In aviation, a runway is an elongated, rectangular surface designed for the landing and takeoff of an aircraft. Runways may be a human-made surface (often asphalt, concrete, or a mixture of both) or a natural surface (grass, dirt, gravel, ice, sand or salt). Runways, taxiways and ramps, are sometimes referred to as "tarmac", though very few runways are built using tarmac. Takeoff and landing areas defined on the surface of water for seaplanes are generally referred to as waterways. Runway lengths are now commonly given in meters worldwide, except in North America where feet are commonly used.
History In January 1919, aviation pioneer Orville Wright underlined the need for "distinctly marked and carefully prepared landing places, [but] the preparing of the surface of reasonably flat ground [is] an expensive undertaking [and] there would also be a continuous expense for the upkeep." In 1919, based on WWI experience, the United States Army Air Service published Specifications for Municipal Landing Fields. It specified an 1800 by 1800 foot square with a central 150 foot takeoff runway in the shape of a cross. Through the 1930s though, most army planes landed in any direction, subject to the prevailing winds, on circular groomed and drained turf called "all-over fields." However, tire pressures were limited to less than seventy psi in such fields. After 1935, tire pressures exceeded that limit with increased aircraft size. According to Conway, "Confronted with snow and ice removal in the north, water nearly everywhere, and the demands placed by airlines on regularity, safety, and efficient transshipment of passengers and mail, the technology of the all-over turf field became obsolete in the United States during the 1920s." In 1928, Ford Airfield became the first U.S. airport to have concrete runways, and by 1932, all major U.S. airports had runways..."
Design
Orientation The primary consideration in determining runway orientation is the prevailing wind direction, in lieu of spatial constraints or obstructions that may prevent optimal alignment. To mitigate the occurrence of crosswind operations which are more challenging and dangerous, runways at airports are designed to align with the wind's direction. Utilizing runways oriented with the wind direction also allows for aircraft to take-off and land into the headwind, reducing the length of runway used during operations. Taking off and landing into the wind increases the relative air speed of the aircraft to create more lift; this allows aircraft to reach take-off velocity with a shorter amount of ground roll and also allows aircraft to land with a slower ground speed. To determine the prevailing wind directions, analysis of a wind rose is used before constructing airport runways.
Originally in the 1920s and 1930s, airports and air bases (particularly in the United Kingdom) were built in a triangle-like pattern of three runways at 60° angles to each other. The reason was that aviation was only starting, and although it was known that wind affected the runway distance required, not much was known about wind behaviour. As a result, three runways in a triangle-like pattern were built, and the runway with the heaviest traffic would eventually expand into the airport's main runway, while the other two runways would be either abandoned or converted into taxiways.
Naming
Runways are named by a number between 01 and 36, which is generally the magnetic azimuth of the runway's heading in decadegrees. This heading differs from true north by the local magnetic declination. A runway numbered 09 "points" east (90°), in the sense that aircraft taking off or landing on it are moving to the east; similarly, runway 18 points south (180°), runway 27 points west (270°) and runway 36 points north (360° rather than 0°). A runway can normally be used in both directions, and is named for each direction separately: e.g., "runway 15" in one direction is "runway 33" when used in the other. The two numbers differ by 18 (= 180°). For clarity in radio communications, each digit in the runway name is pronounced individually: runway one-five, runway three-three, etc. (instead of "fifteen" or "thirty-three").
A leading zero, for example in "runway zero-six" or "runway zero-one-left", is included for all ICAO and some U.S. military airports (such as Edwards Air Force Base). However, most U.S. civil aviation airports drop the leading zero as required by FAA regulation. This also includes some military airfields such as Cairns Army Airfield. This American anomaly may lead to inconsistencies in conversations between American pilots and controllers in other countries. Military airbases may include smaller paved runways known as "assault strips" for practice and training next to larger primary runways. These strips eschew the standard numerical naming convention and instead employ the runway's full three digit heading; examples include Dobbins Air Reserve Base's Runway 110/290 and Duke Field's Runway 180/360. Runways with non-hard surfaces, such as small turf airfields and waterways for seaplanes, may use the standard numerical scheme or may use traditional compass point naming, examples include Ketchikan Harbor Seaplane Base's Waterway E/W. Airports with unpredictable or chaotic water currents, such as Santa Catalina Island's Pebbly Beach Seaplane Base, may designate their landing area as Waterway ALL/WAY to denote the lack of designated landing direction.
Letter suffix
… excerpt ends here. Continue reading the full article.
