To Fire or Not? High-Tech Puzzle in Sky

In the night sky over Kuwait, the pilot of a tank-hunting A-10 “Warthog” stares intently at a tiny, green screen in the center of his cockpit, looking for a telltale glow of white.

Millions of dollars worth of Pentagon hardware--satellites, J-STARS targeting aircraft, high-flying spy planes and low-flying observation turboprops--led him to this corner of the desert, where his spotters believe Iraqi tanks and artillery pieces are entrenched on the ground.

But as his attack plane flies toward the marker of a white phosphorus rocket loosed by a spotting plane in the desert night, the pilot must make up his own mind: Is the faint white outline on his screen the infrared glow of a tank’s steel skin, still hot from the day’s sun, or is it something else? A decoy? A tank already destroyed? Something he can’t imagine?

He has only seconds to make the decision before firing a deadly--and expensive--heat-seeking Maverick missile, or passing over the target and returning to his base.

This hypothetical pilot’s dilemma reflects the staggering difficulties facing the fliers who sweep over Iraqi positions every night, seeking to identify and destroy thousands of Iraqi tanks, armored vehicles and artillery scattered over the desert.

How well they do in this second phase of the Persian Gulf War, which followed an initial wave of aerial attacks on strategic military and industrial sites in Iraq and Kuwait, could determine how many allied troops survive when the seemingly inevitable ground war begins.

“The weapons are only as smart as the people who are using them,” said Maj. Dick Cole, an Air Force public relations officer and pilot. “You can build all this great technology into a weapons system, but ultimately it’s a human call.”

The latest reports indicate that the intense assault on Iraqi armor is paying off. U.S. military officials said this week that allied pilots have destroyed nearly a third of Iraq’s tanks in the Kuwaiti theater--about 1,300 out of 4,280. In addition, the attacks have knocked out 800 of 2,870 armored vehicles and 1,100 of 3,110 artillery pieces, officials said. But it has taken weeks of aerial warfare and thousands of bombing sorties to inflict that damage, and the job is far from finished.

“It’s a long and difficult task,” said R. B. Costello, a former undersecretary of defense who is now a senior fellow at the Hudson Institute, a conservative think tank.

An Air Force pilot who flies an observation plane for tank-hunters put it this way: “It’s kind of like running around your kitchen crushing cockroaches. You stomp some and they move a little bit, but every time you hit one, you are getting one more. We are getting rid of them slowly but surely.”

Analysts said the Iraqi armor, much of it buried in sand, camouflaged and ringed by decoys, is hard to find and, once found, harder to destroy. Stationary objects, especially when they are nearly buried, pose problems for all but the most sophisticated radar. And infrared sensors that identify objects by detecting the heat they emit have trouble finding tanks whose engines are not running.

Even after the missiles are fired at their targets, the best of the high-tech allied gear usually is unable to determine whether a specific target is permanently out of action.

As long as the Iraqi equipment stays put, entrenched in earthen berms, “the problem is . . . you keep killing the same thing,” said Sam Gardiner, a retired Air Force colonel and military historian specializing in air campaigns. “How many tanks do we say we have killed? I wonder how many of those have been killed more than once. . . .

“You always overestimate the impact” of an air campaign, Gardiner said. “I can’t think of a historical example where we’ve looked at target damage from the air and underestimated it.”

In past weeks, military commanders had said they wanted to take out half of Iraq’s tanks and artillery before launching what is likely to be a bloody allied ground assault to drive Iraqi forces from Kuwait. But in recent days, they have backed off from specific numbers.

In the end, said Charles Myers, a military analyst who once served as director of air warfare for the Department of Defense, “Your success in killing them will be determined only when you attack.”

In the meantime, the night skies over Kuwait and Iraq are filled with tank-hunting aircraft, including:

* The A-10. Dubbed the Wart-hog because of its heavy armor, deadly 30-millimeter, rapid-fire cannon and relatively slow speed of 400 m.p.h., the aircraft was designed for close air support during armored battles--in daylight. Its pilots only recently have trained to hunt in the dark. First produced in the early 1970s, the plane has no radar. Pilots rely on spotting planes and infrared sensing devices mounted in the A-10’s Maverick missiles to target enemy armor.

* The Army AH-64 Apache attack helicopter. Equipped with a 30-millimeter gun and laser-guided Hellfire missiles, the Apache is particularly effective in the dark because of its sophisticated night vision system. A device on the pilot’s helmet directs an infrared sensing pod to follow the pilot’s line of sight as he seeks to identify targets.

* The F-15E Strike Eagle: This state-of-the-art fighter can fly at twice the speed of sound and carry nearly 25,000 pounds of weapons. Its primary function is to intercept and shoot down enemy aircraft. But its precise infrared targeting system and laser-guided bombs make it useful in anti-tank warfare.

In addition, F-111 fighter-bombers and Navy A-6 attack aircraft on occasion have been sent to strike Iraqi tank and artillery positions. Huge B-52s, capable of destroying wide expanses of desert terrain with carpet bombing, have been called into service when allied intelligence has identified concentrated forces of tanks and artillery.

