Parallel Runway System Spacing
The spacing of parallel runways depends on a number of factors such as whether the operations are in VMC or IMC and, if in IMC, whether it is desired to have the capability of accommodating simultaneous arrivals or simultaneous arrivals and departures. At those airports serving both heavy and light aircraft simultaneous use of runways even in VMC conditions may be dictated by separation requirements to safeguard against wake vortices.
aFor airplane design group III serving aircraft with maximum certified takeoff weight greater than 150,000 lb, the standard runway width is 150 ft, the shoulder width is 25 ft, and the blast pad width is 200 ft.
bAirplane design groups V and VI normally require stabilized or paved shoulder surfaces. cFor Airport Reference Code C-I and C-II, a runway safety area width of 400 ft is permissible.
For runways designed after 2/28/83 to serve aircraft approach category D aircraft, the runway safety area width increases 20 ft for each 1000 ft of airport elevation above mean sea level.
dFrom end of runway; with the declared distance concept, these lengths begin at the stop end of each ASDA and both ends of the LDA, whichever is greater.
eFor large aircraft the greater of 400 ft or 180 ft plus the wingspan of the most demanding aircraft plus 20 ft for each 1000 ft of airport elevation; for small aircraft 300 ft for precision instrument runways, 250 ft for all other runways serving small aircraft with
approach speeds of 50 kn or more, and 120 ft for all other runways serving small aircraft with approach speeds less than 50 kn.
fBeyond the end of each runway.
Under VMC, the FAA requires parallel runway centerline separations of 700 ft for all aircraft when the operations are in the same direction and wake vortices are not prevalent. It also recommends increasing
the separation to 1200 ft for airplane design group V and VI runways. If wake vortices are generated by heavy jets and it is desired to operate on two runways simultaneously in VMC when little or no crosswind is present, the minimum distance specified by the FAA is 2500 ft.
For operations under VMC, the ICAO recommends that the minimum separations between the centerlines of parallel runways for simultaneous use disregarding wake vortices be 120 m (400 ft) for aerodrome code number 1, 150 m (500 ft) for aerodrome code number 2, and 210 m (700 ft) for aerodrome code number 3 or 4 runways.
In IMC conditions, the FAA specifies 4300 ft and ICAO specifies 1525 m (5000 ft) as the minimum separation between centerlines of
*The width of a precision approach runway should not be less than 30 m where the aerodrome
code number is 1 or 2.
†Minimum width of pavement and shoulders whe ‡Symmetrical about the runway centerline.
§It is recommended that this be provided for the first 150 m from each end of the runway and that it should be increased linearly from this point to a width of 210 m at a point 300 m from each end of the runway and remain at this width for the remainder of the runway. parallel runways for simultaneous instrument approaches. However, there is evidence that these distances are conservative and steps are being taken to reduce it. The ultimate goal is to reduce this distance by about one-half. For dependent instrument approaches both the FAA and ICAO recommend centerline separations of 3000 ft (915 m). For triple and quadruple simultaneous instrument approaches, the FAA requires 5000-ft separation between runway centerlines, although will allow 4300 ft separations on a case-by-case basis.
Both the FAA and ICAO specify that two parallel runways may be used simultaneously for radar departures in IMC if the centerlines are separated by at least 2500 ft (760 m). The FAA requires a 3500-ft centerline separation for simultaneous nonradar departures. If two parallel runways are to be operated independently of each other in IMC under radar control, one for arrivals and the other for departures, both the FAA and ICAO specify that the minimum separation between the centerlines is 2500 ft (760 m) when the thresholds are even. If the thresholds are staggered, the runways can be brought closer together or must be separated farther depending on the amount of the stagger and which runways are used for arrivals and departures. If approaches are to the nearest runway, then the spacing may be reduced by 100 ft (30 m) for each 500 ft (150 m) of stagger down to a minimum of 1200 ft (360 m) for airplane design groups V and VI and 1000 ft (300 m) for all other aircraft. However, if the approaches are to the farthest runway, then the runway spacing must be increased by 100 ft (30 m) for each 500 ft (150 m) of stagger.