The threat from MANPADS

Aircraft continue to be symbolic targets, simultaneously representing concepts that many terrorist groups abhor - modernity, cosmopolitanism, science and affluence, as well as the country they are flagged under. While there have not been any hijackings in the past two years (perhaps terrorists realise that, since 11 September 2001, passengers may no longer be acquiescent hostages), recent incidents in Kenya and the UK indicate that terrorists may instead seek to shoot down aircraft with surface-to-air missiles such as MANPADS. The circumstances leading to the arrest of Hemant Lakhani in New Jersey on 12 August 2003 are a timely reminder that these weapons are available on the black market.

Insurgent forces fighting defensively and asymmetrically, such as those in Africa and Chechnya, have traditionally been attracted to these cheap, portable and widely available weapons.

In November 2002, two Strela-2M missiles were launched against a Boeing 757 passenger jet belonging to Israel's Arkia airline as it was departing Mombasa airport in Kenya. In February 2003, it is believed that Al-Qaeda was planning to break into Legoland near Windsor, southern England, to fire a shoulder-launched missile at an El Al airliner using the nearby airport at Heathrow.

Widespread availability

There are an estimated 50,000 to 100,000 MANPADS units on the black market, according to H Allen Holmes, a former US Assistant Secretary for Defense who was commissioned to evaluate the threat in 1998. Their availability has led to an estimated 27 terrorist groups being in possession of one or more missiles, costing as little as US$5,000 apiece on the black market. Many of these weapons can be traced back to Afghanistan. The Strela-2Ms used in Mombasa were part of a batch manufactured in the Soviet Union in 1974 that remained in Afghanistan after the Soviets withdrew. One launch tube from this cache was used unsuccessfully against an US F-15 fighter aircraft when it was taking off from a US Air Force base in Riyadh, Saudi Arabia, on 5 May 2002. Al-Qaeda is also believed to be in possession of a number of Stinger missiles originally provided to the Mujahideen in Afghanistan by the US.

MANPADS offer other attractions to terrorists. They generally have an extended shelf life and are designed to withstand battlefield conditions. Their batteries and other components can be easily replaced by commercial substitutes. At the same time, their small size allows them to be easily transported, stored, and deployed undetected.

Dangers to commercial aircraft...

Military aircraft often have defence systems (such as flares) that detect and divert an approaching missile, but commercial aircraft are not known to be equipped with such countermeasures. It seems highly unlikely that airlines, many of which are now severely cash-strapped, are willing to fit anti-missile systems that cost around US$1 million per aircraft. Besides, decoys do not fool Stinger missiles. The most obvious countermeasure, therefore, is to secure the perimeter of airports - a daunting task given that a missile could be fired from a discreet position several kilometres away by an individual carrying nothing more suspicious than a large suitcase.

A series of co-ordinated, high-profile MANPADS attacks would have significant consequences beyond the inevitably large loss of life. As there are no obvious countermeasures available, governments would be left with no option but to ground commercial aviation in high-risk areas. This would be disruptive and demoralising on a civilian population who otherwise take domestic air travel for granted, and would result in an adverse economic and political effect. Those countries that are commercially or geographically dependent on aviation as an international link - such as the UK, Australia and Singapore - are in a particularly vulnerable position.

...But all is not lost

Fortunately the characteristics of MANPADS and modern aviation may present terrorists with a few difficulties:

·Direction of attack: MANPADS can correct their path while chasing the heat source of their target, but they have limitations. In one second, a Strela-2M missile travels 580m, yet it can only correct its path by up to 6º (meaning that at its tightest a Strela-2M can barely bank a full 40º before reaching its maximum range). This suggests that terrorists would need to find a secluded position underneath the expected flight path of an aircraft.

·Heat sources: heat-seeking missiles can be distracted by heat sources other than the plume of their target, such as the sun.

·Altitude envelopes: older MANPADS do not target well in low altitudes. Strela-2Ms may not be able to lock onto a heat source properly if fired from a position lower than 30-50m above sea level (ASL), and Stingers also have a minimum operating altitude (30m for the 9M31, 10m for the 9M31M). Most of the world's major airports are in fact located at relatively low altitudes - Bangkok's Don Muang airport is two metres ASL, New York's John F Kennedy airport is four metres ASL, and Heathrow lies 25m ASL. Conversely, Mombasa is 60m ASL. Terrorists may of course fire from an elevated position that makes up the difference, but suitable structures are less likely to be found near the end of a runway.

·Range of attack: missiles also have minimum and maximum firing ranges. One theory is that the Mombasa attack failed because the missiles were fired too close to the aircraft - Strela-2Ms are inert for the first 800m they are in flight, and they usually are triggered to self-destruct if they fail to hit a target within the maximum range of 4,200m.

·Target identification: It may be difficult to orchestrate an attack on a specific aircraft. Flights are often delayed. Air traffic control authorities may change the runways in use. Indeed, at Mombasa two teams were used - one at either end of the airport's sole runway. A terrorist group targeting a specific aircraft would need several spotters around the airport to warn the team armed with the launchers situated beyond the runway. Extra operatives and radio chatter could increase the likelihood of an attack being foiled. And it is even harder to attack at night or in poor visibility, or fire at an aircraft that is landing. Tellingly, El Al flights from Mumbai, Bangkok, Nairobi, Cairo, Larnaca and other high-risk airports depart at night.

·Equipment Failure: While MANPADS are robust, their reliability cannot be guaranteed. It is believed that one of the missiles fired in Mombasa failed to self-destruct due to a technical fault.

·Collateral Damage: While MANPADS can be directed against specific targets, a aircraft shot down into an urban area could indiscriminately kill more people. Al-Qaeda may have chosen Mombasa because bodies of water exist at both ends of the runway, into which the Arkia jet could have crashed without harming the local Muslim population.

Fortunately MANPADS have their own limitations and weaknesses, which could be exploited as part of an effective strategy to mitigate their threat against commercial aviation. For example, vantage points could be secured that are in range and have a clear line of sight to the rear of departing aircraft. However, more advanced weapons are able to overcome some of these problems and terrorists may still be able to compromise security and cause chaos, even if they miss. Therefore, governments should be actively seeking out and destroying MANPADS stockpiles, particularly the more advanced missiles.

Martin Landauer is an analyst at the Terrorism Intelligence Centre in Canberra, Australia