By Mass Communication Specialist 1st Class Brandan W. The National Marine Fisheries Services issued a final rule Aug. 16 that allows the Navy to continue operating Surveillance Towed Array Sensor System Low Frequency Active (SURTASS LFA) sonar in the western Pacific Ocean for the next five years, subject to a yearly authorization renewal. SURTASS LFA consists of two separate components. The LFA portion of the system is suspended vertically below the ship and transmits low-frequency sound energy into the water. SURTASS, the passive portion of the system, is towed behind the ship and is made up of a series of underwater microphones that detect natural and man-made sound energy in the water. This allows underwater objects, such as submarines, to be detected.