14-1
14. AIS TARGET FUNCTIONS
14.1 Introduction
An AIS transponder can be connected to the ECDIS to display AIS targets received
from an AIS transponder. The ECDIS can store up to 2,000 AIS targets in its storage
buffer. When this buffer becomes full of AIS targets, Alert 533 “AIS Target Capacity
100%” is generated to alert you that the storage buffer is full. The storage buffer con-
tains automatic dead reckoning for all AIS targets, which is based on reported Speed
Over Ground (SOG), Course Over Ground (COG), Rate Of Turn (ROT) and heading.
The storage buffer also contains calculation of range, bearing, CPA, TCPA, etc. The
CPA and TCPA limits set for dangerous targets are common for TT and AIS targets.
This ECDIS can activate 500 AIS targets. The Alert 535 “AIS Target Activate 100%”
appears when 500 AIS targets are activated.
The frequency for update of AIS transponder-sent data depends on speed and course
of tracked AIS target. The table below shows the IMO standardized reporting rates for
the AIS transponder. Based on the table below, the ECDIS defines which AIS targets
are in tracking or lost. When you acknowledge the lost target alert, the AIS symbol is
removed from the ECDIS display.
An AIS transponder "sees" all ships fitted with an AIS transponder belonging to either
Class A or Class B.
Additionally the AIS transponder receives messages other than messages from ships:
Type of Ship
IMO
nominal reporting
interval
Class A: Navigation status is “anchor” or “not under command” or “moored”
or “aground”, and SOG < 3 kn
3 min
Class A: Navigation status is “anchor” or “not under command” or “moored”
or “aground”, and SOG t
3kn
10 s
Class A: 0kn d
SOG < 14kn 10 s
Class A: 14kn d
SOG d 23kn 6 s
Class A: SOG > 23kn 2 s
Class B: “CS” SOG < 2kn 3 min
Class B: “CS” SOG t
2kn 30 s
Class B: “SO” 0 kn d SOG < 2kn 3 min
Class B: “SO” 2 kn d SOG < 14kn 30 s
Class B: “SO” 14 kn d SOG d
23kn 15 s
Class B: “SO” SOG > 23kn 5 s
Class A and Class B: no SOG available N/A
AIS SAR aircraft 10 s
AIS aid to navigation 3 min
AIS base station 10 s
AIS search and rescue transponder N/A
• AIS Base station • AIS on airborne SAR craft
• AIS on ATON (AIS aid to navigation)
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