However, additional instrumentation will be necessary in order to assess the severity and frequency of low level wind shear and downdraughts at the site as they may affect aircraft operations.
35.
The studies mentioned in paragraph 33(b) have revealed that there are almost no constraints on aircraft operations to the west and southwest of the site. The mountainous backbone of Lantau island constitutes a barrier to operations south of the site, and the terrain to the north and east would also impose operating constraints. Page 17 of Annex A depicts the potential operating paths for flights departing from the site to the north-east. Although this airspace is somewhat more constrained than the airspace at an ideal airport site, in the opinion of the Consultants improvements expected both in the techniques of airspace management and in the accuracy of air navigation near airports will be such that by the time the full capabilities of the airport are needed hardly any constraints on the operation of the proposed two- runway airport will exist.
36.
Referring to paragraph 33(c) above, the proposed Phase I runway (Annex A, page 12) would meet the requirements of the International Civil Aviation Organisation (ICAO) in respect of airports. The. proposed Phase II runway would also meet the criteria to the south-west but, because of the foothills of Tai Mo Shan, would be slightly below the full requirements to the north-east. Operations on the second runway are not expected to impose additional constraint on the traffic seeking to use the first runway.
An
37.
The separation criteria' referred to in paragraph 33(a) above are, first, the permissible longitudinal spacing between aircraft operating to or from a runway and, secondly, the permissible lateral separation distance between parallel runways. analysis of the airspace north-cast of the site and a study of the optimum spacing between parallel runways led to the conclusions that a pair of runways separated by 900 metros at centreline offered the most useful configuration for the replacement airport. The proposed Phase I runway would enable all forecast types of aircraft to operate on a typically hot day at design stage length carrying maximum payload. Phase II runway is planned to permit 80% of the Hong Kong traffic to operate scheduled sector flights at maximum payload (the remaining 20% being long haul aircraft that have to carry heavy fuel loads and thus require a longer runway to take off without reducing the pay load).
The
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