Homeland Security: Protecting Airliners from Terrorist Missiles
Released: 2006-02-16T00:00:00

Introduction

Shoulder-fired surface-to-air missiles (SAMs), also known as MANPADS (man-portable airdefense systems), developed in the late 1950s to provide military ground forces protection fromenemy aircraft, are receiving a great deal of attention as potential terrorist weapons that might beused against commercial airliners. These missiles, affordable and widely available through a varietyof sources, have been used successfully over the past three decades both in military conflicts (1) as well as by terroristorganizations. 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 dollarsfor older models to upwards of almost a quarter million dollars for newer, more capable models.Seventeen countries, including the United States, produce man-portable air defense systems. (2) Shoulder-fired SAMsgenerally have a target detection range of about 6 miles and an engagement range of about 4 milesso aircraft flying at 20,000 feet (3.8 miles) or higher are relatively safe. (3) Most experts consider aircraftdepartures 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 theirseekers. (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 heat source to disable theaircraft. These missiles use passive guidance, meaning that they do not emit signals to detect a heatsource, 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 suchas the U.S. Redeye, early versions of the Soviet SA-7, and the Chinese HN-5 are considered "tailchase weapons" as their seekers can only acquire and engage a high performance aircraft after it haspassed the missile's firing position. In this flight profile, the aircraft's engines are fully exposed tothe missile's seeker and provide a sufficient thermal signature for engagement. First generation IRmissiles 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 tofilter out most interfering background IR sources as well as permitting head-on and side engagementprofiles. These missiles also employ technologies to counter decoy flares that might be deployedby targeted aircraft and also have backup target detection modes such as the ultra violet (UV) modefound 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 andalso have the ability to recognize and reject flares dispensed from aircraft - a commoncountermeasure used to decoy IR missiles. (6) Fourth generation missiles such as the U.S. Stinger Block 2, andmissiles believed to be under development in Russia, Japan, France, and Israel could incorporatefocal plane array guidance systems and other advanced sensor systems which will permit engagementat greater ranges. (7)

Command Line-of-Sight

Command line-of- sight (CLOS) missiles do not home in on a particular aspect (heat sourceor radio or radar transmissions) of the targeted aircraft. Instead, the missile operator or gunnervisually acquires the target using a magnified optical sight and then uses radio controls to "fly" themissile into the aircraft. One of the benefits of such a missile is that it is not as susceptible tostandard aircraft mounted countermeasure systems which are designed primarily to defeat IRmissiles. The major drawback of CLOS missiles is that they require highly trained and skilledoperators. Numerous reports from the Soviet-Afghan War in the 1980s cite Afghan mujahedin asbeing disappointed with the British-supplied Blowpipe CLOS missile because it was too difficultto learn to use and highly inaccurate, particularly when employed against fast moving jetaircraft. (8) Given theseconsiderations, many experts believe that CLOS missiles are not as ideally suited for terrorist useas are IR missiles, which sometimes are referred to as "fire and forget" missiles.

Later versions of CLOS missiles, such as the British Javelin, use a solid state televisioncamera in lieu of the optical tracker to make the gunner's task easier. The Javelin's manufacturer,Thales Air Defence Ltd., claims that their missile is virtually impervious to countermeasures. (9) Even more advanced CLOSversions, such as the British Starburst, use a laser data link in lieu of earlier radio guidance links tofly the missile to the target.

Laser Beam Riders

Laser beam riding shoulder-fired SAMs use lasers to guide the missiles to the target. Themissile literally flies along the laser beam and strikes the aircraft where the missile operator orgunner aims the laser. These beam riding missiles are resistant to current countermeasure systemson military and civilian aircraft. Missiles such as Sweden's RBS-70 and Britain's Starstreak, canengage aircraft from all angles and only require the operator to continuously track the target usinga joystick to keep the laser aim point on the target. Because there are no data links from the groundto the missile, the missile can not be effectively jammed after it is launched. Future beam ridingSAMs may require the operator to designate the target only once and not manually keep a continuouslaser aimpoint on the aircraft. Even though beam riders require relatively extensive training and skillto operate, many experts consider these missiles particularly menacing in the hands of terrorists dueto the missiles' resistance to most conventional countermeasures in use today.

Shoulder-Fired SAM Proliferation

Approximately 20 countries have manufactured MANPADS or their components, and it isestimated that a total of over 1 million of these systems have been manufactured worldwide. (10) Unclassified estimates ofthe worldwide shoulder-fired SAMs inventory are widely varied. Published estimates on the numberof missiles presently being held in international military arsenals range from 350,000 (11) to 500,000 (12) but disparities among nations in accountability, inventory control, and reporting procedures could make these figuresinaccurate. Tracking proliferation to non-state actors is considered even more difficult by manyanalysts. There are a variety of means that terrorist organizations use to obtain missiles, includingtheft, black market, international organized crime, arms dealers, and transfers from states willing tosupply missiles to terrorists. Often times, the only verification that a non-state actor has ashoulder-fired SAM is when a launcher or fragments from an expended missile are recovered afteran attack. (13) As in thecase of military arsenals, estimates of shoulder-fired SAMs in terrorist hands vary considerably.Estimates range from 5,000 (14) to 150,000 (15) of various missile types, but most experts agree that thevastmajority of them are IR guided and are likely SA-7 derivatives, versions of which are reportedlypossessed by at least 56 countries. (16)

Some examples attest to the large numbers of these missiles in circulation. As of December2002, coalition forces in Afghanistan had reportedly captured 5,592 shoulder- fired SAMs from theTaliban and Al Qaeda. (17) Some of these included U.S. Stinger and British Blowpipemissiles believed to have been left over from the Afghan-Soviet War. Shoulder-fired missilescontinue to be seized routinely during coalition raids, suggesting that Taliban and Al Qaeda forcesoperating in and around Afghanistan still have access to an undetermined number of these systems. In Iraq, recent press reports indicate that 4,000 to 5,000 shoulder-fired SAMs may be available toIraqi insurgent forces. (18) Africa, the region where most terrorist attacks with these missiles have occurred, reportedly also hasa large quantity of shoulder-fired SAMs left over from Cold War sponsorships and the numerouscivil wars of that era. (19)

Non-State Groups With Shoulder-Fired SAMs

Unclassified estimates suggest that between 25 and 30 non-state groups possessshoulder-fired SAMs. Table 1 depicts non-state groups believed to possess shoulder-fired SAMsthrough the 1996-2001 time period. Additional groups may have obtained missiles since 2001 butdetails at the unclassified level are not known. Actual or estimated quantities of these weaponsattributed to non-state groups at the unclassified level are also unknown.

