internationally-adopted shipborne carriage requirements for AIS
are contained in SOLAS regulation V/19. The SOLAS Convention requires
AIS to be fitted on certain ships through a phased implementation
period spanning from 1st July 2002 to 1st July 2008. In addition,
specific vessel types (e.g. warships, naval auxiliaries and ships
owned/operated by governments) are not required to be fitted with
AIS. Also, small vessels (e.g. leisure craft, fishing boats) and
certain other ships are exempt from carrying AIS. Moreover, ships
fitted with AIS might have the equipment switched off. Users are
therefore cautioned to always bear in mind that information provided
by AIS may not be giving a complete or correct picture
of shipping traffic in their vicinity. Guidance in this document
on the inherent limitations of AIS and their use in collision
avoidance situations (see paragraphs 39 to 43) should, therefore,
is intended to enhance: safety of life at sea; the safety and
efficiency of navigation; and the protection of the marine environment.
SOLAS regulation V/19 requires that AIS exchange data ship-to-ship
and with shore-based facilities. Therefore, the purpose of AIS
is to help identify vessels; assist in target tracking; simplify
information exchange (e.g. reduce verbal mandatory ship reporting);
and provide additional information to assist situation awareness.
In general, data received via AIS will improve the quality of
the information available to the OOW, whether at a shore surveillance
station or on board a ship. AIS should become a useful source
of supplementary information to that derived from navigational
systems (including radar) and therefore an important tool
in enhancing situation awareness of traffic confronting users.
1 AIS system overview
continuously transmits ship's own data to other vessels and
receives data of other vessels and VTS stations; and
When used with the appropriate graphical display, shipborne
AIS enables provision of fast, automatic information by calculating
Closest Point of Approach (CPA) and Time to Closest Point of Approach
(TCPA) from the position information transmitted by the target
operates primarily on two dedicated VHF channels. Where these
channels are not available regionally, the AIS is capable of being
automatically switched to designated alternate channels by means
of a message from a shore facility. Where no shore based AIS or
GMDSS sea Area A1 station is in place, the AIS should be switched
In practice, the capacity of the system is unlimited allowing
for a great number of ships to be accommodated at the same time.
The AIS is able to detect ships within VHF/FM range around bends
and behind islands, if the landmasses are not too high. A typical
value to be expected at sea is 20 to 30 nautical miles depending
on antenna height. With the help of repeater stations, the coverage
for both ship and VTS stations can be improved.
Information from a shipborne AIS is transmitted continuously and
automatically without any intervention or knowledge of the OOW.
An AIS shore station might require updated information from a
specific ship by polling that ship, or alternatively,
might wish to poll all ships within a defined sea
area. However, the shore station can only increase the ships
reporting rate but not decrease it.
INFORMATION SENT BY SHIPS
The AIS information transmitted by a ship is of three different
fixed, or static information, which is entered into the AIS
on installation and need only be changed if the ship changes
its name or undergoes a major conversion from one ship type
dynamic information, which, apart from Navigational status
information, is automatically updated from the ship sensors
connected to AIS; and
voyage-related information, which might need to be manually
entered and updated during the voyage.
Details of the information referred to above are given in
table 1 below:
generation, type and quality of information
(Maritime Mobile Service Identity)
Note that this might need amending if the ship changes ownership
sign and name
Note that this might need amending if the ship changes ownership
on installation or if changed
from pre-installed list
of position-fixing antenna
on installation or may be changed for bi-directional vessels
or those fitted with multiple antennae
position with accuracy indication and integrity status
updated from the position sensor connected to AIS.
The accuracy indication is for better or worse than 10 m.
Time stamp in UTC
updated from ships main position sensor connected to
over ground (COG)
updated from ships main position sensor connected to
AIS, if that sensor calculates COG.
This information might not be available.
over ground (SOG)
updated from the position sensor connected to AIS.
This information might not be available.
Automatically updated from the ships heading sensor
connected to AIS.
status information has to be manually entered by the OOW
and changed, as necessary, for example:
underway by engines
- at anchor
- not under command (NUC)
- restricted in ability to manoeuvre (RIATM)
- constrained by draught
- engaged in fishing
- underway by sail
practice, since all these relate to the COLREGS, any change
that is needed could be undertaken at the same time that
the lights or shapes were changed.
of turn (ROT)
updated from the ships ROT sensor or derived from
This information might not be available.
be manually entered at the start of the voyage using the maximum
draught for the voyage and amended as required.
