Conditions For Deciding Ais Target To Be Lost - JRC JMA-5204 Instruction Manual

5.3.9 Conditions for Deciding AIS Target to be Lost

About a lost target
When the data of an AIS target cannot be received for a specified time, the target is decided to be lost and the
target data is deleted. As shown in the table below, the time until target data is deleted varies depending on the
class of receive data and the target status.
Deciding AIS Target to be Lost
Vessel below 3 knots and it is now at anchor or on the berth
(Class B: below 2 knots)
Vessel of 3 knots or more and it is now at anchor or on the berth
Vessel of 0 to 14 knots (Class B: 2 to 14 knots)
Vessel of 0 to 14 knots and it is now changing the course
Vessel of 14 to 23 knots
Vessel of 14 to 23 knots and it is now changing the course
Vessel of 23 knots or more
Vessel of 23 knots or more and it is now changing the course
SAR (Search and Rescue)
ATON (Aid to Navigation)
Base station
Reference:
If Active targets (including dangerous ships) and numerically displayed targets is lost, a lost target alarm is
issued, and the symbol changes to a lost target symbol. The system continues to display the symbol where it
received the last data. If the ALARM ACK switch is pressed, the symbol is cleared.
Target status
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5.3 AIS OPERATION
Time until data deletion
SOLAS ship SOLAS ship
(Class A) (Class B)
18 min 18 min
60 sec 18 min
60 sec 180 sec
60 sec 180 sec
36 sec 180 sec
36 sec 180 sec
30 sec 180 sec
30 sec 180 sec
60 sec 60 sec
18 min 18 min
60 sec 60 sec
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