Wednesday, February 1, 2012
Militaries look for new ways to detect and defend against land-based man portable air defense systems
Undeniably one of the most present and most concealed threats on the battlefield today remains the shoulder-launched, heat-seeking surface-to-air missiles, or Man Portable Air Defense Systems (MANPADS), a lightweight and proliferating weapon with a low acquisition cost. The names of such systems are well-known the Russian-made 9K38 Igla, U.S. FIM-43 Red Eye or FIM-92 Stinger, British Blowpipe, French Mistral, Swedish RBS 70, and even Egyptian-made Falcon Eye or Chinese-made (HN-5) copies of the infamous Soviet 9K32M Strela (NATO SA-7b).
Intended for short-range air defense, MANPADS have also landed in the hands of uncontrolled groups or terrorist organizations, accounting for some dramatic deadly attacks on civilian transport aircraft. These 4-foot long, 20-pound missiles, capable of reaching Mach 2 in 5 seconds and with an average lethal range of just a few miles, were at first historically responsible, in the hands of the mujahideen, for the destruction of many Soviet airlifters, as well as transport and attack helicopters during the Soviet war in Afghanistan. More recently, infrared countermeasure systems have been designed to defeat both surface-to-air and air-to-air missiles by detecting both the ultraviolet (UV) and infrared (IR) radiation from the missile exhaust trail and then initiating proper responses. Their efficiency is very high provided they are linked to a very reactive warning system.
In contrast with radar-guided missiles, IR-guided missiles are very difficult to spot and locate as they gain on an aircraft. They have no radar signature, and are generally fired from the rear, directly toward the jet pipe of an aircraft or the hot exhaust of a turbine. In most cases, during combat, pilots have to rely on their wingmen to spot the missile’s characteristic smoke trail and alert them. Since MANPADS are inherently far shorter-legged in distance and altitude range than their radar-guided counterparts, good situational awareness of altitude and potential threats continues to be a very effective defense against MANPADS. Luckily, much more advanced electro-optical systems as developed during the past two decades can now detect missile launches automatically from the very distinct emissions of a missile’s rocket motor, both in IR and UV bands.
Every other year since 1991, NATO has organized a series of two live exercises, designated MACE, focusing on expensive electromagnetic (EM) self-defense systems, and EMBOW, focusing only on ways to counter heat-seeking (IR) missiles fired from the ground. For the most recent EMBOW exercise, held from Sept. 18 to Oct. 12, 2011, the stress was put on the extended use of new generation decoy flares jettisoned at low- and mid-altitudes, with added fine-tuning systems in the pipe to deceive further shoulder-launched heat-seeking missiles. The event took place at Cazaux air base, on the Atlantic coast of France, and saw participation from Belgium, Canada, the Czech Republic, Denmark, Germany, Italy, Norway, France the Netherlands, Poland, Spain, Turkey, United Kingdom, United States, Australia and New Zealand.
Performed in a highly instrumented test zone and orchestrated by NATO’s SG2/Aerospace Capability Group 3 on “Electronic Warfare and Survivability,” EMBOW allowed aviators to test, under live and monitored conditions, the capacity of their aircraft to evade infrared-guided surface-to-air missiles, from basic MANPADS to more advanced surface to air short-range systems (SHORADS). Any noticed problem or malfunction was then funneled, in a second move, back to the industry for updating and improvements.
EMBOW XIII placed a strong priority on how to enhance or optimize the self-protection systems of NATO aircraft currently participating in overseas expeditionary missions: fighters, airlifters and helicopters alike. U.S. airplanes and rotorcraft from other NATO nations have paid, since 2002 in Iraq and Afghanistan, a heavy toll to the insurgents, while air operations over Libya have proved in combat the value of the different EW systems developed by the European companies for their current generation fixed-wing aircraft and rotorcraft.
