Vaunted Patriot Missile Has a 'Friendly Fire' Failing

Theodore Postol, a physicist at the Massachusetts Institute of Technology and co-author of an influential study criticizing the Patriot performance in the 1991 Gulf War, suggests that the problem may lie with the way the Patriot system interpreted IFF signals. With the Iraqi air force grounded, he said, the return signal "is never going to be a 'foe,' so there's no reason ever to fire at an airplane," he said. "These systems apparently didn't work."

Soldiers operate the Patriot battery -- which includes a command station, radar unit and launcher assembly that can hold as many as 16 missiles -- using computer displays that show digital maps of the sky. Icons indicating friend, foe or unknown move across the screen, much like in an air-traffic control system. When a target such as a jet, robotic drone or missile is confirmed, one or more intercept missiles are launched.

Tim Carey, vice president of the Patriot product line at Raytheon Corp., the prime contractor, said the system is designed to distill an accurate picture from complex and confusing information. For example, each battery relies on two operators to handle the high flow of battlefield data. "When things are hot" -- if a battle is raging -- "both soldiers have exactly the same display up, and they will work together to confirm the targets," Carey said.

The Army has deployed several versions of the Patriot system in Iraq and Kuwait. All the batteries now employ an enhanced radar system developed by Raytheon. Some of the batteries use a new missile -- the PAC-3 -- that vaporizes an incoming missile warhead by striking it with tremendous force, rather than with an explosive charge. A collar of 180 independently fired rocket motors guides the missile to its target.

Each Patriot missile costs as much as $2 million; a battery can cost $225 million. About 50 batteries were deployed during the Iraq war.

Cirincione and other independent missile experts believe that the changes made during the 12-year, $3-billion program to upgrade the Patriot system have never been fully tested.

Only four "operational" tests of the PAC-3 -- simulating some actual battle conditions -- have been conducted. Two of seven PAC-3 missiles destroyed their targets, one hit a glancing blow, and four others missed or failed to launch.

In the same tests, two out of three PAC-2 missiles scored hits. But in each of those cases, they destroyed a drone aircraft -- the slowest, most vulnerable target.