8 - 3

CHAPTER 8

COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

CHAPTER 8 SETS FORTH INSTRUCTIONS AND PROCEDURES FOR U.S. MERCHANT VESSELS TO ESTABLISH COMMUNUCATIONS IN ORDER TO RECEIVE AND SEND INFORMATION TO/FROM THE HOMELAND DEFENSE (HLD) ORGANIZATION, NAVAL COOPERATION AND GUIDANCE FOR SHIPPING (NCAGS), DURING NORMAL OPERATIONS OR TIMES OF CRISIS.

.

PART I U.S. NAVAL COOPERATION AND GUIDANCE FOR SHIPPING (NCAGS

800A. General

The purpose of this section is to provide guidance to ship

owners, operators, Masters, and officers on the

arrangements for Naval Cooperation and Guidance for

Shipping (NCAGS) in order to enhance the safety of

merchant ships and to support military operations. It

provides information on the provision of NCAGS support.

In periods of crisis, conflict, national emergency or war,

naval authorities may direct the movement of merchant

ships (including routing and diversion) so that they may be

better protected from hostilities and not interfere with

possible active Naval and/or Joint Military Operations. The

NCAGS organization is the principal U.S. resource to carry

out this function. The purpose of NCAGS is to ensure the

efficient management and safe passage of merchant ships.

This mission primarily involves:

– the establishment of an organization and framework for

communicating directions, advisories, concerns, and/or

information among operational forces, merchant

shipping, and maritime organizations;

– the deconfliction of merchant vessel sailings/operations,

for safety to preclude interference with naval activities;

– and making recommendations to the theater/ operational

commander on the extent and type of protection that may

be provided to merchant shipping.

800B. History of NCAGS

NCAGS was formerly known as NCAPS (Naval

Coordination and Protection of Shipping). NCAPS was

originally established to meet a Cold War-era national need

to protect merchant shipping against a global open ocean

threat. NCAPS policy included escorting and routing of

large convoys of merchant shipping.

The threat to merchant shipping has changed and so has

the Naval Control of Shipping (NCS) mission. The primary

threat to U.S. merchant vessels is no longer considered to

be traditional naval vessels under the flag of a known

enemy; instead, the threat is terrorism. The NCAGS

mission is to provide U.S. military commanders the

information necessary to provide Maritime Domain

Awareness (MDA). The goal of MDA is to assist in

Homeland Defense (HLD) by maintaining as much

real-time information as possible regarding merchant

shipping, such as positions, destinations, cargo, etc. As a

result, the NCAGS organization can provide U.S. and

allied merchant vessels the information needed to 

prevent terrorist attacks at sea or inport.

800C. NCAGS Organization

NCAGS doctrine has evolved with the changing 

posed both on merchant shipping and by me

shipping in the context of regional operations and ma

HLD. The NCAGS organization addresses bot

traditional protection and control of shipping in a r

and the emerging requirement of maritime HLD, 

merchant shipping may be either the protagonist, or 

requiring the establishment of communications to in

maritime situational awareness of merchant ship

NCAGS doctrine applies to maritime HLD, contin

support, and general economic shipping.

Types of contingency support shipping include 

vessels of the Military Sealift Command (MSC), shi

operated or chartered by the U.S. Government to su

naval operations or to meet U.S. policy objectives, 

response shipping, and relief shipping chartere

government agencies.

Types of economic shipping include vessels enga

normal commercial trade worldwide, regardless of fl

ownership, or such other shipping that is not und

control or direction of the U.S. Government.

Specific to maritime HLD operations in the U

States Northern Command (USNORTHCOM) Ar

Responsibility (AOR), a new organization was deve

in an effort to execute the required mission to im

maritime HLD and to support the USCG as the lead f

agency for maritime Homeland Security (HLS). A

element of the Joint Force Maritime Comp

Commander (JFMCC), the NCAGS organization pro

direct support to USNORTHCOM’s mission of cond

operations to deter, prevent, and defeat maritime t

and aggression. NCAGS works jointly with the U

States Coast Guard (USCG). The NCAGS organi

consists of Shipping Coordination Centers (S

geographically positioned to assist in improving me

shipping coordination and providing posi

information of merchant vessels operating in 

USNORTHCOM AOR. The SCCs are the first s

creating a global merchant vessel tracking capabili

the maritime domain.
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 4

800D. Questions and Comments

Ship’s Officers, ship owners, and operators are

encouraged to submit questions and comments on

procedures outlined in this chapter to:

