Automatic Identification System (AIS)
Safety at sea
The Automatic Identification System (AIS) provides fast, automatic and accurate information in order to reduce the risk of collisions.
What is the Automatic Identification System?
The AIS is a Very High Frequency (VHF) radio broadcasting system which enables AIS equipped vessels and shore-based stations to send and receive identifying information.
This information can:
- be displayed on a computer or chart plotter
- aid in situational awareness
- provide a means to assist in collision avoidance.
The International Maritime Organization (IMO) defines AIS as a ship and shore-based broadcast system, operating in the VHF maritime band.
The AIS can handle over 2,000 reports per minute and may update information as often as every two seconds.
There are two types of shipborne AIS:
- AIS Class A
- AIS Class B.
AIS Class A
AIS Class A has been mandated by the IMO through the Safety of Life at Sea Convention (SOLAS), for:
- vessels of 300 gross tonnage and upwards engaged on international voyages
- cargo ships of 500 gross tonnage and upwards not engaged on international voyages
- passenger ships, irrespective of size, which carry more than 12 passengers.
AIS Class B
AIS Class B provides less functionality than an AIS Class A and is intended for non-SOLAS vessels and pleasure craft.
The IMO does not mandate for AIS Class B to be installed.
There are also different types of non-shipborne AIS, including:
- AIS used for shore stations (AIS Base Stations)
- AIS Aids to Navigation (AIS AtoN)
- AIS Search and Rescue Transmitters (AIS SART)
- AIS fitted to Search and Rescue Aircraft (SAR aircraft)
- Man Overboard units (AIS MOB).
Automatic Identification System FAQ
Do you have a question about the Automatic Identification Systems? Answers to many commonly asked questions are below. Please click on the question to reveal the answer.
What is the Automatic Identification System (AIS)?
- AIS is a maritime communications device. It uses the Very High Frequency (VHF) radio broadcasting system to transfer data.
- AIS equipped vessels and shore-based stations can send and receive identification information that can be displayed on an electronic chart, computer display or compatible navigation radar.
- AIS improvea navigation safety and environmental protection by assisting in the effective navigation of ships. The information provided by AIS can help in situational awareness and provide a means to assist in collision avoidance. In addition, AIS can be used as an aid to navigation by providing location and additional information on buoys and lights.
What types of AIS are there?
- There are AIS units and AIS stations. There are AIS units carried on board vessels, AIS carried on board aircraft to support maritime safety (for example, search and rescue aircraft), AIS base stations, AIS aids to navigation, and AIS man overboard units.
- AIS carried on board vessels can be what is called ‘AIS Class A’ and ‘AIS Class B’.
- AIS base stations and AIS aids to navigation are often called ‘non-shipborne AIS’.
- More information on AIS can be found on the AMSA Automatic Identification System page. This includes a link to an interactive tutorial on AIS.
What is the difference between AIS Class A and AIS Class B?
- AIS is included in the International Convention for the Safety of Life at Sea (SOLAS) convention for: vessels vessels of 300 gross tonnage and upwards engaged on international voyages, vessels of 500 gross tonnage and upwards not engaged on international voyages as well as passenger ships irrespective of size. The AIS referred to in the SOLAS convention is often termed ‘AIS Class A’.
- AIS Class B is intended for use on non-SOLAS vessels. A non-SOLAS vessel is a vessel to which the SOLAS convention does not apply. These can include domestic commercial vessels and pleasure craft. AIS Class B units have less functionality than Class A units but they operate and communicate with AIS Class A units and other types of AIS units.
Where can I find out more information on AIS and how it works?
- AIS works automatically and continuously, regardless of where a vessel is located. There are two dedicated frequencies used for AIS – AIS 1 (channel 87B) and AIS 2 (channel 88B).
- Each frequency is divided into 2250 time slots that are repeated every 60 seconds, and the AIS units send packets of information which are transmitted in these ‘slots’.
- More information on how AIS works can be found on the AMSA website. This includes a link to an interactive tutorial on AIS.
How do I install and program my AIS?
