User's Manual Part 2

Operator Manual
3−14
3748DOC020102 Edition: 14.JAN.2005
3.4 Automatic Radar Plotting Aid (ARPA)
The purpose of an Automatic Radar Plotting Aid (ARPA) is to interpret radar
information continuously and to display the results so that watch officers may
quickly assess and react to potential danger. The performance specfication of
the International Maritim Organization (IMO) requires the ARPA plotting reliability
to be as good as manual plotting techniques. The NSC meets and exceeds
these minimum requirements to provide a greater margin of safetey.
The first requirement of safetey is to maintan surveillance of traffic and
navigation harzards. The ARPA will plot up to 70 manually acquired (Plot)
targets.
For any targets being plotted, the ARPA continuously displays vectors indicating
speed and course. Based on preset conditions the ARPA determines if the
possibility for collision exists.
When a potentially dangerous target is detected, warnings are given and
information detailed on the target is displayed.
If the watch officer determines that an avoidance maneuver is required, the
ARPA trial maneuver mode can assist in the planning. When a maneuver is
actually made, the ARPA continuously displays the effect on all plotted targets
during and after the course change.