An area of land that provides for the taking off, landing, and surface maneuvering of aircraft.
An airport is defined by the type of aircraft it serves and by where it is located. Airports range in size from large commercial air carrier airports, such as Chicago’s O’Hare International Airport, with enplanements, or paid boardings, of more than 30 million passengers per year, to small, privately owned grass landing strips in rural areas with landings of only a few small aircraft each year. In the United States, there are about 15,000 airport landing facilities, only 5,000 of which are open to the public. Even fewer, about 3,000, are served by commercial air 3carrier service. The other airports are small, general aviation airports in private or public ownership.
An airport serves as the transition and exchange point for passengers and cargo between air and ground transportation. Therefore, an airport’s operations include the buildings and facilities that support the transition and exchange of services. Aircraft and passenger facilities often associated with the landing facilities are maintenance, passenger terminal, cargo, fueling, parking, and hangar-storage facilities.
An airport is typically a facility that handles propeller- and jet-driven fixed-wing aircraft. In some countries, the definition for an airport can include landing areas other than on land. Specific areas on rivers and waterways are known as seaports or sealanes. A facility specifically used by helicopters is known as a heliport or helipad. Vertical takeoff and landing (VTOL) aircraft can operate out of special short takeoff and landing (STOL) facilities, heliports, or regular airports. If designed to do so, airports also have the ability to handle helicopters, airships, hot-air balloons, and ultralights.
Although airports may be classified in a number of different ways, the broadest categories are general aviation and commercial service airports. General aviation airports are those that do not receive regularly scheduled passenger service but rather have a primary purpose of serving the aviation interests and needs of small or outlying communities. General aviation includes such activities as corporate and business transportation, recreational flying, aircraft instruction and rental, aerial application, aerial observation, skydiving activities, and other special uses.
Commercial service airports are those that receive scheduled passenger service. These airports can be further classified into large-hub, medium-hub, small-hub, or nonhub airports. The different classifications reflect the number of enplaned passengers boarding aircraft annually at the airport. A large-hub airport will normally have more than five million enplanements, a medium-hub airport more than one million, a small-hub airport more than one-quarter million, and a nonhub airport fewer than one-quarter million.
The term “hub” has more than one meaning in air transportation. For instance, an air traffic hub refers not to an airport, but to the geographic and demographic characteristics of a community. A large air-traffic-hub airport would be associated with a large city from which many people have access to the air transportation system. A medium air-traffic-hub airport would similarly be associated with a medium-sized city, and so forth.
The term hub is also used to describe an airline route structure. An airline hub operation is one where a large number of an airline’s flights converge from distant airports to exchange passengers and then return to those same airports. Because the operation resembles the spokes and the hub of a wheel, it has come to be known as a hub-and-spoke operation. The airports and cities at the end of the spoke served by the main hub airport are commonly known as origination or termination airports, because the majority of those airport’s passenger enplanements originate from the local community.
To ensure that airports are constructed with adequate safety parameters, nations develop their own guidelines in conformance with the International Civil Aviation Organization (ICAO). In the United States, ICAO guidelines are reflected in specific airport design criteria established by the Federal Aviation Administration (FAA). The design criteria are based upon the operational speed and overall size of the aircraft intended to use the airport.
An airport is normally developed according to an airport master plan. A master plan is an overall concept of the long-term development of an airport and serves as a guide for developing the physical facilities of an airport. It takes into account the environmental effects of airport construction and operations, ground-access needs, and economic and financial feasibility. It outlines schedules for the prioritization and phasing of airport improvements. The plan must also conform to the design standards of the federal government. A major product of airport master planning efforts are the airport layout plans and drawings.
An airport’s landing facilities generally consist of a runway or landing strip along with related taxiways and parking areas. A runway is a graded or paved area suitable for the taking off or landing of aircraft. Although most runways in developed nations serving small to large commercial aircraft are paved, there are still many airports that are either grass or dirt strips. These types of landing strips usually serve small piston- or turbine-engine aircraft in rural or undeveloped areas of a country or in developing nations.
In the early days of aviation, dirt and grass runways were the norm. They tended to be wide open field areas that allowed pilots to take off and land in whichever direction the wind was blowing. This is because aircraft weighed relatively little and needed only a short distance to take off.
As aircraft and pavement technology developed and the weight of aircraft increased, the need for longer and stronger runway surfaces emerged. The previously open fields were soon developed into graded areas oriented in the direction of the prevailing winds. These graded areas were then paved. If strong winds occasionally blew from a direction different to that of the paved runway, crosswind runways might also be graded and paved.
