Directed Infra-red Countermeasures (DIRCM): how to save a large aircraft from IR missiles

Journal of Electronic Defense ^ | November, 2001 | K.B. Sherman

Note: Regarding the recent escape by an Israeli charter airline, this is a likely technology to be applied. DIRCM uses a directed laser in a turret (see photo below) to "spoof" the incoming missile's warhead into thinking that the target is really somewhere else. DIRCM is superior to flares for several reasons, including the facts that flares are limited in number; they can cause ground fires; and they burn at one or two specific temperatures.

In October, 2001, Northrop Grumman Electronic Systems (Rolling Meadows, IL) won a $66 million contract from the US Air Force to develop a Large Aircraft Infrared Countermeasures ( LAIRCM ) System for transports. This laser-based system for defeating IR-seeking missiles is to be based on Northrop Grumman's NEMESIS Direct Infrared Countermeasures (DIRCM) System.

NEMESIS has undergone several recent upgrades. The MIMS Two-Color Infrared Missile Warning Sensor has been added, which improves dealing with threats detected against a highly cluttered background. The two-color IR concept permits spectral discrimination between target and clutter IR signatures. A prototype MIMS sensor has undergone three generations of upgrades and has participated in live fire tests involving a variety of threat missiles at Pendine, Wales; Meppen, Germany; and WSMR.Northrop Grumman and Fibertek Inc. have collaborated to develop a modular, compact, air-cooled, all-band laser for IRCM applications, known as the Viper, a modular upgrade to the existing NEMESIS system.

Viper fits in a truncated, pancake-like chassis of 13-inch diameter and 2-inch height. The entire laser chassis mounts directly to NEMESIS transmitters. The current, flight-qualified prototype version of this laser weighs less than 10 pounds, uses 320 Watts of electrical power, and delivers jamming energy in Bands I, II, and IV at significant levels above that of a lamp-based system. As another part of the NEMESIS product improvement program, a new transmitter called WANDA is being developed. WANDA is a miniature, all-laser based transmitter which takes advantage of the lack of large arc lamps to provide higher performance in a smaller, lightweight, low drag package. WANDA has a four-axis gimbaled system, which can effectively jam at nadir allowing for mounting in any position on the aircraft.

Defending against the IR-seeker weapon requires covering a number of bases, including recognition of a potential threat, identifying it, determining its range and lethal zone, how it's guided, and more. And as countermeasures evolve, we can optimistically look forward to more choices of defense than that related by one military retiree, who suggested from his own experience that, "Your best defense is to pop back into the hole you came out of!"

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