A number of problems with Patriot missile defenses and related systems contributed to three friendly fire deaths during the U.S.-led invasion of Iraq in 2003, the Pentagon has said.

Patriot batteries misidentified and shot down an American and a British fighter in separate incidents, leaving three air crew members dead. A Patriot system also mistakenly tracked another U.S. fighter, which bombed a radar in response. The incidents took place in March and April 2003.

http://www.iht.com/articles/ap/2007/10/16/america/NA-GEN-US-Qatar-Missil...