Sonobuoys

Sonobuoys are expendable, self-contained underwater acoustic sensors deployed by aircraft or ships to detect submarines. Each unit combines a buoyant flotation device, hydrophones, electronics, and a telemetry system, enabling real-time or recorded acoustic data transmission to surface stations.

During operation, a platform drops or tethers the buoy, which descends to a set depth and then stabilizes. The hydrophones listen for underwater sounds. In passive mode they only listen; in active mode they emit short sonar pings and listen for echoes.

Sonobuoys are deployed in coordinated arrays to improve detection, localization, and tracking. They come in various configurations, including air-dropped, ship-launched, or submarine-launched variations, and can be short- or long-range depending on battery life and transmitter design.

Data from buoys is transmitted by radio to the pursuing platform, where it is processed to identify submarine signatures. When multiple buoys detect signals, analysts estimate range and bearing to determine a possible contact and guide further ASW actions.

Historically developed for anti-submarine warfare, sonobuoys played a central role in naval patrols since World War II and remain a core sensor in modern ASW operations, integrating with fixed or towed sonar arrays and airborne maritime patrol aircraft.

Limitations include vulnerability to environmental noise, surface conditions, and the sub’s masking of signals. Modern variants emphasize digital data links, longer endurance, and multi-sensor capabilities to improve sensitivity and reliability in complex oceans.