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Public Warning System

The Public Warning System (PWS) is a network of sirens that the SCDF has placed at strategic points throughout the island. The purpose of this system is to warn the public of imminent threats that could endanger lives and property.

The Public Warning System (PWS) Various Signals & Meanings


The Public Warning System will be used to warn of attacks from the air, land or sea, as well as natural and other man-made disasters. The table below shows what the various signals mean. It would be a good idea to memorise them.



"Alarm" Signal







"All Clear" Signal







"Important Message" Signal

How It Sounds*

Click for audio   (wav,307.09 KB)
Click for audio   (wav,331.59 KB)
Click for audio   (wav,307.08 KB)



This is sounded when an air raid or shelling is imminent.






This is sounded when the threat is over.






This is sounded to alert the population to an important broadcast on the radio.

What It Means


Move to a shelter immediately.






You can leave the shelter.







Tune in immediately to any local FM radio station.


*Click on image to hear the signal

Find out more information on Civil Defence Shelter


NOTE: To hear the audio recording of the various Public Warning Signals, click "How it Sounds" in table above. To find out more about the system, you may call the SCDF General Enquiries / Customer Service Centre at 1800-286-5555.


Contact us for more public education materials on the Public Warning System.

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Last updated on 25th Oct 2017