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An airliner is a type of aircraft for transporting
passenger A passenger (also abbreviated as pax) is a person who travels in a vehicle, but does not bear any responsibility for the tasks required for that vehicle to arrive at its destination or otherwise operate the vehicle, and is not a steward. The ...
s and
air cargo Air cargo is any property carried or to be carried in an aircraft. Air cargo comprises air freight, air express and airmail. Aircraft types Different cargo can be transported by passenger, cargo or combi aircraft: * Passenger aircraft use the ...
. Such aircraft are most often operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an airplane intended for carrying multiple passengers or cargo in commercial service. The largest of them are wide-body jets which are also called twin-aisle because they generally have two separate aisles running from the front to the back of the passenger cabin. These are usually used for long-haul flights between airline hubs and major cities. A smaller, more common class of airliners is the narrow-body or single-aisle. These are generally used for short to medium-distance flights with fewer passengers than their wide-body counterparts. Regional airliners typically seat fewer than 100 passengers and may be powered by turbofans or turboprops. These airliners are the non- mainline counterparts to the larger aircraft operated by the major carriers, legacy carriers, and flag carriers, and are used to feed traffic into the large airline hubs. These regional routes then form the spokes of a hub-and-spoke air transport model. The lightest ( light aircraft, list of light transport aircraft) of short-haul regional feeder airliner type aircraft that carry a small number of passengers are called commuter aircraft, commuterliners, feederliners, and air taxis, depending on their size, engines, how they are marketed, region of the world, and seating configurations. The
Beechcraft 1900 The Beechcraft 1900 is a 19-passenger, pressurized twin-engine turboprop regional airliner manufactured by Beechcraft. It is also used as a freight aircraft and corporate transport, and by several governmental and military organizations. With c ...
, for example, has only 19 seats.


History


Emergence

When the Wright brothers made the world's first sustained heavier-than-air flight, they laid the foundation for what would become a major transport industry. Their flight, performed in the Wright Flyer during 1903, was just 11 years before what is often defined as the world's first airliner.Tise, Larry E. Conquering the Sky. New York: Palgrave MacMillan, 2009. Print. By the 1960s, airliners had expanded capabilities, making a significant impact on global society, economics, and politics.Bernardo, James V. Aviation and Space: In the Modern World. New York: E.P. Dutton. 1968. During 1913, Igor Sikorsky developed the first large multi-engine airplane, the
Russky Vityaz The Sikorsky Russky Vityaz (russian: link=no, Русский витязь), or Russian Knight (S-21), previously known as the Bolshoi Baltisky (russian: link=no, Большой Балтийский) ''(The Great Baltic)'' in its first four-eng ...
. This aircraft was subsequently refined into the more practical Ilya Muromets, being furnished with dual controls for a pilot and copilot and a comfortable
cabin Cabin may refer to: Buildings * Beach cabin, a small wooden hut on a beach * Log cabin, a house built from logs * Cottage, a small house * Chalet, a wooden mountain house with a sloping roof * Cabin, small free-standing structures that serve as in ...
with a lavatory, cabin heating and lighting. This large four-engine biplane was further adapted into an early bomber aircraft, preceding subsequent transport and bomber aircraft. It first flew on 10 December 1913 and took off for its first demonstration flight with 16 passengers aboard on 25 February 1914. However, it was never used as a commercial airliner due to the onset of the First World War which led to military applications being prioritised.


