The Threat from Portable Anti-Aircraft Missiles

The AirSafe Journal
vol. 1 num. 17 - 2 December 2002
Todd Curtis, PhD

While the threat of attacks on airliners using portable surface to air missiles has been a possibility for decades, the 28 November 2002 attack on an Israeli airliner in Mombasa, Kenya has made this threat much more real. This attack, which fortunately did not result in any injuries or aircraft damage, did not support the idea that the threat is much higher than before. If anything, it supports the idea that a successful attack using this kind of technology is not as easy as it may first appear.

The Technology of Portable Anti-Aircraft Missiles
This kind of weapon, sometimes referred to as a man-portable, shoulder-fired, low-altitude surface to air missile, is designed to allow a single person to shoot down low flying aircraft. Made by many countries, the basic design includes the following elements: a launcher, propulsion system, guidance system, and an explosive warhead. These missiles use a passive infrared homing system in order to guide itself to a heat source, usually an aircraft engine's exhaust. While the capabilities of these weapons vary, the altitude and speed of airliners near airports are will within the range of these weapons.

Once launched, this kind of missile needs no further guidance from the operator. While some military aircraft are equipped with systems that foil a missile's guidance system, most airliners, including those flown by U.S. and European carriers, have no such protection.

The Difficulty of Launching a Successful Missile Attack
In order for an attack with a portable missile to be successful, an individual or group that intends to shoot down an aircraft would need three things: motivation, one or more missiles, and an opportunity to use these weapons. Given the events of the past year or so, it can be assumed that there are groups or even individuals that are targeting airliners for political or economic reasons. Also, there are ample opportunities to use such weapons near airports. While access to the areas within an airport's perimeter is limited, most airports in the U.S. and Europe have little restriction to areas around the airport. These areas often have roads, commercial areas, and residential areas that are freely accessible by the public. Making these areas part of the secure zone of an airport and limiting public access would not be feasible

The last element, the availability of a missile, is the most difficult for a would-be attacker. While these kinds of weapons have been produced in the tens of thousands over that last few decades, it does not follow that it would be easy to shoot down an airliner.

Like any weapon, a portable anti-aircraft missiles has to be properly operated and properly maintained if it is to be reliable, accurate, and effective. While these weapons are designed to allow a soldier to launch a missile with little formal training, such training typically does not include maintaining or testing the weapon.

As with any sophisticated technology, if any subsystem of the missile does not function correctly, or if the missile is not operated in the way that it was designed, the missile may not be able to track and hit its target. As a result, having a working missile does not guarantee that the missile will hit a target.

There is another reason why a missile attack on an airliner may not be successful. Every large airliner certified to fly in the U.S., Europe, and in most other areas of the world are designed to be able to safely fly and land after losing power on one engine. Since every large airliner has at least two engines, it makes it less likely that a successful missile strike will result in the loss of the aircraft.

While it is true that a missile may affect other parts of the aircraft, most portable anti-aircraft missiles are designed to home in on the hottest part of the aircraft, typically the engine exhaust area. Also, these missiles are typically designed to be effective against smaller military aircraft, not large jet transports. Of course, an attack with multiple missiles may be able to take out multiple engines. However, as the events in Mombasa showed, an attack with multiple missiles is no guarantee of striking an aircraft even once.

Limited Responses to the Threat
Given the nature of the threat, three of the most effective ways to reduce the threat are to implement some kind of countermeasure system on aircraft, implement a ground based countermeasure system, and increasing the secure zone around airports. However, each of these options are not likely to happen.

Putting countermeasure systems onto civilian aircraft is certainly technically feasible since it is currently done for many military aircraft, but it is not a solution that could occur quickly. It typically takes years before any major change to the design and operation of commercial aircraft could be certified, tested, and installed. Ground based solutions such as military type anti-missile systems or increased patrols around airports could certainly be done, but logistically it would be very difficult. In the U.S. alone there are over 400 airports that have commercial airline traffic, often with traffic volumes and traffic patters that change throughout the day.

While making areas near airports more secure may be very effective and may be accomplished relatively quickly, it is possible only at a high social cost. Many airports in the U.S. and elsewhere are adjacent to the communities that they serve. Severely limiting travel and other normal activities in surrounding residential and commercial areas may represent an unacceptable burden on those communities.

How Passengers Should Respond to this Threat
One clear result of events in Mombasa is that those who wish to attack airliners with portable anit-aircraft missiles and those that are trying to prevent such attacks to use portable missiles against aircraft are now much more aware that such attacks are possible. Whether this results in other attacks is not so clear. Passengers are simply unaware of key information, such as the effectiveness of governments and law enforcement organizations to stop such attacks or the availability of portable anti-aircraft missiles. At this point, any decision by a passenger to either fly or not fly can't be based on any hard evidence. Unfortunately, it is also quite likely that the traveling public will be aware of any future attacks only after a missile is launched.

Successful Missile Attack on an A300 on 22 November 2003
Congressional Research Service Report on Missile Threats