An airliner is a large fixed-wing aircraft A fixed-wing aircraft, typically called an airplane, aeroplane or plane, is an aircraft capable of flight using forward motion that generates lift as the wing moves through the air. Planes include jet engine and propeller driven vehicles propelled forward by thrust, as well as unpowered aircraft . Fixed-wing aircraft are distinct from ornithopters for transporting passengers and cargo. Such planes are owned by airlines An airline provides air transport services for passengers or freight, generally with a recognized operating certificate or license. Airlines lease or own their aircraft with which to supply these services and may form partnerships or alliances with other airlines for mutual benefit.

The definition of an airliner can vary from country to country.

History

If an airliner is defined as a plane intended for carrying multiple passengers in commercial service, the Russian Sikorsky Ilya Muromets The Il'ya Muromets was a four-engine bomber developed in 1913. It was based on the Russky Vityaz, the first 4-engined aircraft designed by Igor Sikorsky. The Il'ya Muromets aircraft was the world's first four-engine bomber, and became the basis for Russia's first, dedicated strategic bombing unit. The aircraft was named after Ilya Muromets, a hero was the first official passenger aircraft. The Ilya Muromets was a luxurious aircraft with an isolated passenger saloon An aircraft cabin is the section of an aircraft in which passengers travel, often just called the cabin. At cruising altitudes, the surrounding atmosphere is too thin to breath without an oxygen mask, so cabin pressurization adapts the cabin to atmospheric pressures, wicker chairs, bedroom, lounge and a bathroom. The aircraft also had heating A heater is any object that emits heat or causes another body to achieve a higher temperature. In a household or domestic setting, heaters are usually appliances whose purpose is to generate heating . Heaters exists for all states of matter, including solids, liquids and gases and electrical lighting Lighting or illumination is the deliberate application of light to achieve some aesthetic or practical effect. Lighting includes use of both artificial light sources such as lamps and natural illumination of interiors from daylight. Daylighting is often used as the main source of light during daytime in buildings given its low cost. Artificial. The Ilya Muromets first flew on December 10, 1913. On February 25, 1914, it took off for its first demonstration flight with 16 passengers aboard. From June 21 – June 23, it made a round-trip from Saint Petersburg Saint Petersburg (Russian: Санкт-Петербург , tr. Sankt-Peterburg, pronounced [sankt pʲɪtʲɪrˈburk]) is a city and a federal subject (a federal city) of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea. The city's other names were Petrograd (Russian: Петроград, IPA [pʲɪtrɐˈgrat], 19 to Kiev Kiev or Kyiv (Ukrainian: Київ [ˈkɪjiw]; Russian: Киев); see also Cities' alternative names), is the capital and the largest city of Ukraine, located in the north central part of the country on the Dnieper River. The population as of the 2001 census was 2,611,300. However, higher numbers have been cited in the press in 14 hours and 38 minutes with one intermediate landing. If it had not been for World War I World War I was a military conflict that lasted from 1914 to 1918 and involved most of the world's great powers, assembled in two opposing alliances: the Allies and the Central Powers. More than 70 million military personnel, including 60 million Europeans, were mobilized in one of the largest wars in history. More than 15 million people were, the Ilya Muromets would have probably started passenger flights that same year.

The second airliner was the Farman F.60 Goliath The Farman F.60 Goliath was an airliner 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 from 1919, which could seat up to 14 passengers, approximately 60 were built.

The Ford Trimotor The Ford Trimotor was an American three engine civil transport aircraft first produced in 1925 by Henry Ford and continued in production until June 7, 1933. Throughout its lifespan a total of 199 aircraft were produced. Although designed for the civil market, the aircraft was also used by the military and was sold all over the world. Unlike his was an important early airliner. With 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 used by the predecessor to TWA Trans World Airlines renamed TWA Airlines LLC in 2001 was a major United States-based airline with hubs in St. Louis, New York (JFK),with focus cities in Kansas City, Missouri; San Juan, Puerto Rico; and Los Angeles, California. The airline operated from 1930 until it was acquired by American Airlines in 2001. Prior to the buyout, TWA was one of as well as other airlines long after production ceased. In 1932 the 14-passenger Douglas DC-2 The Douglas DC-2 was a 14-seat, twin-propeller airliner produced by the Douglas Aircraft Corporation starting in 1934. It competed with the Boeing 247. In 1935 Douglas produced a larger version called the DC-3, which became one of the most successful airplanes in history flew and in 1935 the more powerful, faster, 21–32 passenger Douglas DC-3 The Douglas DC-3 is an American fixed-wing, propeller-driven aircraft whose speed and range revolutionized air transport in the 1930s and 1940s. Because of its lasting impact on the airline industry and World War II it is generally regarded as one of the most significant transport aircraft ever made. Many DC-3s are still used to this day in all. DC-3s were produced in quantity for WWII and sold as surplus afterward.

