A wildfire or wildland fire is a fire in an area of combustible vegetation occurring in rural areas. Depending on the type of vegetation present, a wildfire can be classified more as a brush fire, desert fire, forest fire, grass fire, hill fire, peat fire, vegetation fire, or veld fire. Fossil charcoal indicates that wildfires began soon after the appearance of terrestrial plants 420 million years ago. Wildfire's occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems' flora and fauna. Earth is an intrinsically flammable planet owing to its cover of carbon-rich vegetation, seasonally dry climates, atmospheric oxygen, widespread lightning and volcanic ignitions. Wildfires can be characterized in terms of the cause of ignition, their physical properties, the combustible material present, the effect of weather on the fire. Wildfires can cause damage to property and human life, although occurring wildfires may have beneficial effects on native vegetation and ecosystems that have evolved with fire.
High-severity wildfire creates complex early seral forest habitat, which has higher species richness and diversity than unburned old forest. Many plant species depend on the effects of fire for reproduction. Wildfires in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have negative ecological effects. Wildfire behavior and severity result from a combination of factors such as available fuels, physical setting, weather. Analyses of historical meteorological data and national fire records in western North America show the primacy of climate in driving large regional fires via wet periods that create substantial fuels, or drought and warming that extend conducive fire weather. Strategies for wildfire prevention and suppression have varied over the years. One common and inexpensive technique is controlled burning: intentionally igniting smaller fires to minimize the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to maintain high species diversity and limit the accumulation of plants and other debris that may serve as fuel.
Wildland fire use is the cheapest and most ecologically appropriate policy for many forests. Fuels may be removed by logging, but fuels treatments and thinning have no effect on severe fire behavior when under extreme weather conditions. Wildfire itself is "the most effective treatment for reducing a fire's rate of spread, fireline intensity, flame length, heat per unit of area", according to Jan Van Wagtendonk, a biologist at the Yellowstone Field Station. Building codes in fire-prone areas require that structures be built of flame-resistant materials and a defensible space be maintained by clearing flammable materials within a prescribed distance from the structure. Three major natural causes of wildfire ignitions exist: dry climate lightning volcanic eruptionThe most common direct human causes of wildfire ignition include arson, discarded cigarettes, power-lines arcs, sparks from equipment. Ignition of wildland fires via contact with hot rifle-bullet fragments is possible under the right conditions.
Wildfires can be started in communities experiencing shifting cultivation, where land is cleared and farmed until the soil loses fertility, slash and burn clearing. Forested areas cleared by logging encourage the dominance of flammable grasses, abandoned logging roads overgrown by vegetation may act as fire corridors. Annual grassland fires in southern Vietnam stem in part from the destruction of forested areas by US military herbicides and mechanical land-clearing and -burning operations during the Vietnam War; the most common cause of wildfires varies throughout the world. In Canada and northwest China, lightning operates as the major source of ignition. In other parts of the world, human involvement is a major contributor. In Africa, Central America, Mexico, New Zealand, South America, Southeast Asia, wildfires can be attributed to human activities such as agriculture, animal husbandry, land-conversion burning. In China and in the Mediterranean Basin, human carelessness is a major cause of wildfires.
In the United States and Australia, the source of wildfires can be traced both to lightning strikes and to human activities. Coal seam fires burn in the thousands around the world, such as those in Burning Mountain, New South Wales, they can flare up unexpectedly and ignite nearby flammable material. The spread of wildfires varies based on the flammable material present, its vertical arrangement and moisture content, weather conditions. Fuel arrangement and density is governed in part by topography, as land shape determines factors such as available sunlight and water for plant growth. Overall, fire types can be characterized by their fuels as follows: Ground fires are fed by subterranean roots and other buried organic matter; this fuel type is susceptible to ignition due to spotting. Ground fires burn by smoldering, can burn for days to months, such as peat fires in Kalimantan and Eastern Sumatra, which resulted from a riceland creation project that unintentionally drained and dried the peat.