(e.g. result of de-ballasting prior to port entry.)
be manually entered at the start of the voyage confirming
whether or not hazardous cargo is being carried, namely:
HS (Harmful substances)
MP (Marine pollutants)
of quantities are not required.
be manually entered at the start of the voyage and kept up
be manually entered at the start of the voyage, at the discretion
the master and updated when required.
format short text messages would be manually entered, addressed
either to a specific addressee or broadcast to all ships and
1 Data sent by ship
The data is autonomously sent at different update rates:
dynamic information dependent on speed and course alteration
(see Table 2),
and voyage-related data every 6 minutes or on request (AIS responds
automatically without user action).
0-14 knots and changing course
14-23 knots and changing course
>23 knots and changing course
2: Report Rate of Dynamic Information
safety-related messages are fixed or free format text messages
addressed either to a specified destination (MMSI) or all ships
in the area. Their content should be relevant to the safety of
navigation, e.g. an iceberg sighted or a buoy not on station.
Messages should be kept as short as possible. The system allows
up to 158 characters per message but the shorter the message the
easier it will find free space for transmission. At present, these
messages are not further regulated, to keep all possibilities
acknowledgement may be requested by a text message.
safety-related messages are only an additional means to broadcast
maritime safety information. Whilst their importance should not
be underestimated, the usage of such short safety-related messages
does not remove any of the requirements of the Global Maritime
Distress and Safety System (GMDSS).
operator should ensure that he displays and considers incoming
safety-related messages and should send safety-related messages
to SOLAS regulation V/31 (Danger messages)
The master of every ship which meets with dangerous ice,
a dangerous derelict, or any other direct danger to navigation,
or ...is bound to communicate the information by all the means
at his disposal to ships in the vicinity, and also to the competent
this is done via VHF voice communication but by all the
means now implies the additional use of the AIS short messages
application, which has the advantage to reduce difficulties in
understanding, especially when noting down the correct position.
When entering any data manually, consideration should be given
to the confidentiality of this information, especially when international
agreements, rules or standards provide for the protection of navigational
OF AIS ON BOARD
OF THE TRANSCEIVER UNIT
should always be in operation when ships are underway or at anchor.
If the master believes that the continual operation of AIS might
compromise the safety or security of his/her ship, or where security
incidents are imminent, the AIS may be switched off. This might
be the case in sea areas where pirates and armed robbers are known
to operate. Unless it would further compromise the safety or security,
if the ship is operating in a mandatory ship reporting system,
the master should report this action and the reason for doing
so to the competent authority.The
master should however restart the AIS as soon as the source of
danger has disappeared. If the AIS is shut-down, static data and
voyage related information remains stored. Restart is done by
switching on the power to the AIS unit. Ships own data will
be transmitted after a two minute initialization period. In ports
AIS operation should be in accordance with port requirements.Manual
input of data
OOW should manually input the following data at start of the voyage
and whenever changes occur using the input device such as a keyboard:
destination and ETA;
route plan (way-points);
the correct navigational status; and
safety related short messages
ensure that own ships static information is correct and
up-to-date, the OOW should check the data whenever there is a
reason for it. As a minimum, this should be done once per voyage
or once per month, whichever is shorter. The data may be changed
only on the authority of the master.
The OOW should also periodically check the following dynamic information:
positions given according to WGS 84;
speed over ground; and
After activation, an automatic built-in integrity test (BIIT)
is performed. In the case of any AIS malfunction an alarm is provided
and the unit should stop transmitting.
quality or accuracy of the ship sensor data input into AIS would
not however be checked by the BIIT circuitry before being broadcast
to other ships and shore stations. The ship should therefore carry
out regular routine checks during a voyage to validate the accuracy
of the information being transmitted. The frequency of those checks
would need to be increased in coastal waters.
OF AIS DATA
The AIS provides data that can be presented on the minimum
display or on any suitable display device as described in annex
minimum mandated display provides not less than three lines of
data consisting of bearing, range and name of a selected ship.
Other data of the ship can be displayed by horizontal scrolling
of data, but scrolling of bearing and range is not possible. Vertical
scrolling will show all the other ships known to the AIS.