Table 1. Non-State Groups with Shoulder-Fired SAMs:1996-2001 (20)

Note: (c) is possession confirmed through intelligence sources or actual events; (r) is reported butnot confirmed.

Recent U.S. Military Encounters with Shoulder-Fired Missiles

Recent U.S. military encounters with shoulder-fired missiles in Iraq and Afghanistan canprovide some useful operational insights which could be benefit government, industry, and civilaviation officials involved in the protection of civil aviation. In December 2003 an unidentifiedshoulder-fired SAM struck an engine of a U.S. Air Force C-17 Globemaster III cargo aircraft thathad just departed Baghdad International Airport. (21) The aircraft, which was outfitted with missile defenses, made anemergency landing at Baghdad International Airport. (22) In January 2004, a C-5 Galaxy transport aircraft - also havingan antimissile system -was hit by a shoulder-fired SAM and the aircraft was able to andsuccessfully. (23) One senior Air Force official reportedly stated that "for whatever reason, the [defensive] systems on theairplanes didn't counter [the attacks]. We don't have any indications that it was a systemmalfunction." (24) Theofficial speculated that sensor placement, and aircraft altitude and maneuvering played a role in thesesystems not functioning as they were intended. (25)

According to one report, from October 25, 2003 to January 2004, nine military helicopterswere shot down or crashed landed in Iraq after having been hit by hostile ground fire, resulting inthe deaths of 39 service members. (26) An Army study, commissioned after these incidents, reportedlyrevealed a number of findings. The study team reportedly concluded that RPGs, (27) and SA-7, SA-14, andSA-16 shoulder-fired SAMs were used in the attacks against the helicopters. (28) Another study findingrevealed that the Iraqis had studied the helicopter flight patterns and had developed effectivetechniques to engage the aircraft. (29)

According to the Chief of the U.S. Transportation Command (USTRANSCOM), U.S.military cargo aircraft take ground fire in Afghanistan and Iraq from shoulder-fired SAMs,anti-aircraft artillery and small arms on almost a daily basis. (30) USCENTCOM officialswere unable to provide an unclassified update on shoulder-fired missiles attacks against U.S. militaryaircraft in Afghanistan and Iraq as of September 2004, although classified data of this nature isbeing tracked by USCENTCOM and DOD. (31) Some analysts believe that the U.S. has significantly improvedaircraft countermeasures and defenses and modified aircraft operating procedures, resulting in fewersuccessful attacks, but others suggest that attacks with shoulder-fired SAMs have become socommonplace that they no longer garner the attention that they once did.

Civilian Aviation Encounters with Shoulder-Fired Missiles

Estimates vary, but the most widely reported statistics on civilian aircraft experience withshoulder-fired missiles indicate that, over the past 26 years, 35 aircraft have come under attack fromthese weapons. (32) Ofthose 35, 24 were shot down resulting in more than 500 deaths. (33) While these statistics havebeen frequently cited, at least one report has suggested that these figures may significantly overstatethe actual numbers of civilian-use aircraft that have been attacked by shoulder-fired missiles. (34) That report insteadconcluded that only about a dozen civil-registered airplanes have been shot down during this timeperiod and further notes that some of these aircraft were operating as military transports when theywere shot down. On the contrary, available statistics may underestimate the total number of civilianencounters with shoulder-fired missiles. It is possible that some aircraft shootings may have beenattributed to other causes for various reasons and are not included in these statistics. Also, it ispossible that some failed attempts to shoot down civilian airliners have either gone undetected orunreported.

For many incidents considered to be a shoulder-fired missile attack against a civilian aircraft,there is scant information to make a conclusive determination if that was, in fact, the case. In someinstances, while it is widely recognized that the incident was a shooting, there is no conclusivedetermination regarding the weapon used. For example, in some instances of aircraft shootings thereare discrepancies among accounts of the event, with some reporting that the aircraft was broughtdown by a shoulder-fired missile while others claim that anti-aircraft artillery was used. Also, inmany instances there are questions as to whether the flight operation was strictly for a civilian useor may have been for military or dual use (civilian/military) purposes. Therefore, there is nouniversal agreement as to which incidents should be included in the tally of civilian aviationencounters with shoulder-fired missiles.

Based on our review of available reports and databases on the subject, the statistic of 24catastrophic losses out of 36 aircraft appears to be a reasonable estimate, but not a definitive count,of the total worldwide civil aviation shootings with shoulder-fired missiles or similar weapons. However, since most of these incidents took place in conflict zones, they are not typically consideredto be politically motivated because the targeted aircraft may have been perceived as being used formilitary purposes. (35) While most of these historical examples do not provide any particular insight into the politicalmotivation behind shootings of civilian aircraft in the current context of the global war on terrorism,they do provide some indication of the possible outcomes of such an attack. Based on the commonlycited statistic of 24 aircraft destroyed out of 36 attacks over the past 26 years, the odds of survivingan attack are not particularly encouraging. Using these numbers, the odds of surviving an attack maybe estimated to be only about 33%. However, it is important to note that these incidents include awide variety of aircraft types including small piston-engine propeller airplanes, turboprop airplanes,helicopters, and business jets, as well as large jet airliners. Since the current legislative proposalsand administration efforts to date have been aimed at addressing ways to protect large commercialjet airliners from shoulder-fired missiles, it is useful to examine past incidents involving these typesof aircraft in order to gain further insight regarding the threat.

CRS reviewed various sources and found only six incidents where large turbojet airlinerswere reported to have been attacked by shoulder-fired missiles. These incidents are listed in Table2 . (36) Whether all ofthese incidents were in fact attacks using shoulder-fired missiles is still a matter of considerabledebate as conclusive evidence supporting such a finding is lacking for most of these incidents. Ofthese six encounters identified, there was a wide range of outcomes. Only two of the six shootingsresulted in catastrophic losses of the airplanes -- killing all on board. In three other incidents, theairplanes received significant damage -- but no one was killed. Finally, in the widely reportedNovember 2002 attempt to shoot down an Israeli charter jet in Mombasa, Kenya, the aircraft wasfired upon by two missiles but was not hit.

