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Sunday, July 1, 2012

Eyes On Shooters

The Ground Fire Acquisition System gives U.S Army Apaches all-round sensors to detect and target small arms, rockets and mortars for a networked combat team

by Frank Colucci

The U.S. Army will deploy a battalion of AH-64D Apaches to Afghanistan this year with a Ground Fire Acquisition System (GFAS) that promises attack helicopter crews better situational awareness to help protect soldiers on the ground. GFAS, developed by Radiance Technologies in Huntsville, Ala., and integrated by Boeing in Mesa, Ariz., will locate gun, rocket and mortar signatures precisely and with low false alarm rates. Integrated with the Modernized Target Acquisition/Designation Sight (M-TADS) and cockpit displays already on the Block II Apache Longbow, it will put eyes on targets quickly to hit sources of groundfire and cue other members of the combined arms team. If successful, the evaluation system will also reduce risk for the new Block III Apache Longbow with cognitive decision aids meant to guide pilots around threats.

The Apache product manager (PM) considers GFAS a target acquisition system, not aircraft survivability equipment. The Extended Block II AH-64D now in the field already has a survivability suite integrated through an aircraft gateway processor. The BAE AN/AAR-57 Common Missile Warning System (CMWS), Symetrics ALE-47 Improved Countermeasures Dispenser and BAE ALQ-212 Advanced Threat Infrared Countermeasures set with multi-band laser defeat infrared-guided man-portable air defense systems (MANPADS). The Northrop Grumman APR-39B(V)2 and Goodrich AVR-2B warning receivers detect radar and laser-guided threats. Continuing helicopter losses like the Black Hawk reportedly shot down by a rocket-propelled grenade (RPG) in April nevertheless drive development of Hostile Fire Indicators (HFI) that warn air crews of unguided threats.

CMWS enhancements and the Joint and Allied Threat Awareness System (JATAS) in development are both meant to give helicopters HFI capability (Avionics, November, page 11). According to Apache Longbow PM Lt. Col. Jeff Johnson in the Army’s Program Executive Office of Aviation, “GFAS could be a bridge or part of development work that PM ASE is conducting now and in the future with regard to Hostile Fire Indication systems.” 

An AH-64D Apache of Company B, 1st Attack Battalion, 227th Aviation Regiment flies over Baghdad looking for enemy mortars and anti-aircraft threats. The Ground Fire Acquisition System will be evaluated in Afghanistan this year to give Apache crews greater situational awareness and added lethality to protect ground forces.
The airborne GFAS repackages infrared detector and processing technology from the ground-based WeaponWatch system and integrates the technology with Apache sensors and displays. “We’re in the process of installing this system on an Apache unit for evaluation purposes only,” Johnson said. “No fielding decision has been made for GFAS. After the in-theater evaluation is complete, the Army will determine if it wants to make the investment in this technology and complete a follow-on system to field on the Apache.”

Apache crews have acknowledged the difficulty of spotting dismounted enemies in rough terrain and muzzle flashes in daylight, and they have returned from missions unaware of battle damage in their aircraft caused by small arms fire. The Senate justification for Fiscal 2011 GFAS funding stated small arms and RPGs account for more than 90 percent of all the damage done to rotary wing aircraft in combat. The National Guard Association has already requested the Army fund GFAS production for Block II Apache Longbows of the Pennsylvania Guard.

Eyes On Target

Hostile Fire Indicators typically use acoustic detectors to localize the crack-bang of gunfire or more accurate optical detectors that spot muzzle or rocket flashes and show their Point of Origin (POO). Both technologies are prone to false alarms in cluttered, noisy environments. Radiance Technologies uses broadband mid-wave infrared detectors and hypertemporal processing to look at the characteristics of the weapons flash, both to reject false alarms and to classify firing events as small arms, RPGs, mortars, MANPADS or artillery.

The Army fielded the technology in the sniper-detecting WeaponWatch system at checkpoints in Iraq in 2004. For the Army’s OverWatch Advanced Capabilities Technology Demonstration, Radiance developed a weight-saving field-programmable gate array processor with embedded software. Some of the leave-behind systems went on to accumulate more than 30,000 operating hours in-theater. Weapons classification capability was added to WeaponWatch after the ACTD, and hostile intent logic enabled the system to tell if weapons were shooting at the sensor or simply in the sensor field of view. The time to locate the shooter is 5 ms to 50 ms.

