Gunship Sensors Optimized for Urban Warfare.

New sight targeting systems for Cobra, Apache, address fratricide concerns

Identifying ground targets at night never has been easy for helicopter pilots. Most night-vision sensor packages available on gunships today offer limited performance, which means that pilots must get close--within a few kilometers--to their targets in order to fire with accuracy.

Failure to do so could result in fratricide. More than a decade ago, a U.S. armored personnel carrier was struck by friendly fire from a U.S. Apache helicopter, during Operation Desert Shield, in the Persian Gulf.

But Pentagon planners now are focusing less attention on the problems of fighting in the desert, and directing their efforts to the challenges of urban warfare. In the foreseeable future, it is expected that the battles that U.S. troops will fight will be in urban environments, where civilians and military forces are not clearly separated, and where there are lots of corners for the enemy to hide. (related story, page 20)

The upshot, officials said, is growing difficulties for attack helicopter pilots operating at night.

The Marine Corps experienced these problems first-hand during an April 1999 deployment to Macedonia, in support of NATO'S air war over Kosovo. For that mission, the 26th Marine Expeditionary Unit (MEU) was equipped with four AH-1W Cobra attack helicopters and two UH-1N Huey utility choppers.

In Macedonia, those Marines saw the "urban nature of the operations we are involved in," said Navy Capt. Tom Curtis, program manager of Marine attack and utility helicopters. One lesson they learned, said Curtis, is that they "need better capabilities in precision targeting and positive target identification," in addition to speed and range.

Out of the last 253 Marine Corps deployments overseas, 238 involved "some sort of urban operation," Curtis said during a recent briefing to industry representatives.

The need for precision targeting capabilities is one of the driving forces behind a multi-billion dollar program to upgrade 180 Cobras and 100 Hueys during the next decade. These aircraft will be remanufactured and equipped with a new four-bladed rotor system, glass cockpits, new engines and gearboxes, among other upgrades. For Marine combat pilots, one of the most anticipated upgrades in the rebuilt Cobra--renamed the AH-1Z--is the nose-mounted target sight system, said Curtis.

The new target sight system is called Hawkeye, made by Lockheed Martin Missiles & Fire Control. The Cobra manufacturer is Bell Helicopter Textron. Lockheed received a $7.8 million contract to build five prototypes. The Marine Corps plans to buy 201 systems, at a unit cost of about $925,000.

Among the most significant technologies that Hawkeye brings is a third-generation forward-looking infrared (3rd Gen FLIR) sensor, said Mark J. Gibson, a former Cobra and Apache pilot who is now employed by Bell Helicopter Textron. The FLIR can see through haze and smoke and in complete darkness. Other Hawkeye components include large-aperture optics, a low-light color TV, a satellite-guided navigation unit and a laser rangefinder. The electronics are packaged in a five-axis gimbal, which helps provide a stable picture.

The current Cobra's night targeting system "bounces around," said Curtis. "It doesn't matter how good your sensor is, if it's been smeared by vibration."

In the revamped Cobra, pilots will see target images on a helmet-mounted display. TV cameras mounted on either side of the helmet will replace night-vision goggles. "The pilot can fly with his head up and out of the cockpit," said Curtis. Tracking systems allow the pilot to guide the weapon where he looks.

The benefit of using cameras instead of night-vision goggles is obvious, he said. Night-vision goggles are rendered ineffective, for example, when trying to see a vehicle that has its lights on. It's called "blooming effect." That is a drawback in urban operations, said Curtis. "When you look at a building and you get blooming, you can't see the details around the building."

As a result of the limitations in the current target sight system, crews may not be able to distinguish friend from foe, said Curtis. "Fratricide is unacceptable in any amount." Having advanced sensors and targeting devices not only helps prevent fratricide, but also saves ammunition, he added. "You don't want to waste a missile on a target you've already killed. You need to have good identification."

The Army also has attempted to address the fratricide concerns associated with targeting systems in helicopters. There is a program under way to provide a replacement for the Apache target acquisition designation sight/pilot night vision sensor (TADS/PNVS). The Hawkeye prime contractor, Lockheed Martin Missiles & Fire Control, also is developing the Arrowhead, an advanced targeting and navigation system for the Apache A and D models.

With Arrowhead, the Army opted for a 2nd Gen FLIR that will be used in both Apache and Comanche, its next-generation scout-attack helicopter.

According to Gibson, that was not a good decision. The 2nd Gen FLIR, be said, "is not nearly as capable as the 3rd Gen in the Hawkeye." Current Cobras and Apaches have 1st Gen FLIRs.

A 3rd Gen FLIR is a focal plane staring array. Older FLIRs are scanning arrays. There is an ongoing debate within the military scientific and industry communities on the merits of 2nd vs. 3rd generation FLIRs.