U.S. FLEET FORCES COMMAND

MR. ERIC SHAFFER N35

1562 MITSCHER AVENUE SUITE 250

NORFOLK VA 23551-2487
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 5

THE WORLD WITH U

S

COMMANDERS’ AREAS OF RESPONSIBILITY
PART II COORDINATION WITH NCAGS

810A. General

The primary organization responsible for executing the

NCAGS mission is the Shipping Coordination Center

(SCC). A SCC bridges the gap between military leaders

responsible for HLD and U.S. merchant shipping. NCAGS

support provided by the SCC includes military

cooperation, guidance, advice, assistance, and supervision

to merchant shipping to enhance the safety of U.S. and

allied merchant ships and to support military operations by

maintaining awareness of merchant shipping positions

around the U.S. The purpose of NCAGS is to make use of

cooperation between military and civil maritime

authorities and agencies and the commercial shipping

industry in order to facilitate an uninterrupted flow of

maritime commerce in periods of peace and conflict and

simultaneously minimize disruption to military operations.

The cooperation and frequent exchange of information

achieve this goal. An accurate assessment of the merchant

shipping picture is critical to the accomplishment of this

goal. Masters will be asked to provide basic information

concerning their ship, cargo, and voyage details. In times

of increased tension or conflict, additional information

may be requested. The response of Masters to information

requests is one of the most important aspects of NCAGS.

The commercial sensitivity of the information supplied by

the merchant shipping community will be respected and

protected.

The NCAGS organization will in turn ensure that

appropriate military authorities are advised of these details

for monitoring during the voyage. If deemed necessary,

they will provide the merchant Master with up-to-date

information concerning the situation and specific

information on the voyage. This information can range

from basic situation briefs to the provision of routes, lead

through, or escort. Safe passage responsibility remains

with the Master.

The principal benefits of NCAGS to merchant shipping

include:

– Improved safety and security.

– Minimized disruptions to passages through areas where

military operations are being conducted.

– Quicker reaction to terrorism.

– A better understanding of military constraints.

– Minimized disruption to commercial schedules.

The principal benefits of NCAGS to the military

commander include:

– A more comprehensive picture of merchant activity and

positions of merchant ships.

– Deconfliction of merchant ships in military operations.

– Enhanced safety and security of merchant ships.

– Improved effectiveness of military operations.

– A better understanding of commercial constraints.

810B. Elements of the NCAGS

The NCAGS is flexible in order to meet the need

military commander and merchant shipping. 

comprise some or all of the following elements tai

suit the situation depending on the level of N

support required.

– Shipping Coordination Center (SCC): The SC

permanent organization, tasked with establishi

maintaining links with the military, merchant sh

HLD and HLS agencies, such as the USCG. T

will:

– Provide MDA by maintaining a merchant s

plot of the assigned AOR.

– Generate Notice to Mariners (NOTMA

necessary regarding acts of terrorism or 

operations.

– Advise civil maritime authorities, via M

Administration (MARAD), of general shippin

in the area.

– Establish Shipping Risk Areas (SRAs

recommend routing of shipping.

– Shipping Coordination Team (SCT): The SCT 

expeditionary team that can be deployed to a 

region to gather information on local merchant s

and naval operations and will provide the means 

merchant shipping on risks, routing, and organiza

protection. The SCT will, depending on the lev

operation, encompass coordination and guidance 

military commanders and merchant Master

location of SCTs can be ashore or afloat. The SCT 

with local and regional authorities includin

authorities, shipping agents, and local s

companies and reports ship movements to local 

commanders to help deconflict military operatio

merchant shipping.

– NCAGS Liaison Officer (LNO): An officer d

aboard a merchant ship to provide liaison betw

merchant ship Master and military authorities. Th

is the naval advisor to the merchant Master. His 

on board does not affect the Master’s responsibil

the safe navigation and safe handling of the sh

LNO makes military knowledge available to the 

to allow the Master to understand the naval and 

requirements that are applicable.

– Shipping Risk Area (SRA): When necessary, a SR

be recommended by a SCC or SCT. A SR

geographically defined portion of the NCAG

where an elevated risk to merchant shipping exist

can include potentially hostile acts, navi

restrictions that require an elevated closer mana

of shipping traffic, or naval forces operations th

conflict with routine safe passage. More than o

can be established within an NCAGS area. SR

established by the local military commander.
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 7

PART III COMMUNICATIONS WITH NCAGS

820A. General

The role of NCAGS in keeping the seas safe and

providing the essential framework needed to allow

commercial and military shipping to operate together in a

crisis is dependent on effective communications with

merchant shipping at sea or inport. The SCC or SCT will

exchange data at the unclassified level with merchant

shipping authorities and with elements of the NCAGS

organization. This part provides guidance to Masters who

may need to communicate with military forces.

