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80-444: In international aviation , SELCAL or SelCal is a selective-calling radio system that can alert an aircraft's crew that a ground radio station wishes to communicate with the aircraft . SELCAL uses a ground-based encoder and radio transmitter to broadcast an audio signal that is picked up by a decoder and radio receiver on an aircraft. The use of SELCAL allows an aircraft crew to be notified of incoming communications even when

160-402: A buoyant force that does not require lateral movement through the surrounding air mass to effect a lifting force. By contrast, aerodynes primarily use aerodynamic lift , which requires the lateral movement of at least some part of the aircraft through the surrounding air mass. Some things that fly do not generate propulsive thrust through the air, for example, the flying squirrel . This

240-451: A rocket launch , which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called astrodynamics . Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry , and others reach

320-412: A SELCAL encoder. The encoder converts the four-letter code into four designated audio tones. The radio operator's transmitter then broadcasts the audio tones on the aircraft's company radio frequency channel in sequence: the first pair of tones are transmitted simultaneously, lasting about one second; a silence of about 0.2 seconds; followed by the second pair of tones, lasting about one second. The code

400-583: A busy terminal area or using a major airport), and in many areas, such as northern Canada and low altitude in northern Scotland, air traffic control services are not available even for IFR flights at lower altitudes. Like all activities involving combustion , operating powered aircraft (from airliners to hot air balloons) releases soot and other pollutants into the atmosphere. Greenhouse gases such as carbon dioxide (CO 2 ) are also produced. In addition, there are environmental impacts specific to aviation: for instance, Another environmental impact of aviation

480-507: A civil aviation authority must approve an aircraft suitable for safe flight operations. MRO firms are responsible for this process, thoroughly checking and documenting all components' repairs while tracking mechanical, propulsion, and electronic parts. Aviation regulators oversee maintenance practices in the country of aircraft registration, manufacture, or current location. All aircraft maintenance activities must adhere to international regulations that mandate standards. An aviation accident

560-456: A feat made possible by their invention of three-axis control and in-house development of an engine with a sufficient power-to-weight ratio . 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. Aircraft began to transport people and cargo as designs grew larger and more reliable. The Wright brothers took aloft

640-512: A few hundred miles, was diminishing as airplane design advanced. The "Golden Age" of the airships ended on May 6, 1937. That year the Hindenburg caught fire, killing 36 people. The cause of the Hindenburg accident was initially blamed on the use of hydrogen instead of helium as the lift gas. An internal investigation by the manufacturer revealed that the coating used in the material covering the frame

720-630: A flying fish was 45 seconds. Most birds fly ( see bird flight ), with some exceptions. The largest birds, the ostrich and the emu , are earthbound flightless birds , as were the now-extinct dodos and the Phorusrhacids , which were the dominant predators of South America in the Cenozoic era. The non-flying penguins have wings adapted for use under water and use the same wing movements for swimming that most other birds use for flight. Most small flightless birds are native to small islands, and lead

800-439: A given pair are written or transmitted in alphabetical order (e.g., AB-CD is an allowable distinct SELCAL code, as is CD-AB , but CD-BA is not). A given letter can be used only once in a SELCAL code; letters may not be repeated (e.g. AB-CD is allowable, but AA-BC and AB-BC are not). Each letter designates a specific audio tone frequency. The rules for SELCAL code assignment, with sixteen available letters/tones, limit

880-427: A heavier aircraft gliding at a higher airspeed will arrive at the same touchdown point in a shorter time. Air pressure acting up against an object in air is greater than the pressure above pushing down. The buoyancy, in both cases, is equal to the weight of fluid displaced - Archimedes' principle holds for air just as it does for water. A cubic meter of air at ordinary atmospheric pressure and room temperature has

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960-564: A lifestyle where flight would offer little advantage. Among living animals that fly, the wandering albatross has the greatest wingspan, up to 3.5 meters (11 feet); the great bustard has the greatest weight, topping at 21 kilograms (46 pounds). Most species of insects can fly as adults. Insect flight makes use of either of two basic aerodynamic models: creating a leading edge vortex, found in most insects, and using clap and fling , found in very small insects such as thrips . Many species of spiders , spider mites and lepidoptera use

