Emergency override system
The Local Access Alert (also known as Local Access System or Emergency Override System) is a system designed to warn radio stations, television stations, cable television broadcast feeds or satellite signals of impending dangers such as severe weather and other civil emergencies. With a gradual transition from analog cable to digital cable, the Local Access Alert has been phased out and largely replaced with the Emergency Alert System in the United States.[1]
Type
Some broadcast television stations and cable systems
Mostly areas that have not upgraded to the Emergency Alert System
Unknown
Unknown
Emergency Bulletins
Purpose[edit]
Police or emergency management let cable viewers in local and surrounding areas know of an impending emergency and instruct them to shelter or evacuate. Alerts are chiefly for weather warnings for severe weather such as tornadoes, flash floods, earthquakes, winter storms, and hurricanes. Alerts may also pertain to Amber alerts, traffic closures, 911 outages, forest fires, dam failures, train derailments, and road conditions.
Activation procedure[edit]
The Local Access Alert is initiated by local law enforcement or emergency management staff, much like the antiquated Emergency Broadcast System, by dialing a number and entering a PIN through a telephone to take control of the cable of an area in the path of danger. Cable subscribers in that area have every television channel interrupted by audio and often a given screen. The distinct attention signal played can be Morse code, a siren, DTMF tones, steady single (or dual) tones, or multiple hi-lo beeps. The screen shown can be black, white, colored depending on warning, a slide or static. More modern alerts use a black screen with the words "Local Access Alert" in all capital letters with a message stating that "a local authority has initiated a direct community access"; the text was generated using the Trilithic EASyPLUS character generator (the same one used for the Emergency Alert System).
System tests[edit]
Tests of the Local Access Alert occur once weekly at randomly selected times, as well as scheduled monthly tests and yearly tornado drills. These alerts resemble the format used for activation of the Emergency Broadcast System and the Emergency Alert System.
Limitations[edit]
A limitation of the Local Access Alert system is that operators have to dial out to end transmission. Simply hanging up the phone connected to the system after an emergency broadcast does not work, and viewers may hear other phone noises – such as off-hook tones or dial tones – before cable programming resumes.
The newer Emergency Alert System employs Specific Area Message Encoding 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.