Communications with merchant ships by the military are

accomplished via the Global Maritime Distress and Safety

System (GMDSS) and other commercial means. Under

normal circumstances, ships working with NCAGS will

maintain their normal peacetime communications.

However, if the situation so dictates, they may be required

to maintain additional communications methods.

820B. Methods of Communication

GMDSS: Every effort is made by the NCAGS

organization to provide communications for merchant

vessels to either the SCC or SCT so that ships can

communicate easily and regularly with them using

Inmarsat-C. Generally telex, fax, email, and voice, when

available, are used as the primary means for the NCAGS

organization to contact ships either through owners,

directly to the ships if this has been made available, or via

commercial organizations who specialize in passing

messages.

Navigational Warnings (NAVWARNs)/Notice to

Mariners (NOTMARs): The military authorities will pass

safety information for the NCAGS AOR, promulgated by

broadcast methods, via NAVWARNs, NOTMARs, and

MARAD Advisories. These warnings will describe

possible military operations in an AOR. Notices will

include toll free telephone numbers a merchant Master or

agent can call to obtain real-time information regarding an

ongoing crisis or military operation.

Military Points of Contact: A SCC, SCT, or NCAGS

LNO can provide merchant shipping with their main

means of communications in an elevated risk situation via

GMDSS, NAVWARNs/NOTMARs, or embarked LNO.

Communication Reporting Gate (CRG): In an AOR,

there is a good possibility that your ship will be called, or

challenged, by naval vessels or military aircraft on the

VHF calling frequency. To allow merchant ships to contact

naval vessels in the AOR, information will be distributed

directly to the Master via LNO, naval vessels in the local

area, or local advisory notices by various means including,

but not limited to, NOTMARs, e-mail, or websites.

However, naval units can normally be contacted through

standard calling VHF frequencies.

CRG is established to provide a position/line for

merchant ships to call NCAGS in order to establish initial

contact or to update previous information. A CRG 

be positioned in such a way that a minimum notice 

of 36 hours is available to merchant ships to conta

owners/operators for onward passage instructions 

reaching the AOR. The CRG will normally be repr

as lines of latitude or longitude that encompasses 

concerned.

Ships will be notified of the CRG details for th

and the reporting requirements will be promulg

merchant ships through a variety of means, such a

SCC, SCT advisory notices, or NAVWARNs. Inst

will normally contain details of the information r

the occasions of reporting, and to whom the report 

sent. Ships will be asked to forward a Format Alfa 

arriving at the CRG.

820C. Forms and Message Formats

(Ref: ATP-2, Vol. II)

Format Alfa: Format Alfa is the principal me

which merchant ship data is collected for use 

NCAGS. The Format Alfa will be requested 

forwarded at least 24 hours prior to entering the 

operations and then, if possible, every 6 hours until 

the area of operations. The form is divided in

sections:

– Section A covers basic details of the vessel.

– Section B covers details of the current voyage.

– Section C covers details of the ship’s operator.

– Section D covers cargo data.

NOTE: Date and Time should be entered either 

date followed by a four digit time (18.Oct 97 21.0

or a Date-time Group (DTG). The military me

expressing date and time is contained within the D

is written in the following manner:

DDHHMMZ MON YY

therefore, the DTG 182100Z JUL 98 describes a 

21:00 (GMT/UTC) on the 18 July 1998. Militar

routinely describe GMT/UTC as time zone 

abbreviated to “Z.”

– Section A - Ship Data:

(1) Ship’s name.

(2) International callsign.

(3) Type of vessel.

(4) Flag of registry.

(5) IMO number.

(6) Port of registry.

(7) Overall length.

(8) Vessel’s width.

(9) Maximum draft for present voyage.

(10) Vessel’s gross tonnage.

(11) Speed:

(a) Service speed.

(b) Maximum speed.
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 8

(c) Minimum speed.

(12) Significant appearance of vessel for optical

recognition.

(13) Inmarsat/DSC number.

(14) Name of communication station being copied.

(15) State whether pocket-sized automatic crypto

equipment (PACE) and keying material is held.

(16) Fax number.

(17) Email address or telex number.

(18) Other communication means.

– Section B - Voyage Data:

(19) Intended movement - description of passage.

(20) Last port/country of call including actual date and

time of departure from last port.

(21) Next port of call, including ETA at next port of call.

(22) Current position.

(23) Date/time and position entering the region.

(a - x) Waypoints of intended track through AOR

(date/time - latitudes/longitudes).

(24) Position and date/time of departing the region.

