ATMACA ASCM Boosts the Sub-Strategic Naval Strike Capability of the Turkish Naval Forces

Under the ATMACA Surface-to-Surface Guided Missile Project, which was launched on May 8, 2009 to meet Turkish Naval Forces Command (TNFC)’s requirement for a new generation anti-ship cruise missile (ASCM) with land attack capability through national means and capabilities the last two guided test-firings of the ATMACA missile from the TCG Kınalıada Corvette with a telemetry system and a live warhead was successfully conducted on February 3-4, 2021, off the coast of Sinop in the Black Sea region before its planned delivery in 2021 Q2. These launches were also recorded as the 2nd and 3rd guided test-firings of the ATMACA ASCM from a naval platform.

During the telemetry test performed on February 3rd in the Black Sea, northeast of Sinop, the ATMACA ASCM was fired from a 4-cell launcher (similar to the Mk-141) placed on the port side of the TCG Kınalıada Corvette and successfully scored a hit on the Roketsan made stationary floating target platform, which imitates a surface target. On February 4, 2021, the second launch test was carried out against a similar stationary floating target platform with the ATMACA ASCM fitted with a live warhead, and this time, the target was also destroyed successfully. With the last live firing test, the effectiveness of the ATMACA missile's warhead was also tested for the first time on the missile. Both launches from the TCG Kınalıada Corvette were monitored live by the test measurement equipment at the Sinop Missile Test Range (such as radar systems and high-speed cameras that can measure the missile's trajectory and speed) and from the air by a UAV (Call Sign: Cenah 2) using the Star Safire 380 HLD FLIR payload. President of Defense Industries Prof. İsmail DEMİR announced the tests on his official social media account and congratulated all staff involved for the successful test. “Our first indigenous anti-ship missile ATMACA successfully destroyed the target after it was fired from our national ship TCG Kınalıada. I congratulate everyone who contributed. Godspeed to our Heroic Navy!" President Prof. DEMİR also shared a short video of the test-fires performed on February 3rd and February 4th between 14:00 and 14:30. In the footage recorded by a UAV flying at an altitude of 18,129ft, the passive ranging maneuver performed by the ATMACA missile at the terminal stage before hitting the platform type stationary floating target can be clearly seen (during the firing test conducted on February 4th).

TCG Kınalıada Corvette, which performed the launches, sailed to the Black Sea by passing through the Bosporus at around 21:40 on the evening of January 23, 2021. In fact, I was expecting the decommissioned TCG IŞIN (A-589) to be used as the target ship at the live firing test. Prior to the firing test planned for August 30 last year, the decommissioned IŞIN was pulled to Sinop by TCG Alemdar (A-582) on August 27, 2020, to be used as the target ship. However, due to an undisclosed reason, this test was canceled at the last minute.

The first controlled flight test with the ATMACA Anti-Ship Missile was performed in 2016. Later in parallel with the maturation of the design and the product, three different guided firing tests were conducted with the prototypes of the ATMACA Surface-to-Surface Guided Missile (I believe guided test missiles were equipped with dummy warheads, not with live warheads) in 2019, in May, September 18th, and November 3rd, respectively, in which different features and attack concepts/profiles were tested. While the previous firing tests were carried out toward the Black Sea from a land-based launcher at the Sinop Missile Test Range, the first Naval Launch Test was conducted with the ATMACA Anti-Ship Missile on the morning of November 3rd, 2019. The guided firing tests using prototype missiles without live warheads were carried out against a stationary floating net target fitted with a radar reflector (orange object). Within the scope of the ATMACA Surface-to-Surface Missile Project, three guided firing tests were conducted at the Sinop Missile Test Range in 2020, on July 1st, September 25th (previously stated as September 28th), and December 18th, respectively. Thus, ATMACA passed the first product qualification test by successfully hitting the targets. In the 17th issue of Roketsan Magazine, published in July 2020, it was stated that during the guided firing test carried out from the Sinop Missile Test Range toward the Black Sea on July 1st, 2020, the ATMACA Guided Missile performed all its functions correctly and approached the target 200+ km away with the sea-skimming mode and successfully hit the target by attacking with a pop-up maneuver (it has been claimed that the target was deployed at the furthest distance to date at 220km). Since multiple waypoints are defined instead of a straight-line during flight/firing tests, a route similar to a diamond is followed in the NOTAM test area. As each waypoint (depending on its angle) reduces the total range of the missile from 4 nm (nautical miles) to 17 nm, for example, when two waypoints are defined, the total distance traveled is actually around 60 nm even though the missile cover a 75 nm distance. Since a diamond flight pattern has been defined for the guided flight test, the ATMACA missile must have followed at least 4 or 5 waypoints, which means that the total range is reduced by an average of 60-70km. Technically, since the ATMACA missile cannot follow so many waypoints and strike from the maximum range, either the announced 220km is the direct flight distance to the target or the maximum range of the ATMACA missile in actuality reaches 280-300km.