Crawling or surface fires are fueled by low-lying vegetation on the forest floor such as leaf and timber litter, debris and low-lying shrubbery. This kind of fire burns at a lower temperature than crown fires and may spread
Vancouver is a coastal seaport city in western Canada, located in the Lower Mainland region of British Columbia. As the most populous city in the province, the 2016 census recorded 631,486 people in the city, up from 603,502 in 2011; the Greater Vancouver area had a population of 2,463,431 in 2016, making it the third-largest metropolitan area in Canada. Vancouver has the highest population density in Canada with over 5,400 people per square kilometre, which makes it the fifth-most densely populated city with over 250,000 residents in North America behind New York City, San Francisco, Mexico City according to the 2011 census. Vancouver is one of the most ethnically and linguistically diverse cities in Canada according to that census. 30% of the city's inhabitants are of Chinese heritage. Vancouver is classed as a Beta global city. Vancouver is named as one of the top five worldwide cities for livability and quality of life, the Economist Intelligence Unit acknowledged it as the first city ranked among the top-ten of the world's most well-living cities for five consecutive years.
Vancouver has hosted many international conferences and events, including the 1954 British Empire and Commonwealth Games, UN Habitat I, Expo 86, the World Police and Fire Games in 1989 and 2009. In 2014, following thirty years in California, the TED conference made Vancouver its indefinite home. Several matches of the 2015 FIFA Women's World Cup were played in Vancouver, including the final at BC Place; the original settlement, named Gastown, grew up on clearcuts on the west edge of the Hastings Mill logging sawmill's property, where a makeshift tavern had been set up on a plank between two stumps and the proprietor, Gassy Jack, persuaded the curious millworkers to build him a tavern, on July 1, 1867. From that first enterprise, other stores and some hotels appeared along the waterfront to the west. Gastown became formally laid out as a registered townsite dubbed Granville, B. I.. As part of the land and political deal whereby the area of the townsite was made the railhead of the Canadian Pacific Railway, it was renamed "Vancouver" and incorporated shortly thereafter as a city, in 1886.
By 1887, the Canadian Pacific transcontinental railway was extended westward to the city to take advantage of its large natural seaport to the Pacific Ocean, which soon became a vital link in a trade route between the Orient / East Asia, Eastern Canada, Europe. As of 2014, Port Metro Vancouver is the third-largest port by tonnage in the Americas, 27th in the world, the busiest and largest in Canada, the most diversified port in North America. While forestry remains its largest industry, Vancouver is well known as an urban centre surrounded by nature, making tourism its second-largest industry. Major film production studios in Vancouver and nearby Burnaby have turned Greater Vancouver and nearby areas into one of the largest film production centres in North America, earning it the nickname "Hollywood North"; the city takes its name from George Vancouver, who explored the inner harbour of Burrard Inlet in 1792 and gave various places British names. The family name "Vancouver" itself originates from the Dutch "Van Coevorden", denoting somebody from the city of Coevorden, Netherlands.
The explorer's ancestors came to England "from Coevorden", the origin of the name that became "Vancouver". Archaeological records indicate that Aboriginal people were living in the "Vancouver" area from 8,000 to 10,000 years ago; the city is located in the traditional and presently unceded territories of the Squamish and Tseil-Waututh peoples of the Coast Salish group. They had villages in various parts of present-day Vancouver, such as Stanley Park, False Creek, Point Grey and near the mouth of the Fraser River. Europeans became acquainted with the area of the future Vancouver when José María Narváez of Spain explored the coast of present-day Point Grey and parts of Burrard Inlet in 1791—although one author contends that Francis Drake may have visited the area in 1579; the explorer and North West Company trader Simon Fraser and his crew became the first-known Europeans to set foot on the site of the present-day city. In 1808, they travelled from the east down the Fraser River as far as Point Grey.
