BAE Hot Brick infrared jammerSukhoi Su-27 shoots off false heat targetsC-130 Hercules deploys flares, sometimes called angel flares because of their characteristic pattern
An infrared countermeasure (IRCM) is a device designed to protect aircraft from infrared homing ("heat seeking") missiles by confusing the missiles' infrared guidance system so that they miss their target (electronic countermeasure). Heat-seeking missiles were responsible for about 80% of air losses in Operation Desert Storm. The most common method of infrared countermeasure is deploying flares, as the heat produced by the flares creates hundreds of targets for the missile.
An infrared sensor that is sensitive to heat, such as emitted from an aircraft engine, is included on missiles launched by man-portable air-defense systems (MANPADS). Using a steering system, the missile is programmed to home in on the infrared heat signal. Because they are portable, MANPADS missiles have a limited range, burning out a few seconds after launch.
Countermeasure systems are usually integrated into the aircraft, such as in the fuselage, wing, or nose of the aircraft, or fixed to an outer portion of the aircraft. Depending on where the systems are mounted, they can increase drag, reducing flight performance and increasing operating cost.
Because they are expensive, such countermeasure systems have been seldom used, primarily on military aircraft. Much time and money is spent on testing, maintaining, servicing, and upgrading systems. These procedures require that the aircraft are grounded for a period of time.
History
Conventional man-portable air defense systems (MANPADS)-launched missiles include an infrared sensor that is sensitive to heat, for example the heat emitted from an aircraft engine. The missile is programmed to home in on the infrared heat signal using a steering system. Using a rotating reticle as a shutter for the sensor, the incoming heat signal is modulated, and, using the modulated signal, an on-board processor performs the calculations necessary to steer the missile to its target. Owing to its portable size, MANPADS missiles have a limited range, and a burn time of a few seconds from launch to extinguishing.
In recent years, missile guidance systems have become increasingly sophisticated, and, as a result, there are a number of different types of missiles in existence. In some, the missile is outfitted with multiple sensors that detect infrared radiation at multiple wavelengths, using reticles that are encoded at different patterns. In view of the threat, various countermeasure techniques have become popular. A missile warning system scans the region for rocket launch signals, such as the infrared or ultraviolet signature of a rocket tail. Upon the detection of a missile launch, various countermeasure systems are activated. In one example, hot flares or chaff are released from the aircraft to confuse the infrared or radar system of the launched missile.
Other approaches broadcast light energy to confuse the missile infrared sensors. In one example, light energy emitted by non-coherent flashlamps is directed toward the missile sensors, to confuse them and render them ineffective ("jamming"). IR missiles are vulnerable to high-powered IR carrier signals which blind the IR detector of the incoming IR missile. In addition, IR missiles are vulnerable to lower-powered IR carrier signals that are modulated using certain modulating signals that confuse its tracking system and cause the tracking system to track a false target. Conventional countermeasures to an IR missile threat include jamming systems which confuse or blind the IR missile using either IR lamps and/or IR lasers. These jamming systems transmit either a high-powered IR carrier signal to blind the IR detector of the incoming IR missile or transmit a lower-powered IR carrier signal modulated with a modulating signal to confuse the IR detector of the incoming missile.
As infrared missiles are increasingly cheap and simple, they have been increasingly dangerous. By one estimate more than 500,000 shoulder-fired surface-to-air missiles exist and are available on the worldwide market. The lethality and proliferation of IR surface-to-air missiles (SAMs) was demonstrated during the Desert Storm conflict, as approximately 80% of US fixed-wing aircraft losses in Desert Storm were from ground-based, Iraqi defensive systems using IR SAMS. Both IR SAMS and IR air-to-air missiles have seekers with improved Counter-Countermeasures (CCM) capabilities that seriously degrade the effectiveness of current expendable decoys. Man Portable Air Defense Systems (MANPADS) are the most serious threat to large, predictable, and slow flying air mobility aircraft. These systems are lethal, affordable, easy to use, and difficult to track and counter. According to a 1997 CIA Report, MANPADS have proliferated worldwide, accounting for over 400 casualties in 27 incidents involving civil aircraft over the previous 19 years. This proliferation has forced air mobility planners to frequently select less than optimal mission routes due to lack of defensive systems on airlift aircraft.
Infrared missile seekers of the first generation typically used a spinning reticle with a pattern on it that modulates infrared energy before it falls on a detector (A mode of operation called Spin scan). The patterns used differ from seeker to seeker, but the principle is the same. By modulating the signal, the steering logic can tell where the infrared source of energy is relative to the missile direction of flight. In more recent designs the missile optics will rotate and the rotating image is projected on a stationary reticle (a mode called "conical scan") or stationary set of detectors which generates a pulsed signal which is processed by the tracking logic.
