Anti-submarine Warfare (ASW)

Anti-submarine Warfare (ASW) is aimed at locating, tracking and damaging/destroying a submarine. ASW measures can also deter a hostile submarine from entering prohibited zones.

ASW can be carried from sub-surface, surface and aerial platforms. Here the focus will be on aerial platforms to include fixed wing, rotary wing and unmanned aerial platforms.

Detection of submarine is done primarily by a Sonobuoy and Magnetic Anomaly Detector (MAD) - refers specifically to magnetometers used by military forces to detect submarines by observing the change in the magnetic field. The weapon of choice is a torpedo apart from depth charges and mines - all that can be launched from air.

Fixed Wing Aircraft

P-8I. P8’s Indian variant is named P-8I. It can carry out long range Maritime surveillance, ASW, Anti Surface warfare and Search and Rescue. Indian Navy has nine aircraft and three are expected to join the fleet soon. Its speed is 490 knots (789 km/h), range is 1200+ nautical miles with 4 hours on the station (2,222 km) and ceiling is 12,496m. P-8I features an international version of the Raytheon’s APY-10 radar, APS-143C(V)3 multimode radar with MAD. The internal weapons bay can house Mark 54 torpedoes, depth charges and free-fall bombs. The under-wing hardpoints can be armed with air-to-surface missiles. For ASW India has purchased AGM-84L Harpoon Block II missiles and Mk 54 All-Up-Round Lightweight torpedoes. For carrying out ASW High Altitude Anti-Submarine Warfare Weapon Capability (HAAWC), Air Launch Accessory (ALA) is required which turns the Mark 54 torpedo into a glide bomb for deploying from up to 9,100 m. The Harpoon Block II carries a 226 kg blast / fragmentation warhead and can be fired against land and sea targets. Indian Navy participated in ASW exercise Sea Dragon 2021 along with QUAD nations and Canada in Guam, flagging the importance of ASW.

The primary missions of the ‘Romeo’ helicopter are antisubmarine warfare and antisurface warfare. Secondary missions include search and rescue, logistics support, personnel transport, and medical evacuation.

C295. Derived from CN-235, propellerdriven tactical transport aircraft saw the twin-turboprop system revised into the C295 with a lengthened fuselage. CASA has since fallen under the EADS brand which is now, itself, under the Airbus Military. The aircraft are manufactured from the Airbus Military facility located in Spain. A maritime patrol variant exists as the C295 MPA “Persuader” and features six hardpoints for the anti-submarine role. The model may be acquired by the British and is already in service with the Chilean Navy with another deal to an unnamed NATO member in the works. All fixed wing maritime patrol aircraft will have some form of ASW capability.

Rotary Wing ASW Platforms

Rotary wing platforms are a very popular choice for ASW as they can easily be carried on the ship and operate from its deck on as required basis. Some examples are:-

Lockheed Martin MH-60R Sea Hawk

Lockheed Martin MH-60R. The Indian Navy is in the process of acquiring 24 MH-60R helicopters to replace its Sea King ASW fleet. The MH-60R is a multirole maritime helicopter having a twin turboshaft engine based on the US Army UH-60 Black Hawk and a member of the Lockheed Martin (Sikorsky) S-70 family. It is the most capable naval helicopter available today designed to operate from frigates, destroyers, cruisers and aircraft carriers. The US Navy was the first to adopt the MH-60R maritime helicopter in 2006. Since then, the Navy’s fleet has grown to 300 MH-60Rs that complete missions like search for enemy submarines, conduct daring at-sea rescues and engage undersea threats.

US Navy is working with General Atomics Aeronautical Systems, Inc. (GA-ASI) to develop ASW capability for its new MQ-9B SeaGuardian Unmanned Aerial System (UAS).

The primary missions of the ‘Romeo’ helicopter are anti-submarine warfare and anti-surface warfare. Secondary missions include search and rescue, logistics support, personnel transport, and medical evacuation. The MH-60R avionics includes dual controls and instead of the complex array of dials and gauges used in other versions, it has four fully integrated 8” x 10” night vision goggle-compatible and sunlight-readable colour multi-function displays, all part of glass cockpit produced by Owego Helo Systems division of Lockheed Martin. The onboard sensors include AN/AAR-47 Missile Approach Warning System by Northrop Grumman (ATK), Raytheon AN/AAS-44 electro-optical system that integrates FLIR and laser rangefinder AN/ALE-39 decoy dispenser and AN/ALQ-144 infrared jammer by BAE Systems and many more sensors. It has a digital communications suite, common programmable keysets soon to be replaced with trackball, fully integrated Global Positioning System and Inertial Navigation System, Mass memory data storage and rugged integrated mission computer. For operations the helicopter is equipped with a sonobuoy launcher, forward-looking infrared radar, multi-mode radar, dipping sonar, integrated self-defence suite and four weapon stations to carry homing torpedoes and anti-ship missiles. The type of sensors and other avionics the IN has asked for is not known. The MH-60R Seahawk is the next generation of submarine hunters and anti-surface warfare helicopters. For naval combat missions, the MH-60R can be armed with AGM-114 Hellfire air-to-surface missiles to perform anti-surface warfare missions. It can be also be armed with Northrop Grumman (ATK) Mk50 or Mk46 active/passive lightweight torpedoes to conduct ASW. For its defence, the MH-60R is equipped with pintle-mounted 7.62mm machine gun. It has a maximum and cruise speed of 267 km/h and 168 km/h respectively, with a maximum flying range of 834 km.

