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Unit 2

Distress,Urgency and Safety Services

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2.1 GMDSS General Provisions Global Maritime Distress and Safety System

(GMDSS) was set up to provide an international communications network to assist vessels in distress. All distress communications in the maritime mobile service by radiotelephony, digital selective calling and satellite whether and/or direct printing telegraphy (telex), must be conducted strictly in accordance with the correct procedures.

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This ensures that vessels in distress obtain help without delay. Ships equipped for and operating under GMDSS conditions are obliged to comply with chapter New (IX) of the ITU Radio Regulations. Some provisions of this chapter also apply to the aeronautical mobile service except in the case of special arrangements between the governments concerned. However, stations of the maritime mobile service when equipped to conform to chapter IX of the ITU Radio Regulations, shall comply with the provisions of that chapter.

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The procedures specified in chapter New (IX) of the ITU Radio Regulations are obligatory in the maritime mobile satellite service and for communications between stations on board aircraft and stations of the maritime mobile satellite service, wherever this service or stations of this service are specifically mentioned.

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The International Convention for the Safety of Life at Sea (SOLAS) , 1974, prescribes which ships and which of their survival craft shall be provided with radio equipment, and which ships shall carry portable radio equipment for use in survival craft.

Although the procedures are obligatory for all stations using communications in the maritime mobile and maritime mobile satellite service, they do allow:

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(a) Mobile Earth Stations (MESs) in distress to use any means at their disposal to attract attention, make known their position and obtain help;

(b) Any stations whether mobile (ship/aircraft) or land stations or coast stations involved in search and rescue duties to use, in exceptional circumstances, any means at their disposal to assist a mobile station or a mobile earth station in distress;

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(c) Any land (or coast station) or LES may use, in exceptional circumstances, any means at their disposal to assist a mobile station or MES in distress.

When transmitting distress, urgency or safety messages by radiotelephony, transmissions should be made slowly and distinctly with clear pronunciation. The use of the International Code of Signals is recommended, including the use of abbreviations and the phonetic alphabet, particularly in situations where language difficulties exist.

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For instance:

I have a male aged 40 years, patient has been ill for 6 hours, patient is in pain of whole chest, temperature is falling, the pulse is weak, patient appears to be in a state of shock.

MAJ40 MAN6 MDF91 MBW MCB MCW( karte-four nada-zero soxi-six nove-nine una-one)

Fan Yaotian:

Foxtrot Alfa November Yankee Alfa Oscar Tango India Alfa November

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Mobile stations may communicate with aircraft for safety purposes, but they must use the approved frequencies and observe the correct procedures. Aircraft which are required by national or international regulations to communicate with maritime mobile stations for safety purposes must comply with GMDSS provisions. Therefore until the full implementation of GMDSS, they must be able to transmit and receive:

(a) class J3E emissions on carrier frequencies 2182kHz and 4125 kHz; (b) class G3E emissions on Channel 16 VHF and optionally Channel 6 VHF.

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2. 1. 1 Distress Frequencies Within GMDSS a number of frequencies are

specifically allocated for distress communication purposes depending on the communication medium being used. These frequencies should be used by ships, aircraft or survival craft when seeking assistance in the maritime mobile service. They should be used for the distress call and distress traffic and for calls preceded by either the urgency signal or the safety signal.

DSC, radiotelephone and telex distress and safety frequencies are listed below.

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Table 2-1Band DSC RT Telex

MF 2 187.5 kHz 2 182 kHz 2 174. 5 kHz.

HF 4 MHz 4 207. 5 kHz 4 125 kHz 4 177.5 kHz

HF 6 MHz 6 312 kHz 6 215 kHz 6 268 kHz

HF 8 MHz 8 414. 5 kHz 8 291 kHz 8 376. 5 kHz

HF 12 MHz 12 577 kHz 12 290 kHz 12 520 kHz

HF 16 MHz 16 804. 5 kHz 16 420 kHz 16 695 kHz

VHF Channel 70 Channel 16

 

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The frequency 4125 kHz may be used by aircraft engaged in search and rescue (SAR) operations for distress/safety communications to stations in the maritime mobile service.

2182 kHz is used as the international distress and safety frequency and also for international call and reply at the present time. However with the full implementation of GMDSS 2182 kHz is likely to be used exclusively for distress and safety purposes.

The aeronautical frequencies 3023kHz and 5680kHz are used for intercommunication purposes between mobile stations and to participating land stations during coordinated SAR operations.

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2.1.2 Aeronautical Frequencies In the aeronautical VHF radiotelephony service (1

17.976 MHz~137MHz) the emergency frequency is 121. 5 MHz. Survival craft can also use this frequency for distress and urgency communications. Additionally this frequency may be used in the COSPAS-SARSAT emergency location system by emergency position-indicating radio beacons (EPIRBs) for distress alert transmissions to the satellite.

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The auxiliary aeronautical frequency of 123.1 MHz is used by the service and by other mobile and land stations engaged in coordinated SAR operations. Maritime mobile stations may communicate with aeronautical stations on 121.5 MHz and 243MHz for distress and urgency purposes only and on 123.1MHz for coordinated SAR operations. Class A3E emissions are used on these frequencies.

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2.1.3 GMDSS VHF Channel Usage Channel 6 VHF

Used for communication between ships and aircraft for coordinated SAR operations. May also be used by aircraft to communicate to ships for safety purposes.

Channel 13 VHF

Used for ship to ship communication relating to safety of navigation.

Digital Selective Calling RadioDigital Selective Calling Radio

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Channel 16 VHF

Used for distress and safety traffic on RT, may also be used by aircraft for safety purposes.

Channel 70 VHF

Used as a DSC distress and safety calling channel in the maritime mobile service.

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2.1.4 Satellite Service

A number of bands are allocated exclusively to particular services in the satellite service; such bands must also be protected to avoid harmful interference.

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Band Use

406MHz~406.1MHz Earth to space EPIRB transmissions.

1530MHz~1545MHz Maritime mobile service.

Routine communications and also for distress and safety communicatio

ns

(space to earth).

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Band Use

1626.5MHz—1645.5MHz Maritime mobile service.

Routine communications and also

for distress and safety communications

(earth to space).

1645.5MHz—1646.5MHz Earth to space distress/safety communications (IMAR

SAT EPIRB)

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2.1.5 Survival craft stations Equipment for radiotelephony use

in Survival craft stations shall, if capable of operating on any frequency in the bands between 156 MHz and 174 MHz, be able to transmit and receive on 156.8 MHz and at least one other frequency in these bands.

Equipment for transmitting locating signals from survival craft stations shall be capable of operating in the 9200-9500 MHz band.

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Equipment with DSC facilities for use in survival craft shall, if capable of operating:

a) in the bands between 1605 kHz and 2850 kHz, be able to transmit on 2187.5 kHz; (MF)

b) in the bands between 4000 kHz and 27500kHz, be able to transmit on 8414.5 kHz; (HF)

c) in the bands between 156 MHz and 174 MHz, be able to transmit on 156.525 MHz. (VHF)

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2.1.6 Protection of Distress frequencies

It is imperative that distress and safety communications maintain the best possible integrity and the distress and safety frequencies are protected from harmful interference, harmful interference being interference which puts at risk the operation of safety services or radio navigation services or seriously degrades, obstructs, or repeatedly interrupts any radio communication services.

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Therefore to protect distress integrity and to prevent harmful interference, it is absolutely forbidden to broadcast or cause harmful interference by any emissions on any frequency especially those allocated to distress working.

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To further protect distress and safety communications, all other transmissions within particular bands are forbidden, apart from transmissions on specific frequencies. For example in the band 2173.5kHz~2190.5kHz, transmissions are permitted on 2182 kHz, 2174.5 kHz, 2177kHz, 2187.5kHz and 2189.5kHz. All other transmissions in this band are prohibited.

All emissions in the frequency band 156.7625 MHz~156.8375MHz are forbidden which might cause interference to VHF Channel 16 (156.8 MHz).

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2.1.7 Transmitter Tests Test transmissions should only be made when

absolutely necessary and be kept to a minimum to avoid harmful interference especially on the distress and safety frequencies. Whenever practicable , artificial aerials should be used but where aerials do have to be used tests should be conducted on low power and coordinated with competent authorities.

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Testing on distress and safety calling frequencies should be avoided. Testing stations must always identify themselves and make it clear they are sending a test transmission. Before making a test operators should listen on the frequency to be used to ensure that no distress or safety communications are in progress.

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2.1.8 GMDSS Watchkeeping Arrangements Coast stations

Those coast stations assuming a watch-keeping responsibility in the GMDSS shall maintain an automatic DSC watch on frequencies and for periods of time as indicated in the information published in the List of Coast Stations.

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Coast earth stations (satellite communication)

Those coast earth stations assuming a watch-keeping responsibility in the GMDSS shall maintain a continuous automatic watch for appropriate distress alerts relayed by space stations.

