorological forecasts to all stations

Explanation

DSC is an automated calling system that transmits a formatted alert containing the station identity and the channel or frequency to be used for subsequent communication. It is not an encryption system, a meteorological broadcast service, or a mandatory position-reporting system.

Question 6GMDSS general principles, carriage requirements and functional elements

Which document is issued to a GMDSS radio operator to certify competence and is normally required to operate the ship's radio installation?

  1. A GMDSS General Operator's Certificate Correct answer.
  2. A Ship Sanitation Control Certificate
  3. An International Load Line Certificate
  4. A Certificate of Registry

Explanation

The GMDSS General Operator's Certificate is the competence certificate for operators of GMDSS radio installations on ships required to comply with the SOLAS radio provisions. The other documents certify registration, load line assignment or health matters and have no bearing on radio operating competence.

Question 7GMDSS general principles, carriage requirements and functional elements

A ship operating only in Sea Area A1 may satisfy its GMDSS carriage requirements with a reduced fit. Which combination meets the minimum for A1?

  1. MF/HF DSC with radiotelephony, an EPIRB and a SART
  2. Inmarsat terminal with an EPIRB and a SART
  3. VHF DSC with radiotelephony, a 406 MHz EPIRB, a SART and a NAVTEX or other MSI receiver Correct answer.
  4. HF radiotelephony only, without any DSC equipment

Explanation

For Sea Area A1 the ship must be able to alert and communicate on VHF, carry satellite EPIRB and SART for distress and locating, and receive maritime safety information. MF/HF and satellite terminals become necessary only when the ship operates beyond VHF coast-station coverage.

Question 8GMDSS general principles, carriage requirements and functional elements

A vessel certified for Sea Areas A1, A2 and A3 loses its Inmarsat terminal through damage. Which action best preserves compliance with the GMDSS alerting requirement?

  1. Continue using VHF and MF DSC only and record the deficiency
  2. Arrange repair at the next port and, meanwhile, use the remaining approved means such as HF DSC where fitted Correct answer.
  3. Switch off the NAVTEX receiver to save power
  4. Rely solely on the 406 MHz EPIRB for routine communications

Explanation

When the primary satellite alerting capability is lost, the operator should arrange repair and use any remaining approved means of alerting, such as HF DSC, to maintain the required capability. Simply continuing without any long-range alerting leaves the ship non-compliant.

Question 9GMDSS general principles, carriage requirements and functional elements

What does the GMDSS concept of 'continuous watch' require of the radio operator on a ship at sea?

  1. Automatic monitoring of the relevant DSC frequencies and, where required, radiotelephone distress frequencies Correct answer.
  2. Physical listening on the radiotelephone distress frequency at all times
  3. Continuous transmission of a position report
  4. A watchkeeper standing by the EPIRB at all times

Explanation

The GMDSS relies on automatic receivers, such as DSC watch receivers and NAVTEX, to maintain continuous watch, with manual listening required on the radiotelephone distress and safety frequencies where the equipment does not provide it automatically. Physical listening at all times is not required where automatic arrangements exist.

Question 10GMDSS general principles, carriage requirements and functional elements

A distress alert is transmitted by DSC on VHF. Which frequency is used for the subsequent distress, urgency and safety radiotelephony communication?

  1. Channel 06
  2. Channel 70
  3. Channel 13
  4. Channel 16 Correct answer.

Explanation

DSC alerts on VHF are sent on Channel 70, and the follow-on radiotelephony communication is conducted on Channel 16, the VHF distress and calling frequency. Channel 70 is reserved for DSC and must not be used for voice.

Question 11GMDSS general principles, carriage requirements and functional elements

How does a SART assist a rescue operation?

  1. It transmits a distress alert to the satellite system
  2. It responds to radar interrogation with a series of dots on the searching vessel's radar display Correct answer.
  3. It provides encrypted voice communication with the rescue coordination centre
  4. It broadcasts weather warnings to nearby ships

Explanation

A SART is a radar transponder that, when interrogated by a searching vessel's radar, returns a distinctive series of dots that helps locate the survival craft. It does not transmit satellite alerts, broadcast weather, or provide secure voice.

