AT 8:53 A.M. ON SATURDAY, OCTOBER 14, 1961, Pacific Air Lines flight 715 from Sacramento rolled to its gate at Los Angeles International Airport and shut down its engines for 12 hours. At ticketing posts, a corps of temporary guides straightened their "World Way Blue" uniforms and accepted 50 cents for 20-minute tours of the new passenger terminal and the ramp. Inside the Pan Am 707 Jet Clipper Liberty Bell, stewardesses poured fresh Hawaiian fruit juice.

At every gate across the airport, airliners were receiving visitors but not passengers. United showed off its DC-8 and Boeing 720 jets, Convair 340, and Douglas DC-7A cargoliner. Bonanza opened its Fairchild F-27; Pacific Air Lines a Martin 4-0-4, and National Airlines a Lockheed Constellation. On the LAX ramp sat Western Airline’s tiny 1926 Douglas M-2 biplane.

LAX was only one of many airports to shut down. Nationwide, 50 civilian airports held open houses. But most passenger terminals just turned off the lights. Except for aircraft in Hawaii, the entire U.S. and Canadian commercial fleets and all civilian aircraft were grounded.

On that day, and on two others in the early 1960s, the airliners had to make way for waves of B-52 and B-47 bombers that were to cross from Canada into the United States and enter the continent from the coasts in a simulated Soviet nuclear attack. The three simulations, known as Sky Shield, were training exercises for the personnel, communications, and radar detection systems of North America. The plan was to make sure that the bombers were detected by radar and other early-warning systems, that interceptor and missile squadrons would be alerted and scrambled, and that the United States would remain able to strike back.

Operation Sky Shield II, which ran for 12 hours in October 1961, was the second time—and the longest—that U.S. civil air traffic had been grounded. The first was Sky Shield I, run on September 10, 1960, from 2 a.m. to 8 a.m. Eastern Daylight Time. The third and final time—until last September—was Sky Shield III: five and a half hours beginning at 3 p.m. EDT, September 2, 1962.

In 1951, 30 radars—the Pinetree Line—were constructed along the U.S.-Canada border. By 1954 Pinetree provided early warning of threats and control of friendly aircraft. In 1953, the first station of the more capable Distant Early Warning Line opened at Barter Island, Alaska. By 1957, nearly 60 DEW Line radars were installed 100 to 500 miles apart, within two degrees of the 69th parallel from Cape Lisburne, Alaska, to Cape Dyer, Baffin Island. The new Mid-Canada Line, which ran along the 55th parallel from British Columbia to the Labrador Sea, employed 90 unmanned stations consisting of an electronic "trip wire," an application of the Doppler effect, to detect aircraft.

Continental air defense seemed technically capable, but, untested by war, its true reliability was unclear. General Earle Partridge, commander-in-chief of North American Air Defense Command, hatched a plan for the first live test of the entire continental air defense force. Operation Sky Hawk was set for September 1959 but canceled days before, under the new NORAD commander, General Laurence S. Kuter. Would-be participants were advised to destroy all records. Representatives of the U.S. President, the Air Defense Commands of the United States and Canada, and the Canadian Chiefs of Staff Committee revisited the plan at Camp David, Maryland, on November 7, 1959, agreeing to the first (new and improved) joint exercise.

In October, the Ballistic Missile Early Warning System, which consisted of both detection and tracking radars, opened at Thule, Greenland. Detection radar was a fixed fan parabola, 165 feet high and 400 feet long—a football field on its side sending an invisible "V" 2,000 miles north toward the Soviet Union. The screen could withstand earthquakes and winds of 180 mph. Within the installation’s radomes were 55-ton tracking radars, which followed objects horizon to horizon.

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.

Nonetheless, Becker reported to the FAA, ATA members would support NORAD: "The airlines will continue to cooperate to the fullest extent where military requirements dictate the necessity. In the event that an exercise of the magnitude of Sky Shield is justified in the future, we strongly urge that a minimum of 90 days’ advance notice be given. The exercise should be conducted on Saturday night-Sunday morning of a three-day holiday weekend."

