text:
Aviation accidents and incidents

An aviation accident is an event during aircraft operation that causes serious injury, death, or destruction. An aviation incident is any operating event that compromises safety but does not progress to an actual accident. Preventing accidents and incidents is the main goal of aviation safety.

The first fatal aviation accident occurred on 10 May 1785, when a hot air balloon crashed in the town of Tullamore, Co. Offaly, Ireland. The town was seriously damaged from the resultant fire that burned down over 130 homes. The first involving a powered aircraft was the crash of a Wright Model A aircraft at Fort Myer, Virginia, in the United States on September 17, 1908, injuring its co-inventor and pilot, Orville Wright, and killing the passenger, Signal Corps lieutenant Thomas Selfridge.

Definitions
The Convention on International Civil Aviation Annex 13 formally defines an aviation accident as an occurrence associated with the operation of an aircraft, which takes place from the time any person boards the aircraft with the intention of flight until all such persons have disembarked, and in which (a) a person is fatally or seriously injured, (b) the aircraft sustains significant damage or structural failure, or (c) the aircraft goes missing or becomes completely inaccessible. Annex 13 defines an aviation incident as an occurrence, other than an accident, associated with the operation of an aircraft that affects or could affect the safety of operation.

A hull loss occurs if an aircraft is damaged beyond repair, is lost, or becomes completely inaccessible.

History
The first aircraft accident in which 200 or more people died occurred on March 3, 1974, when 346 died in the crash of Turkish Airlines Flight 981. , there have been a total of 33 aviation incidents in which 200 or more people have died.

The period from 1958 through 1968 saw tremendous growth in aviation. Improvements in aviation safety and accident investigation procedures were rapidly advancing. In 1963, the Civil Aeronautics Board, under the leadership of then Deputy Director Bobbie R. Allen, established the National Aircraft Accident Investigation School in Oklahoma City.

The ICAO's third accident investigation division meeting, held in Montreal, Canada in January 1965, laid the foundation for accident investigations throughout the world. The proposals were presented by the Director of the Civil Aeronautics Board Bureau of Safety, Bobbie R. Allen, who headed the U.S. delegation. The U.S. formally adopted the proposals at the White House on Dec 1, 1965.

The top 10 countries with the highest number of fatal civil airliner accidents from 1945 to 2021 are the United States, Russia, Canada, Brazil, Colombia, United Kingdom, France, Indonesia, Mexico, and India. The United Kingdom is noted to have the highest number of air crashes in Europe, with a total of 110 air crashes within the time period, and Indonesia is the highest in Asia at 104, followed by India at 95.

The most fatalities on board a single aircraft is the 520 fatalities of the 1985 Japan Airlines Flight 123 accident. The largest loss of life in a single aviation accident is the 583 fatalities of the 1977 Tenerife airport disaster, in which two Boeing 747s collided. The largest loss of life overall in a collective incident is the 2,996 fatalities in the coordinated terrorist destruction of airplanes and occupied buildings in the 2001 September 11 attacks, the first plane to be hijacked and crashed as part of the attack, American Airlines Flight 11, was alone responsible for an estimated 1,700 fatalities in total, making it the single deadliest aviation disaster in history.

September 11 attacks
2,996: The deadliest aviation-related disaster regarding fatalities both on board the aircraft and casualties on the ground, was the destruction of the World Trade Center in New York City on September 11, 2001. On that morning, four commercial jet airliners traveling on transcontinental flights from East Coast airports to California were hijacked after takeoff. The four hijacked aircraft were subsequently crashed in a series of four coordinated suicide attacks against major American landmarks by 19 Islamic terrorists affiliated with Al-Qaeda. American Airlines Flight 11 and United Airlines Flight 175, both regularly scheduled domestic transcontinental flights from Boston to Los Angeles, were hijacked by five men each, with the assigned pilot hijacker taking control of the flight, before being intentionally crashed into the North and South Towers of the World Trade Center, respectively, destroying both buildings in less than two hours. The World Trade Center crashes killed 2,753, as both planes were carrying a combined total of 157 occupants, the vast majority of fatalities were the occupants of the two towers and the emergency personnel responding to the disaster. In addition, 184 were killed by the impact of American Airlines Flight 77, which crashed into the Pentagon in Arlington County, Virginia, causing severe damage and partial destruction to the building's west side. The crash of United Airlines Flight 93 into a field in Somerset County, Pennsylvania, which occurred as passengers attempted to retake control of the aircraft from the hijackers, killed all 40 passengers and crew aboard the aircraft. This brought the total number of casualties of the September 11 attacks to 2,996 (including the 19 terrorist hijackers). As deliberate terrorist acts, the 9/11 crashes were not classified as accidents, but as mass-killing. The events were treated by the member nations of NATO as an act of war and terrorism. The war on terror was subsequently launched by NATO in response to the attacks, eventually leading to the death of Al-Qaeda leader Osama Bin Laden, who orchestrated the 9/11 attacks.

Tenerife disaster

583: The Tenerife airport disaster, which occurred on March 27, 1977, remains the accident with the highest number of airliner passenger fatalities. 583 people died when a KLM Boeing 747 attempted to take off and collided with a taxiing Pan Am 747 at Los Rodeos Airport on the Canary Island of Tenerife, Spain. All 234 passengers and 14 crew of the KLM aircraft died and 335 of the 396 passengers and crew of the Pan Am aircraft died. Pilot error was the primary cause, as the KLM captain began his takeoff run in the mistaken belief he had obtained air traffic control clearance. Other contributing factors were a terrorist incident at Gran Canaria Airport that had caused many flights to be diverted to Los Rodeos, a small airport not well equipped to handle aircraft of such size, and dense fog. The KLM flight crew could not see the Pan Am aircraft on the runway until immediately before the collision. The accident had a lasting influence on the industry, particularly in the area of communication. An increased emphasis was placed on using standardized phraseology in air traffic control (ATC) communication by both controllers and pilots alike. "Cockpit Resource Management" has also been incorporated into flight crew training. The captain is no longer considered infallible, and combined crew input is encouraged during aircraft operations.

Japan Airlines Flight 123
520: The crash of Japan Airlines Flight 123 on August 12, 1985, has the highest number of fatalities for any single-aircraft accident: 520 people died aboard a Boeing 747. The aircraft suffered an explosive decompression from an incorrectly repaired aft pressure bulkhead, which failed in mid-flight, destroying most of its vertical stabilizer and severing all of the hydraulic lines, making the 747 virtually uncontrollable. Pilots were able to keep the plane flying for 32 minutes after the mechanical failure before crashing into a mountain. All 15 crew members and 505 of the 509 passengers aboard died. Japanese military personnel inaccurately assumed, during a helicopter flyover of the impact site, that there were no survivors. Rescue operations were delayed until the following morning. Medical providers involved in rescue and analysis operations determined that several passengers likely survived the impact and probably would have survived the incident had rescue operations not been delayed. Four passengers survived the incident in its entirety, meaning that they were alive when discharged from the hospital.

Other crashes with death tolls of 200 or more
349: On November 12, 1996, Saudia Flight 763, operated by a Boeing 747, and Kazakhstan Airlines Flight 1907, operated by a Russian Ilyushin Il-76, collided mid-air over the town of Charkhi Dadri, near Delhi, India. The collision was mainly the result of the Kazakh pilot flying lower than the assigned clearance altitude. All 349 occupants on-board the two aircraft died. It remains the world's deadliest mid-air collision and without survivors. The Ramesh Chandra Lahoti Commission, empowered to study the causes, recommended the creation of the "semi-circular rule", to prevent aircraft from flying in opposite directions at the same altitude. The Civil Aviation Authorities in India made it mandatory for all aircraft flying in and out of India to be equipped with a Traffic Collision Avoidance System (TCAS), setting a worldwide precedent for mandatory use of TCAS.

346: On March 3, 1974, Turkish Airlines Flight 981, a McDonnell Douglas DC-10, crashed in a forest northeast of Paris, France. The London-bound aircraft crashed shortly after taking off from Orly airport; all 346 people aboard died. It was later determined that the cargo door detached, which caused an explosive decompression; this caused the floor just above to collapse. The collapsed floor severed the control cables, which left the pilots without control of the elevators, the rudder and No. 2 engine. The aircraft entered a steep dive and crashed. It was the deadliest plane crash of all time until the Tenerife disaster in 1977. However, it is currently the deadliest single-aircraft crash with no survivors. This accident was also the deadliest single-aircraft crash that did not involve a Boeing 747.

329: On June 23, 1985, Air India Flight 182, a Boeing 747-237B en route from Toronto and Montreal to London and Delhi, crashed off the southwest coast of Ireland when a bomb exploded in the cargo hold. All 307 passengers and 22 crew members died. One passenger had checked in as "M. Singh". Singh did not board the flight. However his suitcase, containing the bomb, was loaded onto the aircraft. "M. Singh" was never identified or captured. It was later determined Sikh extremists were behind the bombing as a retaliation for the Indian government's attack on the Golden Temple in the city of Amritsar, spiritually the most significant shrine in Sikhism. This was, at the time, the deadliest terrorist attack involving an airplane.

301: On August 19, 1980, Saudi Arabian Airlines Flight 163, a Lockheed L-1011, became the world's deadliest aviation accident that did not involve a crash. The crew performed an emergency landing at Riyadh after a fire broke out in an aft baggage compartment. The fire burned through the ceiling of the compartment and into the passenger cabin. While the crew managed to land the aircraft safely, the captain did not stop immediately and order an evacuation. He taxied off the runway instead, by which time everyone in the cabin had become unconscious due to fumes and were unable to open any doors or evacuate. All 301 passengers and crew aboard died of suffocation before rescue ground crews could open any door, after which the aircraft burst into flames and was consumed by fire.