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Ship stations Ship stations, where so equipped,

shall, while at sea, maintain an automatic DSC watch on the appropriate distress and safety calling frequencies in the frequency bands in which they are operating. Ship stations, where so equipped, shall also maintain watch on the appropriate frequencies for the automatic reception of transmissions of meteorological and navigational warnings and other urgent information to ships. However, ship stations shall also continue to apply the appropriate watch-keeping provisions of the appropriate Radio Regulations, (see Resolution 331 (Rev.WRC-97)).

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Listening watches on 2182 kHz are no longer mandatory.

In 1998, the Maritime Safety Committee of the International Maritime Organization resolved that, from the coming into force of the GMDSS, until 1st February 2005 every ship while at sea shall maintain, when practicable, a continuous listening watch on VHF Ch 16; such a watch shall be kept at the position from which the ship is normally navigated.

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Ship stations complying with the provisions of the Radio Regulations should, where practicable, maintain a watch on the frequency 156.650 MHz (VHF Ch 13) for communications related to the safety of navigation.

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Ship earth stations (satellite communication) Ship earth stations complying with the

provisions of the Radio Regulations shall, while at sea, maintain watch except when communicating on a working channel.

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2. 1. 9 Watchkeeping: Alert Calls

Some HF coast stations offer a watch facility on the HF DSC safety frequencies for GMDSS sea areas A3 and A4.

As per Regulation 12 of Chapter IV of the Amendments to the 1974 SOLAS Convention (concerning radio communications for GMDSS), every ship, while at sea, shall maintain a continuous watch:

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(a) on DSC Channel 70 VHF, if the ship, in accordance with the requirements of regulation 7.1.2 (of the amendments to the 1974 SOLAS Convention), is fitted with a VHF radio installation;

(b) on the distress and safety DSC frequency of 2187.5 kHz, if the ship, in accordance with the requirements of regulation 9.1.2 or 10.1.3 (of the amendments to the 1974 SOLAS Convention), is fitted with an MF radio installation;

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  (c) on the distress and safety DSC frequencies of

2187.5 kHz and 8414.5 kHz and at least one of the other HF DSC frequencies (4207.5 kHz, 6312 kHz, 12577 kHz or 16804.5 kHz), the frequency chosen will be appropriate to the ship's position and time of day, if the ship, in accordance with the requirements of regulation 10.2.2 or 11.1 (of the amendments to the 1974 SOLAS Convention), is fitted with an MF/HF radio installation. This watch may be kept by means of a scanning receiver;

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2.1. 10 Dedicated DSC Watchkeeping Receiver

This is a scanning type of receiver which sequentially switches between 2187.5kHz and 8414.5kHz. The receiver is able to detect a special "dot pattern" at a particular speed (100 baud) which is sent at the beginning of every DSC call. Should a distress alert be intercepted on any band the call will be processed and an audible alarm will sound. When the receiver is connected to an associated DSC controller the incoming call will be displayed.

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Some types of equipment may have an automatic printer fitted to give a hard copy of any incoming calls. The equipment can be manually programmed to scan any of the other four remaining HF maritime DSC distress and safety calling frequencies as well as the two frequencies mentioned above. It performs this scanning operation within two seconds before repeating the operation.

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2. 2 DISTRESS SERVICES

2. 2. 1 Distress & Safety Operational Procedures

Services available for distress and safety communications are terrestrial radiocommunication in the MF, HF and VHF bands and satellite communication. Distress alerts are transmitted either:

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(a)  via satellite with absolute priority using

the general communication channels; or

(b) via satellite using exclusive distress and

safety frequencies; or

(c) using DSC on the appropriate distress

and safety frequencies in the MF, HF

or VHF bands.

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The authority of the master or person responsible for the ship, aircraft or other vehicle is required before a distress alert can be transmitted.

All stations receiving a DSC distress alert must immediately cease any transmission which may interfere with distress traffic. Stations must continue the watch until the distress alert has been acknowledged.

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2. 2. 2 Distress Alerting A distress alert transmission implies that a mobile

unit (ship, aircraft or other vehicle) or a person is in distress or imminent danger and requires immediate assistance. A distress alert may be defined as:

(a) In the terrestrial radiocommunication bands:

a digital selective call (DSC) using the distress call format; or

(b) In the satellite service:

a message using the distress format for relay

through space stations.

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The distress alert must include the identification of the station in distress and its position. Other information such as the nature of the distress and type of assistance required or anything else which may facilitate rescue may be included in the alert.

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Ship to shore distress alerts are used to warn Rescue Coordination Centres (RCC) that a vessel is in distress. This alerting is routed via LES using satellite transmissions from MES or EPIRB. Alternatively, using the terrestrial service, alerts from ship stations or EPIRBs are made to coast stations. Ship to ship alerts warn other vessels in the vicinity of the distressed vessel of the distress situation using DSC techniques in the MF and VHF terrestrial bands. The HF band may also be used.

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2. 2. 3 Shore to Ship Distress Alert Relay A coast station or an RCC which receives a

distress alert shall initiate the transmission of a shore to ship distress alert relay. This distress alert relay will be addressed to all ships, to selected ships or to an individual ship using the satellite or terrestrial service. Such alert relay messages must contain the identification of the mobile unit in distress, its position and any additional information which facilitates rescue operations.

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2. 2. 4 Distress Alert by a Station not Itself in Distress

Where a station in the mobile or mobile satellite service learns another mobile unit is in distress it must transmit a distress alert when:

(a)  the mobile unit in distress is not in a position to transmit the distress alert itself; or

(b) the master or person responsible for the mobile not in distress or the person responsible for the land station considers further help is required.

A station transmitting a distress alert relay must make it very clear that it is not itself in distress.

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2. 2. 5 Acknowledgement of Receipt of Distress Alerts Satellite service

Acknowledgement of receipt of an alert from a MES must be sent immediately.

Terrestrial service

Acknowledgement of receipt of a distress alert by DSC on terrestrial bands must be in accordance with relevant recommendations.

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Coastal radio/earth station

Public communications network

RCC

Ship in distress

Ship in vicinity

Distress alert

Dis

tress

ale

rt

Distress alert relay

Distress alert by a station not itself in distress

acknowledgement

ackn

owle

dgem

ent

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Radiotelephony Acknowledgements from a ship or MES are given after the

distress message has been received and must take the standard RT form:

• the distress signal MAYDAY; • the call sign or other identification of the station sending

the distress message, spoken three times;

• the words THIS IS (or DE spoken as DELTA ECHO in the case of language difficulties) ;

• the call sign or other identification of the station acknowledging receipt, spoken three times;

• the word RECEIVED (or RRR spoken as ROMEO ROMEO ROME in the case of language difficulties) ;

• the distress signal MAYDAY.

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Example:

MAYDAY NONSUCH NONSUCH NONSUCH

THIS IS

SEASTAR SEASTAR SEASTAR

RECEIVED MAYDAY

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RadiotelexAcknowledgements must be given in the form:

• the distress signal MAYDAY; • the call sign or other identification of the station sending t

he distress alert;

• the word DE (meaning "this is" or "from"); •the call sign or other identification of the station acknowled

ging receipt of the distress alert;

• the signal RRR; • the distress signal MAYDAY.

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Example :

MAYDAY BXXX

DE

BAAA

RRR MAYDAY

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Acknowledging receipt of the distress alert from an MES using directing telegraphy is given by a LES receiving the alert by re-transmitting the ship station identity of the MES sending the alert.

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2. 2. 6 Acknowledging Receipt of Distress Alerts by

Coast Stations, LESs or RCCs Coast stations or a land earth stations, on reception of

the initial distress alert must forward the alert to the appropriate RCC as soon as possible.

The alert must be acknowledged as soon as possible by a coast station or RCC via a coast station or appropriate LES.

Methods: Coast station: DSC LES: RT or telex

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Where a coast station uses DSC to acknowledge a distress alert, the acknowledgement must be made on the same distress calling frequency used for the original alert and be addressed to all ships. Details of the identity of the ship in distress must be included in the acknowledgement message.

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2. 2. 7 Acknowledging Receipt of Distress Alerts by S

hip Stations

A ship receiving a distress alert must inform the master or person responsible for the ship of the contents of the alert as soon as possible.

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In those areas where reliable communications with a coast station is possible, ships should delay acknowledgement for a short period to permit coast stations to acknowledge first.

Ships may be trading in areas where reliable communication with a coast station is not practicable. In these circumstances if they receive a distress alert from a ship station, which is beyond doubt, in their vicinity, they must acknowledge receipt as soon as possible. They must also, if so equipped, inform a RCC of the alert via a coast station or LES.

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Ships receiving a HF distress alert do not acknowledge it but should set watch on the RT frequency indicated in the distress alert, they may also set watch on the telex (NBDP) frequency associated with the distress alert frequency. If however the alert is not acknowledged by a coast station within three minutes then the receiving ship station must relay the distress alert.

