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United States Coast Guard

Visual Aids to Navigation Division


The Visual Aids to Navigation Division is responsible for establishing requirements and policy, providing program level guidance, and coordinating processes, platforms, and personnel necessary to establish, maintain, and operate the United States Visual Aids to Navigation System (USATONS). 

The USATONS is a critical component of the United States Marine Transportation System (MTS) for reducing transit risks and maintaining capacity.  To ensure MTS user confidence in the USATONS, Aid Availability Rates (AAR) are monitored and measured against established AAR objectives.

Aid Availability is the probability that an Aid to Navigation (ATON) or system is performing its specified function at any random chosen time.  It is a measure of the heath of an ATON system.  The U. S. Coast Guard has established three AAR objectives based on the critical nature of ATON within a given waterway.  The AAR objectives for the three categories are:  99.8% for Category I ATON, 99% for Category II ATON, and 97% for Category III ATON.  The overall weighted AAR for the USATONS is 97.5%.

USCGC GENTIAN breaking ice along the Delaware River in 1945

Mariner Resources: Public Resources:
Light List Laws & Regulations
Local Notice to Mariners Waterways Management Branches
Aid Discrepancy Report Boating Courses
Navigation Rules Frequently Asked Questions
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Last Modified 9/27/2012