298: On July 17, 2014, Malaysia Airlines Flight 17, a Boeing 777-200ER, flying from Amsterdam to Kuala Lumpur, was shot down in an area of Eastern Ukraine near the Ukraine/Russian border during the war in Donbas. There were 298 people on board: 283 passengers and 15 crew members, all of whom died. The crew were all Malaysians, while the passengers were of various nationalities, most from the Netherlands. Several Ukrainian Air Force (UAF) aircraft had been shot down over the rebel-controlled territory before the MH17 incident. Immediately after the crash, a post appeared on the VKontakte social media profile attributed to Igor Girkin, leader of the Donbas separatist militia, claiming responsibility for shooting down a Ukrainian An-26 military transport near Torez. The post was removed later the same day, and the separatists then denied shooting down any aircraft.

290: On July 3, 1988, Iran Air Flight 655, an Iranian civilian Airbus A300-200 airliner, was shot down by two surface-to-air missiles from the U.S. Navy guided missile cruiser USS Vincennes over the Strait of Hormuz. All 290 passengers and crew aboard the aircraft died. The downing was caused by a series of events that led the USS Vincennes crew to believe that the airliner was an Iranian Air Force F-14.

275: On February 19, 2003, an Iranian military Ilyushin Il-76 crashed in mountainous terrain near Kerman in Iran. The official report says bad weather brought the aircraft down; high winds and fog were present at the time of the crash.

273: On May 25, 1979, American Airlines Flight 191, a McDonnell Douglas DC-10-10, crashed shortly after lifting off the runway at Chicago O'Hare Airport after the number one (left) engine and pylon separated from the wing. This broke hydraulic lines, causing leading edge lift devices to retract on that side of the aircraft and resulted in asymmetrical lift and loss of control. The accident was attributed to improper maintenance procedures. The crash resulted in the deaths of all 271 passengers and crew on board, as well as two people on the ground. It remains the deadliest commercial aircraft accident in United States history, and was also the country's deadliest aviation disaster until the September 11 attacks in 2001.

270: On December 21, 1988, Pan Am Flight 103, a Boeing 747-121 bound for New York–JFK from London–Heathrow with continued service to Detroit, was destroyed by a terrorist bomb over the town of Lockerbie, Scotland. All 259 occupants and 11 people on the ground (all residents of Sherwood Crescent, Lockerbie), died, making it the worst terrorist attack involving an aircraft in the UK and the deadliest terrorist attack on British soil. Following the crash, the Federal Aviation Administration imposed new security measures on American airlines flying out of 103 airports in Western Europe and the Middle East.

269: On September 1, 1983, a Soviet interceptor Sukhoi Su-15 shot down Korean Air Lines Flight 007, a Boeing 747-230B, bound for Gimpo International Airport in Seoul, South Korea, after it flew into Soviet airspace; all 269 occupants on board died.

265: On November 12, 2001, American Airlines Flight 587, an Airbus A300, crashed in the Belle Harbor neighborhood of Queens, New York, just after departing John F. Kennedy International Airport bound for Las Américas International Airport, Santo Domingo. The first officer's overuse of the rudder in response to wake turbulence from a Japan Airlines 747 was cited as cause. All 260 people on board, as well as five people on the ground, died from the crash. It is the second-deadliest aviation accident on U.S. soil, after American Airlines Flight 191.

264: On April 26, 1994, China Airlines Flight 140 was completing a routine flight and approach at Nagoya Airport, Japan, when the Airbus A300B4-622R's First Officer inadvertently pressed the takeoff/go-around button, which raises the throttle position to the same as that for take offs and go-arounds. The action and the two pilots' reaction resulted in a crash that killed 264 (15 crew and 249 passengers) of the 271 people aboard.

261: On July 11, 1991, Nigeria Airways Flight 2120, a Douglas DC-8-61 aircraft operated by Nationair Canada, crashed in Jeddah, Saudi Arabia, after two tires ignited upon takeoff, leading to an in-flight fire. All 261 occupants were killed. It is the deadliest aviation accident involving a DC-8, the largest aviation disaster involving a Canadian-registered aircraft and the second-worst accident in Saudi Arabia (after Saudi Arabian Airlines Flight 163 - see above).

257: On April 11, 2018, an Algerian Air Force transport aircraft crashed shortly after take-off from Boufarik Airport, killing all 257 occupants on board the Ilyushin Il-76.

257: On November 28, 1979, Air New Zealand Flight 901, an Antarctic sightseeing flight, collided with Mount Erebus on Ross Island, Antarctica, killing all 257 occupants on board. The flight crew had not been informed that the computer coordinates for the flight path of the McDonnell Douglas DC-10-30 had been changed the night before, directing the flight directly into Mount Erebus rather than the usual path down McMurdo Sound.

256: On December 12, 1985, a Douglas DC-8, Arrow Air Flight 1285, carrying American military personnel on a charter flight home for Christmas, crashed in Newfoundland; all 256 occupants on board died. The Canadian Aviation Safety Board investigating the cause of the crash issued two different reports: the majority report cited ice on the wings as cause of the crash; the minority report suggests an explosion was the likely cause. This has been the deadliest aviation incident in Canadian history.

239: On March 8, 2014, a Boeing 777-200ER, Malaysia Airlines Flight 370, flying from Kuala Lumpur, Malaysia, to Beijing, China, lost contact with air traffic controllers over the South China Sea, deviated from its planned route, and was presumed lost in the southern Indian Ocean. It carried 12 Malaysian crew members and 227 passengers from 15 nations, who are all presumed dead. A multinational search effort, the most extensive and expensive in aviation history, has thus far failed to locate the aircraft, though debris from the aircraft has been recovered from beaches around the Indian Ocean. Numerous theories have been offered to explain the disappearance of the flight, but none have been confirmed.

234: On September 26, 1997, an Airbus A300B4-220, Garuda Indonesia Flight 152, which departed from Jakarta, Indonesia, and was preparing to land at Medan, North Sumatra, crashed into mountainous terrain, killing all 234 occupants on board. The causes included turning left instead of right as instructed by ATC and descending below the assigned altitude of 2,000 feet due to pilot error. It is the deadliest aviation disaster in Indonesia's history.

230: On July 17, 1996, a Boeing 747-131, TWA Flight 800, carrying 230 occupants, exploded and crashed into the Atlantic Ocean near East Moriches, New York, shortly after departing from John F. Kennedy International Airport on a flight to Paris and Rome. A lengthy investigation concluded that the probable cause of the accident was a short circuit in a fuel tank that contained an explosive mixture of fuel vapor and air. As a result, new requirements were developed to prevent future fuel tank explosions in aircraft.

229: On September 2, 1998, a McDonnell Douglas MD-11, Swissair Flight 111, carrying 215 passengers and 14 crew from New York City to Geneva, Switzerland, crashed into the Atlantic Ocean near Halifax, Nova Scotia, Canada, killing all 229 people aboard. After a lengthy investigation, an official report stated that flammable material used in the aircraft's structure, specifically the Personal TV Systems recently installed in the Business Class Cabin, allowed a fire to spread, resulting in a loss of control.

228: On June 1, 2009, an Airbus A330-203, Air France Flight 447, carrying 228 occupant, was en route from Rio de Janeiro, Brazil to Paris, France, when it crashed into the Atlantic Ocean. The aircraft's flight recorders were not recovered from the ocean floor until May 2011, and the final investigative report was released in July 2012. It determined that the disaster was likely due to the aircraft's pitot tubes being obstructed by ice crystals, causing the autopilot to disconnect. The crew reacted incorrectly, leading to an aerodynamic stall from which the jet did not recover.

228: On August 6, 1997, a Boeing 747-3B5, Korean Air Flight 801, crashed on approach to the international airport in the United States territory of Guam, killing 228 of the 254 people aboard. Contributing factors in the crash were fatigue and errors by the flight crew, inadequate flight crew training, and a modification of the airport's altitude warning system that prevented it from detecting aircraft below a minimum safe altitude.

227: On January 8, 1996, an Antonov An-32B aircraft with six crew members on board overshot the runway at N'Dolo Airport, Kinshasa, Democratic Republic of Congo, and plowed into a market place. Four on board survived but 225 people on the ground were killed and an estimated 500 were injured (estimated 253 seriously injured). It is the crash with the most non-passenger ground fatalities (not including 9/11). It is usually known as the 1996 Air Africa crash.

225: On May 25, 2002, a Boeing 747-209B, China Airlines Flight 611, bound for Hong Kong International Airport in Hong Kong, disintegrated in mid-air and crashed into the Taiwan Strait 20 minutes after takeoff from Chiang Kai-shek International Airport (now Taiwan Taoyuan International Airport) in Taiwan. It was determined that the crash, which killed all 206 passengers and 19 crew members aboard the plane, was caused by improper repairs to the aircraft 22 years earlier when the aircraft encountered a tailstrike.

224: On October 31, 2015, an Airbus A321-231, Metrojet Flight 9268, crashed in the Sinai Peninsula after departing Sharm el-Sheikh International Airport, Egypt, en route to Pulkovo Airport, Saint Petersburg, Russia. All 224 occupants on board were killed. A branch of the Islamic State of Iraq and the Levant claimed responsibility for bringing down the jet, and a Russian investigation concluded that a bomb was detonated inside the plane at a high altitude.

223: On May 26, 1991, a Boeing 767-3Z9ER, Lauda Air Flight 004, broke up in midair over a remote area of Thailand due to an uncommanded deployment of a thrust reverser on one of the plane's engines, killing all 223 occupants aboard. The flight, which originated at Kai Tak Airport, Hong Kong, and made a stopover at Don Mueang International Airport in Bangkok, Thailand, was en route to Vienna International Airport, Vienna, Austria, when the accident occurred.

