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AVIATION
Aviation refers to flying using aircraft, machines designed by humans for atmospheric flight. More generally, the term also describes the activities, industries, and regulatory bodies associated with aircraft.
History
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There are records of early, short-distance glider flights from the 10th and 11th centuries, and possibly earlier human-carrying kites from China, but practical human aviation (trips lasting more than a few seconds) began on November 21, 1783 with the first untethered human flight in a hot air balloon designed by the Montgolfier brothers. A little over a century later, on December 17, 1903, the Wright brothers flew the first successful powered, heavier-than-air flight, though their aircraft was impractical to fly for more than a short distance, due to control problems. The widespread adoption of ailerons made aircraft much easier to manage, and only a decade later, at the start of World War I, heavier-than-air powered aircraft had become practical for reconnaissance, artillery spotting, and even attacks against ground positions.
Between the wars, aircraft grew larger and more reliable, and began to be used to transport people and cargo. Initially, many people believed that airships (also called dirigibles) were the most practical way of transporting passengers long distances by air. In the 1930s, however, the Douglas DC-3 became the first airliner that was profitable carrying passengers exclusively, starting the modern era of passenger airline service, and around the same time, the Hindenburg disaster of 1937 destroyed the popularity of airships for general passenger use (though there are periodic initiatives to revive them). By the beginning of World War II, many towns and cities had built airports, and there were a large number of qualified pilots available. The war brought many innovations to aviation, including the first jet aircraft and the first liquid-fueled rockets.
After the war, especially in North America, there was a boom in general aviation, both private and commercial, as thousands of pilots were released from military service and many inexpensive war-surplus transport and training aircraft were available. Small aircraft manufacturers such as Cessna, Piper, and Beechcraft expanded production to provide small aircraft for the new middle class market.
By the 1950s, the development of civil jets grew, beginning with the de Havilland Comet, though the first widely-used passenger jet was the Boeing 707. At the same time, turboprop propulsion began to appear for smaller commuter planes, making it possible to serve small-volume routes in a much wider range of weather conditions.
Yuri Gagarin was the first human to travel to space on April 12, 1961 while the Apollo 11 crew first were the first to set foot on the moon on July 21, 1969.
Since the 1960s, composite airframes and quieter, more efficient engines have become available, but the most important innovations have taken place in instrumentation and control. The arrival of solid-state electronics, the Global Positioning System, satellite communications, and increasingly small and powerful computers and LED displays, have dramatically changed the cockpits of airliners and, increasingly, of smaller aircraft as well. Pilots can navigate much more accurately and view terrain, obstructions, and other nearby aircraft on a map or through synthetic vision, even at night or in low visibility.
On June 21, 2004, SpaceShipOne became the first privately-funded aircraft to make a spaceflight, opening the possibility of an aviation market outside the earth's atmosphere.
Civil aviation
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Civil aviation includes all non-military flying, both general aviation and scheduled air transport.
Commercial transport
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While there were many more in the past, there are currently only five major manufacturers of transport aircraft:
Boeing, Airbus, and Tupolev concentrate on larger airliners, while Bombardier and Embraer concentrate on commuter aircraft.
Until the 1970s, most major airlines were flag carriers, sponsored by their governments and heavily protected from competition. Since then, various open skies agreements have resulted in increased competition and choice for consumers, coupled with falling prices for airlines. The combination of high fuel prices, low fares, high salaries, and crises such as the September 11, 2001 attacks and the SARS epidemic have driven many older airlines to government-bailouts, bankruptcy or mergers. At the same time, low-cost carriers such as Ryanair and Southwest have flourished.
A special commercial air transport were the air ferries carrying cars over the British cannel.
General Aviation
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General aviation includes any flight that is not military and does not fly on a regular schedule, ranging from a recreational flight in a hang glider to a non-scheduled cargo flight in a Boeing 747. The majority of flights on any day will fall into this category.
Because of the huge range of activities, it is difficult to cover general aviation with a simple description — general aviation may include business flights, private aviation, flight training, parachuting, gliding, air ambulance, crop dusting, charter flights, traffic reporting, police air patrols, forest fire flighting, and many other types of flying.
Each country regulates aviation differently, but typically, general aviation falls under several different types of regulations depending on whether it is private or commercial and on the type of equipment involved.
Many small aircraft manufacturers, including Cessna, Piper, Mooney, Cirrus Design, Raytheon, and others serve the general aviation market, with a focus on private aviation and flight training. The most important recent developments for small aircraft have been the introduction of advanced avionics (including GPS) that were formerly found only in large airliners, and the introduction of composite materials to make small aircraft lighter and faster.
Military aviation
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The Lockheed SR-71 was remarkably advanced for its time and remains unsurpassed in many areas of performance.
Simple airships were used as surveillance aircraft as early as the 18th century. Over the years, military aircraft have been built to meet ever increasing capability requirements. Manufacturers of military aircraft compete for contracts to supply their government's arsenal. Aircraft are selected based on factors like cost, performance, and the speed of production.
Types of military aircraft
Air Traffic Control (ATC)
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Air traffic control (ATC) involves humans (typically on the ground) who communicate with aircraft to help maintain separation — that is, they ensure that aircraft are far enough apart horizontally or vertically that there is no risk of collision. Controllers may co-ordinate position reports provided by pilots, or in high traffic areas (such as the United States) they may use RADAR to see aircraft positions.
While the exact terminology varies from country to country, there are generally three different types of ATC:
- control towers (including tower, ground control, clearance delivery, and other services), which control aircraft within a small distance (typically 10-15 km horizontal, and 1,000 m vertical) of an airport.
- terminal controllers, who control aircraft in a wider area (typically 50-80 km) around busy airports
- centre controllers, who control aircraft enroute between airports
ATC is especially important for aircraft flying under Instrument flight rules (IFR), where they may be in weather conditions that do not allow the pilots to see other aircraft. However, in very high-traffic areas, especially near major airports, aircraft flying under Visual flight rules (VFR) are also required to follow instructions from ATC.
In addition to separation from other aircraft, ATC may provide weather advisories, terrain separation, navigation assistance, and other services to pilots, depending on their workload.
It is important to note that ATC does not control all flights. The majority of VFR flights in North America are not required to talk to ATC at all (unless they're passing through a busy terminal area or using a major airport), and in many areas, such as northern Canada, ATC services are not available even for IFR flights at lower altitudes.
See also
External links
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