However, in the video shared by the SSB, it was seen that the ATMACA missile skimmed the surface and approached the target from a very low altitude (only a few meters above the water level) and fell into the sea immediately after hitting the radar reflector on the floating target (possibly due to the maximum range). The guided flight test on July 1st, 2020, also has great importance in terms of being the first flight test in which the ATMACA missile engaged a new target by updating its mission in-flight via the Data Link. According to the article on page 8 of the 17th issue of Roketsan Magazine, within the scope of the aforementioned guided flight test, where the ATMACA missile is aimed to successfully follow the flight route with the help of its inertial navigation system (INS) and hit the target, the ATMACA missile, which performs pre-launch mission planning and firing with its Fire Control System, was directed to a new target with the mission update transmitted over the data link during the flight (however, no information was shared in the article if the data link used during the test is a KEMENT Data Link). The ATMACA ASCM is one step ahead of other anti-ship guided missiles in the market with this feature and has proven that it is ready to serve as the protector of Blue Homeland, considering the images of it scoring a direct hit with perfect accuracy recorded by the cameras on the target.

On August 30th, 2020, another ATMACA Anti-Ship Missile launch test was planned. In this context, a NOTAM was issued between August 29th and September 5th, 2020, restricting an area off Sinop by land and sea for missile firing, and the decommissioned TCG IŞIN (A-589) was pulled to the Black Sea to be used as the target ship. However, due to an undisclosed reason, this test was canceled at the last minute. 

On September 25th, 2020, in an electronic warfare environment scenario mimicking real combat conditions with electronic and GPS jamming, a guided firing test was carried out with the ATMACA Anti-Ship Missile toward the Black Sea from a land-based 4-cell launcher, similar to the Mk-141 which was placed at the Sinop Missile Test Range. In accordance with the scenario, the ATMACA missile successfully hit the surface test target during the test with its onboard Inertial Navigation System (INS) and GPS-free limited navigation support. President of Defense Industries Prof. İsmail DEMİR described this test as the penultimate firing test of the ATMACA missile. At the press breakfast held at Roketsan's Lalahan facilities on September 29th, 2020, Roketsan Chairman of the Board Faruk YİĞİT, Roketsan CEO Murat İKİNCİ, and President of Defense Industries Prof. İsmail DEMİR stated that the project is nearing completion and they expected the serial production activities to start in the near future. During the "Evaluation of 2020 and 2021 Projection Meeting" held on January 11th, 2021, the President of Defense Industries Prof. İsmail DEMİR announced that the first deliveries under Turkey's first national Anti-Ship Missile ATMACA and AKYA National Heavyweight Torpedo Projects would begin in 2021. In addition, Roketsan CEO Murat İKİNCİ gave technical information about the firing test at the press breakfast where Defence Turkey Magazine was also present and said: "This test was actually based on a scenario involving the test of ATMACA under the most challenging conditions. It was able to find and hit the surface target precisely from quite a considerable distance with only its own internal inertial navigation (INS) system, completely independent of GPS. This was an indication that ATMACA was able to hit the target with its very limited navigation capability even in environments where Electronic Warfare was very intense!”

ATMACA ASCM Project

The €80 million contract of the ATMACA ASCM Development Project was signed on May 8th, 2009, and entered into force on October 14th, 2009. The number of missiles to be procured at that time was planned to be 100 according to the SSB, and the first delivery was expected to start on December 31st, 2016. 

The first test-firing activities with the ATMACA Guided Missile (I think Ballistic Test Missiles were used) were carried out in 2014 by the Main Contractor Roketsan, after the production of the first prototypes and the completion of the laboratory tests. In the second flight test campaign, which was carried out in the summer of 2015, the problems in the first tests were mostly eliminated.

