{
  "url": "https://openlegislation.uk/eu-regulation-2019-838/annex/division-5/division-5.2",
  "json_url": "https://openlegislation.uk/eu-regulation-2019-838/annex/division-5/division-5.2.json",
  "legislation": "eur/2019/838",
  "legislation_title": "Commission Implementing Regulation (EU) 2019/838 of 20 February 2019 on technical specifications for vessel tracking and tracing systems and repealing Regulation (EC) No 415/2007",
  "legislation_url": "https://openlegislation.uk/eu-regulation-2019-838",
  "path": "annex/division/5/division/5.2",
  "kind": "division",
  "number": "5.2",
  "heading": "Use of Message 21: Aids to Navigation report",
  "text": "For the use on inland waterways the AIS AtoN report (Message 21) as defined in Recommendation ITU-R M.1371 is being used. The additional European Inland types of AtoN are coded using the ‘AtoN status’ bits.\nTable 5.1\nAIS AtoN Report\nIn case an inland AtoN type code is being transmitted, this field (type of AtoN) shall be set to 0 = undefined\nWhen using Figure 5-1 for AtoN the following shall be observed:\nFor fixed AtoN, virtual AtoN, and for offshore structures, the orientation established by the dimension A shall point to true north.\nFor floating aids larger than 2 m * 2 m the dimensions of the AtoN shall always be given approximated to a circle, i.e. the dimensions shall always be as follows A = B = C = D ≠ 0. (This is due to the fact that the orientation of the floating AtoN is not transmitted. The reference point for reported position is in the centre of the circle.)\nA = B = C = D = 1 shall indicate objects (fixed or floating) smaller than or equal to 2 m * 2 m. (The reference point for reported position is in the centre of the circle.)\nFloating offshore structures that are not fixed, such as rigs, shall be considered as Code 31 type from Table 5.2. These structures shall have their ‘Dimension/reference for position’ parameter as determined above in Note (1).\nFor fixed offshore structures, Code 3 type from Table 5.2, shall have their ‘Dimension/reference for position’ parameter as determined above in Note (1). Hence, all offshore AtoN and structures have the dimension determined in the same manner and the actual dimensions are contained in Message 21.\nFor Inland AIS AtoN report this field shall be used to indicate the Inland AtoN type using page 001\nWhen transmitting virtual AtoN information, i.e. the virtual/pseudo AtoN Target Flag is set to one (1), the dimensions shall be set to A = B=C = D = 0 (default). This shall also be the case, when transmitting ‘reference point’ information\nParameter\nNumber of bits\nDescription\nMessage ID\n6\nIdentifier for this message 21\nRepeat indicator\n2\nUsed by the repeater to indicate how many times a message has been repeated\n0-3; Default = 0; 3 = do not repeat any more\nID\n30\nMMSI number, (see Article 19 of the RR and Recommendation ITU-R M.585)\nType of Aids-to-Navigation\n5\n0 = not available = default; refer to appropriate definition set up by IALA; see Figure 5-1\nName of Aids-to-Navigation\n120\nMaximum 20 characters 6-bit ASCII, as defined in Table 47 ‘@@@@@@@@@@@@@@@@@@@@’ = not available = default.\nThe name of the AtoN may be extended by the parameter ‘Name of Aids-to-Navigation Extension’ below\nPosition accuracy (PA)\n1\n1 = high (≤ 10 m) 0 = low (> 10 m) 0 = default The PA flag should be determined in accordance with Recommendation ITU-R M.1371 table ‘Determination of position accuracy information’\nLongitude\n28\nLongitude in 1/10 000 min of position of an AtoN (± 180°, East = positive, West = negative 181 = (6791AC0h) = not available = default)\nLatitude\n27\nLatitude in 1/10 000 min of an AtoN (± 90°, North = positive, South = negative 91 = (3412140h) = not available = default)\nDimension/reference for position\n30\nReference point for reported position; also indicates the dimension of an AtoN (m) (see Figure 5-1), if relevant\nType of electronic position fixing device\n4\n0 = Undefined (default)\n1 = GPS\n2 = GLONASS\n3 = Combined GPS/GLONASS\n4 = Loran-C\n5 = Chayka\n6 = Integrated Navigation System\n7 = surveyed. For fixed AtoN and virtual AtoN, the charted position should be used. The accurate position enhances its function as a radar reference target\n8 = Galileo\n9-14 = not used\n15 = internal GNSS\nTime stamp\n6\nUTC second when the report was generated by the EPFS (0-59 or 60) if time stamp is not available, which should also be the default value or 61 if positioning system is in manual input mode or 62 if electronic position fixing system operates in estimated (dead reckoning) mode or 63 if the positioning system is inoperative)\nOff-position indicator\n1\nFor floating AtoN, only: 0 = on position; 1 = off position.