Table 2. Suspected Shoulder-Fired Missile Attacks AgainstLarge Civilian Turbojet Aircraft (1978-Present)

In the first instance, the official findings by Angolan authorities attributed theNovember 8, 1983, crash of a TAAG Angolan Airlines Boeing 737 to a technical problemwith the airplane, but UNITA rebels in the area claimed to have shot down the aircraft witha surface to air missile. (37) All 130 people on board were killed, potentially makingthis the deadliest single incident involving a shoulder-fired missile attack against a civilianaircraft. However, investigation of the incident failed to produce any conclusive evidenceof missile or gunfire damage on any of the aircraft wreckage.

In the February 9, 1984, attack of a TAAG Angolan Airlines Boeing 737, the airplanewas struck at an altitude of 8,000 feet during climb out. The crew reportedly attempted anemergency landing at Huambo, Angola, but were unable to extend the flaps because ofdamage to the airplane's hydraulic systems. Consequently, the crew was unable to slow theairplane sufficiently before landing and overran the runway by almost 600 feet. The airplanewas a total loss but no one was killed. (38) Investigators found evidence leading them to suspect thata bomb detonation in the forward hold, rather than a missile, was responsible for the damageobserved. However, press accounts reporting that the aircraft was struck by an SA-7 firedby UNITA guerillas have led some to conclude that this incident was, in fact, a shoulder-firedmissile attack. (39)

In the September 21, 1984, incident, an Ariana Afghan Airlines DC-10 was struckcausing damage to two of the airplane's three hydraulic systems. While some sources (40) defined thisincident as a shoulder-fired missile attack, another account indicated that the DC-10 was hitby "explosive bullets." (41)

The most recent catastrophic loss of a civilian aircraft from a suspected MANPADSattack was the October 10, 1998, downing of a Congo Airlines Boeing 727 near Kindu,Democratic Republic of Congo. The aircraft was reportedly shot down by a missile, possiblyan SA-7, that struck one of the airplane's engines. Tutsi rebels admitted to the shooting,claiming that they believed the airplane to be carrying military supplies. The final call fromthe Captain indicated that the aircraft had been hit by a missile and had an engine fire. It wasreported that a missile struck the airplane's rear engine. The ensuing crash killed all 41persons on board. (42)

The most recent attempted shooting of a passenger jet was the November 28, 2002,incident involving an Israeli-registered Boeing 757 aircraft operated by Arkia Israeli Airlines. Two SA-7 missiles were fired at the airplane on departure from Mombasa, Kenya but missed. While the threat of shoulder-fired missiles has long been recognized by aviation securityexperts, this incident focused the attention of many in Congress and the Bush Administrationon this threat and options to mitigate it. Unlike the prior attacks on jet airliners that occurredin war torn areas, the Mombasa attack was clearly a politically motivated attack, believedto have been carried out by terrorists with links to Al Qaeda. (43) That fact, coupledwith already heightened concerns over aviation security in the aftermath of the September11, 2001, terrorist attacks, has made the shoulder-fired missile threat a key issue forhomeland security.

Amid this heightened concern over the threat of shoulder-fired missiles to commercialaircraft, a DHL cargo airplane was struck by a missile on November 22, 2004, whiledeparting Baghdad International Airport in Iraq. The aircraft's left wing was struck outboardfrom the engine. Damage from the missile severed the airplane's hydraulic lines. However,the flight crew was able to return to the airport applying differential thrust on the two enginesto maneuver and operating manual cranks to lower the landing gear. The aircraft, an AirbusA300-B4, departed the runway on landing causing additional damage, including extensiveengine damage from ingesting sand and debris. (44) While no one was killed or injured, the airplane wasdetermined to be a total loss.

Options for Mitigating Missile Threats

Most observers believe that no single solution exists to effectively mitigate the SAMthreat to airliners. Instead, a menu of options may be considered, including improvementsor modifications to commercial aircraft, changes to pilot training and air traffic controlprocedures, and improvements to airport and local security.

IR Countermeasures and Aircraft Improvements

Military aircraft employ a variety of countermeasures to mitigate the threat posed bySAMs. With few exceptions, commercial airlines today do not employ these protectivesystems. (45) Historical arguments against fielding countermeasures on airliners include their acquisitioncost, cost and difficulty of integrating them into the aircraft, life cycle costs, environmentalconstraints on their use, and the fear that they may promote perceptions that flying is not safe.Estimates of the cost of acquiring and installing IR countermeasures on commercial aircraftrange between $1 million and $3 million per aircraft. (46) According to FAAforecasts, there will be about 6,839 passenger jet aircraft in service in 2006, including 3,692large narrow body airplanes, 599 large wide bodies, and 2,098 regional jets. Additionally,there are expected to be 1,011 all-cargo jets deployed in air carrier operations in 2006. (47) Estimates onequipping the air carrier jet fleet with IR countermeasures vary because of assumptionsregarding the type of system, whether they would be installed directly into the aircraft orattached via a pod, and the overall number to be procured. Some IR countermeasures couldincrease the airline's operating costs by increasing the aircraft's weight and drag and thus theamount of fuel consumed. Another issue for installing IR countermeasures on passenger jetsis the logistics of equipping the fleet and the potential indirect costs associated with takingairplanes out of service to accomplish these installations. An analysis by the RANDCorporation found that, in addition to an initial purchase and installation cost of about $11billion, it would cost about $2.1 billion annually in terms of both direct and indirect orincidental costs to maintain and sustain aircraft-based IR countermeasures on a fleet of 6,800passenger jets. (48)

For decades, military aircraft have ejected inexpensive flares to foil IR-guided SAMs.When a white-hot flare passes through an IR-guided SAM's field of view, its intense IRenergy can confuse the missile and cause it to lose its lock on the targeted aircraft. Althougheffective against older shoulder-fired SAMs, flares often cannot fool newer models, whichuse more sophisticated sensors. Also, most flares pose a fire hazard to combustibles on theground, and may be too risky for urban areas. DOD has recently developed new flares andsimilar decoys that may be more effective against modern IR-guided missiles, and pose lessof a fire hazard.

Military aircraft also use a variety of transmitters known as IR countermeasures orIRCMs to create fields of IR energy designed to confuse shoulder-fired SAMs. Unlike flares,IRCMs do not pose a fire hazard to combustibles on the ground. Like flares, however, theyare only effective against older IR-guided missiles. Recent advances in lasers have led to thedevelopment and employment of directed IRCMs (DIRCMs), that focus their IR energydirectly on the incoming SAM. DIRCMs are able to generate more jamming power thanIRCMs, and may offer the most effective defense against modern shoulder-fired SAMs.DIRCM weight, size, cost, and reliability, however, may not yet make them attractive forcommercial airlines.

