Airport Design in Software

Encode QR Code ISO/IEC18004 in Software Airport Design

value of of 12 results in H being about 200 ft when h is 200 ft However, when h is 100 ft, H is 687 ft Consequently, lighting systems designed to aid in aircraft approaching to land on a runway have been designed to provide optimal visual guidance when aircraft are at relatively low altitudes on approach, and are angled to be consistent with the downward approach angle of arriving aircraft

Approach lighting systems (ALS) are designed specifically to provide guidance for aircraft approaching a particular runway under nighttime or other low-visibility conditions While under nighttime conditions it may be possible to view approach lighting systems from several miles away, under other low-visibility conditions, such as fog, even the most intense ALS systems may only be visible from as little as 2500 ft from the runway threshold Studies of the visibility in fog [3] have shown that for a visual range of 2000 to 2500 ft it would be desirable to have as much as 200,000 candelas (cd) available in the outermost approach lights where the slant range is relatively long Under these same conditions the optimum intensity of the approach lights near the threshold should be on the order of 100 to 500 cd A transition in the intensity of the light that is directed toward the pilot is highly desirable in order to provide the best visibility at the greatest possible range and to avoid glare and the loss of contrast sensitivity and visual acuity at short range

The configurations which have been adopted are the Calvert system [3] shown in Fig 8-3 which has been widely used in Europe and other parts of the world, the ICAO category II and category III system shown in Fig 8-4, and the four system configurations which have been adopted by the FAA in the United States shown in Fig 8-5 The FAA publishes criteria for the establishment of the approach lighting systems [13] and other navigation facilities at airports [6] Approach lights are normally mounted on frangible pedestals of varying height to improve the perspective of the pilot in approaching a runway The first approach lighting system was known as the Calvert system In this system, developed by E S Calvert in Great Britain in 1949, includes a line of single bulb lights spaced on 100-ft centers along the extended runway centerline and six transverse crossbars of lights of variable length spaced on 500-ft centers, for a total length of 3000 ft The Calvert system was the first approach lighting system to be certified by ICAO, and is also commonly known as the ICAO category I approach lighting system An illustration of the Calvert system is found in Fig 8-3 The Calvert system is still used in developing countries

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FIGURE 8-3

For operations in very poor visibility, ICAO has certified a modification of the Calvert system, known as the ICAO category II system The variation calls for a higher lighting intensity to the inner 300 m of the system closest to the runway threshold The category II and category III system adopted by ICAO shown in Fig 8-4 consists of two lines of red bars on each side of the runway centerline and a single line of white bars on the runway centerline both at 30 m intervals and both extending out 300 m from the runway threshold In addition, there are two longer bars of white light at a distance of 150 and 300 m from the runway threshold, and a long threshold bar of green light at the runway threshold ICAO also recommends that the longer bars of white light also be placed at distances of 450, 500, and 750 m from the runway threshold if the runway centerline lights extend out that distance as shown in Fig 8-4 The ALSs currently certified by the FAA for installation in the United States consist of a high-intensity ALS with sequenced flashing lights (ALSF-2), which is required for category II and category III precision approaches, a high-intensity approach lighting system with

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