Big blue blanket

A diagram of the big blue blanket. American picket warships (destroyers) would use radar to detect incoming Japanese aircraft. They would then radio the position and course of the incoming aircraft to American fighters of the combat air patrol circling the main American fleet. Those fighters would then intercept the incoming Japanese aircraft long before they could attack the main American ships (carriers).

The big blue blanket was an air defense system devised by John Thach during World War II for protecting American warships from attack by Japanese kamikazes.