The first jet airliners In contrast to today's relatively fuel-efficient, turbofan-powered air travel, first generation jet airliner travel was noisy and fuel inefficient. These inefficiencies were addressed by the invention of turboprop and turbofan engines came in the immediate post war era. Turbojet Turbojets are the oldest kind of general-purpose jet engines. Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany, developed the concept independently into practical engines during the late 1930s, although credit for the first turbojet is given to Whittle who was first to conceive, first to formally describe, first to engines were trialled on piston engine A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used extensively in motor vehicles; the steam engine, the mainstay of the airframes such as the Avro Lancastrian The Avro 691 Lancastrian was a British passenger and mail transport aircraft of the 1940s and 1950s developed from the Avro Lancaster heavy bomber. The Lancaster was named after Lancaster, Lancashire; a Lancastrian is an inhabitant of Lancaster and the Vickers VC.1 Viking The Vickers VC.1 Viking was a British twin-engine short-range airliner derived from the Vickers Wellington bomber and built by Vickers Armstrongs Limited at Brooklands near Weybridge in Surrey. In the aftermath of the war, the Viking was an important airliner with British airlines pending the development of turboprop aircraft like the Viscount. An the latter becoming the first jet engined passenger aircraft in April 1948. The first purpose built jet airliners were the de Havilland Comet The de Havilland Comet was the world's first commercial jet airliner to reach production. Developed and manufactured by de Havilland, it first flew in 1949 and was considered a landmark in British aeronautical design. After introduction into commercial service, the initial Comet versions suffered from catastrophic metal fatigue, causing two well- (UK) and the Avro Jetliner The Avro C102 Jetliner was a Canadian prototype medium-range jet airliner built by Avro Canada in 1949. It was beaten into the air by only 13 days by the de Havilland Comet, thereby becoming the second jet airliner in the world, yet the name "Jetliner" was more catchy and for many years all such aircraft were colloquially given that name (Canada). The former entered production and service while the latter did not. The Comet was unfortunate in that metal fatigue caused crashes.

Jets did not immediately replace piston engines and many designs used the turboprop Turboprop engines are a type of aircraft powerplant that use a gas turbine to drive a propeller. The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller. The engine's exhaust gases contain little energy compared to a jet engine and play a minor role in the propulsion of the rather than the turbojet or the later turbofan engines.

