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AN/AAR-47 Missile Approach Warning System

Employed on helicopters and transport aircraft, the AN/AAR-47 Missile Approach Warning System (MAWS) warns of threat missile approach by detecting radiation associated with the rocket motor and automatically initiates flare ejection. The AN/AAR-47 is a passive Electro-Optic Missile Warning System designed to provide warning of Surface to Air Missiles (SAMS) and pass information to countermeasures systems. Employed on helicopters and transport aircraft, the AAR-47 Missile Approach Warning System (MAWS) warns of threat missile approach, enabling the effective employment of evasive maneuvers and electronic and infrared countermeasures. Detection algorithms are used to discriminate against non-approaching radiation sources. The AN/AAR-47 system is similar to the AN/AAR-44, but instead of a revolving sensor unit it uses four IR sensors located in four quadrants on the Aircraft. The AAR-47 is a passive, missile- approach warning system consisting of four sensor assemblies housed in two or more sensor domes, a central processing unit, and a control indicator. The Warning System provides attacking missile declaration and sector direction finding and will be interfaced directly to the ALE-39/47 countermeasures dispenser. Without the AAR-47, helicopters and fixed-wing aircraft have no infrared missile detection system.

The system is used by various Navy aircraft as well as on the C-17. Full-rate production continues by Hercules, Clearwater, FL. The Microprocessor Upgrade Program is currently in the testing phase, and production began in FY 1998. Limited follow-on production will begin in the third quarter of FY 1999 through FY 2003.

The US Navy is currently upgrading the sensor portion of the AN/AAR-47 Missile Warning Set (MWS). This upgrade includes the addition of a laser warning function to the system. To serve as risk reduction for this activity, the Electronic Warfare Advance Technology (EWAT) Program of the Naval Air Systems Command, PMA-272, developed an integrated laser warning/missile warning sensor, the Advanced Tactical Aircraft Sensor (ATAS).

The ATAS system is a technology demonstrator, which integrates laser warning into a functioning AN/AAR-47. Laser warning detectors and electronics are housed in a collar around the missile warning optical aperture on the AAR-47 Optical Sensor Converter (OSC) and internal to the sensor body. Laser warning processing is done using a laser warning coprocessor developed for the Raven laser warning system. This uses an EWAT developed coprocessor board installed in a spare slot in an AN/ALE-47 Programmer to provide all laser warning processing required by ATAS.

The ATAS system was subjected to 100 hours of laboratory testing at SPAWAR Systems Center San Diego in November and December 1997 to characterize the laser warning performance of the sensor and to determine whether the system met the requirements of the development specification. Additional laboratory testing at the Naval Research Laboratory in December 1997 evaluated the performance of the missile warning function of the ATAS sensor. Forty hours of ground-based testing were carried out in December 1997 by the Precision Guided Weapons Countermeasures Joint Test & Evaluation Directorate (OTD) at AMRAD Site, White Sands Missile Range, (WSMR) New Mexico. ATAS was tripod mounted and tested with a wide range of lasers. Airborne testing of ATAS onboard an UH-1 helicopter was completed in March 1998 at WSMR, again conducted by OTD. Seven sorties (15.8 flight hours) were flown, including a dedicated false alarm test flight.

Successful completion of the ATAS program resulted in the technology being transferred to the Naval Air Systems Command Program Executive Officer (T), PMA-272, for incorporation in the sensor upgrade program of the AN/AAR-47 Missile Warning Set. The sensor upgrade program will make a number of improvements in the missile warning portion of this widely deployed system as well as adding a laser warning function with performance at least as good as the current AN/AVR-2A.






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