217: On October 31, 1999, a Boeing 767-366ER, EgyptAir Flight 990, flying from Los Angeles International Airport, United States, to Cairo International Airport, Egypt, with a stop at John F. Kennedy International Airport, New York City, crashed into the Atlantic Ocean south of Nantucket Island, Massachusetts, killing all 217 occupants onboards. The National Transportation Safety Board determined that the probable cause of the crash was deliberate action by the relief first officer in response to his removal from international service within Egyptair, a finding disputed by Egyptian authorities who maintain another cause of the accident.

213: On January 1, 1978, a Boeing 747-237B, Air India Flight 855, crashed into the Arabian Sea just off the coast of Bombay, India, killing all 213 occupants on board. An investigation concluded that the captain became disoriented after the failure of one of the flight instruments in the cockpit, leading to "irrational control inputs" that caused the plane to crash.

202: On February 16, 1998, an Airbus A300B4-622R, China Airlines Flight 676, en route from Ngurah Rai Airport in Bali, Indonesia, to Chiang Kai-shek International Airport (now Taoyuan International Airport), Taiwan, crashed into a road and residential neighborhood in Taoyuan, Taiwan, killing 182 passengers, 14 crew, and six people on the ground. An investigation determined that when the control tower ordered the pilot to abort his landing and "go around" for a second attempt, the pilot, who had unintentionally released the plane's autopilot, did nothing to take control of the plane for 11 seconds as he apparently thought the autopilot would initiate the go around. As the aircraft approached the airport, the pilot executed a sudden steep ascent that produced a stall and crash. China Airlines was also criticized for "insufficient training".

200: On July 10, 1985, a Tupolev Tu-154B-2, Aeroflot Flight 7425, on a domestic Karshi–Ufa–Leningrad route, crashed near Uchkuduk, Uzbek SSR, Soviet Union, on the first leg of its route. All 200 occupants onboard were killed. An investigation concluded that the plane went down due to pilot error. The air crew used an inappropriately low airspeed, causing vibrations that they incorrectly interpreted as engine surges. As a result, they further reduced engine power, causing the aircraft to stall and crash.

Safety
In over one hundred years of implementation, aviation safety has improved considerably. In modern times, two major manufacturers still produce heavy passenger aircraft for the civilian market: Boeing in the United States, and the European company Airbus. Both of these manufacturers place a huge emphasis on the use of aviation safety equipment, now a billion-dollar industry in its own right; safety is a key selling point for these companies, as they recognize that a poor safety record in the aviation industry is a threat to corporate survival.

Some major safety devices now required in commercial aircraft are:
 * Evacuation slides, to aid rapid passenger exit from an aircraft in an emergency situation
 * Advanced avionics, incorporating computerized auto-recovery and alert systems
 * Turbine engines with improved durability and failure containment mechanisms
 * Landing gear that can be lowered even after loss of power and hydraulics

Measured on a passenger-distance calculation, air travel is the safest form of transportation available: Figures mentioned are the ones shared by the air industry when quoting air safety statistics. A typical statement, e.g., by the BBC: "UK airline operations are among the safest anywhere. When compared against all other modes of transport on a fatality per mile basis, air transport is the safest – six times safer than travelling by car and twice as safe as rail." When measured by fatalities per person transported, however, buses are the safest form of transportation. The number of air travel fatalities per person is surpassed only by bicycles and motorcycles. This statistic is used by the insurance industry when calculating insurance rates for air travel.

For every billion kilometers traveled, trains have a fatality rate that is 12 times higher than that of air travel, and the fatality rate for automobiles is 62 times greater than for air travel. By contrast, for every billion journeys taken, buses are the safest form of transportation; using this measure, air travel is three times more dangerous than car transportation, and almost 30 times more dangerous than travelling by bus.

A 2007 study by Popular Mechanics magazine found that passengers sitting at the back of an aeroplane are 40% more likely to survive a crash than those sitting at the front. The article quotes Boeing, the FAA, and a website on aircraft safety, all of which claim that there is no "safest" seat. The study examined 20 crashes, not taking into account the developments in safety after those accidents. However, a flight data recorder is usually mounted in the aircraft's empennage (tail section) where it is more likely to survive a severe crash.

Between 1983 and 2000, the survival rate for people in U.S. plane crashes was greater than 95 percent.

Global Aeronautical Distress and Safety System
In an effort to prevent incidents such as the disappearance of Malaysia Airlines Flight MH370, a new standard has been issued requiring all commercial aircraft to report their position every 15 minutes to air traffic controllers regardless of the country of origin. Introduced in 2016 by the ICAO, the regulation has no initial requirement for any new aircraft equipment to be fitted. The standard is part of a long-term plan, called the Global Aeronautical Distress and Safety System (GADSS), which will require new aircraft to be equipped with data broadcast systems that are in constant contact with air traffic controllers. The GADSS is similar to the Global Maritime Distress and Safety System (GMDSS) used for maritime safety.

Aviation Safety Reporting System
The Aviation Safety Reporting System (ASRS) collects voluntarily submitted aviation safety incident/situation reports from pilots, controllers and others. The ASRS uses reports to identify system deficiencies, issue alert messages, and produce two publications, CALLBACK, and ASRS Directline. The collected information is made available to the public, and is used by the FAA, NASA and other organizations working in research and flight safety.

Bureau of Aircraft Accidents Archives (B3A)
The Bureau of Aircraft Accidents Archives (B3A), formerly known as the Aircraft Crashes Record Office (ACRO), a non-government organization based in Geneva, Switzerland, compiles statistics on aviation accidents of aircraft capable of carrying more than six passengers, excluding helicopters, balloons, and combat aircraft. ACRO only considers crashes in which the aircraft has suffered such damage that it is removed from service, which will further reduce the statistics for incidents and fatalities compared to some other data. The total fatalities due to aviation accidents since 1970 is 83,772. The total number of incidents is 11,164.

According to ACRO, recent years have been considerably safer for aviation, with fewer than 170 incidents every year between 2009 and 2017, compared to as many as 226 as recently as 1998.

The annual fatalities figure is less than 1,000 for ten of the fourteen years between 2007 and 2020, the year 2017 experiencing the lowest number of fatalities, at 399, since the end of World War II.

2014 included the disappearance of flight MH370 over the Indian Ocean and the shootdown of flight MH17 as part of the war in Donbas. The total number of fatalities in 2014 was 869 more than in 2013.

Deaths and incidents per year according to ACRO and Bureau of Aircraft Accident Archives data, :

(Data have significantly changed since November 2015 after a major upgrade to the death rate and crash rate web pages. This may reflect a change between a static and dynamic web page, where data were made to be automatically updated based on the incidents in their archives.)

Annual Aviation Safety Review (EASA)
The European Aviation Safety Agency (EASA) is tasked by Article 15(4) of Regulation (EC) No 216/2008 of the European Parliament and of the Council of February 20, 2008, to provide an annual review of aviation safety.

The Annual Safety Review presents statistics on European and worldwide civil aviation safety. Statistics are grouped according to type of operation, for instance, commercial air transport, and aircraft category, such as aeroplanes, helicopters, gliders, etc. The Agency has access to accident and statistical information collected by the International Civil Aviation Organization (ICAO). States are required, according to ICAO Annex 13, on Aircraft Accident and Incident Investigation, to report to ICAO information, on accidents and serious incidents to aircraft with a maximum certificated take-off mass (MTOM) over 2250 kg. Therefore, most statistics in this review concern aircraft above this mass. In addition to the ICAO data, a request was made to the EASA Member States to obtain light aircraft accident data. Furthermore, data on the operation of aircraft for commercial air transport were obtained from both ICAO and the NLR Air Transport Safety Institute.

Investigation
Annex 13 of the Chicago Convention provides the international Standards And Recommended Practices that form the basis for air accident and incident investigations by signatory countries, as well as reporting and preventive measures. The International Civil Aviation Organization (ICAO) is specifically focused on preventing accidents, rather than determining liability.

Australia
In Australia, the Australian Transport Safety Bureau is the federal government body responsible for investigating transport-related accidents and incidents, covering air, sea, and rail travel. Formerly an agency of the Department of Infrastructure, Transport, Regional Development and Local Government, in 2010, in the interests of keeping its independence it became a stand-alone agency.

Brazil
In Brazil, the Aeronautical Accidents Investigation and Prevention Center (CENIPA) was established under the auspices of the Aeronautical Accident Investigation and Prevention Center, a Military Organization of the Brazilian Air Force (FAB). The organization is responsible for the activities of aircraft accident prevention, and investigation of civil and military aviation occurrences. Formed in 1971, and in accordance with international standards, CENIPA represented a new philosophy: investigations are conducted with the sole purpose of promoting the "prevention of aeronautical accidents".

Canada
In Canada, the Transportation Safety Board of Canada (TSB), is an independent agency responsible for the advancement of transportation safety through the investigation and reporting of accident and incident occurrences in all prevalent Canadian modes of transportation – marine, air, rail and pipeline.

China
In China, the Civil Aviation Administration of China (CAAC) is totally responsible for all air investigations and safety inside the country after the split from the formal CAAC Airlines.

Ethiopia
In Ethiopia, the Civil Aviation Accident Prevention and Investigation Bureau of the Ethiopian Civil Aviation Authority (ECAA), which is an agency of the Ministry of Transport and Communications, conducts aircraft accident investigations in Ethiopia or involving Ethiopian aircraft.

France
In France, the agency responsible for investigation of civilian air crashes is the Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA). Its purpose is to establish the circumstances and causes of the accident and to make recommendations for their future avoidance.

Germany
In Germany, the agency for investigating air crashes is the Federal Bureau of Aircraft Accidents Investigation (BFU). It is an agency of the Federal Ministry of Transport and Digital Infrastructure. The focus of the BFU is to improve safety by determining the causes of accidents and serious incidents and making safety recommendations to prevent recurrence.

