Atlas Cover

xii EDITORIAL
THE SHOREBASED USE OF AIS
Whilst only just over two years have passed since the carriage of AIS became mandatory for ships to which Ch V of SOLAS applies,
things have moved a long way in the use of AIS ashore.
Unfettered by the presentational restrictions that have necessarily been imposed on the display of AIS in ships, the more flexible
IALA guidelines for the presentation of AIS data has resulted in more imaginative solutions being offered by equipment providers.
A significant number of VTS Centres now have AIS integrated into their traffic image displays. Some centres fuse AIS on a radar
display but a growing majority fuse AIS and radar on a traffic image display that is backed by an Electronic Chart System (ECS).
So what advantages has AIS brought to shore stations? Whilst a few centres have reported a reduction in VHF communications,
the most significant benefit has been a dramatic improvement in the accuracy of tracking and confidence in the identification of
tracks. When properly displayed, AIS can also improve the spatial awareness of VTS Operators through the presentation of
dynamic data such as heading and rate of turn, and through the accurate presentation of ship dimensions in the close passing situations
that are prevalent in the port environment (see example graphics). An AIS base station will generally see further than a
co-located radar. This can offer the benefit of advanced warning for planning and pilot allocation. It can also provide the ability
Example of AIS alone with radar video inhibited
to look into dock systems, under bridges and into channels where there would otherwise be a radar blind spot, but in such
circumstances it should be used for vessel monitoring and traffic organisation rather than navigational assistance.
To a degree AIS has been a victim of its own success. Its accelerated introduction resulted in the acceptance of the Minimum
Keyboard Display (MKD) onboard ship; its tabular presentation is of much reduced benefit to the mariner compared with a graphical
display. Although some vessels are fitted with a graphical display, the majority rely on MKD. With its poor interface for data
input, errors can be introduced that have the potential to confuse the unwary. Early teething problems were not unexpected
but the situation is now much improved.
Errors in the static message are now relatively infrequent and the introduction in some VTS Centres of comparisons between
data sources to validate AIS identity fields will help reduce this still further. Voyage related messages rely on operator update and
are more prone to errors - perhaps due to the MKD, but arguably such errors impact little on navigational safety. Errors in the
dynamic message are becoming less and less frequent with the most common being the transmission of an offset heading due to
the misalignment of the gyro input signal with the AIS transponder. Whilst anecdotal reports suggest the incidence of erroneous
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