Business & GA, Embedded Avionics, Military

Guarding Against Threats

By By Frank Colucci | November 1, 2011
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The Rocket-Propelled Grenade (RPG) that claimed a U.S. Army Chinook loaded with Navy SEALS last August was a grim reminder that threats to battlefield rotorcraft are more than guided missiles. The Joint and Allied Threat Awareness System (JATAS) is meant to warn helicopter and tilt rotor crews of Man Portable Air Defense Systems (MANPADS), unguided munitions and telltale lasers.

“You take a lot of sensors and you put them into one JATAS sensor,” summarized Capt. Paul Overstreet, program manager for advanced tactical aircraft protection systems at the Naval Air Systems Command (NAVAIR). JATAS will also geolocate threats for networked forces. “That information will be on the mission computer, and you can shoot back or link it off to someone else.”

NAVAIR awarded ATK Defense Electronics Systems Division the JATAS Engineering and Manufacturing Development (EMD) contract in July and expects Initial Operational Capability with a dozen Marine Corps MV-22 tilt rotors equipped by summer 2015. ATK in Clearwater, Fla., teamed with BAE Systems in Nashua, N.H., to build JATAS prototypes during a competitive16-month Technology Development (TD) phase. The winning team must now productionize the system of sensors, control processor and warning algorithms on an aggressive EMD schedule. “We’re still engaged in combat operations, so there’s an urgency to get it out there as quickly as we can,” Overstreet said.

The last U.S. helicopter shot down by a shoulder-fired, infrared-seeking surface-to-air missile was an Army Chinook lost with seven lives in Afghanistan in May 2007. Unguided RPGs and gunfire nevertheless continue to claim aircraft and lives while evolving MANPADS grow more lethal. The first JATAS EMD system available for integration on the MV-22 should be delivered next fall for flight tests in 2013. The planned procurement baseline is 1,150 systems to outfit the MV-22B tilt rotors and AH-1Z attack, UH-1Y utility and CH-53K heavy lift helicopters of the Marine Corps, and the Navy’s MH-60R and -60S multi-mission helicopters.

For MANPADS protection today, Marine Ospreys, Cobras and Hueys, Navy Seahawks and Air Force Pave Hawks all rely on the ATK AN/AAR-47B(V)2 missile and laser warning receiver (MWR/LWR) integrated with flare and chaff dispensers. Laser warning cues combat crews to rangefinders, designators or missile command links. A software upgrade now entering the fleet gives the proven MWR/LWR Hostile Fire Indicator (HFI) capability to warn of tracer rounds and RPGs. However the Navy AAR-47, like the BAE AAR-57 Common Missile Warning System (CMWS) used by the Army, spots rocket plumes and muzzle flashes with staring ultraviolet (UV) detectors prone to false alarms, and it can localize the threat only by quadrant.

Big Marine Corps CH-53Es took the Department of the Navy’s Large Aircraft InfraRed CounterMeasures system (DoN LAIRCM) to Afghanistan to confound MANPADS with Directed InfraRed Countermeasures (DIRCM). To aim laser energy at the seeker dome of an incoming missile, the Northrop Grumman DoN LAIRCM introduced two-color imaging infrared (IR) detectors that generate precise Angle of Arrival (AoA) information.

“The information is much more precise, obviously lower false alarm rates,” said Overstreet. “That will translate to a much better display in a glass cockpit.”

Bill Kasting, ATK Defense Electronics Systems vice president and general manager explained, “One of the unique aspects of the two-color IR is you have multi-spectral capability that lets you discriminate against false alarms much better… That’s one of the challenges of missile warning. A pilot doesn’t want to deal with a lot of false alarms.”

JATAS TD confirmed two-color IR technology was less prone to false alarms than UV detectors and more likely to detect hostile fire signatures at greater ranges amid environmental clutter. “There’s a lot more out there in the UV spectrum that we have to deal with,” Kasting said. “The UV clutter is more than what we’ve seen in the IR spectrum.”

Though the DoN LAIRCM suite enabled Marine heavy lift helicopters to re-enter areas once denied to them by the MANPADS threat, the installed system weighs more than 300 lb. Northrop Grumman failed to win a JATAS Technology Demonstration contract with existing LAIRCM sensors. Overstreet explained, “JATAS will bring equivalent capability but in a smaller package and integrate laser warning, and it integrates HFI from a baseline standpoint.”

The new warning receiver is meant to interface with fielded jammers or the coming Common Infrared Countermeasures (CIRCM) system (Avionics, November 2010, page 20).

While the Army manages CIRCM development, the Office of the Secretary of Defense directed the Navy to develop the next-generation warning receiver. “They essentially gave us the lead on missile warning and the Army the lead on the infrared countermeasures system,” Overstreet said. JATAS requirements consequently call for an Open System architecture able to work with the glass cockpits and integrated subsystems of many different aircraft. “All our platforms now that we’re targeting all have advanced cockpits,” said Overstreet. “They typically don’t have dials. We’re spending the money to integrate it and put it under the glass.”