The Fraser Gold Rush of 1858 brought over 25,000 men from California, to nearby New Westminster on the Fraser River, on their way to the Fraser Canyon, bypassing what would become Vancouver. Vancouver is among British Columbia's youngest cities. A sawmill established at Moodyville in 1863, began the city's long relationship with logging, it was followed by mills owned by Captain Edward Stamp on the south shore of the inlet. Stamp, who had begun logging in the Port Alberni area, first attempted to run a mill at Brockton Point, but difficult currents and reefs forced the relocation of the operation in 1867 to a point near the foot of Dunlevy Street; this mill, known as the Hastings Mill, became the nucleus. The mill's central role in the city waned after the arrival of the Canadian Pacific Railway in the 1880s, it remained important to the local economy until it closed in the 1920s. The settlement which came to be called Gastown grew around
Nav Canada is a run, not-for-profit corporation that owns and operates Canada's civil air navigation system. It was established in accordance with the Civil Air Navigation Services Commercialization Act; the company employs 1,900 air traffic controllers, 650 flight service specialists and 700 technologists. It has been responsible for the safe and expeditious flow of air traffic in Canadian airspace since November 1, 1996 when the government transferred the ANS from Transport Canada to Nav Canada; as part of the transfer, or privatization, Nav Canada paid the government CA$1.5 billion. Nav Canada manages 12 million aircraft movements a year for 40,000 customers in over 18 million square kilometres, making it the world’s second-largest air navigation service provider by traffic volume. Nav Canada, which operates independently of any government funding, is headquartered in Ottawa, Ontario, it is only allowed to be funded by service charges to aircraft operators. Nav Canada's operations consist of various sites across the country.
These include: About 1,400 ground-based navigation aids 55 flight service stations 8 flight information centres, one each in: Kamloops – most of British Columbia Edmonton – all of Alberta and northeastern BC Winnipeg – northwestern Ontario, all of Manitoba and Saskatchewan London – most of Ontario North Bay – all of Nunavut and Northwest Territories, most of the Arctic waters Quebec City – all of Quebec, southwestern Labrador, tip of eastern Ontario, northern New Brunswick Halifax – most of New Brunswick, Nova Scotia, Prince Edward Island, most of Newfoundland and Labrador Whitehorse – northwestern British Columbia and all of Yukon 41 control towers 46 radar sites and 15 automatic dependent surveillance-broadcast ground sites 7 Area Control Centres, one each in: Vancouver – Surrey, BC Edmonton – Edmonton International Airport Winnipeg – Winnipeg-James Armstrong Richardson International Airport Toronto Centre – Toronto-Pearson International Airport Montreal Centre – Montreal-Trudeau International Airport Moncton – Riverview, New Brunswick Gander – Gander International Airport North Atlantic Oceanic control centre: Gander ControlNav Canada has three other facilities: National Operations Centre: Ottawa Technical Systems Centre: Ottawa The Nav Centre – 1950 Montreal Road in Cornwall, Ontario As a non-share capital corporation, Nav Canada has no shareholders.
The company is governed by a 15-member board of directors representing the four stakeholder groups that founded Nav Canada. The four stakeholders elect 10 members as follows: These 10 directors elect four independent directors, with no ties to the stakeholder groups; those 14 directors appoint the president and chief executive officer who becomes the 15th board member. This structure ensures that the interests of individual stakeholders do not predominate and no member group could exert undue influence over the remainder of the board. To further ensure that the interests of Nav Canada are served, these board members cannot be active employees or members of airlines, unions, or government; the company was formed on November 1, 1996 when the government sold the country's air navigation services from Transport Canada to the new not-for-profit private entity for CAD$1.5 billion. The company was formed in response to a number of issues with Transport Canada's operation of air traffic control and air navigation facilities.