Interwar period

In 1919, shortly after the end of the First World War, large numbers of ex-military aircraft flooded the market. One such aircraft was the French
Farman F.60 Goliath The Farman F.60 Goliath was a French airliner and bomber produced by the Farman Aviation Works from 1919. It was instrumental in the creation of early airlines and commercial routes in Europe after World War I. Design and development The ''G ...
, which had originally been designed as a long-range heavy bomber; a number were converted for commercial use into passenger airliners starting in 1919, being able to accommodate a maximum of 14 seated passengers. and around 60 were built. Initially, several publicity flights were made, including one on 8 February 1919, when the Goliath flew 12 passengers from Toussus-le-Noble to RAF Kenley, near Croydon, despite having no permission from the British authorities to land. Dozens of early airlines subsequently procured the type. One high-profile flight, made on 11 August 1919, involved an F.60 flying eight passengers and a ton of supplies from Paris via
Casablanca Casablanca, also known in Arabic as Dar al-Bayda ( ar, الدَّار الْبَيْضَاء, al-Dār al-Bayḍāʾ, ; ber, ⴹⴹⴰⵕⵍⴱⵉⴹⴰ, ḍḍaṛlbiḍa, : "White House") is the largest city in Morocco and the country's econom ...
and Mogador to Koufa, north of
Saint-Louis, Senegal Saint Louis or Saint-Louis ( wo, Ndar), is the capital of Senegal's Saint-Louis Region. Located in the northwest of Senegal, near the mouth of the Senegal River, and 320 km north of Senegal's capital city Dakar, it has a population officially ...
, flying more than . Another important airliner built in 1919 was the Airco DH.16; a redesigned Airco DH.9A with a wider fuselage to accommodate an enclosed cabin seating four passengers, plus pilot in an open cockpit. In March 1919, the prototype first flew at Hendon Aerodrome. Nine aircraft were built, all but one being delivered to the nascent airline,
Aircraft Transport and Travel Aircraft Transport and Travel Limited was a British airline formed during the First World War, a subsidiary of Airco. It was the first airline to operate a regular international flight (between London and Paris). History On 5 October 1916, Airc ...
, which used the first aircraft for pleasure flying, and on 25 August 1919, it inaugurated the first scheduled international airline service from London to Paris.Jackson 1973, p .62. One aircraft was sold to the River Plate Aviation Company in Argentina, to operate a cross-river service between Buenos Aires and
Montevideo Montevideo () is the Capital city, capital and List of cities in Uruguay, largest city of Uruguay. According to the 2011 census, the city proper has a population of 1,319,108 (about one-third of the country's total population) in an area of . M ...
. Meanwhile, the competing Vickers converted its successful First World War era bomber, the Vickers Vimy, into a civilian version, the Vimy Commercial. It was redesigned with a larger-diameter fuselage (largely of
spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...
plywood), and first flew from the Joyce Green airfield in Kent on 13 April 1919.Andrews and Morgan 1988, p. 95.Jackson 1988, p. 202. The world's first all-metal transport aircraft was the
Junkers F.13 The Junkers F 13 was the world's first all-metal transport aircraft, developed in Weimar Republic, Germany at the end of World War I. It was an advanced Cantilever#Aircraft, cantilever-wing monoplane, with enclosed accommodation for four passenge ...
, which also made its first flight in 1919. Junkers marketed the aircraft towards business travellers and commercial operators, and European entrepreneurs bought examples for their private use and business trips. Over 300 Junkers F 13s were built between 1919 and 1932. The Dutch
Fokker Fokker was a Dutch aircraft manufacturer named after its founder, Anthony Fokker. The company operated under several different names. It was founded in 1912 in Berlin, Germany, and became famous for its fighter aircraft in World War I. In 1919 ...
company produced the
Fokker F.II The Fokker F.II was the first of a long series of commercial aircraft from the Fokker Aircraft Company, flying in 1919. In a biplane age, it presented a distinct clean, high-wing monoplane style that sold successfully across Europe and North Amer ...
, then the enlarged F.III. These were used by the Dutch airline KLM, including on its Amsterdam-London service in 1921. A relatively reliable aircraft for the era, the Fokkers were flying to destinations across Europe, including Bremen, Brussels, Hamburg, and Paris. The
Handley Page Handley Page Limited was a British aerospace manufacturer. Founded by Frederick Handley Page (later Sir Frederick) in 1909, it was the United Kingdom's first publicly traded aircraft manufacturing company. It went into voluntary liquidation a ...
company in Britain produced the Handley Page Type W, its first civil transport aircraft. It housed two crew in an open
cockpit A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...
and 15 passengers in an enclosed cabin. Powered by two Napier Lion engines, the prototype first flew on 4 December 1919, shortly after it was displayed at the 1919 Paris Air Show at Le Bourget. It was ordered by the Belgian firm Sabena, a further ten Type Ws were produced under license in Belgium by
SABCA SABCA (Sociétés Anonyme Belge de Constructions Aéronautiques) is a Belgian aerospace company. Its main sectors of activity are civil aviation, space and defence. SABCA was established during 1920. Presently, it is owned by the French aircraf ...
. In 1921 the Air Ministry ordered three aircraft, built as the W.8b, for use by Handley Page Transport, and later by Imperial Airways, on services to Paris and Brussels. In France, the Bleriot-SPAD S.33 was introduced during the early 1920s. It was commercially successful, initially serving the Paris- London route, and later on continental routes. The enclosed cabin could carry four passengers with an extra seat in the cockpit. It was further developed into the
Blériot-SPAD S.46 The Blériot-SPAD S.46 was a small French airliner of the 1920s, developed from the Blériot-SPAD S.33. Like its predecessor, it was a conventional biplane that seated four passengers in an enclosed cabin while the pilot and occasionally a fif ...
. Throughout the 1920s, companies in Britain and France were at the forefront of the civil airliner industry. By 1921, the capacity of airliners needed to be increased to achieve more favourable economics. The English company
de Havilland The de Havilland Aircraft Company Limited () was a British aviation manufacturer established in late 1920 by Geoffrey de Havilland at Stag Lane Aerodrome Edgware on the outskirts of north London. Operations were later moved to Hatfield in H ...
, built the 10-passenger DH.29 monoplane,Jackson 1973, . while starting work on the design of the DH.32, an eight-seater
biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...
with a more economical but less powerful Rolls-Royce Eagle engine.Jackson 1987, pp. 508–525. For more capacity, DH.32 development was replaced by the DH.34 biplane, accommodating 10 passengers. A commercially successful aircraft, Daimler Airway ordered a batch of nine. The
Ford Trimotor The Ford Trimotor (also called the "Tri-Motor", and nicknamed the "Tin Goose") is an American three-engined transport aircraft. Production started in 1925 by the companies of Henry Ford and ended on June 7, 1933, after 199 had been made. It w ...
had two engines mounted on the wings and one in the nose, and a slabsided body, it carried eight passengers and was produced from 1925 to 1933. It was an important early airliner in America. It was used by the predecessor to
Trans World Airlines Trans World Airlines (TWA) was a major American airline which operated from 1930 until 2001. It was formed as Transcontinental & Western Air to operate a route from New York City to Los Angeles via St. Louis, Kansas City, and other stops, with F ...
, and by other airlines long after production ceased. The Trimotor helped to popularise numerous aspects of modern aviation infrastructure, including paved runways, passenger terminals, hangars, airmail, and radio navigation.Herrick, Greg A. ''fordtri-motor.com'', Yellowstone Aviation, Inc (Jackson, Wyoming), 2004. Retrieved: 4 April 2019. Pan Am opened up transoceanic service in the late 1920s and early 1930s, based on a series of large seaplanes – the Sikorsky S-38 through Sikorsky S-42.Daley, Robert, An American Saga, 1980, Random House, New York, , pp. 103-110. By the 1930s, the airliner industry had matured and large consolidated national airlines were established with regular international services that spanned the globe, including Imperial Airways in Britain,
Lufthansa Deutsche Lufthansa AG (), commonly shortened to Lufthansa, is the flag carrier of Germany. When combined with its subsidiaries, it is the second- largest airline in Europe in terms of passengers carried. Lufthansa is one of the five founding m ...
in Germany, KLM in the Netherlands, and United Airlines in America. Multi-engined aircraft were now capable of transporting dozens of passengers in comfort. During the 1930s, the British de Havilland Dragon emerged as a short-haul, low-capacity airliner. Its relatively simple design could carry six passengers, each with of luggage, on the London-Paris route on a fuel consumption of 13 gal (49 L) per hour. The DH.84 Dragon entered worldwide service. During early August 1934, one performed the first non-stop flight between the Canadian mainland and Britain in 30 hours 55 minutes, although the intended destination had originally been Baghdad in Iraq.Lewis 1971, p. 265. British production of the Dragon ended in favour of the de Havilland Dragon Rapide, a faster and more comfortable successor.Moss 1966, p. 3. By November 1934, series production of the Dragon Rapide had commenced.Moss 1966, p. 4. De Havilland invested into advanced features including elongated rear windows, cabin heating, thickened wing tips, and a strengthened airframe for a higher gross weight of .Moss 1966, p. 5. Later aircraft were amongst the first airliners to be fitted with flaps for improved landing performance, along with downwards-facing recognition light and metal propellers, which were often retrofitted to older aircraft.Moss 1966, p. 6. It was also used in military roles;Moss 1966, p. 4. civil Dragon Rapides were impressed into military service during the Second World War.Moss 1966, pp. 6-7. Metal airliners came into service in the 1930s. In the United States, the Boeing 247,"Model 247 Commercial Transport."
''boeing.com,'' 2009. Retrieved: 14 June 2010.
and the 14-passenger
Douglas DC-2 The Douglas DC-2 is a 14-passenger, twin-engined airliner that was produced by the American company Douglas Aircraft Company starting in 1934. It competed with the Boeing 247. In 1935, Douglas produced a larger version called the DC-3, which b ...
, flew during the first half of the decade, while the more powerful, faster, 21–32 passenger
Douglas DC-3 The Douglas DC-3 is a propeller-driven airliner manufactured by Douglas Aircraft Company, which had a lasting effect on the airline industry in the 1930s to 1940s and World War II. It was developed as a larger, improved 14-bed sleeper version ...
first appeared in 1935. DC-3s were produced in quantity for the Second World War and were sold as surplus afterward, becoming widespread within the commercial sector. It was one of first airliners to be profitable without the support of postal or government subsidies. Long-haul flights were expanded during the 1930s as Pan American Airways and Imperial Airways competed on transatlantic travel using fleets of
flying boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fusela ...
s, such as the British Short Empire and the American Boeing 314.Bogash, Robert A
"In Search of an Icon: The Hunt for a Boeing B-314 Flying Boat, Pan American NC18601 – the Honolulu Clipper"
''rbogash.com.'' Retrieved: 31 July 2011.
Imperial Airways' order for 28 Empire flying boats was viewed by some as a bold gamble. At the time, flying boats were the only practical means of building aircraft of such size and weight as land-based aircraft would have unfeasibly poor field performance.Norris 1966, p. 3. One Boeing 314, registration NC18602, became the first commercial plane to circumnavigate the globe during December 1941 and January 1942.


