Emergency Alert System

Emergency Alert System

The Emergency Alert System logo as of December 3, 2007
Type	Emergency warning system
Country	United States
TV stations	All broadcast television stations and cable systems
Radio stations	77 designated Primary Entry Point (PEP) stations. All commercial radio stations
Broadcast area	Varies; nationwide for national activation, limited to 31 counties (and equivalents) or states at a time for regional activation
Launch date	January 1, 1997; 27 years ago (January 1, 1997)
Replaced	Emergency Broadcast System, Local Access Alert

The Emergency Alert System (EAS) is a national warning system in the United States designed to allow authorized officials to broadcast emergency alerts and warning messages to the public via cable, satellite and broadcast television and both AM, FM and satellite radio. Informally, Emergency Alert System is sometimes conflated with its mobile phone counterpart Wireless Emergency Alerts (WEA), a different but related system. However, both the EAS and WEA, among other systems, are coordinated under the Integrated Public Alert and Warning System (IPAWS). The EAS, and more broadly IPAWS, allows federal, state, and local authorities to efficiently broadcast emergency alert and warning messages across multiple channels.^[1] The EAS became operational on January 1, 1997, after being approved by the Federal Communications Commission (FCC) in November 1994,^[2] replacing the Emergency Broadcast System (EBS), and largely supplanted Local Access Alert systems, though Local Access Alert systems are still used from time to time. Its main improvement over the EBS, and perhaps its most distinctive feature, is its application of a digitally encoded audio signal known as Specific Area Message Encoding (SAME), which is responsible for the characteristic "screeching" or "chirping" sounds at the start and end of each message. The first signal is the "header" which encodes, among other information, the alert type and locations, or the specific area that should receive the message. The last short burst marks the end-of-message. These signals are read by specialized encoder-decoder equipment. This design allows for automated station-to-station relay of alerts to only the area the alert was intended for.

Like the Emergency Broadcast System, the system is primarily designed to allow the President of the United States to address the country via all radio and television stations in the event of a national emergency. Despite this, neither the system nor its predecessors have been used in this manner. The ubiquity of news coverage in these situations, such as during the September 11 attacks, has been credited to making usage of the system unnecessary or redundant.^[3] In practice, it is used at a regional scale to distribute information regarding imminent threats to public safety, such as severe weather situations (including flash floods and tornadoes), AMBER Alerts, and other civil emergencies.

It is jointly coordinated by the Federal Emergency Management Agency (FEMA), the Federal Communications Commission (FCC) and the National Oceanic and Atmospheric Administration (NOAA). The EAS regulations and standards are governed by the Public Safety and Homeland Security Bureau of the FCC. All broadcast television, broadcast and satellite radio stations, as well as multichannel video programming distributors (MVPDs), are required to participate in the system.