Hong Kong
The Air Accident Investigation Authority (AAIA) is responsible for investigating civil aviation accidents in Hong Kong, as well as those in other territories involving a Hong Kong-registered aircraft. It is led by Darren Straker, Chief Inspector of Accidents, and headquartered at Hong Kong International Airport. AAIA was established in 2018 in response to an ICAO directive instructing that member states maintain air accident investigation authorities that are independent of civil aviation authorities and related entities. Prior to 2018, accident investigation duties were held by the Civil Aviation Department's Flight Standards & Airworthiness Division and Accident Investigation Division.

India
Until May 30, 2012, the Directorate General of Civil Aviation investigated incidents involving aircraft. Since then, the Aircraft Accident Investigation Bureau has taken over investigation responsibilities.

Indonesia
In Indonesia, the National Transportation Safety Committee (NTSC; Komite Nasional Keselamatan Transportasi, KNKT) is responsible for the investigation of incidents and accidents, including air accidents. Its aim is the improvement of transportation safety, not just aviation, in Indonesia.

Italy
Created in 1999 in Italy, the Agenzia Nazionale per la Sicurezza del Volo (ANSV), has two main tasks: conducting technical investigations for civil aviation aircraft accidents and incidents, while issuing safety recommendations as appropriate; and conducting studies and surveys aimed at increasing flight safety. The organization is also responsible for establishing and maintaining the "voluntary reporting system". Although not under the supervision of the Ministry of Infrastructure and Transport, the ANSV is a public authority under the oversight of the Presidency of the Council of Ministers of Italy.

Japan
The Japan Transport Safety Board investigates aviation accidents and incidents. The Aircraft Accident Investigation Commission investigated aviation accidents and incidents in Japan until October 1, 2001, when the Aircraft and Railway Accidents Investigation Commission (ARAIC) replaced it, and the ARAIC did this function until October 1, 2008, when it merged into the JTSB.

Malaysia
Established in 2016, the Air Accident Investigation Bureau (AAIB) Malaysia is the main investigation body for aircraft accident/incident. Separate from Civil Aviation Authority of Malaysia (CAAM) and Malaysian Aviation Commission (MAVCOM) that is the national aviation authority and commission that oversee aviation economy respectively. The AAIB operates from the ministry of transport headquarters in Putrajaya, and its black box laboratory situated in STRIDE, the ministry of defenses research institute. AAIB Malaysia is teamed by civilians and seconded Royal Malaysian Airforce senior officer and a group of pool investigators from Malaysia Institute of Aviation Technology

Mexico
In Mexico, the Directorate General of Civil Aviation (DGAC) investigates aviation accidents.

Netherlands
In the Netherlands, the Dutch Safety Board (Onderzoeksraad voor Veiligheid) is responsible for the investigation of incidents and accidents, including air accidents. Its aim is the improvement of safety in the Netherlands. Its main focus is on those situations in which civilians are dependent on the government, companies or organizations for their safety. The Board solely investigates when incidents or accidents occur and aims to draw lessons from the results of these investigations. The Safety Board is objective, impartial and independent in its judgment. The Board will always be critical towards all parties concerned.

New Zealand
In New Zealand, the Transport Accident Investigation Commission (TAIC) is responsible for the investigation of air accidents. "The Commission's purpose, as set out in its Act, is to determine the circumstances and causes of aviation, rail and maritime accidents, and incidents, with a view to avoiding similar occurrences in the future, rather than to ascribe blame to any person." The TAIC investigates with accordance with annex 13 of the ICAO and specific New Zealand legislation.

Poland
In Poland, State Commission on Aircraft Accidents Investigation (Polish: Państwowa Komisja Badania Wypadków Lotniczych, PKBWL) is responsible for investigating all civil aviation accidents and incidents occurring in the country. Headquartered in Warsaw, the commission is a division of the Ministry of Infrastructure. As of November 2022, the head of the PKBWL is Bogusław Trela.

Russia
In Russia, the Interstate Aviation Committee (IAC, MAK according to the original Russian name) is an executive body overseeing the use and management of civil aviation in the Commonwealth of Independent States. This organization investigates air accidents in the former USSR area under the umbrella of the Air Accident Investigation Commission of the Interstate Aviation Committee. There are active discussion to dismantling the committee, and in 2020, Armenia and Russia has signed on a joint agreement establishing the International Bureau for investigating aviation accidents and serious incidents (In Russian: Международное бюро по расследованию авиационных происшествий и серьезных инцидентов), designed to replace the committee and to act as upper body for investigation of aviation incidents and, subordinate to the Eurasian Union. The new body has been assigned duties to investigate serious accidents and incidents in accordance with the requirements of ICAO documents, ensuring independent investigation of accidents, cooperation and interaction between the parties in relation to investigating aircraft accidents, development and use of common rules and procedures for investigating aircraft accidents.

Taiwan
In Taiwan, the Taiwan Transportation Safety Board (TTSB) is the independent government agency that is responsible for major transportation accident investigations. TTSB's predecessor was ASC, which was established in 1998. TTSB is under the administration of the Executive Yuan and independent from Civil Aviation Administration. The TTSB consisted of five to seven board members, including a chairman and a vice chairman, appointed by the Premier. The managing director of TTSB manages the day-to-day function of the organization, including accident investigations.

United Kingdom

In the United Kingdom, the agency responsible for investigation of civilian air crashes is the Air Accidents Investigation Branch (AAIB) of the Department for Transport. Its purpose is to establish the circumstances and causes of the accident and to make recommendations for their future avoidance.

United States
United States civil aviation incidents are investigated by the National Transportation Safety Board (NTSB). NTSB officials piece together evidence from the crash site to determine likely cause, or causes. The NTSB also investigates overseas incidents involving US-registered aircraft, in collaboration with local investigative authorities, especially when significant loss of American lives occurs, or when the involved aircraft is American-built.

Retirement of flight numbers
Out of respect for the deceased and injured, it is common for an airline to cease using the flight number of a fatal crash. For example, following the shootdown of Malaysia Airlines Flight 17, the flight number was changed to MH19. Japan Airlines stopped using the flight number 350 after a fatal plane crash in Tokyo Bay. However, that is not always the case. For example, China Southern Airlines continued using the flight number 3456 even after a fatal crash in 1997. Same with Japan Airlines and Singapore Airlines. Who continued using the flight number 516 and 321 even after a collision in 2024 and a flight facing severe turbulence causing one death. TransAsia Airways retired the flight number 235 and changed it to 2353 after a plane crash in 2015 leaving 15 survivors.

title: Aviation accidents and incidents


text:
Talk:Ani Hyuntikwalaski

untitled
Old, disturbing text:
 * One of the greatest Original Inhabitants of Turtle Island, the Ani Hyuntikwalaski or the "People of the Land of Lightning" that the European invaders attempted to destroy by the 'doctrine of discovery'.
 * Thomas Jefferson: "...if ever we are constrained to lift the hatchet against any tribe we will never lay it down till that tribe is exterminated,..." Treaty of 1846: "...the Indians become extinct..."
 * Their original name is the Chickamaugans. At the time of white contact three distinct groups of Cherokee were known. The Middle, Lower and Overhill. The Overhill Cherokees were different in many ways from the others.
 * Their tradition tells of following a bending stick to the land of gandga gidi or Kentucky and the areas of the Cumberland and Tennessee River Valley.
 * The 'Proud' priesthood people were the Lower Cherokee who had been driven into exile in the mountains of North Carolina after their 'Priests' offended the creator when they misused their power such that it touched off a centuries long war: 'Mound Builders' war.
 * When the whites came they found ready participants for the white campaign against the 'Old' ones, the Chickamaugans. However, their assistance to the whites was rewarded by the infamous 'Trail of Tears'.

Please re-integrate into the article what makes sense in this mess ;-) --Magnus Manske 13:23 Jan 3, 2003 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Talk:Ani Hyuntikwalaski


text:
Elias Disney

Elias Charles Disney (February 6, 1859 – September 13, 1941) was an Irish-Canadian-American construction worker and entrepreneur. He is best known as the father of Roy and Walt Disney, co-founders of The Walt Disney Company.

Early life
Disney was born in the rural village of Bluevale, in what is now Ontario, Canada, to Irish Protestant immigrants Kepple Elias Disney (1832–1891) and Mary Disney (née Richardson) (1838–1909). Both parents had emigrated from Freshford, County Kilkenny in Ireland to Canada as children, accompanying their parents. His parents would have eight other children in the following 18 years after the birth of Elias. Disney's father owned a farm and got into a variety of other business ventures to make money.

He moved to California with his father in 1878 in hopes of finding gold. Instead, Kepple was convinced by an agent of the Union Pacific Railroad to buy 200 acre of land near Ellis, Kansas. When the family moved, they would let go of their previously conservative ways with the exception of Elias. In Ellis, Disney attempted to live as an orange grower and failed.

Career

Disney worked on his father's new farm until 1884, when he left to find another job. He was hired in a railroad machine shop for the Kansas Pacific Railroad (one of his co-workers was Walter Chrysler), then he joined the railroad crew building the Union Pacific line through Colorado. After the railroad contract was over, he became a professional fiddle player in Denver. Again he was unsuccessful, and he returned to his father's farm.