In the present day combat theater, if adequate IR flares are enough to protect against evolved seekers, new inventions are now being developed to deceive a new generation of shoulder-launched infrared missiles. This is particularly important for newer seekers, dubbed SG4 by NATO, which are able to discriminate easily between jet pipes and flaming decoys. This aptitude was demonstrated in a confidential video shown to NATO-screened defense media in Cazaux by engineer Isabelle Lecuyer, the woman in charge of aircraft self-protection systems with DGA, the French Military Procurement Agency. In this dramatic live video, a Mirage 2000 dropping traditional flares could not succeed in evading the “lock-on” of a late generation IR tracker now being developed by MBDA, giving the sword a clean edge over the shield.
First-generation IR missile seekers typically used a spinning reticule with a pattern on it modulating IR energy, which is then fed onto a detector. The patterns used differ from company to company, from nation to nation, and from seeker to seeker, but the basic principle remains the same. By modulating the signal, the steering logic can tell where the IR energy source is relative to the missile direction of flight. All first-generation (1G) seekers from the 1960s work that way. In more recent designs (2G), those from the 1970s, the missile optics will rotate and a rotating image is projected on a stationary reticule (a mode called conical scan) or stationary set of detectors that generates a pulsed signal which is then processed by the tracking logic.
Most MANPADS from the past century use this type of seeker, as do many short-range air defense systems and air-to-air missiles. Still these missiles can be often lured by adequate IR decoys. But it is a different story with the seekers of latest generation missiles (3G) which use IR differential ecartometry and shape recognition, color sensitive discriminating systems (4G), staring-plane array detecting photons at particular wavelengths, now under development. Luckily, in terms of proliferation, only the 1Gs and 2Gs have been identified in the hands of insurgent groups. But for how long?
Nevertheless, new countermeasures are being designed in order to protect aircraft further against the MANPADS. Among the most promising is the Directional Infrared Counter Measure system (DIRCM), a system principally produced by Northrop Grumman, ITT Corp. and BAE Systems in the United States, and by Elbit and Rafael in Israel. Thales, Terma, Saab, Selex Galileo and Indra in Europe are also working on new DIRCMs, as is the very proactive Russian industry. However, this technology is expensive and is far from mature. Further developments will be needed before such systems are fielded in great numbers.
In 2011, European manufacturers of electronic warfare equipment took good advantage of EMBOW XIII to test current system, as well as prototypes of future systems, during some 100 “live firing” sorties from Cazaux air base performed over the DGA Biscarosse test site and its extensive network of radars and trajectography equipment.
EADS subsidiary Cassidian and Indra of Spain used a CASA 212 testbed from France’s DGA to test a new DIRCM designed for the self-protection of high-value transport aircraft. Dubbed Manta (for MANpads Threat Avoidance), this very bulky multi-spectral multi-band high-energy laser-based system (developed by Spain’s National Institute of Aerospace Technology, and produced in partnership with Rosoboronexport of Russia), is capable of countering several MANPADS launched simultaneously from short distances. It is intended to equip the Airbus Military A400M at a later stage.
For the EMBOW XIII evaluation, Indra’s Manta was linked to selected sensors from Cassidian’s AN/AAR-60 MILDS (MIssile Launch Detection System) missile warning system (MWS), which are already used on many NATO tactical helicopters, including the NHI NH90, Eurocopter EC665 Tiger, Alenia A129 Mangusta or Sikorsky UH-60 Black Hawk.
More advanced than conventional flare-based IR countermeasure systems, a standard DIRCM is a compact system designed to provide mission-vulnerable aircraft like strategic airlifters and helicopters with increased protection from common battlefield IR threats. The term DIRCM is used as a generic moniker to describe any complex IRCM system that tracks and directs energy toward the menace. The pioneer Northrop Grumman AN/AAQ-24 Nemesis, actually the world’s only operationally known deployed laser DIRCM system, consists of a missile warning system (AN/AAR-54), an integration unit, a processor, and belly and side swiveling laser turrets designed to blind and lure incoming heat-seeking missiles with pinpoint precision. The AN/AAQ-24 has been setting the trend, although this hi-tech system only appeared in the wake of the Sanders AN/ALQ-132 omnidirectional IRCM system used during the U.S. war in Vietnam, fuel fired by a flash lamp system, hence its nickname “Discolight.” It was superseded by the AN/ALQ-144 more adapted to attack helicopter self-protection and the AN/ALQ-157 used for larger helicopters and aircraft but always in combination with IR flare dispensers.