Ships acknowledging receipt of a distress alert under the circumstances outlined above should:

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(a)  acknowledge receipt of the alert using RT on

the distress and safety frequency on the band

used for the alert; or

(b) acknowledge the alert using DSC on the appropriate frequency, if acknowledgment by RT of an alert received on the MF or VHF distress alerting frequency is unsuccessful.

Ships which have received a shore to ship distress alert should establish communication as directed by the shore station and render assistance as required.

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2. 2. 8 Preparations for Handling Distress Traffic

On receipt of a transmitted DSC distress alert, ship and coast stations must set a watch on the radiotelephone distress and safety frequency associated with the frequency on which the distress alert was received.

Distress alert # distress traffic

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For example, if the DSC distress alert was transmitted on 6312 kHz then a listening watch must be set on the RT distress frequency of 6215 kHz.

Similarly ship and coast stations with NBDP equipment must set watch in the NBDP distress frequency if the distress alert message indicates that NBDP is to be used for subsequent communications. If practicable, stations should set watch on the appropriate RT frequency associated with the distress alert frequency.

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2. 2. 9 Distress Traffic

The distress traffic is defined as all messages relating to the immediate assistance required by the ship in distress. It also includes search and rescue (SAR) communications and on-scene communications. All distress traffic should take place as far as possible on the frequencies set aside in band for this purpose. (distress, urgency and safety frequencies or channels)

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When using radiotelex for distress traffic, error correction techniques must be used. All messages must be preceded by at least one carriage return, a line feed signal, a letter shift signal and the distress signal MAYDAY. Distress communication should be established by the ship in distress and should be made in the broadcast forward error correction mode (FEC). ARQ (automatic repetition request) mode may subsequently be used where it is advantageous to do so.

When using radiotelephony for distress traffic, simplex mode is recommend. The purpose is to allow other parties participating in SAR listen to the distress traffic.

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2. 2. 10 Imposing Silence The RCC responsible for

controlling SAR operations also coordinates the distress traffic relating to the incident, it may however appoint another station to do this. Controlling stations may impose silence on stations which interfere with distress or SAR traffic; this may be addressed to all stations or to an individual station. The procedure used is :

Shut up!!!

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(a) in radiotelephony, the signal

SEELONCE MAYDAY, pronounced

as in the French expression

"silence, m'aider";

(b) in NBDP telex normally using FEC

mode the signal SILENCE MAYDAY.

However the ARQ mode may be used

when it is advantageous to do so.

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All stations, which are aware of distress traffic but are not taking part in, forbidden to transmit on the frequencies being used for distress until they receive a signal indicating normal working may be resumed.

A station in the mobile service which is able to continue its normal while following distress traffic may do so. This is when the distress is well established and provided the mobile station does not interfere with distress traffic as previously indicated.

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2.2.11 Resumption of Normal Working

When distress traffic has ceased on frequencies which have been used for distress traffic, the RCC or station controlling SAR operations must initiate a message for transmission on those frequencies indicating the distress traffic has finished.

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On radiotelephony this message consists of: •  the distress signal MAYDAY;

•  the call 'Hello all stations' or CQ (spoken as CHARLIE QUEBEC spoken three times) ;

• the words THIS IS (or DE spoken as DELTA ECHO in the case language difficulties) ;

• the call sign or other identification of the station sending the message;

• the time of handing in the message;

• the name and call sign of the mobile station which was in distress;

• the words SEELONCE FEENEE pronounced as the French word

"silence fini".

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Example

MAYDAY

HELLO ALL STATIONS, ALL STATIONS, ALL STATIONS

THIS IS

SEASTAR SEASTAR SEASTAR,

0920

NONSUCH/BXXX

SEELONCE FEENEE

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When using radiotelex, the message consists of:

• the distress signal MAYDAY;

•   the call CQ;

•   the word DE;

• the call sign or other identification of the station sending the message;

• the time of handing in the message;

• the name and call sign of the mobile station which was in distress;

• the words SILENCE FINI.

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Example:

MAYDAY CQ DE BAAA 0920 NONSUCH/BXXX SILENCE FINI

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2. 2. 12 On-scene communications

On-scene communications are those between the mobile unit in distress and assisting mobile units, and between the mobile units and the unit

coordinating search and rescue operations. Control of on-scene communications is the

responsibility of the unit coordinating search and rescue operations. Simplex communications shall be used so that all on-scene mobile stations may share relevant information concerning the distress incident. If direct-printing telegraphy is used, it shall be in the forward error-correcting mode.

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The preferred frequencies in radiotelephony for on-scene communications are 156.8MHz and 2182kHz. The frequency 2174.5kHz may also be used for ship-to-ship on-scene communications using, narrow-band direct-printing telegraphy in the forward error correcting mode.

In addition to 156.8MHz and 2182kHz. the frequencies 3023kHz, 4125 kHz, 5680kHz, 123.1 MHz and 156.3MHz may be used for ship-to-aircraft on-scene communications.

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The selection or designation of on-scene frequencies is the responsibility of the unit coordinating search and rescue operations.

Normally, once an on-scene frequency is established, a continuous aural or teleprinter watch is maintained by all participating on-scene mobile units on the selected frequency.

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2.2.13 Locating and homing signals

Locating signals are radio transmissions intended to facilitate the finding of a mobile unit in distress or the location of survivors. These signals include those transmitted by searching units, and those transmitted by the mobile unit in distress, by survival craft, by float-free EPIRBS, by satellite EPIRBs and by search and rescue radar transponders (SART) to assist the searching units.

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Homing signals are those locating signals which are transmitted by mobile units in distress, or by survival craft, for the purpose of providing searching units with a signal that can be used to determine the bearing to the transmitting stations.

Locating signals may be transmitted in the following frequency bands:

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156-174 MHz: VHF EPIRB (70CH) 406-406.1 MHz: COSPAS-SARSAT EPIRB 1645.5-1646.5 MHz: INMARSAT EPIRB and 9200-9500 MHz: 9GHz Radar and SART.

Locating signals shall be in accordance with the relevant ITU-R Recommendations

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2. 2. 14 Search and Rescue Transponders (SARTs)

In GMDSS, SARTs are mandatory requirements and are used as homing devices to assist rescue craft locate the position of the distress incident.

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2. 2. 15 Charging for Distress Communication

The INMARSAT council defined what constituted distress and safety calls, and confirmed that calls conforming to these definitions would not be charged for the use of satellites. This took effect from 1 January 1992, a month before GMDSS was introduced. The definition of ship to shore distress and safety traffic is:

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(a) distress alerts; (b) SAR coordination communications including communication subsequent to the initial distress alerts, by voice or telex, relating to the immediate assistance required by a ship which is in distress and in grave and imminent danger, provided that they are made to associated rescue coordination centres via code 39; (c) urgent navigational/meteorological danger

reports by telecommunications via code 42;

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(d) medical assistance for grave and

imminent danger, by voice or telex via

code 38 to an agency recognised by

national maritime administrations.

  Equivalent waiver arrangements cover ship to shore

traffic. It was also agreed that reduced charges will apply for ship to shore medical advice communications via code 32,

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2.2.16 Distress Communications by DSC

I. By ship station

2.2.16.1 Transmission of DSC Distress Alert

A distress alert should be transmitted if, in the opinion of the Master, the ship or a person or persons on it is in distress and requires immediate assistance.

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A DSC distress alert should as far as possible include the ship's last known position and the time (in UTC: Universal Time Coordinated) when it was valid. The position and the time may be included automatically by the ship's navigational equipment or may be inserted manually. The DSC distress alert is transmitted as follows:

* Tune the transmitter to the DSC distress channel (2187.5kHz on MF, Channel 70 on VHF)

* If time permits, key in or select on the DSC equipment keyboard: - the nature of distress; - the ship's last known position (latitude and longitude); - the time (in UTC) the position was valid; - type of subsequent distress communication (telephony); in accordance with the DSC equipment manufacturer's instructions. * Transmit the DSC distress alert. * Prepare for the subsequent distress traffic by tuning the transmitter and the

radiotelephony receiver to the distress traffic channel in the same band, i.e. 2182 kHz on MF, Channel 16 on VHF, while waiting for the DSC distress acknowledgement.

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Coastal radio/earth station

Public communications network

RCC

Ship in distress

Ship in vicinity

Distress alert

Dis

tress

ale

rt

Distress alert relay

Distress alert by a station not itself in distress

acknowledgement

ackn

owle

dgem

ent

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2.2.16.2 Actions on receipt of a Distress Alert

Ships receiving a DSC distress alert from another ship should normally not acknowledge the alert by DSC since acknowledgement of a DSC distress alert by use of DSC is normally made by coast stations only.

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Only if no other station seems to have received the DSC distress alert, and the transmission of the DSC distress alert continues, the ship should acknowledge the DSC distress alert by use of DSC to terminate the call. The ship should then, in addition, inform a coast station or a Coast Earth Station by any practicable means. (MF and VHF)

HF: relay instead of acknowledgement in the above circumstance.