Question 12GMDSS general principles, carriage requirements and functional elements

A small craft is fitted with a VHF DSC radio whose watch receiver is faulty. What is the most appropriate operational response in the context of GMDSS requirements?

  1. Arrange repair promptly and maintain a listening watch on Channel 16 in the interim Correct answer.
  2. Disable the DSC controller permanently and rely on Channel 13
  3. Ignore the fault because VHF is optional for all vessels
  4. Use Channel 70 for voice calls until repair is completed

Explanation

A faulty DSC watch receiver removes the automatic alerting watch, so the fault should be repaired promptly and the operator should compensate by maintaining a manual listening watch on the distress and calling frequency. Channel 70 is reserved for DSC and may not be used for voice.

Question 13GMDSS general principles, carriage requirements and functional elements

Which statement correctly describes the role of the Rescue Coordination Centre in the GMDSS?

  1. It broadcasts only commercial advertisements to shipping
  2. It manufactures the ship's radio equipment
  3. It coordinates the response to a distress alert and directs search and rescue assets Correct answer.
  4. It issues the ship's radio operator certificates

Explanation

The Rescue Coordination Centre receives distress alerts and coordinates the search and rescue response, tasking appropriate assets and communicating with the casualty. It does not manufacture equipment, issue operator certificates, or broadcast commercial traffic.

Question 14GMDSS general principles, carriage requirements and functional elements

Which of the following best describes the GMDSS functional element of 'alerting'?

  1. The reception of navigational warnings by the ship
  2. The transmission of a distress alert from the ship to a shore authority or rescue coordination centre Correct answer.
  3. The provision of a radar locating signal for search craft
  4. The transmission of routine business messages to the ship's agent

Explanation

Alerting is the ship-to-shore transmission of a distress alert to a shore authority or rescue coordination centre, which then initiates the rescue response. Reception of warnings, routine traffic and radar locating are separate functional elements.

Question 15GMDSS general principles, carriage requirements and functional elements

A vessel equipped for A1, A2 and A3 has just lost its NAVTEX receiver but retains all other equipment. Which functional element is directly affected?

  1. Bridge-to-bridge communications
  2. On-scene locating of the survival craft
  3. Reception of maritime safety information Correct answer.
  4. Transmission of distress alerts

Explanation

NAVTEX is a primary means of receiving maritime safety information, so its loss directly affects that functional element. Distress alerting, locating and bridge-to-bridge communication are provided by other equipment and are unaffected.

Question 16GMDSS general principles, carriage requirements and functional elements

Which factor determines whether a ship must be fitted with GMDSS equipment under the SOLAS radio provisions?

  1. The ship's cargo type only
  2. The age of the ship's radar only
  3. The nationality of the radio operator only
  4. The ship's size, voyage area and the applicable SOLAS chapter IV requirements Correct answer.

Explanation

The SOLAS radio provisions apply according to the ship's tonnage, the sea areas in which it operates and the applicable chapter IV requirements. Cargo type, operator nationality and radar age do not determine the GMDSS carriage obligation.

Question 17GMDSS general principles, carriage requirements and functional elements

A ship is fitted with an Inmarsat terminal, MF/HF DSC and VHF DSC. Why does the GMDSS still require an EPIRB?

  1. Because the EPIRB provides bridge-to-bridge communication
  2. Because the EPIRB replaces the NAVTEX receiver
  3. Because the EPIRB is the only device that can send a distress alert when the ship is abandoned and no other equipment is available Correct answer.
  4. Because the EPIRB is required to receive navigational warnings

Explanation

The float-free EPIRB provides an independent, automatic means of alerting when the vessel is abandoned or the main power and radio installation are lost. It does not receive warnings, provide bridge-to-bridge communication, or replace NAVTEX.

Question 18GMDSS general principles, carriage requirements and functional elements

A vessel is operating in an area where both Inmarsat coverage and MF coast-station coverage are available. Which statement about its GMDSS sea-area classification is correct?