Pleased with the cooperation from the FAA during Sky Shield I, NORAD’s General Kuter wrote to thank agency administrator Najeeb Halaby, who was already elbow-deep in planning for Sky Shield II. Halaby responded, "I am informed that upwards of 2,500 U.S. and foreign commercial flights and some 125,000 passengers may be affected together with a large number of private pilots. I will be happy…to inform these people of your appreciation for the contribution they are making toward the defense of the North American continent."

One channel Halaby had to pilots was the Aircraft Owners and Pilots Association, which published in the August 1961 issue of its Confidential Newsletter a paragraph about the continent-wide exercise. AOPA’s more comprehensive Pilot magazine did find space to mention general details and grounding requirements in local time zones. "Don’t Forget Sky Shield," it began. "If you’ve planned a flight for Oct. 14 or 15, better look at the clock before you take off."

More than 50 U.S. fighter-interceptor squadrons would participate, including those equipped with McDonnell F-101B Voodoos, Convair F-106 Delta Darts and F-102 Delta Daggers, Lockheed F-104 Starfighters, Northrop F-89J Scorpions, and Douglas F-4D Skyrays. Just over a thousand crews were on full alert. Across the continent some 150,000 airfield and flying personnel and 50,000 more in close support would also play a part, spanning NORAD, the U.S. Air Force, Army, Navy, Air National Guard, and the Royal Canadian Air Force. Navy picket ships and blimps bobbed off both coasts.

In Europe, NATO allies had already launched Operation Seven Pillars, a simulated strike of 40 atomic bombs followed by a numbing 22 hours of civil defense exercises. At coordinated times, defense officials opened envelopes containing simulated readouts of radiation levels, trying to determine the intensity of the blasts and their fallout patterns.

Like all NORAD exercises, the phases of Sky Shield II were transmitted to Royal Canadian Air Force stations by secure media, but in case of intercept, not the details. Operations were given RCAF code names that were worthy of Maxwell Smart. Planning conferences included Trusted Agents. Final pre-event checklists were dubbed Double Take A or B. The harried, last moments: Fast Pace. The Go hour: Cocked Pistol. Various milestones were designated Big Noise A or B and so on, through Fade Out.

On October 14 at Naval Base Argentia, Newfoundland, WV-2 Super Constellations of the VW-11 and VW-13 squadrons were pulled from the hangar as their crews plotted flights for mid-level surveillance over the Atlantic barrier of the Distant Early Warning Line. Aloft, the U.S. Navy provided sea flanks to lengthen the DEW Line with radar-equipped WV-2s, nicknamed Warning Stars, along the coast.

At Building P-4 of Ent Air Force Base in Colorado Springs, General Kuter sat before ICONORAMA. Kuter was responsible for all air defense in the United States (except Hawaii), Canada, and the coasts of both nations out to 150 miles.

At Seymour Johnson Air Force Base in Goldsboro, North Carolina, Captain Roland C. Starke Jr. reviewed the crew assignment. The B-52G was filled with 215,000 pounds of fuel while his seven crew members boarded. As Pogo 22, Starke would flank Pogo 13 for three hours of flight in radio silence as part of the code-named White Cell in order to rendezvous with one of three KC-135 Stratotankers, east-southeast of Newfoundland. Once refueled, the aircraft were to fly south toward Bermuda, then west for a simulated Soviet bomber run.

At McGuire Air Force Base in New Jersey, the war came down to single letters. Beginning at 1 p.m., the letters F for Friendly and K for Faker waltzed across the dull red of 106 cathode-ray tubes within the bunker’s two-foot-thick walls. At full tilt, the Whirlwind II computer tracked 400 aircraft at once, sputtering 65,000 calculations every 15 seconds. Controllers pointed an aluminum light gun at each blip and squeezed, marking the blip P for pending. If the blip’s track matched the expected flight plan, the P changed to F or K. "We’ve had it pretty heavy," Brigadier General Gilbert L. Pritchard, commander of the New York Air Defense Sector, told a cluster of reporters invited to McGuire. Pritchard said the simulated attack flown by B-47s, B-52s, and RAF Vulcans had been "pretty near continuous" since radar first detected an enemy at 1:45 p.m. "The attackers are coming over the top [the Arctic] and making end runs in off the Atlantic." Detected but unseen: Dark rain clouds enveloped New York City.

The wave of B-47s at low altitude showered pods of chaff—filaments coated with aluminum or zinc designed to overwhelm radars—while B-52s between 35,000 and 42,000 feet swept from the north through central Canada and diverged to the northeast and midwest population centers and along the West Coast as far as San Francisco.