Military aircraft use flares and IRCMs preemptively: in anticipation of a SAM launch,a pilot can eject numerous flares, or turn on the IRCM to foil a potential threat. However,environmental considerations may make the use of flares difficult for commercial airlines. DIRCM's can't be used preemptively. They must be aware that a missile has been launched,and use missile approach and warning systems (MAWS) for that function. (49) Because IR-guidedSAMs are difficult to detect, MAWS performance is a key factor in the overall effectivenessof the aircraft's protection system. DIRCM reliability and maintainability has also frequentlybeen cited as a key factor that will determine the cost effectiveness of these systems forcommercial use. Some estimate that current DIRCM system reliability will have to improveby a factor of 10 before they will be cost effective in a commercial setting. (50)

"Camouflaging" commercial aircraft, (i.e. reducing their optical and IR reflectivityand emissivity) would make it more difficult for terrorists to employ most shoulder-firedmissiles. Suppressing or otherwise mitigating the engine's hot exhaust may be the mosteffective way to "camouflage" commercial aircraft. DOD and industry studies indicate thatthe IR signature of large aircraft engines can be reduced by as much as 80% by shielding orducting the engine exhaust, or mixing ambient air with hot jet exhaust. (51) These measuresmay adversely affect engine performance or aerodynamic drag. Also, integrating thesemeasures into existing aircraft may cause problems with aircraft weight and balance.Regardless, DOD has conducted numerous studies on IR-signature reduction, and theexploration of this body of work may merit investigation for commercial applications. (52)

DOD is also developing paint that is designed to reduce an aircraft's IR reflectivityand visual profile. IR camouflage paint would not reduce an engine's heat signature, but itmight make it more difficult for terrorists to visually see the aircraft, and thus could avert aSAM launch. The Navy is studying IR camouflage paint on the V-22 Osprey . (53) The cost andmaintainability of this paint is still being studied, but the paint might actually be lighter thanconventional aircraft paint. Today, IR paint appears to offer few complications for airlineapplication compared to other potential countermeasures.

Infrared signature reduction techniques appear worth examining. However, it shouldbe recognized that these measures cannot make aircraft completely invisible in the IRspectrum. An airplane's IR signature will always be much stronger than that of thesurrounding sky. Thus, like many other options discussed in this report, IR signaturereduction techniques may be able to reduce an aircraft's vulnerability to IR-guided weaponsand mitigate the IR missile threat to some degree, but they cannot completely eliminate thethreat. Regardless, some in Congress recognize that IR-signature reduction may be one toolto help mitigate IR-guided missiles. In their FY2006 report ( H.Rept. 109-359 ) appropriationsconferees added $1.3 million to the Navy's $42.6 million request for electronic warfaredevelopment. The purpose of this added funding was to pursue "infrared signature reductionto mitigate terrorist missile threats."(p.393).

In addition to equipping airliners with missile countermeasures, strengthening theairframe to better withstand missile strikes has been suggested. To date, the FAA'sCommercial Aircraft Hardening Program has primarily focused on studying how hardenedaircraft can better withstand internal bomb blasts. (54) The survivability of passenger jets following missilestrikes is largely unknown, although DOD's Joint Live Fire program and the Air Force haveinitiated a multi-year effort to test the vulnerability of large turbofan engines, such as thosethat power commercial aircraft, to shoulder-fired missiles. (55) It is expected thatdeveloping hardened aircraft structures will be a challenging problem given that IR guidancesystems seek hot engine exhaust and will likely detonate at or near an aircraft engine.

Since most jet airliners have wing-mounted engines, hardening of surrounding aircraftstructure will likely be infeasible, particularly with regard to modifying existing aircraft. However, some aircraft survivability experts believe that isolating critical systems, likeredundant hydraulic lines and flight control linkages, and improving fire suppression andcontainment capabilities could prevent catastrophic failures cascading from the initial missilestrike. (56) Whilesuch options can be integrated into new aircraft type designs, they are unlikely to have anynear term impact on reducing the threat since retrofitting existing air carrier jets with damagetolerant structures and systems is likely to either be technically infeasible or not economicallypractical. Moreover, aircraft hardening options will likely require extensive research andtesting before their feasibility and effectiveness can be adequately assessed. Initialindications suggest that aircraft hardening and structural redesign, if feasible, will likely bevery costly and could take many years to implement.

Improved Pilot Training and Air Traffic Procedures

Airline pilots already receive substantial simulator training on handling loss of powerto one engine during critical phases of flight such as takeoffs and landings. This trainingshould already prepare flight crews to handle a loss of engine power resulting from a missilestrike. Therefore, additional training for handling missile attacks may be of limited benefit. On the other hand, specific simulator exercises using missile attack scenarios may bebeneficial by preparing pilots to fly and land a damaged aircraft. Modern airliners are builtwith redundancy in avionics and flight control systems, and consequently, a missile strikethat does not cause a catastrophic structural failure would likely be survivable if the flightcrew is properly trained to handle such a scenario.

Another potential mitigation technique is training flight crews in evasive maneuversif fired upon by a shoulder-fired SAM. However, this approach would not likely be effectiveand presents significant risks. Without a missile detection and warning system, it is unlikelythat a flight crew would have any indication of a missile launch. Also, large transportcategory airplanes are generally not maneuverable enough to evade a shoulder-fired SAM. There is also concern that defensive maneuvering of large transport category airplanes couldresult in a loss of control or structural failure. (57) Consequently, most observers concur that evasivemaneuvering is not a viable option for mitigating the risk of missile attacks. However,properly trained crews may be able to use other special procedures to evade missile attacks. Examples of procedures that may be considered to reduce the airplane's heat signature andvulnerability to missile strikes include minimizing the use of auxiliary power units and otherheat sources when operationally feasible; minimizing engine power settings; and, if a missilelaunch is detected, reducing engine power settings to minimum levels required to sustainflight at a safe altitude. The effectiveness and safety risks associated with techniques suchas these will need to be carefully assessed before procedural measures are implemented.