Most shoulder-launched (MANPADS) systems use this type of seeker, as do many air defense systems and air-to-air missiles (for example the AIM-9L).
Principles
An ALQ-144 modulated IRCM jammer
Infrared seekers are designed to track a strong source of infrared radiation (usually a jet engine in modern military aircraft). IRCM systems are based on a source of infrared radiation with a higher intensity than the target. When this is received by a missile, it may overwhelm the original infrared signal from the aircraft and provide incorrect steering cues to the missile. The missile may then deviate from the target, breaking lock. Once an infrared seeker breaks lock (they typically have a field of view of 1–2 degrees), they rarely reacquire the target. By using flares, the target can cause the confused seeker to lock onto a new infrared source that is rapidly moving away from the true target.
The modulated radiation from the IRCM generates a false tracking command in the seeker tracking logic. The effectiveness of the IRCM is determined by the ratio of jamming intensity to the target (or signal) intensity. This ratio is usually called the J/S ratio. Another important factor is the modulation frequencies which should be close to the actual missile frequencies. For spin scan missiles the required J/S is quite low but for newer missiles the required J/S is quite high requiring a directional source of radiation (DIRCM).[1]
Flares create infrared targets with a much stronger signature than the aircraft's engines. The flares provide false targets that cause the missile to make incorrect steering decisions. The missile will rapidly break off a target lock-on.
DIRCM, or Directional Infrared Countermeasures, avoid this potential drawback by mounting the energy source on a movable turret (much like a FLIR turret). They only operate when cued by a missile warning system of a missile launch, and use the missile plume to accurately aim at the missile seeker. The modulated signal can then be directed at the seeker, and the modulation scheme can be cycled to try to defeat a variety of seekers. Countermeasure success depends on a threat's tracking techniques and requires a proper analysis of the missile's capabilities. Defeating advanced tracking systems requires a higher level of DIRCM power. Issues of Laser Safety are also taken into account.
Israel has announced a program to develop a system called Multi Spectral Infrared Countermeasure (MUSIC) that will similarly use active lasers instead of flares to protect civilian aircraft against MANPADs.[2] The US Army is deploying a similar system to protect its helicopters.[3]
The Department of the Navy Large Aircraft Countermeasures (DoN LAIRCM) by Northrop Grumman provides infrared threat protection for U.S. Marine Corps CH-53E, CH-46E and CH-53D platforms.[4]
BAE Systems' AN/ALQ-212 advanced threat infrared countermeasures (ATIRCM) - part of a directable infrared countermeasures suite - is fielded on U.S. Army CH-47 Chinook helicopters. The suite provides protection against an array of threats, including all infrared threat bands. The AN/ALQ-212 incorporates one or more infrared jam heads to counter multiple missile attacks.
At IDEX 2013, Finmeccanica Company, Selex ES launched its Miysis DIRCM, suitable for all airborne platforms, rotary and fixed wing, large and small.
ITT's CIRCM fitted to US Army UH-60 during test exercises
Common Infrared Countermeasures (CIRCM) is a laser-based IR countermeasure against current and future IR threat systems for the US Army rotorcraft and fixed wing platforms and US Navy and US Air Force rotorcraft platforms. Systems by BAE Systems, ITT Defense and Information Solutions, Northrop Grumman and Raytheon were under consideration. In August 2015, Northrop Grumman won the contract.[5]
Flight Guard by Israel Aerospace Industries, used in military and civilian aircraft (gain the nickname of "Live Saver" due to history of success in saving air vehicles during battles at several countries), but banned at several European airports. According to defense sources in Israel, the European ban is "odd and based mostly on a misunderstanding."[8]
The 9K32 Strela-2 is a light-weight, shoulder-fired, surface-to-air missile system. It is designed to target aircraft at low altitudes with passive infrared-homing guidance and destroy them with a high-explosive warhead.
The Missile Transportable Anti-aérien Léger, commonly called Mistral, is a French infrared homing short range air defense system manufactured by MBDA France. Based on the French SATCP, the development of the portable system later to become the Mistral began in 1974. The first version of the system was introduced in 1988 (S1), the second in 1997, and the third in 2018.
An air-to-air missile (AAM) is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fueled but sometimes liquid fueled. Ramjet engines, as used on the Meteor, are emerging as propulsion that will enable future medium- to long-range missiles to maintain higher average speed across their engagement envelope.
