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{{Short description|Surface used for takeoff or landing}}
{{Redirect2|Landing strip|RWY|the pubic hairstyle|bikini waxing||RWY (disambiguation)|and|Runway (disambiguation)}}
{{Distinguish|roll way}}
{{Use dmy dates|date=August 2023}}
{{use American English|date=September 2021}}
[[File:Palm Springs International Airport photo Don Ramey Logan.jpg|thumb|Runway 13R at [[Palm Springs International Airport]]]]
[[File:McDonnell Douglas MD-11 KLM - Royal Dutch Airlines, AMS Amsterdam (Schiphol), Netherlands PP1151411211.jpg|thumb|upright|An [[MD-11]] at one end of a runway]]

In [[aviation]], a '''runway''' is an elongated, rectangular surface designed for the [[landing]] and [[takeoff]] of an [[aircraft]].<ref>{{Cite book|title=International standards and recommended practices. Aerodromes. Annex 14 to the Convention on International Civil Aviation|publisher=ICAO|year=1951|pages=17|language=English}}</ref> Runways may be a human-made surface (often [[asphalt concrete|asphalt]], [[concrete]], or [[asphalt concrete|a mixture of both]]) or a natural surface ([[sod|grass]], [[soil|dirt]], [[gravel]], [[ice]], [[sand]] or [[road salt|salt]]). Runways, [[taxiway]]s and [[Airport apron|ramps]], are sometimes referred to as "tarmac", though very few runways are built using [[Tarmacadam|tarmac]]. Takeoff and landing areas defined on the surface of water for [[seaplane]]s are generally referred to as '''waterways'''. Runway lengths are now [[International Civil Aviation Organization#Use of the International System of Units|commonly given in meters worldwide]], except in North America where feet are commonly used.<ref>{{Cite web |last=H |first=Ken |date=2014-09-05 |title=Aviation's Crazy, Mixed Up Units of Measure |url=https://aerosavvy.com/metric-imperial/ |website=AeroSavvy |language=en-US |url-status=live |archive-url= https://web.archive.org/web/20240123211839/https://aerosavvy.com/metric-imperial/ |archive-date= Jan 23, 2024 }}</ref>

==History==
In 1916, in a World War I war effort context, the first concrete-paved runway was built in [[Clermont-Ferrand]] in [[France]], allowing local company [[Michelin]] to manufacture [[Bréguet Aviation]] military aircraft.{{citation needed|date=January 2023}}

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."<ref>{{cite news |url= http://aviationweek.com/blog/1919-orville-wright-future-civil-flying |title= 1919: Orville Wright On The Future Of Civil Flying |date= Jan 10, 2018 |author= Rupa Haria |work= Aviation Week Network |access-date= January 10, 2018 |url-status=dead |archive-url=https://web.archive.org/web/20180110154504/https://aviationweek.com/blog/1919-orville-wright-future-civil-flying |archive-date= January 10, 2018 }}</ref>

==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.<ref>{{cite web |url=http://www.enviroware.com/windrose-pro-for-airports-runway-design |title=WindRose PRO for airports runway design |website=Enviroware  |access-date=2012-02-24}}</ref>

[[File:China lake.jpg|thumb|Triangular runway pattern at Armitage Field, [[Naval Air Weapons Station China Lake]]]]
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.{{cn|date=January 2024}} 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.<ref>{{Cite web|url=https://aviation.stackexchange.com/questions/61396/when-and-why-was-runway-07-25-at-kai-tak-removed|title=When and why was runway 07/25 at Kai Tak removed?|website=Aviation Stack Exchange}}</ref>

===Naming===
[[File:Runway 22.svg|thumb|left|upright|Runway 22]]
[[File:Runway landing designator marking-Numbers.svg|thumb|upright|left|Font and size of numbers and letters]]

Runways are named by a number between 01 and 36, which is generally the [[Compass#How a magnetic compass works|magnetic]] [[azimuth]] of the runway's [[heading (navigation)|heading]] in [[deca-|deca]][[Degree (angle)|degrees]]. This heading differs from [[true north]] by the local [[magnetic declination]]. A runway numbered 09 points east (90°), runway 18 is south (180°), runway 27 points west (270°) and runway 36 points to the north (360° rather than 0°).<ref>[http://www.faa.gov/air_traffic/publications/ATpubs/AIM/Chap2/aim0203.html Federal Aviation Administration Aeronautical Information Manual, Chapter 2, Section 3 Airport Marking Aids and Signs part 3b] {{webarchive|url=https://web.archive.org/web/20120118165015/http://www.faa.gov/air_traffic/publications/atpubs/aim/Chap2/aim0203.html |date=2012-01-18 }}</ref> When taking off from or landing on runway 09, a plane is heading around 90° (east). 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").

[[File:ORD Airport Diagram.svg|thumb|upright|[[FAA]] airport diagram at [[O'Hare International Airport]]. The two 14/32 runways go from upper left to lower right, the two 4/22 runways go from lower left to upper right, and the two 9/27 and three 10/28 runways are horizontal.]]
A leading zero, for example in "runway zero-six" or "runway zero-one-left", is included for all ICAO and some [[United States armed forces|U.S.&nbsp;military]] airports (such as [[Edwards Air Force Base]]). However, most U.S.&nbsp;[[civil aviation]] airports drop the leading zero as required by FAA regulation.<ref>{{cite book | title = FAA Advisory Circular AC 150/5340-1L - Standards for Airport Markings | chapter=Chapter 2.3.e.(2) | chapter-url = http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1022266 | page=17 | quote=A single-digit runway landing designation number is never preceded by a zero.}}</ref> 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.<ref>{{Cite web|url=https://www.amc.af.mil/News/Article-Display/Article/146910/new-assault-landing-strip-opens-in-wyoming-mcchord-c-17-makes-first-landing/|title=New assault landing strip opens in Wyoming; McChord C-17 makes first landing}}</ref> 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.<ref>{{cite web|title=Duke Field (Eglin AF Aux Nr 3) Airport|publisher=Airnav.com|date=July 16, 2020|url=https://www.airnav.com/airport/KMGE|access-date=August 5, 2020}}</ref><ref>{{cite web|title=Dobbins Air Reserve Base|publisher=Airnav.com|date=July 16, 2020|url=https://www.airnav.com/airport/KEGI|access-date=August 5, 2020}}</ref>

