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133-642: Denmark dropped out and chose the EH101 , leaving Norway, Sweden, and Finland buying the NHI NH90 helicopter in September 2001. The helicopter was still in development and orders began in the late 2000s and early 2010s to the countries. In 2022 Norway terminated the order because NHI took to long to deliver working helicopters, leaving Sweden and Finland. Finland has 20 in service for Army transport, and Sweden has 18 with some for transport and some for SAR;Sweden uses

266-482: A probe for aerial refuelling . Self-sealing fuel tanks are an optional item to be selected by the customer. An inlet particle separator system can be installed, protecting the engine when operating in sandy environments. Most variants of the AW101 are equipped with self-defence systems, such as chaff and flare dispensers, directed infrared countermeasures (infrared jammers), ESM (electronic support measures in

399-417: A 35–40 lb (16–18 kg) cone-shaped steel drum on a 5 ft (1.5 m) shaft, intended to be thrown at a submarine. Firing Lyddite shells, or using trench mortars , was tried. Use of nets to ensnare U-boats was also examined, as was a destroyer, HMS  Starfish , fitted with a spar torpedo . To attack at set depths, aircraft bombs were attached to lanyards which would trigger their charges;

532-608: A Canadian competition to replace the shipboard Sea King fleet, but the Sikorsky CH-148 Cyclone was selected. In 2013, following difficulties with the CH-148 procurement, the Royal Canadian Air Force (RCAF) was reported to be seriously considering cancelling the contract with Sikorsky and was investigating the possibility of procuring the AW101 instead. However, an initial batch of six Cyclones

665-612: A Doppler velocity system (DVS) which provides relative ground velocities; the DVS is also linked into the AFCS as part of the autostabilisation system. For safety, the aircraft is equipped with obstacle and terrain avoidance warning systems, traffic collision avoidance system (TCAS), and both voice and flight data recorders . The AW101 was initially equipped with the Ferranti Blue Kestrel search and detection radar which

798-625: A combination of sensor and weapon technologies, along with effective deployment strategies and sufficiently trained personnel. Typically, sophisticated sonar equipment is used for first detecting, then classifying, locating, and tracking a target submarine. Sensors are therefore a key element of ASW. Common weapons for attacking submarines include torpedoes and naval mines , which can both be launched from an array of air, surface, and underwater platforms. ASW capabilities are often considered of significant strategic importance, particularly following provocative instances of unrestricted submarine warfare and

931-632: A common emergency egress system. The first HC4 began flight trials in September 2017, with an IOC in mid-2018; an interim folding main rotor head will be fitted to some HC3 for shipborne operations prior to the HC4 upgrade. Command of the UK Merlin HC3/3A fleet was formally transferred from the RAF to the Royal Navy during a ceremony at RAF Benson on 30 September 2014. As part of the same ceremony,

1064-462: A comparable WW2 submarine; in addition, they recharged their batteries using a snorkel and could complete a patrol without surfacing. This led to the introduction of longer-ranged forward-throwing weapons, such as Weapon Alpha , Limbo , RBU-6000 , and of improved homing torpedoes. Nuclear submarines , even faster still, and without the need to snorkel to recharge batteries, posed an even greater threat; in particular, shipborne helicopters (recalling

1197-429: A consortium in 1991 to perform the helicopter's complex systems integration. The AW101 features a network of helicopter management and mission systems designed to reduce pilot workload and enable the helicopter to undertake a wide variety of missions. A digital automatic flight control system (AFCS) is employed by the AW101. The AFCS allows the operation of a four-axis ( pitch , roll, yaw and collective ) autopilot and

1330-489: A contract was signed between AgustaWestland and the government, for the purchase of 16 AW101 helicopters. The agreement came about after fierce competition between different manufacturers to satisfy the Norwegian requirements. Participants were AgustaWestland , Eurocopter , NHIndustries , Sikorsky Aircraft Corporation and Boeing. The government considered that AgustaWestland AW101 met the requirements and specifications in

1463-554: A deployment in Afghanistan in 2014. In September 2013, Danish AW101s were to receive L-3 Wescam MX-15 electro-optical/infrared (EO/IR) sensors; SAR aircraft already carry the FLIR Systems Star Safire II EO/IR sensor. On 25 October 2007, a project started that had the intent to replace all Westland Sea King search and rescue helicopters with new rescue helicopters by 2020. On 19 December 2013,

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1596-403: A device intended for countermining , a "dropping mine". At Admiral John Jellicoe 's request, the standard Mark II mine was fitted with a hydrostatic pistol (developed in 1914 by Thomas Firth & Sons of Sheffield) preset for 45 ft (14 m) firing, to be launched from a stern platform. Weighing 1,150 lb (520 kg), and effective at 100 ft (30 m), the "cruiser mine"

1729-694: A full time basis. During the 2021 carrier strike group deployment to the Pacific, for instance, seven Merlins were embarked with the task group. In addition to its ASW role, the HM2 will be able to carry an airborne early warning (AEW) pod known as the Crowsnest, replacing the Sea King ASaC7 . In September 2011, Thales UK proposed re-using Sea King ASaC7 equipment, such as the Searchwater 2000, on

1862-410: A large role. The use of nuclear propulsion and streamlined hulls has resulted in submarines with high speed capability and increased maneuverability, as well as low "indiscretion rates" when a submarine is exposed on the surface. This has required changes both to the sensors and weapons used for ASW. Because nuclear submarines were noisy, there was an emphasis on passive sonar detection. The torpedo became

1995-407: A large, modern submarine fleet, because all had fallen in the grip of Mahanian doctrine which held guerre de course could not win a war. At the beginning of the conflict, most navies had few ideas how to combat submarines beyond locating them with sonar and then dropping depth charges on them. Sonar proved much less effective than expected, and was no use at all against submarines operating on

2128-703: A long tail boom (fixed-wing aircraft) or an aerodynamic housing carried on a deployable tow line (helicopters). Keeping the sensor away from the plane's engines and avionics helps eliminate interference from the carrying platform. At one time, reliance was placed on electronic warfare detection devices exploiting the submarine's need to perform radar sweeps and transmit responses to radio messages from home port. As frequency surveillance and direction finding became more sophisticated, these devices enjoyed some success. However, submariners soon learned not to rely on such transmitters in dangerous waters. Home bases can then use extremely low frequency radio signals, able to penetrate

2261-409: A medical team and 16 stretchers, and cargo pallets. The ramp, 1.91 by 2.3 metres (6 ft 3 in × 7 ft 7 in), can take a 3,050-kilogram (6,720 lb) load, allowing it to carry vehicles such as Land Rovers . The ramp and cabin floor are fitted with flush tie-down points. A cargo hook under the fuselage can carry external loads of 5,440 kilograms (11,990 lb) via the use of

