The SR-71 reconnaissance aircraft, used by the United States and introduced in January 1964 as a successor to
the U-2, is a two-seater twin jet designed to fly at 85,000 feet at a speed of Mach 3, making it the world’s fastest, highest-flying plane. In a record-breaking flight in September 1974, an SR-71 flew from New York to London in under two hours. Less than 30 SR-71s—eight of which were destroyed in accidents—had been built by Lockheed by the time it was withdrawn from operations in March 1990. It could map 100,000 square miles each hour, and the aircraft’s extraordinary characteristics, including its innovative design, astonishing speed, and low radar profile made it virtually invulnerable to attack from the ground.