How the Guardian Anti-missile System Works

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Introduction to How the Guardian Anti-missile System Works

In November 2003, a missile struck an airplane operated by global shipment company DHL as it lifted off from a Baghdad airport. The missile wasn’t fired from another aircraft or a fixed launch site, but from a handheld rocket launcher operated by one or two individuals. A similar attack, carried out by al-Qaida terrorists, threatened an Israeli plane departing from a Kenya airport in late 2002.

Missile Image Gallery

Photo Courtesy of the The U.S. Marines
Marine Lance Cpl. Gary R. Nichols fires a handheld rocket launcher during fire and maneuver training. See our missile image gallery.

Although no one was killed in either of these incidents, many experts believe that it is only a matter of time before a shoulder-fired missile brings down a commercial airliner, resulting in hundreds of civilian deaths. The threat of such a catastrophe prompted the Department of Homeland Security to conduct a three-year study to test the feasibility of installing missile defense systems, adapted from military applications, on all turbojet aircraft used in scheduled air service. One of the systems included in that study is Northrop Grumman’s Guardian^TM Solution for Commercial Airplanes.

Photo courtesy of Northrop Grumman
The Guardian Anti-missile system pod, placed on the underside of the airplane's nose.

In this article, you’ll learn about the Guardian^TM anti-missile system, as well as the specific type of weapon it is designed to foil. You’ll also learn how, in the absence of such systems, airplanes and airports can reduce their vulnerability to this particularly lethal type of attack.

What is Guardian?
Guardian is a technology designed by Northrop Grumman Corporation to detect and foil missile attacks launched against aircraft by terrorists located on the ground. In military lingo, such a technology would be called a countermeasure, and in fact, Northrop Grumman based the design of Guardian on its military countermeasure system, the Nemesis directional infrared countermeasures (NEMESIS DIRCM, officially known as the AN/AAQ-24 [V]). The NEMESIS system has been in production since 1997 and entered service in 2000. It currently protects about 350 aircraft of 33 types, from small, fixed-wing planes to helicopters.

Guardian would do the same for commercial airplanes, helping them to elude infrared (IR), or heat-seeking, missiles. Although IR missiles can be fired from many types of weapons, they are especially lethal when fired from a single-operator rocket launcher, also known as a Man-Portable Air Defense System (MANPADS). MANPADS can be fired from the ground and require no human intervention after the missile has been fired. They are easy to transport and just as easy to set up and take apart.

Photo courtesy of Varga Attilia
Infrared seeker of the R-3 air-to-air missile

By some estimates, more than 700,000 MANPADS have been produced worldwide by a number of nations. Unfortunately, many thousands are now unaccounted for, with most of those appearing on the black market, where terrorists can buy them relatively inexpensively. The main targets for terrorists armed with MANPADS are airliners, which are particularly vulnerable as they take off or land. To date, terrorist-launched MANPADS have been responsible for as many as 1,000 civilian deaths, making it one of the biggest threats to commercial airliners.

MANPADS Basics

To understand how the Guardian system works, it’s helpful to understand how missiles fired from Man-Portable Air Defense Systems work. If you read How Stinger Missiles Work, you’ll find great information about a specific MANPADS example. Here is a quick recap.

Missiles fired from Man-Portable Air Defense Systems are guided missiles, which consist of a warhead, engine, and guidance and control equipment. Because they are launched from the ground and intercept their targets in the air, MANPADS missiles fall into the surface-to-air category. They are much smaller than ballistic missiles, which look more like space rockets. Ballistic missiles travel great distances along an arching, parabolic path and are guided for only a portion of their trip. MANPADS missiles, on the other hand, fly much shorter distances and are guided for their entire flight.