The postwar era


United Kingdom

In the United Kingdom, the
Brabazon Committee The Brabazon Committee was a committee set up by the British government in 1942 to investigate the future needs of the British Empire's civilian airliner market following World War II.Phipp, 2007, pp.15-16 The study was an attempt at defining, in ...
was formed in 1942 under John Moore-Brabazon, 1st Baron Brabazon of Tara to forecast advances in aviation technology and the air transport needs of the postwar British Empire (in South Asia, Africa, and the Near and Far East) and Commonwealth (
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, Canada, New Zealand).Masefield and Gunston, 2002, p. 82.Phipp 2007, p. 17. For British use, multi-engine aircraft types were allegedly split between the US for military transport aircraft and the UK for heavy bombers. That such a policy was suggested or implemented have been disputed, at least by Sir Peter Masefield.Masefield and Gunston, 2002, p. 97. British aircraft manufacturers were tied up to fulfill military requirements, and had no free capacity to address other matters though the war. The committee final report pushed four designs for the state-owned airlines British Overseas Airways Corporation (BOAC) and later British European Airways (BEA): three piston-powered aircraft of varying sizes, and a jet-powered 100-seat design at the request of Geoffrey de Havilland, involved in the first jet fighters development. After a brief contest, the Type I design was given to the
Bristol Aeroplane Company The Bristol Aeroplane Company, originally the British and Colonial Aeroplane Company, was both one of the first and one of the most important British aviation companies, designing and manufacturing both airframes and aircraft engines. Notable a ...
, building on a "100 ton bomber" submission.Barnes 1964, pp. 324-325. This evolved into the Bristol Brabazon but this project folded in 1951 as BOAC lost interest and the first aircraft needed a costly wing re-design to accommodate the
Bristol Proteus The Bristol Proteus was the Bristol Engine Company's first mass-produced gas turbine engine design, a turboprop that delivered just over 4,000 hp (3,000 kW). The Proteus was a reverse-flow gas turbine. Because the second turbine drov ...
engine.Phipp 2007, pp. 67-69. The Type II was split between the de Havilland Dove and Airspeed Ambassador conventional piston designs,Phipp 2007, pp. 75-77. and the Vickers model powered by newly developed turboprops: first flown in 1948, the VC.2 Viceroy was the first turboprop design to enter service;Phipp 2007, p. 81. a commercial success with 445 Viscounts built.Andrews and Morgan 1988, p. 537. The Type III requirement led to the conventional
Avro Tudor The Avro Type 688 Tudor was a British piston-engined airliner based on Avro's four-engine Lincoln bomber, itself a descendant of the famous Lancaster heavy bomber, and was Britain's first pressurised airliner. Customers saw the aircraft as ...
and the more ambitious
Bristol Britannia The Bristol Type 175 Britannia is a retired British medium-to-long-range airliner built by the Bristol Aeroplane Company in 1952 to fly across the Commonwealth. During development two prototypes were lost and the turboprop engines proved sus ...
, although both aircraft suffered protracted developments,Barnes 1964, pp. 347-348. with the latter entering service with BOAC in February 1957, over seven years following its order.Phipp 2007, pp. 105-109. The jet-powered Type IV became the de Havilland Comet in 1949. It featured an aerodynamically clean design with four
de Havilland Ghost The de Havilland Ghost (originally Halford H-2) was the de Havilland Engine Company's second design of a turbojet engine to enter production and the world's first gas turbine engine to enter airline service (with British Overseas Airways Corpo ...
turbojet engines buried in the wings, a pressurised fuselage, and large square windows. On 2 May 1952, the Comet took off on the world's first jetliner flight carrying fare-paying passengers and simultaneously inaugurated scheduled service between London and Johannesburg."On This Day: Comet inaugurates the jet age."
''BBC News,'' 2 May 1952. Retrieved 26 April 2012.
Cookman, Aubrey O. Jr
"I Rode The First Jet Airliner."
''Popular Mechanics'', July 1952, pp. 90–94. Retrieved 26 April 2012.
However, roughly one year after introduction, three Comets broke up mid-flight due to airframe metal fatigue, not well understood at the time. The Comet was grounded and tested to discover the cause, while rival manufacturers heeded the lessons learned while developing their own aircraft. The improved Comet 2 and the prototype Comet 3 culminated in the redesigned Comet 4 series which debuted in 1958 and had a productive career over 30 years, but sales never fully recovered.Phipp 2007, pp. 93-97.Jackson 1987, pp. 464-465. By the 1960s, the UK had lost the airliner market to the US due to the Comet disaster and a smaller domestic market, not regained by later designs like the BAC 1-11, Vickers VC10, and Hawker Siddeley Trident. The STAC committee was formed to consider
supersonic Supersonic speed is the speed of an object that exceeds the speed of sound ( Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times ...
designs and worked with Bristol to create the Bristol 223, a 100-passenger transatlantic airliner. The effort was later merged with similar efforts in France to create the Concorde supersonic airliner to share the cost.