While TC's safety record and operational staff were rated its infrastructure was old and in need of serious updating at a time of government restraint. This resulted in system delays for airlines and costs that were exceeding the airline ticket tax, a directed tax, supposed to fund the system; the climate of government wage freezes resulted in staff shortages of air traffic controllers that were hard to address within a government department. Having TC as the service provider, the regulator and inspector was a conflict of interest. Pressure from the airlines on the government mounted for a solution to the problem, hurting the air industry's bottom line. A number of solutions were considered, including forming a crown corporation, but rejected in favour of outright privatization, the new company being formed as a non-share-capital not-for-profit, run by a board of directors who were appointed and now elected; the company's revenue is predominately from service fees charged to aircraft operators which amount to about CAD$1.2B annually.
Nav Canada raises revenues from developing and selling technology and related services to other air navigation service providers around the world. It has some smaller sources of income, such as conducting maintenance work for other ANS providers and rentals from the Nav Centre in Cornwall, Ontario. To address the old infrastructure it purchased from the Canadian government the company has carried out projects such as implementing a wide area multilateration system, replacing 95 Instrument Landing System installations with new equipment, new control towers in Toronto and Calgary, modernizing the Vancouver Area Control Centre and building a new logistics centre Nav Canada felt the impact of the late-2000s recession in two ways: losses in its investments in third party sponsored asset-backed commercial paper and falling revenues due to reduced air traffic levels. In the summer of 2007 the company held $368 million in ABCP. On 12 January 2009 final Ontario Superior Court of Justice approval was granted to restructure the third party ABCP notes.
The company expects that the non-credit related fai
A fixed-base operator is an organization granted the right by an airport to operate at the airport and provide aeronautical services such as fueling, tie-down and parking, aircraft rental, aircraft maintenance, flight instruction, similar services. In common practice, an FBO is the primary provider of support services to general aviation operators at a public-use airport and is located either on airport leasehold property or, in rare cases, adjacent to airport leasehold property as a "through the fence operation". In many smaller airports serving general aviation in remote or modest communities, the town itself may provide fuel services and operate a basic FBO facility. Most FBOs doing business at airports of high to moderate traffic volume are non-governmental organizations, i.e. either or publicly held companies. Though the term fixed-base operator originated in the United States, the term is becoming more common in the international aviation industry as business and corporate aviation grows.
The term has not been defined as an international standard, but there have been recent uses of the term in International Civil Aviation Organization publications such as Implementing the Global Aviation Safety Roadmap. After the end of World War I in November 1918, civil aviation in the United States was unregulated and was made up of "barnstormers," who were transient pilots flying inexpensive military surplus aircraft from city to city landing in farm fields on the outskirts of a town because airports were scarce at that time; these traveling aviators offered airplane rides and aerobatic flight demonstrations, they collaborated as "flying circuses" and performed impromptu airshows for the townsfolk, charging whatever the local economic conditions would allow. As a result and early flight instructors moved around with the aircraft and had no established business in any one location. With passage of the Air Commerce Act of 1926 and its resulting requirements for the licensing of pilots, aircraft maintenance requirements, regulations in training standards, the transient nature of civil aviation was curtailed.
The pilots and mechanics who made their living on the road began establishing permanent businesses, termed fixed-base operations, at the growing number of airports appearing throughout the United States as a way to distinguish permanent businesses from the transient businesses common prior to 1926. Fixed-base operators support a wide range of aeronautical activities which may include one or more of the following: Sale of aviation fuel – piston aircraft fuel and/or turbine aircraft fuel Line services for general aviation aircraft Air taxi and air charter operations Scheduled or nonscheduled air carrier services and support services Pilot training Aircraft rental and sightseeing Aircraft sales and service Aircraft storage Repair and Aircraft maintenance. Sale of aircraft parts Aerial photography Crop dusting and aerial applications Aerial advertising and Aerial surveyThough not required, fixed-base operators also provide at least basic auxiliary services to pilots, flight crew, passengers such as restroom facilities, telecommunication services, waiting areas.