In Colorado Springs, British Air Marshall Sir Kenneth B.B. Cross of the Bomber Command and Sir Wallace Kyle, chief of the Royal Air Force technical training command, sat with General Kuter. The Royal Air Force had provided eight delta-wing Vulcan bombers to mix with NORAD forces, posing as Russian heavies. They topped the attacking force at 56,000 feet.

Shortly before 2 p.m., interceptors had sprung for the B-52s. Only the first Vulcan in the cell of bombers was detected by an F-101. At 2:02 p.m., the voice of an Air Force colonel reached the Boston Sector: "Gentlemen, we shot down our first enemy." Near Goose Bay, Labrador, the Vulcan became the first "kill" of Sky Shield II. The remaining Vulcans swept unmolested through eastern Canada to land at Stephenville, Newfoundland, for debriefing and bragging rights.

Captain Starke’s B-52G and his cell of bombers refueled at 3 p.m., then turned southwest, toward their strike zone, a corridor between New York City and Philadelphia. The bombers flew in lateral formation, 10 miles apart, with Starke most northerly. He made radio contact with his left flank as late as 4:15 p.m. as the formation descended through clouds to 1,000 feet above the water.

On the east coast, jet fighters scored kills as far as 350 miles out in the Atlantic, the presumed maximum range for a Soviet release of air-to-surface missiles. But most engagements were over or near major cities. "Sonic booms caused the customary surge of phone calls to newspapers, radio stations and police," reported the New York Times. Chaff fell on thousands of houses, fields, and factories, prompting more panicked calls.

At the airports holding open houses, the public and airport staffs partied on. Los Angeles International hosted 40,000 visitors by day’s end, while workers seized upon the lull to complete the installation of a new air traffic control tower. At San Diego’s Lindbergh Field, maintenance workers shut down terminal power to perform 12 hours of repairs in the dark corridors, while outdoor temperatures broke 107 degrees. Across San Diego at the Mission Valley Inn, Pacific Southwest and American Airlines held a crew luncheon and pool party.

At Chicago’s O’Hare, Eastern, American, and Continental swung open the doors to their Boeing 707s and 720Bs. Trans World Air Lines presented its Convair 880, and United, its new Sud-Aviation S.E. 210 Caravelle twin-jet from France. At Chicago’s Midway, American, United, and TWA displayed Douglas DC-6s and -7s. O’Hare began operating its $4 million communications center. Following Sky Shield II, the cost of calls between Chicago exchanges and O’Hare was reduced from 15 to 10 cents for the first five minutes.

From 1 p.m. to 1 a.m. Eastern time, 2,900 commercial flights were canceled or delayed. At the three New York City air terminals, Newark, LaGuardia, and Idlewild, 955 arrivals and departures, affecting 26,800 passengers, were scrubbed.

The release of chaff ended one hour before the conclusion of the 12-hour exercise. Yet it fluttered down throughout the morning darkness, even as airliners began to resume service. Airliners stacked on taxiways conducted preflight checks; tower controllers nationwide directed flights to their runway thresholds to hold for the all-clear. At 1:07 a.m., after verification, a DC-8 departed Idlewild.

As of daybreak on Sunday morning, October 15, Captain Starke’s B-52G from Seymour Johnson Air Force Base remained missing. A vast search triangle was set up 600 miles from New York. As late as 12:15 a.m. on October 17, a Coast Guard cutter chased a reported orange flare. The crew of eight was eventually presumed lost at sea, the only casualties of the three Sky Shields.

General Laurence Kuter was quoted in media ranging from Air Force Magazine to the Chicago Tribune, calling Sky Shield II "the greatest exercise in information analysis, decision-making, and action-taking in continental aerospace defense in all our history." But Kuter deflected calls for a box score, reiterating that Sky Shield’s intent was, "by no means, a contest between offensive and defensive forces. Bombers presented themselves as targets and the object was not to ‘shoot them down,’ but to practice and train personnel in the use of the system." Sky Shield I had seen 1,129 sorties, but Sky Shield II bettered that by 50 percent.

