Operation Sky Shield
Operation Skyshield was a series of three large-scale military exercises conducted in the United States in 1960, 1961, and 1962 to test the North American Aerospace Defense Command (NORAD) defenses against Soviet air attack. The tests were intended to ensure that any attacks over the Canadian border or coastlines would be detected and subsequently stopped. The results of the tests were classified until 1997 fearing they could be used by the Soviet Union in order to more effectively engage the U.S. in the event of World War III.
In these exercises, all U.S. civil air traffic was grounded (sometimes up to 12 hours). They involved 6,000 sorties flown by air forces from the US, UK and Canada simulating Soviet fighter / bomber attacks against New York, Chicago, and Washington. This made it the largest military aviation exercise ever held.
During the September 11 attacks in 2001 these exercises were not remembered by many reporters, who reported that a similar – but unplanned – evacuation of U.S. airspace during that incident was the first ever.
Operations
Sky Shield I (1960) included an "attack" by 8 Royal Air Force (RAF) V Bombers. The first "casualty" of the exercise was an RAF Vulcan which was intercepted by an F-101 Voodoo above Goose Bay, Labrador. Despite this, the Vulcans achieved unprecedented survivability with 7 of the 8 British bombers managing to reach their targets and return to Stephenville, Newfoundland unscathed, largely due to the advanced Electronic Counter Measures systems on these bombers and their unique maneuverability (for strategic bombers), which allowed them to fly tree top (below 100 feet) missions more accustomed to a fighter-bomber.
During Skyshield II (1961), the Vulcans simulated Russian heavy bombers operating at the highest tier (56,000 ft) above the United States Air Force (USAF) B-52s at 35-42,000 ft and the lower level B-47s. During this exercise, 8 casualties occurred, all from the same B-52 crew. On October 15 1961 a search triangle 600 miles from New York was set up looking for the missing crew. A U.S. Coast Guard (USCG) cutter reported seeing an orange flare at 12:15am on October 17, but the 8 crew members were eventually lost at sea.
Sky Shield III, held in September 1962, was North America's first test of procedures for clearing national civilian air traffic at short notice, such as would be done in the event of a Soviet attack. Hundreds of USAF trainers were used to simulate normal civil traffic levels and routes.