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Automatic Identification System (AIS)
Primary Mission Areas:
Services & Reporting:
Maritime Information:
AIS MESSAGES

The following is a listing of current AIS Messages, their priorities, and their access schemes used to transmit data. You may download this sheet in a printer friendly PDF format.  You may also download ITU‐R M.1371‐4 Message Nr. - Data Broadcasted From Each AIS Station Type.

Message ID

Name

Description

Priority

Access scheme

Communication state M/B

1

Position report

Scheduled position report; Class A shipborne mobile equipment

1

SOTDMA, RATDMA, ITDMA

SOTDMA

M

2

Position report

Assigned scheduled position report; Class A shipborne mobile equipment

1

SOTDMA

SOTDMA

M

3

Position report

Special position report, response to interrogation; Class A shipborne mobile equipment

1

RATDMA

ITDMA

M

4

Base station report

Position, UTC, date and current slot number of base station

1

FATDMA, RATDMA

SOTDMA

B

5

Static and voyage related data

Scheduled static and voyage related vessel data report; Class A shipborne mobile equipment

4

RATDMA, ITDMA

N/A

M

6

Binary addressed message

Binary data for addressed communication

4

RATDMA, FATDMA, ITDMA

N/A

M/B

7

Binary acknowledgement

Acknowledgement of received addressed binary data

1

RATDMA, FATDMA, ITDMA

N/A

M/B

8

Binary broadcast message

Binary data for broadcast communication

4

RATDMA, FATDMA, ITDMA

N/A

M/B

9

Standard SAR aircraft position report

Position report for airborne stations involved in SAR operations only

1

SOTDMA, RATDMA, ITDMA

SOTDMA ITDMA

M

10

UTC/date inquiry

Request UTC and date

3

RATDMA, FATDMA, ITDMA

N/A

M/B

11

UTC/date response

Current UTC and date if available

3

RATDMA, ITDMA

SOTDMA

M

12

Addressed safety related message

Safety related data for addressed communication

2

RATDMA, FATDMA, ITDMA

N/A

M/B

13

Safety related acknowledgement

Acknowledgement of received addressed safety related message

1

RATDMA, FATDMA, ITDMA

N/A

M/B

14

Safety related broadcast message

Safety related data for broadcast communication

2

RATDMA, FATDMA, ITDMA

N/A

M/B

15

Interrogation

Request for a specific message type can result in multiple responses from one or several stations

3

RATDMA, FATDMA, ITDMA

N/A

M/B

16

Assignment mode command

Assignment of a specific report behaviour by competent authority using a Base station

1

RATDMA, FATDMA

N/A

B

17

DGNSS broadcast binary message

DGNSS corrections provided by a base station

2

FATDMA, RATDMA

N/A

B

18

Standard Class B equipment position report

Standard position report for Class B shipborne mobile equipment to be used instead of Messages 1, 2, 3

1

SOTDMA, ITDMA, CSTDMA

SOTDMA, ITDMA

M

19

Extended Class B equipment position report

No longer required. Extended position report for Class B shipborne mobile equipment; contains additional
static information

1

ITDMA

N/A

M

20

Data link management message

Reserve slots for Base station(s)

1

FATDMA, RATDMA

N/A

B

21

Aids-to-navigation report

Position and status report for aids-to-navigation

1

FATDMA, RATDMA

N/A

M/B

22

Channel management

Management of channels and transceiver modes by a Base station

1

FATDMA, RATDMA

N/A

B

23

Group assignment command

Assignment of a specific report behaviour by competent authority using a Base station to a specific group of mobiles

1

FATDMA, RATDMA

N/A

B

24

Static data report

Additional data assigned to an MMSI

Part A: Name
Part B: Static Data

4

RATDMA, ITDMA, CSTDMA, FATDMA

N/A

M/B

25

Single slot binary message

Short unscheduled binary data transmission Broadcast or addressed

4

RATDMA, ITDMA, CSTDMA, FATDMA

N/A

M/B

26

Multiple slot binary message with Communications State

Scheduled binary data transmission Broadcast or addressed

4

SOTDMA, RATDMA, ITDMA, FATDMA

SOTDMA,
ITDMA

M/B

27 Position report for long range applications Class A and Class B "SO" shipborne mobile equipment outside base station coverage 1
MSSA

N/A

M
28-63 Undefined; Reserved for future use
N/A

N/A

N/A

N/A

M

(Source: ITU-R M.1371-5)
Terms:
  • M/B: M: transmitted by mobile station
  • B: transmitted by Base station.
  • FATDMA Fixed Access Time Division Multiple Access
  • ITDMA Incremental time division multiple access
  • SOTDMA Self organizing time division multiple access
  • RATDMA Random access time division multiple access
  • MSSA Multi-channel Slot Selection Access