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Defending the attacker.

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Air combat has virtually ceased to exist outside of training exercises, but the proliferation of surface-to-air guided missiles has ensured that aircraft are still shot down. In the past quarter-century, over three quarters of shoot-downs have been by low-cost, widely available infrared homing, man-portable air-defence systems (Manpads).

The severity of this threat is believed to have been a major factor in the US Army's decision not to deploy the Boeing AH-64 Apache to Kosovo in 1999. There are suggestions that the threat may push military helicopter cruise altitudes over southwest Asia to much higher levels.

It would be difficult to overstate the importance of defensive aids suites for many manned aircraft and the larger drones. This also applies to commercial transports and business jets, although accounts of around 30 civil aircraft having been shot down by Sams since 1970 (with over 1000 lives lost) include at least two major non-Manpads accidents: the US Navy's destruction by SM-2 of an Iran Air A300 in 1988 (290 lost) and the Ukrainian Navy's destruction by S-200 (SA-5) of a Siberia Airlines Tu-154 in 2001 (77 lost).

The majority of Mapads available to resistance forces may now be time-expired, and their single-shot kill-probability may be small, but hundreds of thousands have been manufactured (around 10,000/yr in the 1980s), and the danger is real.

However, defensive aids suites are only one factor in minimising aircraft attrition due to enemy actions. Signature reduction, passive defences (armour protection and self-sealing tanks), the support of other airborne and ground-based assets and risk-reduction tactics must also be addressed.

Regarding tactics, it is arguable that the Lockheed Martin F-117A stealth aircraft would not have been shot down (in 1998 by an upgraded Serbian Almaz-Antey S-125 Pechora or SA-3), had its missions not been scheduled like a train service.

In the context of an optically directed Manpads attack, the first defensive steps are to sense the missile launch and exhaust plume. When Sams were introduced in Vietnam, launch detection depended initially on operating aircraft in pairs or fours, giving mutual visual cover. Airframe-mounted sensors later provided automatic indication of such attacks, although with more false warnings.

RWR

Early warning of possible attack may be provided by detecting an active enemy radar at (or in the vicinity of) the firing point. The aircraft's radar warning receiver (RWR) may then provide the location of the source and nature of the emission, having compared it with a threat 'library' of hostile and friendly radars. Such an RWR may be described as an electronic support measures (ESM) system.

However, networked fighter aircraft and ground defences are able to fire medium- and long-range missiles without prior transmissions from the launch site, thus minimising warning to their targets.

American RWRs fall in the Pentagon's ALR or APR (A = piloted aircraft, L = countermeasures, R = radar, P = passive) designation series. Examples include the Northrop Grumman ALR-67(V) and -67(V)2 Advanced Special Receiver series, of which over 1600 units have been manufactured, primarily for US Navy fighters and attack aircraft. The Raytheon ALR-67(V)3 is used on the F/A-18E/F and has been chosen for the Canadian CF-188 Hornet. The same company's ALR-69A(V), the first all-digital RWR, is on the US Air Force A-10, AC-130, F-16 and MC-130. The Northrop Grumman ALR-93 equips Greek F-16s. The BAE Systems ALR-94 is the ESM system for the F-22. Most US Army helicopters and the V-22 series have the Litton-developed APR-39 family, now manufactured by Lockheed Martin and Northrop Grumman.

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European RWRs include the Elettronica ELT/156 fitted to the MB-339CD and A129, and the ELT/158 used on AMX and some Mirage 2000s. EADS Defence Electronics and Indra are jointly developing the ALR-400 for the A400M. The Selex Sky Guardian 2000 is used on British AH64Ds and EH101s. Israeli RWRs are exemplified by the Elisra SPS-1000(V)5, selected for Portugal's F-16s.

The Russian RWR most commonly used appears to be the SPO-15 Beryoza (Birch), which replaces the earlier Sirena-3. The Su-30MKI has the Mk 2 version of Tarang (Spectrum in Sanskrit), developed by India's Defence Avionics Research Establishment and produced by Bharat Electronics.

