by Michael Puttré
Apr. 1, 2001

 

Weapons come along time and again that cause military people to rethink how they go about their business. The breach-loading rifle was such a weapon, as was the machine gun, the all big-gun battleship, the submarine, and, of course, the airplane. Radar changed the equation yet again. And now there is the man-portable air-defense system (MANPADS), popularly conceived as the shoulder-fired, infrared (IR)-seeking missile. Like most revolutionary weapons, the impact is best seen in hindsight. It takes a while, sometimes decades, for the ramifications to sink in.

A search of open literature conducted by BAE Systems (Nashua, NH) has suggested that since 1973, 49 percent of aircraft losses in combat worldwide have been attributed to IR-seeking surface-to-air missiles (SAMs) and another 8 percent to unknown air defenses. By some estimates, 90 percent of all the aircraft lost in combat in the last 15 years have fallen to MANPADS missiles. Rotor & Wings magazine reported that during the 1991 Persian Gulf War, 12 of the 29 American aircraft lost during combat operations (including one US Army AH-64 Apache attack helicopter) are believed to have been shot down by Iraqi SA-16 Iglas (NATO: Gimlet), a recent MANPADS in a long, successful line. This is in spite of the latest IR countermeasures (IRCM) these aircraft carried. Losses of British Tornado fighter-bombers during low-level airfield-cratering strikes in that same conflict caused the Royal Air Force to abandon the tactic.

When the US Army sent Apaches to Albania in support of the NATO air effort and then promptly left them on the ground, they pleaded weather and mechanical problems. Yet Time magazine reported that MANPADS was the real issue: "The brass are worried that the Serbs have moved hundreds of SA-7s [Strela-2 (NATO: Grail)] shoulder-fired missiles toward Albania, lurking in the valleys the Apaches would follow into Kosovo, just waiting for the gunships to cross the frontier. 'The Apaches are MANPADS magnets,' an Army officer says...'We keep asking the Army,' a Joint Staff officer says, 'how many Apaches they think are going to come back.'" The fact that the US Apaches carry expendable IRCM-flares-didn't seem all that comforting to the Pentagon.

The Russians have suffered even more egregiously to MADPADS in their battles with insurgents: famously in Afghanistan as the Soviet Union with losses upwards of 250 aircraft to the Raytheon Stinger, and more recently in a succession of conflicts in the breakaway region of Chechnya in Russia itself. An informal tabulation of Russian military aircraft losses in Chechnya by Al St-Onge of BAE Systems points to the dominance of IR-directed weapons as the primary threat system. St-Onge concludes that of a total of 38 aircraft losses, evidence points to 15 of these falling to MANPADS and 22 to undetermined ground-based air-defense weapons. He estimates that 10 of the 22 "unknown-guidance" losses were caused by IR-directed weapons, leading to a tally of 66 percent of losses attributed to such weapons.

And it's not just the established "great powers" that are getting bloody noses. Emerging powers, such as India, are learning the lesson that air operations can be seriously curtailed or even countered by MANPADS. The brief, sharp conflict between India and Pakistan over the Kargil region of Kashmir in 1999 is a case in point. Rupak Chattopadhyay, editor of Bharat-Rakshak Monitor , a leading Indian defense journal, said the Kargil conflict alerted the Indian Air Force (IAF) to the ever-present dangers of operating in a MANPADS-rich environment. "The IAF lost two fighters, one MiG-27 and one MiG-21M, and an attack helicopter over Kargil," Chattopadyhay reported. "While the MiG-27 was lost because of an engine flameout due to ingestion of smoke and debris, the MiG-21 was lost to a [MANPADS] while searching for the downed MiG-27. It is now appreciated that a lack comprehensive of countermeasures (chaff/flare dispensers) across the MiG-21 fleet contributed significantly to the tragedy. Until Kargil, only the MiG-23BN, a few Jaguars, and a handful of MiG-27s (in addition to the air defense types) were fitted with automated countermeasures. Upgrading the self-defense and jamming capabilities of the rest of the attack fleet has now assumed a sense of urgency and base repair depots have taken on the task of upgrading chaff/flare dispensers."