2394-656: A meeting with their American counterparts in June 1917. In October 1918, there was a meeting in Paris on "supersonics", a term used for echo-ranging, but the technique was still in research by the end of the war. The first recorded sinking of a submarine by depth charge was U-68 , sunk by Q-ship HMS  Farnborough off County Kerry , Ireland 22 March 1916. By early 1917, the Royal Navy had also developed indicator loops which consisted of long lengths of cables lain on

2527-516: A ram with which to sink submarines, and U-15 was thus sunk in August 1914. During June 1915, the Royal Navy began operational trials of the Type D depth charge, with a 300 lb (140 kg) charge of TNT ( amatol , as TNT supplies became critical) and a hydrostatic pistol, firing at either 40 or 80 ft (12 or 24 m), and believed to be effective at a distance of 140 ft (43 m);

2660-471: A result, in the latter half of 1943, US subs were suddenly sinking Japanese ships at a dramatically higher rate, scoring their share of key warship kills and accounting for almost half of the Japanese merchant fleet. Japan's naval command was caught off guard; Japan had neither the anti-submarine technology or doctrine, nor the production capability to withstand a tonnage war of attrition , nor did she develop

2793-520: A semi-automatic cargo release unit (SACRU). A rescue hoist and a hover trim controller are fitted at the cargo door. An optional cargo winch can be installed near to the rear ramp. The British Royal Navy's final order was for 44 ASW aircraft, originally designated Merlin HAS.1 (Helicopter, Anti-Submarine Mark 1) but soon changed to Merlin HM1 (Helicopter, Maritime Mark 1). The first fully operational Merlin

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2926-598: A semi-autonomous oceangoing unmanned naval vessel. Today some nations have seabed listening devices capable of tracking submarines. It is possible to detect man-made marine noises across the southern Indian Ocean from South Africa to New Zealand. Some of the SOSUS arrays have been turned over to civilian use and are now used for marine research. Several countries developed anti-submarine missiles including United States , Russia , China , South Korea , Japan and India . Anti-submarine missiles give flexibility in terms of

3059-509: A separate competition, ultimately choosing the AW101 also. In 2022, after over two decades after its order, and waiting many years waiting for aircraft and other issues, Norway cancelled its 14 airframe NH90 order. Denmark dropped out of NHSP in September 2001 and instead chose the EH101, but Norway, Sweden, and Finland placed orders for the still in development, NH90, in various versions. AgustaWestland AW101 The AgustaWestland AW101

3192-571: A ship by an underwater vehicle are generally believed to have been during the American Revolutionary War , using what would now be called a naval mine but what was then referred to as a torpedo. Even so, various attempts to produce submarines had been made prior to this. In 1866, British engineer Robert Whitehead invented the first effective self-propelled torpedo, the eponymous Whitehead torpedo ; French and German inventions followed soon thereafter. The first submarine with

3325-507: A similar idea was a 16 lb (7.3 kg) guncotton charge in a lanyarded can; two of these lashed together became known as the Depth Charge Type A. Problems with the lanyards tangling and failing to function led to the development of a chemical pellet trigger as the Type B. These were effective at a distance of around 20 ft (6.1 m). Perhaps the best early concept arose in a 1913 RN Torpedo School report, describing

3458-459: A tail rotor failed due to a manufacturing defect. An improved tail rotor was designed and adopted on most AW101s which significantly reduced associated maintenance. In 1995, it was announced that the Navy's Westland Lynx helicopters would be retired in favour of an all-Merlin fleet. However, the subsequent Strategic Defence and Security Review 2010 stated that the future naval helicopters would be

3591-719: A torpedo was Nordenfelt I built in 1884–1885, though it had been proposed earlier. By the outbreak of the Russo-Japanese War , all the large navies except the Germans had acquired submarines. Nevertheless, by 1904, all powers still defined the submarine as an experimental vessel and did not put it into operational use. There were no means to detect submerged U-boats, and attacks on them were limited at first to efforts to damage their periscopes with hammers. The Royal Navy torpedo establishment, HMS Vernon , studied explosive grapnel sweeps; these sank four or five U-boats in

3724-750: Is a medium-lift helicopter in military and civil use. First flown in 1987, it was developed by a joint venture between Westland Helicopters in the United Kingdom and Agusta in Italy in response to national requirements for a modern naval utility helicopter. Several operators, including the armed forces of Britain, Denmark, and Portugal, use the name Merlin for their AW101 aircraft. It is manufactured at factories in Yeovil , England, and Vergiate , Italy. Licensed assembly work has also taken place in Japan and

3857-474: Is capable of 360 degree scanning and can detect small targets as far as 25 nautical miles away. As part of the Royal Navy's Merlin HM2 upgrade program, Lockheed Martin implemented a series of improvements to the radar, notably allowing it to track 40 times the number of targets previously capable. Danish EH101s are fitted with the RDR-1600 search and weather radar . Mk 2 Royal Navy Merlins are equipped with

3990-661: Is frequently utilised for troop transport duties and for the transport of bulky objects, either internally or underslung , including vehicles and artillery. The Merlin Depth Maintenance Facility at RNAS Culdrose performed most tasks upon the Merlin HC3. The Merlin's first operational deployment was to the Balkans region in 2003. RAF Merlins were first deployed to Iraq as part of Operation Telic in 2004, supporting coalition forces and were operated as

4123-640: The Fort Victoria class . 30 aircraft have been upgraded to Merlin HM2 standard under the £750m Merlin Capability Sustainment Programme; Lockheed Martin UK delivered the final HM2 on 11 July 2016. The HM2 has a new mission system, digital cockpit , electro-optical camera and multi-static sonar processing. The HM2 achieved IOC on 30 June 2014 after flying 480 hours from Illustrious during Exercise Deep Blue earlier that month. It

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4256-542: The R1 was the first ASW submarine. 211 of the 360 U-boats were sunk during the war, from a variety of ASW methods: This period saw the development of active sonar ( ASDIC ) and its integration into a complete weapons system by the British, as well as the introduction of radar . During the period, there was a great advance due to the introduction of electronics for amplifying, processing, and displaying signals. In particular,

4389-601: The 35th G8 summit . In 2010, the Italian Navy deployed three AW101s to Afghanistan, where they were flown in both the transport and utility roles. In 2011, it was reported that the Italian contingent in Afghanistan, consisting of AW101s, had been providing coverage of a wide area of the country. In June 2011 the AW101 was chosen by the Italian Air Force to replace its ageing Sea King HH-3F helicopters in