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Ships receiving a DSC distress alert from another ship should also defer the acknowledgement of the distress alert by radiotelephony for a short interval, if the ship is within an area covered by one or more coast stations, in order to give the coast station time to acknowledge the DSC distress alert first.

A ship receiving a DSC distress alert from another ship shall:

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* Watch for the reception of a distress acknowledgement on the distress channel (2187.5kHz on MF, Channel 70 on VHF);

from coastal radio station

* Prepare for receiving the subsequent distress communication by tuning the radiotelephony receiver to the distress traffic frequency in the same band in which the DSC distress alert was received, i.e. 2182 kHz on MF, channel 16 on VHF;

Acknowledge the receipt of the distress alert by transmitting the following, by radiotelephony on the distress traffic frequency in the same band in which the DSC distress alert was received, i.e. 2182 kHz on MF, Channel 16 on VHF:

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- "MAYDAY"; - the 9-digit identity of the ship in distress, repeated

3 times; - "this is"; - the 9-digit identity or the call sign or other identifi

cation of own ship, repeated 3 times; - "RECEIVED MAYDAY".

Ships out of range of a distress event or not able to assist should only acknowledge if no other station appears to acknowledge the receipt of the DSC distress alert.

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2.2.16.3 Distress Traffic On receipt of a DSC distress acknowledgement, the ship in distress

should commence the distress traffic by radiotelephony on the distress traffic frequency (2182 kHz on MF, Channel 16 on VHF) as follows:

- "MAYDAY"; - "this is"; - the 9-digit identity and the call sign or other identification of the

ship; - the ship's position in latitude and longitude or other reference to a

known geographical location; - the nature of distress and assistance wanted; - any other information which might facilitate the rescue.

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2.2.16.4 Transmission of a DSC Distress Relay Alert

A ship knowing that another ship is in distress shall transmit a DSC distress relay alert if:

- the ship in distress is not itself able to transmit the distress alert;

- the master of the ship considers that further help is

necessary.

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Coastal radio/earth station

Public communications network

RCC

Ship in distress

Ship in vicinity

Distress alert

Dis

tress

ale

rt

Distress alert relay

Distress alert by a station not itself in distress

acknowledgement

ackn

owle

dgem

ent

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The DSC distress relay alert is transmitted as follows:

* Tune the transmitter to the DSC distress channel (2187.5 kHz on MF, Channel 70 on VHF);

* Select the distress relay call format on the DSC equipment;

* Key in or select on the DSC equipment keyboard:

- all Stations Call or the 9-digit identity of the appropriate coast station;

- the 9-digit identity, of the ship in distress, if known;

- the nature of distress;

- the latest position of the ship in distress, if known;

- the time (in UTC) the position was valid (if known);

- type of subsequent distress communication (telephony);

- transmit the DSC distress relay call.

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2.2.16.5 Acknowledgement of a DSC Distress Relay Alert

received from a Coast Station

Coast stations, after having received and acknowledged a DSC distress alert, may if necessary, re-transmit the information received as a DSC distress relay call, addressed to all ships, all ships in a specific geographical area, a group of ships or a specific ship.

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Ships receiving a distress relay call transmitted by a coast station shall not use DSC to acknowledge the call, but should acknowledge the receipt of the call by radiotelephony on the distress traffic channel in the same band in which the relay call was received, i.e. 2182 kHz on MF, Channel 16 on VHF.

Acknowledge the receipt of the distress alert by transmitting the following, by radiotelephony on the distress traffic frequency in the same band in which the DSC distress relay alert was received:

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- "MAYDAY"; - the 9-digit identity or the call sign or other

identification of the calling coast station; - ''this is"; - the 9-digit identity or call sign or other identification

of own ship; - "RECEIVED MAYDAY".

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2.2.16.6 Acknowledgement of a DSC Distress Relay Alert

received from another Ship Ships receiving a distress relay alert from another

ship shall follow the same procedure as for acknowledgement of a distress alert, i.e. the procedure given in section 2.2.16.2 above.

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2.2.16.7 Cancellation of an inadvertent Distress Alert (Distress Call) A station transmitting an inadvertent distress alert shall cancel the distress alert using the following

procedure:

- Immediately transmit a DSC "distress cancellation" with own ship's MMSI inserted as identification of ship in distress. In addition cancel the distress alert aurally over the telephony distress traffic channel associated with each DSC channel on which the "distress call" was transmitted.

- Monitor the telephony distress traffic channel associated with the DSC channel on which the distress was transmitted, and respond to any communications concerning that distress alert as appropriate.

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II. BY COAST STATION

2.2.16.8 Reception of a DSC Distress Alert (Distress Call) The transmission of a distress alert indicates that a

mobile unit (a ship, aircraft or other vehicle ) or a person is in distress and requires immediate assistance. The distress alert may be a digital selective call using a distress call format (distress call).

Coast stations in receipt of a distress call shall ensure that it is routed as soon as possible to an RCC. The receipt of a distress call is to be acknowledged as soon as possible by the appropriate coast station.

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2.2.16.9 Acknowledgement of a DSC Distress Alert (Distress call) The coast station shall transmit the

acknowledgement on the distress calling frequency on which the call was received and should address it to all ships. The acknowledgement shall include the identification of the ship whose distress call is being acknowledged.

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The acknowledgement of a DSC distress call is transmitted as follows:

* Use a transmitter which is tuned to the frequency on which the distress call was received.

* In accordance with the DSC equipment manufacturer's instructions, key in or select on the DSC equipment keyboard:

- distress call acknowledgement;

- 9-digit identity of the ship in distress;

- nature of distress;

- distress coordinates;

- the time (in UTC) when the position was valid.

* Transmit the acknowledgement

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2.2.16.10 Transmission of a DSC Distress Relay Alert (Distress Relay call) Coast stations shall initiate and transmit a distress relay call in any

of the following cases: a) when the distress of the mobile unit has been notified to the

coast station by other means and a broadcast alert to shipping is required by the RCC; and

b) when the person responsible for the coast station considers that further help is necessary (Close cooperation with the appropriate RCC is recommended under such conditions).

In the cases mentioned above, the coast station shall transmit a shore-to-ship distress relay call addressed, as appropriate, to all ships, to a selected group of ships, to a geographical area or to a specific ship.

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The distress relay call shall contain the identification of the mobile unit in distress, its position and other information which might facilitate rescue.

The distress relay call is transmitted as follows:

* Use a transmitter which is tuned to the frequency for DSC distress calls (2187.5 kHz on MF, 156.525 MHz/Channel 70 on VHF).

* In accordance with the DSC equipment manufacturer's instructions, key in or select on the DSC equipment keyboard.

- distress relay call;

- the format specifier (all ships, group of ships, geographical area or individual station);

- if appropriate, the address of the ship, group of ships or geographical area (not required if the format specifier is "all ships");

- 9-digit identity of the ship in distress, if known

- nature of distress;

- distress coordinates;

- time (in UTC) when the position was valid.

* Transmit the distress relay call.

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2.2.16.11 Reception of a Distress Relay Alert (Distress Relay Call)

If the distress relay call is received from a ship station, coast stations on receipt of the distress relay call shall ensure that the call is routed as soon as possible to an RCC.

The receipt of the distress relay call is to be acknowledged as soon as possible by the appropriate coast station using a DSC distress relay acknowledgement addressed to the ship station. If the distress relay call is received from a coast station, other coast stations will normally not have to take further action.

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2. 2. 17 Satcom Distress Procedure The following procedures are general procedures

using INMARSAT-A; for specific equipment refer to manufacturer's instructions. Similarly for INMARSAT-C (telex only), the procedures are of a general nature and again users should refer to manufacturer's instructions. Telex communication is the preferred mode of operation since it provides a written record of distress traffic. There are four levels of priority:

0         - Routine traffic

1         - Safely traffic

2         - Urgency traffic

3         - Distress traffic

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2. 2. 17. 1 By telephone (1)  Lift off the handset.

(2) Remove protective cover and select EMERGENCY (priority 3).

(3) Dial correct digits to select required LES

(usually the one nearest to ship). 01 Southbury 01 Santa Paula 02 Goonhilly 03 Yamaguchi 04 Eik

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  (4)  After making contact with RCC:

(5)  Begin message:

MAYDAY MAYDAY MAYDAY followed by name or other identification of the ship in distress; particulars of position; the nature of the distress and the kind of assistance required; any other information which might facilitate the rescue.

(6) Before reverting to routine traffic ensure priority 0 is restored.

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2.2.17.2 By telex (1)  Switch telex on-line. (2)  Remove protective cover and select EMERGENCY (priority 3). (3)  Type correct digits followed by + to select LES

01 Southbury

01 Santa Paula

02 Goonhilly

03 Yamaguchi

04 Eik

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(4) Upon receipt of answerback from RCC:

(5)  Type the following:

SOS SOS SOS followed by

name or other identification of the ship in distress; particulars of its position; the nature of the distress and the kind of assistance required; any other information which might facilitate the rescue.