Another mitigation technique may be to alter air traffic procedures to minimize theamount of time airliners are vulnerable to missile launches and make flight patterns lesspredictable. Current arrival procedures rely on gradual descents along well defined andpublicly known approach courses that place airplanes within range of shoulder-fired SAMsas far away as 50 miles from the airport. (58) Similarly, departing aircraft with heavy fuel loadsoperating at high engine power, often along predefined departure routes, may be particularlyvulnerable and can be targeted up to 30 miles away from the airport before they climb abovethe effective range of shoulder-fired SAMs. (59)

Military aircraft often use spiral descents from altitude above the airfield whenoperating in hostile areas. Using spiral descents may be an option for mitigating the threatof terrorist SAM attacks to airliners approaching domestic airports. Doing so can limitapproach and descent patterns to a smaller perimeter around the airfield where securitypatrols can more effectively deter terrorist attacks. While spiral approaches may beimplemented on a limited basis, wide scale use of spiral patterns would likely requireextensive restructuring of airspace and air traffic procedures. This technique may presentsafety concerns by greatly increasing air traffic controller workload and requiring pilots tomake potentially difficult turning maneuvers at low altitude. The use of spiral patterns couldalso reduce passenger comfort and confidence in flight safety. Also, this technique wouldnot mitigate the risk to departing aircraft, which are generally considered to be the mostvulnerable to missile attacks.

Another technique used by military aircraft, particularly fighter jets, to reducevulnerability on departure is to make steep, rapid climb outs above the effective range ofsurface to air missiles over a short distance. Like spiral descents, such a technique haslimited application for civilian jet airliners. A typical climb gradient for these aircraft isbetween 400 and 500 feet per mile, which means that they remain in range of shoulder-firedmissiles for about 40 to 50 miles after departure. Even if the airplane were to double itsclimb rate, which would probably be close to the maximum practically achievable climb ratefor most jet airliners, the distance traveled before safely climbing above the range ofshoulder-fired missiles would still be 20 miles or more. Climbing out at such a steep ratewould also pose a risk to the aircraft since it may not provide an adequate margin of safetyif an engine were to fail during climb out. Also, steep climb angles are likely to be perceivedas objectionable by passengers.

Another option that may be considered is to vary approach and departure patterns. Regularly varying approach and departure patterns, in non-predicable ways, may make itmore difficult for terrorists to set up a shoulder-fired SAM under a known flight corridor;and, may increase the probability that they will be detected, while trying to locate a usablelaunch site, by ground surveillance, local law enforcement, or civilians reporting suspiciousactivities. One challenge to implementing this technique is that aviation radio frequenciesare not protected, and terrorists might gather intelligence regarding changing flight patterns. Also, flight tracking data are available in near real time from Internet sources and may beexploited by terrorists to gain information about aircraft position. Nonetheless, this approachcould be a deterrent by making overflights of particular locations less predictable. Limitations to this approach include disruption of normal air traffic flow which may resultin delays, increased air traffic controller workload, and possible interference with noisemitigation procedures. Varying air traffic patterns may be a viable mitigation technique,particularly at airports with low to moderate traffic and for approach and departure patternsthat overfly sparsely populated areas. Also, maximizing the use of over water approach anddeparture procedures, when available, coupled with measures to limit or restrict access to andincrease patrols of waters under these flight paths has also been suggested as a mitigationalternative. (60)

Other suggested changes to air traffic procedures include the increased use ofnighttime flights and minimal use of aircraft lighting. However, this approach is likely to beopposed by the airlines and passengers since there is little demand for night flights in manydomestic markets. Furthermore, minimizing the use of aircraft lighting raises safety concernsfor aircraft collision avoidance. While the airspace system includes good radar coverage inthe vicinity of airports and airliners are required to have collision avoidance systems, the lastline of protection against midair collisions is the flight crew's ability to see and avoid otheraircraft. Therefore, increased use of night flights and minimizing aircraft lighting is notthought to be a particularly viable mitigation option.

Improvements to Airport and Local Security

One of the most expedient measures that can be taken to mitigate the risk fromshoulder-fired SAMs to airliners is to heighten security, surveillance, and patrols in thevicinity of airports served by air carriers. The difficulty with implementing these securitymeasures is that the approach and departure corridors where aircraft operate within range ofshoulder-fired SAMS extend for several miles beyond airport perimeters. Therefore, whileheightening security in the immediate vicinity of an airport may reduce the threat fromshoulder-fired SAMs, these measures cannot effectively mitigate the threat during the entireportion of flight while airliners are vulnerable to attack. Nonetheless, using threat andvulnerability assessments, airport and airspace managers can work with security forces todetermine those locations beyond the airport perimeter that have high threat potential andwhere aircraft are most vulnerable to attack. Using this information, security can concentratepatrols and surveillance in these high risk areas. Airport security managers will likely needto work closely with local law enforcement to coordinate efforts for patrolling these high riskareas.

Terrorist acts are preceded by planning activities, much of which is observable.Because law enforcement officers can't be everywhere, public education and neighborhoodwatch programs in high risk areas may also be effective means to mitigate the threat. The AirForce has instituted a "neighborhood watch"-type program that might serve a model forbroader application. Civilians and servicemembers are trained in the "Eagle Eye Program"to recognize elements of potential terrorist activity, and how to most effectively report theirobservations. (61)

Aerial patrols using sensor technology, such as Forward Looking Infrared (FLIR),may also be an effective tool for detecting terrorists lurking underneath flight paths. However, use of aerial patrols may significantly impact normal flight schedules andoperations, particularly at the nation's larger airports.

Detecting and eliminating a terrorist threat before an attack is initiated is the optimalsolution. If terrorists are not detected prior to launch, rapid detection and accurateidentification of a missile attack would be a critical step in an effective defense. In 2004DOD evaluated ground-based warning systems composed of networked arrays of differentkinds of sensors (e.g., electro-optical, radar). Such ground-based sensor grids couldpotentially warn and cue aircraft-based, or ground-based missile countermeasures.

