“This Is Only a Test”
Fifty years ago, cold-war games halted all civilian air traffic—long before September 11 did the same.
- By Roger A. Mola
- Air & Space magazine, March 2002
National Archives and Records Administration
(Page 2 of 7)
If the ground-based radars, airborne radars, and sea-anchored radar platforms called Texas Towers worked as promised, NORAD expected advance warning of 12 to 20 minutes should an "air-breathing" attack occur along a 5,000-mile line looking north, from the Aleutian Islands to eastern Greenland. Ears and eyes reached out 3,000 miles toward the Red Menace, with the ability to detect a reflecting surface of one square foot—a basketball, or in practical terms, the nose of a B-47-type target. The ICONORAMA at Colorado Springs, the movie-screen-size display tracking all aerial activity in North America, displayed the DEW and Mid-Canada Line blips—up to 95 percent of targets, head-on, flying between 200 and 65,000 feet, within radar line of sight out to 150 miles. Low-altitude detection, mainly by the DEW Line, was projected to be valid from the surface to 10,000 feet.
Data from the DEW Line was fed to the four-story blocks on Strategic Air Command bases containing the 250-ton IBM computer called Whirlwind II, each of which had 49,000 vacuum tubes housed in a bunker that was reinforced to resist all but a direct nuclear hit. Controllers had previously used slide rules and paper charts, marking flight trajectories in grease on Plexiglas boards. The New York Defense Sector at McGuire Air Force Base in New Jersey was the first to get the Semi-Automatic Ground Environment (SAGE), which was enabled by Whirlwind. The Federal Aviation Agency (as it was known until 1967) hoped that simulations like Sky Shield, combining Air Defense Command with its own surveillance and air traffic control radars, would meld military command with FAA personnel through a program called SATIN (SAGE Air Traffic Integration). Under SAGE, the 600 daily civilian flights approaching the continent could now be checked against their authorized flight plans before they crossed the Air Defense Identification Zone, a buffer zone of airspace extending from the nation’s borders and shores. If the flight path was maintained, the aircraft was, by definition, peaceful. If it strayed, within a tolerance for weather and pilot error, identification was attempted by radio. If that failed, within minutes an interceptor would scramble for a visual check.
After detection, an enemy bomber would be engaged by long-range manned interceptors and next by a Bomarc missile; if it still survived, the bomber would fly into range of Nike-Ajax and Nike-Hercules missiles.
The Department of Defense announced in late July 1960 that on September 10 it would mobilize an unprecedented number of combat aircraft in a training exercise so vast that it could succeed only if civil aircraft did not interfere. "Airlines will have about eight weeks notice to adjust their schedules and notify their reservation holders," read the DOD news release. "Sky Shield differs from earlier exercises in that it will involve the whole radar and electronics system used in air defense. However perfect any system may be, it cannot be relied upon until it has been thoroughly exercised.
"About 2,000 defensive sorties will be flown," DOD predicted. "Exercise forces will not be armed with nuclear weapons. No live ammunition will be used in any phase of the exercise."
Some 1,000 commercial flights would be delayed or canceled in the United States, and 310 in Canada. Nearly 700 private business and pleasure flights would be squelched. In addition, 31 international carriers would delay arrivals or departures until the all-clear.
On September 10, not 2,000 but 1,129 fighter scrambles were flown by some 360 interceptors against the SAC strike force of B-47s and B-52s, which simulated an "enemy" force of 310 bombers. Of the scrambles, 730 attempted to engage the bombers, while the rest cruised in patrol. Bombers split their missions between high- and low-altitude attacks with the two swarms converging on defenders. The missile force simulated engagements by 52 Bomarc, 254 Nike-Hercules, and 96 Nike-Ajax missiles.
In February 1961, William B. Becker of the Air Transport Association surveyed ATA members on how they had dealt with Sky Shield I: notifying passengers of the shutdown, juggling the rescheduled aircraft and crews, and changing reservations. "Estimated cost figures from only nine of the many air carriers affected totalled approximately one-half million dollars," he wrote. Reports from 14 airlines indicated that Sky Shield I, which had grounded commercial flights for six hours in the early morning, resulted in 182 flight cancellations and 100 schedule adjustments. Flying Tiger Line, which flew cargo at night, was hardest hit.