(6) Before reverting to routine traffic ensure priority 0 is restored.

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2.2.17.3 Sending distress alerts on an Inmarsat-C terminal

There are two methods of sending distress alerts:

(1) by keying the information into the MES terminal using the edit facilities; or

(2)  by using the remote distress alert button (s).

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2.2.17.4 Using the edit facilities on the MES terminal This is the preferred method as it enables the operator to key in up-to-date

information. Method

(1) Select the distress alert menus according to the manufacturer's operating instructions.

(2) when requested, complete following message:

MES ID - entered automatically by MES.

LES required - select nearest LES within the ocean region to own ship's position.

Position - latitude and longitude entered manually via keyboard, or automatically from electronic navigator such as GPS.

Date & time of last - enter time manually or automatically from position update electronic navigator (all times to be quoted in UTC).

Position status should read satisfactorily.

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Nature of distress - One of the following:

Unspecified Listing

Fire/explosion Sinking

Flooding Disabled and adrift

Collision Abandoning ship

Grounding Assistance required

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Ship's course(00~3590) - Entered manually or automatically from gyro compass.

Ship's speed (Knots) - Entered manually or automatically from speed log.

(3) Press the appropriate key(s) to send the alert.

(4) If an acknowledgement is not received from both the LES and RCC, within five minutes repeat the distress alert.

INMARSAT INMARSAT CC

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2. 2. 17. 5 Using the remote distress button(s) on the MES If distress alert buttons are fitted to the MES and there is

insufficient time to use the MES key board, an alert may be initiated in this manner. However, the information stored may be out of date unless recently updated positional information has been inserted, or it is continuously updated by an electronic navigator.

In the interests of safety of life at sea, operators are advised to keep the MES logged on with up to date positional information in the store at all times.

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Method (1) Press the remote distress alert button until an indication

that the MES is in the distress alert mode. This condition should remain until an acknowledgement is received from the LES and then the nearest RCC.

(2) If no acknowledgement is received from both the LES and RCC, within five minutes repeat the distress alert.

(3) It possible send updated information about your distress situation using the same format.

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2. 2. 18 GMDSS Distress Alert Procedure

It is apparent that mobile stations in distress have a number of options available to them to alert shore-based authorities (or other ships) that they require assistance.

The communication medium used will, to a large extent, depend on the area the vessel is in and on the propagation conditions at the time. For example:

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• Ships in Al areas would transmit a ship/shore and ship/ship alert on Channel 70 VHF using DSC.

• Ships in A2 areas would transmit their ship/shore and ship/ship alert on 2187.5kHz using DSC and indicating whether RT or telex (NBDP) is to be used to transmit the distress message, 70CH for ship/ship distress alert.

For ships in areas A3 and A4 ship to ship alerts must be transmitted on 2187.5 kHz using DSC and 70CH using DSC.

However for ship to shore alerts a choice is available once again depending on:

(i)  the equipment fitted; (ii) this equipment's operational availability;

(iii) the existing propagation conditions. For example: (a)  An INMARSAT'S Land Earth Station could be alerted. (b) A coast station could be alerted by using HF RT communications wit

h DSC. (c)  A satellite EPIRB could be activated.

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Such arrangements are designed to offer a high probability of a successful alert irrespective of the sea area involved, thus enabling a rapid response to the alert by rescue team. It should be noted that ships in all areas are required to be fitted with EPIRBs under GMDSS carriage requirements. Thus in the event of abandoning ship without sending a distress alert the EPIRB provides a secondary method of distress alerting.

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Any alert (Non-EPIRB) should contain the following information:

(a)  ship's identification; (b)  its position; (c)  the nature of the distress; (d) information which can assist rescuers locate the

distress ship and assist in its rescue.

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When alerts are received by one of INMARSAT's Land Earth Stations they are then passed to a Rescue Coordination Centre (RCC). The RCC will relay the alert to search and rescue units and to other ships in the area and will control and coordinate rescue procedures. Relaying of alerts to other vessels in the area is carried out using satellite communications or by terrestrial communications on appropriate frequencies.

Use is made of " area call" facilities to notify only those ships in the immediate vicinity of the distress. Ships which have been alerted in this way then establish communications with the RCC via an appropriate medium (satellite or terrestrial communications).

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2. 2. 19 False Alerts False alerts caused by the inadvertent of incorrect operati

on of GMDSS equipment can put a significant burden on Search and Rescue Centres. The chances of false alerts coinciding with a real life distress situation are very real and as a consequence, search and rescue forces could be delayed in responding to a real distress.

Most false alerts are caused as a result of human error.

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2. 3 URGENCY SERVICES

Urgency and safety communications are defined as those relating to: (a) navigational and meteorological warnings and urgent information; (b) ship to ship safety of navigation communications; (c) ship reporting communications; (d) support communications for SAR operations; (e) other urgency or safety messages; (f) communications relating to the navigation, movements and needs

of ships and weather observation messages destined for an official meteorological service.

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2. 3.1 Urgency Communications The use of the urgency call format implies that the station makin

g the call has a very urgent message to transmit concerning the safety of the mobile unit or a person. The urgency signal or urgency call format must only be sent on the authority of the master or person responsible for the mobile unit or by a land earth station or coast station with approval of the responsible authority. The urgency signal and message must be transmitted on one or more of the authorised distress and safety frequencies or the maritime mobile satellite service.

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In the terrestrial service, the announcement of the urgency message must be made on one or more of the authorised distress and calling frequencies using DSC and the urgency call format. If the maritime mobile telex service is to be used, a separate urgency announcement is not required, as selection of URGENT PRIORITY gains priority access to the system.

The urgency signal in radiotelephony consists of the words PAN PAN, each word being pronounced as in the French word "panne" , In radiotelephony the urgency message must be preceded by the urgency signal repeated three times together with the identification of the transmitting station.

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Example:

PAN PAN, PAN PAN, PAN PAN ALL STATIONS, ALL STATIONS, ALL STATIONS THIS IS SEASTAR SEASTAR SEASTAR

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In NBDP (telex) the urgency message must be preceded by the urgency signal and the identification of the transmitting station.

Example:

PAN PAN DE BACD

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Urgency communication using NBDP telex should be established in the broadcast FEC mode. ARQ mode may subsequently be used where it is advantageous to do so.

All messages must be preceded by at least one carriage return (CR), a line feed signal (LF), and the urgency signal (PAN PAN).

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2.3.2 Urgency Messages and DSC

I. BY SHIP STATIONS 2.3.2.1 Transmission of Urgency Messages Transmission of urgency messages shall be carried out in two steps:

* Announcement of the urgency message,

* Transmission of the urgency message.

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The announcement is carried out by transmission of a DSC urgency call on the DSC distress calling channel (2187.5 kHz on MF, Channel 70 on VHF).

The urgency message is transmitted on the distress traffic channel(2182 kHz on MF, Channel 16 on VHF).

The DSC urgency call may be addressed to all stations or to a specific station. The frequency on which the urgency message will be transmitted shall be included in the DSC urgency call.

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The transmission of an urgency message is thus carried out as follows: Announcement:

* Tune the transmitter to the DSC distress calling channel (2187.5 kHz on MF, Channel 70 on VHF);

* Key in or select on the DSC equipment keyboard:

- All Ships Call or the 9-digit identity of the specific station;

- the category of the call (urgency):

- the frequency or channel on which the urgency message will be transmitted;

- the type of communication in which the urgency message will be given (radiotelephony);

in accordance with the DSC equipment manufacturer's instructions.

* Transmit the DSC urgency call.

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Transmission of the urgency message: * Tune the transmitter to the frequency or channel indicated in the

DSC urgency call; * Transmit the urgent message as follows: - "PAN PAN", repeated 3 times; - "ALL STATIONS" or called station, repeated 3 times; - "this is"; - the 9-digit identity and the call sign or other identification of

own ship; - the text of the urgency message.

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2.3.2.2 Reception of an Urgency Message

Ships receiving a DSC urgency call announcing an urgency message addressed to all ships shall NOT acknowledge the receipt of the DSC call, but should tune the radiotelephony receiver to the frequency indicated in the call and listen to the urgency message.

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II. BY COAST STATIONS

2.3.2.3 Transmission of a DSC Announcement by coast stations

The announcement of the urgency message shall be made on one or more of the distress and safety calling frequencies using DSC and

the urgency call format. The DSC urgency call may be addressed to all ships, to a selected

group of ships, to a geographical area or to a specific ship. The frequency on which the urgency message will be transmitted after the announcement shall be included in the DSC urgency call.

The DSC urgency call is transmitted as follows:

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* Use a transmitter which is tuned to the frequency for DSC distress calls (2187.5 kHz on MF, 156.525 MHz /Channel 70 on VHF).