- Installed AIS devices should consider the guidelines developed by the International Maritime Organization (IMO Safety of Navigation Circular 227 - GUIDELINES FOR THE INSTALLATION OF A SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEM). Programming an AIS unit depends on specific manufacturerrequirements.
- AIS Class A units are user configurable, however there may need a password to change programmed information. Static data must be programmed correctly – such as ship name, maritime mobile service identity (MMSI) number, length, breadth, etc.
- AIS Class B units may not be user configurable, and owners may need to contact the manufacturer or retailer for instructions.
- All AIS units require a MMSI to operate. MMSIs are allocated according to international standards.
Information on getting an MMSI in Australia.
Do I need to register my AIS?
AIS units are not ‘registered’ in the same manner as EPRIBs or emergency beacons. However, all AIS units require a maritime mobile service identity (MMSI) to operate.
MMSIs are allocated according to international standards.
What are the requirements for carriage of AIS?
- Marine Orders are regularly amended in response to changes in international law, industry requirements, and technological developments. They provide an efficient means of implementing Australia‘s international maritime obligations. AMSA Marine Orders - this will take you to the ComLaw website where you can view or download the Marine Order you are interested in.
- Specific information on AIS carriage requirements can be found in Marine Order 21 (Safety of navigation and emergency procedures) 2012.
- Marine Order 63 highlights the obligations within Australian waters (which are defined in the order) for the MASTREP reporting system.
- Additional information specific to domestic commercial vessels can be found in the National Standards for Commercial Vessels page.
Are fishing vessels subject to AIS carriage? Is VMS an acceptable substitute for AIS?
- Fishing vessels may be required to carry AIS, butany vessel may switch off its AIS if the master believes continual operation may compromise the safety or security of the vessel.
- Requirements for AIS are identified in Marine Order 21. It's application includes: regulated Australian vessels, foreign vessels in an Australian port; entering or leaving an Australian port; in the internal waters of Australia or in the territorial sea of Australia other than in the course of innocent passage.
- Vessel Monitoring Systems (VMS) use a different technology to AIS, and VMS are not an acceptable substitute for AIS. Information on VMS can be found on the AFMA website.
Is AIS used for Long Range Identification and Tracking (LRIT)?
Long Range Identification and Tracking (LRIT) was adopted by the International Maritime Organization (IMO) as an amendment to Chapter V of SOLAS, and came into force on 1 January 2008.
LRIT is not the same as AIS, and AIS is not used for LRIT.
Why am I sometimes unable to see a vessel name, MMSI number or other information on AIS?
Shipboard AIS units autonomously broadcast different AIS messages:
- a 'position report' which includes latitude, longitude, position accuracy, time, course, speed, navigation status
- a 'static and voyage related report' which includes name, dimensions, type
- information regarding its voyage (e.g. static draft, destination, and ETA).
Position reports are broadcasted frequently (between 2-10 seconds depending on the vessel’s speed, or every 3 minutes if at anchor), while static and voyage related reports are sent every six minutes.
It is common for an AIS user to receive numerous position reports from a vessel before the vessel’s name and type, etc.
When I am looking at a website for AIS how come I sometimes don’t see vessels?
- The publicly available AIS websites (such as Marinetraffic.com) are a crowd-based approach to AIS information. The International Maritime Organization (IMO) has condemned the display of AIS on public websites. The AIS receivers used for this purpose are not certified AIS base stations and may not provide accurate or valid data.
- Under SOLAS and the relevant IMO guidelines, the Master of any vessel has the discretion to turn off the AIS unit if its continual operation might compromise the vessel's safety or security.
What if I have a question on AIS that isn’t answered here?
If you have a question on AIS that isn’t answered here or by reviewing the AIS information available on the Automatic Identification System page on the AMSA website, you can contact us.
- Flowchart - Establishing an AIS Base Station [ PDF: 47Kb]
- Flowchart - Establishing a Real AIS Aton [ PDF: 49Kb]
- Flowchart - Establishing a New Virtual Synthetic AIS Aton [ PDF: 44Kb]
- AMSA Guidelines for the use of non-shipborne AIS units
- AMSA Guidelines for AIS on offshore structures
- Forms: AMSA 234a /234b
- Simplified Ship Notification Form