Runway safety area

A runway safety area (RSA) or runway end safety area (RESA) is defined as "the surface surrounding the runway prepared or suitable for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway."

Past standards called for the RSA to extend only 60m (200 feet) from the ends of the runway. Currently the international standard ICAO requires a 90m (300 feet) RESA starting from the end of the runway strip (which itself is 60m from the end of the runway), and recommends but not requires a 240m RESA beyond that. In the U.S., the recommended RSA may extend to 500 feet in width, and 1,000 feet beyond each runway end (according to U.S. Federal Aviation Administration recommendations; 1000 feet is equivalent to the international ICAO-RESA of 240m plus 60m strip). The standard dimensions have increased over time to accommodate larger and faster aircraft, and to improve safety.

In the early years of aviation, all airplanes operated from relatively unimproved airfields. As aviation developed, the alignment of takeoff and landing paths centered on a well defined area known as a landing strip. Thereafter, the requirements of more advanced aircraft necessitated improving or paving the center portion of the landing strip. The term "landing strip" was retained to describe the graded area surrounding and upon which the runway or improved surface was constructed.

The primary role of the landing strip changed to that of a safety area surrounding the runway. This area had to be capable, under normal (dry) conditions, of supporting aircraft without causing structural damage to the airframe or injury to the occupants. Later, the designation of the area was changed to "runway safety area," to reflect its functional role. The runway safety area enhances the safety of aircraft that undershoot, overrun, or veer off the runway, and it provides greater accessibility for firefighting and rescue equipment during such incidents. One of the difficulties is that overshooting aircraft do not always run off the end of the runway at relatively slow speed; they leave from the side of the runway (as in the TAM Brazilian Airlines Flight 3054 accident), they run off the end at such a high speed that they would overrun any safety area (as in the Air France Flight 358 accident in Toronto), or they land well short of the runway (as in the British Airways Flight 38 accident at Heathrow).

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Wikipedia