MAW

American missile approach warning (Maw) sensors fall in the Pentagon's AAR (AAR = piloted aircraft, infrared, passive) series, such as the Alliant Techsystems AAR-47 (also made by Lockheed Martin) on the C-130 and C-17 and the Northrop Grumman AAR-54 family, which is used on the AC/MC-130 and ten other aircraft types. The latter company's Mims (Multi-Imaging Multi-Spectral) two-colour Maw sensor has been developed as a replacement for the AAR-54.

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The Lockheed Martin AAR-56 Missile Launch Detector equips the F-22, and the company is competing with Northrop Grumman to supply the NexGen MWS (missile warning system) for US Air Force transports and tankers. The BAE Systems AAR-57(V) Common Missile Warning System equips aircraft of all the US armed services. Over 1000 have been delivered and production is running at over 40 per month.

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The Elisra Paws (Passive Airborne Warning System) equips Israeli AH-64Ds, and the Paws-2 is a joint development with Raytheon for the F-16. The IAI-Elta EL/M-2160 Missile Approach Warning System employs a pulse-Doppler sensor to detect and track incoming threats. Pulse-Doppler is also used by the MWS-20 Damien, which is produced by Thales Airborne Systems and employed in combination with the same company's TDS-TA radar warning system in French Air Force transports. The latest version of MBDA's DDM (Detecteur de Depart Missiles) series, which was developed jointly with Sagem and initially equipped the Mirage 2000, is the DDM-NG (previously Samir) for the Rafale F3.

The Milds (Missile Launch Detection System) developed by EADS senses ultraviolet emissions and is in production for the NH90 and Tiger helicopters. It is marketed by Litton as the AAR-60 and was chosen (together with the Thales MWS-20) by L-3 Communications for its Wipps (Widebody Integrated Platform Protection System) and the second-generation Caps2 (Commercial Airliner Protection System--Two). The Milds-F is a joint development with Terma for pylon mounting on fighters.

Malaysia's Su-30MKM has a Saab Avitronics Maw-300 missile approach warning system, which is also used on Swiss Cougars and Swedish Super Pumas.

Countermeasures Dispensers

Saab Avitronics produces a variety of advanced countermeasures dispensers, notably the Bol family, integrated into missile launchers. Over 2500 examples of the BAE Systems ALE-47 (ALE = piloted aircraft, countermeasures, ejection/release) dispenser have been manufactured for fixed- and rotary-wing aircraft operated by more than 20 countries. The Raytheon Comet, with the dimensions and weight of the Lau-68 rocket pod, dispenses IR wafers (by Alloy Surfaces), providing continuous protection for up to 30 minutes.

Other leaders in this field include MBDA, which makes the Eclair-M for the Mirage 2000, and the Saphir-M for the NH90 and Tiger, and is developing the Saphir-400 for the A400M. Alkan makes the Elips series of dispensers for helicopters and light aircraft, the Cads series for combat aircraft and the Spirit series for large aircraft. Israel's IMI Rocket Systems Division produces the Samp-60/120/240 countermeasures dispenser system family.

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Expendables

Anti-radar chaff (initially code-named 'Window') was introduced by Britain in 1943 to reduce bomber attrition. Infrared decoy flares were used by American aircraft over Vietnam from around 1970. Dispensing is often combined with an evasive manoeuvre, and sometimes with a power reduction to restrict emissions.

Chaff originally took the form of bundles of aluminium strips that were cut to equal half the wavelengths they were to reflect. Today, aluminium-coated glass filaments of around 25 microns diameter are widely used. A single Chemring RR170 cartridge can generate a radar cross-section of 700 square metres at a frequency of three GHz.

Magnesium-based pyrotechnic flares were highly effective against the first generation of infrared seekers. These detected short wavelengths and could be decoyed easily, by man-made devices, the sun and brightly illuminated cloud. However, dual-wavelength seekers enabled missiles to discriminate aircraft from simple decoys.

