Runway System Geometric Specifications

Runway System Geometric Specifications

The runway system at an airport consists of the structural pavement, the shoulders, the blast pad, the runway safety area, various obstruction-free surfaces, and the runway protection zone,

1. The runway structural pavement supports the aircraft with respect to structural load, maneuverability, control, stability, and other operational and dimensional criteria.

2. The shoulder adjacent to the edges of the structural pavement resists jet blast erosion and accommodates maintenance and emergency equipment.

3. The blast pad is an area designed to prevent erosion of the surfaces adjacent to the ends of runways due to jet blast or propeller wash.

4. The runway safety area (RSA) is an area surrounding the runway prepared or  suitable for reducing the risk of damage to aircraft in the event of an undershoot, overshoot, or excursion from the runway. ICAO refers to an area similar to the runway safety area as the runway strip and the runway end safety area. The runway safety area includes the structural pavement, shoulders, blast pad, and stopway, if provided. This area should be capable of supporting emergency and maintenance equipment as well as providing support for aircraft.

The runway safety area is cleared, drained, and graded and should have no potentially hazardous ruts, humps, depressions, or other surface variations. It should be free of objects except for objects that are required to be located in the runway safety area because of their function. These objects are required to be constructed on frangible mounted structures at the lowest possible height with the frangible point no higher than 3 in above grade.

5. The runway object-free area (OFA) is defined by the FAA as a two-dimensional ground area surrounding the runway which must be clear of parked aircraft and objects other than those whose location is fixed by function.

6. The runway obstacle-free zone (OFZ) is a defined volume of airspace centered above the runway which supports the transition between ground and airborne operations. The FAA specifies  this as the airspace above a surface whose elevation is  the same as that of the nearest point on the runway centerline and extending 200 ft beyond each end of the runway.

7. The inner approach obstacle-free zone, which applies only to runways with approach lighting systems, is the airspace above a surface centered on the extended runway centerline beginning 200 ft beyond the runway threshold at the same elevation as the runway threshold and extending 200 ft beyond the last light unit on the approach lighting system. Its width is the same as the runway obstacle-free zone and it slopes upward at the rate of 50 horizontal to 1 vertical.

8. The inner transitional obstacle-free zone, which applies only to precision instrument runways, is defined by the FAA as the volume of airspace along the sides of the runway and the inner approach obstacle-free zone. The surface slopes at the rate of 3 horizontal to 1 vertical out from the edge of the runway obstacle-free zone and the inner approach obstacle-free zone until it reaches a height of 150 ft above the established airport elevation.

9. The runway protection zone (RPZ) is an area on the ground used to enhance the protection of people and objects near the runway approach.

*Facilities for small airplanes only.

†From end of runway; withept,these lengthsthe begindeclaredatthestopend dist of each ASDA and both ends of the LDA, whichever is greater.

‡For runways serving small aircraft only; f the wingspan of the most demanding aircraft plus 20 ft for each 1000 ft of airport elevation.

§For runways serving small aircraft with approach speeds of less than 50 kn; increase to 250 ft for runways serving aircraft with approach speeds greater

than 50 kn.

¶Beyond the end of each runway.