At any USAR operation, there needs to be a set of standard, internationally accepted signals that can be used to quickly communicate important messages.

Prior to committing personnel onto a rubble pile, ensure that you:

* Reinforce and follow the REPEAT acronym
* Ensure correct PPC/PPE is worn
* A full dynamic risk assessment is conducted, identifying risks and hazards
* Brief crews on operational and safety aspects of the operation, including the signals below

The most common device used is a hand-held air horn, carried by some USAR operators. Alternatively a vehicle horn or siren can be used.

3 short blasts	Evacuate the area immediately All rescuers need to assemble at the predetermined assembly point, regardless of the operation that they are performing. This may occur if there is a major aftershock or a secondary explosive device is found.
1 long blast	All quiet All rescuers on site need to reduce noise so that important operations can commence This may occur if rescuers are trying to locate a casualty or are having difficulty communicating with a trapped person.
1 long and 1 short blast	Resume operations This is sounded when rescuers can resume making noise. This may occur after a line and hail search has finished.