Type SSQ 981 Sonobuoy

The SSQ 981 is a passive sonobuoy used in anti-submarine operations. A passive sonobuoy listens for underwater noises emitted from submarines, such as machinery and aims to eliminate background noises found in the sea such as wildlife and waves.

The SSQ 981 is from a family of passive sonobuoys developed in the 1980s. Once dropped from an aircraft, it descends to a pre-set depth where it deploys a number of underwater microphones (hydrophones) which can detect a submarine’s range and bearing. Data is transmitted to a circling aircraft via a float and transmitter which remains on the surface.