The interesting detail here is that while Indian air-defense fighters do tend to be equipped with IR countermeasures, presumably for protection against IR-seeking air-to-air missiles, ground-attack aircraft largely were not so equipped. Thus, the aircraft types most likely to face the shoulder-fired threat were not prepared to counter them. It is also worth noting that this relatively inexpensive sting was sufficient to prompt the IAF to reevaluate its countermeasures requirements, and take action. As an aside, one Indian Canberra reconnaissance bomber was hit by MANPADS over Kargil and the pilot managed to land safely, to much acclaim at home. Read about it here: www.bharat-rakshak.com/IAF/History/Kargil/Perumal.html

Worldwide, the conclusion is clear: Shoulder-fired, IR-guided missiles currently represent the most potent practical threat to modern aircraft. The losses say this. The ginger tactics used by the United States and its allies over Yugoslavia and Iraq speak volumes. If the enemy has MANPADS missiles then it isn't safe to fly low enough to use many weapons effectively. Put another way, MANPADS has cracked the shell of air superiority.

This strikes at the heart of the air-land battle doctrine. One key objective of air superiority, some prefer the term supremacy, is to prevent the enemy from moving land forces either to conduct offensive operations or to deploy for effective defense. A modern air force might own the stratosphere, but its possession of that all-important slice of troposphere up to about 10,000 feet is disputed by MANPADS.

What's Going On Here?

Presumably, all of the MANPADS missiles that have been causing so much trouble have been IR-seeking. Presumably, the operators of the aircraft have had access to flares. This begs the question: Are countries not equipping their combat aircraft with flares? Or are they not equipping their aircraft with appropriate warning receivers and relying on crews to deploy flares manually? Or are flares and/or auto-dispensing systems simply not that effective against IR-seeking missiles?

Dr. David Schmeider, senior research scientist at the Electro- Optics, Environment, and Materials Laboratory (EOEML) at Georgia Institute of Technology, says the answer is all of the above. "Sometimes the mission planners are not expecting a MANPADS threat," Schmeider says. "Moreover, not all aircraft are equipped with dispensers and, if they are, they may not be equipped with missile-warning sensors. It is very difficult for the pilot to be able to see and respond to an IR SAM without a warning system. Even if equipped with flares those flares may not have been effective against the CCM [counter-countermeasures] being used by the threat. Nevertheless, many aircraft had simply not been given the combination of equipment needed for this self- protection function when those losses occurred."

Schmeider is on the faculty for a short course entitled "Infrared Countermeasures" at the Georgia Tech campus in Atlanta from May 22-24 (security clearance required). For more information, go to the Georgia Tech Continuing Education Web site at www.conted.gatech.edu.

Protecting aircraft against the shoulder-fired threat is less an exercise in technology than economics: probability and expected-utility. You can't protect every aircraft against every MANPADS (not to mention other threats) in every circumstance. Understanding that specific countermeasures or modes of operation are effective against a finite range of threats, how do you pick the right one for the right platform? For US aircraft, in most instances, each has a classified System Threat Assessment Report (STAR), listing and prioritizing the most likely threats to be faced. CM techniques are developed and specified based on these threat lists.

The primary driver for CM requirements is the aircraft IR signature. Some minimum aircraft signature above the background is usually required for the seeker to acquire and "lock-on" to the target. The variation in signatures from one aircraft to the next can be immense. The Large Aircraft Infrared Countermeasures (LAIRCM) Program Office at Wright Patterson AFB (OH) asserted that if a helicopter (AH-64) has an IR signature of 1, a turboprop transport (C-130) would be 10, a tactical fighter (F-16) would be 35, and a large jet transport (C-17) would be 100. The IR output of a jammer or flare is often specified as a multiple of the aircraft signature and is usually referred to as the Jammer-to-Signature (J/S) or Flare-to-Signature (F/S) Ratio, as appropriate. Sources in the BAE Systems Jam Lab said extensive testing of various MANPADS threats have defined minimum J/S and F/S levels for IRCM to be effective more than 80 percent of the time, which is considered a reasonable threshold for threat exposure.

As Schmeider put it, the strategy for CM selection is driven by such considerations as threat band, CCM sophistication, encounter frequency, and defensive suite affordability. "Ideally one would like to have redundant combinations of the best CM suites on all platforms but that would cost too much," he said. "So an alternative is to keep lightly protected platforms out of range but perhaps equipped with expendables since they are relatively low cost. If your mission requires considerable threat exposure, on the other hand, a more capable suite can often be justified. Here it is important to have good intelligence and as much threat weapon operating knowledge as you can get. If your intel confidence level is high, you can tailor your suite accordingly."

