TB-37(U) Multi-Function Towed Array

The TB-37(U) Multi-Function Towed Array (MFTA) sonar represents one of the most advanced undersea warfare technologies currently deployed by the United States Navy. Designed as a critical component of the AN/SQQ-89 Undersea Warfare system, it provides surface ships with the ability to detect, locate, and track submarines across a wide range of ocean environments. Its long, slender three-inch diameter array is towed behind vessels such as Arleigh Burke-class destroyers, Ticonderoga-class cruisers, and Zumwalt-class destroyers, ensuring that the sensors are positioned far from the ship’s own noise, which greatly enhances detection performance.

Photo: l3harris.com

The system’s dual capability to operate in both passive and active modes makes it highly versatile in modern naval operations. In passive mode, the TB-37(U) listens for the faint acoustic signatures of submarines, which can include the sound of propellers, machinery, or even subtle hydrodynamic disturbances. In active mode, the array emits carefully calibrated sound pulses, or “pings,” and then analyzes the returning echoes to determine the position and movement of underwater threats, a function particularly useful against submarines employing advanced quieting technologies.

One of the defining strengths of the TB-37(U) is its ability to provide long-range detection and tracking of submarines, even those designed to be exceptionally quiet. Modern submarines are built with advanced noise-reduction features, making them difficult to detect with older sonar systems. The TB-37(U), however, leverages its sophisticated hydrophone array and advanced signal processing to identify and track these elusive targets, giving naval commanders a decisive advantage in contested waters.

The system is fully integrated into the AN/SQQ-89 Undersea Warfare Combat System, which combines multiple sensors and weapons into a single coordinated network. This integration allows the TB-37(U) to work seamlessly with hull-mounted sonars, sonobuoys, and other detection systems, creating a layered defense against undersea threats. By feeding its data into the larger combat system, the TB-37(U) ensures that surface ships can not only detect submarines but also classify and engage them with precision.

The towed array technology itself is a major factor in the system’s effectiveness. By trailing the hydrophones behind the ship on a long cable, the sonar array is able to escape the interference caused by the vessel’s own engines, propellers, and onboard machinery. This positioning dramatically improves the clarity of the acoustic environment, allowing the system to pick up faint signals that would otherwise be lost in background noise. The result is a sonar system capable of detecting submarines at ranges that provide commanders with valuable time to respond.

Another important feature of the TB-37(U) is its ability to operate at different depths within the water column. Ocean conditions such as temperature, salinity, and pressure create layers that can bend or reflect sound waves, often allowing submarines to hide within them. By adjusting the depth of the towed array, operators can position the sensors in the most favorable acoustic layer, ensuring that submarines attempting to exploit these natural hiding places are still detected and tracked.

The TB-37(U) is deployed across several of the U.S. Navy’s most important surface combatants. Arleigh Burke-class destroyers, which form the backbone of the Navy’s surface fleet, rely on the system to extend their anti-submarine warfare capabilities. Ticonderoga-class cruisers, with their multi-mission roles, also benefit from the enhanced undersea awareness provided by the TB-37(U). The futuristic Zumwalt-class destroyers, designed with stealth and advanced combat systems, integrate the TB-37(U) to ensure they remain effective in undersea warfare. Additionally, the Littoral Combat Ship, which is optimized for operations in coastal waters, can also employ the system to counter submarine threats in shallow and complex environments.

The development and production of the TB-37(U) involve collaboration between several major defense contractors. L3Harris and Lockheed Martin serve as the primary developers and manufacturers, bringing together their expertise in sonar technology, systems integration, and naval warfare solutions. L-3 Chesapeake Sciences also contributes to the design and development of key components, ensuring that the system remains at the cutting edge of undersea detection technology. This collaboration reflects the complexity of modern sonar systems, which require advanced engineering, software development, and acoustic science to achieve their performance goals.