Automatic Identification System ( AIS )

What is AIS? 
General

The Automatic Identification System (AIS) is an international standard for ship-to-ship, ship-to-shore,
and shore-to-ship data communication approved by the International Maritime Organization (IMO). AIS shipboard equipment consists of a transceiver that continually transmits and receives vessel

navigational information (identity, position, course, speed, etc.) over VHF-FM maritime frequencies. AIS units operating in proximity to each other automatically create a virtual network. Shore stations can also join these virtual networks, and they may receive shipboard AIS signals, perform network and frequency management, and send additional broadcast or individual informational messages to AIS equipped vessels. In 2002, the IMO began a phased program requiring vessels on international voyages to carry AIS equipment. As of December 31, 2004, most commercial vessels engaged in international voyages and vessels that transit a U.S. VTS area are required to carry this equipment. Additional information on AIS can be found at the USCG Navigation Center’s web site, www.navcen.uscg.gov/enav/ais/.

AIS - Automatic Identification System

is a short range coastal tracking system used on ships and Vessel Traffic Services (VTS) to identify and locate the ship by electronic data interchange with other ships and VTS stations nearby. Such as unique identification information, position, course and speed can be displayed on the screen or ECDIS. AIS is intended to assist the ship's officers watchstanding and allow maritime authorities to track and monitor vessel movements, and integrate the VHF transceiver system standards such as Loran-C or Global Positioning System receiver, with other electronic navigation sensors, such as the gyrocompass or turn rate indicator.

The International Maritime Organization (IMO) International Convention for the Safety of Life at Sea (SOLAS) requires AIS to be fitted aboard international voyaging with gross tonnage (GT) or more than 300 tons, and all passenger ships regardless of size. It is estimated that morethan 40,000 ships currently carry equipment AIS grade A.

AIS ships beyond the reach of radio can be traced to the Long Range Identification and Tracking (LRIT) system with a transmission of less frequent.

What IS Automatic Identification System (AIS)?

Ship radar screen image, with overlaid electronic chart the data, which includes the mark for every significant ship within radio range, each as desired with a velocity vector (indicating speed and heading). Each ship "mark" could reflect the actual size of the ship, with position to GPS or differential GPS accuracy. By "clicking" on the sign of the ship, you could learn the ship name, course and speed, classification, call sign, registration number, MMSI, and other information. Maneuver information, closest point of approach (CPA), time to closest point of approach (TCPA) and other navigation information, more accurate and more timely than information available from an automatic radar plotting aid, could also be provided. Display information previously available only to modern Vessel Traffic Service center operations can now be available for each vessel equipped with AIS. Ship radar screen images, New Media Graphics Electronic Data overlay, which is still ongoing signs related to the article includes a significant ship within radio range, as each new article shows the desired velocity vector (speed and Pos) "related is still ongoing. Ship" could reflect the actual size of the sign of Ships, article New Media Position for GPS differential GPS accuracy Danijel. New article "clicking" sign IN Ship, Anda Can Learn Ship Name, and speed courses, classification, call sign, registration number, MMSI and Information Attorney Information lying. Maneuver, the closest point of approach (CPA), time to closest point USING approach (TCPA) and Other Information navigation, more accurate and more timely information available USING A radar subscribe to My USING auto aid plan, also provided information. Gmail previously available only for articles similar: a model approach to modern Vessel Traffic Center can now be available for liabilities related article continues AIS-equipped ships.

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AIS is a ship broadcast system that acts like a transponder, operating in the VHF maritime band, that is capable of handling more than 4,500 reports per minute and updates as often as every two seconds. Using Self-Organizing Time Division Multiple Access (SOTDMA) technology to meet high broadcast rate and ensure the operation of the ship-to-ship reliable. AIS is a broadcast system that acts as a subscription Ship My transponder, operating VHF Maritime band ON, USING A more capable of handling the update rate 4.500 per minute back as often associated Seconds And prayer is still ongoing. Using Self-Organizing Time Division Multiple Access (SOTDMA) technology to meet the Press Articles High and Reliable ensure liabilities Ship-to-Ship.

 

Applications and limitations

Avoid collision

AIS is used in navigation, especially to avoid a collision. Due to the limitations of VHF radio communications, and because not all vessels equipped with AIS, the system is intended to be used primarily as a means of finding and determine the risk of collision and not as an automatic collision avoidance system, according to the International Regulations Preventing Collisions at Sea (COLREGS).

An AIS vessels display only text, a list of close range ships', bearing, and the name

When a ship navigating at sea, movement and identity of the other boats around it is very important for the navigator to make the decision to avoid collisions with other vessels and hazards (shallow or stone). Visual observation (without assistance, binoculars, night vision), the exchange of audio (whistle, horn, VHF radio), and radar or Automatic Radar Plotting Aid (ARPA), which has historically been used for this purpose.However, the lack of positive identification of the target on the display, and the time delays and other limitations of radar to observe and quantify the actions and responses from the ship around, especially in the busy waters, it is sometimes possible to prevent the action in time to avoid collision.

While the AIS requirement to display only the very basic text information, the data obtained can be integrated with electronic charts or graphics radar screen, providing navigation information consolidated on a single screen.

Vessel traffic services

In the busy waters and ports, a local ship Traffic Service (VTS) may exist to regulate ship traffic. Here, the AIS provides additional traffic awareness and provide information about other types of ships and their movements.

Aid to navigation

AIS was developed with the ability to broadcast its position and name of the other objects from boats, such as a navigation aid and marker position. This assistance can be located on the coast, such as in a lighthouse, or on the water, on a platform or buoy.U.S. Coast Guard indicate that the SIA will replace RACON, or a radar beacon, currently used for electronic navigational aids.

The ability to broadcast the position of the navigation aid also created the concept of synthetic AIS and Virtual AIS. In the first case, the transmission of SIA describes a physical marker positions but the signal itself is derived from a transmitter located elsewhere. For example, an on-shore base station can broadcast the position marker float ten channels, each of which is too small to contain the transmitter itself. In the second case, it could mean AIS transmissions are showing signs that do not exist physically, or concerns that are not visible (ie submerged rock, or a ship destroyed).Although virtual assistance will only be seen by the AIS equipped ships, low cost to maintain them can lead to their use as a physical marker is not available.

Search and rescue

For the coordination of resources at the location of marine search and rescue operations, it is important to know the position and status of ships navigating around the ship or the person in trouble. Here the SIA can provide additional information and awareness of resources for the operation of the scene, though the range is limited to AIS VHF radio range. AIS standard also envisions the possibility of using SAR aircraft, and includes a message (AIS Message 9) to report the position of the aircraft. To aid SAR vessels and aircraft to find people in trouble-Sart standard for AIS AIS Search and Rescue Transmitter is being developed by the International Electrotechnical Commission (IEC), the standard is scheduled to be completed in late 2008 and AIS-SARTs will be available in the market beginning in , 2009.

Accident Investigation

AIS information received by the VTS is important for the investigation of the accident to provide accurate time, identity, positioning by GPS, compass heading, course over ground (COG), Speed (with log / SOG), and rate of turn (ROT) of the vessel involved in the accident analysis, rather than limited information (position, COG, SOG) radar echo by radar.

Maneuver the accident information is important to understand the actual movement of the ship before the accident, especially for collisions, grounding accidents.

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