Types

Wide-body airliners

The largest airliners are wide-body A wide-body aircraft is a large airliner with two passenger aisles, also known as a twin-aisle aircraft. The typical fuselage diameter is 5 to 6 m . In the typical widebody economy cabin, passengers are seated seven to ten abreast, allowing a total capacity of 200 to 600 passengers. The largest widebody aircraft are over 6 m (20 ft) wide, and can jets. These aircraft are frequently called twin-aisle aircraft because they generally have two separate aisles running from the front to the back of the passenger cabin. Aircraft in this category are the Boeing 747 The Boeing 747 is a widebody commercial airliner and cargo transport, often referred to by the nickname Jumbo Jet or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first widebody ever produced. Manufactured by Boeing's Commercial Airplane unit in the United States, the original version of the 747 was two and a, Boeing 767 The Boeing 767 is a mid-size, wide-body twinjet airliner produced by Boeing Commercial Airplanes. Passenger versions of the 767 can carry between 181 and 375 passengers, and have a range of 5,200 to 6,590 nautical miles depending on variant and seating configuration. The Boeing 767 has been produced in three fuselage lengths. The original 767-200, Boeing 777 The Boeing 777 is a long-range, wide-body twin-engine jet airliner manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and is commonly referred to as the "Triple Seven". The aircraft has seating for over 300 passengers and has a range from 5,235 to 9,380 nautical miles depending on model. Its distinguishing, Airbus A300 The Airbus A300 is a short- to medium-range widebody aircraft. Launched in 1972 as the world's first twin-engined widebody, it was the first product of the Airbus consortium of European aerospace companies, wholly owned today by EADS. The A300 ceased production in July 2007, along with the smaller A310. Freighter sales for which the A300 competed/A310 The Airbus A310 is a medium- to long-range widebody airliner. Launched in 1978, it was the second aircraft created by the Airbus consortium of European aerospace companies, which is now fully owned by EADS. The A310 is a shortened derivative of the A300, the first twin-engined widebody airliner. The A310 officially ceased production in July 2007, Airbus A330 The Airbus A330 is a large-capacity, wide-body, twin-engine, medium-to-long-range commercial passenger airliner. Built at Toulouse in France by Airbus, over 600 units have been delivered, Airbus A340 The Airbus A340 is a long-range four-engined wide-body commercial passenger airliner manufactured by Airbus, a subsidiary of EADS. It seats between 261 and 380 passengers, and has a range between 6,700 and 9,000 NM . It is similar in design to the twin-engined A330. Initial A340 versions share the fuselage and wing of the A330 while later models, Airbus A380 The Airbus A380 is a double-deck, wide-body, four-engine airliner manufactured by the European corporation Airbus, a subsidiary of EADS. The largest passenger airliner in the world, the A380 made its maiden flight on 27 April 2005 from Toulouse, France, and made its first commercial flight on 25 October 2007 from Singapore to Sydney with Singapore, Lockheed L-1011 TriStar The Lockheed L-1011 TriStar, commonly referred to as just L-1011 or TriStar, is a medium-to-long range, three-engine, widebody passenger jet airliner. It was the third widebody airliner to enter commercial operations, following the Boeing 747 and the McDonnell Douglas DC-10. Between 1968 and 1984, Lockheed manufactured a total of 250 TriStars, McDonnell Douglas DC-10, McDonnell Douglas MD-11 The McDonnell Douglas MD-11 is an American three-engine medium to long-range widebody airliner, with two engines mounted on underwing pylons and a third engine at the base of the vertical stabilizer. It is based on the DC-10, but featuring a stretched fuselage, increased wingspan with winglets, refined airfoils on the wing and tailplane, new, Ilyushin Il-86 The Ilyushin Il-86 is a medium-range wide-body jet airliner. Designed and tested by the Ilyushin design bureau in the 1970s, it was certificated by the Soviet aircraft industry during the 1970s and 1980s, manufactured jointly in the USSR and Poland, and marketed by the USSR. It was the first Soviet wide-body airliner and the world's second four- and Ilyushin Il-96 The Ilyushin Il-96 is a four-engined long-haul widebody airliner designed by Ilyushin in the Russian Federation and manufactured by the Voronezh Aircraft Production Association in Voronezh. It is powered by four Aviadvigatel PS-90 two-shaft turbofan engines. These aircraft are usually used for long-haul flights between airline hubs and major cities with many passengers. Future wide-body models include the Boeing 787 The Boeing 787 Dreamliner is a long range, mid-sized, wide-body, twin-engine jet airliner developed by Boeing Commercial Airplanes. It seats 210 to 330 passengers, depending on variant. Boeing states that it is the company's most fuel-efficient airliner and the world's first major airliner to use composite materials for most of its construction and Airbus A350 The Airbus A350 is a long-range, mid-size, wide-body family of airliners currently under development by European manufacturer Airbus. The A350 will be the first Airbus with both fuselage and wing structures made primarily of carbon fiber-reinforced plastic. The A350 is designed to compete with the Boeing 777 and the Boeing 787. Airbus claims that.

Narrow-body airliners

A smaller, more common class of airliners is the narrow-body A narrow-body aircraft is an airliner with a fuselage aircraft cabin diameter typically of 3 to 4 metres , and airline seat arranged 2 to 6 abreast along a single aisle. Often called single aisle aircraft. Narrow-body aircraft with a range not allowing transatlantic or transcontinental flights are commonly known as regional airliners or single aisle aircraft. These smaller airliners are generally used for medium-distance flights with fewer passengers than their wide-body counterparts.

