MAY NOT BE DISCERNIBLE WITH OLDER AIS SOFTWARE
The U.S. Coast Guard is pleased to announce the availability of
type-approved Automatic Identification System (AIS) Class B devices. These
lower cost AIS devices are interoperable with AIS Class A devices and make
use of expanded AIS messaging capabilities. Unfortunately, not all
existing Class A devices are able to take full advantage of these new
messaging capabilities. All existing AIS stations will be able to receive
and process these new messages from a Class B device. However, they may
not be able to display all Class B information on their Minimum Keyboard &
Display (MKD) or other onboard navigation systems. In most cases, a
software update or patch will be required to do so. Therefore, the U.S.
Coast Guard cautions new AIS Class B users to not assume that they are
being ‘seen’ by all other AIS users or that all their information is
available to all AIS users. Further, the U.S. Coast Guard strongly
recommends that all users of out-dated AIS software update their systems
as soon as practicable.
The new Class B devices have the same ability to acquire and display
targets not visible to radar (around the bend, in sea clutter, or during
foul weather). They differ slightly in their features and nature of
design, which reduces their cost and affects their performance. They
report at a fixed rate (30 seconds) vice the Class A’s variable rate
(between 2-10 seconds dependent on speed and course change). They consume
less power, thus broadcast at lower strength (2 watts versus 12 watts),
which impacts their broadcast range; but, they broadcast and receive
virtually the same vessel identification and other information as Class A
devices, however, do so via different AIS messages.
Class A devices by design will receive the newer Class B AIS messages and
their MKDs should display a Class B vessel’s dynamic data (i.e. MMSI,
position, course and speed), unfortunately, there are a few older models
that do not. Although these older devices might not display the new AIS
messages, they are designed-and tested-to receive and process these
messages and make them available to external devices (e.g. electronic
chart systems, chart plotters, radar) via a Class A output port. These
external devices may also require updating in order to discern Class B
equipped vessels.
AIS automatically broadcasts dynamic, static, and voyage-related vessel
information that is received by other AIS-equipped stations. In
ship-to-ship mode, AIS provides essential information that is not
otherwise readily available to other vessels, such as name, position,
course, and speed. In the ship-to-shore mode, AIS allows for the efficient
exchange of information that previously was only available via voice
communications with Vessel Traffic Services. In either mode, AIS enhances
a user’s situational awareness, makes possible the accurate exchange of
navigational information, mitigates the risk of collision through reliable
passing arrangements, facilitates vessel traffic management while
simultaneously reducing voice radiotelephone transmissions, and enhances
maritime domain awareness. The U.S. Coast Guard encourages its widest use.
The U.S. Coast Guard advises mandated AIS users that Class B devices do
not meet current AIS carriage requirements-either the International
Convention for the Safety of Life at Sea (SOLAS V/19.2.4) or U.S.
regulations (33 CFR 164.46). The Coast Guard is in the process of
expanding the current carriage requirements to include most self-propelled
commercial vessels which navigate U.S. waters, and the use of Class B
devices will be permissible on some of these commercial vessels.
Prospective buyers, particularly those operating commercial vessels that
are highly maneuverable, travel at high speed, or routinely transit
congested waters or in close-quarter situations with other AIS equipped
vessels should consider, albeit more expensive, AIS Class A devices in
order to meet forthcoming requirements.
All users are reminded to maintain their AIS in effective operating
condition at all times, including the information the AIS device
broadcasts. Improper operation of AIS or inaccurate information could
subject a person to civil penalties not to exceed $25,000 (46 USC §70119).
For general information on AIS, carriage requirements, future AIS
rulemakings and a listing of Coast Guard type-approved AIS Class A devices
which require a software update in order to display AIS Class B
information, visit http://www.navcen.uscg.gov/enav/ais .
This safety alert is provided for informational purposes only and does not
relieve any domestic or international safety, operational or material
requirement. Developed by the Office of Waterways Management, United
States Coast Guard Headquarters, Washington, DC, cgnav@uscg.mil.