General aviation FBOs sometimes provide Courtesy Cars that can be used for free or little cost by flight crews for short trip from the airport and the surrounding city area. Larger and better equipped FBOs may additionally offer food vending and restaurant facilities, ground transportation arrangements taxi/limousine, shuttle van, flight planning and weather information areas, rest lounges and showers, aviation supplies shop, access to in-flight catering, accommodations reservations or concierge services for both crew and passengers through a customer service representative. At medium and large airports, FBOs are affiliated with one of the major aviation fuel suppliers and display the fuel supplier's sign prominently. At smaller airports, the FBO is the airport operator or a flying club. Within the United States, the Federal Aviation Administration regulates some activities that may comprise an FBO such as the authorization or repair stations, flight training, air taxi/air carrier services, but the overarching term "FBO" has no regulatory standards through the federal government.
That said, the FAA has defined an FBO as "a commercial entity providing aeronautical services such as fueling, storage and flight instruction, etc. to the public."The United States Department of Transportation, in cooperation with the FAA, has the duty of establishing minimum standards for commercial aeronautical activities and recommends implementation of these standards by the airport operator or agency referred to as the airport sponsor. The United States FBO Industry is represented nationally by the National Air Transportation Association or NATA, but is partly represented by both the National Business Aviation Association and the Aircraft Owners and Pilots Association; the number of U. S. businesses meeting the minimum criteria as an FBO is 3,138 as of April 2009 according to a survey conducted by Aviation Resource Group International. The number has decreased since the 2006 survey. FBOs are taking some time to grow in the Asian continent, but they have appeared most notably in Hong Kong, Singapore, Kuala Lumpur and the Philippines.
This is due to the immaturity of the private and corporate aviation sector in Asia where there still exist few of these aircraft when compared to the United States and Europe. However sever
Fairbanks is a home rule city and the borough seat of the Fairbanks North Star Borough in the U. S. state of Alaska. Fairbanks is the largest city in the Interior region of Alaska. 2016 estimates put the population of the city proper at 32,751, the population of the Fairbanks North Star Borough at 97,121, making it the second most populous metropolitan area in Alaska. The Metropolitan Statistical Area encompasses all of the Fairbanks North Star Borough and is the northernmost Metropolitan Statistical Area in the United States, located 196 driving miles south of the Arctic Circle. Fairbanks is home to the University of Alaska Fairbanks, the founding campus of the University of Alaska system. Though, as of yet, there is not a known permanent Alaska Native settlement at the site of Fairbanks, Athabascan peoples have used the area for thousands of years. An archaeological site excavated on the grounds of the University of Alaska Fairbanks uncovered a Native camp about 3,500 years old, with older remains found at deeper levels.
From evidence gathered at the site, archaeologists surmise that Native activities in the area were limited to seasonal hunting and fishing as fridge temperatures precluded berry gathering. In addition, archeological sites on the grounds of nearby Fort Wainwright date back well over 10,000 years. Arrowheads excavated from the University of Alaska Fairbanks site matched similar items found in Asia, providing some of the first evidence that humans arrived in North America via the Bering Strait land bridge in deep antiquity. Captain E. T. Barnette founded Fairbanks in August 1901 while headed to Tanacross, where he intended to set up a trading post; the steamboat on which Barnette was a passenger, the Lavelle Young, ran aground while attempting to negotiate shallow water. Barnette, along with his party and supplies, were deposited along the banks of the Chena River 7 miles upstream from its confluence with the Tanana River; the sight of smoke from the steamer's engines caught the attention of gold prospectors working in the hills to the north, most notably an Italian immigrant named Felice Pedroni and his partner Tom Gilmore.