Photo courtesy of U.S. Department of State
The parts that make up the man-portable air defense systems, or MANPADS

The guidance system is one of the most important parts of any guided missile. There are many different ways to control the flight path of a projectile, but almost all modern missiles take advantage of homing guidance. Homing missiles come equipped with a seeker - an onboard antenna sensitive to a specific energy source. That energy source could be any part of the electromagnetic spectrum, but one of the most easily detectable forms of energy is infrared, or heat. An infrared seeker is able to lock on to the enormous heat produced by an aircraft’s engine and, with deadly accuracy, guide the missile to its target.

Photo courtesy of Redstone Arsenal Historical Information
The Redeye missile was one of the first Man-Portable Air Defense Systems used in combat.

The U.S. Army’s Redeye missile, first deployed in the 1950s, is a classic example of this type of weapon. Indeed, the Redeye missile was named for the infrared sensor carried in its nose. Designed for simple, reliable operation, the Redeye missile could be carried anywhere a soldier could take a rifle, could be made ready to fire in seconds and required little training to use. It was used for almost two decades until the Army developed newer, more sophisticated man-portable systems.

One of those systems was the Stinger missile, another American-made weapon still in use today. Two important Russian MANPADS models include the Strela and the Igla. The Stinger and the Igla have similar capabilities, both being able to engage targets head-on, from behind and from the side. Both systems also incorporate highly advanced infrared, ultraviolet seekers that make them even more difficult to elude. We’ll talk more about that in the next section.

Photo courtesy of Megapixie
A 9K34 Strela-3 missile and launch tube (without grip stick)

Photo courtesy of Megapixie
A 9K38 Igla missile

Defending against MANPADS
There are three primary ways to defend against guided missile attacks. If the missile uses a radar-based seeker, which tracks reflected radio waves, it can be confused by chaff. Chaff refers to strips of metal foil or metal filings released by aircraft under attack. By reflecting incoming radio waves, chaff creates a false signal that the missile follows taking it off course.

Photo courtesy of The U.S. Navy
Two different types of chaff used

If the missile uses an infrared seeker, like most MANPADS do, it will not respond to chaff. But it will respond to a decoy heat signal. Decoy heat signals are easily created by lighted flares, which an aircraft can release when it detects an incoming missile. The burning flares present multiple heat signals that less sophisticated missiles can’t discriminate. However, Stinger and Igla missiles are able to distinguish between flares and the target. That’s because the seekers in these missiles can detect two types of energy -- infrared and ultraviolet. Although the infrared signal of a jet is much stronger, its ultraviolet signal is present and detectable. By creating a unique signature of its target based on dual energy sources (longer-wavelength infrared and shorter-wavelength ultraviolet), Stinger and Igla missiles are much more difficult to foil.

Helicopter releasing countermeasure flares.

Photo Courtesy of The U.S. Navy
A U.S. Navy helicopter discharges countermeasure flares, similar to the flares and chaff commercial airplanes discharge.

To defend against these more sophisticated missiles, a laser-based system is required. Lasers can do one of two things -- it either destroys the electronics in the missile’s guidance or jams the seeker so it can no longer “see” its target. Jamming is actually more common in today’s anti-missile defense systems because their lasers don’t have to be as powerful to be effective. Northrop Grumman’s Guardian solution is a laser jammer, and in the next section, we’ll look at exactly how it foils attacks made by Man-Portable Air Defense Systems.

Directional Infrared Countermeasure

Guardian is known as a Directional Infrared Countermeasure (DIRCM) and relies on two distinct systems to defend against missile attacks. The first system includes ultraviolet sensors that detect an incoming missile. The second includes the transmitter that directs a beam of infrared energy at the missile’s seeker. Both systems are enclosed within a single compact pod, which mounts to the underside of a jet’s fuselage.

Photo courtesy of Northrop Grumman
The pointer/tracker system tracks an incoming missile and directs an infrared beam at the missile's seeker.