In the design of guided missile systems, test and evaluation activities have a very important place in terms of providing the necessary data for the system design, revealing to what extent the design meets the requirements, and giving feedback for further design improvements. The main test activities used in the missile systems design are Wind Tunnel Tests, Hardware-in-the-Loop Tests, and Flight Tests. 

During the flight tests conducted with real missiles, data-acquisition systems are installed on the missile to collect information about the missile's flight characteristics. These data collection systems generally consist of RF-based telemetry systems. In some cases, certain data-acquisition systems that are designed to withstand the high-speed missile impact can also be used to keep the flight data intact.

Radar systems and high-speed cameras that can measure the trajectory and velocity of the missile are also used in the launch tests. The missile prototypes used in guided missile development projects change in parallel with the development of the design process. In the early stages of the project, Ballistic Test Missiles (BTM) are used to verify the missile’s ballistic and aerodynamic characteristics. Subsequently, Controlled Test Missiles (CTM) are used to test the missile's stabilization, autopilot, and control algorithms. Next, Guided Test Missiles (GTM) are used to verify the missile's guidance algorithms and its terminal guidance system. The telemetry system used in the BTM, CTM, and GTM prototypes is usually located in the modular test seekers mounted instead of the missile's warhead. The prototype missiles, which are used to verify the warhead's effectiveness, are equipped with live warheads.

Under the ATMACA Surface-to-Surface Guided Missile Project, the first controlled/guided flight tests were carried out in 2016 (I think Controlled Test Missiles are used). Under the Prototype Production Phase, I believe that around 30 ATMACA ASCMs were produced for flight/firing tests and qualification activities. Domestic companies and institutions such as Aselsan (Ku-Band Active RF Seeker, Fire Control System, Missile Computer and Power Distribution Unit), ArMerKom (Fire Control System and Operator Console prototypes), and Femsan (brushless direct current motors for control surfaces) also took part in the project. The prototype ATMACA missiles used a modified version of the variable-speed (the speed can be changed in flight depending on the mission profile) TR40 Turbojet Engine specifically built for Turkey by SAFRAN Power Units (formerly Microturbo) under the agreement signed in the summer of 2013. The Serial Production Contract for the ATMACA Anti-Ship Guided Missile, which proved itself with the firing tests, was signed between the SSB and the main contractor Roketsan on October 29, 2018.

Currently, Low-Rate Initial Production (LRIP) Phase studies are continuing in the project, and the first serial production ATMACA ASCMs (powered by spare TR40 engines), were planned to be delivered to the Turkish Navy during the second quarter of 2021. Initially, a total of 64 ATMACA missiles (32+32) were expected to be supplied under the LRIP Phase for use in İ-Class (İSTİF) Frigates. However, when the delivery date of the TCG İstanbul Frigate was delayed from 2021 to 2023, a decision was made to integrate the ATMACA ASCM into the ADA Class Corvettes equipped with the ADVENT Combat Management System (CMS), and a contract modification was issued in this context. Since the ATMACA missile will also be integrated into TCG Kınalıada and then TCG Burgazada (ADVENT CMS retrofit process is expected to be completed in 2020) Corvettes, additional missile production is expected. The TCG Kınalıada Corvette, which is equipped with ADVENT CMS with Network Enabled Capability and Integrated Data Capability, does not have a separate operator console (AN/SWG-1A) for the Harpoon Anti-Ship Missile, and the launching/firing functions of the ATMACA and Harpoon missiles can be performed from all operator consoles in the Combat Information Center (CIC). Similarly, TCG Burgazada Corvette, which had GENESİS CMS before being retrofitted with the ADVENT CMS, also does not include the AN/SWG-1A Harpoon Weapon System Console; however, there are two small cabinets placed under a desk in the CIC, and other functions of the Harpoon console are embedded in GENESIS CMS software.