Runways with non-hard surfaces, such as small turf airfields and waterways for [[seaplane]]s, may use the standard numerical scheme or may use traditional [[Compass rose|compass point]] naming, examples include [[Ketchikan Harbor Seaplane Base]]'s Waterway E/W.<ref>{{cite web|title=Ketchikan Harbor Seaplane Base
|publisher=Airnav.com|date=July 16, 2020|url=https://www.airnav.com/airport/5KE|access-date=August 8, 2020}}</ref><ref name=ac15035/> Airports with unpredictable or chaotic water currents, such as [[Santa Catalina Island (California)|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.<ref>{{cite web|title=Pebbly Beach Seaplane Base|publisher=Airnav.com|date=July 16, 2020|url=https://www.airnav.com/airport/L11|access-date=August 5, 2020}}</ref><ref name=ac15035/>

===Letter suffix===
[[File:15R-33L - Aeropuerto de Madrid-Barajas - detail.jpg|thumb|left|Runway sign at [[Madrid-Barajas Airport]], Spain]]

If there is more than one runway pointing in the same direction (parallel runways), each runway is identified by appending left&nbsp;(L), center&nbsp;(C) and right&nbsp;(R) to the end of the runway number to identify its position (when facing its direction)—for example, runways one-five-left&nbsp;(15L), one-five-center&nbsp;(15C), and one-five-right&nbsp;(15R). Runway zero-three-left&nbsp;(03L) becomes runway two-one-right&nbsp;(21R) when used in the opposite direction (derived from adding 18 to the original number for the 180° difference when approaching from the opposite direction). In some countries, regulations mandate that where parallel runways are too close to each other, only one may be used at a time under certain conditions (usually adverse [[weather]]).

At large airports with four or more parallel runways (for example, at [[O'Hare International Airport|Chicago O'Hare]], [[Los Angeles International Airport|Los Angeles]], [[Detroit Metropolitan Wayne County Airport|Detroit Metropolitan Wayne County]], [[Hartsfield-Jackson Atlanta International Airport|Hartsfield-Jackson Atlanta]], [[Denver International Airport|Denver]], [[Dallas/Fort Worth International Airport|Dallas–Fort Worth]] and [[Orlando International Airport|Orlando]]), some runway identifiers are shifted by 1 to avoid the ambiguity that would result with more than three parallel runways. For example, in Los Angeles, this system results in runways 6L, 6R, 7L, and 7R, even though all four runways are actually parallel at approximately 69°. At [[Dallas/Fort Worth International Airport]], there are five parallel runways, named 17L, 17C, 17R, 18L, and 18R, all oriented at a heading of 175.4°. Occasionally, an airport with only three parallel runways may use different runway identifiers, such as when a third parallel runway was opened at [[Phoenix Sky Harbor International Airport]] in 2000 to the south of existing 8R/26L—rather than confusingly becoming the "new" 8R/26L it was instead designated 7R/25L, with the former 8R/26L becoming 7L/25R and 8L/26R becoming 8/26.

Suffixes may also be used to denote special-use runways. Airports that have seaplane waterways may choose to denote the waterway on charts with the suffix W; such as [[Daniel K. Inouye International Airport]] in [[Honolulu]] and [[Lake Hood Seaplane Base]] in [[Anchorage, Alaska|Anchorage]].<ref>{{cite web|title=Daniel K Inouye International Airport|publisher=Airnav.com|date=July 16, 2020|url=https://www.airnav.com/airport/PHNL|access-date=August 5, 2020}}</ref> Small airports that host various forms of air traffic may employ additional suffixes to denote special runway types based on the type of aircraft expected to use them, including [[STOL]] aircraft (S), [[Glider (aircraft)|glider]]s (G), [[rotorcraft]] (H), and [[ultralight aviation|ultralight]]s (U).<ref name=ac15035>{{Cite web|url=https://www.faa.gov/documentLibrary/media/advisory_circular/150-5200-35/150_5200_35.pdf|title=FAA AC 150/5200-35}}</ref> Runways that are numbered relative to [[true north]] rather than magnetic north will use the suffix T; this is advantageous for certain airfields in the far north such as [[Thule Air Base]] (08T/26T).<ref>{{Cite web|url=http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/intro-USA.pdf|title=Jeppesen Airport Chart Legend}}</ref>

===Renumbering===
Runway designations may be changed over time as the Earth's magnetic field shifts and their headings shift with it. This is more common at higher latitudes: for example, [[Fairbanks International Airport]] in [[Alaska]] renames runways roughly every 24 years, most recently in 2009.<ref>{{Cite web |date=2017-11-16 |title=Airport Runway Names Shift with Magnetic Field |url=https://www.ncei.noaa.gov/news/airport-runway-names-shift-magnetic-field |access-date=2025-02-10 |website=National Centers for Environmental Information (NCEI) |language=en}}</ref> In northern Canada,<ref>{{Cite web |date=26 December 2024 |title=Designated Airspace Handbook |url=https://www.navcanada.ca/en/dah20241226.pdf |access-date=10 February 2025 |publisher=[[NAV CANADA]] |page=200 |format=PDF}}</ref> runways are designated based on true north, which avoids the need to update them.<ref>{{Cite web |date=October 31, 2024 |title=Requirements for Navigation in Northern Domestic Airspace and Polar Regions |url=https://www.navcanada.ca/en/cnop-9.0-31-oct-2024.pdf |access-date=10 February 2025 |publisher=[[NAV CANADA]] |page=56 |format=PDF}}</ref> [[Nav Canada]], Canada's air navigation service provider, has advocated for an industry-wide switch to true north.<ref>{{Cite web |title=NAV CANADA Switching to TRUE: Pulling away from magnetic north |url=https://www.navcanada.ca/en/news/blog/switching-to-true-pulling-away-from-magnetic-north.aspx |access-date=2025-02-10 |website=www.navcanada.ca |language=en}}</ref>

