Homeland Security: Protecting Airliners From

Homeland Security: Protecting Airliners from

Terrorist Missiles

Introduction

Shoulder-fired surface-to-air missiles (SAMs), also known as MANPADS

(man-portable air defense systems), developed in the late 1950s to provide military

ground forces protection from enemy aircraft, are receiving a great deal of attention

as potential terrorist weapons. These missiles, affordable and widely available

through a variety of sources, have been used successfully over the past three decades

both in military conflicts1 as well as by terrorist organizations. The missiles are

about 5 to 6 feet in length, weigh about 35 to 40 pounds, and, depending on the

model, can be purchased on the black market anywhere from a few hundred dollars

for older models to upwards of almost a quarter million dollars for newer, more

capable models. Seventeen countries, including the United States, produce manportable

air defense systems.2 Shoulder-fired SAMs generally have a target detection

range of about 6 miles and an engagement range of about 4 miles so aircraft flying

at 20,000 feet (3.8 miles) or higher are relatively safe.3 Most experts consider aircraft

departures and landings as the times when it is most vulnerable to shoulder-fired

SAM engagement. There are a number of different types of shoulder-fired SAMs,

primarily classified by their seekers.4

Types of Shoulder-Fired SAMs

Infrared (IR)

Infrared shoulder-fired missiles are designed to home in on a heat source on an

aircraft, typically the engine exhaust plume, and detonate a warhead in or near the

CRS-2

5 Schaffer, Op Cit. p. 2.

6 Ibid., p. 3.

7 "Raytheon Electronic Systems FIM-92 Stinger Low-Altitude Surface-to-Air Missile

System Family," Jane's Defence, October 13, 2000, p. 3.

heat source to disable the aircraft. These missiles use passive guidance, meaning that

they do not emit signals to detect a heat source, which makes them difficult to detect

by targeted aircraft employing countermeasure systems. The first missiles deployed

in the 1960s were IR missiles. First generation shoulder-fired SAMs such as the U.S.

Redeye, early versions of the Soviet SA-7, and the Chinese HN-5 are considered

"tail chase weapons" as their seekers can only acquire and engage a high performance

aircraft after it has passed the missile's firing position. In this flight profile, the

aircraft's engines are fully exposed to the missile's seeker and provide a sufficient

thermal signature for engagement. First generation IR missiles are also highly

susceptible to interfering thermal signatures from background sources, including the

sun, which many experts feel makes them somewhat unreliable.

Second generation IR missiles such as early versions of the U.S. Stinger, the

Soviet SA-14, and the Chinese FN-6 use improved coolants to cool the seeker head

which enables the seeker to filter out most interfering background IR sources as well

as permitting head-on and side engagement profiles. These missiles also employ

technologies to counter decoy flares that might be deployed by targeted aircraft and

also have backup target detection modes such as the ultra violet (UV) mode found

on the Stinger missile.5

Third generation IR shoulder-fired SAMs such as the French Mistral, the

Russian SA-18, and the U.S. Stinger B use single or multiple detectors to produce

a quasi-image of the target and also have the ability to recognize and reject flares

dispensed from aircraft - a common countermeasure used to decoy IR missiles.6

Fourth generation missiles such as the U.S. Stinger Block 2, and missiles believed

to be under development in Russia, Japan, France, and Israel could incorporate focal

plane array guidance systems and other advanced sensor systems which will permit

engagement at greater ranges.7

Command Line-of-Sight

Command line-of- sight (CLOS) missiles do not home in on a particular aspect

(heat source or radio or radar transmissions) of the targeted aircraft. Instead, the

missile operator or gunner visually acquires the target using a magnified optical sight

and then uses radio controls to "fly" the missile into the aircraft. One of the benefits

of such a missile is that it is not as susceptible to standard aircraft mounted

countermeasure systems which are designed primarily to defeat IR missiles. The

major drawback of CLOS missiles is that they require highly trained and skilled

operators. Numerous reports from the Soviet-Afghan War in the 1980s cite Afghan

mujahedin as being disappointed with the British-supplied Blowpipe CLOS missile

because it was too difficult to learn to