Vessel Traffic Service (VTS) Port Arthur

Important AIS Information

AIS Carriage Requirements

  • AIS Class A devices - The following vessels are required to have on board a properly installed, operational Coast Guard type-approved AIS Class A device:
    1. Self-propelled vessels of 65-feet of more in length, engaged in commercial service;
    2. Towing vessels of 26-feet or more in length and more than 600-horsepower, engaged in commercial service;
    3. Self-propelled vessels certificated to carry more than 150 passengers;
    4. Self-propelled vessels engaged in dredging operations in or near a commercial channel or shipping fairway in a manner likely to restrict or affect navigation of other vessels;
    5. Self-propelled vessels engaged in the movement of:
      1. Certain dangerous cargo as defined in subpart C or part 160 of this chapter (33 CFR 161.202)
      2. Flammable or combustible liquid cargo in bulk that is listed in 46 CFR 30.25-1, Table 30.25-1
  • AIS Class B devices - The following vessels that are required to carry an AIS Class A device may use a Coast Guard type-approved AUS Class B device if they are not subject to pilotage by other than the vessel Master or crew: 
  1. Fishing industry vessels
  2. Vessels identified in paragraph above (Class A, item 1) that are certificated to carry less than 150 passengers and that:
    1. Do not operate in a VTS or VMRS area defined in Table 161.12(c) of section 161.12 of this chapter; and
    2. Do not operate at speeds in excess of 14 knots; and
    3. Vessels identified in paragraph above (Class A, item 4) engaged in dredging operations.

Note to paragraph (b): Under 33 U.S.C. 1223(b)(3) and 33 CFR 160.111, a Coast Guard Captain of the Port (COTP) may restrict the operation of a vessel if he or she determines that by reason of weather, visibility, sea conditions, port congestion, other hazardous circumstances, or the condition of such vessel, the restriction is justified in the interest of safety. In certain circumstances, if a COTP is concerned that the operation of a vessel not subject to §164.46 would be unsafe, the COTP may determine that voluntary installation of AIS by the operator would mitigate that concern. Fishing industry vessels include fishing vessels, fish processing vessels, and fish tender vessels as defined in 46 U.S.C. 2101.


AIS Operating Requirements

  1. Use of AIS does not relieve the vessel of the requirements to sound whistle signals or display lights or shapes in accordance with the International Regulations for Preventing Collisions at Sea, 1972 (72 COLREGS), 28 U.S.T. 3459, T.I.A.S. 8587, or Inland Navigation Rules, 33 CFR part 83; nor of the radio requirements of the Vessel Bridge-to-Bridge Radiotelephone Act, 33 U.S.C. 1201-1208, part 26 of this chapter, and 47 CFR part 80.
  2. AIS must be maintained in effective operating condition, which includes—

    (i) The ability to reinitialize the AIS, which requires access to and knowledge of the AIS power source and password;

    (ii) The ability to access AIS information from the primary conning position of the vessel;

    (iii) The accurate broadcast of a properly assigned Maritime Mobile Service Identity (MMSI) number;

    (iv) The accurate input and upkeep of all AIS data fields and system updates; and

    (v) For those vessels denoted in paragraph (b) of this section, the continual operation of AIS and its associated devices (e.g., positioning system, gyro, converters, displays) at all times while the vessel is underway or at anchor, and, if moored, at least 15 minutes prior to getting underway; except when its operation would compromise the safety or security of the vessel or a security incident is imminent. The AIS should be returned to continuous operation as soon as the compromise has been mitigated or the security incident has passed. The time and reason for the silent period should be recorded in the ship's official log and reported to the nearest Captain of the Port or Vessel Traffic Center (VTC).

  3. AIS safety-related text messaging must be conducted in English and solely to exchange or communicate pertinent navigation safety information (analogous to a SECURITE broadcast). Although not prohibited, AIS text messaging should not be relied upon as the primary means for broadcasting distress (MAYDAY) or urgent (PAN PAN) communications. (47 CFR 80.1109, Distress, urgency, and safety communications).
  4. AIS application-specific messaging (ASM) is permissible, but is limited to applications adopted by the International Maritime Organization (such as IMO SN.1/Circ.289) or those denoted in the International Association of Marine Aids to Navigation and Lighthouse Authorities' (IALA) ASM Collection for use in the United States or Canada, and to no more than one ASM per minute.

Note to paragraph (d): The Coast Guard has developed the “U.S. AIS Encoding Guide” to help ensure consistent and accurate data encoding (input) by AIS users. This Guide is available at our “AIS Frequently Asked Questions” (FAQ #2) World Wide Web page at Although of great benefit, the interfacing or installation of other external devices or displays (e.g., transmitting heading device, gyro, rate of turn indicator, electronic charting systems, and radar), is not currently required except as denoted in §164.46(c). Most application-specific messages require interfacing to an external system that is capable of their portrayal, such as equipment certified to meet Radio Technical Commission for Maritime Services (RTCM) electronic chart system (ECS) standard 10900 series.



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