His sister Annie would become a teacher at the Beaver Bank School located adjacent to the family farms starting in 1884. Elias would sometimes fill in as a substitute teacher for his sister, and there he started to get to know and eventually develop a relationship with one of her students, Flora Call. After she graduated, Flora's parents would sell their land in Ellis and move to Acron, Florida, with Disney following suit wanting to be with Flora. Elias and Flora were married in Acron on January 1, 1888. Their marriage license was the first license ever issued by Lake County. Disney and his wife would move to Daytona Beach and manage the Halifax Hotel during the "tourist season of 1888" but left when the owner no longer needed a manager and kicked the two out of their rooms. They would have a son, Herbert, in December 1888. He also worked for a short time as a mailman in Kissimmee, Florida, close to the eventual site of Walt Disney World. Disney also attempted to make a career as an orange grower in Kissimmee, buying 160 acre, but he was unsuccessful. After this he would decide to move to Chicago, leaving Florida during the late spring of 1890. Although frequently unsuccessful at self-employment, Disney's entrepreneurial tendencies were passed on to his son Walt.

He would be a construction worker for the 1893 World's Columbian Exposition in Chicago, an event which author Erik Larson suggests was a source of inspiration for his son Walt and the Disney kingdom he would eventually create. He bought shares of O-Zell Company, a jelly-canning factory that also produced apple juice in Chicago, where his son Walt Disney worked before he joined the Red Cross Ambulance Corps in World War I. The family would live at 3515 South Vernon Avenue in the Fourth Ward by 1890. On October 31, 1891, Disney bought a lot at 1249 Tripp Avenue By 1892, he had built a house on it. The neighborhood was called Hermosa and had been settled by Scottish, German, and Scandinavian immigrants. Their next two children were born there. The family would move into the new home located on Tripp Avenue on June 24, 1893, and shortly afterwards Flora give birth to a baby boy, Roy O. Disney. Disney wanted to name him Columbus but Flora wanted him to be named Roy instead, and Roy was picked. When it came to deciding on a middle name, there would be issues. One day, Flora saw a lumber truck on Tripp Avenue with the company name of Oliver Lumber Company painted across the sides of it. After seeing this truck, Elias and Flora would decide that Oliver would be Roy's middle name.

By the turn of the century, Disney had become an active building contractor. He built houses which he owned and then resold. He also built the Saint Paul Congregational Church, a building dedicated on October 14, 1900. Disney was one of the church's trustees, while his wife was its treasurer.

A neighboring family had two adolescent children involved in a car barn robbery, and Disney feared that crime would taint his own children. On March 5, 1906, he bought a 40 acre farm near Marceline, Missouri, for $3,000, or $75 per acre. Its previous owner William E. Crane had died in November 1905. Crane was a veteran of the American Civil War, and his house predated the foundation of Marceline. On April 3, Disney bought an adjoining tract of about 5 acre from Crane's widow for an additional $450. Marceline was still accessible from Chicago but provided a rural setting, and Disney's younger brother Robert owned a 440 acre farm west of the city. Disney and his family settled on the farm in April.

The Crane Farm had orchards of apples, peaches, and plums and fields of grain. The farm animals included pigs, chickens, horses, and cows. The Disneys had a telephone connection by 1907. In 1907, Disney convinced some of his fellow farmers to join the American Society of Equity, a farmer's union aiming to consolidate the members' buying power.

Herbert and Raymond Disney never liked life on the farm. They moved out around the fall of 1908, heading back to Chicago, where they found work as clerks.

The family sold the farm on November 28, 1910, as Disney fell ill. He was suffering from typhoid fever, followed by pneumonia. The Disneys lived in a rented house in Marceline, probably at 508 North Kansas Avenue, until 1911, when they moved to Kansas City, Missouri. They lived in a rented house at 2706 East Thirty-first Street. They stayed there until they bought their own modest home in September 1914. It was situated at 3028 Bellefontaine Street.

On July 1, 1911, Disney purchased a newspaper delivery route for The Kansas City Star. It extended from the Twenty-seventh Street to the Thirty-first Street, and from Prospect Avenue to Indiana Avenue. Roy and Walt were put to work delivering the newspapers. The Disneys delivered the morning newspaper Kansas City Times to about 700 customers and the evening and Sunday Star to more than 600. Their customers increased with time. Disney also delivered butter and eggs to his newspaper customers. They were imported from a dairy farm in Marceline.

Disney sold the paper route on March 17, 1917. He had been investing in the O-Zell Company of Chicago since 1912 and moved back to the city in 1917 to take an active role in its management. The Disneys rented a flat at 1523 Ogden Avenue.

He retired from management work in 1920 and moved back to Kansas City. He was again listed as a carpenter. He moved to Portland, Oregon, by the fall (autumn September–October) of 1921. His son Herbert had earlier moved to this city.

Personal life and death
Disney married Flora Call on January 1, 1888, in Kismet, Lake County, Florida, 50 mi north of the land on which Walt Disney World would eventually be built and lived for a short time in adjoining Acron, Florida. She was the daughter of his father's neighbors.

Soon after marriage, the Disneys moved to Chicago, Illinois, where Disney met and befriended Walter Parr, St. Paul Congregational Church's preacher for whom the Disneys' fourth son Walt was named.

The couple had five children:
 * Herbert Arthur Disney (December 8, 1888 – January 29, 1961, aged 72), letter carrier (1940 US Census)
 * Raymond Arnold Disney (December 30, 1890 – May 24, 1989, aged 98), self-employed insurance broker (1940 US Census)
 * Roy Oliver Disney (June 24, 1893 – December 20, 1971, aged 78), businessman and co-founder of The Walt Disney Company
 * Walter "Walt" Elias Disney (December 5, 1901 – December 15, 1966, aged 65), entrepreneur and co-founder of The Walt Disney Company
 * Ruth Flora Disney (December 6, 1903 – April 7, 1995, aged 91), philanthropist

Disney was a member of the Congregational Church and often preached stern sermons on Sundays in this church. His son Walter Elias Disney was named after a Congregationalist minister named Walter Parr. Disney and Walt had a tense relationship as Disney never saw Walt's profession as an artist as a real job.

Disney's son Raymond Arnold Disney named his son Charles Elias Disney after his father Elias Charles Disney.

Disney died on September 13, 1941, in Los Angeles aged 82. He is interred in Forest Lawn Memorial Park at Glendale, California.

Beliefs and habits
Disney never drank alcohol and rarely smoked. According to biographical accounts, Disney was a stern man who could have a strong temper at times and would take the money his sons earned for "safekeeping," considering them too young to know the value of money. If his children misbehaved, Disney would not hesitate to punish them with a switch.

Disney was an ardent socialist and a supporter of Eugene Debs. Disney would talk socialism with various people and bring them home. He was a fiddler and would bring home anyone else who could play an instrument.

title: Elias Disney


text:
Soil formation

Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order (anisotropy) within soils. These alterations lead to the development of layers, termed soil horizons, distinguished by differences in color, structure, texture, and chemistry. These features occur in patterns of soil type distribution, forming in response to differences in soil forming factors.

Pedogenesis is studied as a branch of pedology, the study of soil in its natural environment. Other branches of pedology are the study of soil morphology and soil classification. The study of pedogenesis is important to understanding soil distribution patterns in current (soil geography) and past (paleopedology) geologic periods.

Overview
Soil develops through a series of changes. The starting point is weathering of freshly accumulated parent material. A variety of soil microbes (bacteria, archaea, fungi) feed on simple compounds (nutrients) released by weathering and produce organic acids and specialized proteins which contribute in turn to mineral weathering. They also leave behind organic residues which contribute to humus formation. Plant roots with their symbiotic mycorrhizal fungi are also able to extract nutrients from rocks.

New soils increase in depth by a combination of weathering and further deposition. The soil production rate due to weathering is approximately 1/10 mm per year. New soils can also deepen from dust deposition. Gradually soil is able to support higher forms of plants and animals, starting with pioneer species and proceeding along ecological succession to more complex plant and animal communities. Topsoils deepen with the accumulation of humus originating from dead remains of higher plants and soil microbes. They also deepen through mixing of organic matter with weathered minerals. As soils mature, they develop soil horizons as organic matter accumulates and mineral weathering and leaching take place.

Factors
Soil formation is influenced by at least five classic factors that are intertwined in the evolution of a soil. They are: parent material, climate, topography (relief), organisms, and time. When reordered to climate, organisms, relief, parent material, and time, they form the acronym CLORPT.

Parent material
The mineral material from which a soil forms is called parent material. Rock, whether its origin is igneous, sedimentary, or metamorphic, is the source of all soil mineral materials and the origin of all plant nutrients with the exceptions of nitrogen, hydrogen and carbon. As the parent rock is chemically and physically weathered, transported, deposited and precipitated, it is transformed into a soil.

Typical soil parent mineral materials are:
 * Quartz: SiO2
 * Calcite: CaCO3
 * Feldspar: KAlSi3O8
 * Mica (biotite):

Parent materials are classified according to how they came to be deposited. Residual materials are mineral materials that have weathered in place from primary bedrock. Transported materials are those that have been deposited by water, wind, ice or gravity. Cumulose material is organic matter that has grown and accumulates in place.

Residual soils are soils that develop from their underlying parent rocks and have the same general chemistry as those rocks. The soils found on mesas, plateaux, and plains are residual soils. In the United States as little as three percent of the soils are residual.

Most soils derive from transported materials that have been moved many miles by wind, water, ice and gravity:
 * Aeolian processes (movement by wind) are capable of moving silt and fine sand many hundreds of miles, forming loess soils (60–90 percent silt), common in the Midwestern United States and Canada, north-western Europe, Argentina and Central Asia. Clay is seldom moved by wind as it forms stable aggregates.
 * Water-transported materials are classed as either alluvial, lacustrine, or marine. Alluvial materials are those moved and deposited by flowing water. Sedimentary deposits settled in lakes are called lacustrine. Lake Bonneville and many soils around the Great Lakes are examples. Marine deposits, such as soils along the Atlantic and Gulf Coasts and in the Imperial Valley of California are the beds of ancient seas that have been revealed as the land uplifted.
 * Ice moves parent material and makes deposits in the form of terminal and lateral moraines in the case of stationary glaciers. Retreating glaciers leave smoother ground moraines, and in all cases outwash plains are left as alluvial deposits are moved downstream from the glacier.
 * Parent material moved by gravity is obvious at the base of steep slopes as talus cones and is called colluvial material.