– Section C - Operator Data:

(25) Name of ship owner/operator including address of

ship owner, name of charterer (if any), and address of

operator/charterer.

(26) Flag of ship operator.

(27) Email address of the above.

(28) Telephone number of above.

(29) Fax number of above.

– Section D - Cargo Data:

(30) Quantity and nature of main/relevant cargo.

(31) Shippers of main/relevant cargo (name and

address).

(32) Origin of main/relevant cargo.

(33) Consignee of main/relevant cargo.

(34) Final destination of main/relevant cargo.

(35) Special queries appropriate to current operation

such as “State if any cargo/person is carried being

subject to UN sanctions, by YES or NO (if the answer to

the query is YES, then describe on a separate sheet).”

Ship Data Cards: Ship Data Cards are amplifications of

the information provided by the merchant ship on the

Format Alfa that is used to facilitate cooperation between

merchant ships and military assets. Masters will be asked

to supply only information that is not available from other

open sources, such as agents and the Internet.

Sailing Instructions (SI): SI are issued to a

transiting a SRA and any other ships requiring 

guidance. The issue of a SI indicates that the Ma

accepted the routing guidance contained within 

NCAGS will monitor the ship’s passage and divert 

if the threat or risk changes and a diversion messa

be sent to the Master.

Diversion Order: A message from NCAGS ord

diversion from the existing route for any reason. T

words of the text will be the identifier “DIVE

ORDER” followed by:

(1) The reason for diversion.

(2) The position or time at which the diversion is to 

place.

(3) New positions through which ships are to pass. 

position is to be preceded by its two letter designato

(4) The immediate destination and amended ETA.

Example:

DIVERSION ORDER

(1) Acts of terrorism in your vicinity.

(2) Divert at position AB.

(3) Pass through new positions BL 4245N04800

4230N05500W, then to original position AE and 

track.

(4) Amended ETA Baltimore 160800Z Jan.

Passage Amendment: This message is to be se

ship to report passage amendments involving cha

destination or differences of greater than 6 hours v

from the original passage plan intentions repo

Format Alfa. The message will be addressed to the 

addressee of the Format Alfa. The first words of 

will be the identifier “FORMAT ALFA PA

AMENDMENT” followed by:

(1) The international call sign, IMO number, and n

the ship.

(2) Position at . . . . . .

(3) Great circle or rhumb line track and speed.

(4) Name of next port of call.

(5) ETA at next port of call.

Example:

FORMAT ALFA PASSAGE AMENDMENT

(1) WGLW, 9076236, SS YOUNG AMERICA.

(2) 4315N 03515W at 181500Z Aug.

(3) Rhumb line/l9.

(4) Baltimore.

(5) 221200Z Aug.
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 9

PART IV CONTAMINATION PREDICTION SYSTEM FOR MERCHANT SHIPS AT 

AND THE MERWARN SYSTEM

830A. Significance of NBC Warnings

Radioactive fallout from nuclear explosions and chemical

and biological contamination (hereafter collectively referred

to as contamination) on sea and land targets, particularly the

latter, may affect large areas of adjacent waters. The areas

affected will depend upon the prevailing wind conditions, and

any ship close to or approaching these areas will be in grave

danger. It is therefore essential that shipping should be warned

of the fallout hazards and contamination in order that:

– Passive defense measures, such as activating washdown

systems, may be taken.

– Course may be altered, if necessary, to avoid the

dangerous zones.

830B. The MERWARN System, Warnings to

Merchant Ships at Sea

A simplified contamination warning system has been

established throughout NATO for broadcasting, via

MERCOMMS and coastal radio stations, warnings of

contamination dangerous to merchant shipping. This

system calls for the origination, by NATO naval

authorities, of five types of messages:

– MERWARN NBC Effective Downwind Message

(MERWARN NBC EDM).

– MERWARN NBC 3 NUC.

– MERWARN NBC Chemical Downwind Message

(MERWARN NBC CDM).

– MERWARN NBC 3 CHEM.

– MERWARN DIVERSION ORDER.

In some cases it may be better to provide warning of

contamination by means of general plain language

messages rather than by these formats.

830C. MERWARN Originating and Diversion

Authorities

MERWARN Originating and Diversion authorities will

be designated by national or NATO commanders before

commencement of operations.

830D. Precedence of NBC Messages

All MERWARN NBC messages should be given FLASH

(Z) precedence to ensure rapid handling on any military

circuit between the originating authority and the

MERCOMMS and/or coastal radio stations. This

precedence should not be used where the rules for the use of

the international safety signal (SECURITAY for voice

circuits) apply.