Before they can attack the Iraqi tanks, however, allied airmen must find them. It has proven a daunting task. Many targets are scattered and nearly covered by sand. Inflatable tank decoys, many covered with metallic paint to deceive radar, have made the task all the more taxing.

“If it isn’t moving, that makes life really difficult,” said one military analyst.

Spy satellites, said to pass over the Kuwaiti battle theater at least 12 times a day, can gather optical and infrared images of the desert landscape below. But their pictures are of limited value in targeting tanks and other armored vehicles; they are intended to detect mass movements of troops and armor, not individual pieces of equipment.

The Pentagon has not acknowledged whether the TR-1, successor to the high-flying U-2 spy plane, is deployed in the Persian Gulf. But several analysts said they would be surprised if the long-winged aircraft filled with electronic imaging systems were not flying over Kuwait and Iraq.

Iraqi prisoners of war also can be helpful. And so can commandos--greasepaint and dagger guys, one analyst called them. Most of the military experts said allied commandos almost certainly are scouting tank and artillery positions inside Kuwait.

Of more immediate assistance are two Joint Surveillance Target Attack Radar System aircraft operating in the Gulf. The new planes, barely out of the prototype phase, are to ground forces what AWACS radar planes are to aircraft.

The J-STARS, as they are known, circle over Iraqi territory, beaming a new kind of side-viewing radar from under their fuselages that can produce near-photographic quality images of targets up to 200 miles away. Those images can be directly transmitted to the ground, so controllers can direct air strikes by radio as they watch the J-STARS radar displays.

The information also can be relayed to slow and low-flying observation aircraft, such as the OV-10, a turboprop plane whose two-man crew can fire rockets or flares to identify targets they have spotted.

The synthetic aperture radar installed in the J-STARS and TR-1s is much better at identifying stationary targets than is conventional radar, said the Air Force’s Cole. But the new radar is not perfect. If a tank is buried in the sand up to its turret, “you may get some return off the metal that’s exposed, but under the circumstances, you’re better off using infrared,” Cole said.

The infrared sensing systems in all the tank-hunting aircraft rely on the same principle. Heat gives off invisible rays of light that can be “seen” with infrared sensing equipment.

In a ground battle, infrared can be used to direct missiles at the hot engines of tanks churning through the desert. But when the tanks are entrenched in the sand, infrared sensing becomes a tricky matter.

The infrared display screens inside A-10s and other aircraft show heat sources as white patches on a field of green. The best time to detect entrenched tanks is in the early part of the night, when the skin of the tank has not cooled to the temperature of the surrounding sand.

Of course, pilots can always get lucky. “At this time of year, when it’s cold in the desert, you may hope that those guys (in the Iraqi tanks) fire that mother up to get some heat inside. They have to exercise some discipline not to do things like that,” one Air Force officer said.

The decision to fire is up to the pilot. But even if he believes he has positively identified the target, a hit is far from assured. Sand can absorb much of the shock of explosives and slow the hardened, 30-millimeter shells fired by the A-10. Tanks are much smaller targets than bridges. The margin of error is reduced proportionately.

Some of the more advanced Iraqi tanks, the T-72s purchased from the Soviets, for example, are equipped with reactive armor--small explosives strapped to the tank that blow up when hit by incoming missiles. The explosion diffuses the anti-tank weapon’s white-hot chemical plasma, which would otherwise burn through the armor to allow the force of the blast inside.

The Iraqis have made damage assessment all the more difficult by lighting pots of oil atop tanks that have not been hit, and setting off smoke flares.

In the end, the decision to end the air-only assaults and launch a ground-based offensive will be a judgment call, many of the experts said.

“We’re doing well so far,” said one analyst with close ties to the Pentagon. “As long as every day they are weighing in with another couple of hundred of fighting vehicles killed, we haven’t reached the point where this isn’t a worthwhile proposition. Carry on.”

HUNTING BURIED ARMOR Allied pilots face tremendous difficulties in their nightly missions to identify and destroy the thousands of Iraqi tanks, armored vehicles and artillery in the desert. Although they are assisted by millions of dollars in sophisticated hardware, the pilots still must make the final call: Is that faint outline on the screen the glow of a tank, a decoy, or a destroyed target? The Problems

DETECTION Many of the Iraqi tanks and armored vehicles are buried in sand, camouflaged and ringed by decoys. Stationary objects are difficult for all but the most sophisticated radar to find. Infrared sensors that identify objects by detecting heat have trouble finding tanks that are not runing their engines.

DESTRUCTION The most reliable signs of a hit are smoke and fire. But the Iraqis routinely set fire to pots of oil placed on the decks of tanks and set off smoke bombs to simulate a successful hit.

CONFIRMATION The only true test of a kill is whether a tank, artillery piece or armored vehicle is no longer able to shoot or move. Until a ground war begins, that question cannot be answered.