  1. It must be classified as A2 because MF coverage exists
  2. It may be classified as A3 because it lies within Inmarsat coverage, regardless of whether A1 or A2 coverage also exists Correct answer.
  3. It cannot be classified into any sea area until it leaves the area
  4. It must be classified as A4 because both services overlap

Explanation

Sea areas are cumulative and defined by the highest service available: a ship within Inmarsat coverage is in A3, and the presence of A1 or A2 coverage does not lower that classification. A4 applies only where none of A1, A2 or A3 coverage exists.

Question 19GMDSS general principles, carriage requirements and functional elements

Which combination best describes the GMDSS functional elements that must be provided on a ship at sea, irrespective of the specific equipment fitted?

  1. Only bridge-to-bridge communications and position reporting
  2. Alerting, communications, locating, maritime safety information and bridge-to-bridge communications Correct answer.
  3. Only alerting and locating
  4. Only maritime safety information and routine traffic

Explanation

The GMDSS is built around a set of functional elements: distress alerting, distress and safety communications, on-scene communications and locating, reception of maritime safety information, and bridge-to-bridge communications. Any compliant installation must be able to provide all of them, whatever equipment is chosen.

Question 20GMDSS general principles, carriage requirements and functional elements

A vessel's 406 MHz EPIRB is inadvertently activated while alongside in port. What is the correct operational response?

  1. Switch it off and take no further action
  2. Transmit a mayday on Channel 16 to test the system
  3. Switch it off and immediately inform the relevant rescue coordination centre or coast station that it was a false alert Correct answer.
  4. Leave it transmitting until the battery is exhausted

Explanation

An inadvertent EPIRB activation must be stopped and the relevant rescue coordination centre or coast station informed at once so that an unnecessary search and rescue response is cancelled. Taking no action or leaving the beacon transmitting wastes rescue resources and may trigger a full response.

Question 21Radio propagation, frequencies and basic radio theory

In the maritime MF/HF bands, which propagation mechanism is chiefly responsible for long-distance communication beyond the ground-wave range?

  1. Tropospheric ducting along the sea surface
  2. Sky-wave propagation via refraction in the ionosphere Correct answer.
  3. Ground-wave propagation over the sea surface
  4. Line-of-sight propagation through the troposphere

Explanation

MF/HF signals at long range are returned to Earth when they are refracted by ionised layers in the ionosphere, producing sky waves. Ground waves are limited to relatively short distances and line-of-sight paths are blocked by the horizon, so neither explains intercontinental HF working.

Question 22Radio propagation, frequencies and basic radio theory

Which frequency band offers the most reliable medium-range ship-to-shore communication using ground-wave propagation, independent of ionospheric conditions?

  1. VHF around 156 MHz
  2. MF around 2 MHz Correct answer.
  3. UHF around 450 MHz
  4. HF around 21 MHz

Explanation

MF around 2 MHz supports stable ground-wave propagation over hundreds of nautical miles, which is why the 2182 kHz distress watch and MF radiotelephony rely on it. Higher bands do not give a comparable surface-following ground wave.

Question 23Radio propagation, frequencies and basic radio theory

A GMDSS operator finds that reception on the 8 MHz maritime band is strong at night but fades out during daylight. What is the most likely cause?

  1. The D-layer absorbing sky waves during daylight hours Correct answer.
  2. The ground wave being blocked by daylight
  3. The ionosphere disappearing during daylight hours
  4. The antenna becoming detuned by sunlight

Explanation

Solar radiation increases ionisation in the D-layer, which absorbs HF sky waves passing through it and raises the usable frequency. At night the D-layer largely disappears, so lower frequencies like 8 MHz propagate better.

Question 24Radio propagation, frequencies and basic radio theory

Why does the maximum usable frequency (MUF) for a given HF path rise during daylight and fall at night?

  1. Because the sea surface becomes more reflective in sunlight
  2. Because solar ionisation increases the electron density of the layers, allowing higher frequencies to be refracted back to Earth Correct answer.
  3. Because radio horizon distance increases at night
  4. Because the Earth's magnetic field strengthens during the day

Explanation

Higher electron density raises the plasma frequency of the ionospheric layers, so higher frequencies can still be bent back to Earth. After sunset the layers weaken and the MUF falls, which is why operators shift to lower HF bands at night.

