Warning system
File:TWS_295_Sirens,_Saudi_Arabia_Warning_System.jpg
File:Picswiss BL-56-08.jpg for civil protection throughout Switzerland. They are tested once a year, on the first Wednesday in February.[https://www.bevoelkerungsschutz.admin.ch/internet/bs/en/home/themen/alarmierung/sirenentest.html Testing sirens], Swiss Federal Office for Civil Protection (page visited on 7 September 2013). {{Audio|BABS - Allgemeiner Alarm.ogg|Sound sample}}]]
Image:Laser Warning Light and Sign.jpg exposure]]
A 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 mitigate or avoid it.{{how|date=June 2024}}{{citation needed|date=June 2024}}
Warnings cannot be effective unless people react to them. People are more likely to ignore a system that regularly produces false warnings (the cry-wolf effect), but reducing the number of false warnings generally also increases the risk of not giving a warning when it is needed.{{Cite journal| doi = 10.1016/j.ress.2015.05.003| issn = 0951-8320| volume = 142| pages = 192–202| last1 = Sättele| first1 = Martina| last2 = Bründl| first2 = Michael| last3 = Straub| first3 = Daniel| title = Reliability and effectiveness of early warning systems for natural hazards: Concept and application to debris flow warning| journal = Reliability Engineering & System Safety| access-date = 2018-02-07| date = October 2015| url = https://www.era.bgu.tum.de/fileadmin/w00bkd/www/Papers/2013_Saettele_et_al_Reliability_EWS.pdf| doi-access = free| archive-date = 2018-02-07| archive-url = https://web.archive.org/web/20180207122945/http://www.era.bgu.tum.de/fileadmin/w00bkd/www/Papers/2013_Saettele_et_al_Reliability_EWS.pdf| url-status = dead}} Some warnings are non-specific: for instance, the probability of an earthquake of a certain magnitude in a certain area over the next decade. Such warnings cannot be used to guide short-term precautions such as evacuation. Opportunities to take long-term precautions, such as better building codes and disaster preparedness, may be ignored.{{Cite web|url=https://www.theguardian.com/science/blog/2012/may/30/attempts-predict-earthquakes-harm-good|title = Attempts to predict earthquakes may do more harm than good | Professor David Petley|website = TheGuardian.com|date = 30 May 2012}}{{better citation needed|date=February 2018}}
File:Sirena electronica TWS 295 sirena alerta temprana para tsunami sismos inundaciones.jpg
Biological warning systems
- Aposematism (e.g. warning coloration)
- Climate canary
- Fear
- Miner's canary
- Pain
Man-made warning systems
=Civilian warning systems=
Image:Wheelock-as.jpg that warns people if a building is on fire]]
- Alberta Emergency Alert
- Alberta Emergency Public Warning System (replaced by Alberta Emergency Alert)[https://www.municipalaffairs.gov.ab.ca/ema_epws.htm] {{webarchive|url=https://web.archive.org/web/20061212051852/https://www.municipalaffairs.gov.ab.ca/ema_epws.htm|date=December 12, 2006}}
- Alert Ready (Canada)
- Automatic Warning System
- Child abduction alert system
- Dam safety system
- Earthquake warning system
- Emergency Alert System (EAS) (United States)
- Famine Early Warning Systems Network
- Federal Civil Defense Authority
- Fire alarm system
- Gale warning
- Ground proximity warning system
- Indian Ocean Tsunami Warning System
- International Early Warning Programme
- J-Alert (Japan)
- Lane departure warning system
- National Severe Weather Warning Service
- N.E.A.R. (National Emergency Alarm Repeater)
- North Warning System
- Standard Emergency Warning Signal (Australia)
- Traffic Collision Avoidance System
- Train Protection & Warning System
- Tsunami warning system
=Military warning systems=
Historical beacon-based systems:
- Byzantine beacon system in Asia Minor during the 9th century
Space-based missile early warning systems:
- Defense Support Program (United States, to be succeeded by the "Space-Based Infrared System")
- Space-Based Infrared System (SBIRS) (United States)
- Oko, also known as "SPRN" (Russia)
Airborne early warning systems:
- Airborne Early Warning and Control ("AWACS" for NATO, many countries have developed their own AEW&C systems)
Ground-based early warning radar systems:
- Ballistic Missile Early Warning System and PAVE PAWS (United States)
- Duga radar, also known as the "Russian Woodpecker" (Russia)
- Dnestr radar (1st generation Russian)
- Daryal radar (2nd generation Russian)
- Voronezh radar (3rd and current generation Russian)
- Chain Home (British, now defunct)
- Chain Home Low (British, now defunct)
- ROTOR (British, now defunct)
Optical sensors:
Emergency broadcasting:
- CONELRAD (United States, succeeded by the Emergency Broadcast System)
- Emergency Broadcast System (EBS) (United States, succeeded by the Emergency Alert System)