Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications.
Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).
An emergency position-indicating radiobeacon (EPIRB) is a type of emergency locator beacon for commercial and recreational boats, a portable, battery-powered radio transmitter used in emergencies to locate boaters in distress and in need of immediate rescue. In the event of an emergency, such as a ship sinking or medical emergency onboard, the transmitter is activated and begins transmitting a continuous 406 MHz distress radio signal, which is used by search-and-rescue teams to quickly locate the emergency and render aid. The signal is detected by satellites operated by an international consortium of rescue services, COSPAS-SARSAT, which can detect emergency beacons anywhere on Earth transmitting on the distress frequency of 406 MHz. The satellites calculate the position or utilize the GPS coordinates of the beacon and quickly passes the information to the appropriate local first responder organization, which performs the search and rescue. As Search and Rescue approach the search areas, they use Direction Finding (DF) equipment to locate the beacon using the 121.5 MHz homing signal, or in newer EPIRBs, the AIS location signal. The basic purpose of this system is to help rescuers find survivors within the so-called "golden day" during which the majority of survivors can usually be saved. The feature distinguishing a modern EPIRB, often called GPIRB, from other types of emergency beacon is that it contains a GPS receiver and broadcasts its position, usually accurate within 100 m (330 ft), to facilitate location. Previous emergency beacons without a GPS can only be localized to within 2 km (1.2 mi) by the COSPAS satellites and relied heavily upon the 121.5 MHz homing signal to pin-point the beacons location as they arrived on scene.
A distress signal, also known as a distress call, is an internationally recognized means for obtaining help. Distress signals are communicated by transmitting radio signals, displaying a visually observable item or illumination, or making a sound audible from a distance.
Marine VHF radio is a worldwide system of two way radio transceivers on ships and watercraft used for bidirectional voice communication from ship-to-ship, ship-to-shore, and in certain circumstances ship-to-aircraft. It uses FM channels in the very high frequency (VHF) radio band in the frequency range between 156 and 174 MHz, inclusive, designated by the International Telecommunication Union as the VHF maritime mobile band. In some countries additional channels are used, such as the L and F channels for leisure and fishing vessels in the Nordic countries. Transmitter power is limited to 25 watts, giving them a range of about 100 kilometres.
The Global Maritime Distress and Safety System (GMDSS) is a worldwide system for automated emergency signal communication for ships at sea developed by the United Nations' International Maritime Organization (IMO) as part of the SOLAS Convention.
The radiotelephony message PAN-PAN is the international standard urgency signal that someone aboard a boat, ship, aircraft, or other vehicle uses to declare that they need help and that the situation is urgent, but for the time being, does not pose an immediate danger to anyone's life or to the vessel itself. This is referred to as a state of "urgency". This is distinct from a mayday call, which means that there is imminent danger to life or to the continued viability of the vessel itself. Radioing "pan-pan" informs potential rescuers that an urgent problem exists, whereas "mayday" calls on them to drop all other activities and immediately begin a rescue.
The International Cospas-Sarsat Programme is a satellite-aided search and rescue (SAR) initiative. It is organized as a treaty-based, nonprofit, intergovernmental, humanitarian cooperative of 45 nations and agencies. It is dedicated to detecting and locating emergency locator radio beacons activated by persons, aircraft or vessels in distress, and forwarding this alert information to authorities that can take action for rescue. Member countries support the distribution of distress alerts using a constellation of around 65 satellites orbiting the Earth which carry transponders and signal processors capable of locating an emergency beacon anywhere on Earth transmitting on the Cospas-Sarsat frequency of 406 MHz.
2182 kHz is a radio frequency designed exclusively for distress calls and related calling operations in the maritime service. It is equivalent to a wavelength of 137.4 metres.
In navigation, a radio beacon or radiobeacon is a kind of beacon, a device that marks a fixed location and allows direction-finding equipment to find relative bearing. But instead of employing visible light, radio beacons transmit electromagnetic radiation in the radio wave band. They are used for direction-finding systems on ships, aircraft and vehicles.
