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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: * Alert or notification of a distress in progress * Position or location (or localization or pinpointing) of the party in distress. 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. == Maritime distress signals == Distress signals at sea are defined in the International Regulations for Preventing Collisions at Sea and in the International Code of Signals. Mayday signals must only be used where there is grave and imminent danger to life. Otherwise, urgent signals such as pan-pan can be sent. Most jurisdictions have large penalties for false, unwarranted or prank distress signals. Distress can be indicated by any of the following officially sanctioned methods: * Transmitting a spoken voice Mayday message by radio over very high frequency (shorter range VHF) channel 16 (156.8 MHz) and/or high frequency (longer range HF) on 2182 kHz * Transmitting a digital distress signal by activating (or pressing) the distress button (or key) on a marine radio equipped with Digital Selective Calling (DSC) over the VHF (channel 70) and/or HF frequency bands. * Transmitting a digital distress signal by activating (or pressing) the distress button (or key) on an Inmarsat-C satellite internet device * Sending the Morse code group SOS by light flashes or sounds * Burning a red flare (either hand-held or aerial parachute flare) * Lighting a non-pyrotechnic visual distress signal device〔(【引用サイトリンク】website=Sirius Signal )〕 * Emitting orange smoke from a canister * Showing flames on the vessel (as from a burning tar barrel, oil barrel, etc.) * Raising and lowering slowly and repeatedly both arms outstretched to each side * Making a continuous sound with any fog-signalling apparatus * Firing a gun or other explosive signal at intervals of about a minute * Flying the international maritime signal flags NC * Displaying a visual signal consisting of a square flag having above or below it a ball or anything resembling a ball (round or circular in appearance) * Launching distress rockets In addition, a distress can be signaled using automated radio signals such as a Search and Rescue Transponder (SART) which responds to 9 GHz radar signal, or an Emergency Position-Indicating Radio Beacon (EPIRB) which operates in the 406 MHz radio frequency. EPIRB signals are received and processed by a constellation of satellites known as COSPAS-SARSAT. Older EPIRBs which use 121.5 MHz are obsolete. Many regulators require vessels which proceed offshore to carry an EPIRB. Many EPIRBs have an in-built Global Positioning System receiver. When activated these EPIRBs rapidly report the latitude and longitude of the emergency accurate to within 120m. The position of non-GPS EPIRBs is determined by the orbiting satellites, this can take ninety minutes to five hours after activation and is accurate to within 5 km. Marine safety authorities recommend the use of GPS-equipped EPIRBs.〔(【引用サイトリンク】url=http://beacons.amsa.gov.au/gps.html )〕 A miniaturised EPIRB capable of being carried in crew members' clothing is called a Personal Locator Beacon (PLB). Regulators do not view them as a substitute for a vessel's EPIRB. In situations with a high risk of "man overboard", such as open ocean yacht racing, PLBs may be required by the event's organisers. PLBs are also often carried during risky outdoor activities upon land. EPIRBs and PLBs have a unique identification number (UIN or "HexID"). A purchaser should register their EPIRB or PLB with the national search and rescue authority; this is free in most jurisdictions. EPIRB registration allows the authority to alert searchers of the vessel's name, label, type, size and paintwork; to promptly notify next-of-kin; and to quickly resolve inadvertent activations. A DSC radio distress signal can include the position if the lat/long are manually keyed into the radio or if a GPS-derived position is passed electronically directly into the radio. A Mayday message consists of the word "mayday" spoken three times in succession, which is the distress signal, followed by the distress message, which should include: * Name of the vessel or ship in distress * Her position (actual, last known or estimated expressed in lat./long. or in distance/bearing from a specific location) * Nature of the vessel distress condition or situation (e.g. on fire, sinking, aground, taking on water, adrift in hazardous waters) * Number of persons at risk or to be rescued; grave injuries * Type of assistance needed or being sought * Any other details to facilitate resolution of the emergency such as actions being taken (e.g. abandoning ship, pumping flood water), estimated available time remaining afloat In North America, marine search and rescue agencies in Canada and the United States also recognize certain other distress signals: * Sea marker dye * White high intensity strobe light flashing at 60 times per minute A floating man-overboard pole or dan buoy can be used to indicate that a person is in distress in the water and is ordinarily equipped with a yellow and red flag (international code of signals flag "O") and a flashing lamp or strobe light. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「distress signal」の詳細全文を読む スポンサード リンク
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