Airports vary in size, with smaller or less-developed airports often having only a single runway shorter than 1,000 m (3,300 ft). Larger airports for international flights generally have paved runways 2,000 m (6,600 ft) or longer. Many small airports have dirt, grass, or gravel runways, rather than asphalt or concrete.



In the United States, the minimum dimensions for dry, hard landing fields are defined by the FAR Landing And Takeoff Field Lengths. These include considerations for safety margins during landing and takeoff. Typically, heavier aircraft require longer runways.

The longest public-use runway in the world is at Ulyanovsk-Vostochny International Airport, in Ulyanovsk, Russia. It has a length of 5,000 m (16,404ft). At 105 m (344ft), it should also be the world's widest paved runway.

As of 2005, there were approximately 50,000 airports around the world, including 19,815 in the United States alone.

Airports are divided into landside and airside areas. Landside areas include parking lots, public transportation stations, tank farms and access roads. Airside areas include all areas accessible to aircraft, including runways, taxiways and ramps. Access from landside areas to airside areas is tightly controlled at most airports. Passengers on commercial flights access airside areas through terminals, where they can purchase tickets, clear security, check or claim luggage and board aircraft though gates. The waiting areas which provide passenger access to aircraft are typically called concourses, although this term is often used interchangeably with terminal.

The area where aircraft park next to a terminal to load passengers and baggage is known as a ramp (or, to the media and uninitiated, "the tarmac"). Parking areas for aircraft away from terminals are generally called aprons.

Both large and small airports can be towered or nontowered, depending on air traffic density and available funds. Due to their high capacity and busy airspace, most 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 more conspicuous level of physical security, although in recent years, many countries have adopted the same level of security for international and domestic travel.

Most international airports have shops and food courts. These services usually provide the passengers food and drinks before they board their flight. Many recognizable chain food restaurants have opened branches in large airports to serve often hungry passengers. International areas usually have a duty-free shop ("Duty Free") where travellers are not required to pay the usual duty fees on items. Larger airlines often operate member-only lounges for premium passengers. London's Heathrow Airport, for example, is home to both a Harrods and a Hamleys Toy Shop, providing Duty Free for international passengers.

Airports have a captive audience, and consequently the prices charged for food is generally higher than are available elsewhere in the region. Airport fees are fees commonly paid for use of services of airports, such as in the Subic Bay International Airport, known for charging airport fees. However, some airports now regulate food costs to keep them comparable to so-called "street prices". This term is a bit misleading as prices often match the MSRP but are almost never discounted.

The vast majority of the world's airports are non-towered, with no air traffic control presence at all. 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 identify and accurately 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 and do not disrupt operations.

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 1000 ft. 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.

Before takeoff, pilots usually check an Automatic Terminal Information Service (ATIS) for information about airport conditions where they exist. The ATIS contains information about weather, which runway and traffic patterns are in use, and other information that pilots should be aware of.

When flying, 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 a perfect approach for landing once they have found the airport. 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 airport. In poor weather, pilots will use an Instrument Landing System 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 guidance signs provide direction and information to taxiing aircraft and airport vehicles and assist in safe and expedient movement of aircraft. Smaller airports may have few or no signs, relying instead on airport diagrams and charts.

There are two classes of signage at airports, with several types of each: