Message ID

6

Identifier for this message; always 28.

Repeat Indicator

2

Used by the repeater to indicate how many times a message has been repeated. See § A2-4.6.1 0-3; 0 = default; 3 = do not repeat any more.

Source ID

30

Identity (in the MMS) of the source of the message (see RR Art. 19 and Rec. ITU-R M.585)

Time stamp

6

UTC second when the report was generated by the electronic positioning fixing system (EPFS), (0-59); 60 = time stamp is not available = default; 61 = EPFS is in manual input mode; 62 = EPFS is in dead reckoning mode; 63 = EPFS is inoperative

Longitude

28

Longitude in 1/10 000 min of position of an AtoN (±180°, East = positive, West = negative, 181 = (6791AC0h) = not available = default)

Latitude

27

Latitude in 1/10 000 min of an AtoN (±90°, North = positive, South = negative, 91 = (3412140h) = not available = default)

Restricted Use Indicator

2

Indicates where the AtoN may be operated.

0 = unrestricted use = default
1 = use restricted to the territorial waters of the flag state (of MMSI MID)
2 = use restricted to the Exclusive Economic Zone (EEZ) of the flag state (of MMSI MID)
3 = use restricted as defined by its flag state (of MMSI MID)

NOTE – Use outside of a restricted area requires permission of the AtoN’s flag state (of MMSI MID) competent authority.

AIS AtoN Station Type

3

Indicates the type of AIS AtoN station. See IALA Recommendation R0126, The Use of the AIS in Marine AtoN Services, R1016, Mobile Marine Aids to Navigation (MAtoN) and IMO MSC Circular 1473, Policy on Use of AIS Aids to Navigation.

0 = a physical AIS AtoN (floating)
1 = a physical AIS AtoN (fixed)

2 = a synthetic predicted AIS AtoN
3 = a synthetic monitored AIS AtoN
4 = a virtual AIS AtoN
5 = a mobile AIS AtoN
6-7 = reserved for future use

Types of AtoN

7

0 = not available = default in maritime service 1-127 = refer to message 21 Table 72 or Table 85).

IALA AtoN MRN

17

AtoN unique IALA Marine Resource Name (MRN). national identification number. The MMSI MID represents the nationality.

000001-131 071, 0 = not available or unassigned = default

See IALA Guideline G1143, IALA MRN for AtoN, e.g. urn:mrn:iala:aton:<ISO 3166-1 alpha-2 code for its nationality>:<national identification number>.

Parameter

Bits

Description

AtoN Dimensions Type

4

Defines what Dimensions A and B represent.

0 = AtoN Dimensions Type = default (see Message 21 and § A7-3.19.1)

1 = AtoN Height and Structural Area. The reported position represents the midpoint of a shape that encompasses the structural area of the AtoN (i.e. buoy, ODAS, platform, bridge, building, tower, wind turbine, etc.).

- Dimension A = radius of the circle, in 1-metre steps, 0-511, 511 = 511 metres or greater.

- Dimension B = its height above sea level, in 0.1-metre steps, 0-204.7, 204.7 = 204.7 metres or greater. Intended to convey the physical dimensions of a large AtoN or the structure it resides on and assists its sightings.

2 = AtoN Swing Circle. If Type of AtoN > 19 < 31, the reported position also represents the centre of its swing circle.

- Dimension A (in 100-metre steps, 0–51 100) + Dimension B (in 1-metre steps, 0–100) = its radius. Dimension B = 101-2 047 reserved for future use.

3 = Mobile AtoN Vector. Dimension A = COG, in true degrees: 0-359 in 1‑degree steps, 360 = COG unreported; 361 = dynamically positioned on station, COG unreported, 362 = purposedly adrift, COG unreported, 363 = tethered, COG unreported, 364 = COG unknown = default, 365-511 reserved for future use; Dimension B = SOG, in 1 knot steps, 0-59; 60 = SOG unreported;, 61-2 047 reserved for future use.

4 = AtoN Area-Polygon. The reported position represents the starting point of a vertex, whose endpoint should be the reported position of the subsequent vertex broadcast from the same MMSI/MRN, to form a polygon area of navigational interest, i.e.

