They assist in safe navigation and aid in search, rescue and attack operations.

as "ping jockeys" on board surface vessels, after the sound of active sonar.

Sonar technicians, surface fleet (manipulate, control, evaluate, and interpret data) surface sonar, Towed array, and other oceanographic systems; operate surface ship underwater fire control systems (with associated equipment) for the solution of antisubmarine warfare problems, operate underwater communications, torpedo countermeasure equipment, depth finders for navigation, collect and disseminate bathythermograph data, calculate optimum performance; perform organizational and intermediate maintenance on surface sonar and allied equipment.

During battle stations, sonarmen track targets, passing bearing information to fire control to refine speed, range and course.

The majority of the sonar used aboard submarines is passive, since active emissions give away a vessel's position.