4522-493: The Admiralty . To attack submerged boats, a number of anti-submarine weapons were derived, including the sweep with a contact-fused explosive. Bombs were dropped by aircraft and depth charge attacks were made by ships. Prior to the introduction of dedicated depth charge throwers, charges were manually rolled off the stern of a ship. The Q-ship , a warship disguised as a merchantman, was used to attack surfaced U-boats, while

4655-693: The Canadian Armed Forces 's (CAF) Sea Kings, found itself subject to a wider political battle between the country's Conservative and Liberal parties, the latter viewing the aircraft as too costly. Critics attacked the EH101 purchase as excessive and unnecessary after the Cold War 's end in the early 1990s. Wide-ranging cost estimates were presented by both proponents and opponents of the EH101 procurement, with opponents backing life extensions of Sikorsky CH-124 Sea King and Boeing Vertol CH-113 Labrador helicopter fleets. The EH101 controversy

4788-506: The Danish Ministry of Defence reportedly could not afford the retrofitting of the AW101 fleet for Afghanistan operations, against earlier reports of a deployment in 2012. In February 2013, Aviation Week reported that earlier reliability problems had been resolved and that a full upgrade package would be applied to Danish AW101s; these included the addition of electronic warfare pods and a new electro-optical system, in advance of

4921-684: The General Electric CT7 producing 1,960 to 2,329 shp (1,462 to 1,737 kW) were the two available engine types, but by 2020 new aircraft were only being sold with the CT7-8E. The RTM322 powerplant was specifically developed for the AW101; it was subsequently adopted on the AgustaWestland WAH-64 Apache and the NHIndustries NH90 helicopters. According to Rolls-Royce, about 80% of AW101s use

5054-559: The Italian Navy , with options for four more. These AW101 included eight of the anti-surface/submarine (ASuW/ASW) version, four airborne early warning (AEW), four amphibious support helicopters (ASH). The government then exercised its option for four additional ASH helicopters, which were delivered by 2006. The same year the government ordered two more AW101 ASH helicopters in a slightly modified version. The first Italian Navy production helicopter ( MM81480 ) flew on 4 October 1999 and

5187-483: The Marte anti-ship missile on the AW101; as of 2011, the Royal Navy is considering equipping their Merlin fleet with an anti-surface missile. The Mk1, Mk3 and Mk3A variants can mount general purpose machine guns in up to five locations in the main cabin, aimed out of both door and window apertures. AgustaWestland has examined the integration of rockets and additional ground-attack weapons . Westland and IBM formed

5320-678: The Royal Danish Air Force (RDAF) announced the purchase of eight EH101s for SAR duties and six tactical troop transports for 722 Squadron. The last of the 14 AW101s was delivered in March 2007 and the first SAR AW101s became operational out of Karup Airport in April 2007. In 2007, the six troop transport AW101s were transferred to the British MOD; in exchange, the British government ordered six new-build AW101s as replacements for

5453-660: The Second World War , the Allies developed a huge range of new technologies, weapons and tactics to counter the submarine danger. These included: Italian and German submarines operated in the Mediterranean on the Axis side while French and British submarines operated on the side of the Allies. The German Navy sent 62 U-boats to the Mediterranean; all were lost in combat or scuttled. German subs first had to pass through

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5586-692: The Sikorsky SH-3 Sea King , performing roles such as medium-sized transport, anti-submarine warfare , search and rescue , and ship-based utility operations. The Royal Canadian Air Force (RCAF) operates the CH-149 Cormorant variant for air-sea rescue . Another variant, the Lockheed Martin VH-71 Kestrel , was produced to serve in the United States presidential transport fleet before the program

5719-556: The United States . Prior to 2007, the aircraft had been marketed under the designation EH101 . The original designation was EHI 01, from the name given to the Anglo-Italian joint venture—European Helicopter Industries—but a transcription error changed this to EH101. In 2000, Westland Helicopters and Agusta merged to form AgustaWestland , leading to the type's current designation. The AW101 entered into service in 1999 and has since replaced several older helicopter types, such as

5852-589: The Whiskey and Zulu classes. Britain also tested hydrogen peroxide fuels in Meteorite , Excalibur , and Explorer , with less success. To deal with these more capable submarines new ASW weapons were essential. This new generation of diesel electric submarine, like the Type XXI before it, had no deck gun and a streamlined hull tower for greater underwater speed, as well as more storage battery capacity than

5985-511: The Wolfpack achieved initial success, but became increasingly costly as more capable ASW aircraft were introduced. Technologies such as the Naxos radar detector gained only a temporary reprieve until detection apparatus advanced yet again. Intelligence efforts, such as Ultra , had also played a major role in curtailing the submarine threat and guiding ASW efforts towards greater success. During

6118-530: The blimps of World War I) have emerged as essential anti-submarine platforms. A number of torpedo carrying missiles such as ASROC and Ikara were developed, combining ahead-throwing capability (or longer-range delivery) with torpedo homing. Since the introduction of submarines capable of carrying ballistic missiles , great efforts have been made to counter the threat they pose; here, maritime patrol aircraft (as in World War II) and helicopters have had

6251-581: The combat search and rescue role. A total of 15 helicopters in the HH-101A variant were ordered and delivered between 2016 and 2020. In 1997, in light of the declining condition of its helicopter fleet, Canada launched the Canadian Search and Rescue Helicopter competition. It was won by the EH101, which was designated CH-149 Cormorant in Canadian service. In 2004, the EH101 was entered into

6384-491: The postwar era, ASW continued to advance, as the arrival of nuclear submarines had rendered some traditional techniques less effective. The superpowers of the era constructed sizable submarine fleets, many of which were armed with nuclear weapons ; in response to the heightened threat posed by such vessels, various nations chose to expand their ASW capabilities. Helicopters , capable of operating from almost any warship and equipped with ASW apparatus, became commonplace during

6517-463: The "high readiness" aircraft carrier. Problems with Merlin/Crowsnest have caused the Royal Navy to look for a replacement. As of 2023 the system, which is still to achieve full operating capability, has a planned retirement date of 2029. In 2021, the UK’s Defence and Security Accelerator (DASA) announced that options would be examined and might draw on the already existing Project Vixen , researching

6650-484: The "life and death" urgency in the Atlantic. However, US Vice Admiral Charles A. Lockwood pressured the ordnance department to replace the faulty torpedoes; famously when they initially ignored his complaints, he ran his own tests to prove the torpedoes' unreliability. He also cleaned out the "deadwood", replacing many cautious or unproductive submarine skippers with younger (somewhat) and more aggressive commanders. As