830E. Method of Promulgation

All MERWARN NBC EDM, MERWARN NBC 

MERWARN NBC 3 CHEM and NBC 3 NUC m

will be transmitted in plain language, using 

preceded by the international safety signal, fr

appropriate MERCOMMS station and from all the 

radio stations of the area concerned. Masters n

concern themselves with the identity of the MER

originators, but only with the sea areas covered 

message.

830F. Relay Responsibilities

Originating authorities are responsible for relayin

– The appropriate Coast Earth Station (Inmarsa

Coast Radio Station (CRS) under their control

other CRS in their geographic area.

– Their own national authorities (for transmis

merchant ships not yet copying MERCOMMS).

– Adjacent MERWARN originators and shipping d

authorities within the geographical area affected 

MERWARN NBC 3 NUC message.

NOTE: Adjacent MERWARN originator

responsible for relaying to CES/CRS under their co

necessary.

830G. Danger Zones

All shipping in waters out to 200 nautical miles fr

coast at the outset of war must be regarded as bein

area of possible fallout danger from nuclear att

shore.

830H. MERWARN NBC EDM

MERWARN NBC EDM is a prediction, for a s

sea area and time interval, of the fallout which wi

from a 1 megaton (MT) nuclear surface explosion

give the Master of a ship, observing a nuclear explo

immediate indication of the area likely to be affe

fallout.

MERWARN NBC EDM will be issued at 1

intervals from the time of activation of the MERC

system, and will be valid 12 hours ahead from the d

time given in the first line of the message (line A)

event of changing meteorological conditions it 

necessary for the originating authorities to 

MERWARN NBC EDM more frequently. The 

MERWARN NBC EDM will automatically be ov

by the latest MERWARN EDM issued.

The following standard format will be used:
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 10

A. Message identifier (MERWARN NBC EDM) and

date-time group (GMT) from which valid for 12 hours

ahead.

B. Specified sea area for which valid.

C. Effective downwind direction (in degrees, three digits)

and effective downwind speed (in knots, three digits).

D. Downwind distance of Zone 1 (in nautical miles, three

digits).

E. Additional information.

Example:

A. MERWARN NBC EDM 180600ZSEP1999

B. BALTIC SEA WEST OF 15°00′E

C. 045-020

D. 078

E. NIL

NOTE: Sets B, C, and D may be repeated for different sea

areas should this be considered necessary.

830I. MERWARN NBC 3 NUC, Standard

Format

MERWARN NBC 3 NUC will be issued after a nuclear

attack producing fallout, and gives fallout data for a

specific explosion or series of explosions, which will be

identified in the message.

MERWARN NBC 3 NUC messages are issued as soon

as possible after the attack, and at 6 hour intervals (to the

nearest hour) thereafter, for as long as fallout danger exists.

They contain information which enables the Master of a

ship to plot the danger area.

The standard format of MERWARN NBC 3 NUC

contains the sets ALFA, DELTA, FOXTROT, and PAPAB

of the military NBC 3 NUC message.

The MERWARN NBC 3 NUC has the following

structure:

Example:

MERWARN NBC 3 NUC

ALFA/UK/NBCC/02-001/N//

DELTA/021405ZSEP1999//

FOXTROT/451230N014312E/AA//

PAPAB/012KTS/028NM/02NM/272DGT/312DGT

830J. MERWARN NBC 3 NUC, Plain Langu

Format

The MERWARN NBC 3 NUC standard format m

be suitable after a multiple nuclear attack which p

fallout from several bursts in a large or comple

area. In such cases warnings will be plain la

statements of a more general nature, indicatin

affected and expected movement of the fallout.

Example 1:

MERWARN NBC 3 NUC

ALFA/UK/02-001/N//

DELTA/021405ZSEP1999//

Fallout extends from Glasgow area to eastern Ire

021405Z and is spreading westwards with 12 Kno

Sea is likely to be affected within an area of 60 

miles of the British coast.

Example 2:

MERWARN NBC 3 NUC

ALFA/IT/15-001/N//

DELTA/150630ZFEB1999//

Fallout is estimated to be occurring at 150830

Adriatic Sea east of the coast line Bari/Brindisi 

distance of 30 nautical miles. Fallout is 

south-eastwards with 016 Knots, getting weaker. I

expected to be dangerous after 151000Z.

830K. MERWARN NBC CDM

The MERWARN NBC CDM message c

information needed for CHEM/BIO hazard predic

the master of a merchant ship. The MERWARN 

CDM will be issued as required via the MERCOM

will be valid as specified. In the event of change

meteorological conditions, the MERWARN NBC 

will be updated as required.

