Patriot, as deployed in the Gulf War I, had certain modes where it would automatically engage, one of which was when it felt threatened by an anti-radiation (anti-radar) missile. Two marine pilots were flying together without IFF (Identification friend or foe) active. One had a malfunction and separated to land on an airfield defended by a Patriot battery. When he separated from his wingman, he looked to the Patriot radar like a separating missile. When he flew an approach directly at the radar he looked like an anti radiation missile. His wingman decided to follow him. It looked like a salvo of two anti radiation missiles. Patriot did what it was programmed to do. Thereafter, the air boss was the E-3 AWACS, and Patriot could only engage a target if authorized by the air boss.
Lonesome in Massachussets wrote: “Patriot, as deployed in the Gulf War I, had certain modes where it would automatically engage, ,,”
HAWK had automatic modes as well.
BTW, what about Fire and Forget missiles with lock-on after launch?