The Local Access Alert (also known as Local Access System or Emergency Override System) is a

warning system Warning system is any system of biological or technical nature deployed by an individual or group to inform of a future danger. Its purpose is to enable the deployer of the warning system to prepare for the danger and act accordingly to mitigat ...

designed to warn

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transm ...

television stations A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the eart ...

cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

broadcast feeds or satellite signals of impending dangers, such as

tornadoes A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, alth ...

flash flooding A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice or snow flowing o ...

and other civil emergencies. The system was largely replaced by the

Emergency Alert System 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, or broadcast television, and both ...

in the United States, although it still exists in some areas which have not yet been upgraded, and is still used from time to time in areas that have upgraded to the EAS. Local Access Alert Screencap

The Local Access Alert was used by local

law enforcement agencies A law enforcement agency (LEA) is any government agency responsible for the enforcement of the laws. Jurisdiction LEAs which have their ability to apply their powers restricted in some way are said to operate within a jurisdiction. LEAs ...

and

emergency management Emergency management or disaster management is the managerial function charged with creating the framework within which communities reduce vulnerability to hazards and cope with disasters. Emergency management, despite its name, does not actuall ...

staff, and it's much like the antiquated

Emergency Broadcast System The Emergency Broadcast System (EBS), sometimes called the Emergency Broadcasting System or the Emergency Action Notification System (EANS), was an emergency warning system used in the United States. It replaced the previous CONELRAD system an ...

. A public servant would dial up a number and PIN through a

phone A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into ele ...

to take control of a certain cable city or cluster in the path of danger. Once the number and PIN are entered, it switches all cable subscribers, regardless of what channel they're on, to a black screen or static and uses a distinct attention signal (in this case, a

morse code Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one ...

, a siren,

DTMF Dual-tone multi-frequency signaling (DTMF) is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed ...

tones, steady single (or dual) tones, or multiple hi-lo beeps). Police or emergency management then let viewers know of an impending disaster and instructs them to take shelter or evacuate. The more modern systems use a black screen with the words "Local Access Alert" in all capital letters, using Trilithic EASyPLUS as the text generator. The problem with the Local Access Alert system is that the operators would have to dial out to end transmission. Simply hanging up the phone connected to such system after an emergency broadcast would not work, and sometimes viewers would hear other phone noises (examples:

off-hook In telephony, on-hook and off-hook are two states of a communication circuit. On subscriber telephones the states are produced by placing the handset onto or off the hookswitch. Placing the circuit into the off-hook state is also called ''seizing th ...

and/or a

dial tone A dial tone is a telephony signal sent by a telephone exchange or private branch exchange (PBX) to a terminating device, such as a telephone, when an off-hook condition is detected. It indicates that the exchange is working and is ready to init ...

) before finally being switched back to normal cable operations. With a gradual transition from analog to

digital cable Digital cable is the distribution of cable television using digital data and video compression. The technology was first developed by General Instrument. By 2000, most cable companies offered digital features, eventually replacing their previo ...

, the Local Access Alert has been phased out and replaced by the

, which employs

Specific Area Message Encoding Specific Area Message Encoding (SAME) is a protocol used for framing and classification of broadcast emergency warning messages. It was developed by the United States National Weather Service for use on its NOAA Weather Radio (NWR) network, and w ...

technology to activate for potential disasters and deactivate to resume cable broadcasts, especially late at night when many public servants aren't available to break in.

References

{{Reflist United States civil defense Disaster preparedness in the United States Cable television Warning systems