The Triton


Virtual aids to navigation a reality


The age of virtual, electronically produced aids to navigation (ATONs) is upon us. The new AIS ATON is being tested and deployed in many areas of the world.


Unlike traditional physical aids such as buoys, beacons and lighthouses, the new AIS ATON will appear on electronic charts and ECDIS via AIS. The surprising thing, however, is that the aids may no longer be physically present in the water or on land.


The AIS ATON appears on AIS-integrated electronic navigational displays via the AIS communication system. AIS, the Automatic Identification System, is an internationally adopted communication protocol that enables a continuous exchange of automatic tracking information used for identifying and locating vessels by electronically exchanging data with other nearby vessels, AIS base stations, satellites and aids to navigation. AIS typically supplements marine radar as a method of collision avoidance.


It is a system that is becoming more widespread on vessels recreationally due to its utility, affordability and ease of use, as well as commercially due to international regulations. The International Maritime Organization (IMO) mandated the use of AIS by all vessels covered by the SOLAS convention (those over 300 tons or carrying passengers) by July 2004.

Types of AIS ATONs

There are three types of the new AIS ATON.

* Real AIS ATON: The AIS signal is transmitted from a physical aid fitted with AIS transceivers and transponders.

* Synthetic AIS ATON: The signal originates from an AIS base station in another location, but broadcasts where a physical aid exists.

* Virtual AIS ATON: The physical aid does not exist and is broadcast via AIS from another location. Unlike physical aids to navigation, the AIS ATON may appear on a display as though it was coming from a physical aid, but that physical aid is not physically there.


Depending upon the type and purpose of the ATON, official nautical charts and electronic charts will use new standardized symbols for various conditions. To see a list of these symbols, visit, search for “ATON symbols”, and click on the first link.


The AIS ATON is part of the e-navigation strategic process initiated back in 2008 by the IMO. This research and development has encompassed testing and creation of international standardization for virtual ATONs and is supported by international authorities such as IHO (International Hydrographic Organization), IALA (International Association of Marine Aids to Navigation and Lighthouse Authorities), ITU (International Telecommunications Union), IEC (International Electrotechnical Commission) and national coast guard agencies including the USCG and MCA.


These authorities have announced that testing, evaluation and transmission of AIS ATONs has begun in selected areas globally. These notices appear mostly in written marine safety notifications such as Local Notice to Mariners (LNMs) and Federal Registers. In the U.S., these tests are being done in many coastal areas. Unless mariners read the LNMs or other governmental notifications regularly, they might not have come across the reports.


Pros and cons


By far, the main benefit that governmental authorities put forward is the significantly lower cost of maintaining and repairing a virtual ATON as compared to a physical ATON. Examples of potential benefits as far as safety and security are concerned include:

* Timely “temporary” marking of a new wreck or obstruction whereby sea conditions or other factors may not permit the fast deployment of a physical aid.

* The use of virtual ATONs to “fill in gaps” in addition to existing physical ATONs or in locations where physical ATONs are challenging to deploy or maintain.

* Use for temporary operations or activities. The America’s Cup in San Francisco used virtual buoys during the races to mark the safety boundaries for spectator vessels.

* Ease and speed of deployment to replace missing physical buoys due to natural disasters. Virtual ATONs were used for approaches to New Orleans after Hurricane Katrina in 2005 when many buoys were displaced or missing.


As with all methods of navigation, redundancy is important, therefore a synthetic ATON, which is coupled with a physical ATON, is a practical combination. Virtual AIS ATONs, however, are more troubling for smaller vessel operators such as those on yachts and recreational boats. There is discussion among authorities about the possibility of replacing physical ATONs with virtual aids for more widespread use to mark shallows or obstructions, Vessel Traffic Separation Schemes, harbor approaches and restricted waterways channels, and even lighthouses.


Research and development has concentrated upon the commercial sector and has not taken into consideration the safety of smaller vessels such as yachts or recreational boats. Millions of yachts and smaller vessels do not have the technology to detect virtual ATONs and may not universally have this capability for a long time.


Of those vessels that are AIS equipped, the displays available can range from no display at all to the mandatory Class A MKD (Minimum Keyboard and Display) to full ECDIS and radar overlay.


The Class B-type AIS transceiver is designed to enable a simpler and lower cost AIS and has been developed with reduced functionality for smaller vessels. AIS Class B is usually optional and is widely used by smaller commercial craft and recreational vessels such as smaller yachts under 300 tons.


In the absence of ECDIS or radar overlay, users will not be able to fully use the AIS ATON functionality. There is also a variance of information that will be displayed by different manufacturers on ECDIS or radar equipment.


There have already been instances of corruption or “spoofing” by hackers of existing AIS ATON signals. In some tests, the AIS system has been found not to be as secure as it should be, making it possible for a terrorist to hack the signals to an AIS ATON to either harm a vessel or capture it.


Tradition disappearing

There is also a concern that navigators may spend more time looking at the electronic displays to navigate and won’t look outside, as a proper lookout should. Traditionally, prudent mariners use a buoy to visually verify set and drift or to determine the flow of currents. They often use a buoy, beacon or lighthouse as a visual range marker. Taking physical ATONs away becomes an awareness concern.


Too much reliance on electronics for navigation, especially if a vessel is not fitted with redundancy of the equipment and back-up power, could be dangerous, especially if virtual ATONs disappear when power is lost or a sole electronic navigation system crashes.


Virtual ATONs also cannot be seen on display equipment unless the vessel is in range of the AIS signal for that aid. These ATONs may not be seen on paper and electronic charts for pre-voyage planning if the vessel does not have the most recent released or updated paper or electronic charts.


With the trend toward virtual ATONs, reading the LNMs and keeping charts consistently updated becomes critical, yet many recreational boaters do not do this regularly. Generally mariners embrace advances in electronics and improvements to aids to navigation. Any technology that can improve the operation and safety of a vessel is welcome, if it has safety as its goal.


However, the safety focus surrounding virtual ATONs, if they are intended to replace all physical ATONs, is a bit blurry and should be of great concern to the yachting sector. Hopefully, the future will bring some prudent decision-making by those in control of implementation to do the right thing for the safety of vessels of all sizes.


Capt. Denise Fox has more than 20 years of experience working on yachts worldwide. As an environmental awareness advocate, she is active in the promotion of environmental practices and innovations in the yachting industry. Visit her Web site at Comments on this article are welcome at


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