6783-470: The "range recorder" was a major step that provided a memory of target position. Because the propellers of many submarines were extremely loud in the water (though it doesn't seem so from the surface), range recorders were able to gauge the distance from the U-boat by sound. This would allow mines or bombs around that area to be detonated. New materials for sound projectors were developed. Both the Royal Navy and

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6916-526: The 1960s. Increasingly capable fixed-wing maritime patrol aircraft were also widely used, capable of covering vast areas of ocean. The Magnetic Anomaly Detector (MAD), diesel exhaust sniffers , sonobuoys and other electronic warfare technologies also became a staple of ASW efforts. Dedicated attack submarines , purpose-built to track down and destroy other submarines, became a key component as well. Torpedo carrying missiles, such as ASROC and Ikara , were another area of advancement. The first attacks on

7049-551: The 9-15 ton range and possibly license built. The NHindustries NH90 was chosen in September 2001 as the Nordic Standard Helicopter winner, with orders for 18 from Sweden, 14 for Norway, and 20 for Finland. At the same time, Denmark dropped out of NHSP and chose the EH101, but Norway, Sweden, and Finland placed orders for the still in development, NH90, in various versions. In September 2001 Norwegian Armed Forces chose to purchase fourteen NH90 units. The plan

7182-530: The AQS903 anti-submarine system for processing sonographic data from sonobuoys to detect and target submerged submarines. The AQS903 was derived from the AQS901 system on the earlier Hawker Siddeley Nimrod maritime patrol aircraft. The AW101 is typically operated by a crew of three: a pilot, an observer, and a crewman/operator. The pilot is able to fly for the majority of a mission in a hands-off mode, enabled by

7315-484: The AW101 can be flown by a single person. The pilots' instrument displays include six full-colour high-definition screens and an optional mission display; a digital map or forward looking infrared (FLIR) display can also be installed. The AW101 is powered by three turboshaft engines. Initially the Rolls-Royce Turbomeca RTM322 producing 2,035 to 2,160 shp (1,517 to 1,611 kW) and

7448-453: The AW101 to maintain a stable hover in 74 km/h (40 kn) crosswinds . An active vibration control system, known as the active control of structural response system , reduces airframe vibration by up to 80%, increasing crew comfort and minimising buildup of stress on the airframe. The cockpit is fitted with armoured seats for the crew, and can withstand an impact velocity of over 10 m/s. Dual flight controls are provided, though

7581-659: The Allied merchant convoys and strategic shipping lanes to any degree that German U-boats did. One major advantage the Allies had was the breaking of the Japanese "Purple" code by the US, so allowing friendly ships to be diverted from Japanese submarines and allowing Allied submarines to intercept Japanese forces. In 1942 and early 1943, US submarines posed little threat to Japanese ships, whether warships or merchant ships. They were initially hampered by poor torpedoes, which often failed to detonate on impact, ran too deep, or even ran wild. As

7714-516: The Crowsnest. Initial operating capability of the system was significantly delayed. While Crowsnest was deployed with the U.K. carrier strike group in 2021, it experienced operating challenges and revised plans meant that Crowsnest achieved initial operating capability in July 2023. Full operating capability is expected in 2024/25. It has been reported that initially only five Merlins will be equipped with Crowsnest, three of these being normally assigned to

7847-726: The FFS to provide rear crew training. The first training course at the centre started prior to delivery of the first rotorcraft. The training centre will be used by both Norwegian and foreign AW101 customers. Anti-submarine warfare Anti-submarine warfare ( ASW , or in the older form A/S ) is a branch of underwater warfare that uses surface warships , aircraft , submarines , or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typically carried out to protect friendly shipping and coastal facilities from submarine attacks and to overcome blockades . Successful ASW operations typically involved

7980-470: The First World War. A similar approach featured a string of 70 lb (32 kg) charges on a floating cable, fired electrically; an unimpressed Admiral Edward Evans considered any U-boat sunk by it deserved to be. Another primitive technique of attacking submarines was the dropping of 18.5 lb (8.4 kg) hand-thrown guncotton bombs. The Lance Bomb was developed, also; this featured

8113-804: The HCV high cabin variant. Norway took initiative in 1998 to establish the Nordic Standard Helicopter Program (NSHP), which would see a common unified model for the three Nordic countries. Four helicopters were considered: the AgustaWestland AW101 , the NHIndustries NH90 , the Eurocopter AS532 Cougar and the Sikorsky S-92 . In 1999, Norway, Denmark, Sweden, and Finland issued the specs for potential joint helicopter purchase, that would be in

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8246-425: The Italian company Agusta ; Westland and Agusta soon began talks regarding the joint development of a successor helicopter. Agusta and Westland finalised an agreement to work on the project together, and formed a jointly owned new company, EH Industries Limited (EHI), to pursue the development and marketing of the new helicopter to potential operators. On 12 June 1981, the UK government confirmed its participation in

8379-550: The Merlin and the Wildcat, a derivative of the Lynx. Royal Navy Merlins have seen action in the Caribbean, on counter-narcotics and hurricane support duties, as well as maritime security duties in the Persian Gulf . Merlins have also seen active duty in Iraq, providing support to British and coalition forces based in the region. The Merlin HM1 has been cleared to operate from the Royal Navy's aircraft carriers , amphibious assault ships , Type 23 frigates , Type 45 destroyer and several Royal Fleet Auxiliary (RFA) vessels including

8512-413: The Merlin; Lockheed Martin has proposed developing a new multi-functional sensor for both the AW101 and other aircraft. Lockheed originally planned to use a derivative of the F-35's APG-81 radar; however, a rival Elta system and the Thales system both commenced flight trials in 2014. On 22 May 2015, the MOD and prime contractor Lockheed Martin UK selected Thales to provide the radar and mission system for

8645-454: The Navy developed and introduced the Kyushu Q1W anti-submarine bomber into service in 1945. The Japanese depth charge attacks by its surface forces initially proved fairly unsuccessful against U.S. fleet submarines. Unless caught in shallow water, a U.S. submarine commander could normally escape destruction, sometimes using temperature gradients ( thermoclines ). Additionally, IJN doctrine emphasized fleet action, not convoy protection, so

8778-437: The Pacific, mainly against coastal shipping. In the immediate postwar period, the innovations of the late war U-boats were quickly adopted by the major navies. Both the United Kingdom and The United States studied the German Type XXI and used the information to modify WW2 fleet boats, the US with the GUPPY program and the UK with the Overseas Patrol Submarines Project. The Soviets launched new submarines patterned on Type XXIs,

