Distress signal

A distress signal or distress call is an internationally recognized means for obtaining help. Distress signals take the form of or are commonly made by using radio signals, displaying a visually detected item or illumination, or making an audible sound, from a distance.

A distress signal indicates that a person or group of people, ship, aircraft, or other vehicle is threatened by grave and imminent danger and requests immediate assistance. Use of distress signals in other circumstances may be against local or international law.

In order for distress signalling to be the most effective, two parameters must be communicated:

For example, a single aerial flare alerts observers to the existence of a vessel in distress somewhere in the general direction of the flare sighting on the horizon but extinguishes within one minute or less. A hand held flare burns for 3 minutes and can be used to localize or pinpoint more precisely the exact location or position of the party in trouble. An EPIRB both notifies or alerts authorities and at the same time provides position indication information.