As runways are designated with headings rounded to the nearest 10°, some runways are affected sooner than others; e.g. a hypothetical Runway&nbsp;23 with a heading of 226° would only have to shift to 224° to become Runway&nbsp;22. Because magnetic drift itself is slow, these changes are uncommon, and not welcomed, as they require accompanying changes in [[aeronautical chart]]s and descriptive documents. When a runway designation does change, it is often done at night, especially at major airports, because [[taxiway]] signs need to be changed and the numbers at each end of the runway need to be repainted to the new runway designators.{{Citation needed|date=February 2025}} In 2009 for example, [[London Stansted Airport]] in the United Kingdom changed its runway designation from 05/23 to 04/22 during the night.<ref>{{Cite web |date=2009-07-06 |title=Stansted Airport changes the name of its runway |url=https://www.dunmowbroadcast.co.uk/news/21684003.stansted-airport-changes-name-runway/ |access-date=2025-02-10 |website=Dunmow Broadcast |language=en}}</ref>

==Declared distances==
<!-- Disambiguation pages and redirects link to this section. --><!-- Which ones? They need to be listed here. --><!-- Runway declared distances should ultimately be given their own separate article on wiki. It is very ineffective to make outside links to one of declared runway distances from other pages to part of this page. -->
[[File:Aim fig 4-3-5 Declared Distances with Full-Standard Runway Safety Areas, Runway Object Free areas, and Runway Protection Zones.jpg|thumb|A breakdown of different declared distances based on the presence of displaced thresholds, stopway, and clearway]]
Runway dimensions vary from as small as {{convert|245|m|abbr=on|0}} long and {{convert|8|m|abbr=on|0}} wide in smaller [[general aviation]] airports, to {{convert|5500|m|abbr=on|0}} long and {{convert|80|m|abbr=on|0}} wide at large [[international airport]]s built to accommodate the largest [[Jet airliner|jets]], to the huge {{convert|11917|x|274|m|abbr=on|0}} lake bed runway 17/35 at [[Edwards Air Force Base]] in California – developed as a landing site for the [[Space Shuttle]].<ref>{{FAA-document|00500ADROGERSLAKEBED|Edwards AFB Rogers Lakebed Airport Diagram}}. [[Federal Aviation Administration]].</ref>

Takeoff and landing distances available are given using one of the following terms:

* {{anchor|Takeoff Run Available|TORA}} '''Takeoff Run Available (TORA)'''<ref name="Contractions">{{cite web|url=http://www.faa.gov/documentLibrary/media/Order/ND/7340.1Z.pdf|title=Order JO 7340.1Z: Contractions|publisher=[[Federal Aviation Administration]]|date=March 15, 2007}}</ref><ref name=":0">{{Cite book|title=ICAO Annex 14, Aerodrome Design and Operations Vol 1.|publisher=ICAO|year=2016|isbn=978-92-9258-031-5|pages=Chapter 1-Definitions, Chapter 2.8-declared distances, Attachment A section 3}}</ref> – The length of runway declared available and suitable for the ground run of an airplane taking off.<ref name="FAR25.189(c)">{{Citation | title = Airplanes: Turbine engine powered: Takeoff limitations | url = http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/07C875546A87CBCD852566EF006B2242?OpenDocument | access-date = 2009-10-04 | archive-date = 16 April 2019 | archive-url = https://web.archive.org/web/20190416021721/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/07C875546A87CBCD852566EF006B2242?OpenDocument | url-status = dead }}</ref>
* {{anchor|Clearway|Takeoff Distance Available|TODA}} '''Takeoff [[Distance]] Available (TODA)'''<ref name="Contractions" /><ref name=":0" /> – The length of the takeoff run available plus the length of the [[Clearway#Aviation|clearway]], if clearway is provided.<ref name="FAR25.189(c)" /> (The clearway length allowed must lie within the aerodrome or airport boundary. According to the [[Federal Aviation Regulations]] and [[Joint Aviation Requirements]] (JAR) TODA is the lesser of TORA plus clearway or 1.5 times TORA).
* {{anchor|Stopway|Accelerate-Stop Distance Available|ASDA}} '''Accelerate-Stop Distance Available (ASDA)'''<ref name="Contractions" /><ref name=":0" />{{nbsp}}– The length of the takeoff run available plus the length of the stopway, if stopway is provided.<ref name="FAR25.189(c)" />
* {{anchor|Landing Distance Available|LDA}} '''Landing Distance Available (LDA)'''<ref name="Contractions" /><ref name=":0" /> – The length of runway that is declared available and suitable for the ground run of an airplane landing.<ref>{{Citation | title = Airplanes: Turbine engine powered: Landing limitations: Destination airports | url = http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/4063CEA6723EAC38852566EF006B269B?OpenDocument | access-date =2009-10-04}}</ref>
* {{anchor|Emergency Distance Available|EMDA}} '''Emergency Distance Available (EMDA)'''<ref name=EMDA>{{cite book|last1=Swatton|first1=Peter J.|title=Aircraft Performance Theory for Pilots|date=2000|publisher=Blackwell Science Ltd|location=Oxford, United Kingdom|isbn=0632055693|page=vii|edition=illustrated, reprint|url=https://books.google.com/books?id=WIstCwAAQBAJ}}</ref> – LDA (or TORA) plus a stopway.

