How the Guardian Anti-missile System Works

Soldier fires a handheld rocket launcher in training
Marine Lance Cpl. Gary R. Nichols fires a handheld rocket launcher during fire and maneuver training.
Photo Courtesy of the The U.S. Marines

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.

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 GuardianTM Solution for Commercial Airplanes.


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

In this article, you’ll learn about the GuardianTM 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.

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

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.



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

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.


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.

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

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.

A 9K34 Strela-3 missile and launch tube (without grip stick)
A 9K34 Strela-3 missile and launch tube (without grip stick)
Photo courtesy of Megapixie
A 9K38 Igla missile
A 9K38 Igla missile
Photo courtesy of Megapixie

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.

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.

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

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

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

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. Here’s how the systems work together:

  1. 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.
  2. Once it receives a signal from the missile-warning system, the pointer/tracker assembly tracks the missile as it approaches.
  3. A high-intensity gas arc lamp then fires a beam of infrared energy at the missile’s seeker.
  4. 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.
  5. The guidance system responds by adjusting the missile’s flight path.
  6. The missile eventually becomes so off course it no longer poses a threat.
  7. 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

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.

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.

For lots more information on the Guardian Anti-missile Defense System and related topics, check out the links that follow.


Lots More Information

Author's Note: How the Guardian Anti-missile System Works

Writing in the age of Google is both a boon and a burden. Type in a few keywords, and an entire world of information instantly appears. Then comes the task of sifting through the hundreds of thousands of links to find solid, reliable sources. With this article, I was able to supplement my online research with insights from a living, breathing missile man. That person was my father, a government engineer who worked in a variety of defense agencies over his career, including Night Vision Labs in Fort Belvoir, Va. When I told him about this assignment, he offered to sit down with me and talk about missiles and their electromagnetic signatures. He did just that as we sat in my local Starbucks on a chilly, rainy afternoon.

He didn't know about the Guardian anti-missile system per se, but he helped me understand the basics of missile guidance and detection, as well as the challenges and opportunities a weapons engineer faces when working in the infrared portion of the spectrum, which was his specialty. In the end, his insights made this an easier article to write and, I hope, an easier article to read. Even if that's not the case, I still reflect fondly on that afternoon in the coffee shop when what I do for a living intersected, however briefly, with what my father did in his 30-year career as an engineer.

  • Antczak, John. “Jet With Anti-Missile System Leaves LAX.” 01/16/AR2007011601328.html?nav=rss_business/industries.
  • BBC News. “BA considers anti-missile systems.” September 5, 2003.
  • Deutsche Welle. “DHL Plane Struck by Missile in Baghdad.” November 22, 2003.,,1039411,00.html.
  • Doyle, John M. “FedEx To Fly Counter Manpads-Equipped MD-10.” Aviation Week. September 17, 2006. story_generic.jsp?channel=awst&id=news/aw091806p3.xml.
  • Encyclopedia World Book. “Guided missile,” 2005 Edition.
  • The Federation of American Scientists. "MANPADS Proliferation."
  • The Journal of Net-Centric Warfare. “DHS Awards anti-missile contracts.” November 6, 2006.
  • Laurenzo, Ron. “Antimissile systems for airliners.” Aerospace America. March 2005.
  • Northrop Grumman’s GuardianTM Web Site index.html
  • Northrop Grumman’s NEMESIS Page
  • Northrop Grumman Corporation. “Today’s Technology … Saving Tomorrow’s Lives: GuardianTM Solution for Commercial Airplanes.” BR-066-BAS-0905-3.
  • Northrop Grumman Corporation. “AN/AAQ-24(V) NEMESIS.” DS-177-BAS-0106.
  • “RAND Study Says Airliner Anti-Missile Systems Too Expensive and Unreliable.” January 25, 2005.
  • Redstone Arsenal Historical Information. "Redeye."

Guardian Anti-missile System: Cheat Sheet

Stuff You Need to Know:

  • One of the greatest threats to military and commercial aircraft is a missile fired from a single-operator rocket launcher known as a Man-Portable Air Defense System (MANPADS).
  • Missiles fired from MANPADS are guided for their entire flight, making them especially lethal. Seekers in these systems operate in specific bands of the electromagnetic spectrum, either infrared or ultraviolet.
  • The Guardian anti-missile system is a technology designed by Northrop Grumman Corporation to detect and foil missile attacks launched against aircraft by terrorists located on the ground.
  • Guardian is a Directional Infrared Countermeasure. It contains one system to detect the ultraviolet energy of an incoming missile and a second system to disable the missile by firing a beam of infrared energy at the missile’s seeker.