8911-433: The RAF's 78 Sqn was disbanded and the Royal Navy's 846 Naval Air Squadron stood-up with the Merlin. The RAF's 28(AC) continued to operate as part of the Commando Helicopter Force until July 2015, when 28(AC) Sqn stood down and 845 Naval Air Squadron stood-up. 846 NAS relocated from RAF Benson to RNAS Yeovilton in March 2015, with 845 NAS following in June 2016. In 1997, the Italian government ordered 16 AW101 helicopters for

9044-438: The RDAF. Danish AW101s have a higher gross weight capacity of 15,600 kg and were, as delivered, coated in a paint designed to reduce the aircraft's infrared signature . In the SAR role, RDAF AW101s have a crew of six and were initially painted yellow to distinguish themselves from AW101 allocated to military duties, but were later painted green, and all 14 AW101s are used for SAR and troop transport. On 28 January 2008,

9177-419: The RTM322 The engines power an 18.59 m (61 ft 0 in) diameter five-bladed main rotor. The rotor blades are constructed from carbon/glass with nomex honeycomb and rohacell foam, edged with titanium alloy in a sandwich construction . The shaping of the main rotor blades is derived from the BERP rotor blades first used on the Westland Lynx . This blade design improves aerodynamic efficiency at

9310-425: The Royal Navy for use by the Commando Helicopter Force. Royal Navy personnel worked alongside RAF crew at Benson to build experience during the transition. The £454m Merlin Life Sustainment Programme resulted in 25 HC3/3A airframes being fitted with the cockpit electronics of the HM2, folding tails and main rotor heads, strengthened landing gear, deck lashing mounting points, obsolescence updates, fast-roping points and

9443-421: The Type D*, with a 120 lb (54 kg) charge, was offered for smaller ships. In July 1915, the British Admiralty set up the Board of Invention and Research (BIR) to evaluate suggestions from the public as well as carrying out their own investigations. Some 14,000 suggestions were received about combating submarines. In December 1916, the RN set up its own Anti-Submarine Division (ASD), from which came

9576-409: The U.S. Navy fitted their destroyers with active sonars. In 1928, a small escort ship was designed and plans made to arm trawlers and to mass-produce ASDIC sets. Several other technologies were developed; depth sounders that allowed measurement by moving ships were a new innovation, along with a greater appreciation of the properties of the ocean that affected sound propagation. The bathythermograph

9709-433: The US submarine menace was slight in the beginning, Japanese commanders became complacent and as a result did not invest heavily into ASW measures or upgrade their convoy protection to any degree to what the Allies in the Atlantic did. Often encouraged by the Japanese not placing a high priority on the Allied submarine threat, US skippers were relatively complacent and docile compared to their German counterparts, who understood

9842-612: The a SAR helicopter which lead to Norway's NAWSARH procurement program with Iceland in the 2010s. In September 2001, Denmark did not choose the NH90 which reduced the NHSP countries from four to three, and the Danish ended up choosing EH101 to replace their aging Sikorsky S-61 fleet. Norway ended up running the NAWSARH with Iceland (though Iceland pulled out in 2012) to select a SAR helicopter in

9975-485: The automatic stabilisation system, and is linked in with the aircraft's flight management systems. The AFCS, manufactured by Smiths Aerospace , is a dual-duplex system using two flight computers to provide redundancy and fault-tolerance . The AW101's navigation system includes a GPS receiver and inertial navigation system , VHF omnidirectional radio range (VOR), instrument landing system (ILS), TACAN , and automatic direction finding. The Mk1 and Mk3 are equipped with

10108-417: The best possible way. On 12 June 2017, Per-Willy Amundsen , Minister of Justice and Public Security , announced the opening of Leonardo's AW101 Norway Training Centre at Stavanger Sola Air Station . The training centre includes an AW101 Full Flight Simulator (FFS), jointly developed by Leonardo and CAE to Level D, which is a CAE Series 3000 device, along with an AW101 SAR console training system linked to

10241-487: The best ships and crews went elsewhere. Moreover, during the first part of the war, the Japanese tended to set their depth charges too shallow, unaware U.S. submarines could dive below 150 feet (45m). Unfortunately, this deficiency was revealed in a June 1943 press conference held by U.S. Congressman Andrew J. May , and soon enemy depth charges were set to explode as deep as 250 feet (76m). Vice Admiral Charles A. Lockwood , COMSUBPAC , later estimated May's revelation cost

10374-493: The blade tip and reduces the acoustic signature . Improved BERP IV rotors have since been developed; when installed this increases the AW101's maximum take-off weight. Each engine is supplied by a separate 1,074 L (284 US gal; 236 imp gal) fuel tank using dual booster pumps. Optional fourth and fifth tanks can be added to act as a reservoir supply, topping up the main tanks during flight, increasing range or endurance. The AW101 can also be fitted with

10507-433: The combined operational fleet had also accumulated a total of 170,000 flying hours. In November 2007, Algeria signed a contract for six AW101 helicopters. In August 2012, it was reported that Algeria had signed an agreement with AgustaWestland for the provision of up to 80 helicopters, 42 of which were to be AW101s. Under the terms of this arrangement, early aircraft were to be manufactured by AgustaWestland, while Algeria

10640-527: The crash of the second pre-production aircraft on 21 January 1993. On 6 June 1993, the first EH101 took its maiden flight with the Rolls-Royce Turbomeca RTM322 turboshaft engine. Nine prototypes were built to explore military and civil applications, including a "heliliner" configuration. In February 1995, Britain formally placed its first order for a total of 22 EH101s; this was quickly followed by Italy's order for 16 EH101s in October 1995. The EH101 order

10773-440: The design of the rotor blades, avionics systems, and extensive use of composite materials. The fuselage structure is modular and comprises an aluminium–lithium alloy , designed to be both light and damage-resistant. The AW101 is designed for operating in extreme weather conditions; it is fitted with a de-icing system and rated to operate in temperatures ranging between −45 and +50 °C. The aircraft's control systems allow

10906-478: The drive shaft of a Danish AW101 broke, leading to an emergency landing at Billund Airport. Following the incident, the Danish fleet was grounded as a precaution and the AW101's future was publicly debated. In the first six months of 2008, the RDAF reported an operational availability of roughly 50%, well below the target of 80%, partly due to an inadequate maintenance organisation and staff shortages. In January 2011,