==Sections==
There are standards for runway markings.<ref>[http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/1022266 FAA AC 150/5340-1L – Standards for Airport Markings] pages 13 and following</ref>
{{Wide image|Runway diagram.svg|950}}

* The '''runway thresholds''' are markings across the runway that denote the beginning and end of the designated space for landing and takeoff under non-emergency conditions.<ref>{{Cite web |url=http://128.173.204.63/courses/cee4674/cee4674_pub/markings_airports_rev.pdf |title=Archived copy |access-date=10 July 2013 |archive-date=7 February 2014 |archive-url=https://web.archive.org/web/20140207222155/http://128.173.204.63/courses/cee4674/cee4674_pub/markings_airports_rev.pdf |url-status=dead }}{{dead link|date=November 2025}}</ref>
* The '''[[runway safety area]]''' is the cleared, smoothed and graded area around the paved runway. It is kept free from any obstacles that might impede flight or ground roll of aircraft.
* The '''runway''' is the surface from threshold to threshold (including displaced thresholds), which typically features threshold markings, numbers, and centerlines, but excludes blast pads and stopways at both ends.{{Anchor|blastpad}}
* '''Blast pads''' are often constructed just before the start of a runway where [[jet blast]] produced by large planes during the takeoff roll could otherwise erode the ground and eventually damage the runway.
* '''Stopways''', also known as overrun areas, are also constructed at the end of runways as emergency space to stop planes that overrun the runway on landing or a [[rejected takeoff]].
** Blast pads and stopways look similar, and are both marked with yellow [[Chevron (insignia)|chevrons]]; stopways may optionally be surrounded by red runway lights. The differences are that stopways can support the full weight of an aircraft and are designated for use in an aborted takeoff, while blast pads are often not as strong as the main paved surface of the runway and are not to be used for taxiing, landing, or aborted takeoffs.<ref name="AC 150/5300-13B">{{cite web |url=https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1040834 |title=AC 150/5300-13B - Airport Design |access-date=15 April 2023 }} FAA Advisory Circular 150/5300-13B</ref> An '''[[engineered materials arrestor system]]''' (EMAS) may also be present, which may overlap with the end of the blast pad or stopway and is painted similarly (although an EMAS does not count as part of a stopway).<ref name="AC 150/5300-13B"/>
{{Wide image|Runway diagram, Blast pad.png|950}}
* '''[[Displaced threshold]]s''' may be used for taxiing, takeoff, and landing rollout, but not for touchdown. A displaced threshold often exists because of obstacles just before the runway, runway strength, or noise restrictions making the beginning section of runway unsuitable for landings.<ref>Pilot's Handbook of Aeronautical Knowledge FAA-H-8083-25A, p. 306</ref> It is marked with white paint arrows that lead up to the beginning of the landing portion of the runway. As with blast pads, landings on displaced thresholds are not permitted aside from emergency use or exigent circumstance.
{{Wide image|Runway diagram, Displaced threshold.png|950}}
* '''Relocated thresholds''' are similar to displaced thresholds. They are used to mark a portion of the runway temporarily closed due to construction or runway maintenance. This closed portion of the runway is not available for use by aircraft for takeoff or landing, but it is available for taxi. While methods for identifying the relocated threshold vary, a common way for the relocated threshold to be marked is a ten-foot-wide white bar across the width of the runway.<ref>{{Cite PHAK|year=2016|chapter=14|page=5}}</ref>
* '''Clearway''' is an area beyond the paved runway, aligned with the runway centerline and under the control of the airport authorities. This area is not less than 500&nbsp;ft and there are no protruding obstacles except for threshold lights provided they are not higher than 26 inches. There is a limit on the upslope of the clearway of 1.25%. The length of the clearway may be included in the length of the [[#Declared distances|takeoff distance available]].<ref>US Federal Aviation Regulations, FAR Part 1, Definitions and abbreviations</ref> For example, if a [[#Pavement|paved]] runway is {{convert|2000|m|ft}} long and there are {{convert|400|m|ft}} of clearway beyond the end of the runway, the takeoff distance available is {{convert|2400|m|ft}} long.  When the runway is to be used for takeoff of a large airplane, the [[Maximum Takeoff Weight#Maximum permissible takeoff weight or maximum allowed takeoff weight|maximum permissible takeoff weight]] of the airplane can be based on the takeoff distance available, including clearway.  Clearway allows large airplanes to take off at a heavier weight than would be allowed if only the length of the paved runway is taken into account.

==Markings==
{{More citations needed section|date=June 2022}}
There are runway markings and signs on most large runways. Larger runways have a distance remaining sign (black box with white numbers). This sign uses a single number to indicate the remaining distance of the runway in thousands of feet. For example, a 7 will indicate {{Convert|7000|ft|abbr=on|0}} remaining. The runway threshold is marked by a line of green lights.

