United States Coast Guard

Visual Aids to Navigation Division

COMMANDANT (CG-NAV-1)

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%.