Cumulose parent material is not moved but originates from deposited organic material. This includes peat and muck soils and results from preservation of plant residues by the low oxygen content of a high water table. While peat may form sterile soils, muck soils may be very fertile.

Weathering
The weathering of parent material takes the form of physical weathering (disintegration), chemical weathering (decomposition) and chemical transformation. Weathering is usually confined to the top few meters of geologic material, because physical, chemical, and biological stresses and fluctuations generally decrease with depth. Physical disintegration begins as rocks that have solidified deep in the Earth are exposed to lower pressure near the surface and swell and become mechanically unstable. Chemical decomposition is a function of mineral solubility, the rate of which doubles with each 10 °C rise in temperature but is strongly dependent on water to effect chemical changes. Rocks that will decompose in a few years in tropical climates will remain unaltered for millennia in deserts. Structural changes are the result of hydration, oxidation, and reduction. Chemical weathering mainly results from the excretion of organic acids and chelating compounds by bacteria and fungi, thought to increase under greenhouse effect.
 * Physical disintegration is the first stage in the transformation of parent material into soil. Temperature fluctuations cause expansion and contraction of the rock, splitting it along lines of weakness. Water may then enter the cracks and freeze and cause the physical splitting of material along a path toward the center of the rock, while temperature gradients within the rock can cause exfoliation of "shells". Cycles of wetting and drying cause soil particles to be abraded to a finer size, as does the physical rubbing of material as it is moved by wind, water, and gravity. Organisms may reduce parent material size and create crevices and pores through the mechanical action of plant roots and the digging activity of animals.
 * Chemical decomposition and structural changes result when minerals are made soluble by water or are changed in structure. The first three of the following list are solubility changes, and the last three are structural changes.

 * 1) The solution of salts in water results from the action of bipolar water molecules on ionic salt compounds producing a solution of ions and water, removing those minerals and reducing the rock's integrity, at a rate depending on water flow and pore channels.
 * 2) Hydrolysis is the transformation of minerals into polar molecules by the splitting of intervening water. This results in soluble acid-base pairs. For example, the hydrolysis of orthoclase-feldspar transforms it to acid silicate clay and basic potassium hydroxide, both of which are more soluble.
 * 3) In carbonation, the solution of carbon dioxide in water forms carbonic acid. Carbonic acid will transform calcite into more soluble calcium bicarbonate.
 * 4) Hydration is the inclusion of water in a mineral structure, causing it to swell and leaving it stressed and easily decomposed.
 * 5) Oxidation of a mineral compound is the inclusion of oxygen in a mineral, causing it to increase its oxidation number and swell due to the relatively large size of oxygen, leaving it stressed and more easily attacked by water (hydrolysis) or carbonic acid (carbonation).
 * 6) Reduction, the opposite of oxidation, means the removal of oxygen, hence the oxidation number of some part of the mineral is reduced, which occurs when oxygen is scarce. The reduction of minerals leaves them electrically unstable, more soluble and internally stressed and easily decomposed. It mainly occurs in waterlogged conditions.

Of the above, hydrolysis and carbonation are the most effective, in particular in regions of high rainfall, temperature and physical erosion. Chemical weathering becomes more effective as the surface area of the rock increases, thus is favoured by physical disintegration. This stems in latitudinal and altitudinal climate gradients in regolith formation.

Saprolite is a particular example of a residual soil formed from the transformation of granite, metamorphic and other types of bedrock into clay minerals. Often called weathered granite, saprolite is the result of weathering processes that include: hydrolysis, chelation from organic compounds, hydration and physical processes that include freezing and thawing. The mineralogical and chemical composition of the primary bedrock material, its physical features (including grain size and degree of consolidation), and the rate and type of weathering transforms the parent material into a different mineral. The texture, pH and mineral constituents of saprolite are inherited from its parent material. This process is also called arenization, resulting in the formation of sandy soils, thanks to the much higher resistance of quartz compared to other mineral components of granite (e.g., mica, amphibole, feldspar).

Climate
The principal climatic variables influencing soil formation are effective precipitation (i.e., precipitation minus evapotranspiration) and temperature, both of which affect the rates of chemical, physical, and biological processes. Temperature and moisture both influence the organic matter content of soil through their effects on the balance between primary production and decomposition: the colder or drier the climate the lesser atmospheric carbon is fixed as organic matter while the lesser organic matter is decomposed. Climate also indirectly influences soil formation through the effects of vegetation cover and biological activity, which modify the rates of chemical reactions in the soil.

Climate is the dominant factor in soil formation, and soils show the distinctive characteristics of the climate zones in which they form, with a feedback to climate through transfer of carbon stocked in soil horizons back to the atmosphere. If warm temperatures and abundant water are present in the profile at the same time, the processes of weathering, leaching, and plant growth will be maximized. According to the climatic determination of biomes, humid climates favor the growth of trees. In contrast, grasses are the dominant native vegetation in subhumid and semiarid regions, while shrubs and brush of various kinds dominate in arid areas.

Water is essential for all the major chemical weathering reactions. To be effective in soil formation, water must penetrate the regolith. The seasonal rainfall distribution, evaporative losses, site topography, and soil permeability interact to determine how effectively precipitation can influence soil formation. The greater the depth of water penetration, the greater the depth of weathering of the soil and its development. Surplus water percolating through the soil profile transports soluble and suspended materials from the upper layers (eluviation) to the lower layers (illuviation), including clay particles and dissolved organic matter. It may also carry away soluble materials in the surface drainage waters. Thus, percolating water stimulates weathering reactions and helps differentiate soil horizons.

Likewise, a deficiency of water is a major factor in determining the characteristics of soils of dry regions. Soluble salts are not leached from these soils, and in some cases they build up to levels that curtail plant and microbial growth. Soil profiles in arid and semi-arid regions are also apt to accumulate carbonates and certain types of expansive clays (calcrete or caliche horizons). In tropical soils, when the soil has been deprived of vegetation (e.g. by deforestation) and thereby is submitted to intense evaporation, the upward capillary movement of water, which has dissolved iron and aluminum salts, is responsible for the formation of a superficial hard pan of laterite or bauxite, respectively, which is improper for cultivation, a known case of irreversible soil degradation.

The direct influences of climate include:
 * A shallow accumulation of lime in low rainfall areas as caliche
 * Formation of acid soils in humid areas
 * Erosion of soils on steep hillsides
 * Deposition of eroded materials downstream
 * Very intense chemical weathering, leaching, and erosion in warm and humid regions where soil does not freeze

Climate directly affects the rate of weathering and leaching. Wind moves sand and smaller particles (dust), especially in arid regions where there is little plant cover, depositing it close to or far from the entrainment source. The type and amount of precipitation influence soil formation by affecting the movement of ions and particles through the soil, and aid in the development of different soil profiles. Soil profiles are more distinct in wet and cool climates, where organic materials may accumulate, than in wet and warm climates, where organic materials are rapidly consumed. The effectiveness of water in weathering parent rock material depends on seasonal and daily temperature fluctuations, which favour tensile stresses in rock minerals, and thus their mechanical disaggregation, a process called thermal fatigue. By the same process freeze-thaw cycles are an effective mechanism which breaks up rocks and other consolidated materials.

Topography
The topography, or relief, is characterized by the inclination (slope), elevation, and orientation of the terrain (aspect). Topography determines the rate of precipitation or runoff and the rate of formation or erosion of the surface soil profile. The topographical setting may either hasten or retard the work of climatic forces.

Steep slopes encourage rapid soil loss by erosion and allow less rainfall to enter the soil before running off and hence, little mineral deposition in lower profiles (illuviation). In semiarid regions, the lower effective rainfall on steeper slopes also results in less complete vegetative cover, so there is less plant contribution to soil formation. For all of these reasons, steep slopes prevent the formation of soil from getting very far ahead of soil destruction. Therefore, soils on steep terrain tend to have rather shallow, poorly developed profiles in comparison to soils on nearby, more level sites.

Topography determines exposure to weather, fire, and other forces of man and nature. Mineral accumulations, plant nutrients, type of vegetation, vegetation growth, erosion, and water drainage are dependent on topographic relief. Soils at the bottom of a hill will get more water than soils on the slopes, and soils on the slopes that face the sun's path will be drier than soils on slopes that do not.

In swales and depressions where runoff water tends to concentrate, the regolith is usually more deeply weathered, and soil profile development is more advanced. However, in the lowest landscape positions, water may saturate the regolith to such a degree that drainage and aeration are restricted. Here, the weathering of some minerals and the decomposition of organic matter are retarded, while the loss of iron and manganese is accelerated. In such low-lying topography, special profile features characteristic of wetland soils may develop. Depressions allow the accumulation of water, minerals and organic matter, and in the extreme, the resulting soils will be saline marshes or peat bogs.

Recurring patterns of topography result in toposequences or soil catenas. These patterns emerge from topographic differences in erosion, deposition, fertility, soil moisture, plant cover, soil biology, fire history, and exposure to the elements. Gravity transports water downslope, together with mineral and organic solutes and colloids, increasing particulate and base content at the foot of hills and mountains. However, many other factors like drainage and erosion interact with slope position, blurring its expected influence on crop yield.

Organisms
Each soil has a unique combination of microbial, plant, animal and human influences acting upon it. Microorganisms are particularly influential in the mineral transformations critical to the soil forming process. Additionally, some bacteria can fix atmospheric nitrogen, and some fungi are efficient at extracting deep soil phosphorus and increasing soil carbon levels in the form of glomalin. Plants hold soil against erosion, and accumulated plant material build soil humus levels. Plant root exudation supports microbial activity. Animals serve to decompose plant materials and mix soil through bioturbation.