Examples include the Boeing 717 The Boeing 717 is a twin-engine, single-aisle jet airliner, developed for the 100-seat market. The airliner was designed and marketed by McDonnell Douglas as the MD-95, a third-generation derivative of the DC-9, 737 The Boeing 737 is a short to medium range, single aisle, narrow body jet airliner. Originally developed as a shorter, lower-cost twin-engine airliner derived from Boeing's 707 and 727, the 737 has nine variants with the -600, -700, -800 and -900 currently in production, 757 The Boeing 757 is a mid-size, narrow-body twinjet airliner manufactured by Boeing Commercial Airplanes. Passenger versions of the 757 can carry between 186 and 279 passengers, and have a maximum range of 3,100 to 3,900 nautical miles depending on variant and seating configuration. The Boeing 757 has been produced in two fuselage lengths: the, McDonnell Douglas DC-9 The McDonnell Douglas DC-9 is a twin-engine, single-aisle jet airliner. It was first manufactured in 1965 with its maiden flight later that year. The DC-9 was designed for frequent, short flights. The final DC-9 was delivered in October 1982 and MD-80/MD-90 The McDonnell Douglas MD-80 series are twin-engine, medium-range, single-aisle commercial jet airliners. The MD-80 aircraft were lengthened and updated from the DC-9. The MD-80 series can seat from 130 up to 172 passengers depending on variant and seating arrangement series, Airbus A320 family The Airbus A320 family of short- to medium-range commercial passenger airliners are manufactured by Airbus and are the only narrowbody in their product line. Family members include the A318, A319, A320, and A321, as well as the ACJ business jet, Tupolev Tu-204 The Tupolev Tu-204 is a twin-engined medium range Russian airliner capable of carrying 212 passengers. First introduced in 1989, it is considered to be broadly equivalent to the Boeing 757. It was developed for Aeroflot as a replacement for the medium range Tupolev Tu-154 trijet, Tu-214, Embraer E-Jets 190&195 The Embraer E-Jets are a series of narrow body, twin-engined, medium range, jet airliners produced in Brazil. Announced at the Paris Air Show in 1999, and entering production in 2002, the aircraft have been a success – as of December 31, 2008, there are 876 firm orders for E-Jets and 810 options. The manufacturer reported that 600 units had been and Tu-334. Older airliners like the Boeing 707, 727, McDonnell Douglas DC-8, Fokker F70/F100, VC10, Tupolev, and Yakovlev jets also fit into this category.

Small Airliners

Short haul airliners used by airlines and regional airlines

Regional airliners - Small (Regional) short haul airliners typically seat fewer than 100 passengers and may be powered by turbofans or turboprops.

These airliners, though smaller than aircraft operated by most major carriers, legacy carriers, flag carriers, frequently serve customers who expect service, similar to that offered by the far larger airlines with their longer ranged larger jetliners. Therefore, these short haul airliners are usually equipped with lavatories, stand up cabins, pressurization, overhead storage bins, reclining seats, and have a flight attendant to look after the in-flight needs of the passengers upon point-to-point routes. Among some of earliest regional short haul airliners were the pre-airline deregulation Jetstream 31 aircraft.

Feederliner Aircraft used by regional airlines

Regional airliners - (Regional) Feederliners 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 or focus cities. These particular routes may need the size of a smaller aircraft to meet the frequency needs and service levels, customers expect in the marketed product that is offered by larger airlines and their modern narrow and widebody aircraft. Therefore, most regional airliners are equipped with lavatories and have a flight attendant to look after the in-flight needs of the passengers, along with the features of a short haul regional airliner.

Typical aircraft in this category include the Bombardier CRJ and Embraer ERJ regional jets along with the "Q" (DASH-8) series, ATR 42/72 and Saab 340/2000 turboprop airliners. Airlines and their partners sometimes use these for flights between small hubs, or for bringing passengers to hub cities where they may board larger aircraft. Typically, these regional feederliners, are painted in the aircraft liveries and color schemes of the much larger airline partners so the regional airlines may offer and market a seamless transition between the larger airline to smaller airline.

Commuterliner aircraft used by regional airlines and air taxi charter operators

The lightest (light aircraft, list of light transport aircraft) of short haul regional feeder airliner type aircraft that carry 19 or fewer passenger seats 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, for example, has only 19 seats. Depending on local and national regulations, a commuter aircraft may not qualify as an airliner and may not be subject to the regulations applied to larger aircraft. Members of this class of aircraft normally lack such amenities as lavatories and galleys and typically do not carry a flight attendant as an aircrew member.

Other aircraft that may fall into this category are the Fairchild Metro, Jetstream 31, and Embraer EMB 110 Bandeirante. The Cessna Caravan and Pilatus PC-12, are single-engine turboprops, sometimes used as a small airliner, although many countries stipulate a minimum requirement of two engines for aircraft to be used as airliners.

Twin piston-engined aircraft made by Cessna, Piper, Britten-Norman, and Beechcraft are also in use as short haul, short range commuter type aircraft.