[[File:RunwayDiagram.png]]

[[File:Runway Number Painting.jpg|alt=Runway Identifying numbers being painted at Rocky Mountain Metropolitan Airport [KBJC]|thumb|Runway Identifying numbers being painted at [[Rocky Mountain Metropolitan Airport|Rocky Mountain Metropolitan Airport (KBJC)]]]]

There are three types of runways:

* Visual runways are used at small airstrips and are usually just a strip of grass, gravel, ice, asphalt, or concrete. Although there are usually no markings on a visual runway, they may have threshold markings, designators, and centerlines. Additionally, they do not provide an instrument-based landing procedure; pilots must be able to see the runway to use it. Also, radio communication may not be available and pilots must be self-reliant.
* Non-precision instrument runways are often used at small- to medium-size airports. These runways, depending on the surface, may be marked with threshold markings, designators, centerlines, and sometimes a {{Convert|1000|ft|abbr=on|0}} mark (known as an aiming point, sometimes installed at {{Convert|1500|ft|abbr=on|0}}). While centerlines provide horizontal position guidance, aiming point markers provide vertical position guidance to planes on visual approach.
* Precision instrument runways, which are found at medium- and large-size airports, consist of a blast pad/stopway (optional, for airports handling jets), threshold, designator, centerline, aiming point, and {{Convert|500|ft|abbr=on|0}}, {{Convert|1000|ft|abbr=on|0}}/{{Convert|1500|ft|abbr=on|0}}, {{Convert|2000|ft|abbr=on|0}}, {{Convert|2500|ft|abbr=on|0}}, and {{Convert|3000|ft|abbr=on|0}} touchdown zone marks. Precision runways provide both horizontal and vertical guidance for instrument approaches.

Waterways may be unmarked or marked with [[buoy]]s that follow maritime notation instead.<ref>{{Cite web|url=https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/seaplane_handbook/media/faa-h-8083-23-2.pdf|title=FAA-H-8083-23, Seaplane, Skiplane, and Float/Ski Equipped Helicopter Operations Handbook (Chapters 1–3)}}</ref>

For runways and taxiways that are permanently closed, the lighting circuits are disconnected. The runway threshold, runway designation, and touchdown markings are obliterated and yellow "Xs" are placed at each end of the runway and at {{cvt|1000|ft|abbr=on|0}} intervals.<ref>{{Cite PHAK|year=2023|chapter=14|page=14}}</ref>

===National variants===
* In Australia, Canada, the United Kingdom,<ref>{{Cite web|url=https://publicapps.caa.co.uk/docs/33/CAP637%20Visual%20Aids%20Handbook.pdf|title=CAP637, Visual aids handbook, chapter 2, page 3, Issue 2, May 2007, Civil Aviation Authority}}</ref> as well as some other countries or territories ([[Hong Kong]] and [[Macau]]) all 3-stripe and 2-stripe touchdown zones for precision runways are replaced with one-stripe touchdown zones.
* In some South American countries like [[Colombia]], [[Ecuador]] and [[Peru]], one 3-stripe is added and a 2-stripe is replaced with the aiming point.
* Some European countries replace the aiming point with a 3-stripe touchdown zone.
* Runways in Norway have yellow markings instead of the usual white ones. This also occurs in some airports in Japan, Sweden, and Finland. The yellow markings are used to ensure better contrast against snow.
* Runways may have different types of equipment on each end. To reduce costs, many airports do not install precision guidance equipment on both ends. Runways with one precision end and any other type of end can install the full set of touchdown zones, even if some are past the midpoint. Runways with precision markings on both ends omit touchdown zones within {{Convert|900|ft|abbr=on|0}} of the midpoint, to avoid ambiguity over the end with which the zone is associated.

==Lighting==
[[File:Airport lights 1.webp|thumb|Airport runway lights]]
[[File:Runway Landing Light.jpg|thumb|upright|A runway landing light from 1945]]

A line of lights on an airfield or elsewhere to guide aircraft in taking off or coming in to land or an illuminated runway is sometimes also known as a [[Approach lighting system|flare path]].

===Technical specifications===
<!-- Disambiguation pages and redirects link to this section. --><!-- Which ones? They're supposed to be listed here. -->
[[File:A320-cockpit-night.jpg|thumb|Night runway view from [[Airbus A320|A320]] cockpit]]
[[File:Bremen Airport Flugtag 2009 20090510 011.JPG|thumb|Ground light at [[Bremen Airport]]]]

Runway lighting is used at airports during periods of darkness and low visibility. Seen from the air, runway lights form an outline of the runway. A runway may have some or all of the following:<ref name="annex14e3">{{cite web
 |url         = http://legacy.icao.int/fsix/_Library%5CManual%20Aerodrome%20Stds.pdf
 |title       = Aerodrome Design and Operations
 |date        = July 1999
 |edition     = 3
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20120723004923/http://legacy.icao.int/fsix/_Library/Manual%20Aerodrome%20Stds.pdf
 |archive-date = 2012-07-23
}}</ref>
* '''[[Runway end identifier lights]]''' (REIL) – unidirectional (facing approach direction) or omnidirectional pair of synchronized flashing lights installed at the runway threshold, one on each side.
* '''Runway end lights''' – a pair of four lights on each side of the runway on precision instrument runways, these lights extend along the full width of the runway. These lights show green when viewed by approaching aircraft and red when seen from the runway.
* '''[[Runway edge lights]]''' – white elevated lights that run the length of the runway on either side. On precision instrument runways, the edge-lighting becomes amber in the last {{convert|2000|ft|abbr=on|0}} of the runway, or last third of the runway, whichever is less. Taxiways are differentiated by being bordered by blue lights, or by having green center lights, depending on the width of the taxiway, and the complexity of the taxi pattern.
* '''Runway centerline lighting system''' (RCLS) – lights embedded into the surface of the runway at {{convert|50|ft|abbr=on|0}} intervals along the runway centerline on some precision instrument runways. White except the last {{convert|900|m|abbr=on}}: alternate white and red for next {{convert|600|m|ft|abbr=on|0}} and red for last {{convert|300|m|ft|abbr=on|0}}.<ref name="annex14e3"/>
* '''Touchdown zone lights''' (TDZL<ref name="Contractions" />) – rows of white light bars (with three in each row) at {{Convert|30|or|60|m|abbr=on}} intervals on either side of the centerline for {{convert|900|m|abbr=on}}.<ref name="annex14e3"/>
* '''Taxiway centerline lead-off lights''' – installed along lead-off markings, alternate green and yellow lights embedded into the runway pavement. It starts with green light at about the runway centerline to the position of first centerline light beyond the Hold-Short markings on the taxiway.
* '''Taxiway centerline lead-on lights''' – installed the same way as taxiway centerline lead-off Lights, but directing airplane traffic in the opposite direction.
* '''Land and hold short lights''' – a row of white pulsating lights installed across the runway to indicate hold short position on some runways that are facilitating [[land and hold short operations]] (LAHSO).<ref name="annex14e3"/>
* '''[[Approach lighting system]]''' (ALS) – a lighting system installed on the approach end of an airport runway and consists of a series of lightbars, [[strobe light]]s, or a combination of the two that extends outward from the runway end.