Soil is the most speciose (species-rich) ecosystem on Earth, but the vast majority of organisms in soil are microbes, a great many of which have not been described. There may be a population limit of around one billion cells per gram of soil, but estimates of the number of species vary widely from 50,000 per gram to over a million per gram of soil. The number of organisms and species can vary widely according to soil type, location, and depth.

Plants, animals, fungi, bacteria and humans affect soil formation (see soil biomantle and stonelayer). Soil animals, including fauna and soil mesofauna, mix soils as they form burrows and pores, allowing moisture and gases to move about, a process called bioturbation. In the same way, plant roots penetrate soil horizons and open channels upon decomposition. Plants with deep taproots can penetrate many metres through the different soil layers to bring up nutrients from deeper in the profile. Plants have fine roots that excrete organic compounds (sugars, organic acids, mucilage), slough off cells (in particular at their tip), and are easily decomposed, adding organic matter to soil, a process called rhizodeposition.

Microorganisms, including fungi and bacteria, effect chemical exchanges between roots and soil and act as a reserve of nutrients in a soil biological hotspot called rhizosphere. The growth of roots through the soil stimulates microbial populations, stimulating in turn the activity of their predators (notably amoeba), thereby increasing the mineralization rate, and in last turn root growth, a positive feedback called the soil microbial loop. Out of root influence, in the bulk soil most bacteria are in a quiescent stage, forming micro-aggregates, i.e. mucilaginous colonies to which clay particles are glued, offering them a protection against desiccation and predation by soil microfauna (bacteriophagous protozoa and nematodes). Microaggregates (20–250 μm) are ingested by soil mesofauna and fauna, and bacterial bodies are partly or totally digested in their guts.

Humans impact soil formation by removing vegetation cover through tillage, application of biocides, fire and leaving soils bare. This can lead to erosion, waterlogging, lateritization or podzolization (according to climate and topography). Tillage mixes the different soil layers, restarting the soil formation process as less weathered material is mixed with the more developed upper layers, resulting in net increased rate of mineral weathering.

Earthworms, ants, termites, moles, gophers, as well as some millipedes and tenebrionid beetles, mix the soil as they burrow, significantly affecting soil formation. Earthworms ingest soil particles and organic residues, enhancing the availability of plant nutrients in the material that passes through their bodies. They aerate and stir the soil and create stable soil aggregates, after having disrupted links between soil particles during the intestinal transit of ingested soil, thereby assuring ready infiltration of water. As ants and termites build mounds, earthworms transport soil materials from one horizon to another. Other important functions are fulfilled by earthworms in the soil ecosystem, in particular their intense mucus production, both within the intestine and as a lining in their galleries, exert a priming effect on soil microflora, giving them the status of ecosystem engineers, which they share with ants and termites.

In general, the mixing of the soil by the activities of animals, sometimes called pedoturbation, tends to undo or counteract the tendency of other soil-forming processes that create distinct horizons. Termites and ants may also retard soil profile development by denuding large areas of soil around their nests, leading to increased loss of soil by erosion. Large animals such as gophers, moles, and prairie dogs bore into the lower soil horizons, bringing materials to the surface. Their tunnels are often open to the surface, encouraging the movement of water and air into the subsurface layers. In localized areas, they enhance mixing of the lower and upper horizons by creating and later refilling the tunnels. Old animal burrows in the lower horizons often become filled with soil material from the overlying A horizon, creating profile features known as crotovinas.

Vegetation impacts soils in numerous ways. It can prevent erosion caused by excessive rain that might result from surface runoff. Plants shade soils, keeping them cooler and slowing evaporation of soil moisture. Conversely, by way of transpiration, plants can cause soils to lose moisture, resulting in complex and highly variable relationships between leaf area index (measuring light interception) and moisture loss: more generally plants prevent soil from desiccation during driest months while they dry it during moister months, thereby acting as a buffer against strong moisture variation. Plants can form new chemicals that can break down minerals, both directly and indirectly through mycorrhizal fungi and rhizosphere bacteria, and improve the soil structure. The type and amount of vegetation depend on climate, topography, soil characteristics and biological factors, mediated or not by human activities. Soil factors such as density, depth, chemistry, pH, temperature and moisture greatly affect the type of plants that can grow in a given location. Dead plants and fallen leaves and stems begin their decomposition on the surface. There, organisms feed on them and mix the organic material with the upper soil layers; these added organic compounds become part of the soil formation process.

The influence of humans, and by association, fire, are state factors placed within the organisms state factor. Humans can import or extract nutrients and energy in ways that dramatically change soil formation. Accelerated soil erosion from overgrazing, and Pre-Columbian terraforming the Amazon basin resulting in terra preta are two examples of the effects of human management.

It is believed that Native Americans regularly set fires to maintain several large areas of prairie grasslands in Indiana and Michigan, although climate and mammalian grazers (e.g. bisons) are also advocated to explain the maintenance of the Great Plains of North America. In more recent times, human destruction of natural vegetation and subsequent tillage of the soil for crop production has abruptly modified soil formation. Likewise, irrigating soil in an arid region drastically influences soil-forming factors, as does adding fertilizer and lime to soils of low fertility.

Distinct ecosystems produce distinct soils, sometimes in easily observable ways. For example, three species of land snails in the genus Euchondrus in the Negev desert are noted for eating lichens growing under the surface limestone rocks and slabs (endolithic lichens). The grazing activity of these ecosystem engineers disrupts the limestone, resulting in the weathering and the subsequent formation of soil. They have a significant effect on the region: the population of snails is estimated to process between 0.7 and 1.1 metric ton per hectare per year of limestone in the Negev desert.

The effects of ancient ecosystems are not as easily observed, and this challenges the understanding of soil formation. For example, the chernozems of the North American tallgrass prairie have a humus fraction nearly half of which is charcoal. This outcome was not anticipated because the antecedent prairie fire ecology capable of producing these distinct deep rich black soils is not easily observed.

Time
Time is a factor in the interactions of all the above. While a mixture of sand, silt and clay constitute the texture of a soil and the aggregation of those components produces peds, the development of a distinct B horizon marks the development of a soil or pedogenesis. With time, soils will evolve features that depend on the interplay of the prior listed soil-forming factors. It takes decades to several thousand years for a soil to develop a profile, although the notion of soil development has been criticized, soil being in a constant state-of-change under the influence of fluctuating soil-forming factors. That time period depends strongly on climate, parent material, relief, and biotic activity. For example, recently deposited material from a flood exhibits no soil development as there has not been enough time for the material to form a structure that further defines soil. The original soil surface is buried, and the formation process must begin anew for this deposit. Over time the soil will develop a profile that depends on the intensities of biota and climate. While a soil can achieve relative stability of its properties for extended periods, the soil life cycle ultimately ends in soil conditions that leave it vulnerable to erosion. Despite the inevitability of soil retrogression and degradation, most soil cycles are long.

Soil-forming factors continue to affect soils during their existence, even on stable landscapes that are long-enduring, some for millions of years. Materials are deposited on top or are blown or washed from the surface. With additions, removals and alterations, soils are always subject to new conditions. Whether these are slow or rapid changes depends on climate, topography and biological activity.

Time as a soil-forming factor may be investigated by studying soil chronosequences, in which soils of different ages but with minor differences in other soil-forming factors can be compared. Paleosols are soils formed during previous soil forming conditions.

Dokuchaev's equation
Russian geologist Vasily Dokuchaev, commonly regarded as the father of pedology, determined in 1883 that soil formation occurs over time under the influence of climate, vegetation, topography, and parent material. He demonstrated this in 1898 using the soil forming equation:

(where cl or c = climate, o = biological processes, p = parent material) tr = relative time (young, mature, old)

Hans Jenny's state equation
American soil scientist Hans Jenny published in 1941 a state equation for the factors influencing soil formation:

 *  S  soil formation
 *  cl  (sometimes  c ) climate
 *  o  organisms (soil microbiology, soil mesofauna, soil biology)
 *  r  relief
 *  p  parent material
 *  t  time

This is often remembered with the mnemonic Clorpt.

Jenny's state equation in Factors of Soil Formation differs from the Vasily Dokuchaev equation, treating time (t) as a factor, adding topographic relief (r), and pointedly leaving the ellipsis "open" for more factors (state variables) to be added as our understanding becomes more refined.

There are two principal methods by which the state equation may be solved: first in a theoretical or conceptual manner by logical deductions from certain premises, and second empirically by experimentation or field observation. The empirical method is still mostly employed today, and soil formation can be defined by varying a single factor and keeping the other factors constant. This had led to the development of empirical models to describe pedogenesis, such as climofunctions, biofunctions, topofunctions, lithofunctions, and chronofunctions. Since Jenny published his formulation in 1941, it has been used by innumerable soil surveyors all over the world as a qualitative list for understanding the factors that may be important for producing the soil pattern within a region.

<!-- All covered above... ==Soil forming processes== Soils develop from parent material by various weathering processes. Organic matter accumulation, decomposition, and humification are as critically important to soil formation as weathering. The zone of humification and weathering where pedogenic processes are dominant and where biota play an important role is termed the solum.

Soil acidification resulting from soil respiration supports chemical weathering. Plants contribute to chemical weathering through root exudates. Soils can be enriched by deposition of sediments on floodplains and alluvial fans, and by wind-borne deposits.

Soil mixing (pedoturbation) is often an important factor in soil formation. Pedoturbation includes churning clays, cryoturbation, and bioturbation. Types of bioturbation include faunal pedoturbation (animal burrowing), plant pedoturbation (root growth, tree uprooting), and fungal pedoturbation (mycelial growth). Pedoturbation transforms soils through destratification, mixing, and sorting, as well as creating preferential flow paths for soil gas and infiltrating water. The zone of active bioturbation is termed the soil biomantle.

