On Saturday, February 20, 1971, a civilian teletype operator grabbed the wrong recording tape and instead of a test, inadvertently sent an Emergency Broadcast Alert to radio stations across the U.S. I've told stories about the Cold War and how seriously everyone took the Emergency Broadcast System (EBS). Activation of the system meant nuclear war to almost everyone who heard it.
Station managers, broadcasters and listeners across the country were thrown into a tizzy. David Skinner, the news director of WEVA in Emporia, Virginia recalled the experience for a reporter: “I thought I was going to have a heart attack trying to open that damned envelope [containing the code words that authenticate the message from Cheyenne Mountain]. I haven’t felt that way since John Kennedy was killed.”
Chuck Kelly of WWCM in Brazil, Indiana took his station off the air for twenty-two minutes and told a reporter, “I saw the authenticated message and thought, ‘My God! It’s December 7  all over again!’”
It took 40 minutes of panicky fumbling before the alert could be properly killed. The audio of the incident from WOWO radio in Fort Wayne,m Indiana, is available along with the story of what happened at CONELRAD Adjacent. Link -via Metafilter