AIS information is used with a graphical display, the following
target types are recommended for display:
target A sleeping target indicates only the presence of a
vessel equipped with AIS in a certain location. No additional
information is presented until activated thus avoiding information
Activated target If the user wants to know more about a vessels
motion, he has simply to activate the target (sleeping), such
that the display shows immediately:
vector (speed and course over ground),
indication (if available) to display actually initiated course
target If the user wants detailed information of a target
(activated or sleeping), he may select it. Then, the data received
as well as the calculated CPA and TCPA values will be shown in
an alpha-numeric window.
special navigation status will also be indicated in the alpha
numeric data field and not together with the target directly.
target If an AIS target (activated or not) is calculated to
pass pre-set CPA and TCPA limits, it will be classified and displayed
as a dangerous target and an alarm will be given.
target If a signal of any AIS target at a distance of less
than a preset value is not received, a lost target symbol will
appear at the latest position and an alarm will be given.
user should be familiar with the symbology used in the graphical
LIMITATIONS OF AIS
officer of the watch (OOW) should always be aware that other ships,
and in particular leisure craft, fishing boats and warships, and
some coastal shore stations including Vessel Traffic Service (VTS)
centres might not be fitted with AIS.
OOW should always be aware that other ships, fitted with AIS as
a mandatory carriage requirement, might switch off AIS under certain
circumstances by professional judgement of the master.
other words, the information given by the AIS may not be a complete
picture of the situation around the ship.
users must be aware that transmission of erroneous information
implies a risk to other ships as well as their own. The users
remain responsible for all information entered into the system
and the information added by the sensors.
The accuracy of AIS information received is only as good as the
accuracy of the AIS information transmitted.
The OOW should be aware that poorly configured or calibrated ship
sensors (position, speed and heading sensors) might lead to incorrect
information being transmitted. Incorrect information about one
ship displayed on the bridge of another could be dangerously confusing.
If no sensor is installed or if the sensor (e.g. the gyro) fails
to provide data, the AIS automatically transmits the "not
available" data value. However, the built-in integrity check
cannot validate the contents of the data processed by the AIS.
It would not be prudent for the OOW to assume that the information
received from other ships is of a comparable quality and accuracy
as that which might be available on own ship.
OF AIS IN COLLISION AVOIDANCE SITUATIONS
potential of AIS as an anti-collision device is recognized and
AIS may be recommended as such a device in due time.
AIS information may be used to assist in collision avoidance decision-making.
When using the AIS in the ship-to-ship mode for anti-collision
purposes, the following cautionary points should be borne in mind:
AIS is an additional source for navigational information. AIS
does not replace, but supports, navigational systems such as radar
target-tracking and VTS; and
the use of AIS does not negate the responsibility of the OOW to
comply, at all times, with the Collision Regulations.
The user should not rely on AIS as the sole information system,
making use of all safety-relevant information available.
use of AIS on board ship is not intended to have any special impact
on the composition of the navigational watch, which should continue
to be determined in accordance with the STCW Convention.
Once a ship has been detected, AIS can assist in tracking it as
a target. By monitoring the information broadcast by that target,
its actions can also be monitored. Changes in heading and course
are, for example, immediately apparent, and many of the problems
common to tracking targets by radar, namely clutter, target swap
as ships pass close by and target loss following a fast manoeuvre,
do not affect AIS. AIS can also assist in the identification of
targets, by name or call sign and by ship type and navigational
AND POSSIBLE FUTURE APPLICATIONS
IN VTS OPERATIONS
centres may send information about vessels which are not carrying
AIS and which are tracked only by VTS radar, via the AIS to vessels
equipped with AIS. Any pseudo AIS target broadcast by VTS should
be clearly identified as such. Particular care should always be
taken when using information which has been relayed by a third
party. Accuracy of these targets may not be as accurate as actual
directly-received targets and the information content may not
be as complete.
VTS centres may also send short messages either to one ship, all
ships or ships within a certain range or in a special area, e.g.:
management information; and
A VTS operator may request, by a text message, an acknowledgement
from the ships operator.
Note: The VTS should continue to communicate via voice
VHF. The importance of verbal communication should not be underestimated.
This is important for the VTS operator to:
vessels communicative ability; and
establish a direct communication link which would be needed
in critical situations.
(D)GNSS corrections may be sent by VTS centres via AIS.