Question 25Radio propagation, frequencies and basic radio theory

A ship's VHF range to a coast station is limited by the radio horizon. Which factor most directly determines that range?

  1. The state of the tide
  2. The frequency of the ionospheric layer
  3. The ionospheric electron density
  4. The antenna heights of the ship and coast station Correct answer.

Explanation

VHF is essentially line-of-sight, so the radio horizon is set mainly by the heights of the two antennas and the curvature of the Earth. Raising either antenna extends the path beyond the geometric horizon.

Question 26Radio propagation, frequencies and basic radio theory

Which statement correctly describes the relationship between wavelength, frequency and the speed of radio waves in free space?

  1. Wavelength equals frequency multiplied by the speed of light
  2. Wavelength equals the speed of light divided by frequency Correct answer.
  3. Wavelength equals frequency divided by the speed of light
  4. Wavelength is independent of frequency

Explanation

For any wave, wavelength equals velocity divided by frequency; for radio waves the velocity is about 300,000,000 metres per second. This is why 156 MHz corresponds to a wavelength of roughly two metres.

Question 27Radio propagation, frequencies and basic radio theory

An operator needs to know the approximate free-space wavelength of a 2,182 kHz distress transmission. Which value is closest?

  1. About 14 metres
  2. About 1.4 metres
  3. About 1,370 metres
  4. About 137 metres Correct answer.

Explanation

Using wavelength = 300 divided by frequency in MHz, 2.182 MHz gives about 137 metres. This long wavelength explains why MF antennas are physically large and why ground-wave propagation is effective at this frequency.

Question 28Radio propagation, frequencies and basic radio theory

What is meant by the 'skip zone' on an HF sky-wave circuit?

  1. The zone in which the ionosphere absorbs all signals
  2. The area covered by the ship's VHF radio horizon
  3. The area where the ground wave is strongest
  4. The region between the limit of the ground wave and the nearest point where the sky wave returns to Earth Correct answer.

Explanation

The skip zone is a ring of silence around the transmitter where the ground wave has faded but the sky wave has not yet returned to Earth. Operators overcome it by changing frequency or using a different propagation angle.

Question 29Radio propagation, frequencies and basic radio theory

During a period of very high sunspot activity, why may an operator prefer a higher HF band such as 16 or 22 MHz for a long-haul circuit?

  1. Because the D-layer thickens and absorbs higher frequencies less than lower ones in absolute terms
  2. Because the ground wave extends further at high frequencies
  3. Because the MUF rises, so higher frequencies propagate with less absorption and better reliability Correct answer.
  4. Because lower frequencies are completely absorbed by seawater

Explanation

High solar activity raises ionisation and therefore the MUF, so higher HF bands can support the path while avoiding the heavy absorption that lower frequencies suffer. Operators select the highest frequency that still supports the circuit.

Question 30Radio propagation, frequencies and basic radio theory

What is the primary reason for using single-sideband (SSB) suppressed-carrier radiotelephony rather than full-carrier AM on MF/HF maritime channels?

  1. It makes the signal immune to ionospheric fading
  2. It removes the need for an antenna
  3. It concentrates power in one sideband, improving efficiency and reducing bandwidth Correct answer.
  4. It allows the use of simpler receivers

Explanation

SSB suppresses the carrier and one sideband, so the available transmitter power is concentrated in the information-bearing sideband and the occupied bandwidth is halved. This gives more effective communication within the narrow maritime channel spacing.

Question 31Radio propagation, frequencies and basic radio theory

Which ITU radio emission designation letter indicates a single-sideband, suppressed-carrier telephony emission?

  1. J Correct answer.
  2. F
  3. A
  4. H

Explanation

In the ITU emission designation, J denotes single-sideband with suppressed carrier, while H denotes single-sideband with full carrier. The first symbol of the designation describes the modulation of the main carrier.

Question 32Radio propagation, frequencies and basic radio theory

Which factor most affects the choice of HF frequency for a ship-to-shore circuit at a given time of day?

