AAQ-24

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Intended to defeat infrared guided missile threats, the AN/AAQ-24 is a directional infrared countermeasures (DIRCM) system [1] intended to defend aircraft, helicopters and other platforms from heat-seeking missiles. Named the Nemesis by its manufacturer, Northrop Grumman, it is an interim device, pending the deployment of a more general laser-based system, and is the first example of a new multinational approach to acquisition contracting.

Basic operation

After being cued onto the threat by a warning receiver such as the AN/AAR-54, it fires an intense light source, initially a xenon arc and eventually a laser, at the threatening missile, intending to overload or destroy the missile's guidance seeker.

In electronic warfare terms, this is a attack on the missile's guidance system. That the attack is being done to protect the aircraft being attacked does not, in current terminology, make it electronic protection. Electronic protection would, in this example, keep the enemy from confusing the warning receiver.

Complementary technologies

As mentioned, the device needs to be warned of the existence of the missile threat. Classic warning receivers looked for infrared energy, but the AN/AAR-24 looks in the ultraviolet spectrum, where it may be harder to hide the signal. There is no conceptual reason that a countermeasures device of this type could also get missile warning from other onboard or offboard sensors. Offboard sensors would need a communications channel to the vehicle carrying the DIRCM equipment.

Depending on the engagement geometry, DIRCM can engage during the midcourse or terminal attack phases of the missile. During these phases, other countermeasures may deceive the infrared seeker, such as flares (e.g., fired by the AN-/ALE47), radical aircraft maneuvering including moving behind obstacles, and perhaps smoke generators; the latter are especially common on ground vehicles.

Acquisition

Procurement began in 1993 for a United States Special Operations Command requirement, to protect aircraft such as the MC-130 COMBAT TALON, it also has been adopted by the United Kingdom — the actual customer of the manufacturer This procurement is a first example of an unusual cooperative acquisition strategy, where the UK actually manages the contract with the vendor, Northrop Grumman,while the US depends, operationally, on the device. [2]

Users

Representative types using AN/AAQ-24
Fixed wing aircraft Rotary wing aircraft
BaE-146 EH-101
G-550 Sea King
C-130 Hercules (some variants) MH-53 PAVE LOW
Challenger V-22 Osprey
Boeing 747 Puma
Boeing 737
Airbus 330
C-17 Globemaster III

References