SHIP REPORTING SYSTEMS
AIS is expected to play a major role in ship reporting systems.
The information required by coastal authorities in such systems
is typically included in the static voyage related and dynamic
data automatically provided by the AIS system. The use of the
AIS long range feature, where information is exchanged via communications
satellite, may be implemented to satisfy the requirements of some
ship reporting systems.
IN SAR OPERATIONS
may be used in search and rescue operations, especially in combined
helicopter and surface searches. AIS enables the direct presentation
of the position of the vessel in distress on other displays such
as radar or ECS/ECDIS, which facilitates the task of SAR craft.
For ships in distress not equipped with AIS, the On Scene Commander
(OSC) could create a pseudo AIS target.
AIS, when fitted to selected fixed and floating aids to navigation
can provide information to the mariner such as:
tidal and current data; and
weather and visibility conditions.
IN AN OVERALL INFORMATION SYSTEM
AIS will play a role in an overall international maritime
information system, supporting voyage planning and monitoring.
This will assist administrations to monitor all the vessels in
their areas of concern and track dangerous cargo.
IMO Recommendation on Performance Standards for a Universal
Automatic Identification System (AIS), (MSC. 74(69), annex 3).
IMO SOLAS Convention Chapter V 
ITU Radio Regulations, Appendix S18, Table of Transmitting Frequencies
in the VHF Maritime Mobile Band
ITU Recommendation on the Technical Characteristics for a Universal
Shipborne Automatic Identification System (AIS) Using Time Division
Multiple Access in the Maritime Mobile Band (ITU-R M.1371)
IEC Standard 61993 Part 2: Universal Shipborne Automatic Identification
System (AIS) Operational and Performance Requirements, Methods
of testing and required test Results.
In general, an onboard AIS (see figure 2) consists of:
multi-channel VHF receivers;
channel 70 VHF receiver for channel management;
central processing unit (CPU);
electronic position fixing system, Global Navigation Satellite
System (GNSS) receiver for timing purposes and position redundancy;
to heading and speed devices and to other shipborne sensors;
to radar/Automatic Radar Plotting Aids (ARPA), Electronic
Chart System/Electronic Chart Display and Information System
(ECS/ECDIS) and Integrated Navigation Systems (INS);
(Built In Integrity Test); and
display and keyboard to input and retrieve data.
the integral minimum display and keyboard unit, the AIS would
be able to operate as a stand-alone system. A stand alone graphical
display or the integration of the AIS data display into other
devices such as INS, ECS/ECDIS or a radar/ARPA display would
significantly increase the effectiveness of AIS, when achievable.
All onboard sensors must comply with the relevant IMO standards
concerning availability, accuracy, discrimination, integrity,
up-date rates, failure alarms, interfacing and type-testing.
a built in integrity test (BIIT) running continuously or at
monitoring of the availability of data;
an error detection mechanism of the transmitted data; and
an error check on the received data.
The connection of AIS to external navigational display systems
The AIS can be connected either to an additional dedicated
AIS display unit, and possibly one with a large graphic display,
or to an existing navigational system such as radar or an electronic
chart but in the latter case only as part of an integrated navigation
connection of AIS to external portable navigational equipment
It is becoming common practice for pilots to possess their own
portable navigational equipment, which they carry on board.
Such devices can be connected to shipborne AIS equipment and
display the targets they receive.
connection of AIS to external long-range radiocommunication
AIS is provided with a two-way interface for connecting to long
range radiocommunication equipment. Initially, it is not envisaged
that AIS would be able to be directly connected to such equipment.
A shore station would first need to request that the ship makes
a long range AIS information transmission. Any ship-to-shore
communication would always be made point-to-point, and not broadcast,
and once communication had been established, the ship would
have the option of setting its AIS to respond automatically
to any subsequent request for a ship report from that shore
Users are reminded that the SOLAS regulation V/11.10 provides
that the participation of ships in IMO-adopted ship reporting
systems shall be free of charge to the ships concerned.