The traditional high-visibility burning flare, emitting bright light and smoke, also has the drawback of attracting attention to the target. In the 1990s the Pennsylvania-based Alloy Surfaces invented a pyrophoric (or 'pyroforic') flare, virtually invisible to the human eye. Beginning in 2000, the company (which, like the Tennessee-based Kilgore Flares, is part of the Chemring Group) manufactured a range of Special Materials Decoys (SMD) with pyrophoric wafers that oxidise spontaneously in air, emitting infrared while visually covert.

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The SMD range included the MJU-27/B (now superseded by the MJU-27A/B and -49/B) for US Navy aircraft, the -50/B for US Air Force transports and the -51/B for the service's combat aircraft. Production is currently ramping up to 80,000 units per month.

Pyrophoric flares reportedly employ iron platelets with a porous aluminium coating. Whereas pyrotechnic flares contain both a fuel and an oxidant, pyrophoric flares rely on atmospheric oxygen, and their emission thus varies with altitude.

The corresponding US Army effort is the Advanced Infrared Countermeasures Munition (Aircmm) for helicopter use, which in 2003 led to Alloy Surfaces' M211 and Alliant Techsystems' M212 flares. The Aircmm series was introduced on special operations aircraft; US Army MH-60s and MH-47s and later on US Air Force HH-60s and AC-130s.

Another 'invisible' or 'black' flare is the IMI-RSD product used in IAI/Elta's Flight Guard self-protection system fitted to some El AI airliners and Israeli Air Force aircraft. Flares produced by IMI include the Multi-blu, which houses two or three flares into a standard 1 x 1 x 8-inch module. IMI also produces the FG-3, a 1 x 1 x 8-inch unit for the F-16 and various helicopters, and the FG-6, a 1 x 2 x 8-inch unit for the F-15.

Wallop Defence Systems produces flares for a wide range of aircraft. The older MTV (Magnesium/Teflon/Viton) series, developed to counter missiles such as the SA-7, has been followed by Spectral flares to decoy dual-band missiles. However, MTV flares remain a useful element in defeating missiles of unknown type.

Even if a flare produces the correct emission, it does not necessarily begin emitting on the incoming missile's line-of-sight, and its velocity falls rapidly. Many Russian combat aircraft employ upward ejection, which (with evasive manoeuvres) may increase effectiveness.

Some new flares egress forwards. BAE Systems' MJU-47/B ASTE (Advanced Strategic-Tactical Expendable) Kinetic Decoy Rocket and MJU-48/B Two-Part Expendable Decoy are both rocket-powered, and the Chemring website refers to a 'thrusted' flare.

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Towed Decoys

Another way to give the decoy an aircraft-like velocity is to tow it. The first operational towed radar decoy was the GEC-Marconi Aerial, used by British RAF Nimrods in the 1991 Gulf War. It was later applied to the Tornado.

First deployed on US Air Force F-16s in 1996, the Raytheon Ale-50 towed decoy is also used on the B-1B and the US Navy F/A-18E/E It receives electrical power via the tow cable, and repeats incoming radar signals. Almost 25,000 have been ordered.

The BAE Systems ALE-55 fibre-optic towed decoy is used on the AC-130 and MC-130, transmitting range-deception signals from an ALQ-214 jammer on the parent aircraft.

The Raytheon ALQ-184(V)9 ECM pod combines radar jamming and ALE-50 towed decoy facilities.

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Radar Jammers

There are so many radar jammers that space restrictions allow mention of only a few examples. The US designation ALQ-applies; the 'Q' indicating 'special or combination'.

The Northrop Grumman ALQ-131 has been used on many US Air Force fixed-wing aircraft and is currently undergoing a mid-life upgrade. The ITT ALQ-136 equips many helicopters and low-speed fixed-wing aircraft. The Northrop Grumman/ITT ALQ-165 has been applied to the F-16 and F/A-18. The Raytheon ALQ-184 (an upgraded ALQ-119) is used on the A-10, F-15 and F-16, and the company's ALQ-187 has been installed on some F-16s.