Ground-based missile countermeasures could potentially take many forms. Randomly dispensing flares in the vicinity of airports has been suggested, noting that theIsraeli airline El Al occasionally used this technique during periods of heightened tension inthe 1980s. However, ground-based flares pose a risk of fires on the ground and thereforewould not be suitable at many airports in the United States, particularly those surrounded bypopulated or wooded areas. Furthermore, dispensing flares may be annoying to some andmay also diminish public confidence in the safety and security of air travel. Ground basedinterceptors are another option that has been suggested. These interceptors could be vehicle-mounted SAMs like the Marine Corps "HUMRAAM" system, or directed energyweapons like the Army's tactical high-energy laser (THEL). The THEL has successfullyintercepted rockets and artillery shells in tests. (62) Cost, reliability, probability of intercept, and potentialside-effects and unintended consequences would have to be weighed when considering theseoptions. Older "lamp-based" IR countermeasures might also offer some missile jammingcapability, by generating wide, if relatively weak, fields of IR energy near airports. Industryis also exploring, and promoting, the potential deployment of microwave-basedcountermeasures. Ground-based antennas could emit a microwave pulse intended to defeata terrorist missile by "jamming" or confusing its electronic systems. Again, costs, potentialside-effects, and unintended consequences of all of these potential approaches would haveto be assessed. The risk of interfering with, or actually shooting down a commercial aircraft,for example, may be of primary concern.

Another way to mitigate the threat of shoulder-fired SAMs is through intelligence andlaw enforcement efforts to prevent terrorists from acquiring these weapons, particularlyterrorists operating inside the United States. Congress may consider ways to improve currentmissile non-proliferation efforts, and may also wish to debate ways to better shareintelligence information with airport security managers so that appropriate security measurescan be implemented to respond to specific threat information.

Nonproliferation and Counterproliferation Efforts

Legal transfer of shoulder-fired SAMs is not governed by an international treaty. The Wassenaar Arrangement (63) is the only international agreement that addressesshoulder-fired missiles sales and provisions governing these sales were not adopted by its 33members until December 2000. In December 2003, the Wassenaar Arrangement adoptedstrengthened guidelines over control of shoulder-fired SAM transfers. (64) Recent actions bythe Administration may, however, renew emphasis on nonproliferation. According to pressreports and a White House Fact Sheet (65) President Bush obtained commitments from 21 Asian andPacific Rim members of the Asia Pacific Economic Group (APEC) to "adopt strict domesticexport controls on MANPADs; secure stockpiles; regulate MANPADs production, transfer,and brokering; ban transfers to non-state end users; and exchange information in support ofthese efforts." APEC leaders meeting in Bangkok also agreed to strengthen their nationalcontrols on MANPADs and review progress at next year's APEC meeting in Chile. (66)

Since September 11, 2001, the G-8 countries (67) have givenincreased emphasis to multilateral efforts to reduce the proliferation of and risk fromMANPADS in terrorist hands. At the 2003 G-8 summit, member countries agreed to promoteadoption of Wassenaar's strengthened MANPADS export guidelines by non-Wassenaarcountries. The G-8 also implement the following steps to prevent terrorist acquisition ofMANPADS:

"To provide assistance and technical expertise for the collection, securestockpile management and destruction of Manpads surplus to national security requirements;

To adopt strict national export controls on Manpads and their essentialcomponents;

To ensure strong national regulation of production, transfer andbrokering;

To ban transfers of Manpads to non-state end-users; Manpads shouldonly be exported to foreign governments or to agents authorised by a government;

To exchange information on uncooperative countries and entities;

To examine the feasibility of development for new Manpads of specifictechnical performance or launch control features that preclude their unauthorized use;

To encourage action in the International Civil Aviation Organization(ICAO) Aviation Security (AVSEC) Working Group on Manpads." (68)

At their 2004 Summit, G-8 countries agreed upon an action plan to implement and expandthe scope of the 2003 recommendations. (69)

The International Civil Aviation Organization (ICAO), a United Nations SpecializedAgency, has also increased efforts to limit the proliferation of MANPADS. ICAO hasproposed that all 188 member countries adopt the Wassenaar Arrangement MANPADSexport guidelines, and develop a "universal regime of control for MANPADS." (70)

The U.S. State Department has undertaken a number of bilateral and multilateralefforts to reduce the number of shoulder-fired SAMs that could conceivably fall into thehands of terrorists. (71) Through the Small Arms and Light Weapons DestructionProgram (72) theState Department is working with countries or regions where there is a combination of excessshoulder-fired SAMs, poor control, and a risk of proliferation to terrorist groups or otherundesirable groups to destroy excess stocks and develop security and accountabilitymeasures.

Promising agreements have been reported. On February 24, 2005, for example, theUnited States and Russia announced an agreement to facilitate efforts to destroy obsoleteMANPADS and cooperate in reducing the potential for future proliferation. (73) The United Stateshas also worked with its NATO partners to reduce MANPADS stockpiles. On February 18,2005, the NATO Partnership for Peace Trust Fund Project was established to help theUkraine destroy its stockpiles of excess munitions, including MANPADS. Other countries,such as Serbia, Bosnia-Herzegovina, Cambodia, Nicaragua, and Liberia have pledged todestroy excess MANPADS in their possession.

These formal and informal agreements have led to a reduction in MANPADS. As ofSeptember 20, 2005, the State Department reported a total of 17,000 excess or illicitly heldMANPADS have been destroyed world-wide. When countries have balked at implementingtheir pledges, economic and diplomatic pressure have been brought to bear. The BushAdministration, for example, threatened to withhold military aid to Nicaragua until thatcountry destroyed approximately 1,000 SA-7s (74)

There are a number of both formal and informal counterproliferation actions thatcould be undertaken. Informally, U.S. and coalition forces routinely seize and destroy cachesof shoulder-fired SAMs during combat operations in Afghanistan and Iraq, thereby reducingthe number of these systems available for terrorist use. Formally, the U.S. is offering $500for each shoulder-fired SAM turned over to authorities in both Iraq and Afghanistan. (75) According to onepress report, 317 shoulder-fired missiles had been turned over to U.S. military authorities inIraq since May 1 2004, with the U.S. paying out over $100,000 in rewards for themissiles. (76) Other formal options could include infiltrating black market, organized crime or terroristgroups, and seizing or destroying these missiles or setting up "sting" operations to arrest armsbrokers and seize their missiles.

Shoulder-Fired Missile Design and Manufacture

It may be possible to incorporate specific characteristics in the design andmanufacture of new shoulder-fired missiles that would make it more difficult for terroriststo use them. While these measures would have no effect on the shoulder-fired missiles thathave already been manufactured and proliferated, they could be part of a long-term strategyfor reducing the threat to commercial aviation.

Permissive Action Links (PALs) is one example of a technology that could beincorporated in future shoulder-fired missiles to "tamper-proof" them. PALs are essentiallymicrochip-based cryptographical "trigger locks" that ensure that only authorized personnelcan use a given weapon system. Congress has shown interest in exploring PALs for Stingermissiles ( H.R. 3576 , p.219), but a lack of implementation suggests resistanceon the part of the Army. It may be that Army representatives fear that PALs could complicatelegitimate use of a shoulder-fired missile. Incorporating PALs could potentially raise the costof a weapon system. Thus, incorporating them on a multi-lateral basis may be required soU.S. manufactures are not put at an export disadvantage vis-a-vis foreign manufacturers.

