Navigation Center
United States Coast Guard
U.S. Department of Homeland Security

AIS Messages

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 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