Engines

Until the beginning of the jet age, piston engines were common on propliners like 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. Prior to the jet age it was common for the same or very similar engines to be used in civilian airliners as in military aircraft. In recent years, divergence has occurred so that it is now unusual for the same engine to be used on a military type as a civilian type. Usually military aircraft which share engine technology with airliners are transports or tanker types.

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 VC-10, Lockheed L1011, Boeing 707), air ambulance (USAF/USN McDonnell-Douglas DC-9), reconnaissance (Embraer ERJ 145, Saab 340, Boeing 737), as well as for troop-carrying roles.

Layout

Modern airliners are usually low-wing designs with engines mounted in underwing pods (usually two of them). For airliners, multi-engine design is mandated by some national regulations so that aircraft can continue to climb even in the worst case of power loss in one engine right after take-off. Another regulatory demand is that aircraft are able to fly a minimum specified amount of time after one engine fails in flight (see ETOPS).

Mounting the engines underneath and to the fore of the wing moves weight from the fuselage to the wings, imposing less bending moment on them and allowing for a lighter wing structure. After this feature proved successful in military jets, Boeing introduced it to its 707 airliner design and it has been increasingly adopted since.^[1]

Mounting the engines in underwing pods also makes physical access for maintenance quicker and easier compared to tail-mounted engines.

Additionally, low wing design helps keep the engine nacelles and refueling valves closer to the ground to simplify access and the wing's surface acts as a barrier to prevent the engines' noise from reaching the fuselage in-flight.

Both Airbus and Boeing use this common layout for all of their current passenger aircraft and emerging manufacturers (e.g. Embraer and Sukhoi Superjet) follow the same scheme.

In a few special cases, where engine proximity to ground is detrimental (e.g. rural airfields with risk of foreign object damage or dirt), airliners will feature tail-mounted engines (e.g. MD-80 or Tu-334) or high-wing designs with underhung nacelles (e.g. BAE-146). These planes become rarer as almost all newly built airliners have underwing nacelles. Tail-engined designs are mostly used by business jet manufacturers.

Future airliners may feature innovative delta wing or lifting body outlines.

Manufacturers

These include:

• Asia
  • China
    • Commercial Aircraft Corporation of China (includes Shanghai Aircraft Manufacturing Factory)
    • Shenyang Aircraft Corporation
    • Xi'an Aircraft Industrial Corporation

• Europe
  • • Airbus S.A.S. (formerly a multinational conglomeration of the largest European aerospace companies of France, Germany, Spain and the UK)
  • Czech Republic
    • Let Kunovice
  • France/Italy
    • ATR
  • Netherlands
    • Fokker (now defunct)
  • Russian companies (formerly Soviet-controlled)
    • Ilyushin
    • Sukhoi
    • Tupolev
    • Yakovlev
  • Sweden
    • Saab (no longer manufactures civilian aircraft)
  • Ukraine (formerly Soviet-controlled)
    • Antonov
  • United Kingdom
    • BAE Systems (formerly British Aerospace, no longer manufactures civilian aircraft)
    • Britten-Norman

• North America
  • Canada
    • Bombardier (includes the former De Havilland Canada and Canadair)
  • United States
    • Boeing (includes the former McDonnell Douglas company which itself included the Douglas Aircraft Company)
    • Lockheed Corporation (now part of Lockheed-Martin, and no longer involved in civil aviation)

• South America
  • Brazil
    • Embraer

The international market for middle-sized and large-sized airliners is now divided between Airbus and Boeing, though Russian/former Soviet manufacturers still sell significant numbers of airliners to their traditional markets. Smaller-sized aircraft manufacturers include, in addition to these two, ATR, Embraer and Bombardier.

