The U.S. Navy, in a break with traditional submarine detection, is working to replace sonar and magnetic detection with radar. The AN/APS-154 Advanced Airborne Sensor (AAS) will spot the invisible wakes left by submarines underwater, telltale clues that something large is lurking beneath the waves. The AAS will be carried by the P-8 Poseidon aircraft (shown above), which can then engage submarines with air-dropped anti-submarine torpedoes.
According to Forbes, the downward-mounted pod features an advanced electronically scanning array (AESA) radar. Unlike traditional dish radars that use one large, powerful radar module, AESA radars use many smaller modules. These modules can collectively operate over multiple frequencies, which means they can overcome jamming or broaden or focus their field of detection, especially against small objects and those invisible to the human eye.
One such object is the wake created by a submerged submarine on the surface of the ocean. Subs create wakes as they displace water in their path, which are barely visible on the surface. A radar like the AAS can pick out these wakes from the pattern of regular ocean waves, betraying a submarine’s location.
Once a submarine is detected, a P-8 can drop a Mk. 54 lightweight anti-submarine torpedo to give chase. The Mk. 54, delivered by parachute, will enter the water, turn on its onboard sonar system, and start searching for the enemy sub. When the torpedo finds the sub, it moves to intercept, detonating a 100-pound warhead against the submarine’s hull.
The AAS appears likely to replace older submarine detection systems. Aircraft like the Navy’s P-3C Orion would often drop sonobuoys in waters suspected of harboring enemy submarines. The sonobuoys, pinging away with sonar, transmit their data to the circling P-3C. Another system, Magnetic Anomaly Detection, detects the disturbance in Earth’s magnetic field created by a large, steel-hulled submarine.
The P-8 Poseidon maritime patrol aircraft is fairly new in U.S. Navy service. Unlike older planes, it retains the ability to drop sonobuoys, but wasn’t built with a telltale MAD boom, suggesting the Navy is confident radar submarine detection will work.
Picture: US Navy