Deliveries under the LRIP Phase were expected to begin in 2019 and to have been completed in 2020, but this calendar was postponed due to additional missile requirements and embargoes. According to the information we received, due to the implicit embargo imposed by the French Government because of the political tension between the two countries, there are some problems with the procurement of the TR40 Turbojet Engines required for the Serial Production Phase, which also delays the production and delivery schedule. As a matter of fact, although the SSB's official Twitter account announced that the ATMACA missile was planned to be put into service in the second half of 2020, the delivery schedule was updated as 2021 at the 'Evaluation of 2020 and 2021 Projection Meeting' held on January 11, 2021. In the 18th issue of Roketsan Magazine published in January 2021, Roketsan Chairman of the Board Prof. Dr. Faruk YİĞİT announced that they will start delivering ATMACA missiles to the Turkish Navy as of the second quarter of 2021. 

Additionally, the delivery schedule within the scope of the indigenous design KTJ-3200 Turbojet Engine Program, which will replace the TR40 engines, was unfortunately delayed. The two operational KTJ-3200 Turbojet Engine prototypes were scheduled to be delivered to the SSB in June 2016 for flight tests (previously announced as April 2016), but this schedule was later subsequently updated as late 2017, first half 2018, late 2018, and then early 2019. Lastly, speaking at the panel held on December 26, 2020, during the 8th Turkey Innovation Week, Kale Group Vice Chairman and President of Technical Division, Osman OKYAY, announced that the first engine would be delivered in mid-January or at the end of January at the latest, following the completion of the qualification tests. However, as of March 3, 2021, neither the SSB nor Kale Group has shared any information regarding engine deliveries. OKYAY also emphasized that only a single part of the engine, which consists of around 300 parts, was procured from a foreign country. The KTJ-3200 will replace the TR40 engines used in both the ATMACA ASCM Project and the Precision-Guided Stand-Off Missile (SOM) Project, which is Turkey's first national Air-Launched Cruise Missile (ALCM) study. During the "Evaluation of 2020 and 2021 Projection Meeting" held at Presidency of Defense Industries, it was stated that the KTJ-3200 Turbojet Engine to be used in SOM and ATMACA Missiles would be delivered for the first time in 2021. 

However, following the delivery, the KTJ-3200 Turbojet Engine, with a thrust capacity of 3,200N (3,2kN/719,3lbf), must first be integrated into SOM and ATMACA missiles through a series of flight and firing tests to qualify this integration process. Although the KTJ-3200 engine has a similar French-style design characteristic just like the TR40, it is not interchangeable with the TR40, and a series of modifications are required to integrate it into both SOM and ATMACA missiles. I predict that this process will continue until the end of 2021 at best. Therefore, if the TR40 engine procurement problem with France cannot be solved, the total production of both ATMACA and SOM Missiles will remain limited (depending on the number of available spare TR40 engines) until the KTJ-3200 engine reaches the serial production/delivery phase and is qualified for these two munitions (currently, a total of 495 SOM Series ALCMs are expected to be produced, including 80 in the first batch and 415 in the second batch). Meanwhile, the SSB also continues negotiations with Ukraine for engine procurement. In a statement he gave to SavunmaSanayiST.com in November 2020, the President of Defense Industries Prof. İsmail DEMİR pointed out that there are enough TR40 engines to continue the Serial Production Phase for a certain period and emphasized that they are also looking for different suppliers for alternative engines. President Prof. DEMİR said, "We are talking with Ukraine in order not to put all our eggs in one basket. On the one hand, we also need to make sure that our own engine is used operationally. We are currently assessing the engine issue from three different angles and continue our activities to provide different solutions and increase our engine's performance. The first is using the existing engine, the second is purchasing engines from Ukraine and even establishing an assembly line in Turkey, and the third is increasing the thrust of our indigenous engine and making engines that will run longer."

According to Roketsan, the high-precision ATMACA missile was indigenously developed to meet the Turkish Navy's operational requirements for Anti-Surface Warfare with its anti-ship and coastal attack capabilities and can be deployed from different surface vessels such as destroyers, frigates, corvettes, and fast attack crafts. ATMACA has a length of 4.8m (5.2m with booster) and weighs around 800kg. I estimate that the ATMACA Guided Missile has a 350mm diameter and a 1.4m wingspan. The ATMACA missile, which is stated to have a low radar cross-section (RCS), can operate in all weather conditions thanks to its Aselsan made Ku-Band active radar (RF) Seeker. With the addition of Meteksan Defence/MilSOFT made ATMACA Data Terminal (ADT), which is developed under the KEMENT-A Phase of the KEMENT Project, in addition to the active RF Seeker + GPS/INS Guidance System and Radar Altimeter, the ATMACA missile will also acquire in-flight Target Update, Re-Attack (new target identification), Re-Target and Mission Abort capabilities via the fully encrypted two-way data link. 

