How do sonobuoys help aircraft locate submarines?

Sonobuoys are essential tools for aircraft to detect submarines in the open ocean, where ship-based sensors cannot cover every area. These devices are floating buoys equipped with sonar sensors and radio transmitters.12

When deployed, sonobuoys function using two primary acoustic methods:

• Passive Detection: The buoy acts as a listening sensor, picking up noise generated by the submarine, such as propeller sounds.34
• Active Detection: The buoy acts as an acoustic projector, sending out sound waves that reflect off the submarine's hull, allowing the system to determine the target's range, bearing, and motion.3

Once the sonobuoy detects these acoustic signals, it transmits the data via radio to patrolling aircraft. The aircraft then receive and analyze these signals to track the submarine's location. Because sonar range is limited by factors like water temperature and background noise, aircraft often deploy multiple sonobuoys to effectively monitor a broad area.124