A faster, more lethal spy plane[ Wed, 06 Nov 2013 16:01:37 EST ]For a big chunk of the Cold War, the U.S. Air Force turned to the SR-71 Blackbird for many of its most important spy missions. The jet-black jet could fly at more than three times the speed of sound at altitudes of 85,000 feet, faster and higher than anything adversaries had to counter it.