1040-411: A mass of about 1.2 kilograms, so its weight is about 12 newtons . Therefore, any 1-cubic-meter object in air is buoyed up with a force of 12 newtons. If the mass of the 1-cubic-meter object is greater than 1.2 kilograms (so that its weight is greater than 12 newtons), it falls to the ground when released. If an object of this size has a mass less than 1.2 kilograms, it rises in the air. Any object that has

1120-601: A mass that is less than the mass of an equal volume of air will rise in air - in other words, any object less dense than air will rise. Thrust-to-weight ratio is, as its name suggests, the ratio of instantaneous thrust to weight (where weight means weight at the Earth 's standard acceleration g 0 {\displaystyle g_{0}} ). It is a dimensionless parameter characteristic of rockets and other jet engines and of vehicles propelled by such engines (typically space launch vehicles and jet aircraft ). If

1200-470: A pair of flat gliding surfaces. "Flying" snakes also use mobile ribs to flatten their body into an aerodynamic shape, with a back and forth motion much the same as they use on the ground. Flying fish can glide using enlarged wing-like fins, and have been observed soaring for hundreds of meters. It is thought that this ability was chosen by natural selection because it was an effective means of escape from underwater predators. The longest recorded flight of

1280-534: A planetary or lunar surface for landing or impact. In 2018, researchers at Massachusetts Institute of Technology (MIT) managed to fly an aeroplane with no moving parts, powered by an " ionic wind" also known as electroaerodynamic thrust. Many human cultures have built devices that fly, from the earliest projectiles such as stones and spears, the boomerang in Australia , the hot air Kongming lantern , and kites . George Cayley studied flight scientifically in

1360-626: A reality in the 20th century following theoretical and practical breakthroughs by Konstantin Tsiolkovsky and Robert H. Goddard . The first orbital spaceflight was in 1957, and Yuri Gagarin was carried aboard the first crewed orbital spaceflight in 1961. There are different approaches to flight. If an object has a lower density than air, then it is buoyant and is able to float in the air without expending energy. A heavier than air craft, known as an aerodyne , includes flighted animals and insects, fixed-wing aircraft and rotorcraft . Because

1440-455: A retarding force called drag. Because lift and drag are both aerodynamic forces, the ratio of lift to drag is an indication of the aerodynamic efficiency of the airplane. The lift to drag ratio is the L/D ratio, pronounced "L over D ratio." An airplane has a high L/D ratio if it produces a large amount of lift or a small amount of drag. The lift/drag ratio is determined by dividing the lift coefficient by

1520-465: A technique called ballooning to ride air currents such as thermals , by exposing their gossamer threads which gets lifted by wind and atmospheric electric fields . Mechanical flight is the use of a machine to fly. These machines include aircraft such as airplanes , gliders , helicopters , autogyros , airships , balloons , ornithopters as well as spacecraft . Gliders are capable of unpowered flight. Another form of mechanical flight

1600-803: Is noise pollution , mainly caused by aircraft taking off and landing. Sonic booms were a problem with supersonic aircraft such as the Concorde . [REDACTED]  This article incorporates text by Wirths, Oliver; Tóth,Zsófia; Diaz Ruiz, Carlos available under the CC BY 4.0 license. Flight Many things can fly, from animal aviators such as birds , bats and insects , to natural gliders/parachuters such as patagial animals, anemochorous seeds and ballistospores , to human inventions like aircraft ( airplanes , helicopters , airships , balloons , etc.) and rockets which may propel spacecraft and spaceplanes . The engineering aspects of flight are

1680-418: Is perpendicular to the flow direction. Aerodynamic lift results when the wing causes the surrounding air to be deflected - the air then causes a force on the wing in the opposite direction, in accordance with Newton's third law of motion . Lift is commonly associated with the wing of an aircraft , although lift is also generated by rotors on rotorcraft (which are effectively rotating wings, performing