Notable airliners

• Boeing 247 – the first design to incorporate modern features such as all-metal construction and retractable landing gear
• Douglas DC-3 – still in service more than 70 years after its debut, it is generally regarded as one of the most significant transport aircraft ever made
• Douglas DC-6 – originally developed as a military transport, it was reworked for passenger service after World War II, a role it continues to perform today
• Vickers Viscount – the first turboprop airliner to enter service
• Lockheed Constellation – a distinctive triple-tailed piston-engined airliner of the 1950s, it was one of the last large propeller-driven airliners
• De Havilland Comet – the world's first jetliner to reach mass production, its reputation was marred by a series of crashes due to structural failure
• Sud Aviation Caravelle – one of the more successful European first-generation turbojet airliners
• Tupolev Tu-104 – the first turbojet airliner to provide sustained service, and the sole jetliner operating in the world between 1956 and 1958
• Boeing 707 – the first United States-built jetliner to enter production
• Douglas DC-8 – launched after the Boeing 707, it nevertheless established Douglas in the airliner market, and continues to serve as a cargo aircraft to this day
• Boeing 727 – was the most produced commercial jet airliner in the world for over a decade, with 1,831 aircraft produced
• Douglas DC-9 – production of it and successive variants nearly reached 2,500
• Boeing 737 – currently the best selling civilian jet airliner
• Tupolev Tu-144 – the first supersonic transport aircraft constructed in Soviet Union
• Concorde – an Anglo-French supersonic transport, it remains the only supersonic aircraft to sustain a regular passenger service
• Boeing 747 "jumbo jet" – an iconic aircraft, it was the world's largest airliner between 1968 and 2005
• Douglas DC-10 – a trijet competitor to the widebody 747
• Lockheed L-1011 TriStar – shared a similar configuration to the DC-10, but not its success, with only 250 produced
• Airbus A300 – the world's first twinjet widebody
• Airbus A320 – pioneered the use of fly-by-wire technology
• Airbus A340-600 - longest commercial airplane
• Boeing 777 – the first airliner designed entirely by computer, without physical mockups
• Airbus A380 "superjumbo" – the world's largest airliner from 2005 onwards
• Boeing 787 - the world's first jet airliner to make use of composite materials for most of its construction

Airliner recycling

As airliners are very expensive, most are leased out for times typically from 20 to 40 years. Very few go back into service after a long lease is up because evolving aerospace technology leaves older airliners unable to compete against newer machines that can be operated at a lower cost. Many end-of-service airliners end up in the Mojave Desert, at the Mojave Spaceport (also known as "The Boneyard"). From this, the term "Mojave" has come to refer to the temporary storage of aircraft, e.g. during decreased demand for air travel and between short-term leases. Another airliner retirement location is Marana, Arizona.

While almost every airliner will be reduced to scrap (the exceptions end up as museum pieces or flown by collector groups) they may pass through many owners before they are retired. A well-maintained airliner can operate safely for decades, depending on how often it is flown, its operating environment, and whether damage and wear and tear is properly repaired.

What may end an airliner's working life is a lack of spare parts, as the original manufacturer and third manufacturers may no longer provide or support them. Corrosion and metal fatigue are other issues that become more expensive to deal with as time goes on. Eventually, these factors and advances in aircraft technology lead to older airliners becoming too expensive or inefficient to operate.

To protect the environment, the Airbus company has set up a centre in France to decommission and recycle older aircraft. More than 200 airliners will finish active life each year, and will be dismantled and recycled under the newly established PAMELA Project.

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 (see board toilets).

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) 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 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 [1].

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 color LCD 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 are used for stowing carry-on baggage and other items. While the airliner manufacturer will normally supply a standard product, airlines may choose to have bins of differing size, shape, or color installed. Over time, these bins evolved out of what were originally overhead shelves 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 in order to accommodate the larger carry-on baggage passengers may bring onto the aircraft. New bin designs may include a handrail, useful when moving through the cabin.

Passenger service units

Above the passenger seats are Passenger Service Units (PSU). These typically contain a reading light, air vent, and a flight attendant call button. 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.

The PSU will also normally contain the drop-down oxygen masks 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. Pressurisation is applied using compressed air, in most cases bled from the engines, and is managed by a 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 10,000 m (33,000 feet), 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 1800–2500 m (6000–8000 feet), 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 and dry skin and mucosa on long flights. Although humidification 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 which could short electrical systems, so for safety reasons it is deliberately kept to a low value, around 10%.

Baggage holds

Airliners must have space on board to store baggage that 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. Despite what is seen in many movies, access doors between passenger cabins and baggage holds are rare in modern airliners.

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 regional airliners
• List of airliners by Maximum Takeoff Weight

Topics

• Airport
• Air travel
• Air safety
• Flight planning
• Aircraft spotting
• Aviation and the environment

Notes

1. ^ Cacutt, Len (ed.) (1986). The World's Greatest Aircraft. Aerospace Publishing.

External links and references

• Boeing
• Airbus (EADS)
• Embraer
• Bombardier
• ATR
• Canadian Air Transport Security Authority (CATSA) website
• Airliners.net
• Airplanes.se

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