  1. The type of battery charger in use
  2. The distance to the coast station and the current ionospheric conditions Correct answer.
  3. The colour of the antenna insulators
  4. The number of crew on watch

Explanation

HF frequency selection depends on path length and the state of the ionosphere, since the MUF and lowest usable frequency change with distance and time of day. The operator picks a frequency between these limits for reliable sky-wave working.

Question 33Radio propagation, frequencies and basic radio theory

What is the effect of the ionospheric D-layer on MF and lower HF signals during daylight?

  1. It absorbs signal energy, increasing attenuation Correct answer.
  2. It reflects signals back to Earth with almost no loss
  3. It converts vertical polarisation to horizontal
  4. It shifts the frequency of the signal

Explanation

The D-layer is a region of relatively dense ionisation at low altitude where collisions cause energy loss, so signals passing through it are absorbed. This absorption is strongest by day and at lower frequencies, which is why daytime MF and low-HF ranges are reduced.

Question 34Radio propagation, frequencies and basic radio theory

A GMDSS operator notes that a DSC call on 2,187.5 kHz is received at long range by day but the same channel is noisy and unreliable at night. Which explanation best fits this observation?

  1. At night the transmitter power automatically increases
  2. At night atmospheric noise and interference rise while sky-wave signals from distant stations may also arrive, degrading the channel Correct answer.
  3. At night the ground wave is strengthened by the ionosphere
  4. At night the antenna becomes directional towards the coast

Explanation

MF channels suffer more atmospheric noise at night, and distant sky-wave signals can also propagate into the area, raising interference on the distress and DSC frequencies. The ground wave itself is not strengthened by the ionosphere, so the daytime advantage reflects lower noise rather than better ground-wave coupling.

Question 35Radio propagation, frequencies and basic radio theory

An operator planning an HF sky-wave circuit notices that the signal is being received at unusually low elevation angles with strong fading. Which change would most improve circuit reliability while preserving the long-haul path?

  1. Selecting a frequency nearer the LUF so the wave is absorbed before it reaches the receiving station
  2. Selecting a frequency closer to the MUF so the wave penetrates less and returns at a higher angle
  3. Raising the antenna and using a higher take-off angle to shorten the hop distance
  4. Selecting a frequency well below the MUF so the wave returns at a lower angle with a shorter hop Correct answer.

Explanation

Lowering the operating frequency relative to the MUF increases ionospheric refraction, so the wave bends down sooner, giving a lower take-off and arrival angle and a shorter hop, which usually reduces multipath fading. The frequency must still stay above the LUF so absorption does not become excessive.

Question 36Radio propagation, frequencies and basic radio theory

A GMDSS operator is planning an HF radiotelephony circuit and wants to reduce the effect of multipath fading caused by sky-wave signals arriving via slightly different ionospheric paths. Which measure is most appropriate?

  1. Use amplitude modulation (AM) instead of single-sideband (SSB).
  2. Increase the transmitter power to override the fading.
  3. Use a directional antenna with a narrow beamwidth aimed at the elevation angle of the desired path. Correct answer.
  4. Switch to a lower frequency band where fading is less pronounced.

Explanation

Multipath fading occurs when sky-wave signals reach the receiver via slightly different ionospheric paths and interfere. A directional antenna with a narrow beamwidth discriminates against off-angle arrivals, reducing the number of interfering paths and thus fading. Increasing power does not remove the phase cancellation, and changing frequency or modulation does not directly address the multipath geometry.

Question 37VHF and MF/HF radiotelephony including DSC

On a VHF DSC controller, what does pressing and holding the DISTRESS button for about five seconds achieve when no nature of distress has been selected?

  1. It performs a radio check on channel 16
  2. It transmits an undesignated distress alert on channel 70 Correct answer.
  3. It silences the DSC audible alarm without transmitting
  4. It opens the routine call menu for a ship-to-shore call

Explanation

Holding the dedicated distress key produces a distress alert that is sent automatically on VHF channel 70. If the operator has not chosen a nature of distress, the alert is transmitted as undesignated. The alert contains the MMSI and position but no nature code.

Question 38VHF and MF/HF radiotelephony including DSC

Which frequency band does the GMDSS reserve for MF digital selective calling?