Thanks to its effective range of more than 200 km, the ATMACA guided missile poses a significant threat to targets beyond the line of sight with its 250kg high explosive penetrating warhead. During the flight, the ATMACA missile navigates using the Inertial Navigation System (INS), Global Positioning System (GPS), Barometric Altimeter, and Radar Altimeter and provides the user with the most efficient mission profile with its three-dimensional (3D) Mission Planning capability. The ATMACA missile, which is believed to have a cruise speed of Mach 0.85-Mach 0.95 at the terminal phase, has several operational modes (including Time on Target [ToT], Designated Time on Target [DToT], Simultaneous Time on Target [SToT] and Ripple [Salvo, thanks to ToT capability all the missiles can arrive at the target at roughly the same time] Fire) and attack modes (such as direct attack [sea-skimming], top attack [pop-up maneuver], and re-attack).  Thanks to its advanced navigation equipment, the ATMACA missile can fly in sea-skimming mode at altitudes of 5m and under (I believe that at that altitude, special guidance algorithms and "suppression mode" are used to suppress the radar echo [sea clutter] that can blind the RF Seeker). In the video of the flight test conducted on November 3rd, 2019, it is seen that the ATMACA missile performs evasive maneuvers (first to the left and then to the right) by lowering its cruising altitude considerably at the terminal phase a few nautical miles from the target and passes just a few centimeters over the radar reflector (orange object) on the fixed floating target. It is claimed that the ATMACA missile can withstand 12+G at the terminal phase, and the missile was flying only 93 cm above the sea surface at the time of impact. In a statement he gave in November 2019, President of Defense Industries Prof. İsmail DEMİR pointed out that the unit cost of the ATMACA Surface-to-Surface Guided Missile was under US$500,000.

The KEMENT Project was initiated to domestically develop and produce a fully encrypted two-way tactical data link and its related terminals to provide midcourse guidance capability for SOM ALCM and ATMACA missiles. Within the scope of the KEMENT Project signed with the SSB on January 21st, 2014, Meteksan Defense completed the Factory Acceptance Tests (FAT) in August 2018 and the Field Acceptance Tests in June 2019 (both tests were conducted with the participation of TurAF and SSB representatives). The KEMENT-A Phase covered the development of ATMACA Data Terminal (ADT), Ship Data Terminal (SDT), and Relay Data Terminals (RDT) that can be integrated into relevant platforms, including the ATMACA Surface-to-Surface Guided Missile. However, no information regarding the completion of the KEMENT-A Phase has been publicly disclosed as of February 5th, 2021. Therefore, it is currently not possible to make a clear assessment of whether the system used during the guided flight test conducted on July 1st, 2020, was the ATMACA Data Terminal (ADT) developed under the KEMENT-A Phase.  

The ATMACA Phase II (ATMACA Block II) Project, which I believe was launched in 2019, includes the development of the submarine-launched version of the ATMACA ASCM. The new missile, dubbed the “ATMACA Block II” can be launched from the 533mm diameter torpedo tube of submarines through a special buoyant capsule (Encapsulated ATMACA Block II, like the Encapsulated Harpoon). According to the information I have obtained, ATMACA Block II missiles will be fitted with a more advanced dual-mode (Ku-Band Active RF + IIR) seeker. As far as I know, TÜBİTAK SAGE started working on the IIR seeker to be used in ATMACA a few years ago. On the other hand, there was some news on social media in February 2020 that Ekinoks-AG Company developed a cooled Medium Wavelength Infrared (MWIR) Seeker for the ATMACA Block II Guided Missile. In this case, the ATMACA Block II missile will use a cooled MWIR sensor as its IIR seeker.

The submarine-launched cruise missiles, even with conventional warheads, are accepted as strategic weapons. By integrating ATMACA Block II ASCMs, with land attack capability, into existing submarines, TNF will gain its first ever indigenous submarine-based sub-strategic deep-strike capability before the deployment of GEZGIN SLCMs at MILDEN submarines some time in 2030s.