NH90 NFH (Naval Frigate Helicopter). The NH90 NFH, offered by NH Industries, is an advanced ASW helicopter built by Thales. The helicopter is operated by the Italian Navy, French Navy, Royal Netherlands Navy, Norwegian Navy, and Belgian Navy. The NH90 NFH features a wide cabin to accommodate special operation troops or wounded personnel along with ASW/ASuW systems such as mission consoles, Sonobuoys, electronic support measures (ESM) and countermeasures. It has a takeoff weight of 11 tonne and can operate from a variety of vessels day and night and in all weather conditions. The helicopter is installed with FLASH (Folding Light Acoustic System for Helicopters) dipping sonar/sonics systems to detect quiet submarines operating in the open ocean and in littoral waters. The helicopter can be armed with two MU90/Mk46 or Stingray ASW torpedoes, has a range of 982 km, and can conduct ASW missions for up to four hours.

Z-18F. The Z-18F is an anti-submarine variant of the Z-18 medium-lift helicopter developed by the Changhe Aircraft Industry Group (CAIG). The helicopter, with a maximum take-off weight of 13.8 tonne, can be deployed on smaller surface combatants of the People’s Liberation Army Navy (PLAN). It forms a part of the helicopter wing aboard the Liaoning (CV-16) aircraft carrier. The Z-18F is equipped with an electro-optic/infrared sensor, a dipping sonar, and a chin-mounted surface search radar. It can carry up to 32 sonobuoys and four Yu-7 light-weight ASW torpedoes or YJ-9 anti-ship missiles. Z-18F ASW helicopter can attain a top speed of more than 330 km/h and a maximum range of 900 km.

Ka-27/Ka-28. The Kamov Ka-27 helicopter was developed for the Soviet Navy and was inducted in 1982. The first production variant was the Ka-27PL. Its export version is the Ka-28. Currently it is in service with various countries. The Ka-27 retains Kamov’s well-proven contra-rotating co-axial rotor configuration. This helicopter has no tail rotor, which allows to reduce footprint on ships. This ASW helicopter is extremely stable and easy to fly with automatic height hold, automatic transition to and from the hover, and auto hover are possible in all weather conditions. The Ka-27PL has all the usual ASW and ESM equipment including dipping sonar and sonobuoys as well as search radar. The Ka-27M is a recent version that is being tested and evaluated by the Russian Navy. The helicopter is capable of firing torpedoes and anti-submarine missiles and can also be armed with PLAB-250-120 anti-submarine bombs and OMAB bombs. The Ka-27 has a flight range of 900 km.

Unmanned Systems

General Atomics’ SeaGuardian. The Indian Navy has taken on lease two SeaGuardian drones to enhance surveillance over the Indian Ocean Region (IOR) but they can also be deployed in the Ladakh region if the need arises. The two non-weaponised MQ-9B SeaGuardian drones have been leased for one year with an option of extending the period by another year.

The US Navy is working with General Atomics Aeronautical Systems, Inc. (GAASI) to develop ASW capability for its new MQ-9B SeaGuardian Unmanned Aerial System (UAS). GA-ASI stated on January 20, 2021 that during recent tests, the Navy’s MQ-9 drone successfully tracked a small submersible target for three hours using 10 sonobuoys dropped from it. On November 24, 2020, GA-ASI successfully demonstrated an ‘A’ size sonobuoy carriage, release, process and control from a company-owned MQ-9A Block 5. GA-ASI first demonstrated a sonobuoy remote processing capability in 2017 from an MQ-9A. Since then, GA-ASI has added a Sonobuoy Management and Control System (SMCS) to monitor and control deployed sonobuoys and has developed a pneumatic sonobuoy dispenser system (SDS) capable of safely carrying and deploying 10 US Navy compliant ‘A’ size or 20 ‘G’ size sonobuoys per pod. In a standard Maritime ISR and ASW configuration, Sea-Guardian’s endurance exceeds 18 hours, having a mission radius of 1200 nautical miles with eight hours of on-station time for submarine detection and tracking, providing a low-cost complement to manned aircraft for manned-unmanned teaming (MUM-T) operations.