Monday, January 28, 2008

Defending airliners against terrorist attack

A sign of the times, fitting airliners with equipment to defend against a missile attack. Three 767s owned by American Airlines will be fitted with the system developed by BAE Systems. The system detects the heat from an incoming missile and uses a laser to jam or confuse the missile's guidance. How tech! But there are said to be thousands of unaccounted for MANPADs (man portable anti-aircraft missile systems) and several incidents were commercial aircraft have been targeted by these weapons so the need is there.

The test on the 3 airliners will not entail testing the laser beams however but is to test the effect the attached system has on the aircraft's aerodynamics and everyday operations. Israeli airline El Al has already installed an anti-missile system on some airliners, said to be in a response to the possession of SA-7 missiles by Hamas. Of course in 2002 an El Al airliner was targeted by missiles in Kenya. British Airways have also considered it.

So what exactly are these defence systems? The articles do not specify what system is to be tested though BAE Systems and Northrop Grumman have developed a military system called AAQ-24 Nemesis which includes laser turrets so i assume the American Airlines airliners are being fitted either with this system or a derived one.

Of course countermeasures to held defend again incoming missiles have been around for as long as there have been anti-aircraft missiles. In the past aircraft dispensed flares (for infrared seeking threats) and chaff (for radar guided threats) but modern IR guided missiles are not so easily fooled by flares anymore. Nemesis is a Directional Infrared Countermeasures (DIRCM) which basically means the countermeasure is directed against the threat not sprayed everywhere. Ultraviolent sensors detect and track the incoming missile and then the laser jammer is targeted at the missile to hopefully confuse it enough to send it off course.

References :

BAE Systems gets funding for anti-missile testing - Flight International (07/01/08)
El Al Airlines installs anti-missile systems on passenger aircraft - Haaretz (15/02/06)
AN/AAQ-24(V) NEMESIS - Northrop Grumman brochure

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