Here’s how the systems work together:

When a MANPADS missile is fired, it produces all forms of energy across the electromagnetic spectrum. Sensors in Guardian’s missile-warning system detect the ultraviolet wavelengths and send a signal to the transmitter. Future versions of the Guardian solution could include sensors that detect two bands of infrared energy, making it easier to sense missiles at significantly greater ranges.
Once it receives a signal from the missile-warning system, the pointer/tracker assembly tracks the missile as it approaches.
A high-intensity gas arc lamp then fires a beam of infrared energy at the missile’s seeker.
For the seeker, it's like having an extremely bright light shined in its “eyes.” But Guardian doesn’t simply blind the missile. Its laser beam has a special waveform that actually gets into the missile seeker’s guidance loop and causes an error signal to build, making the missile’s guidance system think it's off course.
The guidance system responds by adjusting the missile’s flight path.
The missile eventually becomes so off course it no longer poses a threat.
The entire process occurs in two to five seconds and requires no action on the part of the aircraft crew. Once the aircraft reaches approximately 18,000 feet — the range of most MANPADS — the Guardian system shuts down until it is time to land.

Photo courtesy of Northrop Grumman

Feasibility
The technology used in the Guardian system has a proven track record in military applications. According to Northrop Grumman, NEMESIS has successfully completed more than 4,000 hours of flight testing, more than 200,000 jamming effectiveness tests, and more than 100 successful missile, live-fire engagements, including combat.

So the real question is not whether Guardian is effective, but whether the commercial airline industry can afford to implement the solution. According to a 2005 study conducted by RAND Corporation, it would cost an estimated $11 billion to install anti-missile systems on America’s 6,800 commercial airliners. Operating the systems after installation would cost up to $2.2 billion annually. Because of these figures and because resources available for Homeland Security are limited, RAND recommended that the United States look to other strategies that might be more cost-effective. But some experts weigh the cost of protecting airlines against the cost of a successful attack. For every aircraft downed, there would be $1 billion in direct costs, and indirect costs would be much more significant.

Image courtesy of U.S. Department of Homeland Security
Seal of the U.S. Department of Homeland Security

All of this is under consideration by the Department of Homeland Security. In January 2007, the department entered the third phase of its three-year feasibility study. In this phase, FedEx will fly 11 MD-10s with Northrop Grumman’s Guardian system for 18 months to test whether the equipment is cost-effective and reliable for commercial aircraft operations. A second team is studying another laser-based DIRCM system known as Jeteye. Jeteye, developed by BAE Systems, will be mounted on American Airlines’ Boeing 767s flown by carrier ABX Air. If one system is found to be more cost-effective and reliable, it could win the department’s approval. The addition of the Guardian system will not change the way the plan is flown. In fact, the system engages itself upon takeoff. If it is deployed to stop a missile, it will do so on its own; there is no need for the pilots to do anything. Once the plane hits 18,000 feet (out of range of most shoulder-fired missiles), the Guardian system will disengage until it is time to land the aircraft.

The Future

The use of Guardian or another laser-based anti-missile system on commercial aircraft is probably a matter of when, not if. But until planes have the technology installed, other measures will have to be taken to protect against attacks from MANPADS. One important measure is to improve airport perimeter security. Raytheon’s Vigilant Eagle program is designed to do just that. A ground-based system that uses a grid of sensors strategically planted around an airport facility, Vigilant Eagle can detect a missile fired towards any arriving or departing aircraft within the boundaries of the airport facility. One sensor will detect the missile, sending a signal to another sensor station, which transmits a microwave beam to kill the missile-guiding system.

Not all measures are this costly. Air-traffic procedures can be revised so that jets no longer approach runways in gradual descent patterns. By adopting spiral descent patterns and steep, rapid ascents, commercial aircraft can reduce the amount of time they are vulnerable to modern MANPADS. And for jets that do get hit by a missile, those designed with redundant systems and improved fire and explosion suppression systems will have a better chance of surviving.

The ideal solution to the MANPADS threat, of course, is a combination of systems and strategies. A multi-layered approach would make it more difficult for terrorists to launch a successful attack because they would have to subvert several protective measures. Even still, it is a formidable challenge -- one that clearly defines what’s at stake in the global war against terrorism.

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How the Guardian Anti-missile System Works