11039-530: The early part of the Pacific War, Japanese subs scored several tactical victories, three successful torpedo strikes on the US fleet carriers Yorktown (CV-5), USS  Saratoga and USS  Wasp (CV-7), The Saratoga survived the attack and was repaired, while the Yorktown and Wasp were both abandoned and scuttled as a result of the attack. The USS North Carolina (BB-55) received a single torpedo in

11172-399: The end of World War II . While dipping hydrophones appeared before war's end, the trials were abandoned. Seaplanes and airships were also used to patrol for submarines. A number of successful attacks were made, but the main value of air patrols was in driving the U-boat to submerge, rendering it virtually blind and immobile. However, the most effective anti-submarine measure was

11305-440: The endurance of small submarines. Previously the emphasis had been largely on deep water operation but this has now switched to littoral operation where ASW is generally more difficult. There are a large number of technologies used in modern anti-submarine warfare: In modern times forward looking infrared (FLIR) detectors have been used to track the large plumes of heat that fast nuclear-powered submarines leave while rising to

11438-575: The face of advances in Soviet submarine technology. Westland Helicopters put together a proposal, designated WG.34 , for a three-engined helicopter of similar dimensions to the Sea King; the WG.34 was to feature more autonomy and a greater range than its predecessor. At the same time, the Italian Navy ( Marina Militare ) was also considering the replacement of its fleet of Sea Kings, which had been built by

11571-522: The fact a submarine of the day was often on the surface for a range of reasons, such as charging batteries or crossing long distances. The first approach to protect warships was chainlink nets strung from the sides of battleships , as defense against torpedoes . Nets were also deployed across the mouth of a harbour or naval base to stop submarines entering or to stop torpedoes of the Whitehead type fired against ships. British warships were fitted with

11704-456: The five final assembly locations for the NH90 including France, Germany, Italy, and Australia. The helicopters for Finland, Norway, and Sweden were mostly assembled at Patria, Finland. The choice was met with resistance from the SAR community which felt the NH90 was too small, and this one reason Denmark had pulled out and chose the EH101. Years of lawsuits led to demands for more open competition for

11837-445: The form of RF heads), and a laser detection and warning system. British Merlins have been outfitted with protective armour against small-arms fire. A side-mounted forward looking infrared (FLIR) imaging sensor has been fitted to some variants. Two hardpoints are present in the underside of the airframe on which the HM1 model can carry four Sting Ray torpedoes or Mk 11 Mod 3 depth charges . Some customers have chosen to deploy

11970-504: The helicopter has been used solely for sensing and rocket delivered torpedoes used as the weapon. Surface ships continue to be an important ASW platform because of their endurance, now having towed array sonars. Submarines are the main ASW platform because of their ability to change depth and their quietness, which aids detection. In early 2010 DARPA began funding the ACTUV programme to develop

12103-405: The highly defended Straits of Gibraltar , where nine were sunk, and a similar number damaged so severely they had to limp back to base. The Mediterranean is calmer than the Atlantic, which made escape for U-boats more difficult and was ringed with Allied air bases. Similar ASW methods were used as in the Atlantic but an additional menace was the use by Italians of midget submarines. Operating under

12236-653: The introduction of submarine-launched ballistic missiles , which greatly increased the lethality of submarines. At the beginning of the twentieth century, ASW techniques and submarines themselves were primitive. During the First World War , submarines deployed by Imperial Germany proved themselves to be a capable threat to shipping, being capable of striking targets even out in the North Atlantic Ocean. Accordingly, multiple nations embarked on research into devising more capable ASW methods, resulting in

12369-570: The introduction of escorted convoys , which reduced the loss of ships entering the German war zone around the British Isles from 25% to less than 1%. The historian Paul E. Fontenoy summarised the situation as: "[t]he convoy system defeated the German submarine campaign ." A major contributing factor was the interception of German submarine radio signals and breaking of their code by Room 40 of

12502-457: The introduction of practical depth charges and advances in sonar technology; the adoption of the convoy system also proved to be a decisive tactic. After a lull in progress during the interwar period, the Second World War would see submarine warfare and ASW alike advance rapidly, particularly during the critical Battle of the Atlantic , during which Axis submarines sought to prevent Britain from effectively importing supplies. Techniques such as

12635-511: The largest and longest range vessels of their type and were armed with the Type 95 torpedo . However, they ended up having little impact, especially in the latter half of the war. Instead of commerce raiding like their U-boat counterparts, they followed the Mahanian doctrine, serving in offensive roles against warships, which were fast, maneuverable and well-defended compared to merchant ships. In

12768-573: The main medevac asset in southern Iraq; both Flight Lieutenant Kev Harris and Flight Lieutenant Michelle Goodman were awarded the DFC during this period. Merlins routinely operated around Basra until Britain's withdrawal in June 2009. In 2002, Westland made an unsuccessful unsolicited offer to the British Ministry of Defence , proposing an enhanced Merlin variant intended to satisfy the demand for additional lift capacity. An alternative measure

12901-409: The main weapon (though nuclear depth charges were developed). The mine continued to be an important ASW weapon. In some areas of the ocean, where land forms natural barriers, long strings of sonobuoys, deployed from surface ships or dropped from aircraft, can monitor maritime passages for extended periods. Bottom mounted hydrophones can also be used, with land based processing. A system like this SOSUS

13034-478: The navy as many as ten submarines and 800 crewmen. Much later in the war, active and passive sonobuoys were developed for aircraft use, together with MAD devices. Toward the end of the war, the Allies developed better forward-throwing weapons, such as Mousetrap and Squid , in the face of new, much better German submarines, such as the Type XVII and Type XXI . British and Dutch submarines also operated in

13167-562: The needs of various civilian or military customers. The first prototype flew on 9 October 1987. In 1987, Canada selected the EH101 to replace its Sea Kings in the anti-submarine warfare and search and rescue roles. The EH101's third engine and increased range compared favourably with rival aircraft, such as the Sikorsky Seahawk . The range and de-icing capability were also seen as vital for North Atlantic operations. The fledgling EH101, of which up to 50 were on order to replace

13300-476: The ocean's surface, to reach submarines wherever they might be. The military submarine is still a threat, so ASW remains a key to obtaining sea control. Neutralizing the SSBN has been a key driver and this still remains. However, non-nuclear-powered submarines have become increasingly important. Though the diesel-electric submarine continues to dominate in numbers, several alternative technologies now exist to enhance

13433-464: The organizations needed (unlike the Allies in the Atlantic). Japanese antisubmarine forces consisted mainly of their destroyers, with sonar and depth charges. However, Japanese destroyer design, tactics, training, and doctrine emphasized surface nightfighting and torpedo delivery (necessary for fleet operations) over anti-submarine duties. By the time Japan finally developed a destroyer escort , which

