AIS Reporting Interval

  Including Rates Vessel's Position and Details are Transmitted


Update intervals for autonomous mode
    Reporting interval
Information
 Messages
 Frequency
Static or Voyage related
 5,24
 Every 6 min or, when data has been amended, on request.
Dynamic
See below
Safety
As required
Long Range
 27
 30 mins

    Dynamic Class A
Ships dynamic conditions
 Not Changing Course
 Changing Course
At anchor or moored and moving less than 3 knots
 3 min
 3 min
At anchor or moored and moving faster than 3 knots 10 secs 10 secs
0 to 14 knots
 10 secs
 3 1/3 secs
14 to 23 knots
 6 secs
 2 secs
Over 23 knots
 2 secs
 2 secs
If a mobile station determines it is the semaphore the reporting interval should decrease to 2 secs

    Equipment other than Class A shipborne mobile
Platform's condition
 Nominal reporting interval
Class B “SO” shipborne mobile equipment not moving faster than 2 knots 3 mins
Class B “SO” shipborne mobile equipment moving 2-14 knots 30 secs
Class B “SO” shipborne mobile equipment moving 14-23 knots 15 secs
Class B “SO” shipborne mobile equipment moving > 23 knots 5 secs
Class B “CS” shipborne mobile equipment not moving faster than 2 knots 3 mins
Class B “CS” shipborne mobile equipment moving faster than 2 knots 30 secs
Search and rescue aircraft (airborne mobile equipment) 10 secs
Aids to navigation 3 mins
AIS base station 10 secs
:A base station's reporting interval should decrease to 3 1/3 seconds after it detects one or more stations are synchronising to the base station.
SAR reporting interval's can be reduced to 2 secs in the area of SAR operations.
Static data sub-messages 24A and 24B should be transmitted every 6 mins in addition to and independant of the position report. Message 24B should be transmitted within 1 min following message 24A.

 Further Information
The above only applies when the AIS equipment is operating in autonomous mode, if operating in assigned mode, the reporting interval is set by the base station using message 23.
Message 23 allows the base station to set the reporting interval anywhere between 2 secs to 10 minutes and can command the AIS transponder to be "quiet" for 1 to 15 minutes.
Each AIS channel reports at half the nominal reporting rate.
Hence an AIS receiver monitoring only one channel (eg scanner) will receive static information from a vessel every 12 mins.
An AIS receiver switching between channels (eg the NASA or SR161) can easily miss a transmission on one channel and miss the next transmission on the other channel - this could happen a few times in succession resulting in a considerable delay before the ships name is actually received.
Class A, Base stations and SAR equipment can interrogate other mobile equipment for "ad hoc" position and static data reports using message 15 (Class B equipment cannot do this).