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The most well known distress signal is the Morse code group SOS, which is sent as di' di' dit dah dah dah di' di' dit, ...---.... This is often sent with no spacing between the S and the Os.
Another distress signal is the code word Mayday. The keyword MAYDAY should only be used from a vessel or aircraft in immediate danger of sinking or crashing.
One common distress signal is any unusual action repeated in groups of three. This could be three puffs of smoke (by covering and uncovering a campfire), three gunshots, and so on.
Other distress signals are primarily for use in rural or isolated areas, or in the wilderness. Survival training includes ground to air signals that can be used to signal passing aircraft with flares, mirrors or marks made on the ground or snow. These signals should not be used except in an actual emergency and should be destroyed when the person signaling is rescued. Pilots will sometimes take extreme risks to locate and report what they believe to be an emergency signal from the ground.
Emergency beacons aboard aircraft and surface ships may be activated upon a crash or contact with water (as in a sinking). Modern beacons transmit a radio frequency signal at 406 MHz, while older beacons transmit signals at 121.5 MHz or 243 MHz for civil and military purposes, respectively. These beacons can be detected by satellites, which relay the signal to nearby rescue services. The use of satellites makes it possible for signals sent from remote locations to be picked up.
RescueRescue refers to operations that usually involve the saving of life, or prevention of additional injury. Rescue operations often involve technical work, such as use of the " Jaws of Life" or similar hydraulic cutting and spreading tools to remove individu