United States

The first batch of the Douglas DC-4s went to the U.S. Army and Air Forces, and was named the C-54 Skymaster. Some ex-military DC-6s were later converted into airliners, with both passenger and cargo versions flooding the market shortly after the war's end. Douglas also developed a pressurized version of the DC-4, which it designated the Douglas DC-6. Rival company Lockheed produced the
Constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...
, a triple-tailed aircraft with a wider fuselage than the DC-4. The
Boeing 377 Stratocruiser The Boeing 377 Stratocruiser was a large long-range airliner developed from the C-97 Stratofreighter military transport, itself a derivative of the B-29 Superfortress. The Stratocruiser's first flight was on July 8, 1947. Its design was advanced ...
was based on the C-97 Stratofreighter military transport, it had a double deck and a pressurized fuselage. Convair produced the Convair 240, a 40-person pressurized airplane; 566 examples flew. Convair later developed the Convair 340, which was slightly larger and could accommodate between 44 and 52 passengers, of which 311 were produced. The firm also commenced work on the Convair 37, a relatively large double-deck airliner that would have served trans continental routes; however, the project was abandoned due to a lack of customer demand and its high development costs. Rival planes include the Martin 2-0-2 and Martin 4-0-4, but the 2-0-2 had safety concerns and was unpressurized, while the 4-0-4 only sold around 100 units.Jarrett, Phillip. eds. Modern Air Transport: Worldwide Air Transport from 1945 to the Present. London: Putnam, 2000. During the postwar years, engines became much larger and more powerful, and safety features such as deicing, navigation, and weather information were added to the planes. American planes were allegedly more comfortable and had superior flight decks than those produced in Europe.


France

In 1936, the French Air Ministry requested transatlantic flying boats that could hold at least 40 passengers, leading to three
Latécoère 631 The Latécoère 631 was a civil transatlantic flying boat built by Latécoère, the largest ever built up to its time. The type was not a success, being unreliable and uneconomic to operate. Five of the eleven aircraft built were written off in ...
s introduced by Air France in July 1947. However, two crashed and the third was removed from service over safety concerns. The SNCASE Languedoc was the first French post-war airliner. Accommodating up to 44 seats, 40 aircraft were completed for Air France between October 1945 and April 1948. Air France withdrew the last Languedoc from its domestic routes in 1954, being replaced by later designs. First flying in February 1949, the four-engined Breguet Deux-Ponts was a double-decker transport for passengers and cargo. Air France used it on its busiest routes, including from Paris to the Mediterranean area and to London. The Sud-Aviation Caravelle was developed during the late 1950s as the first short range jet airliner. The nose and cockpit layout were licensed from the de Havilland Comet, along with some fuselage elements. Entering service in mid 1959, 172 Caravelles had been sold within four years and six versions were in production by 1963. Sud Aviation then focused its design team on a Caravelle successor. The Super-Caravelle was a supersonic transport project of similar size and range to the Caravelle. It was merged with the similar
Bristol Aeroplane Company The Bristol Aeroplane Company, originally the British and Colonial Aeroplane Company, was both one of the first and one of the most important British aviation companies, designing and manufacturing both airframes and aircraft engines. Notable a ...
project into the Anglo-French Concorde. The Concorde entered service in January 1967 as the second and last commercial supersonic transport,Gordon and Rigmant 2005, after large overruns and delays, costing £1.3 billion. All subsequent French airliner efforts were part of the Airbus pan-European initiative.


USSR

Soon after the war, most of the Soviet fleet of airliners consisted of DC-3s or Lisunov Li-2s. These planes were in desperate need of replacement, and in 1946, the Ilyushin Il-12 made its first flight. The Il-12 was very similar in design to American Convair 240, except was unpressurized. In 1953, the
Ilyushin Il-14 The Ilyushin Il-14 (NATO reporting name: Crate) was a Soviet twin-engine commercial and military personnel and cargo transport aircraft that first flew in 1950, and entered service in 1954. The Il-14 was also manufactured in East Germany by VEB ...
made its first flight, and this version was equipped with much more powerful engines. The main contribution that the Soviets made in regards to airliners was the
Antonov An-2 The Antonov An-2 ("kukuruznik"—corn crop duster; USAF/DoD reporting name Type 22, NATO reporting name Colt) is a Soviet mass-produced single-engine biplane utility/agricultural aircraft designed and manufactured by the Antonov Design Bure ...
. This plane is a biplane, unlike most of the other airliners, and sold more units than any other transport plane.


Types


Narrow-body airliners

The most common airliners are the narrow-body aircraft, or single-aisles. The earliest jet airliner were narrowbodies: the initial de Havilland Comet, the
Boeing 707 The Boeing 707 is an American, long-range, narrow-body airliner, the first jetliner developed and produced by Boeing Commercial Airplanes. Developed from the Boeing 367-80 prototype first flown in 1954, the initial first flew on December 20, ...
and its competitor the Douglas DC-8. They were followed by smaller models : the Douglas DC-9 and its
MD-80 The McDonnell Douglas MD-80 is a series of five-abreast single-aisle airliners developed by McDonnell Douglas. It was produced by the developer company until August 1997 and then by Boeing Commercial Airplanes. The MD-80 was the second gener ...
/ MD-90/ Boeing 717 derivatives; the Boeing 727,
737 737 most commonly refers to: * Boeing 737, an American narrow-body passenger airplane ** Boeing 737 Classic ** Boeing 737 MAX ** Boeing 737 Next Generation * AD 737, a year in the common era * 737 BC, a year * 737 (number), a number 737 may als ...
and 757 using the 707 cabin cross-section; or the Tupolev Tu-154,
Ilyushin IL-18 The Ilyushin Il-18 (russian: Илью́шин Ил-18; NATO reporting name: Coot) is a large turboprop airliner that first flew in 1957 and became one of the best known and most durable Soviet aircraft of its era. The Il-18 was one of the world ...
, and the
Ilyushin IL-62 The Ilyushin Il-62 (russian: Илью́шин Ил-62; NATO reporting name: Classic) is a Soviet long-range narrow-body jetliner conceived in 1960 by Ilyushin. As successor to the popular turboprop Il-18 and with capacity for almost 200 pa ...
. Currently produced narrow-body airliners include the Airbus A220 and A320 family, Boeing 737 and
Embraer E-Jet family The Embraer E-Jet family is a series of four-abreast narrow-body short- to medium-range twin-engine jet airliners designed and produced by the Brazilian aerospace manufacturer Embraer. The E-Jet was designed as a complement to the preceding E ...
, generally used for medium-haul flights with 100 to 240 passengers. They could be joined by the in-development
Comac C919 The Comac C919 is a narrow-body airliner developed by Chinese aircraft manufacturer Comac. The development program was launched in 2008. Production of the prototype began in December 2011, with the first prototype being ready on 2 November 201 ...
and Irkut MC-21.


