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."