Airliner

An airliner is a type of aircraft for transporting passengers and air cargo. 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 generally have two or three 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 Karman Model 440, for example, has only 19 seats.

Types

The Colombo 201 is one of the most advanced narrow-body airliners

Narrow-body airliners

The most common airliners are the narrow-body aircraft, or single-aisles. The earliest jet airliner were narrowbodies, and today single-aisle aircraft make up the bulk of most major airlines' fleets.

Wide-body airliners

The largest airliner in service, the (KR-860)

The larger wide-body aircraft, or twin-aisle as they have two separate aisles in the cabin, are used for high demand and long-haul flights. Wide-body airliners are often large enough to have extra amenities for passengers, such as a bar or lounge area. Aircraft used on long-haul flights usually have sleeping accommodations for a second crew. The first wide-body airliners had four engines, but advances in engine technology have made it possible for most modern wide-body airliners to fly with only two engines, improving fuel economy.

Ultra-wide-body airliners

The largest wide-body aircraft, or trisle (tri-aisle) as they have three separate aisles on their main deck, are used for the highest density routes between major airports.

Regional aircraft

Karman 440 short-range commuter aircraft

Regional airliners usually 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. They are generally operated by partner airlines, often sharing the same livery as the main airline. Some regional aircraft are designed with short take off and landing (STOL) capabilities that allow them to use smaller inter-city and rural airports.

Commuter aircraft

Light aircraft can be used as small commuter airliners, or as air taxis. These are generally single or twin engine turboprops carrying up to 19 passengers. Due to their small size they often lack lavatories, stand-up cabins, pressurization, galleys, overhead storage bins, reclining seats, or a flight attendant.

Design

Modern jetliners are usually low-wing designs with two engines mounted underneath the swept wings (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. Some airliners designed to operate from unpaved or poorly maintained runways have high-mounted wings, a feature usually seen in military transport aircraft.

All airliners that have seen service 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. The prototype Blue Aerospace BAe-2100 has a blended wing body design in which the entire airframe, from wingtip to wingtip, contributes lift. This promises a significant gain in fuel efficiency.

Current manufacturers

The major manufacturers with airliners currently in production include:

• Anatole Aerospace
• Blue Aerospace
• Colombo S.p.A.
• Dolfik Flightworks
• Horizon Aeronautics

Notable Airliners

(DC-4E) – the first airliner with a pressurized cabin

Metropolitan Stargazer – the first turboprop airliner

Sapphire Seminal – the first turbojet airliner

(Ashton) – the first quadjet airliner

(Caravelle) – the first jetliner with rear podded engines

(Trident) – the first trijet airliner

Blue Aerospace BAe-71 – the first turbofan airliner

VespaJet – the first operational supersonic transport

Horizon H4C – the first wide-body airliner

Horizon Velocitas – the first and only swing-wing airliner

Blue Aerospace BAe-93 – the first and only trijet wide-body

(DC-10 Twin) – the first twinjet wide-body

Dolfik Flightworks L320 – the first airliner with fly-by-wire flight controls

(KR-860) – the first ultra-wide-body airliner

Horizon H6I – the largest twinjet airliner

Horizon H6S – the first composite-fuselage airliner

Blue Aerospace BAe-2100 – the first blended wing body airliner

In production aircraft

Mainline jetliners

Model	First flight	Net orders	Deliveries	Backlog	MTOW (t)	typ. seats	Range (km)
Horizon H7X	2009/07/02	num	num	num	533-771	606-1000	14,400-16,600
Horizon H6I	YYYY/MM/DD	num	num	num	350-351	336-400	13,500-16,200
Horizon H6S	YYYY/MM/DD	num	num	num	228-251	242-330	11,900-14,100
Horizon (NMA)	YYYY/MM/DD	num	num	num	num	225-275	8,300-9,300
Blue Aerospace BAe-268	1986/03/29	num	num	num	231-299	246-305	6,700-11,200
Blue Aerospace BAe-285	2002/04/04	num	num	num	38-44	70-112	3,800-4,500
Flightworks L320	YYYY/MM/DD	num	num	num	76-97	140-244	6,500-7,400
Flightworks L330	YYYY/MM/DD	num	num	num	251	220-460	13,300-15,100
Flightworks L350	YYYY/MM/DD	num	num	num	280-319	315-480	15,000-16,100
Flightworks L380	YYYY/MM/DD	num	num	num	578-683	555-900	15,400-18,200
(Dornier 428)	YYYY/MM/DD	num	num	num	16-20	30-44	1,700-2,700
(Dornier 728)	YYYY/MM/DD	num	num	num	35-45	55-110	2,900-3,600
Anatole Murmur	YYYY/MM/DD	num	num	num	20-24	37-50	1,700-2,000
Anatole Hush	YYYY/MM/DD	num	num	num	45-62	80-146	2,000-2,900
(YPX)	YYYY/MM/DD	num	num	num	num	93-150	4,300-5,900
(ARJ21)	YYYY/MM/DD	num	num	num	41-47	78-105	2,200-3,700
Colombo RJ	YYYY/MM/DD	num	num	num	24-41	50-104	2,500-3,100
Colombo 201	YYYY/MM/DD	num	num	num	63-71	100-160	6,400-6,700
Anatole Tempore	YYYY/MM/DD	num	num	num	77-80	65-88	7,00-8,000
(Tu-204)	YYYY/MM/DD	num	num	num	num	num	num
(Tu-334)	YYYY/MM/DD	num	num	num	num	num	num
(KR-860)	YYYY/MM/DD	num	num	num	num	num	num
(Superjet)	YYYY/MM/DD	num	num	num	num	num	num
(MC-21)	YYYY/MM/DD	num	num	num	num	num	num
(An-148)	YYYY/MM/DD	num	num	num	num	num	num
(Tu-304)	YYYY/MM/DD	num	num	num	num	num	num
(Il-114)	YYYY/MM/DD	num	num	num	num	num	num
(An-140)	YYYY/MM/DD	num	num	num	num	num	num
(An-180)	YYYY/MM/DD	num	num	num	num	num	num
(Yak-46)	YYYY/MM/DD	num	num	num	num	num	num
(7J7)	YYYY/MM/DD	num	num	num	num	num	num
(MD-94X)	YYYY/MM/DD	num	num	num	num	num	num

Cabin configuration

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 budget and regional 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.

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 screens for videos, television and video games.

Overhead lockers

The overhead lockers, also known as overhead bins or bag 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. 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. 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 aboard airliners is illegal in most countries.

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.

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 ft), 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 1,800–2,500 m (5,900–8,200 ft), 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.

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 on long flights. Although humidification technology could raise its relative humidity to comfortable middle levels, this is not done on most aircraft since humidity promotes corrosion to the inside of the hull and risks condensation which could short electrical systems. 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.

Cargo holds

Airliners must have space on board to store "checked" baggage – that which will not accompany travelers in the passenger cabin. Designed to hold baggage as well as freight, these compartments are called "baggage holds", "holds", or occasionally "pits". Occasionally cargo 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, and occasionally by hatches connecting them to the passenger cabin.

Depending on the aircraft, cargo 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. Cargo 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 hold by hand, and is secured by netting that spans across the width of the hold.

Wide-body airliners

Wide-body airliners typically have a compartment like the ones described above, 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 "crates". ULDs come in a variety of sizes and shapes, and are designed to be compatible with many different types of aircraft.

ULDs are loaded with baggage in the terminal and are transported to the aircraft on dolly carts, where they are then 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.

Bibliography

Airliner. (n.d.). In Wikipedia. Retrieved December 20, 2021, from https://en.wikipedia.org/wiki/Airliner