Congressional Action on Shoulder-Fired Missiles

Many in Congress have expressed concern about the threat MANPADS could poseto civil aircraft. Specific concerns include protecting civilians and mitigating the potentialfinancial burden for an already besieged airline industry. Legislation has been proposed, andcongressional committees have received classified briefings on the subject in closed doorhearings. (77) During the 108th Congress, Representative Steve Israel and Senator Barbara Boxerintroduced legislation ( H.R. 580 , S. 311 ) directing the Secretaryof Transportation to issue regulations requiring airliners to be equipped with missile defensesystems. (78)

Language in the conference report accompanying the Emergency WartimeSupplemental Appropriations Act of 2003 ( P.L. 108-11 ; H.Rept. 108-76 ) directed theDepartment of Homeland Security (DHS) Under Secretary for Science and Technology toprepare a program plan for developing such missile protection systems for commercialaircraft. This program was subsequently funded in appropriations legislation and isprogressing. The program is described in detail below in the section of this report addressingAdministrative Plans and Programs.

The National Intelligence Reform Act of 2004 ( P.L. 108-458 ) directs the Presidentto urgently pursue international treaties to limit the availability, transfer, and proliferation ofMan-portable Air Defense Systems (MANPADSs), such as shoulder-fired missiles, worldwide. The act further directs the President to continue to pursue internationalarrangements for the destruction of excess, obsolete, and illicit MANPADS stockpilesworldwide. The act requires the President to report on diplomatic efforts to addressMANPADS non-proliferation and requires the Secretary of State to provide the Congresswith annual briefings on the status of these efforts. The act also requires the FAA toestablish a process for expedited certification of airworthiness and safety for missile defensesystems that can be mounted on commercial aircraft. The act also requires the DHS toprovide a report within one year assessing the vulnerability of aircraft to MANPADS attacksand plans for securing airports and aircraft from this threat.

At least three other bills introduced during the 108th Congress addressed methods formitigating the threat of shoulder-fired missiles to commercial aviation. H.R. 4056 , H.R. 5121 Section 23, and H.R. 10 Section 4103 all calledfor the pursuit of further diplomatic and cooperative efforts (including bilateral andmultilateral treaties) to limit availability, transfer, and proliferation of MANPADS.Additionally, they call for a continuation of current efforts to assure the destruction of excess,obsolete, and illicit stocks of MANPADS worldwide. These bills also called for theestablishment of agreements with foreign countries requiring MANPADS export licenses andprohibiting re-export or retransfer of MANPADS and associated components to a third party,organization, or foreign government without written consent of the government that approvedthe original transfer.

Section 2241 of the State Department Authorization Bill ( S. 2144 ) mirrored the provisions of the three bills described above. Section 2125 of the bill provided$10 million in the "Nonproliferation, Antiterrorism, Demining, and Related Programs"account for multilateral and bilateral efforts to reduce the threat of MANPADS. ( P.L.108-447 .)

In FY2006, several committees considered legislation pertaining tocounter-MANPADS programs. DoD requested $13.3 million in research and developmentfunds for a "MANPADS Defense Program" (P.E. # 0604618D8Z). This is to investigate thedevelopment of a ground-based, electro-optical sensor grid that is hoped to provide launchdetection and warning of shoulder-fired missiles. Key aspects of this program are to leveragecommercially available technologies to lower cost, and to ensure that system is suitable foruse in urban environments. Defense authorization conferees ( H.Rept. 109-360 , p. 600)matched the administration's funding request. Appropriations conferees ( H. Rept. 109-359 ,p.444) provided $5.5 more than requested.

Administration Plans and Programs

In response to P.L. 108-11 / H.Rept.108-76 , DHS submitted a plan to Congress on May22, 2003. (79) Theplan specifies a two year time frame for development, design, testing, and evaluation of ananti-missile device on a single aircraft type. The plan anticipates that a parallel FAAcertification effort will coincide with this system development and demonstration leading toan FAA-certified system that can be operationally deployed on commercial aircraft at the endof the two year project or soon thereafter.

The program plan submitted by DHS estimated that the costs to carry out this projectwould consist of $2 million in FY2003 for administrative costs, $60 million in FY2004 forsystem development and initial testing, and an unspecified amount, not to exceed $60million, in FY2005 to complete development and demonstration of the system and obtainFAA certification. The Department of Homeland Security Appropriations Act for 2004 ( P.L.108-90 ) fully funded the requested $60 million in FY2004 for this effort and an additional$61 million was appropriated in FY2005 ( H.R. 4567 /P.L 108-334). ForFY2006, the requested amount of $110 million was fully appropriated for carrying theprogram into the next phase of more detailed system refinement, testing, and certification fordeployment on a wide variety of commercial passenger jets. This effort is expected toconclude in FY2007.

The DHS established the system development program in a manner that would applyexisting technologies from the military environment to the commercial airline environmentrather than developing new technologies. In this manner, the DHS hopes to leverage militaryinvestment in counter-MANPADS technology in order to identify a technical solution thatcan be deployed in the civil aviation environment in a much faster time frame assuming thatsuch a system can be tailored to meet the operational needs and requirements of civilianflight operations.

The DHS established a Counter-MANPADs Special Program Office (SPO) tomanage the program which the DHS envisions will consist of three phases. Phase I, whichwas completed in July 2004, consisted of an intensive six-month effort to assess proposedsolutions based on threat mitigation capabilities, system costs, airframe and avionicsintegration, and FAA certification issues. Three contractor teams led by Northrop-Grumman,BAE Systems, and United Airlines were awarded $2 million each to develop detailed systemsdescriptions and analysis of economic, manufacturing, maintenance, systems safety, andoperational effectiveness issues for applying their systems in the commercial aircraftenvironment.

