Seeking to avoid another friendly fire incident involving the Patriot missile system, U.S. Air Force pilots hunting for Iraqi missile batteries are now performing an additional procedure before pulling the trigger, Air Force Secretary James Roche said April 1.

Strike planes flying suppression of enemy air defense missions routinely lock on to potential targets by tracing signals from their radar systems. In Iraq, pilots are now instructed to shift to a second, more discriminatory system to confirm the enemy target, Roche said.

"We've gone back to look at our procedures to make sure that if something comes up we then do a double check," Roche told reporters at a Defense Writers' Group breakfast.

The procedure, however, likely is seldom used. Iraqi air defense batteries are firing unguided missiles, so there usually is no radar signal for coalition pilots to detect.