Wide-body airliners

The larger wide-body aircraft, or twin-aisle as they have two separate aisles in the cabin, are used for long-haul flights. The first was the
Boeing 747 The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022. After introducing the 707 in October 1958, Pan Am wanted a jet times its size, t ...
quadjet, followed by the trijets: the Lockheed L-1011 and the Douglas DC-10, then its MD-11 stretch. Then other quadjets were introduced: the Ilyushin Il-86 and Il-96, the Airbus A340 and the double-deck
A380 The Airbus A380 is a large wide-body airliner that was developed and produced by Airbus. It is the world's largest passenger airliner and only full-length double-deck jet airliner. Airbus studies started in 1988, and the project was annou ...
. Twinjets were also put into service: the Airbus A300/ A310, A330 and
A350 The Airbus A350 is a long-range, wide-body twin-engine jet airliner developed and produced by Airbus. The first A350 design proposed by Airbus in 2004, in response to the Boeing 787 Dreamliner, would have been a development of the A330 w ...
; the
767 767 may refer to: * Boeing 767, a jet airliner * 767 (number) * AD 767, a year in the 8th century. * 767 BC, a year in the 8th century BC * Area code 767 Area code 767 is the local telephone area code of the Commonwealth of Dominica, within the ...
,
777 777 may refer to: * 777 (number), a number * AD 777, a year of the Julian calendar * 777 BC, a year in the 8th century BC * Boeing 777, a commercial jet airliner :* Boeing 777X, the newer generation of the Boeing 777. Art and entertainment Alb ...
and 787.


Regional aircraft

Regional airliners seat fewer than 100 passengers. These smaller aircraft are often used to feed traffic at large airline hubs to larger aircraft operated by the major mainline carriers, legacy carriers, or flag carriers; often sharing the same livery. Regional jets include the Bombardier CRJ100/200 and Bombardier CRJ700 series, or the Embraer ERJ family. Currently produced turboprop regional airliners include the
Dash-8 The De Havilland Canada DHC-8, commonly known as the Dash 8, is a series of turboprop-powered regional airliners, introduced by de Havilland Canada (DHC) in 1984. DHC was later bought by Boeing in 1988, then by Bombardier in 1992; then by ...
series, and the
ATR 42 The ATR 42 is a regional airliner produced by Franco-Italian manufacturer ATR, with final assembly in Toulouse, France. On 4 November 1981, the aircraft was launched with ATR, as a joint venture between French Aérospatiale (now Airbus) and ...
/ 72.


Commuter aircraft

Light aircraft can be used as small commuter airliners, or as air taxis. Twin turboprops carrying up to 19 passengers include the
Beechcraft 1900 The Beechcraft 1900 is a 19-passenger, pressurized twin-engine turboprop regional airliner manufactured by Beechcraft. It is also used as a freight aircraft and corporate transport, and by several governmental and military organizations. With c ...
, Fairchild Metro, Jetstream 31, DHC-6 Twin Otter and Embraer EMB 110 Bandeirante. Smaller airliners include the single-engined turboprops like the Cessna Caravan and
Pilatus PC-12 The Pilatus PC-12 is a pressurized, single-engined, turboprop aircraft, manufactured by Pilatus Aircraft of Stans, Switzerland, since 1991. It was designed as a high-performance utility aircraft that incorporates a large aft cargo door in ad ...
; or twin piston-powered aircraft made by
Cessna Cessna () is an American brand of general aviation aircraft owned by Textron Aviation since 2014, headquartered in Wichita, Kansas. Originally, it was a brand of the Cessna Aircraft Company, an American general aviation aircraft manufacturing c ...
, Piper,
Britten-Norman Britten-Norman (BN) is a privately owned British aircraft manufacturer and aviation services provider. The company is the sole independent commercial aircraft producer in the United Kingdom. Britten-Norman has so far manufactured and sold almost ...
, and Beechcraft. They often lack lavatories, stand-up cabins, pressurization, galleys, overhead storage bins, reclining seats, or a
flight attendant A flight attendant, also known as steward/stewardess or air host/air hostess, is a member of the aircrew aboard commercial flights, many business jets and some government aircraft. Collectively called cabin crew, flight attendants are prima ...
.


Engines

Until the beginning of the Jet Age,
piston engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...
s were common on propliners such as the Douglas DC-3. Nearly all modern airliners are now powered by turbine engines, either turbofans or turboprops. Gas turbine engines operate efficiently at much higher altitudes, are more reliable than piston engines, and produce less vibration and noise. The use of a common fuel type – kerosene-based jet fuel – is another advantage.


Airliner variants

Some variants of airliners have been developed for carrying freight or for luxury corporate use. Many airliners have also been modified for government use as VIP transports and for military functions such as airborne tankers (for example, the Vickers VC10, Lockheed L-1011,
Boeing 707 The Boeing 707 is an American, long-range, narrow-body airliner, the first jetliner developed and produced by Boeing Commercial Airplanes. Developed from the Boeing 367-80 prototype first flown in 1954, the initial first flew on December 20, ...
), air ambulance ( USAF/ USN McDonnell Douglas DC-9), reconnaissance ( Embraer ERJ 145, Saab 340, and Boeing 737), as well as for troop-carrying roles.


Configuration

Modern jetliners are usually low-wing designs with two engines mounted underneath the
swept wing A swept wing is a wing that angles either backward or occasionally forward from its root rather than in a straight sideways direction. Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds was first investigate ...
s, while ( turboprop aircraft are slow enough to use straight wings. Smaller airliners sometimes have their engines mounted on either side of the rear fuselage. Numerous advantages and disadvantages exist due to this arrangement. Perhaps the most important advantage to mounting the engines under the wings is that the total aircraft weight is more evenly distributed across the wingspan, which imposes less bending moment on the wings and allows for a lighter wing structure. This factor becomes more important as aircraft weight increases, and no in-production airliners have both a maximum takeoff weight more than 50 tons and engines mounted on the fuselage. The
Antonov An-148 The Antonov An-148 ( ua, Антонов Ан-148) is a regional jet designed and built by Antonov of Ukraine. Development of the aircraft was started in the 1990s, and its maiden flight took place on 17 December 2004. The aircraft completed its ...
is the only in-production jetliner with high-mounted wings (usually seen in military transport aircraft), which reduces the risk of damage from unpaved runways. Except for a few experimental or military designs, all aircraft built to date have had all of their weight lifted off the ground by airflow across the wings. In terms of aerodynamics, the fuselage has been a mere burden. NASA and Boeing are currently developing a blended wing body design in which the entire airframe, from wingtip to wingtip, contributes lift. This promises a significant gain in
fuel efficiency Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
.