RGM/UGM-84 Harpoon AShM & the Turkish Naval Forces

US defense giant Boeing product RGM-84 Harpoon series Anti-Ship Missiles (AShMs) with an effective range of 65nm (125km) - 75nm (140km, can reach its target in approximately 6 minutes depending on its speed) and a 225kg (100kg of explosives) warhead currently constitutes the backbone of the Turkish Naval Forces Command's operational requirements for Anti-Surface Warfare with its anti-ship and coastal attack capabilities (Block II version only). It is believed that Boeing has delivered more than 7,500 Harpoon AShMs to be used in over 800 surface and submarine platforms, 14 different aircraft types, and land-based mobile launch platforms in 30 countries.

According to open sources, the Turkish Navy has around 200 RGM-84A (Block 1, no waypoint identification feature, 65nm maximum range, they are now gradually being taken out of service), RGM-84D (Block 1C, can define three waypoints for navigation, 75nm maximum range), RGM-84G (Block 1G, up to 8 waypoints can be defined for navigation, capable of flying in the sea-skimming mode under 50ft [15m], smart seeker with late activation in the terminal phase, re-attack capability - the missile can turn back and attack the target again if misses it), and RGM-84L (Block II, improved target selection, higher probability of scoring a hit on a target than its predecessors, coastal attack capability thanks to its sea clutter and land echo “suppression mode” with GPS, capable of flying in sea-skimming mode below 50ft [15m]), surface-launched anti-ship missiles (fired from ships), as well as about 30 UGM-84C and UGM-84G (fired from submarines) in its inventory currently. The RGM-84A missile canisters have gray nose caps, while the RGM-84D, RGM-84G, and RGM-84L missile canisters have red nose caps. The unit cost of a Harpoon Block II Anti-Ship Guided Missile, which is capable of attacking coastal targets, was given as US$1.2 million in 2007. The versions after Block 1G have been upgraded with the HAFO (High Altitude Fly Out) capability to ensure that the missile can fly over the friendly elements on its flight path without hitting them or avoid the hills on its route while attacking the land targets.

The latest version of the Harpoon Guided Missile is named RGM-84Q-4 Harpoon Block II+ ER (Extended Range). RGM-84Q-4/Block II+ ER, which includes several improvements in the guidance, engine (a new sustainer engine that consumes less fuel), and control sections, has new capabilities such as data link, new GPS/INS equipped with the Selective Availability Anti-Spoofing Module (SAASM), and improved target selectivity. The RGM-84Q-4 Guided Missile, controlled by the Advanced Harpoon Weapon Control System (AHWCS), has a range of 134nm (248km, thanks to the new engine and additional fuel) and a 140kg (300lb) warhead, which is said to be lighter but more lethal than previous versions (500lb in previous versions). Block II models can be upgraded to Block II+ with the Tactical Missile upgrade kits. Deliveries of the RGM-84Q-4 Harpoon Block II+ ER Guided Missile, which achieved Initial Operational Capability (IOC) in 2019, are expected to begin in early 2024.

In June 2007, the U.S. Department of Defense, Defense Security Cooperation Agency (DSCA) notified the U.S. Congress about the sale of 51 Harpoon Block II Guided Missiles (8 in TARTAR launcher configuration for Gabya Class Frigates, 38 in Mk-141 launcher configuration for BARBAROS Class Frigates and ADA Class Corvettes, and 5 of them in Encapsulated/Sub-Harpoon configuration) to Turkey through the FMS channel with an estimated value of US$159 million if all options turn into final orders. However, according to the 2009 Annual Report published by the Ministry of National Defense in 2010, only 25 RGM-84L Harpoon Block II missiles were procured through the FMS channel. The report stated: "According to the contract signed for the procurement of 25 Harpoon Block II Guided Missiles through the FMS channel, nine guided missiles were delivered in 2008, and 16 missiles are expected to be shipped within 2010." Therefore, Harpoon Block II capability is only available on surface platforms, and PREVEZE and GÜR Class Submarines can only use Sub-Harpoon/UGM-84 Guided Missiles (Block 1C and Block 1G). On the other hand, REİS Class Submarines will be able to use Harpoon Block 1C, Block 1G, and Block II guided missiles via the Guided Missile Control System. Although it was claimed that UGM-84L Harpoon Block II would be procured for the GÜR Class in the first half of January 2019, no further information regarding the official order has been mentioned in the national or foreign press, so far. On March 31st, 2017, within the scope of the Deniz Yıldızı (Sea Star) 2017 Exercise organized by the Turkish Naval Forces Command, an RGM-84L Harpoon Block II Ship-Anti-Guided Missile from the TCG Heybeliada Corvette (F-511) and a UGM-84 Sub-Harpoon Guided Missile from the submerged GÜR Class TCG Çanakkale Submarine (S-358) were fired against the target ship, the FFG-7 Class Duncan Frigate.