  1. 406.037 MHz
  2. 8414.5 kHz
  3. 156.525 MHz
  4. 2187.5 kHz Correct answer.

Explanation

The MF distress and safety DSC frequency is 2187.5 kHz, used for alerting within the MF coverage range. 8414.5 kHz is an HF DSC channel, 156.525 MHz is VHF channel 70, and 406 MHz belongs to the COSPAS-SARSAT EPIRB system.

Question 39VHF and MF/HF radiotelephony including DSC

What is the correct radiotelephony distress call and the frequency on which it is normally transmitted in the MF/HF service?

  1. SECURITE repeated three times, on 2174.5 kHz
  2. MAYDAY repeated once, on 8291 kHz
  3. PAN PAN repeated three times, on 2182 kHz
  4. MAYDAY repeated three times, on 2182 kHz Correct answer.

Explanation

The distress call consists of MAYDAY spoken three times, followed by the vessel name and callsign, and is sent on the MF distress and safety voice frequency 2182 kHz. PAN PAN is urgency and SECURITE is safety. 8291 kHz is an HF distress and safety voice frequency used when MF is unsuitable.

Question 40VHF and MF/HF radiotelephony including DSC

A VHF DSC controller displays the message "Individual call received" from a coast station. What is the standard operator action?

  1. Broadcast a MAYDAY RELAY on channel 16 before responding
  2. Acknowledge on the DSC controller, then switch to the proposed working channel for the voice or data link Correct answer.
  3. Retransmit the same call back to the coast station on channel 70
  4. Ignore the call because individual calls need no acknowledgement

Explanation

An individual DSC call proposes a working channel, and the called station acknowledges automatically or manually on the DSC controller. The parties then move to the indicated radiotelephony or data channel to conduct the traffic. Channel 70 is never used for the voice conversation itself.

Question 41VHF and MF/HF radiotelephony including DSC

Why must VHF channel 70 never be used for voice communication?

  1. It is a simplex channel limited to one watt of output power
  2. It is allocated to port operations and is monitored only by tugs
  3. It is reserved exclusively for DSC and voice traffic would interfere with digital alerting Correct answer.
  4. It carries the automatic identification system data broadcast

Explanation

Channel 70 (156.525 MHz) is dedicated worldwide to digital selective calling. Voice transmissions on it would disrupt DSC alerts, including distress alerts, from other stations. Voice traffic is conducted on channel 16 or a suitable working channel after the DSC exchange.

Question 42VHF and MF/HF radiotelephony including DSC

Which information must a distress alert transmitted by MF/HF DSC contain to be most useful to a rescue coordination centre?

  1. The vessel's port of registry and next port of call
  2. The vessel's MMSI, the nature of distress and the position with time of update Correct answer.
  3. The number of crew on board and their nationalities
  4. The vessel's cargo manifest and the master's name

Explanation

A DSC distress alert is built around the ship's MMSI, the selected nature of distress and the position with its time of update. These allow the rescue coordination centre to identify the vessel and know where to search. Additional details are passed later by radiotelephony.

Question 43VHF and MF/HF radiotelephony including DSC

A vessel receives a DSC distress alert on 2187.5 kHz from a ship known to be more than 200 nautical miles away. What is the recommended action?

  1. Acknowledge by voice on 2182 kHz and request the vessel's cargo details
  2. Do not acknowledge; remain on watch and await a distress relay or further information Correct answer.
  3. Acknowledge immediately by DSC and proceed towards the vessel
  4. Retransmit the alert on all HF DSC frequencies to widen the search

Explanation

Stations far from the distressed vessel should not acknowledge an MF distress alert, because acknowledgement is the responsibility of ships and coast stations in the vicinity. Acknowledging from long range can prevent closer stations from responding and can mislead the rescue coordination centre. The correct action is to keep watch for a relay.

Question 44VHF and MF/HF radiotelephony including DSC

What does the DSC "enhanced position" or "position request" function on a VHF installation allow a station to do?