Aircraft are designed to land into the wind. When winds blow from a different direction than the orientation of the primary runway, some aircraft are unable to handle the side forces of the wind when landing or taking off. A secondary crosswind runway built to accommodate the occasional crosswind is then used instead of the primary runway.
An airport’s runway configuration is often based upon one of four basic layouts: single, V-shaped, parallel, and intersecting. The many airports built during World War II were arranged in a triangular pattern to accommodate the various wind directions. They were also built to accommodate aircraft that only needed 5,000 feet of land to take off. The introduction of jet aircraft required runways in excess of 7,000 feet.
Along with jet aircraft and increasing passenger and cargo usage came the demand for larger terminal and service buildings, which had to be built within the old airport fence line. These demands shaped many modern airports, where one or two runways were extended and others were closed down to accommodate building facilities. Additional runways of up to 12,000 feet in length and oriented parallel to the others might be added to accommodate larger and heavier aircraft, such as the Boeing 747.
Parallel runways, preferred in large, newly built airports, allow for the greatest number of aircraft operations. Many airports are constrained in capacity by their runway configuration. The runways cannot handle the demand of the aircraft waiting to use them at any particular time without some delay.
The configuration of runways is primarily determined by the prevailing wind direction and the type and volume of expected aircraft activity. Other considerations also affect the layout, including the availability of airspace around an airport to accommodate safe aircraft approaches, departures, and landing patterns; environmental conditions; weather conditions; topography; and the availability of land.
Any paved runway or landing strip is really two runways in one, because each can be used for landing or takeoff in two different directions. Runways are numbered according to the compass heading of the direction in which they are oriented. The numbers are rounded up or down to the nearest whole number and the last-digit zero is dropped. Taxiways are identified by a letter of the alphabet and spoken using the aeronautical alphabet, such as Taxiway Alpha or Taxiway Bravo.
Landing and takeoff surfaces at an airport fall under two general categories: flexible or rigid. Flexible pavements, such as asphalt, dirt, or grass, tend to compress under an aircraft load, whereas rigid pavement, such as cement or concrete, resists compression. The type of pavement used at an airport is determined by the weight of the aircraft expected to use it, and by other factors, such as the expected useful life, anticipated wear characteristics, cost of construction, and exposure to climatic effects.
Because aircraft are affected by the wind and are subject to human inaccuracies in flight and on the ground, safety areas are established in and around an airport to accommodate the safe passage of aircraft. Safety and protection areas help to ensure that the potential for aircraft collision is minimized. They also help prevent serious damage to an aircraft should it go off a runway or taxiway, by allowing it to come to a safe stop without hitting an obstruction.
Within the vicinity of an airport, construction of buildings or towers may be prohibited or restricted in height. Tree heights are also controlled. This is intended to help ensure the structure does not interfere with aircraft in flight and that adequate margins of safety exist.
Taxiways connect the ends of the runways to the main parking and building areas. They are defined pathways used by aircraft to travel on the surface of the airport from one point to another point. Stub taxiways connect the middle portion of a runway with a primary taxiway or taxi route. Stub taxiways can be set at right angles to the runway or set at other angles, in which case they are known as high-speed turnoff taxiways.
Taxilanes are routes that lead from the main taxiway into a parking or terminal area. The design of taxiways and taxilanes must take into account the wingspan and weight of the expected aircraft, so that collisions do not occur with other aircraft or buildings.
Aircraft parking areas are often called ramps, aprons, parking stands, or tie-downs. The various terms are often interchangeable and depend upon local usage. Technically, a ramp is a transition area from a taxiway to an apron, stand, tie-down area, or hangar. Aprons and parking stands are designed for the parking of aircraft, provide access to airport terminal facilities, and allow for the performance of aircraft services. They also accommodate ground vehicle activity.
A tie-down area designates a parking area for primarily general aviation aircraft. Ropes or chains embedded in the ground or pavement are used to secure the aircraft.
All parking areas are structurally designed to accommodate the parking and maneuvering of aircraft. They accommodate the different kinds of ground services, such as fueling, baggage handling, and deicing, provided to the aircraft. Also considered in the design are such things as provisions for electrical, pneumatic, hydraulic, water and lavatory services, access by emergency vehicles, security restrictions, and protection from jet and propeller blast.
On the airport runways, taxiways, and other areas where aircraft operate, special pavement markings help a pilot navigate properly. Runway markings are painted white, whereas taxiway and parking area markings are painted yellow.
The runway markings differ for the different types of navigational equipment used for landing. The intent behind the different markings is to help increase the visual cues a pilot receives as the weather conditions worsen. Markings on a runway identify whether the runway can be used solely by visual reference or with precision or nonprecision instruments in the aircraft.