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1760-509: Is a firm that ensures airworthiness or air transport. According to a 2024 article, "maintenance (M) involves inspecting, cleaning, oiling, and changing aircraft parts after a certain number of flight hours. Repair (R) is restoring the original function of parts and components. Overhaul (O) refers to extensive maintenance, the complete refurbishment of the aircraft, and upgrades in avionics, which can take several weeks to complete." Airlines are legally obligated to certify airworthiness, meaning that

1840-439: Is a system that remains aloft primarily through the use of buoyancy to give an aircraft the same overall density as air. Aerostats include free balloons , airships , and moored balloons . An aerostat's main structural component is its envelope , a lightweight skin that encloses a volume of lifting gas to provide buoyancy , to which other components are attached. Aerostats are so named because they use "aerostatic" lift,

1920-414: Is common practice for crews to keep the radio volume low unless the radio is immediately needed. A SELCAL notification activates a signal to the crew that they are about to receive a voice transmission, so that the crew has time to raise the volume. An individual aircraft has its own assigned SELCAL code. To initiate a SELCAL transmission, a ground station radio operator enters an aircraft's SELCAL code into

2000-452: Is defined by the Convention on International Civil Aviation Annex 13 as an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight until such time as all such persons have disembarked, in which a person is fatally or seriously injured, the aircraft sustains damage or structural failure or the aircraft

2080-404: Is equal to the drag D divided by the (density r times half the velocity V squared times the reference area A). [Cd = D / (A * .5 * r * V^2)] Lift-to-drag ratios for practical aircraft vary from about 4:1 for vehicles and birds with relatively short wings, up to 60:1 or more for vehicles with very long wings, such as gliders. A greater angle of attack relative to the forward movement also increases

2160-752: Is especially important for aircraft flying under instrument flight rules (IFR), when 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. ATC do not control all flights. The majority of VFR (Visual Flight Rules) flights in North America are not required to contact ATC (unless they are passing through

2240-413: Is flight faster than the speed of sound . Supersonic flight is associated with the formation of shock waves that form a sonic boom that can be heard from the ground, and is frequently startling. The creation of this shockwave requires a significant amount of energy; because of this, supersonic flight is generally less efficient than subsonic flight at about 85% of the speed of sound. Hypersonic flight

2320-490: Is missing or is completely inaccessible. An accident in which the damage to the aircraft is such that it must be written off, or in which the plane is destroyed, is called a hull loss accident . The first fatal aviation accident occurred in a Wright Model A aircraft at Fort Myer, Virginia, US , on September 17, 1908, resulting in injury to the pilot, Orville Wright , and death of the passenger, Signal Corps Lieutenant Thomas Selfridge . The worst aviation accident in history

2400-440: Is para-sailing, where a parachute-like object is pulled by a boat. In an airplane, lift is created by the wings; the shape of the wings of the airplane are designed specially for the type of flight desired. There are different types of wings: tempered, semi-tempered, sweptback, rectangular and elliptical. An aircraft wing is sometimes called an airfoil , which is a device that creates lift when air flows across it. Supersonic flight

2480-455: Is private or commercial and on the type of equipment involved. Many small aircraft manufacturers serve the general aviation market, with a focus on private aviation and flight training. The most important recent developments for small aircraft (which form the bulk of the GA fleet) have been the introduction of advanced avionics (including GPS ) that were formerly found only in large airliners , and

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2560-450: Is pushed in the direction opposite to flight. This can be done in several ways including by the spinning blades of a propeller , or a rotating fan pushing air out from the back of a jet engine , or by ejecting hot gases from a rocket engine . The forward thrust is proportional to the mass of the airstream multiplied by the difference in velocity of the airstream. Reverse thrust can be generated to aid braking after landing by reversing

2640-462: Is received by any aircraft receiver monitoring the radio frequency on which the SELCAL code is broadcast. A SELCAL decoder is connected to each aircraft's radio receiver. When a SELCAL decoder on an aircraft receives a signal containing its own assigned SELCAL code, it alerts the aircraft's crew by sounding a chime, activating a light, or both. The crew next turns up the volume on the aircraft radio to hear

2720-418: Is started after October 2018 under evaluation to increase the number of possible allowable codes. Aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. Aircraft includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air aircraft such as hot air balloons and airships . Aviation began in

