Air Force Bases

Nike Ajax System Operation

The Nike Ajax command guidance system received guidance information from a computer on the ground. Designed to engage faster and higher-flying aircraft beyond the range of conventional antiaircraft artillery, the Nike system depended on technological advances in radar and computers made during and after World War II.

A series of events preceded any missile launch. First, an Air Defense Command Post sent warning to the battery of an imminent attack. Sirens would send personnel scurrying to their assigned battle stations. At the launching area, personnel conducted last-minute prefiring checks and positioned the missiles on the launchers.

As personnel readied the missiles, the incoming aircraft was picked up on a longrange acquisition radar. For the Nike Ajax system, this radar was known as LOPAR for "Low-Power Acquisition Radar." The LOPAR search radar antenna rotated constantly at a predetermined speed. When targets appeared on the scope, the battery commander used "electronic interrogation" to determine if the target was friend or foe.

Once the LOPAR operator designated a target as hostile, this information was transferred to a target-tracking radar (TTR). The TTR determined the target's azimuth, elevation, and range, and then automatically provided that information to a computer for use in guiding the Nike Ajax missile. Once energized, the guidance computer received a running account of the target's changing position.

Adjacent to the TTR, the missile-tracking radar (MTR) locked onto the missile selected to perform the intercept. When the hostile aircraft came within the battery's range, the battery commander launched the missile. After producing 59,000 pounds of thrust within 3 seconds to push the missile off the launch rail, the missile booster dropped away. Having ignited, the missile accelerated through the sound barrier. Once the missile was in the air, the MTR received continuous data on the missile's flight. In turn, by receiving updates from the TTR, the computer generated course correction information that was transmitted to guide the missile toward the target. At the predicted intercept point, the computer transmitted a burst signal that detonated the three high-explosive warheads,

One of the major flaws of the Ajax guidance system was that it could engage only one target at a time. Also, when the system first deployed, there was no provision for coordinating fire between multiple batteries. Thus, several different batteries could engage the same target and allow other targets to pass through. To alleviate this problem, ARADCOM established command centers where incoming targets were manually plotted and engagement orders were passed to the batteries. However, the inadequacies of this voice command and control system became immediately apparent during defense exercises, which sent the Army scrambling for a new solution.

Introduced in the late 1950s the Interim Battery Data Link (IBDL) provided a "real-time" target data link between the batteries so that battery commanders could readily see what targets other batteries were actively engaging.

While IBDL was being deployed, the Army tested a successor system called "Missile Master" at Fort Meade, Maryland. After this system was proven within the Baltimore- Washington Defense Area, other major defense areas began receiving the Missile Master (AN/FSG-1) systems. Missile Master was the first truly integrating command and control system featuring automatic data communications, processing, and display equipment. By eliminating voice communications, this Martin-built system allowed an area commander to use all his batteries to engage up to 24 different targets.

Smaller defense areas with fewer batteries received another command and control system called the Battery Integration and Radar Display Equipment "BIRDIE" (AN/GSG-5).