- Dimension A is the sequence number of each vertex, starting from 1, 1-8; 9-511 reserved for future use. If Dimension A = 0, then this vertex endpoint should connect to the start point of vertex 1 to form a closed polygon.

- Dimension B indicates the total number of lines in the polygon, up to 9 lines; 0‑8; 9-2 047 reserved for future use.

5 = AtoN Area-Circle. The reported position represents the centre of a circular area encompassing a navigational interest, i.e. aquaculture farm, wind farm, etc.

- Dimension A (in 1-metre steps, 0-99; 100-511 reserved for future use.) + Dimension B (in 100-metre steps, 100–204 700) = its radius.

6 = AtoN Boundary Line 1. The reported position represents the starting point of a right-hand line that bounds an area of navigational interest, i.e. (ice sheet, reported shoaling).

- Dimension A defines its orientation, clockwise from true North, in 1-degree steps: 0–359; 360–511 reserved for future use.

- Dimension B defines the length of this diagonal, in 10-metre steps, 10-20 470.

7 = AtoN Area-Sector. If AtoN Dimension Type Additional Data Flag = 1, the reported position represents the starting point of a line that is to be connected clockwise with an accompanying AtoN Dimension Type 6 with the same reported position to form a sector area of navigational interest.

- Dimension A defines its orientation, clockwise from true North, in 1-degree steps: 0–359; 360–511 reserved for future use.

- Dimension B defines the length of this line, in 10-metre steps, 10-20 470.

8 = AtoN Boundary Line 2. The reported position represents the midpoint of a line that bounds an area of navigational interest, i.e. (ice sheet, reported shoaling, water).

- Dimension A defines its orientation, clockwise from true North, in 1-degree steps: 0–359; 360–511 reserved for future use.

- Dimension B defines the length of this line, in 10-metre steps, 10-20 470.

9 = AtoN Area-Quadrilateral. If AtoN Dimension Type Additional Data Flag = 1, the reported position represents the midpoint of one side of a quadrilateral area of navigational interest, created by connecting its endpoints clockwise with the endpoints of an accompanying AtoN Dimension Type 8 or 12.

Parameter

Bits

Description

- Dimension A defines its orientation, clockwise from to true North, in 1-degree steps: 0–359; 361 (360–511 reserved for future use).

- Dimension B defines the length of this diagonal, in 10-metre steps, from 10‑20 470.

10 = AtoN Large Boundary Line 1. The reported position represents the starting point of a right-hand line that bounds an area of navigational interest, i.e. (ice sheet, reported shoaling).

- Dimension A defines its orientation, clockwise from true North, in 1-degree steps: 0–359; 360–511 reserved for future use.

- Dimension B defines the length of this diagonal, in 200-metre steps, 0-409 400.

11 = AtoN Large Area-Sector. If AtoN Dimension Type Additional Data Flag = 1, the reported position represents the starting point of line that is to be connected clockwise with an accompanying AtoN Dimension Type 10 with the same reported position to form a sector area of navigational interest.

- Dimension A defines its orientation, clockwise from true North, in 1-degree steps: 0–359; 360–511 reserved for future use.

- Dimension B defines the length of this line, in 200-metre steps, 0-409 400.

12 = AtoN Large Boundary Line 2. The reported position represents the midpoint of a line that bounds an area of navigational interest, i.e. (ice sheet, reported shoaling, water).

- Dimension A defines its orientation, clockwise from true North, in 1-degree steps: 0–359; 360–511 reserved for future use.

- Dimension B defines the length of this line, in 200-meter steps, 0-409 400.

13 = AtoN Large Area-Quadrilateral. If AtoN Dimension Type Additional Data Flag = 1, the reported position represents the midpoint of one side of a quadrilateral area of navigational interest, created by connecting its endpoints clockwise with the endpoints of an accompanying AtoN Dimension Type 12 line.

- Dimension A defines its orientation, clockwise from true North, in 1-degree steps: 0–359; 361(360–511 reserved for future use).

- Dimension B defines the length of this diagonal, in 200-meter steps, 0-409 400.