* In accordance with the DSC equipment manufacturer's instructions, key in or select on the DSC equipment keyboard:

- the format specifier (all ships call, group of ships, geographical area or individual station);

- if appropriate, the address of the ship, group of ships or geographical area (not required if the format specifier is "all ships");

- the category of the call (urgency); - the frequency or channel on which the urgency message will be tr

ansmitted; - the type of communication in which the urgency message will be

transmitted (radiotelephony). * Transmit the DSC urgency call. After the DSC announcement, the urgency message will be transmi

tted on the frequency indicated in the DSC call.

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2. 4 SAFETY SERVICES2. 4.1 Safety Communications The safety call format implies that the station making the call has

an important navigational or meteorological warning to transmit. In the terrestrial service the announcement of the safety message must be made on one or more of the authorised distress and calling frequencies using DSC. If the maritime mobile satellite service is to be used, a separate safety announcement is not required.

The safety signal and message must be transmitted on one or more authorised distress and safety frequencies or via the maritime satellite service. The safety signal in radiotelephony consists of the SECURITE pronounced (SAY-CUREE-TAY) as in French.

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Example: SECURITE, SECURITE, SECURITE ALL STATIONS, ALL STATIONS, ALL STATIONS THIS IS SEASTAR SEASTAR SEASTAR

In NBDP telex, the safety message must be preceded by the safety signal and the identification of the transmitting station.

Example:

SECURITE DE BACD

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Safety communication using NBDP telex should be established in the broadcast (forward error correction) mode. ARQ mode may subsequently be used where it is advantageous to do so. All messages must be precede by at least one carriage return, a line feed signal, a letter shift signal and the safety signal (SECURITE).

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Messages containing information concerning the presence of serious ice, dangerous wrecks, or any other imminent danger to navigation, must be transmitted as soon as possible to other ship s in the vicinity, and to the appropriate authorities at the first point coast with which contact can be established. These transmissions are preceded by the safety signal.

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2. 4. 2 Intership Navigation Safety Communication

Intership navigation safety communications are VHF RT communications between ships for the purpose of contributing to the safe movement of ships, Channel 13 VHF is used.

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2. 4. 3 Safety Messages and DSC by ship station

2.4.3.1 Transmission of safety messages shall be carried out in two steps

* Announcement of the safety message, * Transmission of the safety message.

The announcement is carried out by transmission of a DSC safety call on the DSC distress calling channel (2187.5 kHz on MF, Channel 70 on VHF).

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The safety message is normally transmitted on the distress and safety traffic channel in the same band in which the DSC call was sent. i.e. 2182 kHz on MF, channel 16 on VHF.

The DSC safety call may be addressed to all ships, all ships in a specific geographical area or to a specific station. The frequency on which the safety message will be transmitted shall be included in the DSC call.

The transmission of a safety message is thus carried out as follows:

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Announcement:

* Tune the transmitter to the DSC distress calling channel (2187.5 kHz on MF, Channel 70 on VHF);

* Select the appropriate calling format on the DSC equipment (all ships, area call or individual call);

* Key in or select on the DSC equipment keyboard:

- specific area or 9-digit identity of specific station, if appropriate;

- the category of the call (safety);

- the frequency or channel on which the safety message will be transmitted;

- the type of communication in which the safety message will be given

(radiotelephony);

in accordance with the DSC equipment manufacturer's instructions.

* Transmit the DSC safety call.

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Transmission of the safety message: * Tune the transmitter to the frequency or channel indicated in the DSC

safety call. * Transmit the safety message as follows: - "SECURITE", repeated 3 times; - "ALL STATIONS" or called station, repeated 3 times; - "this is"; - the 9-digit identity and the call sign or other identification of own ship; - the text of the safety message.

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2.4.3.2 Reception of a Safety Message

Ships receiving a DSC safety call announcing a safety message addressed to all ships shall NOT acknowledge the receipt of the DSC safety call, but should tune the radiotelephony receiver to the frequency indicated in the call and listen to the safety message.

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2.4.4 Transmission of a DSC Announcement by Coast stations The announcement of the safety message shall be made on

one or more of the distress and safety calling frequencies using DSC and the safety call format.

The DSC safety call may be addressed to all ships, to a group of ships, to a geographical area or to a specific ship. The frequency on which the safety message will be transmitted after the announcement shall be included in the DSC safety call.

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The DSC safety call is transmitted as follows: * Use a transmitter which is tuned to the frequency for DSC distress calls (21

87.5 kHz on MF, 156.525MHz/Channel 70 on VHF). * In accordance with the DSC equipment manufacturer's instructions, key in

or select on the DSC equipment keyboard : - the format specifier (all ships call, group of ships, geographical area or indi

vidual station); - if appropriate, the address of the ship, group of ships or geographical area

(not required if the format specifier is "all ships"); - the category of the call (safety); - the frequency or channel on which the safety message will be transmitted; - the type of communication in which the safety message will be transmitted

(radiotelephony). * Transmit the DSC safety call.

After the DSC announcement, the safety message will be transmitted on the frequency indicated in the DSC call.

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2.5 SPECIAL CONDITIONS AND PROCEDURES FOR DSC COMMUNICATION ON HF BY SHIP STATION 2.5.1 DISTRESS 2.5.1.1 Transmission of DSC Distress Alert

DSC distress alert should be sent to coast stations – e.g. in A3 and A4 sea areas on HF - and on MF and/or VHF to other ships in the vicinity.

The DSC distress alert should as far as possible include the ship's last known position and the time (in UTC) it was valid. If the position and time is not inserted automatically from the ship's navigational equipment, it should be inserted manually.

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Ship-to-shore Distress Alert

Choice of HF band Propagation characteristics of HF radio waves for the actual

season and time of the day should be taken into account when choosing HF bands for transmission of DSC distress alert.

As a general rule the DSC distress channel in the 8 MHz maritime band (8414.5 kHz) may in many cases be an appropriate first choice.

Transmission of the DSC distress alert in more than one HF band will normally increase the probability of successful reception of the alert by coast stations.

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DSC distress alert may be sent on a number of HF bands in two different ways:

a) either by transmitting the DSC distress alert on one HF band, and waiting a few minutes for receiving acknowledgement by a coast station; if no acknowledgement is received within 3 minutes, the process is repeated by transmitting the DSC distress alert on another appropriate HF band etc;

b) or by transmitting the DSC distress alert at a number of HF bands with no or only very short pauses between the calls, without waiting for acknowledgement between the calls.

It is recommended to follow procedure a) in all cases, where time permits to do so; this will make it easier to choose the appropriate HF band for commencement of the subsequent communication with the coast station on the corresponding distress traffic channel.

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Transmitting the DSC alert

* Tune the transmitter to the chosen HF DSC distress channel (4207.5, 6312, 8414.5, 12577,16804.5 kHz)

* Follow the instructions for keying in or selection of relevant information on the DSC equipment keyboard as described in Section 2.1.16.1

* Transmit the DSC distress alert.

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2.5.1.2 Preparation for the subsequent Distress Traffic After having transmitted the DSC distress alert on appropriate DSC distress channels

(HF, MF and/or VHF), prepare for the subsequent distress traffic by tuning the radiocommunication set(s) (HF, MF and/or VHF as appropriate) to the corresponding distress traffic channel(s).

The distress traffic frequencies are: HF: Telephony 4125kHz 6215kHz 8291kHz 12290kHz 16420kHz Telex 4177.5kHz 6268kHz 8376.5kHz 12520kHz 16695kHz MF: Telephony 2182kHz

Telex 2174.5kHz

VHF: Telephony (only) Channel 16 (156.800MHz)

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2.5.1.3 Distress traffic The procedures described in section 2.2.16.

3 are used when the distress traffic on MF/HF is carried out by radiotelephony.

The following procedures shall be used in cases where the distress traffic on MF/HF is carried out by radiotelex:

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* The Forward Error Correcting (FEC) mode shall be used unless specifically requested to do otherwise.

* All messages shall be preceded by - at least one carriage return - line feed - one letter shift - the distress signal MAYDAY.

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* The ship in distress should commence the distress telex traffic on the appropriate distress telex traffic channel as follows:

- carriage return, line feed, letter shift; - the distress signal "MAYDAY"; - the words "this is"; - the 9-digit identity and call sign or other identification of the ship; - the ship's position if not included in the DSC distress alert; - the nature of distress; - any other information which might facilitate the rescue.

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2.5.1.4 Actions on Reception of a DSC Distress Alert on H

F from another Ship Ships receiving a DSC distress alert on HF from another ship shall not acknowledge the alert, but should: * Watch for reception of a DSC distress acknowledgement from a coast station. * While waiting for reception of a DSC distress acknowledgement from a coast station: Prepare for reception of the subsequent distress communication by tuning the HF radiocommunication set (transmitter and receiver) to the rel

evant distress traffic channel in the same HF band in which the DSC distress alert was received * If no distress traffic is received on the HF channel within 1 to 2 minutes, tune the HF radiocornmunication set to the relevant distress traffi

c channel in another HF band deemed appropriate in the actual case. * If no DSC distress acknowledgement is received from a coast station within 3 minutes, and no distress communication is observed going o

n between a coast station and the ship in distress: - Transmit a DSC distress relay alert; - Inform a Rescue Coordination Centre via appropriate radiocornmunications means.