2800-475: Is technically assigned to the owner-operator of the aircraft rather than the aircraft itself; if an aircraft is sold, the new owners-operators must apply for a new code. The code is a sequence of four letters, written or transmitted as an ordered two sets of two letters each (e.g. AB-CD ). The letters are chosen from a subset of the Latin script comprising A through S , excluding I , N and O . The letters within

2880-648: Is termed ballistic flight . Examples include balls , arrows , bullets , fireworks etc. Essentially an extreme form of ballistic flight, spaceflight is the use of space technology to achieve the flight of spacecraft into and through outer space . Examples include ballistic missiles , orbital spaceflight , etc. Spaceflight is used in space exploration , and also in commercial activities like space tourism and satellite telecommunications . Additional non-commercial uses of spaceflight include space observatories , reconnaissance satellites and other Earth observation satellites . A spaceflight typically begins with

2960-493: Is termed gliding . Some other things can exploit rising air to climb such as raptors (when gliding) and man-made sailplane gliders . This is termed soaring . However most other birds and all powered aircraft need a source of propulsion to climb. This is termed powered flight. The only groups of living things that use powered flight are birds , insects , and bats , while many groups have evolved gliding. The extinct pterosaurs , an order of reptiles contemporaneous with

3040-455: Is very high speed flight where the heat generated by the compression of the air due to the motion through the air causes chemical changes to the air. Hypersonic flight is achieved primarily by reentering spacecraft such as the Space Shuttle and Soyuz . Some things generate little or no lift and move only or mostly under the action of momentum, gravity, air drag and in some cases thrust. This

3120-895: The September 11 attacks and the SARS pandemic have driven many older airlines to government-bailouts, bankruptcy or mergers. At the same time, low-cost carriers such as Ryanair , Southwest and WestJet have flourished. General aviation includes all non-scheduled civil flying, both private and commercial . General aviation may include business flights, air charter , private aviation, flight training, ballooning , paragliding , parachuting , gliding , hang gliding , aerial photography , foot-launched powered hang gliders , air ambulance, crop dusting, charter flights, traffic reporting , police air patrols and forest fire fighting. Each country regulates aviation differently, but general aviation usually falls under different regulations depending on whether it

3200-529: The dinosaurs , were also very successful flying animals, and there were apparently some flying dinosaurs (see Flying and gliding animals#Non-avian dinosaurs ). Each of these groups' wings evolved independently , with insects the first animal group to evolve flight. The wings of the flying vertebrate groups are all based on the forelimbs, but differ significantly in structure; insect wings are hypothesized to be highly modified versions of structures that form gills in most other groups of arthropods . Bats are

3280-482: The thrust-to-weight ratio is greater than the local gravity strength (expressed in g s), then flight can occur without any forward motion or any aerodynamic lift being required. If the thrust-to-weight ratio times the lift-to-drag ratio is greater than local gravity then takeoff using aerodynamic lift is possible. Flight dynamics is the science of air and space vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are

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3360-522: The 18th century with the development of the hot air balloon , an apparatus capable of atmospheric displacement through buoyancy . Some of the most significant advancements in aviation technology came with the controlled gliding flying of Otto Lilienthal in 1896; then a large step in significance came with the construction of the first powered airplane by the Wright brothers in the early 1900s. Since that time, aviation has been technologically revolutionized by

3440-535: The 1960s composite material airframes and quieter, more efficient engines have become available, and Concorde provided supersonic passenger service for more than two decades, but the most important lasting 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

3520-719: The Earth's atmosphere. Meanwhile, the need to decarbonize the aviation industry to face the climate crisis has increased research into aircraft powered by alternative fuels, such as ethanol , electricity , hydrogen , and even solar energy , with flying prototypes becoming more common. Civil aviation includes all non-military flying, both general aviation and scheduled air transport . There are five major manufacturers of civil transport aircraft (in alphabetical order): Boeing, Airbus, Ilyushin and Tupolev concentrate on wide-body and narrow-body jet airliners , while Bombardier, Embraer and Sukhoi concentrate on regional airliners . Large networks of specialized parts suppliers from around