13566-420: The project, allocated an initial budget of £20 million to develop nine pre-series examples. A major agreement, which secured funding for the majority of the EH101's development program, was signed by both the British and Italian governments in 1984. At the 1985 Paris Air Show , Agusta showed a mock-up of a utility version of the new helicopter, leading to a more generalised design that could be customised to meet

13699-695: The same attack with the USS Wasp, causing it to miss critical naval actions of the Guadalcanal campaign. Once the US was able to ramp up construction of destroyers and destroyer escorts , as well as bringing over highly effective anti-submarine techniques learned from the British from experiences in the Battle of the Atlantic , they would take a significant toll on Japanese submarines, which tended to be slower and could not dive as deep as their German counterparts. Japanese submarines, in particular, never menaced

13832-428: The same clear-water conditions in the Mediterranean – such that British submarines were painted dark blue on their upper surfaces to make them less visible from the air when submerged at periscope depth – the Royal Navy, mostly operating from Malta , lost 41 submarines to the opposing German and Italian forces, including HMS Upholder and HMS Perseus . Japanese submarines pioneered many innovations, being some of

13965-514: The seabed to detect the magnetic field of submarines as they passed overhead. At this stage, they were used in conjunction with controlled mines which could be detonated from a shore station once a 'swing' had been detected on the indicator loop galvanometer . Indicator loops used with controlled mining were known as 'guard loops'. By July 1917, depth charges had developed to the extent that settings of between 50–200 ft (15–61 m) were possible. This design would remain mainly unchanged through

14098-589: The ships actually monitoring the enemy submarine. Submerged submarines are generally blind to the actions of a patrolling aircraft until it uses active sonar or fires a weapon, and the aircraft's speed allows it to maintain a fast search pattern around the suspected contact. Increasingly anti-submarine submarines, called attack submarines or hunter-killers, became capable of destroying, particularly, ballistic missile submarines. Initially these were very quiet diesel-electric propelled vessels but they are more likely to be nuclear-powered these days. The development of these

14231-481: The sophisticated autopilot. All crew members have individual access to management computers and tactical information. The fuselage has a volume of 31.91 cubic metres (1,127 cu ft) and the cargo compartment is 6.5 metres (21 ft) in length, 2.3 metres (7 ft 7 in) wide and 1.91 metres (6 ft 3 in) high. The military version of the AW101 can accommodate up to 24 seated or 45 standing combat troops and their equipment. Alternative loads include

14364-408: The successive generations of Allied airborne radar. The first generation of Allied airborne radar used a 1.7 meter wavelength and had a limited range. By the second half of 1942 the " Metox " radar detector was used by U-boats to give some warning from airborne attack. During 1943, the Allies began to deploy aircraft equipped with new cavity magnetron-based 10-centimeter wavelength radar (ASV III), which

14497-499: The surface, as U-boats routinely did at night. The Royal Navy had continued to develop indicator loops between the wars but this was a passive form of harbour defense that depended on detecting the magnetic field of submarines by the use of long lengths of cable lain on the floor of the harbour. Indicator loop technology was quickly developed further and deployed by the US Navy in 1942. By then, there were dozens of loop stations around

14630-624: The surface. FLIR devices are also used to see periscopes or snorkels at night whenever a submariner might be incautious enough to probe the surface. Satellites have been used to image the sea surface using optical and radar techniques. Fixed-wing aircraft, such as the P-3 Orion & Tu-142 provide both a sensor and weapons platform similar to some helicopters like the Sikorsky SH-60 Seahawk , with sonobuoys and/or dipping sonars as well as aerial torpedoes . In other cases

14763-497: The term "Asdic", but relations with the BIR were poor. After 1917, most ASW work was carried out by the ASD. In the U.S., a Naval Consulting Board was set up in 1915 to evaluate ideas. After American entry into the war in 1917, they encouraged work on submarine detection. The U.S. National Research Council , a civilian organization, brought in British and French experts on underwater sound to

14896-527: The utility of a naval unmanned system that could encompass strike, AEW, and air-to-air refuelling components. If implemented, the replacement of Merlin/Crowsnest by another system would permit all Merlin helicopters to focus on ASW operations for the remainder of their service lives. On 15 December 2009, plans were announced to transfer RAF Merlin HC3s and HC3As to the Royal Navy's Commando Helicopter Force to replace retiring Sea King HC4 helicopters. The Sea King

15029-513: The world. Sonar was far more effective and loop technology for ASW purposes was discontinued shortly after the conflict's end. The use and improvement of radar technology was one of the most important elements in the fight against submarines. Locating submarines was the first step in being able to defend against and destroy them. Throughout the war, Allied radar technology was much better than their German counterparts. German U-boats struggled to have proper radar detection capabilities and keep up with

15162-529: Was also a potential hazard to the dropping ship. During the First World War , submarines were a major threat. They operated in the Baltic, North Sea, Black Sea and Mediterranean as well as the North Atlantic. Previously, they had been limited to relatively calm and protected waters. The vessels used to combat them were a range of small, fast surface ships using guns and good luck. They mainly relied on

15295-529: Was also reported that some of the eight airframes not scheduled to be upgraded for financial reasons may be updated. Five HM2s are in maintenance at a time, leaving 25 available, of which 14 were theoretically to be assigned to the Queen Elizabeth -class aircraft carrier . However, in practice with just 30 Merlin HM2s in service, it may be impossible to deploy 14 aircraft on a single operational carrier on

15428-553: Was announced that Boeing had acquired a manufacturing licence and the rights from AgustaWestland for US production of a localised AW101 variant, designated as the Boeing 101. In October 2012, the aircraft was submitted in a U.S. Air Force competition to replace the HH-60 Pave Hawk ; however, the bid was dropped three months later. The AW101 follows a conventional design layout, but makes use of advanced technologies, such as

15561-583: Was cancelled and the aircraft sold off to Canada for parts. Civil operators use the AW101 for passenger and VIP transportation. The type has been deployed to active combat theatres, such as in support of coalition forces during the Iraq War and the war in Afghanistan . In 1977, the UK Ministry of Defence issued a requirement for an anti-submarine warfare (ASW) helicopter to replace the Royal Navy 's Westland Sea Kings , which were becoming inadequate in

15694-609: Was confirmed that their Out of Service Date (OSD) had been moved to 2040. By the end of 2022, all HC helicopters were upgraded to the HC4/4A Commando Merlin standard. The RAF ordered 22 Merlin HC3 for transport missions, the first of which entered service in January 2001 with No. 28 Squadron RAF based at RAF Benson . The type is equipped with extended-range fuel tanks and is capable of air-to-air refuelling. The Merlin

