The widow of a US Navy pilot who died when his fighter jet was struck by a Patriot missile during the 2003 invasion of Iraq has sued the air defence system’s maker, Raytheon Co.The lawsuit alleges the company was negligent in the design and manufacture of the Patriot system. It claims the Patriot was prone to malfunctions that misidentified US planes as enemy missiles that “occurred with alarming frequency and were well-known to Raytheon before the incident."