Aerodrome Physical Characteristics: RESA, Stopway, Clearway, and Holding Positions

010-09-03Pablo Asensio Martínez2026-03-272 min

Safety Areas and Defined Zones

  • Runway Strip: A defined area including the runway and stopway, if provided, intended to reduce the risk of damage to aircraft running off a runway and to protect aircraft flying over it.
  • RESA (Runway End Safety Area): An area symmetrical to the extended runway center line and adjacent to the end of the strip. Its purpose is to reduce the risk of damage in case of undershoot or overrun.
    • Location: At each end of the runway strip (not at the end of TORA or TODA).
  • Stopway: A defined rectangular area on the ground at the end of the take-off run (TORA) prepared as a suitable area in which an aircraft can be stopped in case of an abandoned take-off. It has the same width as the runway.
  • Clearway: A defined rectangular area on the ground or water at the end of the TORA selected or prepared as a suitable area over which an aeroplane may make a portion of its initial climb.
  • OFZ (Obstacle Free Zone): The airspace above the inner approach surface, inner transitional surfaces, and balked landing surface and that portion of the strip bounded by these surfaces, which is not penetrated by any fixed obstacle other than a low-mass and frangibly mounted one requires for air navigation purposes.

Holding Positions

  • Runway-holding position:
    • Shall be established at the intersection of a taxiway and a runway.
    • Also at the intersection of two runways if one is part of a standard taxi route.
    • They protect navigation aids (like ILS) and critical obstacle surfaces.
  • Intermediate holding position: A designated position for traffic control where aircraft must stop and hold until authorized.
  • Holding Bay: Recommended when traffic density is medium or heavy.

Taxiways

  • Curves should be designed so that, with the cockpit over the centerline, the main wheels maintain a minimum clearance from the pavement edge.
  • Changes in direction should be as smooth as possible.

Threshold

  • Normally located at the extremity of the runway.
  • May be displaced by obstacles, pavement strength, or noise. A displaced threshold affects the LDA.

Displaced Threshold Diagram arrows indicate the part of the runway available for takeoff and taxiing, but not for landing.