It all started with CONELRAD (Control of Electromagnetic Radiation) back in 1951, just in time for the Cold War (Doesn’t CONELRAD sound like a Cold War acronym?) Actually, that’s not entirely true. Radio stations and networks could break into their regularly scheduled programming in case of an emergency before 1951. In fact, they did on that tragic day in December, 1941. But it was all ad hoc until CONELRAD was born.
In the event of an emergency (especially a nuclear one) TV and FM radio would stop broadcasting. AM stations would then transmit warnings and updates for several minutes, before going off the air. Then, another station would take over on the same frequency, and so on in a round robin chain. Why? To confuse enemy aircraft, of course! (Ever wonder why many old radios have a triangle-in-circle mark on certain AM frequencies? That’s because they were required to by law between 1953 and 1963.)
National Emergency Alarm Repeater
CONELRAD was not very successful, prone to false alarms from lightening storms, and such. So in 1956, the government released the NEAR (National Emergency Alarm Repeater) program. This was a very small box that you’d plug into an outlet. In case of an emergency, a special signal would be sent over the power grid. According to this piece over on PBS’ Web site: “For unspecified reasons, the program went defunct and the devices were destroyed by their respective manufacturers.”
"If This Had Been an Actual Emergency..."
Ah, the one most of us grew up hearing about, the EBS. The Emergency Broadcast System replaced CONELRAD in 1963 and used often (as in more than 20K times). Thankfully, it was never used for what it was really intended for (war or the threat of war), but rather severe weather hazards.
There was, however, a major false alarm in 1971, that, in different times, might have brought us to the brink of war. Yes, it seems the system was inadvertently activated by a teletype operator who accidentally "played the wrong tape" during a test of the system. The codeword "hatefulness" was sent through the entire system, ordering stations to cease regular programming and broadcast the alert of a national emergency.
The outcome? Many stations never even received the alert. More interesting and, er, alarming? The majority of those that did ignored it! The net outcome? Numerous investigations were launched.
Emergency Alert System
In 1997, the EBS was replaced by the EAS. Though it’s never been used, thankfully, in theory, the President should be able to speak to all citizens through every possible medium (including things like Direct TV) within 10 minutes of an emergency. State or local authorities, the National Weather Service, or even the broadcaster also have access to this system for lesser emergencies.
The whole system works off a series of digital decoders and encoders, which the FCC oversees. There are more than 80 different categories of emergency warnings, including your standard tornado warnings but also things like the AMBER Alert System for child abduction emergencies.
Interestingly, according to WIKI, “‘... the EAS was not activated nationally or regionally in New York or Washington during the [9/11] terrorist attacks on the nation.’ Richard Rudman, then chairman of the EAS National Advisory Committee explained that near immediate coverage in the national media meant that the media itself provided the warning or alert of what had happened and what might happen as quickly as the information could be distributed. ‘Some events really do serve as their own alerts and warnings. With the immediate live media coverage, the need for an EAS warning was lessened.’”