AIRPORT

An airport is a location where aircraft such as airplanes, helicopters, and blimps take off and land. Aircraft may also be stored or maintained at an airport. An airport consists of at least one surface such as a runway, a helipad, or water for takeoffs and landings, and often includes buildings such as hangars and terminal buildings.

Larger airports may have fixed base operator services, seaplane docks and ramps, air traffic control, passenger facilities such as restaurants and lounges, and emergency services.

A military airport is known as an airbase or air station. The terms airfield, airstrip, and aerodrome may also be used to refer to airports, and the terms heliport, seaplane base, and STOLport refer to airports dedicated exclusively to helicopters, seaplanes, or short takeoff and landing aircraft.

In some jurisdictions, the term airport is used where the facility is licensed as such by the relevant government organization (e.g. Federal Aviation Administration (FAA), Transport Canada). Elsewhere the distinction is merely one of general appearance. Yet other areas define an airport by its having the necessary customs offices etc expected of a port,[citation needed] though the more general term is airport of entry.

Airports are divided into landside and airside areas.

• Landside areas include parking lots, public transportation train stations, tank farms and access roads.
  
• Airside areas include all areas accessible to aircraft, including runways, taxiways, ramps commercial flights access airside areas through terminals, where they can purchase tickets, clear security, check or claim luggage and board aircraft through gates.
  

The waiting areas which provide passenger access to aircraft are typically called concourses, although this term is often used interchangeably with terminal. Access from landside areas to airside areas is tightly controlled at most airports.

The area where aircraft park next to a terminal to load passengers and baggage is known as a ramp (or "the tarmac"). Parking areas for aircraft away from terminals are called approns. Airports can be towered or non-towered, depending on air traffic density and available funds. Due to their high capacity and busy airspace, many international airports have air traffic control located on site.

Airports with international flights have customs and immigration facilities. However, as some countries have agreements that allow travel between them without customs and immigrations, such facilities are not a definitive need for an international airport. International flights often require a higher level of physical security, although in recent years, many countries have adopted the same level of security for international and domestic travel.

Modern engineers and architects are developing "floating airports" which could be located several miles at sea and which would use designs such as pneumatic stabilized platform technology.

Premium and VIP services

Airports may also contain Premium and VIP services. The premium and VIP services may include express check in, dedicated check in counters, separate departures and/or arrivals lounge, priority boarding, separate air bridges, and priority baggage handling.

These services are usually reserved for First and Business class passengers, premium frequent flyers, and members of the airlines clubs, however each airline has its own set of rules as to what constitutes a premium passenger and what additional services and benefits are offered.

Premium services may sometimes be open to passengers who are members of a different airlines frequent flyer program. This can sometimes be part of a reciprocal deal, usually due to both airlines been part of the same alliance, or as a ploy to attract premium customers away from rival airlines.

Sometimes these premium services will be offered to a non premium passenger if the airline has made a mistake in handling of the passenger, for instance the passenger is unduly delay, or has their baggage mishandled. However this is up to the discretion of the operating airline.

Airline lounges may include free or reduced rate food, both non alcoholic drinks and alcoholic drinks. Lounges themselves typically have better seating, showers, quite areas, TV’s, computer and internet access, as well as power points which passengers are permitted to use to power laptops or other electronic devices. They will also sometimes employ barista’s, bar persons and high quality chefs.

A certain lounges may restrict the services it provides depending on the time of day, for example they may not serve alcoholic drinks before a certain time of day. They may also only serve certain foods such as breakfast cereals only at certain times of the day.

Airlines sometimes operate multiple lounges within the one airport terminal allowing ultra premium customers, such as first class customers, additional services, which are not available to other premium customers.

Cargo and freight services

In addition to people, airports are responsible for moving large volumes of cargo around the clock. Cargo airlines often have their own on-site and adjacent infrastructure to rapidly transfer parcels between ground and air modes of transportation.

Support services

Aircraft maintenance, pilot services, aircraft rental, and hangar rental are most often performed by a fixed base operator (FBO). At major airports, particularly those used as hubs, airlines may operate their own support facilities.

Some airports, typically military airbases, have long runways used as emergency landing sites. Many airbases have arresting equipment for fast aircraft, known as arresting gear – a strong cable suspended just above the runway and attached to a hydraulic reduction gear mechanism. Together with the landing aircraft's arresting hook, it is used in situations where the brakes would have little or no effect.

Airport Security

Baggage is scanned using X-ray machines, passengers walk through metal detectors
Airport security normally requires baggage checks, metal screenings of individual persons, and rules against any object that could be used as a weapon. Since the September 11, 2001 attacks, airport security has been dramatically increased.

Airport operations

Air traffic control
The majority of the world's airports are non-towered, with no air traffic control presence. However, at particularly busy airports, or airports with other special requirements, there is an air traffic control (ATC) system whereby controllers (usually ground-based) direct aircraft movements via radio or other communications links. This coordinated oversight facilitates safety and speed in complex operations where traffic moves in all three dimensions. Air traffic control responsibilities at airports are usually divided into at least two main areas: ground and tower, though a single controller may work both stations. The busiest airports also have clearance delivery, apron control, and other specialized ATC stations.

