OVERVIEW: The Type 2071 ADC Mk 2 Mod 1 is a British acoustic decoy used by Royal Navy submarines to counter incoming torpedoes. It is a towed active and passive countermeasure system designed to degrade torpedo guidance and tracking.

DETAILS: Developed in the 1980s, the Type 2071 Acoustic Decoy Countermeasure (ADC) Mk 2 Mod 1 is a towed acoustic device deployed by Royal Navy submarines such as the Trafalgar-class. It operates by trailing behind the submarine on a cable and emitting controlled acoustic signals to mask the submarine’s position or to confuse active and passive torpedo seekers. The decoy is powered and programmable, capable of simulating submarine acoustic signatures or generating deceptive noise patterns. Unlike expendable decoys, it remains tethered and can be retracted after use. The system plays a key role in layered submarine self-defense, especially during high-threat anti-submarine warfare operations.

FONCTION:
Detect torpedo threats using submarine sonar.
Deploy the towed Type 2071 ADC Mk 2 Mod 1 behind the submarine.
Emit acoustic decoy signals to confuse, mislead, or divert torpedo sensors away from the host submarine.

SOURCE:
UK Ministry of Defence Underwater Defence Equipment Catalogue ; Jane’s Underwater Warfare Systems ; Royal Navy Submarine Operations Manual ; NATO Submarine Decoy Systems Briefs ; Federation of American Scientists (https://www.fas.org/man/dod-101/sys/ship/weaps/index.html)