The following standard format will be used:

MERWARN NBC 3 NUC (Message identifier)

ALFA: Strike Serial Number (as defined by the naval

authority).

DELTA: Date-time Group of detonation (GMT).

FOXTROT: Location of attack (latitude and longitude, or

geographical place name) and qualifier (two

digits as follows: AA=Actual Location,

EE=Estimated Location).

PAPAB: Effective wind speed (three digits and unit of

measurement), downwind distance of Zone 1

(three digits and unit of measurement), cloud

radius (two digits and unit of measurement),

left and right radial line of the predicted

fallout hazard area (three digits and unit of

measurement each).

ALFA: Message identifier (MERWARN NBC 

date-time group (GMT) from which v

hours ahead.

BRAVO: Specified sea area for which valid.

CHARLIE: Representative downwind direction (

3 digits) and representative downwin

(knots, 3 digits).

DELTA: Maximum downwind hazard 

(nautical miles, 3 digits).
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 11

Example:

830L. MERWARN NBC 3 CHEM

This message is issued to pass immediate warning of a

predicted chemical contamination and hazard area.

MERWARN NBC 3 CHEM reports are issued as soon as

possible after each attack. They contain sufficient

information to enable the master of a ship to plot the

downwind hazard area.

The following standard format will be used for

MERWARN NBC 3 CHEM:

NOTE: If representative downwind speed is 5 knots or less,

or variable, this letter item will consist of three (3) digits

instead of coordinates, representing the radius of a circle in

nautical miles centred on the location of the attack

contained in set FOXTROT.

NOTE: Some of the letter items above may not be

completed in the report that is received, but there will be

sufficient information for a Downwind Hazard plot to be

carried out.

The MERWARN NBC 3 CHEM standard format may

not be suitable after a multiple chemical attack, which

produces a hazard from several attacks or depositions in a

large or complex target area. In such cases warnings will

be plain language statements of a more general nature,

indicating areas affected and expected movemen

hazard.

Example 1:

MERWARN NBC 3 CHEM

ALFA/DA/NBCC-4/003/C//

DELTA/020300ZSEP1999//

GENTEXT/PERSISTENT NERVE AGENT 

HAZARD EXISTS FROM NORFOLK TO HAT

AT 020300Z SEP 1999 AND IS SPRE

SOUTH-EASTWARDS AT 017 KNOTS. SEA 

OUT TO 100 NAUTICAL MILES FROM 

LIKELY TO BE AFFECTED BY 020600ZSEP199

Example 2:

MERWARN NBC 3 CHEM

ALFA/DA/NBCC-3/003/C//

DELTA/020300ZSEP1999//

GENTEXT/PERSISTENT NERVE AGENT 

HAZARD AT 020600Z SEP 99 IS ESTIMATED 

OCCURRING OVER MOST OF THE SEA AREA

TO 40 MILES EAST OF THE COAST LINE 

NORFOLK TO HATTERAS. HAZARD IS EXP

TO HAVE DISPERSED BY 021000Z SEP1999//

830M. MERWARN DIVERSION ORDER

In addition to the origination of MERWARN NB

and MERWARN NBC 3 NUC messages, naval aut

may, if circumstances dictate, broadcast general d

orders, based upon the fallout threat, whereby m

ships proceeding independently will be passed 

routing instructions of a more general nature, us

standard NCS identifier MERWARN DIVE

ORDER.

Example:

A. MERWARN DIVERSION ORDER

B. English Channel closed. All shipping in No

remain north of 052 degrees N until 031500ZSE

830N. Other Warnings

ATP-2, Vol II, gives instructions for the dis

signals by ships which have received a MERWARN 

NUC message which affects their area. Ships arrivi

sea but remaining beyond visual/aural range o

stations should continue to keep radio watch in o

receive MERWARN messages.

830O. Ground Zero

The point at the surface on sea or land imm

below or above a nuclear explosion is called Grou

(GZ).

ECHO: Additional information.

ALFA MERWARN NBC CDM 180600ZSEP1999//

BRAVO BALTIC SEA WEST OF 15°00′E//

CHARLIE 045/020//

DELTA 010//

ECHO NIL//

MERWARN NBC 3 CHEM (Message identifier)

ALFA: Strike Serial Number (as defined by the naval

authority).

DELTA: Date-time group (Z) of start and end of attack.

FOXTROT: Location of event.

GOLF: Delivery Means.

INDIA: Release Information.

PAPAA: Predicted attack and hazard area.

YANKEE: The representative downwind direction and

speed.

ZULU: Information on actual weather conditions.

