Operation Manual

User Manual

giving the skipper or navigator a visual interpretation of the data of nearby vessels.

This improves safety, and specifically for collision avoidance reasons.

5.7.1 AIS SYSTEM DEFINITIONS

• Target

It is a vessel equipped with AIS. Information about the targets is being re-

ceived by AIS Receiver and displayed on the screen.

• CPA

Closest Point of Approach is the closest distance that will be achieved be-

tween your vessel and the tracked target, based on your vessel’s speed and

direction and the target’s speed and direction.

• CPA Limit

This is the distance from your vessel that a target may reach before a target is

deemed a threat.

• CPA Alarm

Occurs if CPA is less or equal to CPA Limit. This test is done for active

targets only.

• TCPA

Time to closest Point of Approach is the time remaining until the CPA will

occur.

• TCPA Limit

This is the time remaining before the CPA is reached.

• TCPA Alarm

Occurs if TCPA is less or equal to TCPA Limit. This test is done for active

targets only and if CPA value is less or equal to CPA Limit.

• Radio Call Sign

International call sign assigned to vessel, often used on voice radio.

• Name

Name of ship, 20 characters.

• MMSI

Maritime Mobile Service Identity.

• MMSI number

A unique 9 digit number that is assigned to a DSC radio station. It primarily

registers the boat information in the U.S. Coast Guard’s national distress

database for use in emergency situations.

• Active Target

Target located within the Activation Range. Active target is represented by

oriented triangle with COG and Heading vectors. Rate of turn may also be

displayed.