Its latest iteration is the BAE Systems AN/ALQ-212(V) or ATIRCM/CMWS, currently fielded on U.S. Army later model CH-47 Chinook helicopters. This infrared countermeasures suite provides passive warning of missile approach using the AN/AAR-57 tri-service common missile warning system, which detects the missile, rejects any false alarms and cues the onboard IR jamming system’s jam head to the missile’s location. When the jam head finds the missile with its IR tracking system, it emits a high-energy beam of infrared energy to defeat the missile’s infrared seeker, thus acting somewhat like a flare but without dust or smoke emissions. The AN/ALQ-212(V) incorporates one or more infrared jam heads to counter multiple missile attacks.
ITT is also developing a cascade laser Common IRCM (CIRCM) for the U.S. Army.
Companies in Russia are also developing a similar system. The standard Russian optronic self-defense system remains the L166 family of omnidirectional IRCM “cans.” Manufactured by Zenit and designated L166C1 or L166V1AE, they are intended to provide effective protection of aircraft against guided IR homing missiles like the AIM-9 Sidewinder, MIM-72 Chaparral, FIM-92 Stinger or the Russian Strela-2M. The modulated IR flux formed by the L166 baseline system makes up the jamming noise inside the missile’s “track loop” and exploits its guidance system to steer it away from the emitting aircraft. The hit probability is then decreased practically to zero.
In the same category, but more advanced, the Jam Air system, designed by Israeli company Rafael, is another airborne jamming system with proven operational effectiveness. The system uses a fast, high-power jamming turret integrated to a very sensitive missile warning system, the Guitar 350. Jam Air can function as a stand-alone system or combined with a flare dispenser. The list is certainly incomplete, but all are based on directed IR hot-electric source or laser high-energy beams.
If early versions of the AN/AAQ-24 Nemesis used an arc lamp to generate jamming signals, newer versions use a YAG-based laser diode pump system, which guarantees maximum peak energy at all times. AAQ-24 systems are fitted to or scheduled to be installed as standard on first line U.S. Air Force C-17 and MC-130 airlifters, and CV-22 and CH-53E rotorcraft, but also on many NATO countries helicopters (AW 101, Sea King, Lynx) and key strategic aircraft like the new Airbus A330 MRTT or various presidential transports.
Nemesis is also the basis for the Northrop Grumman Guardian system, marketed for commercial aircraft as CAMPS (Civil Aircraft Missile Protection System) only after the basic open-architecture CIRCM became fully developed with the parent company. Pending the large-scale completion of ICAO tests on the viability of such options, Guardian, Elta’s Flight Guard or Saab Avitronics entry will likely be fitted to many commercial carriers in the near future. So will the Large Aircraft Infrared Counter Measure system (LAIRCM) and LAIRCM-Lite which is a strict C-17 program that uses a combination of laser jammers and flares due to the limited availability of some LAIRCM components.
Elbit Systems, of Israel, has also developed a DIRCM system for the protection of civilian aircraft against MANPADS called the Multi-Spectral Infrared Countermeasure (MUSIC), a nacelle-mounted, fully automatic system that detects, acquires, tracks and counters an incoming missile. It has been installed on governmental or VIP aircraft thus providing protection against MANPADS, including the most recent ones, some of which were simulated during EMBOW XIII, always in combination with droppable IR flares for improved all-aspect protection.
One of the main drawbacks of standard IRCM jammers is that they broadcast — a bright source of infrared. If the modulation of the signal happens to be ineffective against a particular seeker system, then the IRCM will, in turn, enhance the ability of the missile to track the aircraft it is supposed to protect. Even if the aircrews typically brief about potential threats prior to a sortie and choose an IRCM modulation that will be effective against any likely MANPADS menace, the droppable infrared flare cartridge remains by far the cheapest and most reliable all-round protection at all times, particularly when used in numbers and in appropriate computer-controlled launch sequences in high-peril environments.