The Joint Rescue Coordination Centre Victoria (JRCC Victoria) is a rescue coordination centre operated by the 1 Canadian Air Division (Canadian Armed Forces) and staffed by personnel of the Royal Canadian Air Force (RCAF) and the Canadian Coast Guard (CCG).
An international distress frequency is a radio frequency that is designated for emergency communication by international agreement.
L-Tronics was a company based in Santa Barbara, California that specialized in the design and manufacture of direction finding (DF) equipment for search and rescue applications, used to locate signals originating from emergency locator beacons. These include Emergency Locator Transmitters (ELTs) used by aircraft, Emergency Position Indicator Radio Beacons (EPIRBs) used by marine vehicles, and Personal Locator Beacons (PLBs). One major operator of L-Tronics devices is the Civil Air Patrol.
ENOS stands for "Elektronisches Notruf- und Ortungssystem" – "Electronic Rescue and Location System" - a system developed in Germany for use by divers at sea. ENOS allows people in distress to signal their location when drifting on the ocean's surface so they can be quickly located and rescued. Although the system was especially developed for scuba diving it can also be used for other water sports like windsurfing, jet skiing, sailing and boating.
Survival radios are carried by pilots and search and rescue teams to facilitate rescue in an emergency. They are generally designed to transmit on international distress frequencies. Maritime systems have been standardized under the Global Maritime Distress Safety System. Civil and military organisation's utilized different frequencies to communicate and no infringement on either sector would take place. For emergencies involving civilian aircraft, the radio frequency used is VHF 121.5 MHz and for military aircraft incidents, the frequency used is UHF 243 MHz.
The Joint Rescue Coordination Centre Halifax is a rescue coordination centre operated by the Royal Canadian Air Force (RCAF) and the Canadian Coast Guard (CCG).
The Joint Rescue Coordination Centre Trenton is a rescue coordination centre operated by the Royal Canadian Air Force (RCAF) and the Canadian Coast Guard (CCG).
On 20 January 2014, a Britten-Norman Islander light aircraft belonging to the Superior School of Aviation in Romania operating Flight 111 crashed in the Apuseni Mountains at an altitude of approximately 1,400 metres (4,600 ft), near the village of Petreasa, between Alba and Cluj counties. The aircraft was piloted by two crew and was transporting a five-person medical team from Bucharest to Oradea. The pilot and a medical student died, while the copilot and four medical doctors were injured.
An emergency locator beacon is a radio beacon, a portable battery powered radio transmitter, used to locate airplanes, vessels, and persons in distress and in need of immediate rescue. Various types of emergency locator beacons are carried by aircraft, ships, vehicles, hikers and cross-country skiers. In case of an emergency, such as the aircraft crashing, the ship sinking, or a hiker becoming lost, the transmitter is deployed and begins to transmit a continuous radio signal, which is used by search and rescue teams to quickly find the emergency and render aid. The purpose of all emergency locator beacons is to help rescuers find survivors within the so-called "golden day", the first 24 hours following a traumatic event, during which the majority of survivors can usually be saved.
The Breitling Emergency is a luxury watch produced by Breitling SA. It contains a radio transmitter for civil aviation use, which broadcasts on the 121.5 MHz distress frequency and serves as a backup for ELT-type airborne beacons. For military users, the Emergency has a miniaturized transmitter operating on the 243.0 MHz military aviation emergency frequency. Under normal conditions—flat terrain or calm seas—the signal can be picked up at a range of up to 90 nautical miles (170 km) by search aircraft flying at 20,000 feet (6,100 m). Since February 2009, the Cospas-Sarsat Satellite System has not monitored the 121.5/243.0 MHz frequency; however, the signal transmitted by the Emergency was never strong enough to be picked up by satellite, and Breitling has announced that, as these frequencies will still be monitored by aviation, particularly during the localization phase of a rescue attempt, there are no plans to modify the signal's frequency.