GENTEXT: Remarks.
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 12

830P. Effective Downwind Direction and

Downwind Speed

Winds in the atmosphere vary considerably with height,

both in direction and speed, and have a major influence on

the distribution of radioactive fallout from a nuclear cloud.

The worst contamination will fall to the surface along a

path represented by the average wind between the surface

and the middle of the nuclear cloud.

Based upon meteorological information on the wind

conditions in the airspace between the surface and the

height of the nuclear cloud, NBC Collection Centers will

compute the average direction and speed of the radioactive

particles’ path from the nuclear cloud to the surface.

The results of this computation make up the fallout

prediction, expressed in the terms of effective downwind

direction and speed. It should be noted that the direction of

the effective downwind is the direction towards which the

wind blows. This direction is also known as the fallout

axis.

The surface wind will usually be considerably different

from the effective downwind, both in direction and speed,

and the surface wind should never be used to estimate the

drift of fallout.

830Q. Fallout Pattern Criteria

The predicted fallout area consists of two zones, Zone 1

and Zone 2, with the following characteristics:

– Zone 1 is the zone of immediate concern. Within this

zone there will be areas where exposed, unprotected

personnel may receive doses of 150 cGy (rads) or

greater, within 4 hours. Casualties among personnel may

occur within portions of this zone.

– Zone 2 is the zone of secondary hazard. Within this zone

the total dose received by exposed, unprotected

personnel is not expected to reach 150 cGy (rads) within

a period of 4 hours after the actual arrival of fallout, not

even when the radioactive fallout remains on the deck of

the ship.

Outside these two zones the risk will be negligible.

830R. Fallout Plotting in Merchant Ships

When a nuclear explosion is reported in a MERWARN

NBC 3 NUC message, the Master of a merchant ship

should immediately plot the fallout area on a chart, using

the information contained in the message. A plot example

accompanies the next section.

When a MERWARN NBC 3 NUC is not available (for

example, when a nuclear detonation is observed from the

ship) the data contained in the current MERWARN NBC

EDM should be used. The plotting procedures are almost

identical in the two cases.

For purposes of simplification, merchant ships are to use

cloud radii and safety distance as follows:

– Plotting from MERWARN NBC EDM: Use cloud radius

10 nautical miles and safety distance 15 nautical miles in

all cases.

– Plotting from MERWARN NBC 3 NUC: Use th

radius given in the MERWARN NBC 3 NUC an

cases, a safety distance of 15 nautical miles.

Plotting should be performed in the following ma

– Plot the location of the detonation (ground zero

chart. Look up the fourth and fifth field of set 

(left and right radial line of the fallout area) and c

the bisector. This line is the equivalent to the do

direction. Draw a downwind axis from GZ 

downwind direction, as calculated above. Dr

additional downwind radial lines from GZ, 20 ̊ t

side of the downwind axis.

– Using GZ as center and the downwind distance 

1 (second field of set PAPAB) as radius, draw 

between the two radial lines on each side 

downwind axis. Draw a second arc between th

lines to represent Zone 2, doubling the do

distance for radius.

– Using GZ as center, draw a semicircle upwind (o

the downwind axis and radials) using the cloud 

(third field of set PAPAB).

– From the intersections of the Zone 1 arc with 

radial lines, draw straight lines to the ends of th

radius semicircle.

– To determine the area in which fallout depos

predicted to occur at any given time after the deto

– Multiply the effective downwind speed (first fiel

PAPAB) by the time after the burst (in hours), th

being a distance in nautical miles.

– To and from this distance add and subtract a 

distance of 15 nautical miles to allow for finit

size, diffusion, and wind fluctuations. The result 

two distances.

– With GZ as center and the two safety distances o

above as radii, draw arcs across the plotted fallou

– The area enclosed between the two arcs will con

most cases, the area of deposition of fallout 

particular time after the burst.

830S. Plotting from MERWARN NBC 3 NUC

Example:

Given:

MERWARN NBC 3 NUC

ALFA/UK/NBCC/09-001/N//

DELTA/091715ZSEP1999//

FOXTROT/PLYMOUTH/AA//

PAPAB/018KTS/040NM/05NM/275DGT/315DGT

Problem: Determine the predicted fallout area 

area within which fallout is predicted to deposi

surface at 091845ZSEP1999.

Solution (See figure.):

– On the chart plot GZ. Calculate the downwind d

295 degrees as bisector from left and right rad

(from set PAPAB, fourth and fifth field). D

downwind axis from GZ on a bearing of 295
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 13

distance of 80 nautical miles. Draw two radial lines from

GZ, bearing 275 ̊ and 315 ̊, both 80 nautical miles long.