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2.5.1.6 Acknowledgement of a HF DSC Distress Relay Alert received

from a Coast Station Ships receiving a DSC distress relay alert from a coast station

on HF. addressed to all ships within a specified area, should NOT acknowledge the receipt of the relay alert by DSC. but by radiotelephony on the telephony distress traffic channel in the same band(s) in which the DSC distress relay alert was received.

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2.5.2 URGENCY Transmission of urgency messages on HF

should normally be addressed - either to all ships within a specified

geographical area - or to a specific coast station.

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Announcement of the urgency message is carried out by transmission of a DSC call with category urgency, on the appropriate DSC distress channel.

The transmission of the urgency message itself on HF is carried out by radiotelephony or radiotelex on the appropriate distress traffic channel in the same band in which the DSC announcement was transmitted.

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2.5.2.1 Transmission of DSC Announcement of an Urgency

Message on HF

* Choose the HF band considered to be the most appropriate, taking into account propagation characteristics for HF radio waves at the actual season and time of the day; the 8 MHz band may in many cases be an appropriate first choice;

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* Tune the HF transmitter to the DSC distress channel in the chosen HF band;

* Key in or select call format for either geographical area call or individual call on the DSC equipment, as appropriate;

* In case of area call, key in specification of the relevant geographical area;

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* Follow the instructions for keying in or selection of relevant information on the DSC equipment keyboard as described in section 2.3.2.1, including type of communication in which the urgency message will be transmitted (radiotelephony or radiotelex);

* Transmit the DSC call; * If the DSC call is addressed to a specific coast s

tation, wait for DSC acknowledgement from the coast station. If acknowledgement is not received within a few minutes, repeat the DSC call on another HF frequency deemed appropriate.

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2.5.2.2 Transmission of the Urgency

Message and subsequent Action * Tune the HF transmitter to the distress

traffic channel (telephony or telex) indicated in the DSC announcement;

* If the urgency message is to be transmitted using radiotelephony, follow the procedure described in section 2.3.2.1;

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* If the urgency message is to be transmitted by radiotelex, the following procedure shall be used:

- Use the Forward Error Correcting (FEC) mode unless the message is addressed to a single station whose radiotelex identity number is known; - commence the telex message by: * at least one carriage return, line feed, one

letter shift

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* the urgency signal "PAN PAN" * "this is"; * the 9-digit identity of the ship and the

call sign or other identification of the ship * the text of the urgency message Announcement and transmission of

urgency messages addressed to all HF equipped ships within a specified area may be repeated on a number of HF bands as deemed appropriate in the actual situation.

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2.5.2.3 Reception of an Urgency Message Ships receiving a DSC urgency call announ

cing an urgency message shall NOT acknowledge the receipt of the DSC call, but should tune the radiocommunication receiver to the frequency and communication mode indicated in the DSC call for receiving the message.

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2.5.3 SAFETY The procedures for transmission of DSC safety an

nouncement and for transmission of the safety message are the same as for frequency messages, described in section 2.5.2, except that:

- in the DSC announcement, the category

SAFETY shall be used - in the safety message, the safety signal

"SECURITE" shall be used instead of the

urgency signal "PAN PAN".

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2.5.4 PUBLIC CORRESPONDENCE

ON HF The procedures for DSC communication

for public correspondence on HF are the same as for MF.

Propagation characteristics should be taken into account when making DSC communication on HF.

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International and national HF DSC channels different from those used for DSC for distress and safety purposes are used for DSC for public correspondence.

Ships calling a HF coast station by DSC for public correspondence should preferably use the coast station's national DSC calling channel.

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2.5.5 TESTING THE EQUIPMENT USED FOR DISTRESS AND

SAFETY ON HF The procedure for testing the ship's

equipment used for DSC distress, urgency and safety calls on HF by transmitting DSC test calls on HF DSC distress channels is the same as for testing on the MF DSC distress frequency 2187.5 kHz.

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2.6 SPECIAL CONDITIONS AND PROCEDURES FOR DSC COMMUNICATION ON HF BY COAST STATION

2.6.1 DISTRESS

2.6.1.1 Reception and Acknowledgement of a DSC Distress Alert on HF

Ships in distress may in some cases transmit the DSC distress alert on a number of HF bands with only short intervals between the individual calls.

The coast station shall transmit DSC acknowledgement on all HF DSC distress channels on which the DSC alert was received in order to ensure as far as possible that the acknowledgement is received by the ship in distress and by all ships which received the DSC alert.

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2.6.1.2 Distress Traffic The distress traffic should, as a general

rule, be initiated on the appropriate distress traffic

channel (radiotelephony or narrow band direct printing) in the same band in which the DSC alert was received.

For distress traffic by NBDP the following rules apply:

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- All messages shall be preceded by at least

one carriage return, line feed, one letter

shift and the distress signal MAYDAY; - Forward Error Correcting (FEC)

broadcast mode should normally be used

ARQ mode should be used only when

considered advantageous to do so in the

actual situation and provided that the

radiotelex number of the ship is known.

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2.6.1.3 Transmission of DSC Distress

Relay Alert on HF HF propagation characteristics should be

taken into account when choosing HF band(s) for transmission of DSC distress relay alert. IMO Convention ships equipped with HF DSC for distress and safety purposes are required to keep continuous automatic DSC watch on the DSC distress channel in the 8 MHz band and on at least one of the other HF DSC distress channels.

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In order to avoid creating on board ships uncertainty regarding on which band the subsequent establishment of contact and distress traffic should be initiated, the HF DSC distress relay alert should be transmitted on one HF band at a time and the subsequent communication with responding ships be established before eventually repeating the DSC distress relay alert on another HF band.

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2.6.2 URGENCY

2.6.2.1 Transmission of Urgency Announcement and Message on HF

For urgency messages by NBDP the following apply:

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- The urgency message shall be preceded by at least one carriage return, line feed, one letter shift, the urgency signal PAN PAN and the identification of the coast station; - Forward Error Correcting (FEC) broadcast mode should normally be used. ARQ mode should be used only when cons

idered advantageous to do so in the actual situation and provided that the radiotelex number of the ship is known.

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2.6.3 SAFETY2.6.3.1 Transmission of Safety Announcements and Messages on HF

For safety messages by NBDP the following apply:

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- The safety message shall be preceded by at least one carriage return, line feed, one letter shift, the safety signal SECURITE and the identification of the coast station; - Forward Error Correcting (FEC) broadcast mode should normally be used. ARQ mode should be used only when consi

dered advantageous to do so in the actual situation and provided that the radiotelex number of the ship is known.

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2.6.4 TESTING THE EQUIPMENT USED FOR DISTRESS AND

SAFETY The procedures for ships testing their

equipment used for DSC distress, urgent and safety

calls on HF DSC distress channels and the acknowledgement of the test call by the coast station are the same as for testing on the MF DSC distress frequency 2187.5 kHz.

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2.7 SEARCH AND RESCUE RADAR TRANSPONDER

2.7.1 INTRODUCTION At least one Radar Transponder to be carried on every ship of 300 GRT and

above and two Radar Transponders on ships of 500 GRT and above. Radar Transponders may be carried in Survival Craft and may be incorporated in a VHF DSC EPIRB.

The purpose of a search and rescue transponder (SART) is to indicate the position of persons or vessels in distress. A SART is an easily portable device which should be taken into the lifeboat or life raft when abandoning ship.

After switch on, the SART remains in Standby mode (for up to 96 hours) until activated by a 9 GHz radar emission which then causes the SART to transmit a signal appearing as a straight line of 'blips' on the radar display. When switched on it will transmit signals only when triggered by signals from an external marine or aircraft radar operating in the 9 GHz (3 cm) band, it should respond to interrogation from ships at five nautical miles range.

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An audible alarm or small light is incorporated into the device in order that persons in distress will be aware that a rescue ship or aircraft is within close range. Battery capacity should allow 96 hours of standby operation and the SART should be able to respond to interrogating signals even in heavy swell. When a SART is activated it generates a swept frequency signal which shows up on the rescue craft's radar screen. This is a distinctive line of about 12 equally spaced blips extending outwards from the SART's position along its line of bearing. The total length of this line of blips is eight nautical miles. This assists rescue craft locate and approach the scene of the incident.

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2.7.2 SART Signals at Close Range As a rescue ship nears the SART (usually around one nautical

mile) radar antenna sidelobe transmissions cause the dots on the radar screen to change into concentric arcs. At even closer ranges concentric circles appear, which indicates to rescue vessels that the SART is now at very close range. The SART dotted line can be recovered by reducing the radar receiver gain. The exact location of the SART is just inside the first narrow dot (i. e. the one closest to the radar observer).

