Sonar technician (abbreviated as ST) is a United States Navy occupational rating. STs are responsible for underwater surveillance. They assist in safe navigation and aid in search, rescue and attack operations. They operate and repair sonar equipment. STs track underwater threats and send tracks to fire control (antisubmarine warfare controlling station) operator (ASWCS) for further evaluation and or destruction. Sonar technicians are separated into two categories, STG (sonar technician surface) who are on surface ships and STS (sonar technician submarine) who operate on submarines.