(80 is twice the downwind distance of Zone 1.)

– Using GZ as center, draw arcs between the radial lines at

40 nautical miles downwind to mark Zone 1, and at 80

nautical miles downwind to mark Zone 2.

– From the third field of set PAPAB, the cloud radius is 5

nautical miles. With GZ as center and 5 nautical miles as

radius, draw the cloud radius semicircle upwind of GZ.

– From the intersections of the Zone 1 arc with the radial

lines, draw straight lines to the ends of the cloud radius

semicircle.

– 091845Z is 1.5 hours after the burst. From the first field

of set PAPAB, obtain the effective downwind speed; 18

knots:

18 kts x 1.5 hr = 27 nautical miles.

The safety distance is always 15 nautical miles.

27 + 15 = 42 nautical miles, and 27 - 15 = 12 

miles.

– With GZ as center and 42 and 12 nautical miles 

draw arcs across the fallout pattern. The area encl

the two arcs and the boundary of the pattern is 

within which fallout is predicted to deposit at the 

at 091845ZSEP1999.

830T. Contamination Plotting in Merchant Sh

When a chemical attack is reported in a MER

NBC 3 CHEM message, the following procedure sh

followed:

– Plot the location of the attack from the detail

FOXTROT.

– Plot the coordinates or radius of the circle conta

set PAPAA.
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 14
COMMUNICATION INSTRUCTIONS FOR U.S. MERCHANT SHIPS

8 - 15

APPENDIX A

INSTRUCTION TO MASTERS IN AN EMERGENCY ON DEFENSE AGAINST NUCLEAR FALLOU

Attacks with nuclear weapons may be expected on land

targets adjacent to your route. Such attacks are likely to

result in radioactive fallout being deposited over large

areas of sea, through which you may have to pass. It may

be possible to issue a general warning to indicate which

areas are likely to be dangerous at any particular time.

As fallout will probably be in the form of fine dust which

may be invisible, you should observe the following

precautions during nuclear fallout.

If your ship is equipped with the necessary instruments

to detect fallout, these precautions may be relaxed

accordingly.

PRECAUTIONS TO BE TAKEN: If your ship has a

prearranged radioactive countermeasure plan prepared,

ensure that all measures laid down in that plan are carried

out. If no such plan is in existence, improvise measures as

indicated below:

– Select a group, or groups, of compartments as low in the

ship and as far removed from the ship’s side as possible

within which the crew can take shelter. These spaces

should be equipped with washing and lavatory facilities,

and sufficient food should be stowed there to last for the

passage through the dangerous area. Spaces selected

should be capable of being completely shut down with

all ventilation and other openings secured.

– Strike below or cover as much gear on the weather decks

as possible, particularly absorbent materials such as line,

awnings, etc. Ensure that food stores and galleys are

secured with all openings closed. Stop all ventilation

fans and close or cover all ventilation and other openings

which are not essential for running machinery and

continued steaming. In the absence of suitable closures,

the use of canvas covers, adhesive tape, etc., is

recommended.

– Rig all available fire-fighting and deck washing hoses

and nozzles to spray water continuously over as much of

the weather decks and superstructure as possible, to

prevent contamination settling. If complete cover

impossible, concentrate effort on the navigating po

over the top of the shelter position(s), and abov

machinery spaces.

– If a continual spraying of the upper wor

impracticable, organize working parties at fre

intervals to wash down the weather decks 

superstructure to reduce the buildup of contaminati

– Reduce the number of your crew who must rema

the weather decks or in positions near the weather 

or in machinery spaces, to the bare minimum req

for safe steaming, and keep the remainder in the se

shelter position(s).

– Ensure that all who must remain in exposed pos

(including machinery spaces, unless ventilation c

stopped) are fully clothed, preferably in foul w

clothing, with all the skin covered so far as practica

– During the passage, so far as the numbe

appropriately skilled personnel allow, change a

those manning exposed or relatively unshe

positions (including the machinery spaces) as of

possible in order to spread the radiation d

Remember that this advice also applies to the M

who should take as much shelter as the safe navigat

the ship will permit.

– Ensure that all who have been exposed remove a

their outer clothing on returning to shelter, 

thoroughly their exposed skin (especially hands, 

and neck) as soon as possible, and in any case b

drinking or eating.

– Restrict unnecessary movement throughout the s

minimize the possible spread of contamination.

– Unless absolutely necessary, do not distill wat

drinking while in a dangerous area.

– As soon as possible after clearing a dangerous area

out a thorough hosing down of the all weather deck

superstructure.