The ITT ALQ-211 integrated RWR/jammer, as used on Ussocom's CV-22s, MH-47s and MH-60s, has become virtually standard fit on export Block 50/52 F-16s, with orders from Chile, Oman, Pakistan and Poland. These F-16s carry the ALQ-211(V)4 internally, but ITT has teamed with Meggitt to develop a jammer pod with the same aerodynamic and mass properties as the already-certified ALQ-131, for which it is marketed as a replacement. This ALQ-211 (V)9 pod will interface with Raytheon's ALR-69 RWR and Terma's ALQ-213 controller. ITT's ALQ-214(V)2 jammer equips the F/A-18E/F.

The IAI-Elta EL/L-8222 jammer is used on Israeli F-15s and Indian Su30MKIs, while the EL/L-8212 is for lighter aircraft. Italy's Elettronica ELT/568(V) has been selected for the MiG-35 proposed to India. The Terma ALQ-213(V) electronic warfare management system was originally developed for the F-16, but over 1600 have now been delivered for a variety of applications.

Infrared Jammers

Early infrared-homing missile seekers had a rotating reticle or 'chopper', with spiral slots that transmitted the incoming energy to the sensor in pulses, the frequency-variation and phase of which indicated the angular position of its target. Such systems can be made to generate false guidance demands by a jammer emitting energy pulses of varying frequency.

Examples of infrared jammers include Russia's L166S1 Sukhogruz, which is fitted at the tail of the Su-25T/39, and covers a 50[degrees] sector. It is manufactured by the Zagorsk Optical Mechanical Plant and is offered for installation on business jets. The L166B1A version is used on the Mi8/17 and Mi-24.

The BAE Systems ALQ-144 and -147 jammers are fitted to many US helicopters. Around 6000 are used in 19 countries. Applications have included Israeli AH-1s, but these are now being given the Rafael Jam Air system. The more powerful Lockheed Martin ALQ-157 (likewise developed by Sanders) is used on some larger helicopters and the C-130 and P-3C.

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Later missiles deleted the chopper in favour of rosette scans and staring arrays, requiring more powerful countermeasures. Fortunately, advances in missile approach warning systems have made possible directed infrared countermeasures (Dircm), which concentrate power to blind the weapon's seeker.

One example is the BAE Systems ALQ-212(V) Advanced Threat IRCM, which includes the AAR-57(V) Common Missile Warning System. The Atircm is operational in Iraq on the fixed-wing aircraft of <<a classified customer>>, according to BAE Systems. The Northrop Grumman AAQ-24(V) Nemesis is now in service on all UK and some US Air Force aircraft in Iraq, using the company's AAR-54(V) warning system, with the Mims as a future alternative.

Those two companies have largely dominated the US Dircm field, but the Raytheon Scorpion has been developed from the Aim-9X missile seeker, and ITT is reportedly working on a rival system.

Diehl BGT Defense, EADS and Thales are collaborating on the Flash Dircm for the A400M. France's Cilas has recently announced the receipt of a DGA contract as part of the latter's Cesam programme to develop a jamming laser to protect future transport aircraft. Spain's Indra is reportedly co-operating with Russian companies on a Dircm for large aircraft.

Elbit Systems' Elop is working with Elettronica on Dircm systems for helicopters and wide-bodied aircraft. Elop is also collaborating with Rafael, to combine technology from their Music and Britening IRCMs. Darpa and the US Air Force Research Laboratory are developing the Medusa system, with a range of applications that includes drones.

Under the US Department of Homeland Security Counter Manpads programme, BAE Systems and Northrop Grumman are competing to equip American airliners with Dircm systems. The BAE Systems JetEye, which is being tested on an American Airlines 767, is derived from the ALQ-212(V). The Northrop Grumman Guardian, based on the AAQ-24(V), is being flown on eleven large aircraft (B-747, MD-10 and MD-11).
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Title Annotation:Aircraft: self-protection
Author:Braybrook, Roy
Publication:Armada International
Date:Dec 1, 2007
Words:2598
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