Editing Runway (section)

===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>[https://www.faa.gov/documentLibrary/media/advisory_circular/150-5200-35/150_5200_35.pdf 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>[http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/intro-USA.pdf Jeppesen Airport Chart Legend]</ref>