Like the Navy and Marine Corps, the Air Force and allied nations are expected to integrate JATAS on multiple platforms. The new warning receiver cannot be offered for Foreign Military Sales (FMS) until operational testing is complete, but according to Overstreet, “We have a lot of FMS customers on the ‘47 side… so they look like likely customers.”

The U.S. Army has CMWS on more than 2,000 aircraft and may ultimately put JATAS on newer platforms. Navy and Marine jets are not part of JATAS plans.

“IR sensors don’t seem to be a critical requirement for fast-movers,” Overstreet said. “The threat of a MANPADS is not something they worry about too much.”

Technology Developed

JATAS prime contractor ATK teamed with BAE Systems about four years ago to develop a successor to the AAR-47. ATK is responsible for overall system architecture, integration and testing; BAE provides the control processor, warning algorithms and logistical planning. “The internal elements of the core processor are common to the CMWS,” said BAE JATAS program manager Sunil Sadhwani. “The physical box is unique. The heart of the processing is identical, which makes it a mature design with mature manufacturing processes.”

However, JATAS algorithms are different from those in CMWS. “Certainly, there’s more information you’re processing, the amount of data you get,” said Sadhwani.

JATAS competitors ATK and Lockheed Martin both bought detector arrays from DRS Infrared Technologies. “We went through a series of trades to verify that the two-color IR provides better detection performance over a sensor in the UV spectrum,” recalled Kasting. ATK tested prototype hardware in laboratories and on a rented helicopter to validate simulation models. “It’s very tough to get live-fire performance.”

NAVAIR flew the JATAS detectors on an H-60 from Fort Belvoir, Va., up and down the U.S. east coast to characterize challenging IR clutter. Simulated MANPADS, RPG and gunfire signatures were superimposed on real background data to maximize confidence in JATAS simulations. “If someone in Philadelphia had taken a shot at us, we could have detected them,” Overstreet said.

Helicopter applications with rotor flicker, vibration and temperature extremes also pose special challenges for a missile warning receiver. “When you get on the platforms, you learn things you didn’t expect,” Sadhwani said. “The rotary wing environment is something we’ve learned a lot on with the CMWS. That know-how is something we bring forward on the JATAS in the EMD phase.”

ATK tested its two-color IR solution at Naval Air Warfare Center Weapons Division China Lake, Calif., with an unmanned Seahawk running on an elevated platform the so-called “helo on a stick.” Live fire simulations around the test helicopter mimicked threat signatures. “There’s still a lot of emphasis on the missile warning, even though recently the greatest threats have been the hostile fire,” noted Kasting. “The guided missile threat is still a very real threat and a lot more accurate.”

The JATAS Technology Development system used a brassboard control processor and existing sensors with the same core IR technology. “The system that we used looked very different from the actual JATAS,” Kasting said. However, an integrated sensor built during the TD phase came close to JATAS production form, fit and function. JATAS system weight is expected to be about the same as that of the AAR-47B(V)2-HFI today, and according to Kasting, “One of our strategies was to build JATAS in the same physical footprint for easy integration onto the current aircraft.”

Open for Integration

JATAS integrates the control processor with multiple sensors to provide all-round coverage. The MH-60R and -60S will get four sensors while the UH-1Y, AH-1Z and CH-53K will receive five to look around and directly below the aircraft. The MV-22 is expected to integrate a sixth sensor for topside coverage. In each case, JATAS makes use of existing databuses, mission computers and cockpit displays, and it must accommodate evolving threats. “One of the key aspects of our offering is it’s based on an open architecture which will allow for easy insertion of upgrades in the future,” explained Kasting. Open hardware and software standards, including Application Protocol Interfaces, are also necessary to integrate JATAS on totally different aircraft with different architectures. “It’s not plug-and-play for anything… We’re giving the Navy access to our architecture and our APIs that define the interfaces.”

“There are a thousand different definitions of what Open Architecture does. From our standpoint, it was to integrate [JATAS] with any countermeasure that existed out there or any future countermeasures, and on all the platforms, said Overstreet. “We own the data rights for JATAS to improve the software… Controlling the ICD [Interface Control Document] allows us to integrate this on anything.”

JATAS EMD will not develop new cockpit displays. The most basic integration may use the existing AN/APR-39 radar warning receiver as a bus controller and display head. The MV-22 will post JATAS symbology on multifunction displays. “It’s a much more advanced integration as we get away from ‘39 to mission computers and cockpit displays,” said Overstreet. Future integration may tie JATAS to helmet displays like those in the AH-1Z attack helicopter.

Advanced system integration may also make JATAS threat information available to other players in a network-centric battlespace. “The thought is ‘how do we get it off-board?’ Do we use some of the Blue Force Tracker link or some of the LINK-16 capability in the V-22?” Overstreet explained.

Last April, the CORPORAL (Collaborative On-line Reconnaissance Provider/Operationally Responsive Attack Link) demonstration at Yuma Proving Ground linked the location of a simulated MANPADS threat detected by a testbed Huey to the targeting pod on a Harrier jet. The more immediate need is to productionize JATAS for combat aircrews.

“The biggest challenge is meeting the schedule. It’s a pretty aggressive schedule, and we’re trying to deliver hardware to the Navy,” said Kasting.

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