Kuter added, "The many restrictions imposed in the interest of flight safety, and the leaving out of simulated nuclear detonations and other battle damage, served to distort many of the results." The Department of Defense refused to release an analysis or even to acknowledge that it had measured in any detail its radars, intercepts, and systems.

Quietly, NORAD produced an exhaustive report, presenting it to the Joint Chiefs of Staff before filing it in secure archives. A quarter-century later, the defense department ruled that as a bi-national command, NORAD could deny requests generated by the Freedom of Information Act. Finally, in 1997, most but not all of the Sky Shield results were declassified.

Had Americans known NORAD’s conclusions, they might have ducked and remained covered. Nearly one-half of enemy flights at low altitude had escaped detection. Of those initially detected, 40 percent then eluded tracking radar by changing their formation shape, size, or altitude. All told, if Sky Shield bombers had been Soviet bombers, no more than one-fourth would have been intercepted.

During all three Sky Shields, friendly units had posed as the enemy. Yet the participants had acted too much like, well, the enemy: flying lower than preauthorized, and flying in patterns that deviated from their assignments, a practice that required scrambles of the reserve force to identify the "unknowns."

The remote radar stations, though, considered the most vulnerable of the far-flung system, survived every simulated ground attack.

The Distant Early Warning and the Ballistic Missile Early Warning System lines had been penetrated by enemy cells of up to four aircraft, despite flying inbound at the system’s best tracking altitude, 35,000 to 40,000 feet. Low-altitude flights had been defined as anything below 5,000 feet, but NORAD acknowledged that a real enemy would fly lower, where continental radar was weakest.

The SAGE system tracked less than one-third the total mileage flown within radar coverage. NORAD had prepared for an assault with advanced electronic countermeasures, but it was the low-tech chaff that degraded SAGE—to the point where manual tracking was required, leaving the enemy obscured until well within bomb-release lines.

In Sky Shield III, which ran for five and a half hours on September 2, 1962, NORAD and the FAA realized their full vision for the continental plan to safely ground civilian aircraft during a nuclear strike. At 3:05 p.m. Eastern time, the Air Force launched 319 T-33 light jets, 263 in the U.S. and 56 in Canada, from random and unannounced locations. As the alert horn sounded, FAA controllers hustled to get them to civil airports far from the metropolitan targets that were presumed to be under mushroom clouds. All T-33s were on the ground in Canada within 49 minutes, and in the United States within 72 minutes.

Before the all-clear had sounded, 1,800 scheduled airline flights in the United States and 130 more in Canada lay idle, as did 31 foreign airlines. The cost: $1 million.

In 1963, NORAD planned to run Sky Shield IV. SAC officials objected, saying that they got better and cheaper training during focused, regional simulations. A round of limited, quarterly maneuvers called Top Rung began in fiscal year 1964.

On September 25, 1961, President John Kennedy had stressed the gravity of the Communist nuclear threat to the United Nations General Assembly. But Kennedy added that it was terrorists and fanatics, more than superpowers, that threatened national defense: "Terror is not a new weapon. Throughout history it has been used by those who could not prevail, either by persuasion or example. But inevitably they fail, either because men are not afraid to die for a life worth living, or because the terrorists themselves came to realize that free men cannot be frightened by threats, and that aggression would meet its own response. And it is in the light of that history that every nation today should know, be he friend or foe, that the United States has both the will and the weapons to join free men in standing up to their responsibilities."

Communist or terrorist threat, the Sky Shield exercises had made a mere dent in airline operations. The public’s support of the military was unwavering, and the advance notice of the exercises allowed plenty of time to make alternate travel plans.

Sky Shield came at a time of record airline growth and revenue for passenger jet travel, which was in its infancy, but record low profits, because of fare wars. Airlines merged, cut costs, and called for a five percent fare hike. Eastern Airlines president Malcolm MacIntyre spoke for the industry in September 1961, telling a New York press luncheon that "the bottom of the business had dropped out" and calling 1961 "a very bad year, the biggest red-ink year barring none."

The entire U.S. civil fleet would not be grounded again until September 11, 2001—and then for days instead of hours, and with devastating financial and pyschological costs.

A researcher at Air & Space magazine, Roger A. Mola is working on a documentary film, Skyshield: This is Only a Test, based on this article, which appeared in our February/March 2002 issue. Mola can be reached at operationskyshield@yahoo.com. 

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