AIS Class A Ship Static and Voyage Related Data (Message 5)

In addition, the Class A AIS unit broadcasts the following information every 6 minutes. Should only be used by Class A shipborne and SAR aircraft AIS stations when reporting static or voyage related data:

Parameter	Bits	Description
Message ID	6	Identifier for this Message
Repeat indicator	2	Used by the repeater to indicate how many times a message has been repeated. Refer to §?4.6.1, Annex 2; 0-3; 0 = default; 3 = do not repeat any more
User ID	30	MMSI number
AIS version indicator	2	0 = station compliant with Recommendation ITU-R M.1371-1 1 = station compliant with Recommendation ITU-R M.1371-3 (or later) 2 = station compliant with Recommendation ITU-R M.1371-5 (or later) 3 = station compliant with future editions
IMO number	30	0 = not available = default – Not applicable to SAR aircraft 0000000001-0000999999 not used 0001000000-0009999999 = valid IMO number; 0010000000-1073741823 = official flag state number.
Call sign	42	7?=?6 bit ASCII characters, @@@@@@@ = not available = default Craft associated with a parent vessel, should use “A” followed by the last 6 digits of the MMSI of the parent vessel. Examples of these craft include towed vessels, rescue boats, tenders, lifeboats and liferafts.
Name	120	Maximum 20 characters 6 bit ASCII "@@@@@@@@@@@@@@@@@@@@" = not available = default The Name should be as shown on the station radio license. For SAR aircraft, it should be set to “SAR AIRCRAFT NNNNNNN” where NNNNNNN equals the aircraft registration number.
Type of ship and cargo type	8	0 = not available or no ship = default 1-99 = as defined below 100-199 = reserved, for regional use 200-255 = reserved, for future use Not applicable to SAR aircraft
Overall dimension/ reference for position	30	Reference point for reported position. Also indicates the dimension of ship (m) (see below) For SAR aircraft, the use of this field may be decided by the responsible administration. If used it should indicate the maximum dimensions of the craft. As default should A = B = C = D be set to “0”
Type of electronic position fixing device	4	0 = undefined (default) 1 = GPS 2 = GLONASS 3 = combined GPS/GLONASS 4 = Loran-C 5 = Chayka 6 = integrated navigation system 7 = surveyed 8 = Galileo, 9-14 = not used 15 = internal GNSS
ETA	20	Estimated time of arrival; MMDDHHMM UTC Bits 19-16: month; 1-12; 0 = not available = default Bits 15-11: day; 1-31; 0 = not available = default Bits 10-6: hour; 0-23; 24 = not available = default Bits 5-0: minute; 0-59; 60 = not available = default For SAR aircraft, the use of this field may be decided by the responsible administration
Maximum present static draught	8	In 1/10 m, 255 = draught 25.5 m or greater, 0 = not available = default; in accordance with IMO Resolution A.851 Not applicable to SAR aircraft, should be set to 0
Destination	120	Maximum 20 characters using 6-bit ASCII; @@@@@@@@@@@@@@@@@@@@ = not available For SAR aircraft, the use of this field may be decided by the responsible administration
DTE	1	Data terminal equipment (DTE) ready (0 = available, 1 = not available = default)
Spare	1	Spare. Not used. Should be set to zero. Reserved for future use.
Number of bits	424	Occupies 2 slots

Type of ship

*** (Vessels operating in U.S. waters should encode their ship type as
denoted in the USCG AIS Encoding Guide) ***

Identifier No.	Special craft
Identifiers To Be Used By Ships To Report Their Type
50	Pilot vessel
51	Search and rescue vessels
52	Tugs
53	Port tenders
54	Vessels with anti-pollution facilities or equipment
55	Law enforcement vessels
56	Spare - for assignments to local vessels
57	Spare - for assignments to local vessels
58	Medical transports (as defined in the 1949 Geneva Conventions and Additional Protocols)
59	Ships and aircraft of States not parties to an armed conflict

Identifiers to be used by ships to report their type

Other ships

First digit(1)

Second digit(1)

First digit(1)

Second digit(1)

1 - Reserved for future use

0 - All ships of this type

0 - Fishing

2 - WIG

1 - Carrying DG, HS, or MP, IMO hazard or pollutant category X

1 - Towing

3 - See right column

2 - Carrying DG, HS, or MP, IMO hazard or pollutant category Y

3 - Vessel

2 - Towing and length of the tow exceeds 200 m or breadth exceeds 25 m

4 - HSC

3 - Carrying DG, HS, or MP, IMO hazard or pollutant category Z

3 - Engaged in dredging or underwater operations

5 - See above

4 - Carrying DG, HS, or MP, IMO hazard or pollutant category OS

4 - Engaged in diving operations

5 - Reserved for future use

5 - Engaged in military operations

6 - Passenger ships

6 - Reserved for future use

6 - Sailing

7 - Cargo ships

7 - Reserved for future use

7 - Pleasure craft

8 - Tanker(s)

8 - Reserved for future use

9 - Other types of ship

9 - No additional information

9 - Reserved for future use

(1) The identifier should be constructed by selecting the appropriate first and second digits.

The second digits 1, 2, 3 and 4 reflecting categories X, Y, Z and OS formerly were categories A, B, C and D.

Reference point for reported position and overall dimensions of ship

reported position and overall dimensions of ship

(Source: International Telecommunications Union Recommendation ITU-R M.1371-5)

External Position Fixing System (EPFS)

An EPFS can be any navigation system, receiver or integrated navigation system (INS), having an IEC 61162 interface. On a Safety of Life at Sea (SOLAS) Convention ship the navigation system must meet IMO performance standards and be certified. In practice, most EPFS systems are currently GPS, and some GPS devices provide a dead reckoning (estimated position) mode. The type of EPFS used is derived from IEC 61162-1 sentence GLL, VTG, GDT, and ROT from the sensor input and is transmitted by the four bit Class A Message 5 or Class B Message 19. It is understood that the overwhelming majority of EPFS sensors interfaced with AIS are GPS. If an EPFS device is not connected to the AIS, the internal AIS GPS is used to provide position. The table describes fallback conditions and priority for how these positions sensors are used by AIS.

Position sensor fallback conditions

(Source International Electrotechnical Commission IEC 61993-2)