Ground Control is responsible for directing all ground traffic in designated "movement areas", except the traffic on runways. This includes planes, baggage trains, snowplows, grass cutters, fuel trucks, and a wide array of other vehicles. Ground Control will instruct these vehicles on which taxiways to use, which runway they will use (in the case of planes), where they will park, and when it is safe to cross runways. When a plane is ready to take off it will stop short of the runway, at which point it will be turned over to Tower Control. After a plane has landed, it will depart the runway and be returned to Ground Control.

Tower Control controls aircraft on the runway and in the controlled airspace immediately surrounding the airport. Tower controllers may use radar to locate an aircraft's position in three-dimensional space, or they may rely on pilot position reports and visual observation. They coordinate the sequencing of aircraft in the traffic pattern and direct aircraft on how to safely join and leave the circuit. Aircraft which are only passing through the airspace must also contact Tower Control in order to be sure that they remain clear of other traffic.


All airports use a traffic pattern (often called a traffic circuit outside the U.S.) to assure smooth traffic flow between departing and arriving aircraft. Generally, this pattern is a circuit consisting of five "legs" that form a rectangle (two legs and the runway form one side, with the remaining legs forming three more sides). Each leg is named (see diagram), and ATC directs pilots on how to join and leave the circuit. Traffic patterns are flown at one specific altitude, usually 800 or 1,000 ft (244 m or 305 m) above ground level (AGL). Standard traffic patterns are left-handed, meaning all turns are made to the left. Right-handed patterns do exist, usually because of obstacles such as a mountain, or to reduce noise for local residents. The predetermined circuit helps traffic flow smoothly because all pilots know what to expect, and helps reduce the chance of a mid-air collision.

At extremely large airports, a circuit is in place but not usually used. Rather, aircraft (usually only commercial with long routes) request approach clearance while they are still hours away from the airport, often before they even take off from their departure point. Large airports have a frequency called Clearance Delivery which is used by departing aircraft specifically for this purpose. This then allows airplanes to take the most direct approach path to the runway and land without worrying about interference from other aircraft. While this system keeps the airspace free and is simpler for pilots, it requires detailed knowledge of how aircraft are planning to use the airport ahead of time and is therefore only possible with large commercial airliners on pre-scheduled flights. The system has recently become so advanced that controllers can predict whether an aircraft will be delayed on landing before it even takes off; that aircraft can then be delayed on the ground, rather than wasting expensive fuel waiting in the air.



Navigational aids
There are a number of aids available to pilots, though not all airports are equipped with them. A Visual Approach Slope Indicator (VASI) helps pilots fly the approach for landing. Some airports are equipped with a VHF omnidirectional range (VOR) to help pilots find the direction to the airport. VORs are often accompanied by a distance measuring equipment (DME) to determine the distance to the VOR. VORs are also located off airports, where they serve to provide airways for aircraft to navigate upon. In poor weather, pilots will use an instrument landing system (ILS) to find the runway and fly the correct approach, even if they cannot see the ground. The number of instrument approaches based on the use of the Global Positioning System (GPS) is rapidly increasing and may eventually be the primary means for instrument landings.

Larger airports sometimes offer precision approach radar (PAR), but these systems are more common at military air bases than civilian airports. The aircraft's horizontal and vertical movement is tracked via radar, and the controller tells the pilot his position relative to the approach slope. Once the pilots can see the runway lights, they may continue with a visual landing.

Airport ground crew

Most airports have ground crew handling the loading and unloading of passengers, crew, baggage and other services.[citation needed] Some ground crew are linked to specific airlines operating at the airport.

Environmental concerns

Aircraft noise is major cause of noise disturance to residents living near airports. Sleep can be affected if the airports operate night and early morning flights. Aircraft noise not only occurs from take-off and landings, but ground operations including maintenance and testing of aircraft. Noise can have other noise health effects. Other noise and environmental concern are vehicle traffic causing noise and pollution on road leading the airport.

The construction of new airports, or addition of runways to existing airports, is often resisted by local residents because of the effect on the countryside, historical sites, local flora and fauna. Due to the risk of collision between birds and airplanes, large airports undertake population control programs where they frighten or shoot birds.

The construction of airports has been known to change local weather patterns. For example, because they often flatten out large areas, they can be susceptible to fog in areas where fog rarely forms. In addition, because they generally replace trees and grass with pavement, they often change drainage patterns in agricultural areas, leading to more flooding, run-off and erosion in the surrounding land.

Some of the airport administrations prepare and publish annual environmental reports in order to show how they consider these environmental concerns in airport management issues and how they protect environment from airport operations. These reports contains all environmental protection measures performed by airport administration in terms of water, air, soil and noise pollution, resource conservation and protection of natural life around the airport.

Source From Wikipedia, the free encyclopedia