Current manufacturers

The major manufacturers with large aircraft airliners currently in production include: * Airbus (France/Germany/Spain/United Kingdom) * Antonov (Ukraine) * ATR Aircraft (France/Italy) * Boeing (United States) * Comac (China) *
Embraer Embraer S.A. () is a Brazilian multinational aerospace manufacturer that produces commercial, military, executive and agricultural aircraft, and provides aeronautical services. It was founded in 1969 in São José dos Campos, São Paulo, where i ...
(Brazil) * Irkut Corporation (
UAC UAC may refer to: Computing * User Account Control, a security feature in Microsoft Windows * Session Initiation Protocol#User agent client Organizations * Ulster Army Council, 1973 Northern Ireland loyalist paramilitary group * Undeb Amaet ...
, Russia, includes Sukhoi) * Xi'an Aircraft Industrial Corporation (China) The narrow-body and wide-body airliner market is dominated by Airbus and Boeing, and the regional airliner market is shared between ATR Aircraft and
Embraer Embraer S.A. () is a Brazilian multinational aerospace manufacturer that produces commercial, military, executive and agricultural aircraft, and provides aeronautical services. It was founded in 1969 in São José dos Campos, São Paulo, where i ...
. Setting up a reliable customer support network, ensuring uptime, availability and support 24/7 and anywhere, is critical for the success of airliner manufacturers. Boeing and Airbus are ranked 1 and 2 in customer satisfaction for aftermarket support by a survey by Inside MRO and Air Transport World, and this is a reason why Mitsubishi Aircraft Corporation purchased the Bombardier CRJ program. It is an entry barrier for new entrants like the Xian MA700 and
Comac C919 The Comac C919 is a narrow-body airliner developed by Chinese aircraft manufacturer Comac. The development program was launched in 2008. Production of the prototype began in December 2011, with the first prototype being ready on 2 November 201 ...
, with no credible previous experience with the MA60, or the Irkut MC-21 after the Sukhoi Superjet 100.


Notable airliners

* Boeing 247 – the first modern airliner, with all-metal construction and retractable landing gear *
Douglas DC-3 The Douglas DC-3 is a propeller-driven airliner manufactured by Douglas Aircraft Company, which had a lasting effect on the airline industry in the 1930s to 1940s and World War II. It was developed as a larger, improved 14-bed sleeper version ...
– very widespread, still serving * Boeing 307 Stratoliner – the first with a pressurized cabin * Douglas DC-6 – derived from the Douglas DC-4 * Boeing 377- developed from the C-97 Stratofreighter * Vickers Viscount – the first turboprop airliner * Lockheed Constellation – one of the largest propeller-driven airliners *
Antonov An-2 The Antonov An-2 ("kukuruznik"—corn crop duster; USAF/DoD reporting name Type 22, NATO reporting name Colt) is a Soviet mass-produced single-engine biplane utility/agricultural aircraft designed and manufactured by the Antonov Design Bure ...
– a single engine biplane, a widespread large utility aircraft


Notable jetliners

* De Havilland Comet – the first operational jetliner, grounded by early crashes *
Tupolev Tu-104 The Tupolev Tu-104 (NATO reporting name: Camel) is a retired twinjet, medium-range, narrow-body turbojet-powered Soviet airliner. It was the second to enter regular service, behind the British de Havilland Comet, and was the only jetliner operat ...
– the first twinjet, developed into the first turbofan-powered airliner, the Tupolev Tu-124 *
Boeing 707 The Boeing 707 is an American, long-range, narrow-body airliner, the first jetliner developed and produced by Boeing Commercial Airplanes. Developed from the Boeing 367-80 prototype first flown in 1954, the initial first flew on December 20, ...
– the most successful early jetliner, along the less widespread Douglas DC-8 *
Sud Aviation Caravelle The Sud Aviation SE 210 Caravelle is a French jet airliner produced by Sud Aviation. It was developed by SNCASE in the early 1950s and made its maiden flight on 27 May 1955. It included some de Havilland designs and components developed for t ...
– the first jetliner with rear podded engines, the configuration of the more widespread Douglas DC-9 * Boeing 737 – the most successful jet airliner by deliveries * Tupolev Tu-144 – the first operational supersonic transport * Concorde – the most successful supersonic airliner, operating until 2003 *
Boeing 747 The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022. After introducing the 707 in October 1958, Pan Am wanted a jet times its size, t ...
– the first wide-body aircraft and first high-bypass turbofan-powered airliner, the largest passenger airliner until the A380 * McDonnell Douglas DC-10 – the first trijet wide-body, along the later
Lockheed L-1011 TriStar The Lockheed L-1011 TriStar, also known as the L-1011 (pronounced "El-ten-eleven") and TriStar, is an American medium-to-long-range, wide-body trijet airliner built by the Lockheed Corporation. It was the third wide-body airliner to enter comme ...
* Airbus A300 – the first twinjet wide-body, followed by the
Boeing 767 The Boeing 767 is an American wide-body aircraft developed and manufactured by Boeing Commercial Airplanes. The aircraft was launched as the 7X7 program on July 14, 1978, the prototype first flew on September 26, 1981, and it was certified on ...
* Airbus A320 – the first airliner with fly-by-wire flight controls, the most ordered jet airliner * Boeing 777 – the largest twinjet * Airbus A380 – full double-deck aircraft, the largest passenger airliner * Boeing 787 – the first airliner mostly constructed with composite materials


In production aircraft


Fleet

The airliner fleet went from 13,500 in 2000 to 25,700 in 2017: 16% to 30.7% in Asia/Pacific (2,158 to 7,915), 34.7% to 23.6% in USA (4,686 to 6,069) and 24% to 20.5% in Europe (3,234 to 5,272). In 2018, there were 29,398 airliners in service: 26,935 passenger transports and 2,463 freighters, while 2,754 others were stored. The largest fleet was in Asia-Pacific with 8,808 (5% stored), followed by 8,572 in North America (10% stored), 7,254 in Europe (9% stored), 2,027 in Latin America, 1,510 in Middle East and 1,347 in Africa. Narrowbody are dominant with 16,235, followed by 5,581 Widebodies, 3,743 Turboprops, 3,565 Regional jets and 399 Others. By the end of 2018, there were 1,826 parked or in storage jetliners out of 29,824 in service (6.1%): 1,434 narrowbodies and 392 widebodies, down from 9.8% of the fleet at the end of 2012 and 11.3% at the end of 2001.