AShM/ASCMs & "Passive Ranging" Maneuver

Anti-Ship Missiles (AShMs) such as ATMACA, Harpoon, and Exocet increase their thrust in the terminal phase while lowering their altitude and flying close to the water surface (sea-skimming) and start tracking the target by activating their own radars (Active RF Seekers) at a certain distance from the target.

For example, according to open sources, the Harpoon Anti-Ship Guided Missile starts tracking its target with its own radar by activating the Raytheon’s PR-53/DSQ-28 J-Band (10GHz-20GHz) Active RF Seeker (two-axis gimbal) 12nm (starting from RGM-84G/UGM-84G late activation capability gained which allows user to activate RF seeker at less than 12nm distance) away from the target. Again, according to open sources, the MM-40 Exocet Guided Missile activates its Thales product J-Band RF Active Seeker 12-15km away from the target, while the old generation MM-38 Exocet Guided Missile activates its I-Band (8GHz-10GHz) RF Seeker at a maximum distance of 13nm (24km) and starts tracking its target. 

In the terminal phase, the AShM/ASCMs approach surface targets by performing a maneuver called "Passive Ranging" (suddenly moves to the left and then to the right) to check and confirm the position of their prey from different bearings and break the lock of the illumination/fire control radars of the Close-in Weapon Systems (CIWS) deployed on the target ship such as the 20mm Mk-15 Phalanx System, that can only track their target at a very narrow-angle. While the Harpoon AShM performs the maneuver in 2 dimensions, the Exocet MM-40 Block II Guided Missile can perform a 3-Dimensional Passive Ranging maneuver (in other words, while the missile is approaching the target at high speed, it quickly moves left and right, then suddenly increases its altitude, performs a right-left maneuver repeatedly, and decreases its altitude again). When examining the videos of the guided flight tests shared by the SSB, we can say that the ATMACA Guided Missile also has 3D Passive Ranging maneuver capability in the terminal phase. 

The RGM-84 Harpoon AShM attacks its target, either by performing a pop-up maneuver (Block 1A missiles climbs up to 1.800m before diving on the target ship, Block 1B omitted the terminal pop-up; and Block 1C provided a selectable terminal attack mode) a few kilometers away or by directly hitting it in sea-skimming mode. When the Harpoon reaches its maximum altitude during the pop-up maneuver, it makes a move called the "whale body" before diving to the target. This moment is defined as the missile’s weakest moment against the CIWS threat (also when the RCS is highest). It is stated that if a Harpoon AShM could not be hit during the "whale body" movement, it will be extremely tough to hit it later when diving on the ship at high speed from the top. However, hunting down an incoming AShM, which performs evasive maneuvers against the CIWS threat in sea-skimming mode at low altitude, is also not an easy task. According to doctrines, sea-skimming mode is preferred against surface platforms with larger and higher hulls such as corvettes and frigates, while the pop-up maneuver is more preferred against low-height surface platforms such as torpedo boats. This is because the radar/laser altimeters used in AShMs detect echoes from the waves for missile safety in sea-skimming mode and adjust the flight altitude according to the highest wave, not the water level. Therefore, if the sea is calm, the Harpoon missile flies to its target at a 3-4m altitude during the terminal phase in sea-skimming mode, while in a wavy sea where the wave height reaches 3m, it will have to fly at a 6-7m altitude in sea-skimming mode with the guidance of the radar altimeter. In this case, small surface platforms such as torpedo boats and patrol boats with low hull height may be blocked by the waves and cause the AShMs to pass over them, so the "pop-up" attack mode with the top diving maneuver is preferred for such surface targets