Important Message signal: Pulsating blasts sounded to alert the people of important messages broadcast by Singapore FM radio stations. This is the most used signal as to celebrate Total Defence and Civil Defence Days in Singapore, sounded at 12:05pm on these days. However, from Total Defence Day 2015 and 15 September 2018 onwards, this signal was sounded at 6:20 pm instead of 12:05pm in remembrance of the British's surrender of Singapore in World War II on 15 February 1942 at 6:20 pm.