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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. ==Historical development== 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 airplanes 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 airplanes without causing structural damage to the airplanes or injury to their 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 airplanes which 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 don't always leave the runway straight off the end at relatively slow speed; they leave from the side of the runway (like the Congonhas A320 incident), they leave off the end at such a high speed that they would overrun any safety area (like the AF358 A340 incident in Toronto), or they land well short of the runway (like BA38 B777 incident at Heathrow). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「runway safety area」の詳細全文を読む スポンサード リンク
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