Surveillance Towed Array Sensor System The AN / UQQ - 2 Surveillance Towed Array Sensor System ( SURTASS ) , colloquially referred to as the ship ' s ' Tail ' , is a towed array sonar system of the United States Navy . SURTASS Twin - Line consists of either the long passive SURTASS array or the Twin - line array consisting of two shorter passive arrays towed side by side . The Twin - line Engineering Development Model was installed on USNS " Assertive " , and the first production model was installed on USNS " Bold " . Both ships are no longer serving as SURTASS units . , SURTASS was deployed on the four " Victorious " - class vessels and the ( a small - waterplane - area twin hull ( SWATH ) vessel ) . History . SURTASS began as development program in 1973 using the new research vessel " Moana Wave " . In 1980 SURTASS passed OPEVAL . The new " Stalwart " - class ocean surveillance ships had the first contract awarded on 26 September 1980 and were similar to the prototype ship , the " Moana Wave " . Initially the SURTASS system were passive , receive only sonar systems . The array was towed miles behind the ships and were designed for long range detection of submarines . As the passive systems were being deployed , an active adjunct known as the SURTASS Low Frequency Active ( LFA ) systems was designed for long range detection . The active system must be used in conjunction with the passive received system . The active component transmits an audio signal between 100 Hz and 500 Hz from an array suspended below the ship while the passive SURTASS array is towed miles behind to receive the signal after it had reflected off the submarine . The active LFA system is an updated version of the fixed low frequency surveillance system known as Project ARTEMIS . Although the Navy took steps to mitigate the environmental damage , environmental non - governmental organizations ( NGOs ) urged the Navy to prepare a public environmental impact statement . In 1996 the Navy published a notice of intent to prepare an environmental impact statement . The Navy has spent over $ 16 million on scientific research on the effects on marine mammals and mitigation systems as well as the development of an Environmental Impact Statement . Description . SURTASS LFA is a long - range , all - weather , sonar system with both passive and active components , operating in the low frequency ( LF ) band ( 100 – 500 hertz [ Hz ] ) . USNS " Impeccable " has the original LFA system , weighing 155 tonnes ; the 64 - tonne Compact LFA derivative was developed for the smaller " Victorious " class . CLFA was installed on " Able " in 2008 , on " Effective " in 2011 and " Victorious " in 2012 ; no further installations are planned . The active system component , LFA , is an adjunct to the passive detection system , SURTASS , and is planned for use when passive system performance proves inadequate . LFA is a set of acoustic transmitting source elements suspended by cable from underneath a ship . These elements , called projectors , are devices that produce the active sound pulse , or ping . The projectors transform electrical energy to mechanical energy that set up vibrations or pressure disturbances within the water to produce a ping . The characteristics and operating features of LFA are : The passive , or listening , part of the system is SURTASS , which detects returning echoes from submerged objects , such as submarines , through the use of hydrophones . These devices transform mechanical energy ( received acoustic sound wave ) to an electrical signal that can be analyzed by the signal processing system of the sonar . The SURTASS hydrophones are mounted on a horizontal receive array that is towed behind the vessel . The array length is 1 , 500 m ( 4 , 900 ft ) with an operational depth of 150 to 460 m ( 500 to 1 , 500 ft ) . The SURTASS LFA ship must maintain a minimum speed of approximately through the water in order to tow the hydrophone array in the horizontal plane . The return signals or echoes , which are usually below background or ambient noise level , are then processed and evaluated to identify and classify potential underwater targets .