The pavement surfaces generally have centerlines painted on them to help guide the pilot. Edge markings may also exist. To prevent pilots from mistakenly entering onto a runway from a taxiway, hold-short or stop lines are painted perpendicularly to the taxiway’s centerline. A runway’s centerline is dashed, whereas a taxiway’s centerline is solid.
To further help guide a pilot to a destination on the airport or to distinguish a critical safety marking, signs to the side of the pavement surface accompany the pavement markings. Most signs are internally lighted for enhanced visibility.
Runways, taxiways, and parking areas are also identified at night by the color of lights used to outline them. The runway and taxiway lights outline the perimeter of the pavement. A runway will have primarily white lights, although green, amber (yellow), and red lights are found near the ends of a runway to clearly identify for the pilot the runway ends, or thresholds. Taxiway and parking areas are bordered by blue lights. Lights embedded into the pavement, called in-pavement lights, provide an added visual cue to assist a pilot.
An airport employs a number of different navigational aids to assist pilots in making successful landings, whether the weather is clear or poor. Some of the navigational aids found on an airport are very high frequency omnirange (VOR), localizer (LOC) and glide slope (GS) transmitters, visual approach slope indicators (VASI), Global Positioning Systems (GPS), wind cones, rotating beacon systems, and approach light systems (ALS).
When instrument meteorological conditions (IMC) require pilots to navigate solely through the use of instruments in the airplane instead of outside visual references, the navigational aids align pilots with the runway and help guide the planes down.
An approach light system assists the pilot in making the transition from the instruments in the cockpit to the runway. Newer technology has advanced such that properly equipped airports and aircraft can land in zero-zero conditions, in which there is no visibility either forward or up or down, and the pilot cannot see the lights or runway markings.
The rotating beacon for a land airport is intended to help a pilot easily identify the general location of an airport. Its alternatingly flashing green and white light helps pilots to locate the airport from among all the other lights found in or near a city. The rotating beacon can also be used to communicate with a pilot who has lost radio contact.
Various buildings exist on an airport to serve and accommodate aircraft. The number and type are dependent upon the activity level of the airport, and the kind of aircraft that use it. At a large commercial air carrier airport, the passenger terminal building is the primary structure. The terminal building is designed to serve the needs of the passengers, airlines, and businesses that use it or operate within it. The primary purpose of an airport terminal is to transfer passengers and baggage between surface and air transportation with a minimum of time, confusion, and inconvenience.
The location and design of a terminal is determined by a number of factors, such as the configuration of the runway layout, access to a ground transportation network, future expansion capabilities, design requirements established by the FAA, the surrounding terrain, and environmental impact.
The terminal itself must be able to accommodate the various demands placed upon it by business, international, and leisure travelers and by nonpassengers, such as meeters and greeters, employees, and delivery personnel. All of these people have different needs. International travelers, for instance, are subject to customs, immigration, and security requirements to which local business or leisure travelers are not.
Within a large airport terminal building, there may be all types of businesses, such as car rentals, game rooms, restaurants, and retail stores. Some large airport terminals look like small shopping malls, with stores selling clothing, books, gifts, flowers, and other specialty items.
There are many other buildings situated on an airport. A service center for aircraft is called a fixed-base operator (FBO). An FBO can provide any number of aircraft services, such as fueling, maintenance, avionics, pilot lounges, weather planning, flight training, aircraft and pilot-supply sales, aircraft rental, and sightseeing, charter or air taxi flights.
Also found on airports are hangars and other types of aircraft storage facilities, aviation-related businesses, cargo terminal buildings, fuel storage tanks, airfield maintenance buildings, airport administrative offices, and manufacturing facilities. Many large airports actually resemble small cities, with their own electric power generating plants, wastewater treatment facilities, roadway system, parking facilities, and police and fire rescue buildings.
Gesell, Laurence E. The Administration of Public Airports. 4th ed. Chandler, Ariz.: Coast Aire, 1999. A comprehensive textbook that provides substantive detail on the many aspects of airport management, economics, planning, operation, and liability. Richardson, J. D., J. F. Rodwell, and P. Baty. Essentials of Aviation Management. 5th ed. Dubuque, Iowa: Kendall/Hunt, 1995. An excellent text for reference and overview of the operations of general aviation airports and fixed-based service operations. Wells, Alexander T. Airport Planning & Management. 4th ed. Blue Ridge Summit, Pa.: Tab Books, 2000. A good general-purpose text that covers the various aspects involved in developing and operating an airport.
In the twentieth century, some airports were icons of modernist architecture. The “Theme Building” at Los Angeles International Airport is an example of this type of space age design.