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2.7.3 OPERATIONAL AND TECHNICAL CHARACTERISTICS

The SART can be activated manually or automatically when placed into the water so that it will thereafter respond when interrogated.

When activated in a distress situation, a SART responds to radar interrogation by transmitting a swept frequency signal which generates as a line of 12 blip code on a radar screen outward from the SART's position along its line of bearing. Displayed on the Plain Position Indicator (PPI), the spacing between each pair of dots will be 0.6 nautical miles.

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In order to distinguish the SART from other responses, it is preferable to use a radar scale between 6 and 12 n miles, this will assist in differentiating between the SART and other responses. As the search craft approaches to within about 1 n mile of the SART, the blip dots will change into wide arcs, and even become complete circles as the SART is closed and becomes continually triggered.

This is a useful warning to the search craft to slow down! This distinctive and unique radar signal is easily recognized and is therefore much easier to spot than a single echo such as from a radar reflector. Moreover, the fact that the SART is actually a transmitter means that the return pulses can be as strong as echoes received from much larger objects. Any radar bandwidth of less than 5 MHz will attenuate the SART signal slightly, so it is preferable to use a medium bandwidth to ensure optimum detection of the SART. The specific Radar Operating Manual should be consulted about the particular radar parameters and bandwidth selection.

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The SART also provides a visual or audible indication of its correct operation and will also inform survivors when it is interrogated by a radar.

The SART should have sufficient battery capacity to operate in the stand-by condition for 96 hours followed by a minimum 8 hours of transmission while being interrogated by a radar. It should also be able to operate under ambient temperatures of

-20°C to + 55°C.

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A SART built to the latest specifications will have excellent receiver sensitivity, and will detect the high power pulses from a search radar at a much greater range then it's relatively weak return pulses will be detected by the radar. The limiting range is therefore determined by the return path.

Four main factors will affect the range at which a SART will be detected on a ship's radar screen:

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1) THE TYPE OF RADAR USED, AND HOW IT IS OPERATED

Clearly, some radars are better than others. Larger vessels will have higher gain antennas, set higher above sea level. The radar receiver performance is also very important and should be optimised.

2) THE WEATHER CONDITIONS

A flat calm will affect performance due to 'multi-path' propagation - radar pulses being reflected from the surface of the sea.

High waves may result in reception at greater distances, due to occasional elevation of both radar and SART; however, detection will be sporadic, due to masking of the signal in the troughs.

Elimination of sea and rain clutter will depend on the radar used, and the skill of the operator, as for normal radar operations.

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3) THE MOUNTING OF THE SART ON THE SURVIVAL CRAFT

The mounting of the SART is the one factor over which the SART user has some control. For maximum range an unobstructed mounting as high as possible is required.

The IMO Recommended Performance Standard for the SART calls for a range of "up to at least 5 nautical miles", for a SART mounted 1 m above sea level. This assumes a search radar complying with IMO requirements, with its antenna 15m above sea level. Tests have shown the importance of maintaining the SART antenna height of at least 1 m above sea level;

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the following results which give some indication on the degrading of the detection range, were obtained with a SART in a survival craft:

a. SART lying flat on the floor

range 1.8 n miles

b. SART standing upright on the

floor range 2.5 n miles

c. SART floating in the water

range 2.0 n miles

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Survivors are advised not to deploy a SART and a radar reflector on the same survival craft because the reflector may obscure the SART.

A well mounted SART in moderate weather conditions is capable of giving a detection range of over 10n miles to a large ship radar. A poorly mounted SART, perhaps operated inside a liferaft or floating in the sea, may provide little better than visual search range to a small fishing boat radar.

Line-of-sight problems are much less of a problem for airborne detection of SARTs. With the increased sensitivity of the latest SARTs, compatible radars should have no problem in picking up SARTs at ranges up to 40n miles, given an initial search height of 3000 ft.

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4) The search craft radar controls should be as follows: (a)  receiver gain at MAXIMUM; (b) fast time constant (FTC) or anti-clutter rain (A/C rain) should

be OFF; (c) radar range should be selected, giving a receiver bandwidth

which is WIDE; (d) receiver should be DE-TUNED in order to reduce unwanted

targets such as sea clutter; (e) on approaching the SART, the receiver gain can be reduced to

eliminate the concentric arcs or circles previously described and radar range can be reduced in order to locate the exact position of the SART.

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2.7.4 OPERATION OF MARINE RADAR FOR SART DETECTION

(Safety of Navigation Circular 197) WARNING: A SART will only respond to

an X-Band (3 cm) radar. It will not be seen on an S-Band (10 cm) radar.

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Introduction 2.7.4.1 A Search and Rescue Transponder

(SART) may be triggered by any X-Band (3 cm) radar within a range of approximately 8 n mile. Each radar pulse received causes it to transmit a response which is swept repetitively across the complete radar frequency band. When interrogated, it first sweeps rapidly (0.4 µsec) through the band before beginning a relatively slow sweep (7.5 µsec) through the band back to the starting frequency.

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This process is repeated for a total of twelve complete cycles. At some point in each sweep, the SART frequency will match that of the interrogating radar and be within the pass band of the radar receiver. If the SART is within range, the frequency match during each of the 12 slow sweeps will produce a response on the radar display, thus a line of 12 dots equally spaced by about 0.64 n miles will be shown.

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2.7.4.2 When the range to the SART is reduced to about 1 n mile, the radar display may show also the 12 responses generated during the fast sweeps. These additional dot responses, which also are equally spaced by 0.64 n miles, will be interspersed with the original line of 12 dots. They will appear slightly weaker and smaller than the original dots.

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Radar Range Scale 2.7.4.3 When looking for a SART it is

preferable to use either the 6 or 12 n mile range scale. This is because the total displayed length of the SART response of 12 (or 24) dots may extend approximately 9.5 n miles beyond the position of the SART and it is necessary to see a number of response dots to distinguish the SART from other responses.

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SART Range Errors 2.7.4.4 When responses from only the 12 l

ow frequency sweeps are visible (when the SART is at a range greater than about 1 n mile), the position at which the first dot is displayed may be as much as 0.64 n mile beyond the true position of the SART. When the range closes so that the fast sweep responses are seen also, the first of these will be no more than 150 metres beyond the true position.

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Radar Bandwidth 2.7.4.5 This is normally matched to the

radar pulse length and is usually switched with the range scale and the associated pulse length. Narrow bandwidths of 3--5 MHz are used with long pulses on long range scales and wide bandwidths of 10--25 MHz with short pulses or short ranges.

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2.7.4.6 A radar bandwidth of less than 5 MHz will attenuate the SART signal slightly, so it is preferable to use a medium bandwidth to ensure optimum detection of the SART. The Radar Operating Manual should be consulted about the particular radar parameters and bandwidth selection.

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Radar Side Lobes 2.7.4.7 As the SART is approached, side

lobes from the radar antenna may show the SART responses as a series of arcs or concentric rings. These can be removed by the use of the anti-clutter sea control although it may be operationally useful to observe the side lobes as they may be easier to detect in clutter conditions and also they will confirm that the SART is near to own ship.

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Detuning the Radar 2.7.4.8 To increase the visibility of the

SART in clutter conditions, the radar may be detuned to reduce the clutter without reducing the SART response. Radars with automatic frequency control may not permit manual detune of the equipment. Care should be taken in operating the radar in the detuned condition as other wanted navigational and anti-collision information may be removed. The tuning should be returned to normal operation as soon as possible.

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Gain 2.7.4.9 For maximum range SART

detection the normal gain setting for long range detection should be used i.e., with a light background noise speckle visible.

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Anti-clutter Sea Control 2.7.4.10 For optimum range SART

detection this control should be set to the minimum. Care should be exercised as wanted targets in sea clutter may be obscured. Note also that in clutter conditions the first few dots of the SART response may not be detectable, irrespective of the setting of the anti-clutter sea control. In this case, the position of the SART may be estimated by measuring 9.5 n miles from the furthest dot back towards own ship.

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2.7.4.11 Some sets have automatic/manual anti-clutter sea control facilities. Because the way in which the automatic sea control functions may vary from one radar manufacturer to another, the operator is advised to use manual control initially until the SART has been detected. The effect of auto sea control on the SART response can then be compared with manual control.

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Anti-clutter Rain Control 2.7.4.12 This should be used normally (i.

e. to break up areas of rain) when trying to detect a SART response which, being a series of dots, is not affected by the action of the anti-clutter rain circuitry. Note that Racon responses, which are often in the form of a long flash, will be affected by the use of this control.

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2.7.4.13 Some sets have automatic/manual anti-clutter rain control facilities. Because the way in which the automatic rain control functions may vary from one radar manufacturer to another, the operator is advised to use manual initially until the SART has been detected. The effect of the auto rain control on the SART response can then be compared with manual control.

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Note: The automatic rain and sea clutter

controls may be combined in a single "auto-clutter" control, in which case the operator is advised to use the manual controls initially until the SART has been detected, before assessing the effect of auto.

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Thank you.