Radar picket

A radar picket is a radar-equipped station, ship, submarine, aircraft, or vehicle used to increase the radar detection range around a force to protect it from surprise attack, typically air attack. Radar picket vessels may also be equipped to direct friendly fighters to intercept the enemy. In British terminology the radar picket function is called aircraft direction. Often several detached radar units encircle a force to provide increased cover in all directions. Airborne radar pickets are generally referred to as airborne early warning.

Radar picket ships first came into being in the US Navy during World War II to aid in the Allied advance to Japan. The number of radar pickets was increased significantly after the first major employment of kamikaze aircraft by the Japanese in the Battle of Leyte Gulf in October 1944. Fletcher- and Sumner-class destroyers were pressed into service with few modifications at first. Later, additional radars and fighter direction equipment were fitted, along with more light anti-aircraft (AA) guns for self-defense, usually sacrificing torpedo tubes to make room for the new equipment, particularly the large height-finding radars of the era. Deploying some distance from the force to be protected along likely directions of attack, radar pickets were the nearest ships to the Japanese airfields. Thus, they were usually the first vessels seen by incoming waves of kamikazes, and were often heavily attacked.

The radar picket system saw its ultimate development in World War II in the Battle of Okinawa. A ring of 15 radar picket stations was established around Okinawa to cover all possible approaches to the island and the attacking fleet. Initially, a typical picket station had one or two destroyers supported by two landing ships, usually landing craft support (large) (LCS(L)) or landing ship medium (rocket) (LSM(R)), for additional AA firepower. Eventually, the number of destroyers and supporting ships were doubled at the most threatened stations, and combat air patrols were provided as well. In early 1945, 26 new construction Gearing-class destroyers were ordered as radar pickets without torpedo tubes, to allow for extra radar and AA equipment, but only some of these were ready in time to serve off Okinawa. Seven destroyer escorts were also completed as radar pickets. The radar picket mission was vital, but it was also costly to the ships performing it. Out of 101 destroyers assigned to radar picket stations, 10 were sunk and 32 were damaged by kamikaze attacks. The 88 LCS(L)s assigned to picket stations had two sunk and 11 damaged by kamikazes, while the 11 LSM(R)s had three sunk and two damaged.

...
Wikipedia