An electronic countermeasure (ECM) is an electrical or electronic device designed to trick or deceive radar, sonar, or other detection systems, like infrared (IR) or lasers. It may be used both offensively and defensively to deny targeting information to an enemy. The system may make many separate targets appear to the enemy, or make the real target appear to disappear or move about randomly. It is used effectively to protect aircraft from guided missiles. Most air forces use ECM to protect their aircraft from attack. It has also been deployed by military ships and recently on some advanced tanks to fool laser/IR guided missiles. It is frequently coupled with stealth advances so that the ECM systems have an easier job. Offensive ECM often takes the form of jamming. Self-protecting (defensive) ECM includes using blip enhancement and jamming of missile terminal homers.
Directional Infrared Counter Measures (DIRCM) are a class of anti-missile systems produced to protect aircraft from infrared homing missiles, primarily MANPADS and similar simple systems.
Man-portable air-defense systems are portable surface-to-air missiles. They are guided weapons and are a threat to low-flying aircraft, especially helicopters.
The 9K38 Igla is a Russian/Soviet man-portable infrared homing surface-to-air missile (SAM) system. A simplified, earlier version is known as the 9K310 Igla-1, and the latest variant is the 9K338 Igla-S.
Infrared homing is a passive weapon guidance system which uses the infrared (IR) light emission from a target to track and follow it seamlessly. Missiles which use infrared seeking are often referred to as "heat-seekers" since infrared is radiated strongly by hot bodies. Many objects such as people, vehicle engines and aircraft generate and emit heat and so are especially visible in the infrared wavelengths of light compared to objects in the background.
The AN/ALQ-144, AN/ALQ-147, and AN/ALQ-157 are US infra-red guided missile countermeasure devices (IRCM). They were developed by Sanders Associates in the 1970s to counter the threat of infra-red guided surface to air missiles like the 9K32 Strela-2. While decoy flares were effective at jamming first generation infra-red guided missiles, each flare was only effective for a short period. If an aircraft needed to loiter over a high risk area or was flying slowly, it would require a large number of flares to decoy any missile fired at it. The IRCM provided constant protection against infra-red guided missiles.
A flare or decoy flare is an aerial infrared countermeasure used by an aircraft to counter an infrared homing ("heat-seeking") surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust. The aim is to make the infrared-guided missile seek out the heat signature from the flare rather than the aircraft's engines.
Civil Aircraft Missile Protection System (CAMPS) is an infrared countermeasure against infrared-homed anti-aircraft missiles, specifically designed to defend civilian aircraft flying under 15,000 feet (4,600 m) against MANPADS.
Flight Guard is an Elta Systems Ltd's brand name for a family of airborne systems for protecting civilian aircraft against man-portable air-defense systems.
The Northrop Grumman Guardian is a passive anti-missile countermeasure system designed specifically to protect commercial airliners from shoulder-launched missiles, using directed infrared countermeasures (DIRCM) technology.
Project CHLOE is a research and development program of the Department of Homeland Security (DHS) to explore technology-based unmanned aerial vehicle (UAV) mounted defenses for airports and airliners against the threat of infrared man-portable anti-aircraft missiles. The project's name refers to the character Chloe O'Brian on the television show 24, which is Former Homeland Security Secretary Michael Chertoff's favorite show.
A missile approach warningsystem (MAW) is part of the avionics package on some military aircraft. A sensor detects attacking missiles. Its automatic warning cues the pilot to make a defensive maneuver and deploy the available countermeasures to disrupt missile tracking.
The Vigilant Eagle Airport Protection System is a proposed directed-energy weapon under development by the U.S. military under a Defense Department contract with Raytheon. It would create an invisible microwave dome around an airport that could block missiles heading toward incoming and outgoing aircraft.
The AN/ALE-47 Airborne Countermeasures Dispenser System is used to protect military aircraft from incoming radar and infrared homing missiles. It works by dispensing flares or chaff. It is used on a variety of U.S. Air Force, Navy, and Army aircraft, as well as in other militaries.
The AN/AAR-47 Missile Warning System is a Missile Approach Warning system used on slow moving aircraft such as helicopters and military transport aircraft to notify the pilot of threats and to trigger the aircraft's countermeasures systems. Its main users are the U.S. Army, Navy and Air Force, but is also operated by other countries. Originally developed by Loral, and later dual-source procured from Loral Infrared & Imaging Systems and Honeywell Electro-Optics Div., both in Lexington, MA, it has been a product of Alliant Techsystems (ATK) since 2002. 100 to 300 sets have been manufactured per annum.
CIRCM, the Common Infrared Countermeasures program, is a United States Army initiative intended to develop a lightweight, low-cost and modular laser-based infrared protection system for U.S. helicopters and light fixed-wing aircraft. The technology will primarily provide defense against shoulder-fired, heat-seeking missiles, or MANPADS. The program is being developed to replace older suites such as the Advanced Threat Infrared Countermeasures (ATIRCM).
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