15827-544: Was criticised as the aircraft reportedly lacked protective Kevlar armour. By July 2010, the Merlin fleet was fully fitted with ballistic armour. The deployment of Merlins to Afghanistan allowed the detachment of Sea Kings to be withdrawn from the region in October 2011. As part of the UK drawdown in Afghanistan, Merlins were withdrawn from theatre in June 2013. In 2012, the RAF's Merlin HC3/3A fleet began to be transferred to

15960-612: Was delivered on 17 May 1997, entering service on 2 June 2000. All aircraft were delivered by the end of 2002, and are operated by 3 Fleet Air Arm squadrons: 814 NAS , 820 NAS , 824 NAS and 829 NAS (now disbanded and merged with 814 NAS), all based at RNAS Culdrose in Cornwall. 700 NAS was the Merlin Operational Evaluation Unit from 2000 to 2008. In March 2004, Navy Merlins were temporarily grounded following an incident at RNAS Culdrose in which

16093-471: Was delivered to the RCAF in June 2015. In December 2022, Canada's Department of National Defence announced a C$ 1.24-billion contract for procurement of three additional aircraft and upgrades to the existing fleet to current configuration of the helicopter; this will increase the fleet to 16 aircraft. The RCAF also acquired its own advanced training simulator configured to the new modernized cockpit. In 2001,

16226-530: Was deployed by the US in the GIUK gap and other strategically important places. Airborne ASW forces developed better bombs and depth charges , while for ships and submarines a range of towed sonar devices were developed to overcome the problem of ship-mounting. Helicopters can fly courses offset from the ships and transmit sonar information to their combat information centres . They can also drop sonobuoys and launch homing torpedoes to positions many miles away from

16359-543: Was for eight of the Norwegian helicopters would go to the Coast Guard and the rest will serve on the frigates. Sweden and Finland also placed orders, and airframes for all three would be assembled mostly in Patria, Finland. (As mentioned elsewhere, the Norwegian functional airframes took so long to deliver, they cancelled the order over two decades later) The NH90 for the NHSP order were assembled in Patria, Finland; one of

16492-674: Was invented in 1937, which became a common fixture amongst ASW ships within only a few years. There were relatively few major advances in weapons during the period; however, the performance of torpedoes continued to improve. During the Second World War , the submarine menace revived, threatening the survival of island nations like Britain and Japan which were particularly vulnerable because of their dependence on imports of food, oil, and other vital war materials. Despite this vulnerability, little had been done to prepare sufficient anti-submarine forces or develop suitable new weapons. Other navies were similarly unprepared, even though every major navy had

16625-515: Was more economical and better suited to convoy protection, it was too late; coupled to incompetent doctrine and organization, it could have had little effect in any case. Late in the war, the Japanese Army and Navy used Magnetic Anomaly Detector (MAD) gear in aircraft to locate shallow submerged submarines. The Japanese Army also developed two small aircraft carriers and Ka-1 autogyro aircraft for use in an antisubmarine warfare role, while

16758-531: Was not without controversy, the RAF had declared its preference for an all- Chinook fleet; also, Boeing allegedly offered cheaper terms for the Chinook. RAF deliveries began in 1997; RN deliveries started the following year. Following the merger of Westland and Agusta to form AgustaWestland in 2000, there was no need for the separate EHI entity; the EH101 was formally re-branded as the AW101 in 2007. By April 2009, more than 180 AW101s had been sold worldwide;

16891-436: Was officially presented to the press on 6 December 1999. Italy accepted delivery of the 21st AW101, configured for anti-submarine warfare, on 4 August 2009. In total 22 AW101 helicopters have been delivered to the Italian Navy. Italian AW101s have operated from a variety of ships and have seen service overseas; in 2009 the Italian Navy used its AW101 fleet as executive transports for visiting heads of state and officials during

17024-434: Was seen as a factor in the 1993 Canadian federal election . The order was cancelled by the new Liberal government in 1993 resulting in a $ 470 million cancellation fee. Several pre-production aircraft were assembled during the late 1980s and early 1990s. The first pre-production aircraft had its first flight powered by General Electric CT7-2A engines on 9 October 1987. Flight tests were suspended for six months following

17157-644: Was set to retire in 2016, leaving the Navy operating a combination of the Wildcat and Merlin. 846 NAS reformed with ex-RAF Merlin HC3s on 30 September 2014; 845 NAS followed on 9 July 2015. On 25 May 2018, the first of 25 converted Royal Marines Commando Merlin Mk4/4A were delivered to Royal Naval Air Station (RNAS) Yeovilton. In July 2020, the Merlin HM2 and HC4/4A helicopters were planned to be in service until 2029 and 2030, respectively. On 11 June 2021, it

17290-605: Was strongly influenced by the duel between HMS  Venturer and U-864 . A significant detection aid that has continued in service is the Magnetic Anomaly Detector (MAD), a passive device. First used during the Second World War, MAD uses the Earth's magnetosphere as a standard, detecting anomalies caused by large metallic vessels, such as submarines. Modern MAD arrays are usually contained in

17423-643: Was the acquisition of six AW101s from Denmark in 2007; designated Merlin HC3A , these were assigned to the RAF, allowing Merlins to be deployed in Afghanistan . The HC3A is used for training and not for frontline operations due to various configuration differences. In December 2007, a second Merlin squadron, No. 78 Squadron was formed at RAF Benson. In 2009, five Merlin Mk3s were operating in Afghanistan, transporting troops and supplies. The deployment to Afghanistan

17556-454: Was to commence the assembly of some AW101s later on. By September 2013 AgustaWestland was in the process of acquiring civil certification for the AW101; prospective customers include offshore oil platform operators and VIP clients. As of February 2014, AgustaWestland was considering adapting the AW101 as a heavyweight unmanned aerial vehicle , it is proposed that in this configuration an AW101 could be optionally crewed. On 7 June 2010, it

17689-600: Was undetectable by "Metox", in sufficient numbers to yield good results. Eventually the "Naxos" radar detector was fielded that could detect 10-cm wavelength radar, but it had a very short range and only gave a U-boat limited time to dive. Between 1943 and 1945, radar equipped aircraft would account for the bulk of Allied kills against U-boats. Allied anti-submarine tactics developed to defend convoys (the Royal Navy 's preferred method), aggressively hunt down U-boats (the U.S. Navy approach), and to divert vulnerable or valuable ships away from known U-boat concentrations. During

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