Nevertheless, it is often found that one must defend against multiple generations of missiles with varying levels of CCM sophistication all on the same mission. For low rate encounters one might load out with a "flare cocktail" that would dispense a flare decoy mixture that covers several threat types. High-value platforms, or higher risk missions, can justify a non-expendable jammer complete with missile-warning sensors. Modern IR jammers cover several threat bands and would have some probability of defeating a mix of threat types with lamps equipped with mirrors for protection against attacks from a given quarter.

In other cases it may be found that suitable flares do exist for a broad range of the threat types expected, but protection can still be difficult to achieve. That is because selecting dispenser placement on the aircraft and flare-ejection pattern and timing are tricky and complex problems to solve. These are especially complex problems on large aircraft because of the possibility, especially with MANPADS, that not all of the aircraft will be in the threat seeker's field of view at once. So if you are not careful, you will end up dispensing flares that are either obscured by the platform or simply out of the threat's field of view. If you dispense too soon, the seeker will reacquire the target; if too late, you will fail to get sufficient separation.

"I think you might approach this in terms of 'class of threat' rather than 'specific threat' and aim to defeat the characteristic seeker technology of that MANPADS class," said Dr. Carlo Kopp, a lecturer at School of Computer Science and Software Engineering at Monash University (Melbourne, Australia). "Otherwise, in a 'rainbow threat' environment you might find yourself up against a 'specific threat' which you may not have planned for. The best strategy for dealing with a 'class of threat' is to identify the hard limits to the seeker technology used and then tune your IRCM capability to defeat each and every threat in that class. This is, needless to say, easier said than done, especially as we will see over time increasing amounts of cheap, high-performance digital processing finding its way into MANPADS seekers."

The SA-7 Strela-2 with various upgrades and variants is still one of the most widely deployed MANPADS threats. There are literally tens of thousands of them out there in the world, with regular forces and irregular ones. The good news is that the seeker heads of the SA-7 and many of its variants are well understood. When the missiles appeared in the 1960s and '70s, they had uncooled, spin-scan seekers that basically went after the hottest thing in the sky. Flares were very effective countermeasures against them, particularly since such countermeasures tended to be deployed on helicopters and turbo-prop transports, where the flare was "hotter" than the engine and exhaust. Into the 1980s, SA-14 Strela-3s (NATO: Gremlin) appeared with cooled, conical scanning (con scan) seekers that were better able to discriminate between flares and targets. At the same time, considerable progress was made in the development of more effective flares. That progress has not abated. "It is fair to say that the development of inexpensive pyrophoric materials-materials that self-ignite when exposed to oxygen in the air-is one example of a significant breakthrough," Schmeider said.

These materials burn so slowly they effectively "rust" rapidly rather than burn. The temperatures at which they rust are much lower than the temperatures at which conventional pyrotechnic flares burn. This lower temperature allows them to achieve most of the objectives for covertness, ground-fire prevention, and signature matching. Advanced flares are being developed that also match other important characteristics of aircraft, such as self-propelled decoys that better mimic aircraft kinematics features but still match their infrared signature as well. An aircraft equipped with modern flare dispensers available from any number of manufacturers can consider itself well protected against most widely deployed MANPADS missiles-provided they know a missile is coming or where the threat is so the dispensers can be turned to auto.

Now for the bad news. Flares are not nearly as effective against the second generation of MANPADS missiles, represented by the US Stinger and the SA-16. Such MANPADS have cross-scan or rosette- scan seekers with "two-color" capability that are intended specifically to counter flare signatures. According to many sources, the most capable MANPADS would include the SA-18 Igla-1 (NATO: Grouse), Matra Mistral from France, and the Pakistani Anza Mk II. However, it is difficult to say which is really the most capable because of all the development and upgrade activity thought to be going on. These missiles use advanced scanning in multiple bands (colors) and will almost certainly be equipped with imaging seekers in the very near future.

And now the really bad news. Upgrades can turn even the oldest and most crude missiles into modern threats. "Consider the implications of a block upgrade to an SA-14 that replaces the existing seeker electronics with a 1.2 GHz Pentium IV chip," Kopp said. "What happens to all existing IRCM devised to exploit weaknesses in the electronics of earlier models? Even if flare technology has further scope for development, a good case can be made that increasingly sophisticated MANPADS signal processing will produce kinematics filters capable of rejecting flares even if they are perfectly spectrally matched long-burn devices. Predicting when this point will be reached is fraught with some difficulty, given the incredibly diverse inventory of weapons available, and the diverse spread of variants in use."