According to [[Transport Canada]]'s regulations,<ref>{{cite web
 |url         = http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-aga-7-0-3097.htm#aga-7-8
 |title       = §7.8 Runway Lighting
 |work        = TP 14371: Transport Canada Aeronautical Information Manual
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20130322045731/http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-aga-7-0-3097.htm#aga-7-8
 |archive-date = 2013-03-22
}}</ref> the runway-edge lighting must be visible for at least {{convert|2|mi|abbr=on|0}}. Additionally, a new system of advisory lighting, [[runway status lights]], is currently being tested in the United States.<ref>{{Citation
 |title       = FAA Installs Runway Safety Warning System at LAX
 |url         = http://www.faa.gov/news/press_releases/news_story.cfm?newsId=10609
 |access-date  = 2010-05-14
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20110606185538/http://www.faa.gov/news/press_releases/news_story.cfm?newsId=10609
 |archive-date = 2011-06-06
}}</ref>

The edge lights must be arranged such that:
* the minimum distance between lines is {{convert|75|ft|abbr=on|0}}, and maximum is {{convert|200|ft|abbr=on|0}}
* the maximum distance between lights within each line is {{convert|200|ft|abbr=on|0}}
* the minimum length of parallel lines is {{convert|1400|ft|abbr=on|0}}
* the minimum number of lights in the line is 8.<ref>[http://www.tc.gc.ca/CivilAviation/publications/tp14371/AGA/7-1.htm#7-8 Transport Canada Aeronautical Information Manual] {{webarchive|url=https://web.archive.org/web/20080617185432/http://www.tc.gc.ca/CivilAviation/publications/tp14371/AGA/7-1.htm |date=2008-06-17 }}</ref>
[[File:APPROACH LIGHTS AT BERLIN TEGEL AIRPORT WITH AN AIR UKRAINE BOEING 737-400 TAKING OFF BERLIN GERMANY JUNE 2013 (9023668647).jpg|thumb|[[Approach lighting system]] at [[Berlin Tegel Airport]]]]

===Control of lighting system===
Typically the lights are controlled by a [[control tower]], a [[flight service station]] or another designated authority. Some airports/airfields (particularly [[Non-towered airport|uncontrolled ones]]) are equipped with [[pilot-controlled lighting]], so that pilots can temporarily turn on the lights when the relevant authority is not available.<ref>{{cite web
 |url         = http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-aga-7-0-3097.htm#aga-7-18
 |title       = §7.18 Aircraft Radio Control of Aerodrome Lighting
 |work        = TP 14371: Transport Canada Aeronautical Information Manual
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20130322045731/http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-aga-7-0-3097.htm#aga-7-18
 |archive-date = 2013-03-22
}}</ref> This avoids the need for automatic systems or staff to turn the lights on at night or in other low visibility situations. This also avoids the cost of having the lighting system on for extended periods. Smaller airports may not have lighted runways or runway markings. Particularly at private airfields for light planes, there may be nothing more than a [[windsock]] beside a landing strip.

==Safety==
{{Main|Runway safety}}

Types of runway [[Aviation safety|safety]] incidents include:
* '''Runway excursion''' – an incident involving only a single aircraft, where it makes an inappropriate exit from the runway (e.g. [[Thai Airways#Accidents and incidents|Thai Airways Flight 679]]).
** '''Runway overrun''' (also known as an '''overshoot''') – a type of excursion where the aircraft is unable to stop before the end of the runway (e.g. [[Air France Flight 358]], [[TAM Airlines Flight 3054]], [[Air India Express Flight 812]]).
* '''[[Runway incursion]]''' – an incident involving incorrect presence of a vehicle, person or another aircraft on the runway (e.g. [[Aeroflot Flight 3352]], [[Linate Airport disaster|Scandinavian Airlines Flight 686]]).
* '''Runway confusion''' – an aircraft makes use of the wrong runway for landing or takeoff (e.g. [[Singapore Airlines Flight 006]], [[Western Airlines Flight 2605]]).
* '''Runway undershoot''' – an aircraft that lands short of the runway (e.g. [[British Airways Flight 38]], [[Asiana Airlines Flight 214]]).

==Surface==
{{multiple issues|section=yes|
{{Unreferenced section|date=July 2009}} {{Globalize|date=November 2009}}
}}
[[File:Pista Congonhas03.jpg|thumb|Runway surface at [[Congonhas Airport]] in [[São Paulo]], [[Brazil]]. The grooves increase friction and reduce the risk of [[Hydroplaning (tires)|hydroplaning]].]]
The choice of material used to construct the runway depends on the use and the local ground conditions. For a major airport, where the ground conditions permit, the most satisfactory type of pavement for long-term minimum maintenance is [[concrete]]. Although certain airports have used reinforcement in concrete pavements, this is generally found to be unnecessary, with the exception of [[expansion joint]]s across the runway where a [[dowel]] assembly, which permits relative movement of the concrete slabs, is placed in the concrete. Where it can be anticipated that major settlements of the runway will occur over the years because of unstable ground conditions, it is preferable to install [[asphalt concrete]] surface, as it is easier to patch on a periodic basis. Fields with very low traffic of light planes may use a sod surface. Some runways make use of salt flats.