  1. Increase transmitter output power above the normal limit
  2. Switch the transceiver to the distress and safety frequency automatically
  3. Record all voice traffic on channel 16 for later playback
  4. Request another station's position or send its own position automatically over the air Correct answer.

Explanation

Some DSC controllers can request the position of another station or send their own position automatically. This supports fleet tracking and search and rescue coordination. The function does not change transmitter power or channel selection.

Question 45VHF and MF/HF radiotelephony including DSC

When is a MAYDAY RELAY transmitted by a station other than the vessel in distress?

  1. When a distress alert has been received from a vessel that cannot transmit its own distress message Correct answer.
  2. Only after the rescue coordination centre has closed the distress
  3. Whenever a distress alert is received on any DSC frequency
  4. When a vessel wishes to test its distress equipment

Explanation

A MAYDAY RELAY is sent when a station learns that another vessel is in distress and that vessel cannot transmit its own distress message, or when a distress alert needs relaying. It is not a routine response to every alert. Testing distress equipment is never done with a distress call.

Question 46VHF and MF/HF radiotelephony including DSC

What is the purpose of the DSC "test" call between two stations?

  1. To verify the accuracy of the vessel's EPIRB registration
  2. To measure the transmitter output power in watts
  3. To check the battery voltage of the survival craft radio
  4. To confirm that the DSC link and the proposed working channel function correctly without alerting rescue authorities Correct answer.

Explanation

The DSC test call checks that the equipment can reach another station and that the suggested working channel is usable. It is addressed to a specific station and does not involve the distress or safety services. It should not be confused with a distress alert or an EPIRB test.

Question 47VHF and MF/HF radiotelephony including DSC

During a distress traffic on 2182 kHz, a coast station transmits the proword SILENCE. What does this require other stations to do?

  1. Repeat the distress message on the next HF channel
  2. Stop transmitting immediately and maintain radio silence until the coast station cancels it Correct answer.
  3. Change to channel 16 and continue the conversation there
  4. Increase transmitter power to overcome interference

Explanation

SILENCE imposes radio silence on the frequency so that the controlling station can manage the distress traffic. All stations except those involved in the distress cease transmitting. The silence is lifted by the proword SILENCE FINI.

Question 48VHF and MF/HF radiotelephony including DSC

In the MF/HF radiotelephony service, which statement correctly describes the use of the frequency 8291 kHz?

  1. It is the primary MF distress frequency for all vessels
  2. It is an HF distress and safety voice frequency used when MF communication is not possible Correct answer.
  3. It is a ship-to-shore public correspondence channel
  4. It is the VHF channel used for bridge-to-bridge navigation

Explanation

8291 kHz is one of the HF radiotelephony distress and safety frequencies and is used when MF does not provide the required range. The primary MF distress voice frequency is 2182 kHz. Public correspondence uses separate commercial channels, and VHF bridge-to-bridge uses channel 13.

Question 49VHF and MF/HF radiotelephony including DSC

A vessel's VHF DSC controller is set to the correct channel but the position shown is several hours old. What should the operator do before sending a distress alert?

  1. Send the alert anyway because the position field is optional
  2. Switch to channel 16 and make a voice distress call instead of using DSC
  3. Update the position manually or confirm the GPS input is working, then transmit Correct answer.
  4. Reset the controller to factory defaults to refresh the position

Explanation

An out-of-date position reduces the value of the distress alert and can send rescuers to the wrong place. The operator should confirm that the GPS input is functioning or enter the position manually before transmitting. Only then should the alert be sent.

Question 50VHF and MF/HF radiotelephony including DSC

What is the correct response of a ship station that receives a DSC distress alert on VHF channel 70 while in a position to assist?

  1. Acknowledge the alert by DSC, then listen on channel 16 and prepare to assist Correct answer.
  2. Acknowledge by voice on channel 70 and ask for the nature of distress
  3. Ignore the alert and continue normal working on channel 16
  4. Broadcast a SECURITE message on channel 16 to warn other vessels

Explanation

A station in a position to assist should acknowledge the DSC distress alert on the DSC controller and then keep watch on channel 16 for the distress traffic. Voice communication is never conducted on channel 70. The rescue coordination centre is informed of the assistance offered.