The seekers of most IR-guided missiles operate in the middle-IR range (3 µ to 6 µ), which is where hot targets emit most of their radiation. According to Schmeider, the most concern is with those new or upgraded missiles that have detector response in the mid-wave portion of the IR spectrum and that have been given CCM capability. "Mid-wave IR response results in all-aspect launch capability while CCM obviously makes them more difficult to defeat with flares or jammers," Schmeider said. "Mid-wave IR response provides all-aspect capability, because the seeker doesn't have to rely on the hot tail pipe but can see adequate signature from the plume and often from the body. These latter signature sources are more difficult to mask with decoys than were the hot-tailpipe sources that earlier- generation threat missiles exploited."

Here It Comes

Even an aircraft that is equipped with an IR self-protection suite is not totally covered. The problem is lack of situational awareness on two levels. First, there's the generally accepted meaning of the term - that pilots just don't know enough information about what is going on around them. This is a function of the inadequacy of missile-warning receivers available today. Secondly, there is the situational awareness of the decision-makers responsible for procuring combat aircraft. All too often, EW and self-protection take a back seat to weapons and sensors that represent the aircraft's offensive capabilities. The latter issue is often rectified after a bloody nose, as described earlier. The first problem is more persistent and patently more difficult to address.

"No matter how good the flares you carry, no matter how good the pilot, and no matter how good the radar warning receiver [RWR], if a MANPADS is optically cued and fired from a blind spot in the pilot's field of view, he may not have the faintest idea that a SAM is homing in on him," Kopp said. The only robust answers to this problem are appropriate missile-approach-warning systems (MAWS) designed to alert the pilot and cue either directed IR countermeasures (DIRCM) or to control the release of flares. Many older MANPADS can be defeated by flares and/or maneuver, especially by a fighter aircraft, but to respond the aircraft must know it is under attack. "Sadly MAWS are not a ubiquitous feature of modern EW suites," he said. "In part this is due to the unavailability in previous decades of low-false-alarm, affordable, and compact systems. More recently MAWS have fallen foul of budgetary pressures, like many other items of an EW suite."

"Warning receivers are definitely the weak link," said Major William Ogden, USAF, deputy program manager for LAIRCM. "None of the warning receivers currently fielded meet the need."

Because it uses passive IR target acquisition and guidance, a MANPADS missile has left the launch tube before the pilot in the target aircraft even has a chance to notice that he is under attack. And more often than not, his eyes will be elsewhere when the rocket motor ignites and the SAM begins its assent. Hence the importance of the MAWS in keeping a lookout. Most missile-warning systems use either an IR or an ultraviolet (UV) sensor. UV sensors have limitations with high levels of ozone in the atmosphere, particularly prevalent in urban environments and daylight operations, as ozone levels increase with air pollution and sunlight. With IR sensors, sensitivity is not a problem. The difficulty is dealing with a large amount of IR data. Strong background emissions have the potential to saturate detector elements and, even under the best of circumstances, will produce a large increase in detector "noise." Plus, too many things look like a missile, particularly in industrial areas. Furthermore, the problem of passively detecting, identifying, and accurately tracking a small IR/UV source against a highly variable background is not a trivial one to solve, either in terms of hardware or software.

This raises the false-alarm problem. An industry source cites two stories that make the countermeasures circuit. The first involves a US Air Mobility Command (AMC) transport that flew into Saudi Arabia. Near the ground, the MAWS produced a false alarm of an inbound missile and automatically activated the countermeasures system, which spewed flares out to protect the aircraft against the imaginary missile. The Saudi hosts were none too pleased about US aircraft raining flares down in proximity to oil storage and transport facilities. The US response was to turn the MAWS off during takeoff and landing, arguably the times when a large aircraft is most vulnerable to a shoulder-fired missile. The second story concerns AMC planes in level flight: Then Secretary of Defense William Perry was in the cockpit as an observer during a flight into the Balkans in support of US forces there. The MAWS triggered a warning light on the cockpit instrument panel-no automatic countermeasures were dispensed this time. One of the aircrew shut it off. Perry asked what the light meant and was told that it warned of approaching missiles. So why shut it off? Too many false alarms. Why have it on the plane if it doesn't work, Perry asked, what good does it do?