For pavement designs, borings are taken to determine the subgrade condition, and based on the relative [[bearing capacity]] of the subgrade, the specifications are established. For heavy-duty commercial aircraft, the pavement thickness, no matter what the top surface, varies from {{cvt|10|to|48|in|cm}}, including subgrade.

Airport pavements have been designed by two methods. The first, ''Westergaard'', is based on the assumption that the pavement is an elastic plate supported on a heavy fluid base with a uniform reaction [[coefficient]] known as the [[Hooke's law|K value]]. Experience has shown that the ''K'' values on which the formula was developed are not applicable for newer aircraft with very large footprint pressures.

The second method is called the ''[[California bearing ratio]]'' and was developed in the late 1940s. It is an extrapolation of the original test results, which are not applicable to modern aircraft pavements or to modern aircraft [[landing gear]]. Some designs were made by a mixture of these two design theories. A more recent method is an analytical system based on the introduction of vehicle response as an important design parameter. Essentially it takes into account all factors, including the traffic conditions, service life, materials used in the construction, and, especially important, the dynamic response of the vehicles using the landing area.

Because airport pavement construction is so expensive, manufacturers aim to minimize aircraft stresses on the pavement. Manufacturers of the larger planes design landing gear so that the weight of the plane is supported on larger and more numerous tires. Attention is also paid to the characteristics of the landing gear itself, so that adverse effects on the pavement are minimized. Sometimes it is possible to reinforce a pavement for higher loading by applying an overlay of asphaltic concrete or [[portland cement]] concrete that is bonded to the original slab. Post-tensioning concrete has been developed for the runway surface. This permits the use of thinner pavements and should result in longer concrete pavement life. Because of the susceptibility of thinner pavements to [[Frost heaving|frost heave]], this process is generally applicable only where there is no appreciable [[Weathering#Frost weathering|frost action]].

===Pavement surface===
[[File:Mahan Air A310 EP-MNO.jpg|thumb|A [[Mahan Air]] [[Airbus A310]] using [[reverse thrust]] in rainy weather at [[Düsseldorf Airport]]]]

Runway pavement surface is prepared and maintained to maximize friction for wheel braking. To minimize [[hydroplaning (tires)|hydroplaning]] following heavy rain, the pavement surface is usually grooved so that the surface water film flows into the grooves and the peaks between grooves will still be in contact with the aircraft tyres. To maintain the macrotexturing built into the runway by the grooves, maintenance crews engage in [[airfield rubber removal]] or [[hydrocleaning]] in order to meet required [[FAA]], or other aviation authority friction levels.
[[File:ARC 3000 from Smets Technology removing rubber at DXB.jpg|thumb| ARC 3000 by Smets Technology removing rubber at DXB]]

===Pavement subsurface drainage and underdrains===
Subsurface underdrains help provide extended life and excellent and reliable pavement performance. At the Hartsfield Atlanta, GA airport the underdrains usually consist of trenches {{cvt|18|in|cm}} wide and {{cvt|48|in|cm}} deep from the top of the pavement. A perforated plastic tube ({{cvt|15|cm|order=flip}} in diameter) is placed at the bottom of the ditch. The ditches are filled with gravel size crushed stone.<ref>{{Cite journal|url=https://www.ntnu.no/ojs/index.php/BCRRA/article/view/2723/2786| title=Design, Construction and Maintenance of Concrete Pavements at the World's Busiest Airports  | author1=W. Charles Greer Jr. | author2= Subash Reddy Kuchikulla | author3= Kathryn Masters |author4= John Rone | date = 2013 |work= Proceedings Ninth International Conference on the Bearing Capacity of Roads, Railways and Airfields| volume= 2}}</ref>  Excessive moisture under a concrete pavement can cause pumping, cracking, and joint failure.<ref>[http://www.dot.state.mn.us/materials/pvmtdesign/docs/2007manual/Chapter_5-4_5.pdf] {{Webarchive|url=https://web.archive.org/web/20201019021354/http://www.dot.state.mn.us/materials/pvmtdesign/docs/2007manual/Chapter_5-4_5.pdf |date=19 October 2020 }} Minnesota | Dept. of Transportation| Pavement Manual | 5-4.02 Subsurface Drainage</ref>

==={{anchor|surface_types}} Surface type codes===
[[File:Grass airstrip at badminton england arp.jpg|thumb|The grass airstrip on the Badminton estate, [[Badminton, Gloucestershire|Badminton]], [[South Gloucestershire]], [[England]]. The strip is very simple: no lighting, no centerline, and no approach aids. The edge is marked by simple posts.]]

In [[aviation]] charts, the surface type is usually abbreviated to a three-letter code.

The most common hard surface types are asphalt and concrete. The most common soft surface types are grass and gravel.

