Target Alert States - Sperry Marine Visionmaster FT ECDIS User Manual

ECDIS User Guide
The following criteria are used for determining the least navigationally
significant target:
1. First the system looks for targets that are 1 minute or more past
TCPA, and within this group will drop the target at the greatest
range from own ship.
2. If no active AIS targets are at least 1 minute past TCPA then the
AIS target most distant from own ship will be set to sleeping.
AIS targets can also be automatically dropped by the operator adjusting the
Autodrop range lower than the default of 10 NM. For details, refer to
`AutoDrop Targets' in the Target Display section.

Target Alert States

The following alert states apply to any AIS target in any state, (with the
exception that sleeping targets do not raise the Lost alert):
•
CPA/TCPA/BCR or Activation zone infringement
•
Lost
CPA/TCPA/BCR
or Activation zone
infringement
Lost
65900012
When an AIS target infringes the
CPA/TCPA/BCR criteria, or when
it enters an Activation zone, the
target symbol and its
heading/vector are rendered in
flashing red.
When the AIS scaled ship symbol
is used the ship outline is also
rendered in flashing red.
Activated targets that are deemed
lost are rendered with a red cross
through the AIS symbol. The
target maintains its last heading
and COG/SOG and will continue
to be dead reckoned until the lost
target alert is acknowledged.
The cross symbol flashes while
the Lost Target alert is
unacknowledged.
Note that lost AIS targets do not
generate CPA/TCPA alarms.
Targets
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