These questions are more properly answered by a Secretary of Defense than a pilot. Nevertheless, MAWS is the essential technology for any effective IRCM suite. And it seems to be an open secret that many MAWS currently deployed cannot be relied upon to defend against MANPADS.

"If systems are being fielded with excessive false-alarm rates, this would point to the testing process being either inadequate or simply not representative of the operational environment," said Monash University's Kopp. "An excessive false- alarm rate may arise from weaknesses in the optical and electro-optical components of a design, as well as from signal-processing weaknesses. IR/UV MAWS are a relatively new technology in mass deployment, and the few early IR systems, such as the F-111's AAR-34 series, were never considered particularly effective nor reliable."

The false-alarm problem plays havoc with efforts to make IR countermeasures suites more effective. Pulse-Doppler radar is effective for detecting approaching missiles, although a continuously radiating set becomes a beacon to any radar receiver in range. Elta Electronics (Ashdod, Israel) is developing a missile-warning system for aircraft that uses IR or UV sensors to trigger a pulse-Doppler radar search if a missile launch is suspected. The idea is that a plane or helicopter would run quiet until it was under attack, and only then light up to track the threat and deploy countermeasures. The problem, as you may have guessed, is that if the false-alarm rate is high enough, the radar is acting as a beacon anyway.

As with any new technology there is a learning curve to be climbed, and false-alarm-rate problems in some systems reflect the reality that IR/UV MAWS have yet to reach the maturity of other components in an aircraft's EW suite. "It is indeed true that missile warning is the key to successful countermeasures," said Georgia Tech's Schmeider. "This is so well established that we can expect steady, evolutionary increases in warning capability. It is worth noting that signal-detection theory describes the trades that can be made with missile-warning sensors or any kind of signal receiver. For a given technology state, the price that must be paid for achieving a higher probability of detection is a higher false-alarm rate. So if we want to operate at the highest levels of missile detection and declaration certainties, we must be prepared to cope with a higher rate of false declarations. Of course, better signal detection and processing methods can reduce that price, but they are unlikely to ever completely eliminate it."

Researchers say several R&D directions show promise. These include the development of multi-color IR sensors, the on-going data-collection studies that measure and analyze background-clutter statistics, and the development of improved signal processors that run more complex clutter-rejection filters faster. It is also possible to develop a tolerance for false alarms into new programs.

"I don't think we will ever be rid of the false alarms," said the USAF's Ogden. "What we are doing is working to make false alarms less of an issue. The directed countermeasure overcomes many of the shortcomings of expendables in practical application in this regard. The directed countermeasure isn't limited to a finite number of uses, doesn't light the neighborhood on fire, and doesn't have the safety issues of handling pyrotechnics. Most importantly, you can apply the directed countermeasure to false alarms repeatedly without having to worry about running out of countermeasures."

A word about safety issues. The minimum safe altitude for using flares or even their use at all, even over enemy territory, has come under some scrutiny due to political fallout. Iraq, for instance, has attempted to gain some propaganda value out of the fact US warplanes drop "flare bombs" on their crops and property. This complaint fails to move pilots. "Instead of my SPO hat, I'll put my wings on here," Ogden said. "The minimum safe altitude for dropping flares is whatever altitude I'm at when the Iraqis start shooting. At that point, Iraqi crops and property are the least of my concerns. Besides, a burning aircraft falling out of the sky is likely to do a lot more damage to crops and property than a flare."

Direct to the Source

The LAIRCM program is one of several DIRCM approaches that together represent a promising, relatively new category of self-protection systems that direct a beam of IR energy to "blind" or overload an IR seeker. As such, they must present a new category of challenges to designers of these systems.

Lamps have been around for a long time. Their broad radiation patterns have been an advantage in the past because many lamp-based jammers emitted over such a wide angle that they did not have to be pointed directly at the missile. But they are not well suited to the mid-wave IR threat, because most of their spectral output is at shorter wavelengths. However, lasers are now becoming available with adequate mid-wave radiant intensity. This intensity is not the result of high laser power so much as it is the result of narrow laser beamwidth: "Recall that source radiant intensity is the output power divided by the solid angle of the output beam," Schmeider said.