{| class="wikitable"
! Abbreviation !! Meaning
|-
| ASP
| [[Asphalt concrete|Asphalt]]
|-
| BIT
| [[Bitumen|Bitumin]]ous asphalt or tarmac
|-
| BRI
| [[Brick]]s (no longer in use, covered with asphalt or concrete now)
|-
| CLA
| [[Clay]]
|-
| COM
| Composite
|-
| CON
| [[Concrete]]
|-
| COP
| Composite
|-
| COR
| [[Coral]] (fine crushed coral reef structures)
|-
| GRE
| Graded or rolled earth, grass on graded earth
|-
| GRS
| [[Grass]] or earth not graded or rolled
|-
| GVL
| [[Gravel]]
|-
| ICE
| [[Ice]]
|-
| LAT
| [[Laterite]]
|-
| MAC
| [[Macadam]]
|-
| PEM
| Partially concrete, asphalt or bitumen-bound macadam
|-
| PER
| Permanent surface, details unknown
|-
| PSP
| [[Marston Matting]] (derived from pierced/perforated steel planking)
|-
| SAN
| [[Sand]]
|-
| SMT
| [[Sommerfeld Tracking]]
|-
| SNO
| [[Snow]]
|-
| U
| Unknown surface
|-
| WAT
| [[Water]]
|}

==Length==
{{Main|List of longest runways}}{{More citations needed section|date=June 2022}}
A runway of at least {{Convert|1800|m|abbr=on}} in length is usually adequate for [[aircraft]] weights below approximately {{convert|100,000|kg|abbr=on}}. Larger aircraft including [[Wide-body aircraft|widebodies]] will usually require at least {{Convert|2400|m|abbr=on}} at sea level. International widebody flights, which carry substantial amounts of fuel and are therefore heavier, may also have landing requirements of {{convert|3200|m|abbr=on}} or more and takeoff requirements of {{convert|4000|m|abbr=on}}. The [[Boeing 747]] is considered to have the longest takeoff distance of the more common aircraft types and has set the standard for runway lengths of larger international airports.<ref>{{Cite web|last=baer|first=jeff|date=2020-11-24|title=Airport Runways - Requirements and Regulations|url=https://www.airplanning.com/post/airport-runways|access-date=2021-11-27|website=Air Planning|language=en}}</ref>

At [[sea level]], {{convert|3200|m|abbr=on}} can be considered an adequate length to land virtually any aircraft. For example, at [[O'Hare International Airport]], when landing simultaneously on 4L/22R and 10/28 or parallel 9R/27L, it is routine for arrivals from [[East Asia]], which would normally be vectored for 4L/22R ({{Convert|2300|m|abbr=on|0}}) or 9R/27L ({{Convert|2400|m|abbr=on|0}}) to request 28R ({{Convert|4000|m|abbr=on|0}}). It is always accommodated, although occasionally with a delay. Another example is that the [[Luleå Airport]] in Sweden was extended to {{convert|3500|m|abbr=on|0}} to allow any fully loaded freight aircraft to take off. These distances are also influenced by the runway [[grade (slope)]] such that, for example, each 1 percent of runway down slope increases the landing distance by 10 percent.<ref>{{Cite book |url=https://flightsafety.org/files/alar_bn8-3-distances.pdf |title=FSF ALAR Briefing Note 8.3 -- Landing Distances |publisher=[[Flight Safety Foundation]] |year=2000 |language=en |access-date=2022-01-20 |archive-url=https://web.archive.org/web/20230120205706/https://flightsafety.org/files/alar_bn8-3-distances.pdf |archive-date=2023-01-20 |url-status=live}}</ref>

An aircraft taking off at a higher altitude must do so at reduced weight due to decreased [[density]] of air at higher altitudes, which reduces engine power and wing lift. An aircraft must also take off at a reduced weight in hotter or more humid conditions (see [[density altitude]]). In the worst case, this is colloquially referred to as [[hot and high]] operation, among the most challenging conditions for takeoff performance. Most commercial aircraft carry manufacturer's tables showing the adjustments required for a given temperature.

<gallery mode="packed" heights="160">
File:No pedestrians (geograph 5985118).jpg|In the 1980s, [[Leeds Bradford International Airport]] extended its runway to take [[wide-body aircraft]] by building an [[overpass]] over the A658 road.
File:Sumburgh Airport Barrier.webm|Road crossing of ([[Shetland]]) A970 with [[Sumburgh Airport]]'s runway. The movable barrier closes when aircraft land or take off.
File:Gibraltar runway 09 & 27.jpg|[[Gibraltar International Airport]]'s runway 09/27, used to be crossed by the one road between Gibraltar and Spain.
File:Atlantis drag chute is open.jpg|A parachute may be used to slow down craft, in this case the [[Space Shuttle]] [[Space Shuttle Atlantis|Atlantis]].
</gallery>

==See also==
{{div col|colwidth=30em}}
* [[Engineered materials arrestor system]]
* [[Helipad]]
* [[Highway strip]]
* [[International Civil Aviation Organization#International System of Units|ICAO recommendations on use of the International System of Units]]
* [[Instrument landing system]] (ILS)
* [[List of airports]]
* [[Pavement classification number]] (PCN)
* [[Precision approach path indicator]]
* [[Roll way]], sometimes referred as a runway<ref>[https://infovisual.info/en/transport/truck-bogie Bogie]</ref>
* [[Runway visual range]]
* [[Tabletop runway]]
* [[Visual approach slope indicator]]
{{div col end}}

==References==
{{Reflist|30em}}

==External links==
{{Commons category|Runway lights}}
{{Wiktionary}}
{{Commons category|Runways|Runway}}
* [https://applications.icao.int/airport-map/ World Airport and Runway Map] (ICAO official site)
* [http://www.faa.gov/air_traffic/publications/media/aim.pdf United States Aeronautical Information Manual] – [[Federal Aviation Administration]] (published yearly)
* [http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/ United States Airport/Facility Directory (d-AFD)] – Federal Aviation Administration (published every 56 days)
* [https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/ United States Terminal Procedures Publication/Airport Diagrams (d-TPP)] – Federal Aviation Administration (published every 28 days)
* [http://www.nappf.com/index.html North American Powered Parachute Federation]
* [http://eddh.de/x-files/dl_files/visual-aids.pdf Visual Aids Handbook] – [[Civil Aviation Authority]]

{{Commercial aviation}}
{{Authority control}}

[[Category:Airport engineering]]
[[Category:Airport infrastructure]]