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Sunday, May 1, 2005

Finding Ways To Stay In The Fight

Frank Colucci

The U.S. Army updates aircraft survivability equipment and reconsiders airborne weapons for full-spectrum military operations.

The U.S. Army has so far lost about 15 helicopters to a mix of high- and low-technology air defenses in Operation Iraqi Freedom. Late-model man-portable air defense systems (manpads) and simpler, unguided weapons have downed or damaged Apaches, Black Hawks, Chinooks and Kiowa Warriors.

The Army is already fielding better aircraft survivability equipment to counter the shoulder-fired missiles and wants advanced sensors able to detect and identify dismounted enemies just under a mile (1.5 km.) away. Yet despite today's emphasis on full-spectrum military operations, precision helicopter weapons to minimize collateral damage in close, complicated, urban combat were cancelled in a flurry of defense budget cuts.

Full-spectrum military operations include both high-intensity warfare against integrated air defenses and stabilization operations opposed by fleeting threats. In Iraq today, Army aviators trained and equipped to defeat networked radars, guns and missiles on linear battlefields look for homemade mortars on city rooftops. Hellfire missiles designed to kill main battle tanks are launched at dug-in urban fighters. The low altitudes and airspeeds typically used to evade sophisticated air defenses take helicopters into the lethal envelope of rocket-propelled grenades (RPGs) and cruder threats. The Army acknowledges at least one aircraft shot down in Iraq by an improvised explosive rocket or mortar.

The Army cancelled the low-observable RAH-66 Comanche last year in part to fund survivability gear improvements for its existing helicopter fleet. Painful losses in Iraq and Afghanistan showed warfighters that the dense, integrated air defenses for which the Comanche was designed are now less immediate threats than dismounted insurgents with manpads. The Defense Dept. estimates 700,000 shoulder-fired, infrared-seeking surface-to-air missiles are in circulation, at least some of them in the hands of 20 terrorist groups. In November 2003, an Iraqi missile downed an Illinois National Guard Chinook, killing 16 soldiers, wounding 20 more and triggering a political firestorm about survivability equipment priorities for deployed aircraft.

The Army has the lead among the joint U.S. services for rotary-wing survivability equipment and now fields nine different survivability-gear A-kits on helicopters in combat theaters. (A-kits are the functional countermeasures mated with B-kit wiring and racks already in the aircraft.) Until recently, Apaches, Black Hawks and Kiowa Warriors in harm's way typically carried the aging AN/ALQ-144A infrared jammer, AN/APR-39A(V)1 radar warning receiver and AN/AAR-47 missile warning receiver. Though bigger Chinooks usually had no infrared jammers, CH-47Ds were equipped with the AN/AAR-56 missile warning receiver as well as the radar warning receiver. Apaches, Black Hawks and Chinooks alike were outfitted with M130 flare/chaff dispensers.

Modern manpads have the sensitivity and discrimination to see past infrared jammers and decoy flares. At ranges greater than 0.62 mi. (1 km.), they can hit helicopters just 3-5 sec. after launch. Smarter, faster missiles are not the only threats to low-flying helicopters. At ranges less than that, RPGs and other infantry weapons remain deadly, especially in urban combat where shooters hide among innocents.

The Army Aviation Center at Fort Rucker, Ala. formed a forensic Aircraft Shoot Down Assessment Team to identify weapons used by the enemy in Iraq. Knowing the type of weapons responsible for combat losses enables deployed commanders and aircrew to use tactics techniques and procedures that mitigate the threat. Fort Rucker also teaches lessons learned in Iraq to initial-entry pilots in their go-to-war aircraft as part of the Flight School XXI curriculum. In the near term, better tactics techniques and procedures are expected to reduce helicopter losses. Shoot-on-the-run tactics free Apaches from their vulnerable firing hover. Better base security, variable aircraft routes, reduced hovering and loitering, and flying at night whenever possible all deny the enemy aiming opportunities.

Also under way are improvements to survivability equipment across the fleet of active Army, Guard and Reserve helicopters deployed to combat zones. The Army Communications and Electronics Command mounted a major effort to upgrade survivability equipment and deployed small Field Assistance Support Teams to upgrade and repair the equipment and train helicopter operators and maintainers in theater. The latest warning receivers and jammers counter evolving infrared (IR), radar (radio frequency, or RF) and laser-guided threats. Unguided air defenses will drive development of even newer countermeasures.