AIS operates primarily on two dedicated VHF channels
(AIS1 - 161,975 MHz and AIS2 - 162,025 MHz). Where these
channels are not available regionally, the AIS is capable
of automatically switching to alternate designated channels.
required ship reporting capacity according to the IMO performance
standard amounts to a minimum of 2000 time slots per minute
(see fig. 3). The ITU Technical standard for the Universal
AIS provides 4500 time slots per minute. The broadcast mode
based on a principle called (S)TDMA (Self-organized Time
Division Multiple Access) that allows the system to be overloaded
with 400 to 500 % and still provides nearly 100% throughput
for ships closer than 8 to 10 NM to each other in a ship
to ship mode. In the event of system overload, only targets
far away will be subject to drop out in order to give preference
to targets close by, that are a primary concern for ship-to-ship
operation of AIS. In practice, the capacity of the system
is unlimited allowing for a great number of ships to be
accommodated at the same time.
OF AIS ON BOARD SHIPS
S/N circ.227 giving guidelines on the installation
FOR THE INSTALLATION OF A SHIPBORNE AUTOMATIC IDENTIFICATION
2 AIS Installation
2.1 Interference to the Ship’s VHF Radiotelephone
2.2 VHF Antenna Installation
2.3 GNSS Antenna installation
2.4 Power source
3. Bridge Arrangement
3.1 Minimum Keyboard and Display
3.2 Pilot plug
3.3 Display system
3.4 Installation of the BIIT (Built-in Integrity Test)
4. Dynamic data input
4.1 External Sensors
4.2 Position, COG and SOG
4.4 Rate of Turn
4.5 Navigational Status
5. Static Information
5.1 Entered at initial installation of AIS
5.2 Reference point of position
5.3 Ship’s dimensions
6. Long-Range function
Annex 1 Rate of Turn
Annex 2 Type of ship table
Annex 3 Recommended IEC 61162 sentences
Automatic Identification System (AIS) Class A is defined
by IMO and has been made a carriage requirement by the
latest revision of SOLAS chapter V. AIS provides information
that may be used for the navigation of the ship. It is
therefore essential that the information provided by AIS
The AIS itself has been standardised by the International
Telecommunications Union (ITU) and the International Electrotechnical
Commission (IEC) and is subject to type approval. In order
to fulfil the reliability requirements of information
exchange, care should be taken to ensure that the AIS
is correctly installed.
This document contains guidelines for manufacturers, installers,
yards, suppliers and ship surveyors. It does not replace
documentation supplied by the manufacturer.
The guidelines take into account the following conventions,
regulations, instructions and guidelines:
•IMO resolution MSC.90(73) Annex 7, Adoption of amendments
to the International Convention for the Safety of Life
at Sea, 1974, as amended.
•IMO resolution MSC.74(69) Annex 3, Recommendation on
performance standards for AIS.
•ITU Radio Regulations (RR).
•IEC 60092 (series), Electrical Installations on Ships.
•IEC 60533 Electrical and Electronic Installations in
Ships - Electromagnetic Compatibility.
Surveys on Convention ships should be carried out in accordance
with the rules laid down in resolution A.746(18) "Survey
Guidelines under the harmonised system of survey and certification",
and "Protocol of 1988 relating to the International Convention
for the Safety of Life at Sea, 1974, as amended."
For the AIS installation the following drawings shall
diagram (interconnection diagram)
initial installation configuration report should be
produced during installation and kept on board.
2.1 Interference to the Ship’ s VHF Radiotelephone
AIS shipborne equipment, like any other shipborne transceiver
operating in the VHF maritime band, may cause interference
to a ship’s VHF radiotelephone. Because AIS is a digital
system, this interference may occur as a periodic (e.g.
every 20 s) soft clicking sound on a ship’s radiotelephone.
This affect may become more noticeable when the VHF radiotelephone
antenna is located near the AIS VHF antenna and when the
radiotelephone is operating on channels near the AIS operating
channels (e.g. channels 27, 28 and 86). Attention
should be paid to the location and installation of different
antennas in order to obtain the best possible efficiency.
Special attention should be paid to the installation of
mandatory antennas like the AIS antennas.
2.2 VHF Antenna Installation
Location of the mandatory AIS VHF antenna should be
carefully considered. Digital communication is more
sensitive than analogue/voice communication to interference
created by reflections in obstructions like masts and
booms. It may be necessary to relocate the VHF radiotelephone
antenna to minimize interference effects.
minimise interference effects, the following guidelines
The cable should be kept as short as possible to minimise
attenuation of the signal. Double screened coaxial cables
equal or better than RG214 are recommended. All outdoor
installed connectors on the coaxial cables should be
waterproof by design to protect against water penetration
into the antenna cable.
cables should be installed in separate signal cable
channels/tubes and at least 10 cm away from power supply
cables. Crossing of cables should be done at right angles
(90°). Coaxial cables should not be exposed to sharp
bends, which may lead to change the characteristic impedance
of the cable. The minimum bend radius should be 5 times
the cable's outside diameter.
