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

Data sheet of what is broadcast by each station. The following is a listing of current AIS Messages, their priorities, and their access schemes used to transmit data.

Message ID Name Description Priority Access scheme Communi-cation state M/B

1

Position report

Scheduled position report; (Class A shipborne mobile equipment)

1

SOTDMA, RATDMA, ITDMA(1)

SOTDMA

M

2

Position report

Assigned scheduled position report; (Class A shipborne mobile equipment)

1

SOTDMA(9)

SOTDMA

M

3

Position report

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

1

RATDMA(1)

ITDMA

M

4

Base station report

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

1

FATDMA(3) (7), RATDMA(2)

SOTDMA

B

5

Static and voyage related data

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

4(5)

RATDMA, ITDMA(2)

N/A

M

6

Binary addressed message

Binary data for addressed communication

4

RATDMA(10), FATDMA, ITDMA(2)

N/A

M/B

7

Binary acknowledgement

Acknowledgement of received addressed binary data

1

RATDMA, FATDMA, ITDMA(2)

N/A

M/B

8

Binary broadcast message

Binary data for broadcast communication

4

RATDMA(10), FATDMA, ITDMA(2)

N/A

M/B

9

Standard SAR aircraft position report

Position report for airborne stations involved in SAR operations, only

1

SOTDMA, RATDMA, ITDMA(1)

SOTDMA ITDMA

M

10

UTC/date inquiry

Request UTC and date

3

RATDMA, FATDMA, ITDMA(2)

N/A

M/B

11

UTC/date response

Current UTC and date if available

3

RATDMA, ITDMA(2)

SOTDMA

M

12

Addressed safety related message

Safety related data for addressed communication

2

RATDMA(10), FATDMA, ITDMA(2)

N/A

M/B

13

Safety related acknowledgement

Acknowledgement of received addressed safety related message

1

RATDMA, FATDMA, ITDMA(2)

N/A

M/B

14

Safety related broadcast message

Safety related data for broadcast communication

2

RATDMA(10), FATDMA, ITDMA(2)

N/A

M/B

15

Interrogation

Request for a specific message type (can result in multiple responses from one or several stations)(4)

3

RATDMA, FATDMA, ITDMA(2)

N/A

M/B

16

Assignment mode command

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

1

RATDMA, FATDMA(2)

N/A

B

17

DGNSS broadcast binary message

DGNSS corrections provided by a base station

2

FATDMA(3), RATDMA(2)

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(8)

1

SOTDMA, ITDMA(1),

CSTDMA

SOTDMA, ITDMA

M

19

Extended Class B equipment position report

Extended position report for class B shipborne mobile equipment; contains additional
static information
(8)

1

ITDMA

N/A

M

20

Data link management message

Reserve slots for Base station(s)

1

FATDMA(3), RATDMA

N/A

B

21

Aids-to-navigation report

Position and status report for aids-to-navigation

1

FATDMA(3), RATDMA(2)

N/A

M/B

22

Channel management(6)

Management of channels and transceiver modes by a Base station

1

FATDMA(3), RATDMA(2)

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

SOTDMA,
ITDMA

M/B

27
Position report for long range applications

Scheduled
position report; (Class A shipborne mobile equipment outside base station coverage)

1

RATDMA

N/A

M
28-63
Undefined; Reserved for future use

N/A

N/A

N/A

N/A

M
(Source: ITU-R M.1371)

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