The "generation" of the FLIR does nor make a sensor more or less suitable for over-water operations, for example. It is the wavelength in which that FUR operates that determines its performance in different types of environments, Gibson said. The current Cobra night target system, the Apache TADS/PNVS and both the Comanche FLIR and Apache follow-on FLIR (Arrowhead) all operate in the 8-12 micron wavelength/band. "This makes them great for the desert, nor so great for high humidity or over-water operations," said Gibson.

The Hawkeye FLIR is a 3-5 micron (mid-wave) FLIR, which makes it more suitable for Marine combat missions, near the coast.

The Army chose the current Comanche package before the Hawkeye was available, said Gibson. "At that time, the 2nd Gen FLIR was state-of-the-art. It isn't any longer."

Both the Apache and the Cobra, with their current 1st Gen FLIRs, "are technologically limited in their ability to perform positive target identification," said Gibson. They require the pilot to maneuver the aircraft well within the weapons range of enemy anti-aircraft systems.

"Pilots don't like to do that, so they stand off as far as they can to engage their targets," he said. That's one reason the Army acquired the millimeter-wave Longbow radar for the Apache. The Longbow allows pilots to shoot Hellfire missiles from standoff ranges. But it does not provide positive friend-or-foe identification, explained Gibson.

To single out the target, the pilot either has to fly closer in and visually identify it, or depend on a human forward-air controller or another platform with better optics. "If it's the former, then fratricide becomes a huge issue," Gibson said. "The Marines chose the best FLIR available--one that allows them to stand off at the maximum range of their Hellfire missiles, do positive target ID and stay out of the threat's engagement range.

Charles M. Burke, manager of international business development at Lockheed Martin Missiles & Fire Control, defended the Army's choice of Arrowhead for Apache and Comanche.

It's important to note that, as far as the Army is concerned, 3rd Gen FLIR does not exist, he said. The Hawkeye array is a 640x480 InSb (Indium Antimonide) detector, which is considered high resolution by today's standards. The Army Night Vision Laboratory defines 3rd generation as 1,000x1,000, which is not available today.

Arrowhead is a scanning array, unlike the staring Hawkeye sensor. Because Apache's 1st Gen FLIR was a scanning array, said Burke, the Army "wanted us to upgrade it and keep the same form, fir and function, but improve the technology," so it did not want a staring sensor. The 2nd Gen FLIR, additionally, is priced more competitively because it is produced in larger numbers, which helps the Army save money, said Burke.

Compared to the current technology, he said, Arrowhead offers a "100 percent improvement in the ranges for target recognition." It exceeds the range of Hellfire (5-10 kin) under most conditions, except in blowing sand or monsoon-type rain. Lockheed Martin started producing the current TADS/PNVS in 1985. The company also makes the Longbow fire-control radar.

There is another reason why the Army wanted a scanning sensor, Burke explained. The Apache has two sensors: one is used for pilotage--to fly around the battlefield--and the other is for targeting. In a pilotage sensor, the refresh rate on a staring array is too slow, he said. "As you move your head from one side to the other, the staring array would not give you the resolution you need to fly safely." A scanning array, as the pilot's head moves from left to right, provides a greater refresh rate. "Staring arrays can do a very good job with targeting at distances, but if you move your head really quickly, you are not going to get as clear an image," Burke said.

Apache is the only helicopter where both pilot and co-pilot look through the same FLIR camera, he added. In all other attack helicopters, the co-pilot looks through heat-intensification targeting FUR and the pilot flies the aircraft with night-vision goggles.

The co-pilot gunner fires the missile, using the targeting FLIR. The pilotage system--which flies under all light conditions--is needed to get the helicopter into a position to fire the missile. To avoid the blooming effect, the Apache's pilotage FLIR uses heat-intensification sensors, so both pilot and co-pilot can "fly and fight together," said Burke.

In the Arrowhead, the targeting array has to function also as a back-up pilotage system, in case the main pilotage system is damaged. That means the targeting sensor needs to perform with the same resolution as the piloting sensor. Like the Hawkeye, Arrowhead provides improved stabilization against jitter, Burke claimed. Software improvements have helped eliminate the blooming effect in nighttime conditions, he added.

An Army study indicated that 50 percent of accidents experienced in the attack and reconnaissance helicopter fleet during the past decade were attributed to the poor performance of the night-vision goggles and the 1st Gen FLIR.

But Burke noted that, since that friendly-fire incident in the Persian Gulf--which happened in daylight--there has not been another case of fratricide with an Apache. Even with the improved Arrowhead, the pilot has to do visual identification. "With improved visual acuity, we've improved the pilot's ability to visually ID targets," he said. But there is no automatic way to identify friend or foe.

Lockheed Martin is under contract to build six Arrowhead prototypes. Burke expects production to begin by 2004. Arrowhead and Hawkeye both are competing head-to-head in the international market.