3600-522: The French War ministry. The report on the trials was not publicized until 1910, as they had been a military secret. In November 1906, Ader claimed to have made a successful flight on October 14, 1897, achieving an "uninterrupted flight" of around 300 metres (980 feet). Although widely believed at the time, these claims were later discredited. The Wright brothers made the first successful powered, controlled and sustained airplane flight on December 17, 1903,

3680-524: The Hindenburg was the first to be captured on newsreel. In 1799, Sir George Cayley set forth the concept of the modern airplane as a fixed-wing flying machine with separate systems for lift, propulsion, and control. Otto Lilienthal was the first person to make well-documented, repeated, successful flights with gliders , therefore making the idea of " heavier than air " a reality. Newspapers and magazines published photographs of Lilienthal gliding, favorably influencing public and scientific opinion about

3760-659: The United States) they may use radar to see aircraft positions. Becoming an air traffic controller in the United States typically requires an associate or bachelor's degree from the Air Traffic Collegiate Training Initiative. The FAA also requires extensive training, along with medical examinations and background checks. Some controllers are required to work weekend, night, and holiday shifts. There are generally four different types of ATC: ATC

3840-403: The aircraft's radio has been muted. Thus, crewmembers need not devote their attention to continuous radio listening. SELCAL operates on the high frequency (HF) or very high frequency (VHF) radio frequency bands used for aircraft communications. HF radio often has extremely high levels of background noise and can be difficult or distracting to listen to for long periods of time. As a result, it

3920-601: The angles of rotation in three dimensions about the vehicle's center of mass , known as pitch , roll and yaw (See Tait-Bryan rotations for an explanation). The control of these dimensions can involve a horizontal stabilizer (i.e. "a tail"), ailerons and other movable aerodynamic devices which control angular stability i.e. flight attitude (which in turn affects altitude , heading ). Wings are often angled slightly upwards- they have "positive dihedral angle " which gives inherent roll stabilization. To create thrust so as to be able to gain height, and to push through

4000-400: The car stable on the road. For a solid object moving through a fluid, the drag is the component of the net aerodynamic or hydrodynamic force acting opposite to the direction of the movement. Therefore, drag opposes the motion of the object, and in a powered vehicle it must be overcome by thrust . The process which creates lift also causes some drag. Aerodynamic lift is created by

4080-418: 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 capable of leaving

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4160-486: The craft is heavier than air, it must generate lift to overcome its weight . The wind resistance caused by the craft moving through the air is called drag and is overcome by propulsive thrust except in the case of gliding . Some vehicles also use thrust in the place of lift; for example rockets and Harrier jump jets . Forces relevant to flight are These forces must be balanced for stable flight to occur. A fixed-wing aircraft generates forward thrust when air

4240-443: The drag coefficient, CL/CD. The lift coefficient Cl is equal to the lift L divided by the (density r times half the velocity V squared times the wing area A). [Cl = L / (A * .5 * r * V^2)] The lift coefficient is also affected by the compressibility of the air, which is much greater at higher speeds, so velocity V is not a linear function. Compressibility is also affected by the shape of the aircraft surfaces. The drag coefficient Cd

4320-411: The extent of deflection, and thus generates extra lift. However a greater angle of attack also generates extra drag. Lift/drag ratio also determines the glide ratio and gliding range. Since the glide ratio is based only on the relationship of the aerodynamics forces acting on the aircraft, aircraft weight will not affect it. The only effect weight has is to vary the time that the aircraft will glide for –

4400-433: The first jet aircraft and the first liquid-fueled rockets . After World War II, 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 became available. Manufacturers such as Cessna , Piper , and Beechcraft expanded production to provide light aircraft for

4480-619: The first aircraft to transport passengers and cargo over great distances. The best known aircraft of this type were manufactured by the German Zeppelin company. The most successful Zeppelin was the Graf Zeppelin . It flew over one million miles, including an around-the-world flight in August 1929. However, the dominance of the Zeppelins over the airplanes of that period, which had a range of only

4560-410: The first half of the 19th century, and in the second half of the 19th century Otto Lilienthal made over 200 gliding flights and was also one of the first to understand flight scientifically. His work was replicated and extended by the Wright brothers who made gliding flights and finally the first controlled and extended, manned powered flights. Spaceflight, particularly human spaceflight became