Market

Since it began, the jet airliner market had a recurring pattern of seven years of growth followed by three years of deliveries falling 30–40%, except a steady growth from 2004 due to the economic rise of China going from 3% of world market in 2001 to 22% in 2015, expensive
jet fuel Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial a ...
till 2014 stimulating old jets replacement allowed by low interest rates since 2008, and strong airline passenger demand since. In 2004, 718 Airbus and Boeings were delivered, worth $39.3 billion; 1,466 are expected in 2017, worth $104.4 billion: a growth by 3.5 from 2004 to 2020 is unprecedented and highly unusual for any mature market. In 2016, the deliveries went for 38% in Asia-Pacific, 25% in Europe, 22% in North America, 7% in Middle East, 6% in South America and 2% in Africa. 1,020 narrowbodies were delivered and their backlog reach : 4,991 A320neo, A320ceo; 3,593 737 Max, 835 737NG, 348 CSeries, 305 C919 and 175 MC-21; while 398 widebodies were delivered : 137 Dreamliners and 99 B777 for Boeing (65%) against 63 A330 and 49 A350 for Airbus, more than 2,400 widebodies were in backlog, led by the A350 with 753 (31%) then the Boeing 787 with 694 (28%). The most important driver of orders is airline profitability, itself driven mainly by world GDP growth but also
supply and demand In microeconomics, supply and demand is an economic model of price determination in a Market (economics), market. It postulates that, Ceteris paribus, holding all else equal, in a perfect competition, competitive market, the unit price for a ...
balance and oil prices, while new programmes by Airbus and Boeing help to stimulate aircraft demand. In 2016, 38% of the 25 years old airliners had been retired, 50% of the 28 years old : there will be 523 aircraft reaching 25 years old in 2017, 1,127 in 2026 and 1,628 in 2041. Deliveries rose by 80% from 2004 to 2016, they represented 4.9% of the fleet in 2004 and 5.9% in 2016, down from 8% previously. Oil prices and airshow orders are trending together. In 2020, deliveries were down by more than 50% compared to 2019 due to the impact of the COVID-19 pandemic on aviation, after 10 years of growth.


Storage, scrapping and recycling

Storage can be an adjustment variable for the airliner fleet: as Jan–Apr 2018 RPKs are up by 7% over a year and
FTK FTK may refer to: * Forensic Toolkit, digital forensics software * For the Kids (disambiguation) * " Fuck the Kells", a song by American punk rock band Tijuana Sweetheart * First Turn Kill (Trading Card Game) * Godman Army Airfield Godman Army A ...
s up by 5.1%, the
IATA The International Air Transport Association (IATA ) is a trade association of the world's airlines founded in 1945. IATA has been described as a cartel since, in addition to setting technical standards for airlines, IATA also organized tariff ...
reports 81 net aircraft went back from storage (132 recalled and 51 stored) in April. It is the second month of storage contraction after eight of expansion and the largest in four years, while new aircraft deliveries fell slightly to 448 from 454 due to supply-chain issues and in-service issues grounding others. Retirements were down by 8% and utilization up by 2%, according to
Canaccord Genuity Canaccord Genuity Group Inc. is a global, full-service investment banking and financial services company that specializes in wealth management and brokerage firm, brokerage in capital markets. It is the largest independent investment dealer in C ...
, driving used aircraft and engines values up while MRO shops have unexpected demand for legacy products like the PW4000 and GE CF6.


Cabin configurations and features

An airliner will usually have several classes of seating: first class, business class, and/or economy class (which may be referred to as coach class or tourist class, and sometimes has a separate "premium" economy section with more legroom and amenities). The seats in more expensive classes are wider, more comfortable, and have more amenities such as "lie flat" seats for more comfortable sleeping on long flights. Generally, the more expensive the class, the better the beverage and meal service. Domestic flights generally have a two-class configuration, usually first or business class and coach class, although many airlines instead offer all-economy seating. International flights generally have either a two-class configuration or a three-class configuration, depending on the airline, route and aircraft type. Many airliners offer movies or audio/video on demand (this is standard in first and business class on many international flights and may be available on economy). Cabins of any class are provided with lavatory facilities, reading lights and gaspers. Larger airliners may have a segregated rest compartment reserved for crew use during breaks.


Seats

The types of seats that are provided and how much legroom is given to each passenger are decisions made by the individual airlines, not the aircraft manufacturers. Seats are mounted in "tracks" on the floor of the cabin and can be moved back and forth by the maintenance staff or removed altogether. Naturally the airline tries to maximize the number of seats available in every aircraft to carry the largest possible (and therefore most profitable) number of passengers. Passengers seated in an exit row (the row of seats adjacent to an
emergency exit An emergency exit in a structure is a special exit for emergencies such as a fire: the combined use of regular and special exits allows for faster evacuation, while it also provides an alternative if the route to the regular exit is blocked. ...
) usually have substantially more legroom than those seated in the remainder of the cabin, while the seats directly in front of the exit row may have less legroom and may not even recline (for evacuation safety reasons). However, passengers seated in an exit row may be required to assist cabin crew during an
emergency evacuation Emergency evacuation is the urgent immediate egress or escape of people away from an area that contains an imminent threat, an ongoing threat or a hazard to lives or property. Examples range from the small-scale evacuation of a building due t ...
of the aircraft opening the emergency exit and assisting fellow passengers to the exit. As a precaution, many airlines prohibit young people under the age of 15 from being seated in the exit row. The seats are designed to withstand strong forces so as not to break or come loose from their floor tracks during turbulence or accidents. The backs of seats are often equipped with a fold-down tray for eating, writing, or as a place to set up a portable computer, or a music or video player. Seats without another row of seats in front of them have a tray that is either folded into the armrest or that clips into brackets on the underside of the armrests. However, seats in premium cabins generally have trays in the armrests or clip-on trays, regardless of whether there is another row of seats in front of them. Seatbacks now often feature small colour
LCD A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directly but in ...
screens for videos, television and video games. Controls for this display as well as an outlet to plug in audio headsets are normally found in the armrest of each seat.


Overhead bins

The overhead bins, also known as overhead lockers or pivot bins, are used for stowing carry-on baggage and other items. While the airliner manufacturer will normally specify a standard version of the product to supply, airlines can choose to have bins of differing size, shape, or color installed. Over time, overhead bins evolved out of what were originally overhead shelves that were used for little more than coat and briefcase storage. As concerns about falling debris during turbulence or in accidents increased, enclosed bins became the norm. Bins have increased in size to accommodate the larger carry-on baggage passengers can bring onto the aircraft. Newer bin designs have included a handrail, useful when moving through the cabin.


Passenger service units

Above the passenger seats are Passenger Service Units (PSU). These typically contain reading lights, air vents, and a flight attendant call light. On most narrowbody aircraft (and some Airbus A300s and A310s), the flight attendant call button and the buttons to control the reading lights are located directly on the PSU, while on most widebody aircraft, the flight attendant call button and the reading light control buttons are usually part of the
in-flight entertainment In-flight entertainment (IFE) refers to the entertainment available to aircraft passengers during a flight. In 1936, the airship ''LZ 129 Hindenburg, Hindenburg'' offered passengers a piano, lounge, dining room, smoking room, and bar during the ...
system. The units frequently have small "Fasten Seat Belt" and "No Smoking" illuminated signage and may also contain a speaker for the cabin public address system. On some newer aircraft, a "Turn off electronic devices" sign is used instead of the "No Smoking" sign, as smoking isn't permitted on board the aircraft anyway. The PSU will also normally contain the drop-down
oxygen mask An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover only the nose and mouth (oral nasal mask) or the entire face (full-face mask). They may be made of plastic, silicone, or r ...
s which are activated if there is a sudden drop in cabin pressure. These are supplied with oxygen by means of a chemical oxygen generator. By using a chemical reaction rather than a connection to an oxygen tank, these devices supply breathing oxygen for long enough for the airliner to descend to thicker, more breathable air. Oxygen generators do generate considerable heat in the process. Because of this, the oxygen generators are thermally shielded and are only allowed in commercial airliners when properly installed – they are not permitted to be loaded as freight on passenger-carrying flights. ValuJet Flight 592 crashed on May 11, 1996, as a result of improperly loaded chemical oxygen generators.


