Saturday, February 24, 2024

Fighting against naval mines in shallow waters: the US Navy's Airborne Mine CounterMeasures

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The participation of the United States Navy in the forty-seventh edition of the BALTOPS ( BALTic OperationS ) was notably illustrated by the implementation for the first time in this exercise of the Airborne Mine CounterMeasures (AMCM) by Helicopter Sea Combat Squadron Two Eight (HSC 28). This is one of the rare operational solutions for combating naval mines in shallow waters (0 – 15 meters).

The fight against naval mines remains a fundamental issue in order to preserve the freedom of action of a State's fishing, commercial, military and scientific fleets, even pleasure fleets, in order to be able to exercise its right (Montego Bay Convention (1994 ) to freedom of navigation. Access to a port, a naval base, a channel, straits, places of concentration of navigation or entire areas can be undermined and therefore partially or totally restrict the freedom of maneuver of the protagonists concerned. -cities One of the major maritime characteristics is that maritime routes are the same for everyone.

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There are several types of naval mines – drifting, fixed in shallow or deep seas, intelligent mines – which detonate their charge according to one or more external stimuli. These may be contact mines (between it and the hull of the unfortunate vessel), magnetic influence, depression, by acoustic recognition, or even mines combining one or more of these stimuli. Some mines use a torpedo rather than an explosive charge.

The decontamination of these shallow waters is a revived issue because the diffusion of certain land-based techniques such as, for example, Improvised Explosive Devices ( IED) directly pollutes the shallow waters. The use of devices more or less artisanal mines, diversion of military equipment, or even the use of real naval mines has recently been demonstrated in Yemen (mining of the port of Hodeïda).

One of the greatest difficulties in the fight against mines is their location in shallow waters. It is possible to use active sonar to do this. But this must be placed at the front of the supporting building and oriented in the frontal sector. Most mine countermeasures sonars are aimed downward, so they can investigate the depths. Added to this material problem are the difficulties associated with operating the acoustic channel along the sea surface due to the propagation characteristics of sound waves. Knowing the presence of objects in shallow waters of 0 to -15 meters depth is one thing, locating them precisely is another.

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Other means were tried to get around this initial difficulty. Radar detection was experimented with, for example. Special treatments of the signal emitted by the radar were tried. Radio waves penetrate the liquid medium only a few meters. But these processes only give meager results, and only through a sea of ​​oil.

Optical observation gives some results for depths of 0 to -5 meters. This requires, however, being able to position yourself high enough to be able to see the underwater object, ideally from a helicopter. This technique is also based on fairly good environmental conditions.

From this perspective, laser detection ( LIght/Laser Detection And Ranging (LIDAR) is as much the most promising as the most effective of all these techniques. A LIDAR sensor integrated into an aerial platform (rotary or fixed wing aircraft) is capable of penetrate the sea from 0 to -10, or even -15 meters deep. Two uses are possible, even complementary: topo-bathymetric surveys (the Marine HydrOgraphic Service (SHOM) has been experimenting with the technique with the HawkEye III since 2015) and therefore the detection of underwater objects.

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The Airborne Mine CounterMeasures (AMCM) implemented by the Helicopter Sea Combat Squadron Two Eight (HSC 28) is one of the sets of the Mine Counter-Measure (MCM) module which equips the Littoral Combat Ships of the Independence and Freedom classes . The AMCM is based on two main pieces of equipment: the first is the Airborne Laser Mine Detection System (ALMDS). Hidden under this name is, precisely, a LIDAR integrated into a pod carried by a helicopter, MH-60S. The second is the Airborne Mine Countermeasures System – Archerfish (AMNS-AF).

Airborne Laser Mine Detection System Defense News | United States | Naval Mine Warfare
Airborne Laser Mine Detection System (ALMDS)

The ALMDS nacelle is therefore used to locate underwater objects with special treatments in order to be able to identify naval mines in shallow waters. Performance would be very good up to -15 meters. The fault of the system would affect its scanning capabilities.

The degree of reliability of the ALMDS system must also be considered in light of the fact that a competing capability embodied by the AQS-20A relies on the use of sonar. After receiving ten copies, this program was canceled.

Mines spotted must be destroyed. The use of a 30 mm cannon had been preferred until the development of this system. The problems of penetration into the marine element (reflection, resistance to advancement) of the shells – even supercavitating – do not offer all the guarantees necessary to detonate the naval mine. A magnetic dredge like the MK-105 Magnetic Influence Minesweeping System towed by a CH-53 Sea Dragon causes magnetic influence mines to react. But not the others.

Airborne Mine Countermeasures System Archerfis Defense News | United States | Naval Mine Warfare

The AMNS-AF offers an interesting technique for the re-acquisition of mines spotted by the ALMDS, their identification and their rapid neutralization. It is a pod that can deploy four torpedoes connected to it by an optical fiber, the head of which is equipped with a high-frequency sonar and a low-light optical channel. The Archerfish is therefore guided to the contact identified and classified as a probable mine by moving under its own power until it detonates if the contact is positive. The low volume of the system allows it to be integrated from surface drones to a helicopter.

Unlike the use of a remotely operated vehicle carrying out the same work, the AMNS-AF relies on a significantly higher speed of execution, which underlines the consistency of American choices in the fight against mines: being able to pass, despite naval mines, and quickly.

The technical proposal for the fight against naval mines in shallow waters contained in the Airborne Mine CounterMeasures (AMCM), one of the components of the Mine Counter-Measure (MCM) module of the Littoral Combat Ship, appears to be one of the most credible in the world. world, given the disappointments recorded by frontal sector sonars, if indeed they equip mine warships.

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Fabrice Wolf
Fabrice Wolf
A former French naval aeronautics pilot, Fabrice is the editor and main author of the site. His areas of expertise are military aeronautics, defense economics, air and submarine warfare, and Akita inu.

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