Command and Control

At the Massachusetts Institute of Technology (MIT), researchers concluded that the Whirlwind computer, originally built for the Navy as a flight simulator, could be used to automate air defense and early-warning tasks. Unlike computers that took days or weeks to perform calculations, the Whirlwind had been designed to operate in real time. After extensive testing by the Air Force, an updated version of the Whirlwind was chosen to serve as the heart of the Semi-Automatic Ground Environment (SAGE) — a centralized command-and-control system that linked early-warning radars directly to antiaircraft missiles and fighter-interceptors, that not only processed information in real time but also transmitted it, that replaced manpower with technology on a scale reminiscent of pulp science fiction. It was the first computer network.

Built during roughly the same years as the DEW Line, SAGE consisted of twenty-four “direction centers” and three “combat centers” scattered throughout the United States. The direction centers were enormous four-story, windowless blockhouses that housed a pair of AN/FSQ-7 computers, the first mainframes produced by IBM. They were the largest, fastest, and most expensive computers in the world. Each of them contained about 25,000 vacuum tubes and covered about half an acre of floor space.

Analog signals from early-warning radar sites were converted into digital bits and sent via AT&T’s telephone lines to SAGE direction centers, where the huge computers decided whether an aircraft was friend or foe. If it appeared to be an enemy bomber, the computers automatically sent details about its flight path to the nearest missile batteries and fighter planes. Those details were also sent to NORAD headquarters. Human beings would decide whether or not to shoot down the plane. But that decision would be based on information gathered, sorted, and analyzed by machines. In many respects SAGE created the template for the modern computer industry, introducing technologies that would later become commonplace: analog to digital conversion, data transmission over telephone lines, video monitors, graphic displays, magnetic core memory, duplexing, multiprocessing, large-scale software programming, and the light gun, a handheld early version of the mouse. The attempt to create a defense against Soviet bombers helped to launch a technological revolution.

Although dubious about the usefulness of SAGE, General LeMay thought that SAC’s command-and-control system needed to be improved, as well. He wanted to know where all his planes were, at all times. And he wanted to speak with all his base commanders at once, if war seemed imminent. It took years to develop those capabilities.

When SAC’s Strategic Operational Control System (SOCS) was first unveiled in 1950, its Teletype messages didn’t travel from one base to another with lightning speed. During one early test of the system, they were received almost five hours after being sent. And it could take as long as half an hour for the American Telephone and Telegraph Company to make the SOCS circuits operable. That sort of time lag would make it hard to respond promptly to a Soviet attack. Transmission rates gradually improved, and the system enabled LeMay to pick up a special red telephone at SAC headquarters in Omaha, dial a number, gain control of all the circuits, and make an announcement through loudspeakers at every SAC base in the United States. The introduction of single-sideband radio later allowed him to establish voice communications with SAC’s overseas base commanders — and with every one of its bomber pilots midair. The amount of information constantly streaming into SAC headquarters, from airplanes and air bases throughout the world, led to the creation of an automated command-and-control system that used the same IBM mainframes developed for SAGE. The system was supposed to keep track of SAC’s bombers, in real time, as they flew missions. But until the early 1960s, the information displayed at SAC headquarters stubbornly remained anywhere from an hour and a half to six hours behind the planes.