Countering the MANPAD threat consistently challenges industry’s design and development teams.
One of the most unpredictable and terrifying asymmetric threats to military fixed-wing aircraft and rotorcraft revolves around Man-Portable Air Defence Systems, or MANPADS. These low-cost, light-weight, infrared surface-to-air missile systems are small in size, highly mobile, easy to employ, and exceptionally difficult to detect – all of which makes them incredibly lethal.
Numerous countries around the world manufacture MANPADS, and although these systems are tightly controlled, they are prevalent across the globe. Additionally, the features that make MANPADS suitable for soldiers also makes them attractive to those with nefarious intent. Collectively, these aspects make countering the MANPADS threat an incredibly important priority for militaries around the world.
The MANPADS threat
The first development of a rudimentary MANPADS dates back to the 1940s where unguided rockets were used. MANPADS became more refined and much more lethal in the 1960s when systems began to use heat-seeking infrared (IR) missiles which guide themselves by zeroing in on a target’s infrared heat signature. Unlike radar guided missiles, infrared guided missiles are undetectable until launched.
Simply stated, a MANPADS consists of a launcher tube with a gripstock, a sight assembly, and a battery/coolant unit. Inside the launcher tube is a single infrared radiation homing (heat-seeking) guided missile that requires no control from the gunner after firing. The missile itself is comprised of three main sections: guidance, warhead, and propulsion.
The first MANPADS of significance in the United States was the General Dynamics FIM-43 Redeye; however the most well known system today is the Raytheon FIM-92 Stinger weapon system.
In Russia, the first generation MANPADS was the KB Mashinostroyeniya (KBM) 9K32 Strela family (NATO code names: SA-7 Grail, SA-14 Gremlin). This system was superseded by the KBM 9K310 Igla family (NATO code names: SA-16 Gimlet, SA-18 Grouse, SA-24 Grinch); and since 2014 they have been superseded by the KBM 9K333 Verba (NATO code name: SA-25). The Verba’s primary new feature is its missile’s three channel multispectral optical seeker head which works on ultraviolet, near infrared, and mid-infrared wavelengths.
The United States and Russia are the primary countries that build or license these systems for manufacture, however other nations that have developed their own versions, whether they be copies or indigenous designs.
Depending on model and variant, MANPADS IR missiles have a range of 500 meters (546 yards) to 8km (5 miles), and can reach an altitude of 16,000 feet (4,876m) . Many newer MANPADS now employ advanced microprocessors for improved tracking ability, and improved infrared counter countermeasures (IRCCM) capability. Threats are also evolving to incorporate imaging technology – visible energy – to ‘look’ for aircraft.
Designs to counter MANPADS
An important aspect to countering infrared threats, be it MANPADS or others, is to suppress or reduce an aircraft’s infrared signature. This is particularly important in low flying military aircraft like helicopters. Aerospace engineers who design military aircraft are very cognisant of this, and go to great lengths to suppress an IR signature – this often entails masking an IR source, or dissipating IR energy.
Naturally, the greatest IR signature emanating from an aircraft is from its engines, which are difficult to mask without the expense of performance, considerations of maintainability, or a host of other factors. A prime example of an aircraft design which embodies engine masking is the Northrop Grumman B-2 Stealth Bomber.
Dissipating IR energy is usually done through the addition of IR suppressors, or by using heat exchangers. IR suppressors reduce exhaust temperatures by shielding a hot engine from view and mixing it with ambient air – as seen in the Boeing AH-64 Apache; and/or by ‘bending’ the exhaust with the aid of a cowl – as is seen in the Leonardo AW159 Wildcat.
Heat exchangers on the other hand, use fluid or materials to absorb and exchange heat. The Lockheed Martin F-35 Lightning II makes use of fuel to dissipate thermal loads generated by the aircraft’s avionics suite and sub-systems.
Masking and dissipating techniques are helpful methods to reduce an aircraft’s IR signature, however one can’t cheat physics altogether as any aircraft moving through the air will emanate IR energy by way of friction, which newer guidance sections on IR missiles are adept at distinguishing.
Never enough knowledge
The old adage of ‘knowledge is power’ holds very true when considering mission safety and success, therefore a key element to every sortie is a comprehensive pre-mission brief. This fact cannot be understated as unit/squadron intelligence officers are key in disseminating knowledge on threats in a given theater of operations.
If MANPADS threats are known to be present, the easiest way to counter them is to avoid the area entirely. If a mission necessitates entering a threat area, then the next best option is to fly above the MANPADS threat envelope, which safely means above 20,000ft (6,096m). This of course is a moot point when an aircraft needs to takeoff or land.