\nNOTE 1 — This flag should only be considered valid by receiving station, if the AtoN is a floating aid, and if time stamp is equal to or below 59. For floating AtoN the guard zone parameters should be set on installation\nAtoN status\n8\nReserved for the indication of the AtoN status\n00000000 = default\nRAIM-flag\n1\nRAIM (Receiver autonomous integrity monitoring) flag of electronic position fixing device; 0 = RAIM not in use = default; 1 = RAIM in use; see Recommendation ITU-R M.1371 table ‘Determination of position accuracy information’\nVirtual AtoN flag\n1\n0 = default = real AtoN at indicated position; 1 = virtual AtoN, does not physically exist\nAssigned mode flag\n1\n0 = Station operating in autonomous and continuous mode = default 1 = Station operating in assigned mode\nSpare\n1\nSpare. Not used. Should be set to zero. Reserved for future use\nName of Aids-to-Navigation Extension\n0, 6, 12, 18, 24, 30, 36, … 84\nThis parameter of up to 14 additional 6-bit-ASCII characters for a 2-slot message may be combined with the parameter ‘Name of Aids-to-Navigation’ at the end of that parameter, when more than 20 characters are needed for the name of the AtoN. This parameter should be omitted when no more than 20 characters for the name of the AtoN are needed in total. Only the required number of characters should be transmitted, i.e. no @-character should be used\nSpare\n0, 2, 4, or 6\nSpare. Used only when parameter ‘Name of Aids-to-Navigation Extension’ is used. Should be set to zero. The number of spare bits should be adjusted in order to observe byte boundaries\nTotal\n272-360\nOccupies two slots\nTable 5.2\nTypes of Aids to Navigation\nNOTE 1 — The types of AtoN listed above are based on the IALA Maritime Buoyage System, where applicable.\nNOTE 2 — There is potential for confusion when deciding whether an aid is lighted or unlighted. Competent authorities may wish to use the regional/local section of the message to indicate this.\nCode\nDefinition Maritime\n0\nDefault, Type of AtoN not specified\n1\nReference point\n2\nRACON\n3\nFixed structures offshore, such as oil platforms, wind farms.\n(NOTE 1 — This code should identify an obstruction that is fitted with an AtoN AIS station)\n4\nEmergency Wreck Marking Buoy\nFixed AtoN\n5\nLight, without sectors\n6\nLight, with sectors\n7\nLeading Light Front\n8\nLeading Light Rear\n9\nBeacon, Cardinal N\n10\nBeacon, Cardinal E\n11\nBeacon, Cardinal S\n12\nBeacon, Cardinal W\n13\nBeacon, Port hand\n14\nBeacon, Starboard hand\n15\nBeacon, Preferred Channel port hand\n16\nBeacon, Preferred Channel starboard hand\n17\nBeacon, Isolated danger\n18\nBeacon, Safe water\n19\nBeacon, Special mark\nFloating AtoN\n20\nCardinal Mark N\n21\nCardinal Mark E\n22\nCardinal Mark S\n23\nCardinal Mark W\n24\nPort hand Mark\n25\nStarboard hand Mark\n26\nPreferred Channel Port hand\n27\nPreferred Channel Starboard hand\n28\nIsolated danger\n29\nSafe Water\n30\nSpecial Mark\n31\nLight Vessel/LANBY/Rigs",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "In case an inland AtoN type code is being transmitted, this field (type of AtoN) shall be set to 0 = undefined"
    },
    {
      "type": "footnote",
      "label": "f2",
      "text": "When using Figure 5-1 for AtoN the following shall be observed: For fixed AtoN, virtual AtoN, and for offshore structures, the orientation established by the dimension A shall point to true north. For floating aids larger than 2 m * 2 m the dimensions of the AtoN shall always be given approximated to a circle, i.e. the dimensions shall always be as follows A = B = C = D ≠ 0. (This is due to the fact that the orientation of the floating AtoN is not transmitted. The reference point for reported position is in the centre of the circle.) A = B = C = D = 1 shall indicate objects (fixed or floating) smaller than or equal to 2 m * 2 m. (The reference point for reported position is in the centre of the circle.) Floating offshore structures that are not fixed, such as rigs, shall be considered as Code 31 type from Table 5.2. These structures shall have their ‘Dimension/reference for position’ parameter as determined above in Note (1). For fixed offshore structures, Code 3 type from Table 5.2, shall have their ‘Dimension/reference for position’ parameter as determined above in Note (1). Hence, all offshore AtoN and structures have the dimension determined in the same manner and the actual dimensions are contained in Message 21."
    },
    {
      "type": "footnote",
      "label": "f3",
      "text": "For Inland AIS AtoN report this field shall be used to indicate the Inland AtoN type using page 001"
    },
    {
      "type": "footnote",
      "label": "f4",
      "text": "When transmitting virtual AtoN information, i.e. the virtual/pseudo AtoN Target Flag is set to one (1), the dimensions shall be set to A = B=C = D = 0 (default). This shall also be the case, when transmitting ‘reference point’ information"
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eur/2019/838/annex/division/5/division/5.2",
    "retrieved_at": "2026-11-01T14:43:22.038059+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}