Following a DHS-led review of each contractor team's Phase I work and theirproposals for Phase II, on August 25, 2004, DHS awarded $45 million to BAE Systems andNorthrop Grumman to carry out Phase II of development. (80) Phase II consistedof an 18-month prototype development and evaluation based on existing technology. Bothcontractors received awards of about $45 million each for this effort which is currentlywrapping up with the delivery of two complete countermeasure units per contractor. Bothcontractors developed systems that rely on laser-based directed IR countermeasures (i.e.,DIRCM) to protect commercial aircraft from IR-guided MANPADS attacks. The UnitedAirlines-led team which was not selected for Phase II, had instead proposed a system thatwould have used expendable flare decoys to divert incoming missiles. (81) According to DHSofficials, two primary reasons why the United team was not selected was that there weresafety issues on the flight line for the expendable pyrotechnic decoys and that there wereissues with the system concerning false alarms. (82)

The BAE Systems team, which also includes American Airlines and Honeywell, andthe Northrop Grumman team, which includes Federal Express and Northwest Airlines, havedeveloped prototypes over an 18 month period that are being tested on commercial aircraft.The Northrop Grumann prototype system, called Guardian, and the BAE Systems prototype,dubbed JetEye, both underwent airborne testing on widebody airliners to determine theireffectiveness. Final flight testing and completion of Phase II, originally targeted for January2006, has been delayed until late February or early March 2006, although representativesfrom both companies stated that initial data indicate both systems have been able to meet testrequirements specified by DHS. (83) Both firms, BAE Systems and Northrop Grumman, havealso developed directed energy infrared countermeasures systems for the U.S. military. (84) Northrop Grummanis currently delivering its Large Aircraft IRCM system for installation on U.S. Air Force C-17and C-130 transports while BAE is developing and delivering an IRCM system for U.S.Army aircraft. (85)

That next phase of the DHS counter-MANPADS program for commercial aircraftwas funded in FY2006 appropriations and the intent of this additional funding is to gainfurther experience installing and testing the systems on a broader array of commercial aircrafttypes and improve the robustness of the systems under operational conditions encounteredin the commercial aviation environment. The FY2006 DHS Appropriations Act ( P.L.109-90 ) provides $110 million to award contracts for Phase III of the civilian airlinecounter-MANPADS program. This phase will include delivery and installation ofpre-production equipment on commercially operated aircraft by U.S. cargo carriers similarto those aircraft dedicated to meet the Civil Reserve Air Fleet (CRAF) requirement. To fostercompetition, the funds are planned to be used to maintain two contractors in Phase III. (86) During the PhaseIII effort, both companies will install test systems on a variety of aircraft types and obtaincertification for use on additional aircraft types. The goals of Phase III include live-firetesting, improving system reliability to meet performance specifications for commercialairline applications, adding ground notification alerting capabilities, and developing securityfeatures to safeguard sensitive military technology in units installed on aircraft that travelinternationally or are exported to foreign countries. (87)

A House proposal to designate $10 million of the FY2006 appropriation for the DHScounter-MANPADS program toward emerging alternative counter-MANPADS technologywas not included in the final FY2006 appropriation. That proposal, contained in Housereport language, expressed concern that counter-MANPADS technologies currently beingpursued under the DHS program "will not be sufficiently able to meet the challenges ofcommercial application at a cost that is economically feasible" and recommended that somefunds be directed toward assessing other emerging technologies, principally ground-basedcountermeasures, that "may be simpler and more cost effective, but are far from fullydeveloped." (88) While annual operating and support (O&S) costs -- estimated by the RAND Corporation tobe a little over $300,000 per airplane (89) -- has raised significant concerns among both commercialairplane manufacturers and airlines over the use of aircraft-based counter-MANPADSsystems, policymakers have not directed the DHS to formally examine alternativetechnologies, although the House did recommend doing so. However, as previously noted,FY2006 DoD appropriations included R&D funding for ground-based electro-optical sensorarrays to detect and warn of shoulder-fired missile attacks.

The FY2007 President's budget request includes $4.88 million for theCounter-MANPADS SPO to continue oversight and evaluation of the Phase III contractsexpected to be awarded in FY2006 and carried out in the FY2006-FY2007 time frame. TheFY2007 President's budget does not seek any additional funding for new DHSCounter-MANPADS initiatives beyond or in addition to the Phase III contracts.

Conclusion

No single solution can immediately and completely mitigate the shoulder-fired SAMthreat. As Congress considers possible legislative and oversight approaches, it is likely thatit may consider implementing various combinations of available mitigation alternatives inwhole or in part. In addition, Congress may consider phasing in mitigation options to bestrespond to available threat assessments or other criteria. For example, if threat assessmentsindicate that large widebody airplanes are most at risk, Congress may consider whetherinitially equipping these airplanes would more effectively deter the threat of missile attacks. Congress may also consider whether it would be more effective to initially equip aircraft usedon overseas flights, particularly those operating in countries or regions where the risk ofmissile attacks is greatest. Congress may also debate whether equipping only a portion ofthe air carrier fleet would be a sufficient deterrent, whether all-cargo jets should be equipped,whether passenger carrying regional jets should be equipped, or whether equipping the entireair carrier fleet is needed to adequately mitigate the threat.

Equipping aircraft with missile countermeasure systems has advantages.Countermeasures are fixed to the aircraft, require little or no flight crew intervention, and canprotect the aircraft even when operating in areas where ground-based security measures areunavailable or infeasible to implement. Down sides include a high cost, and potentiallyundermining passenger confidence in the safety and security of air travel. Also, becauseimplementation will take time, countermeasures cannot immediately mitigate today's terroristthreat. Procedural improvements such as flight crew training, changes to air trafficmanagement, and improved security near airports may be less costly than countermeasuresand could more immediately help deter domestic terrorist attacks. However, these techniquesby themselves cannot completely mitigate the risk of domestic attacks and would not protectU.S. airliners flying to and from foreign airports.

Congress and the Administration have initiated preliminary actions intended toprovide a degree of protection to commercial airliners. Legislation introduced in the 108thCongress ( H.R. 580 / S. 311 ) called for the installation of missiledefense systems in all turbojet aircraft used in scheduled air carrier service. The Departmentof Homeland Security (DHS) appropriations for 2004 ( P.L.108-90 ) designated $60 millionfor development and testing of a prototype missile countermeasure system for commercialaircraft and DHS initially envisioned a two year program totaling about $100 million todevelop, test, and certify a suitable system. Congress provided an additional $61 million tocontinue the program in FY2005 ( P.L.108-280 ), and for FY2006, designated $110 millionto conduct a more extensive third phase of the project that is anticipated to be carried outover the next two years. These actions may constitute a starting point for the considerationof additional protective measures designed to address all aspects of the shoulder-fired SAMthreat.