A whistle is essential equipment for searchers to carry. It is also recommended that individuals carry a whistle on trips to remote areas. It is important to use a whistle that has a rating of 100 decibels or higher so that they can be heard from long distances when used. Some examples are whistles rated above 100 decibels are below.
Wear It Australia Safety Whistle
Generally recognised conventions for signalling with a whistles are:
One blast = Where are you?. Also used to respond to other whistle signals.
Two blasts = Come to me.
Three blasts = I need help! (distress, emergency)
Three of anything (whistle blasts, fires, rifle shots, piles of rocks, flashes of light, etc.) is universally recognized as a distress signal.
Each blast/signal should last about three seconds and should be repeated at regular intervals.