Coaxial down-leads should be used for all antennas,
and the coaxial screen should be connected to ground
at one end.
GNSS Antenna installation
A AIS should be connected to a GNSS antenna.
GNSS antenna should be installed where it has a clear
view of the sky. The objective is to see the horizon
freely through 360° with a vertical observation of 5
to 90° above the horizon. Small diameter obstructions,
such as masts and booms, do not seriously degrade signal
reception, but such objects should not eclipse more
than a few degrees of any given bearing. Locate the
antenna at least three meters away from and out of the
transmitting beam of high-power transmitters (S-Band
Radar and/or Inmarsat systems). This includes the ship’s
own AIS VHF antenna if it is designed and installed
separately. If a DGNSS system is included or connected
to the AIS system, the installation of the antenna should
be in accordance with IEC 61108-4, Ed 1, annex D.
achieve optimum performance, the gain of the antenna
pre-amplifier should match the cable attenuation. The
resulting installation gain (pre-amplifier gain - cable
attenuation) should be within 0 to 10 dB. The coaxial
cable between the antenna and the AIS shipborne station
connector should be routed directly in order to reduce
electromagnetic interference effects. The cable should
not be installed close to high-power lines, such as
radar or radio-transmitter lines or the AIS VHF antenna
cable. A separation of one meter or more is recommended
to avoid degradation due to RF-coupling. Crossing of
antenna cables should be done at 90° to minimise magnetic
field coupling. All outdoor installed connectors on
the coaxial cables should be waterproof by design to
protect against water penetration into the antenna cable.
AIS should be connected to an emergency power source.
installation, the AIS should be synchronised properly
on UTC and that position information, if provided, should
be correct and valid.
Minimum Keyboard and Display
functionality of the Minimum Keyboard and Display (MKD)
should be available to the mariner at the position from
which the ship is normally operated. This can be by
means of the AIS’ internal MKD (integrated or remote)
or through the equivalent functionality on a separate
pilot input/output port is part of an AIS Class A station.
A plug connected to this port should be installed on
the bridge near the pilot’s operating position so that
a pilot can connect a Personal Pilot Unit (PPU).
pilot plug should be configured as follows:
(Square Flanged (-1) or Free-Hanging (-2)), Shell size
11, 9-pin, Std. Sex 206486-1/2 or equivalent with the
TX A is connected to Pin 1
- TX B is connected to Pin 4
- RX A is connected to Pin 5
- RX B is connected to Pin 6
- Shield is connected to Pin 9
there is navigational equipment capable of processing
and displaying AIS information such as ECDIS, radar
or an integrated system available on board the ship,
the AIS Class A mobile system may be connected to that
system via the AIS Presentation Interface (PI). The
PI (input/output) should meet the requirements of IEC
display system can also include the functionality of
an MKD, see 3.1.
Installation of the BIIT (Built-in Integrity Test) function
AIS requires that an alarm output (relay) be connected
to an audible alarm device or the ships alarm system,
if available. Alternatively, the BIIT alarm system may
use the alarm messages output on the PI, provided its
alarm system is AIS compatible.
AIS has interfaces (configurable as IEC 61162-1 or 61162-2)
for position, heading and rate of turn (ROT) sensors.
In general, sensors installed in compliance with other
carriage requirements of SOLAS Chapter V should be connected
to the AIS.1 The sensor information transmitted by AIS
should be the same information being used for navigation
of the ship. The interfaces should be configured as
given in annex 3. Interfacing problems might occur if
the existing sensors found on board do not have serial
(IEC 61162) outputs.
Position, COG and SOG
sensors normally have IEC 61162 outputs for position,
COG and SOG suitable for directly interfacing the AIS.
However, it is important to note that:
- The Geodetic Datum of the position data transmitted by the sensor
is WGS 84 and that an IEC 61162 DTM sentence is configured.