Infrared-seeking manpads have grown smarter and more sensitive since their debut in the 1960s. Today's Band IV IR-imaging weapons ignore seductive jammers and flares to seek the exhaust plumes around and the hot transmissions within helicopters.

The Apache and Black Hawk have infrared engine exhaust suppressors, and the OH58D can be outfitted with thermal blankets to reduce IR signature. Smarter, more sensitive missile seekers nevertheless demand active countermeasures. The U.S. Army first fielded the AN/ALQ-144 infrared jammer against Band I threats in the late 1970s. The ALQ-144A(V)5 on Apaches in Afghanistan and Iraq provides some Band IV protection against SA-12 and SA-16-vintage missiles.

Fine desert dust quickly clogged mechanical and optical parts in the air-cooled IR jammers during Operation Desert Storm. More than a decade later, the same problem in combat led to the ALQ-144C upgrade with quick-to-clean sand filter and more powerful blower motor. BAE Systems is delivering new ALQ-144Cs and providing filter kits for the Army to install in the field.

Ultimately, the Army expects the BAE Advanced Threat InfraRed CounterMeasures (ATIRCM) suite to defeat current and emerging IR threats. The full ATIRCM package ties the AN/AAR-57 Common Missile Warning System (CMWS) and AN/ALE-47 Integrated CounterMeasures Dispenser (ICMD) to the AN/ALQ-212 Directed IR CounterMeasures (DIRCM) jammer.

The new passive CMWS senses ultraviolet missile plumes and provides both the discrimination to prevent false alarms and the precision to aim the active DIRCM. Unlike the ALQ-144 broadcasting IR energy in all directions, the fast-moving ALQ-212 ATIRCM gimbal with its own IR sensor aims a cesium flash-lamp and modulated laser directly at the incoming missile to degrade the threat guidance system. The "smart" ALE-47 dispenser meanwhile launches a "cocktail" of M212, M211, and M206 flares sequenced to maximize their decoy power should the jammer fail.

The missile warning system and new countermeasures dispenser were first deployed in November 2003. The Army is now installing the CMWS and ICMD on all Apaches, Black Hawks, and Chinooks deploying to Iraq and Afghanistan. The OH-58D is not scheduled for an ASE upgrade. Scout crews will have to wait for the arrival of the new Armed Reconnaissance Helicopter in late 2008 to receive CMWS and ICMD protection.

Despite the preponderance of IR threats in Iraq and Afghanistan, Korea and other global hotspots are packed with air defense radars. RF threats, in part, kept the Apaches of Task Force Hawk out of Kosovo in 1999, and they continue to evolve. Advances in microelectronics will someday put RF seekers on manpads.

The key to defeating mixed RF threats is knowing their location and identity. U.S. Army pilots have long relied upon the APR-39A passive Radar Warning Receiver (RWR) to cue them to RF threats. However, the venerable RWR is prone to false alarms and cannot provide the precision threat bearings needed to shoot back. The Army is considering upgrades from the Navy's Northrop Grumman APR-39B(V)2 to drive a digital map and an APR-39C with modern processors to handle a broader range of threats. However, the objective system remains the ITT AN/ALQ-211 Suite of Integrated Radio Frequency Countermeasures (SIRFC).

The ALQ-211(V)1 SIRFC expected on the Block III, Lot 2 AH-64D Apache is initially a passive RWR able to identify and locate threat emitters on a digital map. It defines threat zones on cockpit displays to avoid and target enemy radars, and it can grow to incorporate active jamming functions. The jammer growth portion of SIRFC replaces the AN/ALQ-136 pulse jammer made by ITT Avionics and the ALQ-162 continuous wave jammer from Northrop Grumman. It applies the appropriate waveforms and jamming techniques automatically to defeat emitting threats. SIRFC plans nevertheless remain unclear.

Laser-based air defenses also have evolved, from handheld rangefinders in the 1970s, through beam-riding missiles in the 1980s, to laser-augmented air defense guns in the 1990s. Continuous wave, directed-energy weapons are expected around 2010. The Goodrich AVR-2A laser warning receiver was first fielded on the OH-58D Kiowa Warrior. The refined AVR-2B(V) upgrade detects rangefinder, designator, and command lasers yet reduces false alarms dramatically. It is already integrated with ATIRCM and SIRFC in the Advanced ASE suite on the Special Operations MH-60K.