The two met Barnette where he convinced him of the potential of the area. Barnette set up his trading post at the site, still intending to make it to Tanacross. Teams of gold prospectors soon congregated around the newly founded Fairbanks. After some urging by James Wickersham, who moved the seat of the Third Division court from Eagle to Fairbanks, the settlement was named after Charles W. Fairbanks, a Republican senator from Indiana and the twenty-sixth Vice President of the United States, serving under Theodore Roosevelt during his second term. In these early years of settlement, the Tanana Valley was an important agricultural center for Alaska until the establishment of the Matanuska Valley Colonization Project and the town of Palmer in 1935. Agricultural activity still occurs today in the Tanana Valley, but to the southeast of Fairbanks in the communities of Salcha and Delta Junction. During the early days of Fairbanks, its vicinity was a major producer of agricultural goods. What is now the northern reaches of South Fairbanks was the farm of Paul J. Rickert, who came from nearby Chena in 1904 and operated a large farm until his death in 1938.
Farmers Loop Road and Badger Road, loop roads north and east of Fairbanks, were home to major farming activity. Badger Road is named for Harry Markley Badger, an early resident of Fairbanks who established a farm along the road and became known as "the Strawberry King". Ballaine and McGrath Roads, side roads of Farmers Loop Road, were named for prominent local farmers, whose farms were in the immediate vicinity of their respective namesake roads. Despite early efforts by the Alaska Loyal League, the Tanana Valley Agriculture Association and William Fentress Thompson, the editor-publisher of the Fairbanks Daily News-Miner, to encourage food production, agriculture in the area was never able to support the population, although it came close in the 1920s; the construction of Ladd Army Airfield starting in 1939, part of a larger effort by the federal government during the New Deal and World War II to install major infrastructure in the territory for the first time, fostered an economic and population boom in Fairbanks which extended beyond the end of the war.
In the 1940s the Canol pipeline extended north from Whitehorse for a few years. The Haines - Fairbanks 626 mile long 8" petroleum products pipeline was constructed during the period 1953-55; the presence of the U. S. military has remained strong in Fairbanks. Ladd became Fort Wainwright in 1960. Fairbanks suffered from several floods in its first seven decades, whether from ice jams during spring breakup or heavy rainfall; the first bridge crossing the Chena River, a wooden structure built in 1904 to extend Turner Street northward to connect with the wagon roads leading to the gold mining camps washed out before a permanent bridge was constructed at Cushman Street in 1917 by the Alaska Road Commission. On August 14, 1967, after record rainfall upstream, the Chena began to surge over its banks, flooding the entire town of Fairbanks overnight; this disaster led to the creation of the Chena River Lakes Flood Control Project, which built and operates the 50-foot-high Moose Creek Dam in the Chena River and accompanying 8-mile-long spillway.
The project was designed to prevent a repetition of the 1967 flood by being able to
Airline hubs or hub airports are used by one or more airlines to concentrate passenger traffic and flight operations at a given airport. They serve, it is part of the hub-and-spoke system. An airline operates flights from several non-hub cities to the hub airport, passengers traveling between spoke cities need to connect through the hub; this paradigm creates economies of scale that allow an airline to serve city-pairs that could otherwise not be economically served on a non-stop basis. This system contrasts with the point-to-point model, in which there are no hubs and nonstop flights are instead offered between spoke cities. Hub airports serve origin and destination traffic. In the airline industry, a focus city is a destination from which an airline operates limited point-to-point routes. Ergo, a focus city caters to the local market rather than to connecting passengers. However, with the term's expanded usage, a focus city may function as a small-scale or total hub. Allegiant Air, JetBlue and Southwest Airlines are examples of US-based airlines that consider some of their focus cities run like a hub.