- AIS is able to process two reference points for its
antenna position, one for external and one for an internal
sensor. If more than one external reference point is
used, the appropriate information needs to be input
to the AIS to adjust reference point information.
compass providing heading information is a mandatory
sensor input to the AIS. A converter unit (e.g. stepper
to NMEA) will be needed to connect AIS if the ship’s
compass does not provide an IEC 61162 output. Some ships
of less than 500 gross tonnage may not carry a compass
providing heading information.
Rate of Turn
ships may not carry a Rate-Of-Turn (ROT) Indicator according
to resolution A.526(13). However, if a rate-of-turn
indicator is available and it includes an IEC 61162
interface, it should be connected to the AIS.
ROT information is not available from a ROT indicator,
the direction of turn may (optionally) be derived from
heading information through:
simple means should be provided for the operator to
input the ship’s navigational status (e.g. underway
using engine, at anchor, not under command, restricted
in ability to maneuver, etc) information into the AIS.
The AIS may be connected to the ship's navigational
status lights. *
of the AIS does NOT establish a need to install additional
sensors above carriage requirements.
AIS standards require that certain static, voyage-related,
and dynamic information be entered manually, normally
by means of the MKD, or by means of IEC 61162 sentences
“SSD” and “VSD” via the presentation interface if such
Entered at initial installation of AIS
that should be entered at the initial installation of
the AIS includes:·
to MMSI, IMO number and other AIS controls (like
power and channel settings) will be controlled, e.g.
Call Sign, Name of Ship and Type of Ship
should be input to the AIS, either manually using the
MKD or by means of IEC 61162 sentences “SSD” and “VSD”
via the PI. Type of Ship information should be in accordance
with the table given in annex 2 (Table 18 from Rec.
example, a cargo ship not carrying dangerous goods,
harmful substances, or marine pollutants; would use
identifier “70”. Pleasure craft would use identifier
“37”. Note that those ships whose type identifier begins
with a “3” should use the fourth column of the table.
on the vessel, cargo and/or the navigational conditions,
this information may be voyage related and would therefore
need to be changed before beginning or at some time
during the voyage. This is defined by the “second digit”
in the fourth column of the table.
Reference point of position
AIS stores one “external reference point” for the external
GNSS antenna position and one “internal reference point”
if an internal GNSS is to be used as fallback for position
reporting. The locations of theses reference points
have to be set during installation using values A, B,
C, D; as described in paragraph 5.3.
external reference point may also be a calculated common
the content of the Ship Static Data (“SSD”) sentence
on the PI, including the “reference point for position”
is being processed by the AIS, and the AIS’ memory for
the “external reference point” is set in accordance
with the content of this “SSD” (e.g. used by an INS).
5.3 Ship’ s dimensions
dimensions should be entered using the overall length
and width of the ship indicated by the values A, B,
C, and D in the following figure.
dimensions (A+B and C+D) should be identical when entering
internal and external reference points.
the rare case of an EPFD antenna installed in the portside
corner of a rectangular bow, the values A and C would
be zero. Should this be the case, one of these values
should be set to 1 in order to avoid misinterpretation
as “not available” because A=C=0 is used for that purpose.
AIS’ long-range function needs a compatible long-range
communication system (e.g. Inmarsat-C or MF/HF radio as
part of the GMDSS).
this is available, a connection between that communication
system and the Class A mobile unit can be made. This connection
is needed to activate the LR function of AIS. Its input/output
port should meet the requirement of IEC 61162-2.
AIS provides the Rate of Turn (ROT) information to other
ships in order to early detect ships manoeuvres. There
are two possible parameters indicating turning of a ship
derived from two different sensors (see Figure 3: ROT
the heading from a GYRO or THD and
the rotation rate itself from a Rate of Turn- indicator.
a Rate of Turn Indicator according to resolution A.526(13)
is connected, the AIS should use this information to
broadcast both direction and value of turn on the VDL. If
valid ROT or HDG data is available from other external
sources (Gyro, INS,...), the AIS should use this information
to broadcast the direction of turn on the VDL, if greater
than 5° in 30 s (might also be implemented as 2.5° in
15 s by configuration); the AIS may also derive ROT
information from HDG internally for that purpose.
no ROT information is available, the AIS should transmit
default values indicating “not available”. ROT data
should not be derived from COG information.
a ship is not required to carry Turn-Indicator or if external
sensor fails, the AIS should react according to following