Cabin pressurization

Airliners developed since the 1940s have had pressurized cabins (or, more accurately, pressurized hulls including baggage holds) to enable them to carry passengers safely at high altitudes where low oxygen levels and air pressure would otherwise cause sickness or death. High altitude flight enabled airliners to fly above most weather systems that cause turbulent or dangerous flying conditions, and also to fly faster and further as there is less drag due to the lower air density. Pressurization is applied using compressed air, in most cases bled from the engines, and is managed by an environmental control system which draws in clean air, and vents stale air out through a valve. Pressurization presents design and construction challenges to maintain the structural integrity and sealing of the cabin and hull and to prevent rapid decompression. Some of the consequences include small round windows, doors that open inwards and are larger than the door hole, and an emergency oxygen system. To maintain a pressure in the cabin equivalent to an altitude close to sea level would, at a cruising altitude around , create a pressure difference between inside the aircraft and outside the aircraft that would require greater hull strength and weight. Most people do not suffer ill effects up to an altitude of , and maintaining cabin pressure at this equivalent altitude significantly reduces the pressure difference and therefore the required hull strength and weight. A side effect is that passengers experience some discomfort as the cabin pressure changes during ascent and descent to the majority of airports, which are at low altitudes.


Cabin climate control

The air bled from the engines is hot and requires cooling by air conditioning units. It is also extremely dry at cruising altitude, and this causes sore eyes, dry skin and
mucosa A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
on long flights. Although
humidification A humidifier is a device, primarily an electrical appliance, that increases humidity (moisture) in a single room or an entire building. In the home, point-of-use humidifiers are commonly used to humidify a single room, while whole-house or furnac ...
technology could raise its relative humidity to comfortable middle levels, this is not done since humidity promotes corrosion to the inside of the hull and risks
condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
which could
short Short may refer to: Places * Short (crater), a lunar impact crater on the near side of the Moon * Short, Mississippi, an unincorporated community * Short, Oklahoma, a census-designated place People * Short (surname) * List of people known as ...
electrical systems, so for safety reasons it is deliberately kept to a low value, around 10%. Another problem of the air coming from the ventilation (unto which the oil lubrication system of the engines is hooked up) is that fumes from components in the synthetic oils can sometimes travel along, causing passengers, pilots and crew to be intoxicated. The illness it causes is called aerotoxic syndrome.


Baggage holds

Airliners must have space on board to store "checked" baggage – that which will not safely fit in the passenger cabin. Designed to hold baggage as well as freight, these compartments are called "cargo bins", "holds", or occasionally "pits". Occasionally baggage holds may be referred to as cargo decks on the largest of aircraft. These compartments can be accessed through doors on the outside of the aircraft. Depending on the aircraft, baggage holds are normally inside the hull and are therefore pressurized just like the passenger cabin although they may not be heated. While lighting is normally installed for use by the loading crew, typically the compartment is unlit when the door is closed. Baggage holds on modern airliners are equipped with fire detection equipment and larger aircraft have automated or remotely activated fire-fighting devices installed.


Narrow-body airliners

Most " narrow-body" airliners with more than 100 seats have space below the cabin floor, while smaller aircraft often have a special compartment separate from the passenger area but on the same level. Baggage is normally stacked within the bin by hand, sorted by destination category. Netting that fits across the width of the bin is secured to limit movement of the bags. Airliners often carry items of freight and mail. These may be loaded separately from the baggage or mixed in if they are bound for the same destination. For securing bulky items "hold down" rings are provided to tie items into place.


Wide-body airliners

" Wide-body" airliners frequently have a compartment like the ones described above, typically called a "bulk bin". It is normally used for late arriving luggage or bags which may have been checked at the gate. However, most baggage and loose freight items are loaded into containers called Unit Load Devices (ULDs), often referred to as "cans". ULDs come in a variety of sizes and shapes, but the most common model is the LD3. This particular container has approximately the same height as the cargo compartment and fits across half of its width. ULDs are loaded with baggage and are transported to the aircraft on dolly carts and loaded into the baggage hold by a loader designed for the task. By means of belts and rollers an operator can maneuver the ULD from the dolly cart, up to the aircraft baggage hold door, and into the aircraft. Inside the hold, the floor is also equipped with drive wheels and rollers that an operator inside can use to move the ULD properly into place. Locks in the floor are used to hold the ULD in place during flight. For consolidated freight loads, like a pallet of boxes or an item too oddly shaped to fit into a container, flat metal pallets that resemble large baking sheets that are compatible with the loading equipment are used.


See also


Lists

* Regional jets *
List of civil aircraft List of civil aircraft is a list of articles on civilian aircraft with descriptions, which excludes aircraft operated by military organizations in civil markings, warbirds, warbirds used for racing, replica warbirds and research aircraft. A ABC ...
* List of regional airliners * List of airliners by maximum takeoff weight


Topics

* Aircraft design process * Aircraft spotting * Aviation and the environment * Aviation safety * Flight length * Flight planning


References


Bibliography

* Andrews, C.F. and Eric B. Morgan. ''Vickers Aircraft since 1908, Second edition''. London: Putnam, 1988. . * Barnes, C.H. ''Bristol Aircraft since 1910''. London: Putnam, First Edition, 1964 (1987 reprint). . * Chillon J., J-P Dubois and J.Wegg. ''French Postwar Transport Aircraft.'' Tonbridge, Kent, UK: Air-Britain (Historians) Limited. 1980. . * Faith, Nicholas. ''Black Box: Why Air Safety is no Accident, The Book Every Air Traveller Should Read''. London: Boxtree, 1996. . * * . * Jackson, A.J. ''British Civil Aircraft since 1919: Volume II''. London:Putnam, Second edition 1973. . * Jackson, A.J. ''British Civil Aircraft 1919–1972: Volume III''. London: Putnam, revised second edition, 1988. . * * * * Norris, Geoffrey. ''The Short Empire Boats'' (Aircraft in Profile Number 84). Leatherhead, Surrey, UK: Profile Publications Ltd., 1966. * *


Further reading

* * * * {{Authority control Russian inventions