6 JUNE 2017 • FOGHORN FOGHORNFOCUS: OPERATIONS P ersonal flotation devices (PFDs) are among the most visible symbols of maritime safety. Perhaps more crucial to the crew’s safety but not nearly as visible is the vessel’s Automatic Identification System (AIS). AIS is a situational awareness tool for collision avoidance. AIS is autonomous and therefore con- tinuously exchanges real-time safety and navigation informa- tion between AIS equipped vessels within VHF range of each other. Recognizing the important role AIS has on our nation’s maritime safety and security, the U.S. Coast Guard developed Nationwide AIS (NAIS), which consists of an expansive network of shore-based VHF towers that receive AIS trans- missions from vessels transiting U.S. waterways. Together, NAIS and AIS play a critical role in ensuring our nation’s maritime safety. AIS Data Collectively, AIS data falls into three categories: Static, Dynamic, and Voyage-related Data. Static Data is informa- tion that must be programmed into the AIS at installation and verified periodically. Static Data includes; Maritime Mobile Service Identity (MMSI), Vessel Type, Vessel Name, Callsign (if assigned), IMO or Official Documentation Number (if assigned), and the vessel’s AIS positioning system and antenna location (which is also is used to provide vessel dimensions). Dynamic Data, such as position, course, speed, heading, and rate of turn is autonomously acquired from external or internal sensors (i.e. GPS, speed log, heading device or gyro). Dynamic Data is continuously broadcasted every few seconds. Proper installation and operation of all sensors is critical to the proper operation of AIS and the information it exchanges. Voyage related data (i.e. Navigation Status, Static Draft, Destination, and Estimated Time of Arrival) is manually inputted and should always be kept up to date. Navigation Status must be updated throughout the course of a voyage. Vessels underway broadcast every 2-10 seconds, whereas vessels that are moored or at anchor broadcast every 3 minutes. Moored vessels that use an underway Navigation Status consume significantly more NAIS bandwidth. Bandwidth and throughput are crucial factors that may affect the response times of first responders that use NAIS information. Vessel should use the correct Navigation Status to remain compliant with federal regulations and to ensure NAIS performs at optimal levels. AIS Discrepancies Vessels that transmit incorrect AIS data can increase the risk of collision, especially in congested waterways or during low vis- ibility conditions. For example, an alarming number of AIS users do not accurately report their dimension. Knowing or not knowing the location of the bow of a large vessel you are approaching will have a direct affect on how you react while maneuvering close to that vessel. AIS regulations (33 CFR 164.46) require AIS users to always broadcast accurate and up-to-date AIS information, and that their vessel is identifiable with a properly assigned MMSI. NAIS tracks almost 12,000 vessels daily, the majority of which broadcast inaccurate and/or outdated information. The most common discrepancies are: • Improper use of MMSIs. Vessels with MMSI discrep- ancies transmit fictitious, expired, and/or duplicative MMSI. A valid MMSI must be obtained from the Federal Communication Commission (FCC) or one of the designated private registration agent(s) for all AIS equipped vessel. The MMSI is a core component of AIS and MUST be accurate. • Vessels that broadcast incorrect Vessel Name and/or Call Sign. These discrepancies are serious because they are used to identify and hail vessels, which is of particular importance when vessels are in distress. The transmission of inaccurate information may result in delays, when time is of the essence. • Vessels that do not broadcast dimensions or dimensions that are inaccurate. At installation, an AIS should be pro- grammed with the antenna location of the AIS positioning source (i.e. the vessel’s or AIS’s GPS, as values calculated to the bow, stern and sides of the vessel). This data is in turn used on the receiving end to allow the user to see an outline of the vessel centered at the position location of the AIS broadcast. Fantastic Voyage: The Importance of Transmitting Accurate AIS Data By Ensign David Turay, United States Coast Guard WHAT VESSELS MUST HAVE AIS? As of March 1, 2016, an operable AIS unit must be carried by (1) every passenger vessel with a capacity for 150 or more; and (2) every passenger vessel, regardless of capacity, that is 65 feet or more in length and that is in commercial service.