Runway

According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface (often asphalt, concrete, or a mixture of both) or a natural surface (grass, dirt, gravel, ice, sand or salt). Runways, as well as taxiways and ramps, are sometimes referred to as "tarmac", though very few runways are built using tarmac.

In the aerospace context, a runway is a strip of paved surface on an airport that is used for takeoff and landing of aircraft. Runways are typically oriented in the direction of the wind to allow for the most efficient and safe operation of aircraft. The surface of a runway is usually made of concrete or asphalt and is designed to be strong and durable enough to withstand the heavy loads and high speeds of aircraft during takeoff and landing.

Runways are usually identified by their number and the magnetic azimuth of the runway, which is measured in degrees. The magnetic azimuth is the direction of the runway measured in degrees clockwise from magnetic north. The two main types of runway are:

• A paved runway, which is a prepared surface, usually concrete or asphalt, that is used for takeoffs and landings.
• Unpaved runway, which can be made of gravel, grass, or other natural materials, and are mainly used by smaller aircraft and are found in remote or undeveloped areas.

Examples of runways include:

• John F. Kennedy International Airport's runway, JFK airport have multiple runways which are numbered as 4L, 4R, 13L, 13R and 22L, 22R
• Denver International Airport's runway, Denver airport have multiple runways numbered 17L, 17R, 35L, 35R
• Heathrow Airport's runway, Heathrow airport have two runways numbered 09L, 09R and 27L, 27R

Runways are usually built and maintained by airport authorities, and their design and construction must comply with national and international safety standards and regulations.