As noted previously, the problem with MANPADS are they are small, concealable, and very portable. These factors mean that a single person with a MANPADS can pop up and engage an aircraft virtually anywhere. If flying in an area where MANPADS are suspected, pilots can use the earth’s topography to mask their aircraft. Nap-of-the-earth flying is a type of very low-altitude flight used by military aircraft to avoid enemy detection in a high-threat environment. During nap-of-the-earth flight, geographical features like valleys and folds in terrain are used as cover and concealment.
High-speed flight at low-altitude is another way to evade a MANPADS threat since a MANPADS operator needs to visually identify and track a target before engaging it. If an aircraft flies low and fast, the pilot effectively reduces the time in which a MANPADS operator can develop a tracking solution before the aircraft is out of view.
Interestingly, nap-of-the-earth flying has gone out of favor in recent years due to the profilerence of small arms fire, as has been seen in Iraq and Afghanistan. Because of this, militaries around the world are flying their aircraft higher, and are therefore turning to technology to counter the growing MANPADS threat.
The most common countermeasure against infrared missiles is flares. First-generation MANPADS missiles, often referenced to as ‘tail-chase’ missiles, were often defeated by the use of flares which burn hotter than an aircraft’s engine/exhaust, thereby decoying infrared heat-seeking missiles. Flares are still used to great effect today, however aircraft carry a finite number which is a critical limitation once stores are expended.
Later generation IR missiles employ enhanced guidance section section cooling which increases their acuity for heat sources on aircraft. IR missile capability has been further enhanced by single or multiple detectors in the guidance section which have the ability to recognize and reject flares dispensed from aircraft. Newer infrared seekers also tend to have multi-spectral sensitivity tailored to more closely match the emissions of airplanes, and are also incorporating enhanced IRCCM.
“Because countermeasures have become so effective, threat manufacturers seek to add different ways to counter the countermeasures. What you’re seeing in the field of countermeasures is a constant cat and mouse game of cyclical capabilities which constantly evolves, and is usually driven by the pace of geopolitical events,” said Tom Kirkpatrick, a business development manager for BAE Systems Survivability, Targeting, and Sensing Solutions. “In today’s world, they [MANPADS] are a very present threat so the technology has ramped up in the last few years as we see threats proliferate, and we see countermeasures advancing to counter those.”
One of the most prolific infrared countermeasures (IRCM) systems fitted to helicopters and small aircraft today is the “always-on” BAE Systems AN/ALQ-144 IR Countermeasures Set which provides protection against infrared missiles over a wide wavelength range. The system has an IR source which is surrounded by a large cylindrical mechanical shutter that modulates the infrared output, producing a pulsing pattern which serves to decoy IR missiles. The newest variant, the AN/ALQ-144C has an increased cooling and air filtering capability which provides greater mission versatility and readiness. There are multiple configurations available to complement small to medium signature aircraft. The system is fitted to one of the newest maritime patrol helicopters in the world, the Sikorsky CH-148 Cyclone.
The AN/ALQ-144 IR Countermeasures Set may operate independently, or improve survivability in combination with a missile warning system and flares. In the case of the Cyclone, the ALQ-144 works in conjunction with the AN/ALE-47 Countermeasures Dispensing System (CMDS).
To date, over 8,000 AN/ALQ-144 IR Countermeasures Sets have been delivered to the U.S. military and 23 other nations.
Modern MANPADS missiles can be launched from any aspect to a target, and can travel at speeds of 570 meters per second (Mach 1.7), so the ability for a pilot to detect a launch is extremely remote, and evading them is typically beyond human reaction time.
In order to address the time/speed/distance problem inherent in the MANPADS threat, companies have developed advanced infrared countermeasures systems which utilise electro-optical systems which automatically detect missile launches from the distinct thermal emission of a missile’s rocket motor, and then automatically deploy both thermal expendables (flares) and directable lasers to defeat – commonly known as Directional Infrared Countermeasures Systems (DIRCM).
BAE Systems is the current provider of a suite of systems for a U.S. Army program of record to protect its fleet of CH-47 Chinook helicopters. This suite of systems is comprised of the BAE Systems AN/AAR-57 Common Missile Warning System (CMWS) which provides advanced missile warning and hostile fire detection for rotary and fixed-wing aircraft. The system uses electro-optic missile sensors (EOMS) paired with an electronic control unit (ECU) to automatically detect a wide range of missile and hostile fire threats. The system is linked to the AN/ALE-47 CMDS and the AN/ALQ-212 ATIRCM (Advanced Threat Infrared Countermeasure) directional infrared countermeasures system.
Once an IR missile launch is detected by the CMWS, the system automatically hands-off to the CMDS to dispense flares as needed, and it also provides a spatial cue to the ATIRCM system which acquires the missile and tracks the trajectory with a high-precision tracking sensor. The ATIRCM infrared jam head then fires a multi-band laser beam directly into the missile seeker, causing the missile to steer away from the aircraft.
“One of BAE Systems’ expertise lies in laser technology. The laser that we use in our ATIRCM system is called the multi-band laser. These bands are all columnated into one single beam, so it’s not just a single wavelength – we’re putting out multiple wavelengths in one beam that we’re directing towards the threat. That provides us with greater capacity to defeat infrared missiles,” said Kirkpatrick.
In 2015, the U.S. DoD approved ATIRCM for export. Now fielded in over 10 countries, BAE Systems has delivered and installed more than 2,000 CMWS units on over 30 different platforms with a recorded reliability four times the requirement. Since 2005, CMWS has logged more than 3 million combat theatre flight hours with the U.S. Army, saving dozens of aircraft and hundreds of lives. The most recently developed, third-generation CMWS technology integrates hostile fire indication with missile warning into one unit. This enables high performance in complex missile, small arms, and rocket propelled grenade scenarios.
CIRCM for US Army Aviation
DIRCM system technology is constantly evolving, and part of that effort is focused on reducing size and weight. The U.S. Army’s new programme of record for laser-based aircraft missile defence is the CIRCM (Common Infrared Countermeasures) programme, which is intended to develop a lightweight, low-cost and modular infrared protection system for U.S. helicopters and light fixed-wing aircraft.
Northrop Grumman was selected to deliver the CIRCM programme. CIRCM is part of a suite of infrared countermeasures that utilises the CMWS and an Improved Countermeasure Dispenser (ICMD) for flares and chaff. According to the company, their CIRCM solution uses a compact ECLIPSE pointer/tracker, a lightweight commercial-off-the-shelf processor, and advanced Quantum Cascade Laser (QCL) technology for greater reliability and scalability. Partnered with Northrop Grumman is Leonardo MW, Northrop Grumman’s IRCM partner for more than 15 years, and Daylight Solutions, an innovator in QCL-based laser technology.
“We have a very robust program and we are constantly looking at better techniques and tactics and hardware that allows us to stay ahead of the threat in terms of defeating it,” said Phil Louden, director, Business Development with Northrop Grumman’s Mission Systems. “We’re installed on 1,500 aircraft, our platforms are in combat every day, and we’ve had no missile hits and no loss of aircraft with our system. We get the benefit of all that performance and data feedback that allows us to continue to advance and develop techniques that are more effective against current threats and anticipated future threats.”
Implementing new technologies is never easy, and the CIRCM program is facing challenges. According to a 26 April 2017 U.S. Department of Defense Inspector General (DoD IG) report titled: “The Army Needs to More Effectively Prepare for Production of the Common Infrared Countermeasure System,” the report states that Army management did not adequately define firm system capability requirements (what the system must do to meet its mission). The Army also prepared requirements documents, which communicated system capabilities, and implemented a test plan that does not require CIRCM to demonstrate minimum required system reliability. The DoD IG report adds that CIRCM is demonstrating just 70 percent (150 hours) of the 214 hours mean time between operational mission failures needed to meet the minimum system reliability requirement.
Asian Military Review posed questions to Northrop Grumman about the status of the CIRCM program, and received the following reply via e-mail: “Northrop Grumman remains committed to delivering this critical technology to the Army. Contractor flight testing, live fire, guided weapons evaluation facility (GWEF), and recent reliability characterization have all shown very positive results. Our team is working closely with the Army to achieve programme milestones within Acquisition Program Baseline parameters and provide this important countermeasure protection to our warfighters.”
In other counter-IR efforts, Northrop Grumman has developed the Guardian system for use by larger legacy aircraft. The fully automatic system provides 360° protection against a wide range of missile threats. The system includes an ultraviolet missile warning sensor and a multiband laser pointer/ tracker. The low-profile system is contained almost entirely in a single pod that mounts to the underside of the fuselage and protrudes just 18 inches into the air stream. Guardian is the role fit version of the Northrop Grumman AN/AAQ-24(V) LAIRCM (Large Aircraft Infrared Countermeasure) system which in use today with the U.S. Air Force, U.S. Navy and other military aircraft around the world.
There are many other DIRCMs on the market, as well as new systems which are being developed. In the United Kingdom, the Ministry of Defence (MoD) – Defence Science and Technology Laboratory (Dstl) has contracted Leonardo and Thales to demonstrate an infrared protection system. The companies are currently engaged in development activities to bring together two of their most advanced products: Thales’s ‘Elix-IR’ Threat Warning System and Leonardo’s ‘Miysis’ DIRCM system. Under the contracts, funding from the UK MoD will support lab-based and field trials of the integrated system in early 2018 and help evaluate its use for current and future UK air platform protection.
It is clear that DIRCM systems are the current gold standard in the cat and mouse battle to defeat MANPADS. DIRCM systems are undergoing a period of design and enhancement to stay ahead of this lethal and ever-evolving threat.