Personal locator beacons (PLBs) are devices that transmit your location via satellite to emergency services. They are used in life-threatening situations to signal that emergency help is required (e.g. group is lost, someone is injured or very unwell), and usually only activate when other forms of two-way communication such as a phone call cannot be made (e.g. group is out of mobile phone reception). PLBs are an important safety backup for groups traveling through areas with poor or no mobile phone reception, and have been proven time and time again to be a life-saving device for bushwalkers.