14-15 reserved for future use.

NOTE 1: Portrayal systems should only override AtoN Dimension Type data of the same AtoN Dimension Type. AtoN Dimension Type 4 and 5 require an AtoN Dimension Type 6 for their portrayal and vice versa.

NOTE 2: Use of IMO Application Specific Message Area Notice (DAC=001, FI=22) should be considered to define greater or more complex AtoN Description Areas than can be defined by this parameter.

AtoN Dimensions A

9

As defined by its AtoN Dimension Type (0 = unknown or unreported = default)

AtoN Dimension B

11

As defined by its AtoN Dimension Type (0 = unknown or unreported = default)

AtoN Dimension Type Additional Data Flag

1

To convey that this AtoN has multiple Dimension Types, i.e.

Type 1 + Type 2 (physical dimensions and swing circle of the reported AtoN)

Type 1 + Type 3 (mobile AtoN physical dimension and its vector)

Type 4 + Type 4 (to define a polygon area)

Type 6 + Type 7 (to define a sector area)

Type 8 + Type 9 or 12 (to define a quadrilateral area)

Type 10 + Type 11 (to define a sector area)

Type 12 + Type 13 (to define a quadrilateral area)

0 = This AtoN has a single AtoN Dimension Type = default.

1 = This AtoN has multiple AtoN Dimension Types.

NOTE: The report rate of Message 28 may be shortened to reduce the latency of multiple AtoN Dimension Types, particularly for AtoN Dimension Type 8 (AtoN Area-Polygon) which should broadcast all its vertices within the same frames.

AtoN Charted Status

1

Indicates whether the AtoN is charted or not.

0 = AtoN is uncharted = default
1 = AtoN charted

Parameter

Bits

Description

AtoN On-station Status

4

Indicates whether the AtoN is on-station or not.

0 = on-station = default

1 = on-station or on course (Mobile AtoN)
2 = on-station, but damaged, occulted, submerged or otherwise not properly visible
3 = off-station, a virtual AtoN reporting the intended position of this AtoN that is reporting itself off-position
4 = off-station location unknown

5 = off-station but reporting its current position
6 = off-station adrift
7 = off-station, removed or relocated
8 = on-station, as a new or temporary AtoN
9 = unmarked navigation hazard, used by a vessel to inform of an unmarked navigation hazard. The type of AtoN should be indicated as 1 = reference point. Should be accompanied by a message 14 that provides a description of the hazard, e.g. floating container.
10 = unmarked obstruction (anything that restricts, endangers, or interferes with navigation). Type of AtoN should be denoted as 1 = reference point. Should be accompanied by a message 14 that provides a description of the hazard, e.g. vessel aground.

11-15 = reserved for future use.

NOTE – AtoN off-station may accompany their report with a Message 14 stating: OFF_STATION.

AtoN Status bits

8

Reserved for the indication of the AtoN status. See IALA Recommendation R0126, The Use of the AIS in Marine AtoN Services.

00000000 = default

Spare

1

Not uses, set to 0. Reserved for future use.

Authentication Flag

1

0 = this AtoN message is not authenticated = default

1 = this AtoN message has been authenticated per IALA G1192

Number of bits

168

Occupies one slot

Code

Definition (Type of aid to navigation)

0-31

Refer to Table 72

32

Ocean Data Acquisition System (ODAS)

33

Water Sampling and/or Monitoring equipment

34

Research equipment

35

Towed Cable, Pipe or Semi-submerged Object Marker

36

Towed Vessel or Object

37

Flotsam Marker, Large (greater than 5 metres)

38

Flotsam Marker, Small (less than 5 metres)

39

Navigation hazard

40

Synthetic Target Marker

41

Protected Species Marker

42

Military Operation Target Marker

43

Dangerous Object

44

Pollution Spill Marker

Code

Definition (Type of aid to navigation)

45

Search & Rescue Datum Mark

46

Datum Mark

47

Operating Underwater (at times)

48

Underwater Operations Marker

49

Military Operation or Restricted Area

50

Dynamic Area

51-63

Reserved for future use

64-127

Reserved for regional use