The hub-and-spoke system allows an airline to serve fewer routes, so fewer aircraft are needed. The system increases passenger loads. However, the system is costly. Additional employees and facilities are needed to cater to connecting passengers. To serve spoke cities of varying populations and demand, an airline requires several aircraft types, specific training and equipment are necessary for each type. In addition, airlines may experience capacity constraints. For the passenger, the hub-and-spoke system offers one-stop air service to a wide array of destinations. However, it requires having to make connections en route to their final destination, which increases travel time. Additionally, airlines can come to monopolise their hubs, allowing them to increase fares as passengers have no alternative. Airlines may operate banks of flights at their hubs, in which several flights arrive and depart within short periods of time; the banks may be known as "peaks" of activity at the hubs and the non-banks as "valleys".
Banking allows for short connection times for passengers. However, an airline must assemble a large number of resources to cater to the influx of flights during a bank, having several aircraft on the ground at the same time can lead to congestion and delays. In addition, banking could result in inefficient aircraft utilisation, with aircraft waiting at spoke cities for the next bank. Instead, some airlines have debanked their hubs, introducing a "rolling hub" in which flight arrivals and departures are spread throughout the day; this phenomenon is known as "depeaking". While costs may decrease, connection times are longer at a rolling hub. American Airlines was the first to depeak its hubs, trying to improve profitability following the September 11 attacks, it rebanked its hubs in 2015, feeling the gain in connecting passengers would outweigh the rise in costs. The hub-and-spoke system is used by some cargo airlines. FedEx Express established its main hub in Memphis in 1973, prior to the deregulation of the air cargo industry in the United States.
The system has created an efficient delivery system for the airline. Other airlines that use this system include UPS Airlines, TNT Airways, Cargolux and DHL Aviation, which operate their primary hubs at Louisville, Liège, Luxembourg and Leipzig respectively. Although the term focus city is used to refer to an airport from which an airline operates limited point-to-point routes, its usage has loosely expanded to refer to a small-scale hub as well. For example, JetBlue's New York–JFK focus city runs like a hub, although in reality it is still deemed as a focus city. A fortress hub exists when an airline controls a significant majority of the market at one of its hubs. Competition is difficult at fortress hubs. Examples include Delta hubs at Atlanta, Salt Lake City and Minneapolis–Saint Paul. Flag carriers have enjoyed similar dominance at the main international airport of their countries and some still do. Examples include Lufthansa at Frankfurt Airport, Air Canada at Toronto Pearson Airport, Alitalia at Rome Fiumicino Airport, KLM at Amsterdam Airport Schiphol, Garuda Indonesia at Soekarno-Hatta International Airport, British Airways at London Heathrow, Air China at Beijing Capital Airport, Iberia at Madrid-Barajas Airport and Air France at Paris Orly and Charles de Gaulle Airports.
A primary hub is the main hub for an airline. However, as an airline expands operations at its primary hub to the point that it experiences capacity limitations, it may elect to open secondary hubs. Examples of such hubs are Turkish Airlines' Istanbul–Sabiha Gökçen hub, British Airways' hub at London-Gatwick, Air India's hub at Mumbai and Lufthansa's hub at Munich. By operating multiple hubs, airlines can expand their geographic reach, they can better serve spoke–spoke markets, providing more itineraries with connections at different hubs. A given hub's capacity may become exhausted or capacity shortages may occur during peak periods of the day, at which point airlines may be compelled to shift traffic to a reliever hub. A reliever hub has the potential to serve several functions for an airline: it can bypass the congested hub, it can absorb
A weather vane, wind vane, or weathercock is an instrument for showing the direction of the wind. It is used as an architectural ornament to the highest point of a building; the word vane comes from the Old English word fana meaning "flag". Although functional, weather vanes are decorative featuring the traditional cockerel design with letters indicating the points of the compass. Other common motifs include ships and horses. Not all weather vanes have pointers; when the wind is sufficiently strong, the head of the arrow or cockerel will indicate the direction from which the wind is blowing. The weather vane was independently invented in ancient China and Greece around the same time during the 2nd century BCE; the earliest written reference to a weather vane appears in the Huainanzi, a weather vane was fitted on top of the Tower of the Winds in Athens. The oldest textual reference to a weather vane comes from the Chinese Huainanzi dating from around 139 BC, which describes a "wind-observing fan".