4640-409: The first passenger, Charles Furnas, one of their mechanics, on May 14, 1908. During the 1920s and 1930s great progress was made in the field of aviation, including the first transatlantic flight of Alcock and Brown in 1919, Charles Lindbergh 's solo transatlantic flight in 1927, and Charles Kingsford Smith 's transpacific flight the following year. One of the most successful designs of this period

4720-558: The first untethered human lighter-than-air flight on November 21, 1783, of a hot air balloon designed by the Montgolfier brothers . The usefulness of balloons was limited because they could only travel downwind. It was immediately recognized that a steerable, or dirigible , balloon was required. Jean-Pierre Blanchard flew the first human-powered dirigible in 1784 and crossed the English Channel in one in 1785. Rigid airships became

4800-430: The incoming voice transmission. Using ICAO radio protocol, they must verify with the transmitting operator that they are the intended message recipients. The crew then uses the received information. SELCAL details are defined in the latest version of ARINC Characteristic 714A. An individual aircraft is given a SELCAL code upon application to the SELCAL code registrar, Aviation Spectrum Resources, Inc. (ASRI). The code

4880-406: The introduction of composite materials to make small aircraft lighter and faster. Ultralight and homebuilt aircraft have also become increasingly popular for recreational use, since in most countries that allow private aviation, they are much less expensive and less heavily regulated than certified aircraft. Simple balloons were used as surveillance aircraft as early as the 18th century. Over

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4960-523: The introduction of the jet which permitted a major form of transport throughout the world. The word aviation was coined by the French writer and former naval officer Gabriel La Landelle in 1863. He originally derived the term from the verb avier (an unsuccessful neologism for "to fly"), itself derived from the Latin word avis ("bird") and the suffix -ation . There are early legends of human flight such as

5040-663: The motion of an aerodynamic object (wing) through the air, which due to its shape and angle deflects the air. For sustained straight and level flight, lift must be equal and opposite to weight. In general, long narrow wings are able deflect a large amount of air at a slow speed, whereas smaller wings need a higher forward speed to deflect an equivalent amount of air and thus generate an equivalent amount of lift. Large cargo aircraft tend to use longer wings with higher angles of attack, whereas supersonic aircraft tend to have short wings and rely heavily on high forward speed to generate lift. However, this lift (deflection) process inevitably causes

5120-493: 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 , because it was much more economical than other aircraft at that time. At the same time, turboprop propulsion started to appear for smaller commuter planes, making it possible to serve small-volume routes in a much wider range of weather conditions. Since

5200-399: The number of possible allowable codes to 10,920. Additionally, SELCAL codes assigned previously use a subset of only twelve letters/tones. Therefore, more than one aircraft may be designated by the same code. To avoid confusion from two or more aircraft using the same SELCAL code, ASRI tries to assign code duplicates to aircraft that do not usually operate in the same region of the world or on

5280-427: The only mammals capable of sustaining level flight (see bat flight ). However, there are several gliding mammals which are able to glide from tree to tree using fleshy membranes between their limbs; some can travel hundreds of meters in this way with very little loss in height. Flying frogs use greatly enlarged webbed feet for a similar purpose, and there are flying lizards which fold out their mobile ribs into

5360-412: The operation of aircraft, are reduced and controlled to an acceptable level. It encompasses the theory, practice, investigation, and categorization of flight failures, and the prevention of such failures through regulation, education, and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel. A maintenance, repair, and overhaul organization (MRO)

5440-410: The pitch of variable-pitch propeller blades, or using a thrust reverser on a jet engine. Rotary wing aircraft and thrust vectoring V/STOL aircraft use engine thrust to support the weight of the aircraft, and vector sum of this thrust fore and aft to control forward speed. In the context of an air flow relative to a flying body, the lift force is the component of the aerodynamic force that

5520-534: The possibility of flying machines becoming practical. Lilienthal's work led to him developing the concept of the modern wing. His flight attempts in Berlin in 1891 are seen as the beginning of human flight and the " Lilienthal Normalsegelapparat " is considered to be the first airplane in series production, making the Maschinenfabrik Otto Lilienthal in Berlin the first air plane production company in