Lasers can provide very narrow beams and, therefore, high radiant intensities. Of course, the down side of narrow beams is that they require high pointing and tracking accuracy to keep their beam on the threat missile. Such pointing accuracy is now being achieved as well - in tests, anyway.

Schmeider does not see any particular integration problems posed by DIRCM-type jammers as a major hurdle to their development and deployment. The lasers (preferable to lamps) are being packaged in small sizes that fit in gimbaled turret transmitters so that the need for relay optics can be minimized. Turret-housing-window and optical-integration problems are not much different from those for other IR target-acquisition and fire-control systems that have been successfully flown for decades on high- performance platforms. Most of them have also had to incorporate lasers for target-ranging and -designation functions. They have all had to contend with abrasion, as well as shock and vibration stresses. Likewise, signature management has become a required feature for most optical fire-control systems.

"If not done properly, an optical aperture can increase the platform's radar cross-section by allowing RF energy to scatter off the external surface and from inside the optical cavity," Schmeider said. "However, these effects can be managed. Missile-warning optics can be flush mounted with the skin. Windows can be treated with thin metal coatings, covered with wire grids, or use semiconducting optical materials that both transmit IR and reflect RF energy. Transmitters might be made retractable or provided with segmented or contoured domes that minimize radar cross-section."

On the other hand, others do see definite integration problems. "A key issue with MAWS and DIRCM will be packaging," Kopp said. "Many in-service aircraft may have little remaining free space in geometrically advantageous parts of the airframe, forcing the warning and IRCM equipment to be packaged into the frequently more hostile environment of fuselage or wing pylons. Pylons are also prone to movement relative to the airframe with aerolastic loads on the aircraft wings, therefore producing a more challenging environment for the tracking loops and beam stabilization."

Laser-based DIRCM may prove to be particularly challenging in this regard since a very narrow beam must be accurately directed at a threat which may be in a post-rocket burnout phase of flight and, thus, have a relatively low heat signature, against a strong emission background. The carriage environment for DIRCM can also be challenging in terms of vibration levels and temperature variations, neither of which are conducive to maintaining the precise alignment of complex optical hardware.

According to a source at the BAE Systems Jam Lab, the most significant hurdle involves operation of the integrated countermeasures suite: detecting and declaring the threat, slewing and pointing the jam head, hand-off between the warner(s) and the jam head, and countering the threat. How well an existing DIRCM system addresses MANPADS threats will depend critically upon the optical system and filter designs employed in the threat seeker, as well as the band coverage of the laser or lamp employed in the DIRCM system design. A DIRCM system will be effective only if adequate power can be delivered into the threat seeker's detector array. That's the bottom line: "Even if everything else works properly, if you don't put appropriate energy on the threat, you will get hit."

Rock, Scissors, Paper

Assigning a likelihood to future paths in threat evolution is difficult. The technology paths open to a MANPADS designer intent upon defeating a DIRCM-equipped opponent are many, the key constraint being the available technology base for the seeker.

"Kinematic defeat of DIRCM is unlikely since the weight constraints of a MANPADS are reflected in a limited propellant load, and propellant is vital if a missile is to maneuver effectively in the endgame," Kopp said. "Given that a DIRCM system tracking rate is likely to dramatically exceed the achievable angular rate changes resulting from MANPADS maneuver, I would not expect this to be a popular path for missile designers to follow."

Kopp believes that home-on IR jam has better prospects, with the caveat that a separate laser detector may be required for this purpose, designed to handle the power levels impinging on the missile seeker. An elegant strategy would be to employ optical interferometry to measure the angular difference between the impinging laser beam and the missile's velocity vector. This would allow the missile to fly itself up the beam, like a 'back to front' beamrider. While the coherency of a laser emitter is great for maintaining beam focus, it could open up opportunities for missile designers.

It is the unrealistic expectation of a perfect countermeasure that is the real challenge. There are no technologies that will enable combat aircraft to overfly enemy territory with impunity, dispensing justice like starships. Modern battlefield weapons are best employed in combined-arms operations, according to the integrated-battlespace doctrine, the way they were designed. The best defense against a MANPADS-equipped enemy, perhaps, is the soldier on the ground with a rifle who goes in to drive him off.

 

 
Copyright 2001 eDefenseonline.com & Horizon House Publications