The Tower of the Winds on the ancient Greek agora in Athens once bore on its roof a wind vane in the form of a bronze Triton holding a rod in his outstretched hand, rotating as the wind changed direction. Below this was a frieze adorned with the eight Greek wind deities; the eight-metre-high structure featured sundials, a water clock inside. It dates from around 50 BC. Military documents from the Three Kingdoms period of China refer to the weather vane as "five ounces", named after the weight of its materials. By the 3rd century, Chinese weather vanes were shaped like birds and took the name of "wind-indicating bird"; the Sanfu huangtu, a 3rd-century book written by Miao Changyan about the palaces at Chang'an, describes a bird-shaped wind vane situated on a tower roof, also an anemometer: The Han'Ling Tai' was eight li north-west of Chang'an. It was called'Ling Tai' because it was intended for observations of the Yin and the Yang and the changes occurring in the celestial bodies, but in the Han it began to be called Qing Tai.
Guo Yuansheng, in his Shu Zheng Ji, says that south of the palaces there was a Ling Tai, fifteen ren high, upon the top of, the armillary sphere made by Zhang Heng. There was a wind-indicating bronze bird, moved by the wind. There was a bronze gnomon 8 feet high, with a 13 feet long and 1 foot 2 inches broad. According to an inscription, this was set up in the 4th year of the Taichu reign-period; the oldest surviving weather vane with the shape of a rooster is the Gallo di Ramperto, made in 820 AD and now preserved in the Museo di Santa Giulia in Brescia, Lombardy. Pope Leo IV had a cock placed on the Old St. Peter's old Constantinian basilica. Pope Gregory I said that the cock "was the most suitable emblem of Christianity", being "the emblem of St Peter", a reference to Luke 22:34 in which Jesus predicts that Peter will deny him three times before the rooster crows; as a result of this, the cock began to be used as a weather vane on church steeples, in the 9th century Pope Nicholas I ordered the figure to be placed on every church steeple.
The Bayeux Tapestry of the 1070s depicts a man installing a cock on Westminster Abbey. One alternative theory about the origin of weathercocks on church steeples is that it was an emblem of the vigilance of the clergy calling the people to prayer. Another theory says that the cock was not a Christian symbol but an emblem of the sun derived from the Goths. A few churches used weather vanes in the shape of the emblems of their patron saints; the City of London has two surviving examples. The weather vane of St Peter upon Cornhill is not a key. Early weather vanes had ornamental pointers, but modern wind vanes are simple arrows that dispense with the directionals because the instrument is connected to a remote reading station. An early example of this was installed in the Royal Navy's Admiralty building in London – the vane on the roof was mechanically linked to a large dial in the boardroom so senior officers were always aware of the wind direction when they met. Modern aerovanes combine the directional vane with an anemometer.
Co-locating both instruments provides a coordinated readout. According to the Guinness World Records, the world's largest weather vane is a Tío Pepe sherry advertisement located in Jerez, Spain; the city of Montague, Michigan claims to have the largest standard-design weather vane, being a ship and arrow which measures 48 feet tall, with an arrow 26 feet long. A challenger for the title of world's largest weather vane is located in Yukon; the weather vane is a retired Douglas DC-3 CF-CPY atop a swiveling support. Located at the Yukon Transportation Museum beside Whitehorse International Airport, the weather vane is used by pilots to determine wind direction, used as a landmark by tourists and enjoyed by locals; the weather vane only requires a 5 knot wind to rotate. A challenger for the worlds tallest weather vane is located in Alberta; the classic weather vane that reaches to 50 feet is topped by a 1942 Case Model D Tractor. This landmark is located at the Canadian Tractor Museum; the term "weathervane" is a slang word for a politician who has frequent changes of opinion.
The National Assembly of Quebec has banned use of this slang term as a sl