Though manpads remain the principal threat to Army helicopters in Iraq, the optically-aimed weapons so lethal in Vietnam and Somalia still have no real countermeasures. The Army Aviation Advanced Technology Directorate and various Army laboratories are investigating countermeasures for RPGs, infantry assault weapons, and improvised mortars, mines, and rockets. The countermeasures could be applied to Army aircraft starting in 2007 and 2008.

Knowing the location of small arms threats improves the survivability of helicopter crews dramatically. The mostly-classified initiative includes visual-threat cuing sensors to locate threats on the ground within less than 5 degrees. The UV-sensitive CMWS may provide some indication of small arms fire, but AATD has new concluded sensors are necessary to detect and identify enemy personnel at ranges from 1 to 1.5 km. The sensors of the cancelled Unmanned Combat Armed Rotorcraft were supposed to find the most difficult targets - dismounted, camouflaged combatants hidden in ground clutter.

Army aviation has made few changes in the menu of guns, missiles, and rockets available to helicopter crews in OEF and OIF. The 30 mm M230 cannon of the Apache has grown more accurate on the AH-64D just by virtue of digital fire control computers better able to compensate for airframe deflection. No specific gun changes are planned for the Block III AH-64D.

The U.S. Army Project Manager Soldier Weapons located at Picatinny Arsenal has launched full-rate production of the 7.62 mm M240H door gun for Black Hawks and Chinooks. The highly reliable machine gun replaces the Vietnam-era M60 and has a flash suppressor to work with night-vision goggles. An egress kit quickly converts the spade-trigger helicopter weapon to a butt-stock infantry configuration. FN Manufacturing Inc. in Columbia, S.C. is producing 100 guns a month. Plans call for 3,900 M240Hs delivered to aviation units through 2007.

General Dynamics Armament and Technical Products is meanwhile qualifying the three-barreled GAU-19/A 12.7 mm Gatling gun on the OH-58D as part of the Army's Kiowa Warrior Block I Software and Weight Reduction Initiative. The electrically operated weapon fires approximately 1,000 rounds per minute in the proposed Kiowa Warrior configuration. Full qualification, including firings at Yuma Proving Grounds, is required before procurement of the GAU-19/A can be considered for OH-58D units. The powerful gun is already in service on the AH-6 Little Birds of the 160th Special Operations Aviation Regiment.

With the Lockheed Martin Joint Common Missile (JCM) canceled by Pentagon Program Budget Decisions in February, the Hellfire missile remains the precision standoff weapon of the AH-64. Lockheed Martin continues deliveries of the Semi Active Laser (SAL) Hellfire II missile to the U.S. Army through Fiscal 2008. Most of the new missiles will be AGM-114N models with a thermobaric metal augmented charge warhead developed by the Navy. Unlike the standard AGM-114K Hellfire anti-armor warhead that detonates with a sharp, short pressure spike, the thermobaric Hellfire generates a sustained pressure wave that propagates through buildings. Deliveries to the Army start in Fiscal 2006.

The Joint Common Missile was expected to give Army and Marine attack helicopter crews a choice of Hellfire-like lobbing trajectories or TOW-like direct fire to strike protected targets. Deliveries of the AGM-114L Longbow (radar) Hellfire conclude in late Fiscal 2005 or early Fiscal 2006. However, with JCM apparently out of the picture, the Army is considering more Hellfire missiles with spiral improvements such as a dual-mode seeker. Despite its precision, the Hellfire remains an "overmatch" for many soft targets including lightly armored or supply vehicles, command and control facilities, and boats. The laser-guided 70mm rocket of the Advanced Precision Kill Weapons System (APKWS) promised a precision weapon with just one-third the weight and cost of the Hellfire. A smaller precision weapon could also reduce collateral damage in close, urban combat. Like the Hellfire, the guided rocket could strike targets designated by the launch aircraft or other platforms on the air or on the ground. Program goals called for a Circular Error Probable (CEP) of less than 6.5 ft. (2 m.) versus the unguided Hydra 70 rocket with a CEP of about 100 ft. (30 m.). With its existing Target Acquisition and Designation Sight and rocket pods, the Apache could take 38 precision guided rockets plus eight Hellfires into battle.

APKWS low-rate initial production this year would have given the Army initial operational capability around 2007, but a budget decision early this year stopped work on APKWS after eight test firings. A restructured guided rocket program is being pursued by the Army Program Manager Aviation Rockets and Missiles. Click here for more Aircraft Survivability news from Rotor & Wing.

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