esquerda, direita e centro.
Por exemplo, o Heathrow tem 27 à esquerda (27L) e à direita e 09 à esquerda (09L) e à direita.
Veja aqui para o mapa do aeródromo.
Você pode ver os números perto do final das pistas.
Aqui está um exemplo para um aeródromo com uma pista esquerda de 34.
Se houver mais de três pistas mais ou menos paralelas, um ou mais números de pista serão deslocados em 10 graus, p. 08L, 08C, 08R, 09R.
De o artigo da Wikipedia sobre numeração de pista:
At large airports with four or more parallel runways (for example, at Los Angeles, Detroit Metropolitan Wayne County, Hartsfield-Jackson Atlanta, Denver, Dallas-Fort Worth and Orlando) some runway identifiers are shifted by 10 degrees 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 (approximately 69 degrees). 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 degrees.
Occasionally, an airport with only 3 parallel runways may use different runway identifiers, for example 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.