5600-410: The purview of aerospace engineering which is subdivided into aeronautics , the study of vehicles that travel through the atmosphere, and astronautics , the study of vehicles that travel through space, and ballistics , the study of the flight of projectiles. Humans have managed to construct lighter-than-air vehicles that raise off the ground and fly, due to their buoyancy in the air. An aerostat

5680-444: The same HF radio frequencies. However, aircraft commonly move between different geographical regions and it is now routine for two aircraft with the same SELCAL code to be found flying in the same region. Therefore, air crew always verify both SELCAL and call sign (i.e., aircraft tail registration , or telephony designator and flight identification ) to be sure their aircraft is the intended recipient. A SELCAL 32 Expansion Project

5760-427: The same function without requiring that the aircraft move forward through the air). While common meanings of the word " lift " suggest that lift opposes gravity, aerodynamic lift can be in any direction. When an aircraft is cruising for example, lift does oppose gravity, but lift occurs at an angle when climbing, descending or banking. On high-speed cars, the lift force is directed downwards (called "down-force") to keep

5840-606: The stories of Icarus in Greek myth, Jamshid and Shah Kay Kāvus in Persian myth, and the flying automaton of Archytas of Tarentum (428–347 BC). Later, somewhat more credible claims of short-distance human flights appear, such as the winged flights of Abbas ibn Firnas (810–887, recorded in the 17th century), Eilmer of Malmesbury (11th century, recorded in the 12th century), and the hot-air Passarola of Bartholomeu Lourenço de Gusmão (1685–1724). The modern age of aviation began with

5920-603: The world support these manufacturers, who sometimes provide only the initial design and final assembly in their own plants. The Chinese ACAC consortium has also recently entered the civil transport market with its Comac ARJ21 regional jet. Until the 1970s, most major airlines were flag carriers , sponsored by their governments and heavily protected from competition. Since then, 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

6000-426: The world. Lilienthal is often referred to as either the "father of aviation" or "father of flight". Early dirigible developments included machine-powered propulsion ( Henri Giffard , 1852), rigid frames ( David Schwarz , 1896) and improved speed and maneuverability ( Alberto Santos-Dumont , 1901) There are many competing claims for the earliest powered, heavier-than-air flight. The first recorded powered flight

6080-442: 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. Aviation safety means the state of an aviation system or organization in which risks associated with aviation activities, related to, or in direct support of

6160-466: Was carried out by Clément Ader on October 9, 1890, in his bat-winged, fully self-propelled fixed-wing aircraft , the Ader Éole . It was reportedly the first manned, powered, heavier-than-air flight of a significant distance (50 m (160 ft)) but insignificant altitude from level ground. Seven years later, on October 14, 1897, Ader's Avion III was tested without success in front of two officials from

6240-415: Was highly flammable and allowed static electricity to build up in the airship. Changes to the coating formulation reduced the risk of further Hindenburg type accidents. Although there have been periodic initiatives to revive their use, airships have seen only niche application since that time. There had been previous airship accidents that were more fatal, for instance, a British R38 on 23 August 1921, but

6320-545: Was the Douglas DC-3 , which became the first airliner to be profitable carrying passengers exclusively, starting the modern era of passenger airline service. By the beginning of World War II, many towns and cities had built airports, and there were numerous qualified pilots available. During World War II one of the first jet engines was developed by Hans con Ohain, and accomplished the world's first jet-powered flight in 1939. The war brought many innovations to aviation, including

6400-810: Was the Tenerife airport disaster on March 27, 1977, when 583 people died when two Boeing 747 jumbo jets, operated by Pan Am and KLM collided on a runway in Los Rodeos airport, now known as Tenerife North. An aviation incident is defined as an occurrence, other than an accident, associated with the operation of an aircraft that affects or could affect the safety of operations. Air traffic control (ATC) involves communication with aircraft to help maintain separation – that is, they ensure that aircraft are sufficiently far enough apart horizontally or vertically for no risk of collision. Controllers may co-ordinate position reports provided by pilots, or in high traffic areas (such as

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