Soil moisture content and water flow through the soil profile support leaching of solutes, and eluviation. Eluviation is the translocation of colloid material, such as organic matter, clay and other mineral compounds. Transported constituents are deposited due to differences in soil moisture and soil chemistry, especially soil pH and redox potential. The interplay of removal (eluviation) and deposition (illuviation), also called pedotranslocation, results in contrasting soil horizons.

Key soil-forming processes especially important to macro-scale patterns of soil formation are:
 * Laterization
 * Podsolization
 * Calcification
 * Salinization
 * Gleization-->

Example
An example of the evolution of soils in prehistoric lake beds is in the Makgadikgadi Pans of the Kalahari Desert, where change in an ancient river course led to millennia of salinity buildup and formation of calcretes and silcretes.

title: Soil formation


text:
Sudden stratospheric warming

A sudden stratospheric warming (SSW) is an event in which polar stratospheric temperatures rise by several tens of kelvins (up to increases of about 50 °C (90 °F)) over the course of a few days. The warming is preceded by a slowing then reversal of the westerly winds in the stratospheric polar vortex. SSWs occur about six times per decade in the northern hemisphere, and about once every 20-30 years in the southern hemisphere. Only two southern SSWs have been observed.

History
The first continued measurements of the stratosphere were taken by Richard Scherhag in 1951 using radiosondes to take reliable temperature readings in the upper stratosphere (~40 km) and he became the first to observe stratospheric warming on 27 January 1952. After his discovery, he assembled a team of meteorologists specifically to study the stratosphere at the Free University of Berlin and this group continued to map the northern-hemisphere stratospheric temperature and geopotential height for many years using radiosondes and rocketsondes.

In 1979 when the satellite era began, meteorological measurements became far more frequent. Although satellites were primarily used for the troposphere they also recorded data for the stratosphere. Today both satellites and stratospheric radiosondes are used to take measurements of the stratosphere.

Classification and description
SSW is closely associated with polar vortex breakdown. Meteorologists typically classify vortex breakdown into three categories: major, minor, and final. No unambiguous standard definition of these has so far been adopted. However, differences in the methodology to detect SSWs are not relevant as long as circulation in the polar stratosphere reverses. "Major SSWs occur when the winter polar stratospheric westerlies reverse to easterlies. In minor warmings, the polar temperature gradient reverses but the circulation does not, and in final warmings, the vortex breaks down and remains easterly until the following boreal autumn".

Sometimes a fourth category, the Canadian warming, is included because of its unique and distinguishing structure and evolution.

"There are two main types of SSW: displacement events in which the stratospheric polar vortex is displaced from the pole and split events in which the vortex splits into two or more vortices. Some SSWs are a combination of both types".

Major
These occur when the westerly winds at 60N and 10 hPa reverse, i.e. become easterly. A complete disruption of the polar vortex is observed and the vortex will either be split into daughter vortices, or displaced from its normal location over the pole.

According to the World Meteorological Organization's Commission for Atmospheric Sciences: a stratospheric warming can be said to be major if at 10 mb or below the latitudinal mean temperature increases poleward from 60 degree latitude and an associated circulation reversal is observed (that is, the prevailing mean westerly winds poleward of 60 latitude are succeeded by mean easterlies in the same area).

Minor
Minor warmings are similar to major warmings however they are less dramatic, the westerly winds are slowed, however do not reverse. Therefore, a breakdown of the vortex is never observed.

Mclnturff cites the WMOs's Commission for Atmospheric Sciences: ''a stratospheric warming is called minor if a significant temperature increase is observed (that is, at least 25 degrees in a period of week or less) at any stratospheric level in any area of winter time hemisphere. The polar vortex is not broken down and the wind reversal from westerly to easterly is less extensive.''

Final
The radiative cycle in the stratosphere means that during winter the mean flow is westerly and during summer it is easterly (westward). A final warming occurs on this transition, so that the polar vortex winds change direction for the warming and do not change back until the following winter. This is because the stratosphere has entered the summer easterly phase. It is final because another warming cannot occur over the summer, so it is the final warming of the current winter.

Canadian
Canadian warmings occur in early winter in the stratosphere of the Northern Hemisphere, typically from mid November to early December. They have no counterpart in the southern hemisphere.

Dynamics
In a usual northern-hemisphere winter, several minor warming events occur, with a major event occurring roughly every two years. One reason for major stratospheric warmings to occur in the Northern hemisphere is because orography and land-sea temperature contrasts are responsible for the generation of long (wavenumber 1 or 2) Rossby waves in the troposphere. These waves travel upward to the stratosphere and are dissipated there, decelerating the westerly winds and warming the Arctic. This is the reason that major warmings are only observed in the northern-hemisphere, with two exceptions. In 2002 and 2019, southern-hemisphere major warmings were observed. These events are not fully understood.

At an initial time a blocking-type circulation pattern establishes in the troposphere. This blocking pattern causes Rossby waves with zonal wavenumber 1 and/or 2 to grow to unusually large amplitudes. The growing wave propagates into the stratosphere and decelerates the westerly mean zonal winds. Thus the polar night jet weakens and simultaneously becomes distorted by the growing planetary waves. Because the wave amplitude increases with decreasing density this easterly acceleration process is not effective at fairly high levels. If the waves are sufficiently strong the mean zonal flow may decelerate sufficiently so that the winter westerlies turn easterly. At this point planetary waves may no longer penetrate into the stratosphere ). Hence further upward transfer of energy is completely blocked and a very rapid easterly acceleration and the polar warming occur at this critical level, which must then move downward until eventually the warming and zonal wind reversal affect the entire polar stratosphere. The upward propagation of planetary waves and their interaction with the stratospheric mean flow is traditionally diagnosed via so-called Eliassen-Palm fluxes.

There exists a link between sudden stratospheric warmings and the quasi-biennial oscillation: If the QBO is in its easterly phase, the atmospheric waveguide is modified in such a way that upward-propagating Rossby waves are focused on the polar vortex, intensifying their interaction with the mean flow. Thus, there exists a statistically significant imbalance between the frequency of sudden stratospheric warmings if these events are grouped according to the QBO phase (easterly or westerly).

Weather effects
Although sudden stratospheric warmings are mainly forced by planetary scale waves which propagate up from the lower atmosphere, there is also a subsequent return effect of sudden stratospheric warmings on surface weather. Following a sudden stratospheric warming, the high altitude westerly winds reverse and are replaced by easterlies. The easterly winds progress down through the atmosphere, often leading to a weakening of the tropospheric westerly winds, resulting in dramatic reductions in temperature in Northern Europe. This process can take a few days to a few weeks to occur.

== Table of Major mid-winter Sudden Stratospheric Warming Events in Reanalyses Products ==

title: Sudden stratospheric warming


text:
Annual cycle

An annual cycle refers to a set of changes or events that uniformly, or consistently, take place at the same time of year.

In biology, the annual cycle for plants and animals details behavioral and chemical changes that take place as the seasons advance.

In business, a business cycle refers to the way modelling and analysis is applied to the periodic development and marketing of new products and services.

In religion, the annual cycle refers to the various celebrations or memorials that occur in the same sequence from year to year. For example, in Christianity the liturgical year is an annual cycle, which for some Christian denominations is composed of the temporal cycle that tracks the events in the life of Christ, and the sanctoral cycle which tracks the various saint's days. Some Christian churches only observe the temporal cycle.

In climatology, an annual cycle is the part of a measured quantity's fluctuation that is attributed to Earth's changing position in orbit over the course of the year. Such quantities might be influenced directly (e.g. incoming solar radiation at a point at the surface) or indirectly (e.g. stratospheric westerlies and easterlies over the winter and summer hemispheres, respectively) by orbital position.

Mathematically, the climatological annual cycle is commonly estimated from observational data or model output by taking the average of all Januaries, all Februaries, and so forth. If the observational record is long enough and conditions are stationary (i.e. there is no significant long-term trend), a meaningful annual cycle will result that can be used to calculate an anomaly time series.

title: Annual cycle


text:
LTC

LTC may refer to:

Organizations

 * Lakeshore Technical College, Cleveland, Wisconsin, US
 * Latino Theater Company, Los Angeles, California, US
 * Licensed Trade Charity, UK
 * Linear Technology Corporation, Milpitas, California, US
 * Linux Technology Center, in IBM
 * London Transit Commission, Ontario, Canada

Science, technology, and medicine

 * Linear timecode, encoded in audio signal
 * Long-term care, of the chronically ill
 * Litecoin, a peer-to-peer digital currency
 * Coordinated Lunar Time, lunar standard time

Other uses

 * Leave Travel Concession; see LTC Scam
 * Light timber construction schools, Australia
 * Lieutenant colonel in the US Army
 * License To Carry firearms in some US states (concealed carry in the United States)
 * Load Tap Changer, for adjusting transformer voltage at substations.
 * Losing-Trick Count, for evaluating bridge hands
 * ltc, the ISO 639-3 and Linguist List code for Middle Chinese

title: LTC


text:
Talk:Fluoxetine

what does the ± mean here?
what does it mean here? does it mean for example x 10 (meaning TIMES in multiplication?) 85.24.186.196 (talk) 19:12, 29 April 2024 (UTC)

 * It probably meant either "standard deviation" or "standard error". However, this is an encyclopedia entry, not a scientific article, so was not necessary. I deleted these symbols and cleaned up the table a bit. One could even argue that a table of binding affinities is too much in the weeds for an encyclopedia article. But I like it, so will not be advocating for its deletion. Jaredroach (talk) 22:47, 29 April 2024 (UTC)

title: Talk:Fluoxetine