The Ground Fire Acquisition System (GFAS) integrated on the Apache Longbow helicopter ties broadband mid-wave infrared sensors at the wingtips to existing displays and targeting sensors via the Aircraft Gateway Processor.
The Army Aviation

Applied Technology Directorate (AATD) at Fort Eustis, Va., flew the actively cooled, ground-based system on a Black Hawk in 2005. Radiance engineers consider the airborne HFI task comparatively easy above the clutter and noise that confuse ground systems. An aircraft version of WeaponWatch also offered a chance to eliminate heavy cooling provisions. Radiance flew an uncooled 40-pound system on a Bell JetRanger in 2007 and proved the flying sensors could detect threats beyond their lethal range with low false alarm rates. Another package flew on an AAI Shadow Unmanned Aircraft System (UAS). The Airborne Weapon Surveillance System has since been integrated into an artillery-spotting UAS for the Republic of Korea.

Subsequent flight tests sponsored by AATD put a GFAS precursor on a Boeing MD530F testbed helicopter. The Little Bird tests led to GFAS early user evaluation on the Apache. In the AH-64D integration, Radiance Technologies provides GFAS detectors in wingtip pods and an intermediate processor that sorts out overlapping fields of view and feeds the Aircraft Gateway Processor. Boeing is responsible for GFAS structural and systems integration.

Networked Apache

Army fleet plans now call for 690 new and rebuilt Block III Apache Longbows by 2026. The first production Block III AH-64D was delivered last October, and the Army expects the more powerful, better-integrated attack helicopter to achieve initial operational capability this June. Block III introduces an open-avionics architecture with greater flexibility and margin to expand. The modernization leaves Apache cockpit controls and displays largely unchanged, both to save money and to minimize the training burden on crews moving up to the new attack helicopter. Beginning with Production Lot 13 last year, Extended Block II Apache Longbows incorporated a Selex Galileo Aircraft Gateway Processor (AGP) to integrate federated survivability equipment with existing displays and targeting systems. (Wiring for the processor actually began in Block II Lots 11 and 12, so those aircraft could be updated with the AGP and GFAS.)

Cockpit displays in the Extended Block II aircraft show GFAS warnings on their Aircraft Survivability Equipment (ASE) pages. The evaluation system uses spare icons from the APR-39 radar-warning receiver to locate and classify groundfire threats. The Apache pilot or co-pilot/gunner selects ASE as the target acquisition source and presses a slave button to slew M-TADS to the target. Magnifying day/night visionics enable the user to verify the source of fire, aim the Apache gun and rockets and laser-designate targets for Hellfire missiles.

The Block III Apache Longbow introduces a new open-avionics architecture able to integrate GFAS and other add-ons better with weapons and databused communications. In the Block III cockpit, the ground fire POO would go directly to the target page and populate target files instantly. Block III modernization also gives the Apache Longbow wideband access to send and receive imagery and intelligence updates. Crews could use their own weapons to kill the threat or pass the POO via high-speed modem and JTRS radios to other units.

Block III data fusion software will ultimately fuse on- and off-board sensor data for cognitive decision aids designed to route the Longbow crew around threats and accelerate their tactical decisions. Some form of integrated HFI will also feed Intelligent Decision Aiding for Aircraft Survivability (IDAS) technology demonstration. The AATD program aims to develop a lightweight self-protection suite to counter small arms, RPGs and MANPADS. It will cue flight crews to threats with enhanced displays and defeat the threat with a multi-function visual/infrared jammer. Radiance Technologies received a contract for IDAS HFI, and AATD plans to fly the demonstrator pod on an Apache. Army Apache Longbow and Aircraft Survivability Equipment PMs are collaborating on IDAS to productionize the technology around Block III Lot 4 or 6.

Separate from GFAS development, Radiance Technologies also provided gunshot detection capability for the Raytheon Advanced Distributed Aperture System Joint Capability Technology Demonstration last year. Integrated on an AATD Black Hawk, the all-round situational awareness system detected shooters and put a display icon on the POO. The system also used three-dimensional audio cueing to alert pilots to the direction of gunfire, and it could point an eye-safe laser Visual Acquisition Disrupter at the threat.

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