Australian Maritime Safety Authority

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)?

What types of AIS are there?

What is the difference between AIS Class A and AIS Class B?

Where can I find out more information on AIS and how it works?

How do I install and program my AIS?

Do I need to register my AIS?

What are the requirements for carriage of AIS?

Are fishing vessels subject to AIS carriage? Is VMS an acceptable substitute for AIS?

Is AIS used for Long Range Identification and Tracking (LRIT)?

Why am I sometimes unable to see a vessel name, MMSI number or other information on AIS?

When I am looking at a website for AIS how come I sometimes don’t see vessels?

What if I have a question on AIS that isn’t answered here?

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